JP2967355B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Object of the Invention (Industrial Application Field) The present invention relates to an image forming apparatus that forms an image on a single transfer material a plurality of times, such as multiplex copying and duplex copying.

(Prior Art and Problems to be Solved) First, the image forming operation of the known image forming apparatus as described above will be briefly described.

FIG. 6 is a schematic side view showing a typical example of such an image forming apparatus.
The surface photosensitive layer 10 is uniformly charged by the temporary charger 11, and the charged surface is provided with image information 12 such as an image-modulated laser beam to form an electrostatic latent image on the charged surface. You.

Then, as the photosensitive member rotates, the latent image is stored in a plurality of toners containing toners having different colors or characteristics (in the illustrated case,
(Two of the developing devices indicated by reference numerals 13 and 14).

One of these developing units is in an operating position close to the photoreceptor 10 by an external signal, and the other developing units are in an inoperative position away from the photoreceptor.

At the developing site, a toner image corresponding to the latent image is generated on the photoreceptor 10 supplied with toner from a predetermined developing device, and when this toner image further reaches a transfer site provided with a transfer band 15, The toner image is transferred to the transfer material 18 conveyed to the transfer portion at the same timing as that of the toner image by the action of the electrostatic charger, and then the transfer material 18 carrying the toner image is And the toner image is fixed in the fixing device 19.

Thereafter, the transfer material advances by the action of the flapper 20 in the direction of the arrow a shown in FIG.

When the designated number of transfer materials on which the first image formation has been completed are stacked, these transfer materials are sequentially taken out from the refeeding portion 21 and proceed in the direction of arrow c in the drawing, in the same manner as the previous time. After the image formation is performed and passes through the fixing device,
By this time, it is assumed that the flapper 20 is rotated in the clockwise direction from the position shown in FIG.

As described above, when the transfer, the separation, and the fixation are repeated twice or more on one transfer material, whether or not the operation proceeds smoothly may depend on the state of the transfer material. That is, if the transfer material that has passed through the transfer site is curled so as to approach the photoconductor, separation becomes insufficient and separation failure occurs.
This may cause jamming, retransfer, and the like. If the transfer material is curled to the opposite side from the above, after the transfer, the transfer material rushes into the separating band, which may cause a failure.

Further, when the transfer material passes through the fixing device, the fixing of the toner image is usually performed by heating and pressing the transfer material. Therefore, the transfer material is easily dried and curled at this position. Therefore, when the transfer material is subjected to the second and subsequent processes, the same problem as described above may occur.

Looking at the state of the transfer material and the occurrence and frequency of the above-described problems, the larger the curl of the transfer material, the more likely separation failure and retransfer occur. It has been found that retransfer due to curling is remarkable at the leading end of the image.

Therefore, the image ratio for the second and subsequent times is reduced.
It is considered that the above-described problem can be avoided by means such as forming the images after the first time as far as possible from the leading end of the transfer material.

The present invention has been made to cope with such a situation, and when performing image formation on one transfer material a plurality of times, the above-described inconvenience due to changes in the state, characteristics, and the like of the transfer material is eliminated. It is an object of the present invention to provide an image forming apparatus capable of solving the problem and constantly obtaining a high-quality image stably.

(2) Configuration of the Invention (Technical Means for Solving the Problems and Its Action) In order to achieve the above object, the present invention forms the first image of two originals as a toner image on one surface of a transfer material. After fixing the toner image, in an image forming apparatus for sequentially transferring the second image as a toner image to the back surface or the same surface of the transfer material, the image ratio of each document is stored in a document storage device, An image forming apparatus (1) in which a document having a large ratio is compared with a document and transferred to a transfer material first.
Alternatively, the first image of the two documents is formed as a toner image on one surface of the transfer material, and after fixing the toner image, the second image is formed as a toner image on the back surface or the same surface of the transfer material. In an image forming apparatus that sequentially transfers images, the image position of each document is recognized by an image recognition device, and the image position is closer to the leading end in the traveling direction of the transfer material traveling at the time of transfer. An image forming apparatus (2) characterized by transferring.

With this configuration, it is possible to prevent defective separation, retransfer, and the like when performing double-sided, multiple copying, and to stably perform a good image forming operation.

(Description of Embodiment) FIG. 1 is a side view of an image forming apparatus showing an embodiment of the present invention. Since there is no particular change, the description thereof will be omitted.

A document table 30 is disposed on the top surface and other suitable places of such an image forming apparatus. Two documents A and B are placed on the document table 30, and a document storage device 31 stores these documents. In this apparatus, the image ratio of both images is calculated.

As a result, assuming that the image ratio of the original B is high, the image B stored in the storage device 31 on the charging surface of the photoconductor 10 is assumed.
Is exposed by an image writing device 32 such as a laser oscillator.

Subsequent image forming steps are performed in the same manner as in the above-described apparatus.

Next, similarly to the first image formation, the charged surface of the photoreceptor 10 is exposed to the original A having a small image ratio, the image formation is performed in the same manner as described above, and the transfer material is discharged out of the apparatus. Shall be.

By performing the image forming operation in this manner, occurrence of defective separation, retransfer, and the like can be avoided, and it has been confirmed that such an operation is effective in both double-sided copying and multiple copying.

FIG. 2 shows an outline of the above-described series of copying sequences.

FIG. 3 shows another embodiment of the present invention, in which parts corresponding to those of the above-mentioned embodiment are denoted by the same reference numerals.

Reference numeral 31 'denotes an image recognition device which is movable in the vertical direction in the figure and detects an image position on a document.

Before entering the image forming process, the document irradiation lamp 34 and the reflecting mirror 3
5 to 40, at the same time as the optical system moves, the image recognizing device 31 moves downward to recognize the original, and its output signal is transmitted to the processing circuit 33, and which of the two originals A and B is closer to the leading end. The processing order is determined by calculating whether or not an image is present.

Thereafter, image formation is performed in the same order as in the above case.

As described above, the case where the exposure order is determined based on the position where the latent image is formed, the area of the latent image, and each single element has been described. However, it is also possible to determine the exposure order in consideration of both of them. Of course.

FIG. 4 shows still another embodiment, and shows a case in which copying is performed in a mode in which colors are different between the portions C and D as shown in FIG.

In this case, the operator switches the one-point color multiplex changeover switch 41 so that the image exposure of a portion corresponding to the code D having a high image ratio is performed first.

(3) Effects of the Invention As described above, according to the present invention, after the toner image of the first document of the two documents is transferred to the transfer material, the same surface or the other surface of the transfer material is used. When the toner image of the second document is transferred to the document, the image ratio of the two documents is stored by the image storage device, or the position of the image on each document from the leading edge is recognized by the image recognition device, and then the image ratio is changed. Larger documents or documents whose image position is closer to the leading edge of the transfer material in the transfer direction are configured to be transferred first. Therefore, poor separation and retransfer during the second and subsequent transfers are suppressed, and stable and high quality is always achieved. Can get an image of

[Brief description of the drawings]

FIG. 1 is a side view of an image forming apparatus showing an embodiment of the present invention, FIG. 2 is a sequence diagram of the same, FIG. 3 is a side view of an image forming apparatus showing another embodiment of the present invention, FIG. FIG. 5 shows an example of a document to be copied. FIG. 6 is a side view of a known image forming apparatus. 10 ... Photoconductor, 13,14 ... Developer, 15 ... Transfer band, 1
8 Transfer material, 19 Fixing device, 31 Document storage device, 3
2 ... Image writing device, 31 '... Image recognition device.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G03G 15/22 G03G 15/14 G03G 15/00 106

Claims (2)

(57) [Claims] An image of a first sheet of two originals is formed as a toner image on one surface of a transfer material, and after fixing the toner image, the second image is formed on the back surface or the same surface of the transfer material. An image forming apparatus for sequentially transferring as a toner image, wherein an image ratio of each document is stored in a document storage device, the image ratio is compared, and a document having a higher ratio is transferred to a transfer material first. apparatus. 2. The method according to claim 1, wherein the first image of the two originals is formed as a toner image on one surface of a transfer material, and after fixing the toner image, the second image is formed on the back surface or the same surface of the transfer material. In an image forming apparatus that sequentially transfers as a toner image, the image position of each document is recognized by an image recognition device, and the image position of the transfer material traveling at the time of transfer is closer to the leading end in the traveling direction. An image forming apparatus for transferring an image onto a transfer material.