JPH10232563A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which prevents soil on the back of printing paper and can change transfer time according to an image size. SOLUTION: The image forming device of an orthogonal transfer system transfers a toner image held on a photoreceptor 1 to the printing paper by means of a transfer opposite roller 8 in a direction orthogonal to the direction in which the printing paper 7 is carried, and fixes the toner image transferred to the printing paper. The image forming device is provided with a return detector 13 for detecting the position of moving transfer opposite roller, and a control part for reversing the direction of the movement of the transfer opposite roller when the position detected by the detector 13 coincides with a specific position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an orthogonal transfer system for transferring a toner image onto a print sheet in a direction perpendicular to a conveying direction of the print sheet.

[0002]

2. Description of the Related Art In recent years, toner-type image forming apparatuses, such as laser printers, capable of forming clear images with excellent resolution have become widespread. Among such toner-type image forming apparatuses, as proposed in Japanese Patent Application No. 7-328600, the photoconductor is rubbed against the printing paper while moving the photoconductor in a direction orthogonal to the conveyance direction of the printing paper. An orthogonal transfer type image forming apparatus that transfers a toner image step by step in small steps is very suitable for promoting miniaturization of a product due to its configuration.

FIG. 5 is a schematic view showing the structure of a general orthogonal transfer type image forming apparatus, FIG. 6 is a perspective view showing the main parts of a conventional orthogonal transfer type image forming apparatus, and FIG. FIG. 9 is a moving state diagram showing a moving state of a transfer opposing roller of a conventional orthogonal transfer type image forming apparatus. 5, 6 and 7, 1 is a photoreceptor, 2 is a charger, 3 is a developer, 3a is a toner, 3b is a developing roller, 3c is a toner image, 4 is a photoreceptor cleaner, and 5 is a static eliminator. , 6 is an exposure device, 7 is a printing paper, 8 is a transfer opposing roller, 9a to 9c are photosensitive rollers,
Reference numeral 10 denotes a transfer plate, and reference numeral 11 denotes a printing paper transport roller.

As shown in FIG. 5, a photoreceptor 1 having a surface coated with an organic photoconductive material is provided with a photoreceptor roller 9a.
9c and the transfer facing roller 8, and is rotatable in the direction of arrow A. In the rotation direction of the photoconductor 1, a photoconductor cleaning device 4, a static eliminator 5, a charging device 2, an exposure device 6, and a developing device 3 are arranged in this order, and the developing device 3 contains a toner 3a. . Also,
The printing paper 7 is supported by the transfer plate 10 and is transported by the printing paper transporting rollers 11 in a direction C perpendicular to the direction of the arrow A in which the photoconductor 1 rotates, as shown in FIG.

The operation of the conventional orthogonal transfer type image forming apparatus configured as described above will be described. When an image forming operation is instructed by a control unit (not shown) of the image forming apparatus, the photoconductor rollers 9a to 9c are rotated by a photoconductor roller driving unit (not shown), and the photoconductor 1 is moved in the direction of arrow A. Start turning. First, after the surface of the photoreceptor 1 is charged by the charger 2 in accordance with the content of the image to be formed, an electrostatic latent image is formed on the charged portion by the laser beam 6a emitted from the exposure unit 6. It is formed.

When the portion of the photoreceptor 1 where the electrostatic latent image is formed reaches the position of the developing unit 3, the developing roller 3b disposed in the developing unit 3 is rotated by a developing roller driving unit (not shown). It comes into contact with the photoconductor 1. As a result, while the photoconductor 1 is being nipped and moved between the developing roller 3b and the photoconductor roller 9b, the electrostatic latent image is developed by the toner 3a attached to the surface of the developing roller 3b. To form a toner image 3c.

After the toner image 3c corresponding to one sheet of printing paper is formed on the photoconductor 1 by the above operation, the transfer of the toner image 3c from the photoconductor 1 to the printing paper 7 is performed.

When transferring the toner image 3c, first, a tip portion p1 of the toner image 3c formed on the photoreceptor 1 (FIG. 5)
Is substantially at the same position as the end p2 of the image forming area of the printing paper 7, the rotation of the photoconductor rollers 9a to 9c is stopped and the rotation of the photoconductor 1 is stopped.

Next, a sheet conveying roller driving section (not shown)
As a result, the printing paper transport roller 11 rotates,
As shown in FIG. 6, the printing paper 7 moves on the transfer plate 10 in a direction perpendicular to the rotation direction A of the photoconductor 1 (printing paper conveying direction) C.
Is transported to a predetermined position. When the conveyance of the printing paper 7 is completed, the transfer opposing roller drive unit (not shown) moves the transfer opposing roller 8 from the transfer start position p3 to the transfer end position p4 (see FIG. 6 and FIG. 7). 7) is translated along the printing paper 7 until 7). During the parallel movement of the transfer opposing roller 8, the photoconductor 1 is sequentially pressed against the printing paper 7 by the transfer opposing roller 8, so that the toner image 3 c on the photoconductor 1 is transferred onto the printing paper 7. .

When the transfer of the toner image is completed, the print paper transport roller 11 rotates again, and the print paper 7 on which the image has been formed is discharged. When the discharge of the printing paper 7 is completed, the photoconductor 1 starts to rotate again, and the toner remaining on the photoconductor 1 is removed by the photoconductor cleaning unit 4 from the portion of the photoconductor 1 on which the toner image 3c has been transferred. After that, the charge on the photoconductor 1 is erased by the neutralizer 5.

As described above, predetermined images such as characters and figures are formed on one print sheet 7, and similar image forming operations are sequentially repeated as necessary.

[0012]

However, in the above-described conventional image forming apparatus, even when a small print sheet is used, the transfer opposing roller 8 moves to the maximum, so that an extra portion of the photosensitive member 1 that is not pressed by the print sheet is used. When there is an unusual toner, the toner moves toward the transfer plate 10, and thereafter,
When a large printing paper is used, there is a problem that the toner transferred to the transfer plate 10 is stained on the back surface of the large printing paper (backside stain). Further, regardless of the size of an image to be printed, since the transfer distance of the transfer opposing roller 8 is the same, the time required for transfer is the same, and there is a problem that efficiency is poor.

In this image forming apparatus, it is required that the back stain of the printing paper does not occur and that the transfer time can be changed according to the size of the image.

According to the present invention, the back stain of the printing paper does not occur,
It is another object of the present invention to provide an image forming apparatus capable of changing the transfer time according to the size of an image.

[0015]

SUMMARY OF THE INVENTION In order to solve this problem, an image forming apparatus according to the present invention uses a transfer opposing roller to transfer a toner image carried on a photoreceptor onto a printing sheet in a direction orthogonal to a conveying direction of the printing sheet. An orthogonal transfer type image forming apparatus for transferring and fixing the toner image transferred to the printing paper,
There is provided a configuration having a detector for detecting the position of the moving transfer opposing roller, and a control unit for reversing the moving direction of the transfer opposing roller when the position detected by the detector becomes a predetermined position.

Thus, an image forming apparatus can be obtained in which the back stain of the printing paper does not occur and the transfer time can be changed according to the size of the image.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to a first aspect of the present invention, a toner image carried on a photoreceptor is transferred to a printing paper in a direction orthogonal to a conveying direction of the printing paper by a transfer opposing roller. An image forming apparatus of an orthogonal transfer type for fixing a toner image transferred to a transfer device, wherein a detector for detecting the position of a moving transfer opposing roller and a position detected by the detector become a predetermined position A control unit for reversing the moving direction of the transfer opposing roller is provided, which has an effect that the moving width of the transfer opposing roller can be changed according to the situation.

According to a second aspect of the present invention, in the first aspect of the present invention, there is provided a paper feeding unit for detecting a size of the printing paper, and the control unit adjusts the size of the printing paper detected by the paper feeding unit. The predetermined position is determined accordingly, and by controlling the moving distance of the transfer opposing roller, it is possible to prevent the toner image from being transferred beyond the width of the printing paper.

According to a third aspect of the present invention, in the first aspect of the present invention, the image processing apparatus further comprises an image processing section for detecting a width of the image data to be developed, and the control section controls the image data detected by the image processing section. The predetermined position is determined according to the width of the transfer roller. By controlling the moving distance of the transfer opposing roller, the transfer time can be shortened in accordance with the image data.

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 is a perspective view showing a main part of an image forming apparatus according to a first embodiment of the present invention. FIG. 2 shows a moving state of a transfer facing roller when a width of a printing paper is small. FIG. 3 is a movement state diagram showing the movement state of the transfer opposing roller when the width of the printing paper is large. Figure 1
3, the photoconductor 1, developing unit 3, exposure unit 6, printing paper 7, transfer opposing roller 8, photoconductor rollers 9a and 9c, transfer plate 10, and printing paper transport roller 11 are the same as those in FIGS. Therefore, the same reference numerals are given and the description is omitted.

Reference numerals 12a and 12b denote sheet feeding guides, and reference numeral 13 denotes a turn-back detector for detecting the transfer opposing roller 8 in order to turn the transfer opposing roller 8 forward, that is, to change the direction from advance to retreat.

The operation of the image forming apparatus configured as described above will be described. In FIG. 1, the paper feed guide 12a is fixed, and one side of the printing paper 7 is always aligned with the paper feed guide 12a. Thereafter, the paper feed guide 12b can be moved according to the size of the printing paper 7. Although not shown, a return detector 13 of the transfer opposing roller 8 is interlocked with the paper feed guide 12b,
The folding detector 13 of the transfer opposing roller 8 also moves right and left in accordance with the movement of the paper feed guide 12b. This paper feed guide 12b
Is controlled by a control unit (not shown) to move the return detector 13 to the left or right in accordance with the movement of. When the turnback detector 13 detects the transfer opposing roller 8 moving forward, the transfer opposing roller 8 moves in the direction opposite to the direction of arrow B (forward direction) (backward direction).
And return to the original waiting area. When the width of the printing paper 7 is small, as shown in FIG. 2, the return detector 13 of the transfer opposing roller 8 moves inward, and the transfer opposing roller 8 returns at the illustrated position. When the width of the printing paper 7 is large, as shown in FIG.
Does not move from the end, and as shown, the transfer opposing roller 8 is folded back after moving to the maximum.

As described above, according to the present embodiment, the transfer opposing roller 8 can be moved according to the size of the printing paper 7, and the transfer opposing roller 8 moves over the The transfer of the toner image to the printing paper can be prevented, and the occurrence of back contamination on the printing paper can be prevented.

(Embodiment 2) An image forming apparatus according to Embodiment 2 of the present invention differs from Embodiment 1 in the operation of a control unit for moving the folding detector 13 right and left.

The operation of the image forming apparatus according to the present embodiment will be described with reference to FIGS.
FIGS. 4A to 4E are explanatory diagrams of the operation in the second embodiment. FIG. 4A shows an image data area, FIG. 4B shows a toner image corresponding to the image data area in FIG. 4A, and FIG. 4C shows a toner image corresponding to the toner image in FIG. 4D and 4E show the state of movement of the transfer opposing roller 8. 4A to 4E, the toner image 3c, the printing paper 7, the transfer opposing roller 8,
Since the return detector 13 is the same as that in FIGS. 1 to 3, the same reference numerals are given and the description is omitted. Reference numeral 14 denotes an image data area in the image data storage memory 15.

The image data storage memory 1 shown in FIG.
Image data amount (image data area) 14 stored in 5
Accordingly, the size (width) of the image formed on the photoconductor 1 is determined as shown by the toner image 3c in FIG. The control unit (not shown) calculates the size of the image, and moves the return detector 13 of the transfer opposed roller so that the transfer opposed roller 8 moves by the size of the image (FIG. 4).
(C)). Thereafter, when the transfer is performed by moving the transfer opposing roller 8, only the portion where the toner image 3c exists is transferred (FIG. 4).
(D)), the transfer opposing roller 8 moves in the reverse direction (retreat direction), and returns to the original standby position shown in FIG.

In the first and second embodiments,
Although the folding detector 13 is used to detect the position of the transfer opposing roller 8, the position may be detected using the number of pulses of the transfer opposing roller 8.

As described above, according to the present embodiment, the transfer opposing roller 8 moves in the forward direction by the size (width) of the image, and moves in the retreating direction at a position where the transfer opposing roller 8 exceeds the size of the image. As a result, the transfer opposing roller can be moved in accordance with the size of the image to be printed, and the transfer time is shortened when the image to be printed is small.

[0029]

As described above, according to the image forming apparatus of the present invention, by detecting the position of the moving transfer opposing roller, the moving direction of the transfer opposing roller is reversed when it reaches a predetermined position. Therefore, the transfer opposing roller can be moved in accordance with the size (width) of the printing paper, thereby preventing the transfer of the toner image onto the transfer plate due to the transfer opposing roller exceeding the width of the printing paper. This has the advantageous effects of preventing the occurrence of back contamination on the printing paper and shortening the transfer time.

The image forming apparatus further includes a paper feeding unit for detecting the size of the printing paper, and the control unit determines the predetermined position according to the size of the printing paper detected by the paper feeding unit, thereby moving the transfer opposing roller. Since the distance can be controlled according to the size (width) of the printing paper, it is possible to prevent the transfer of the toner image beyond the width of the printing paper, and to prevent the back stain of the printing paper. The advantageous effect that it can be obtained is obtained.

The image processing apparatus further comprises an image processing unit for detecting the width of the image data to be developed, and the control unit determines a predetermined position in accordance with the width of the image data detected by the image processing unit, so that the transfer facing roller is determined. Can be controlled according to the width of the image data, so that an advantageous effect that the transfer time can be shortened in accordance with the image data can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main part of an image forming apparatus according to a first embodiment of the present invention;

FIG. 2 is a moving state diagram showing a moving state of a transfer opposing roller when a width of a print sheet is small.

FIG. 3 is a moving state diagram showing a moving state of a transfer opposing roller when a width of a printing paper is large.

4A is a diagram illustrating an operation according to a second embodiment. FIG. 4B is a diagram illustrating an operation according to a second embodiment. FIG. 4C is a diagram illustrating an operation according to the second embodiment. Explanatory diagram (e) Explanatory diagram of operation in Embodiment 2.

FIG. 5 is a block diagram schematically showing a general orthogonal transfer type image forming apparatus.

FIG. 6 is a perspective view showing a main part of a conventional orthogonal transfer type image forming apparatus.

FIG. 7 is a moving state diagram showing a moving state of a transfer opposing roller of a conventional orthogonal transfer type image forming apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor 2 charging device 3 developing device 3a toner 3b developing roller 3c toner image 4 photoconductor cleaning device 5 static eliminator 6 exposure device 7 printing paper 8 transfer facing rollers 9a to 9c photoconductor roller 10 transfer plate 11 printing paper transport roller 12a , 12b Paper feed guide 13 Turnback detector 14 Image data area 15 Image data storage memory

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yasunori Sagara 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Shinichi Kizu 1006 Kazuma Kadoma, Osaka Pref.Matsushita Electric Industrial Co., Ltd. 1006 Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. An orthogonal transfer type image in which a toner image carried on a photoreceptor is transferred to a printing sheet by a transfer opposing roller in a direction orthogonal to a conveying direction of the printing sheet, and the toner image transferred to the printing sheet is fixed. A forming device, comprising: a detector for detecting a position of the transfer opposing roller to move; and a control unit for reversing a moving direction of the transfer opposing roller when the position detected by the detector becomes a predetermined position. An image forming apparatus comprising: 2. The apparatus according to claim 1, further comprising a sheet feeding unit for detecting a size of the printing sheet, wherein the control unit determines the predetermined position according to the size of the printing sheet detected by the sheet feeding unit. Item 2. The image forming apparatus according to Item 1. 3. An image processing unit for detecting a width of image data to be developed, wherein the control unit determines the predetermined position according to the width of the image data detected by the image processing unit. The image forming apparatus according to claim 1, wherein: