JPH0353268A - Image forming device - Google Patents

Abstract

PURPOSE:To complete the switching of a sorter until a subsequent transfer sheet comes after a proceeding transfer sheet is ejected even when two or more identical images are formed in an image area by setting the speed that a carrying device carries a subsequent transfer sheet lower than the speed that the device carries a proceeding transfer sheet. CONSTITUTION:To copy and form two images, a current mode is checked to be a sort mode where the sorter 18 is used. In the sort mode, a carrying belt 23 is normally driven until the first proceeding transfer sheet passes by a fixing roller 26 out of two transfer sheets on which two identical images formed at the same time are transferred in the image area of a drum 9. After another transfer sheet passes by the fixing roller 26, two-image forming and copying is performed wherein the carrying belt 23 is driven at a speed lower than usual. consequently the time required for the subsequent transfer sheet to come to the sorter 18 is lengthened, and the switching of the sorter 18 completed before the sheet arrives.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION This invention relates to image forming devices, such as electrophotographic color copiers.

Problems with the Prior Art and Inventions For example, in an electrophotographic color copying machine that can make multicolor copies using three colors, red, blue, and black, when making multicolor copies, the image forming body Copying is performed once every three rotations of the photosensitive drum. That is, in the first rotation of the drum, a red developer is used to form a red image in the image area of the drum, and in the second rotation of the drum, a blue developer is used to form a blue image in the image area. During the third rotation of the drum, a black developing device is used to further form a black image over the image area, and this image is transferred onto a sheet of transfer paper. Therefore, when copying a size smaller than half of the maximum size, more than half of the time during which the drum rotates three times is wasted time during which no image is formed or transferred. will decrease. When performing single-color copying using one of red, blue, or black, copying is performed once per rotation of the drum, but more than half of the time during each rotation is wasted. There is no denying that it will be a great time.

To solve this problem, when making multiple copies of less than half the maximum size, two copies of the same image are placed in the image area of the drum.
A copying machine has been proposed in which it is possible to form two or more images and transfer them one by one onto two or more sheets of transfer paper.

On the other hand, some copying machines are equipped with a sorter that sorts and discharges copy sheets after copying.

By the way, when two or more identical images are formed in the image area of the drum as described above, the gap between the preceding transfer paper and the following transfer paper is narrow, so if a sorter is used, the paper will be ejected after the preceding transfer paper is ejected. Inconveniences may occur in that sorter switching is not completed before the next transfer paper arrives.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide an image forming apparatus that does not cause sorter problems even when two or more identical images are formed in an image area of an image forming body.

Means for Solving the Problems An image forming apparatus according to the present invention includes: an image forming body having an image area on its surface; a paper feeding device that supplies transfer paper to the image forming body; It is equipped with a transfer device that transfers the image onto the transfer paper, a conveying device that conveys the transferred transfer paper, a fixing device that has a fixing roller, and a sorter that sorts and discharges the transfer paper that has been fixed. In an image forming apparatus that is capable of forming two or more identical images of half or less of the maximum size in the image area of a forming body and transferring them one by one to two or more sheets of transfer paper, a sorter is used. When used and two or more of the same image are formed in the image area of the image forming body, among the transfer sheets to which two or more images in the image area are transferred, the preceding transfer sheet is transferred to the fixing roller of the fixing device. After passing through the transfer sheet, the conveyance speed of the subsequent transfer sheet by the conveyance device is made smaller than that of the preceding transfer sheet.

The conveyance speed of the subsequent transfer paper may be reduced and then returned to the original conveyance speed after a predetermined period of time has elapsed.

The conveyance speed of the subsequent transfer paper may be reduced, and then the conveyance speed may be returned to the original speed after the preparation of the sorter is completed.

After the first transfer paper passes through the fixing roller of the fixing device,
Since the conveyance speed of the subsequent transfer paper by the conveyance device is set to be lower than that of the preceding transfer paper, the time interval until the subsequent transfer paper reaches the sorter is longer, and during that time, the sorter cannot be switched. can be completed.

Embodiments Hereinafter, embodiments in which the present invention is applied to an electrophotographic color copying machine will be described with reference to the drawings.

FIG. 1 schematically shows the overall structure of a color copying machine, and FIG. 2 schematically shows the mechanical structure of the main parts.

As shown in FIG. 1, a copying machine is roughly divided into a reading section (t), an image processing section (2), a recording section (3), an operation section (4), and a control section (5).

As shown in FIG. 2, the reading section (1) has an original platen (6
), and converts the image into an electrical signal, and includes a carriage (7), a CCD image sensor (8), etc.

The image processing section (2) processes the output of the image sensor (8) of the reading section (1) and sends image information to the control section (5).

The recording section (3) includes a photosensitive drum (9) as an image forming body.
Although not shown, an image area of a certain size (A3 size) is provided on its surface. The drum (9) is driven by an electric motor (24>.A charger (IO), a laser writing device (11>), and three developing devices (12a) (1) are installed around the drum (9).
2b) (12c), a transfer device (13), a cleaning device (14), a paper feed device (i5), a conveyance device (I6), a fixing device (17), a sorter (I8), and other known devices not shown in the drawings. It is being

The red toner is in the first developing device (12a), and the red toner is in the second developing device (12a).
12b) is filled with blue toner, and the third developing device ({2C) is filled with black toner.

The paper feeding device (l5) includes a transfer paper cassette (l9), its first paper feeding roller (20), and its second paper feeding roller (2l). Also, near the second paper feed roller (2i),
A paper feed sensor (22) is provided.

The conveyor device ({6>) includes a conveyor belt (23) and a variable speed electric motor (25) that drives the conveyor belt (23).

The fixing device (l7) includes a fixing roller (2B) and a paper ejection roller (27).The fixing roller (26)
A fixing sensor (28) is provided near the paper ejection roller (27), and a paper ejection sensor (29) is provided near the paper ejection roller (27).

The sorter (18) is equipped with a plurality of upper and lower sorter bins (30).

The operation unit (4>) is a part operated by an operator for copying operations.

The control unit (5) controls each part of the copying machine,
It is equipped with a microcomputer. Note that FIGS. 1 and 2 only show parts directly related to the present invention.

Next, an outline of the operation of the above-mentioned copying machine will be briefly explained with reference to the flowchart shown in FIG.

When the power is turned on, first, necessary initial processing is performed (step 1), input data from the operation section (4) is processed (step 2), and it is checked whether the copy switch has been pressed. (Step 3). Steps 2 and 3 are repeated until the copy switch is pressed, during which time the necessary operations are performed.

When the copy switch is pressed, it is checked whether the selected transfer paper size is half of the maximum size, that is, A4 size or less (step 4), and whether the set number of sheets (number of sheets to be copied from one original) is 2 or more. (Step 5) If the size of the transfer paper is larger than A4 size,
Alternatively, if the set number of copies is one, normal copying is performed in which only one image is formed in the image area of the drum (9) (step 6). If the size of the transfer paper is A4 or smaller and the set number of sheets is 2 or more, form two identical images in the image area of the drum (9>) and print one image on each of the two transfer papers. A two-image forming copy is performed in which each image is transferred one by one.

In the case of two-image format or copying, it is checked whether the sorter (l8) is the sorting mode used (step 7).
). Then, if you are not in sort mode, use the conveyor belt (
23) is always driven at a normal constant speed (normal drive) to perform constant speed two-image forming copying (step 8).
), in the case of sorter mode, of the two sheets of transfer paper on which two identical images formed at once on the image area of the drum (9) are transferred, the first transfer paper is transferred to the fixing roller (26).
), the conveyor belt (23>) is driven normally, and when the first sheet of transfer paper passes the fixing roller (26>), the conveyor belt (23> is driven at a lower speed than the normal speed (low speed drive). A variable speed two-image copy is made (step 9).

The time chart in FIG. 4 shows an example of the operation of each part of the copying machine in the case of variable speed two-image formation copying.

In FIG. 4, the drum index signal and V-S
The YNC signal (vertical synchronization signal) is the writing device (l1)
This is to regulate the writing timing of . The drum index signal is outputted once per rotation of the drum (9) in synchronization with the rotation of the drum (9), and a V-SYNC signal is outputted after a certain period of time. There is a certain relationship between the image area of the drum (9) and the V-SYNC signal, and as shown in the figure, the V-SYNC signal corresponds to the tip of the image area, and the V-SYNC signal is output. The writing device (11) is adapted to correspond to the leading edge of the image area when the image area is opened.

When the V-SYNC signal is output, the carriage (7) of the reading unit (1) scans the document from the tip of the document table (6>), and when the scanning is finished, the carriage (7) moves to the document table (6). Then, while the drum (9) rotates once, the original is scanned twice. While the original is scanned twice, the writing device (l1) Two identical images of the same document are written at a predetermined interval in two places in the image area of .A little later than this writing, one of the developing devices (12a) (1
2b) 2 now formed in the image area by (12e)
Two images are developed.

Meanwhile, at an appropriate time, the first paper feed roller (20) of the paper feed device (l5) is driven for the first time, and the first sheet of transfer paper is sent to the second paper feed roller (21). , paper feed sensor (2
2), the first drive of the first paper feed roller (20) is stopped. Furthermore, at a predetermined interval, the first
The paper feed roller (20) is driven a second time, and the second sheet of transfer paper is sent to the second paper feed roller (2l). Almost at the same time, the second paper feed roller (21) is driven for the first time, and the first sheet of transfer paper is sent toward the drum (9). When the first sheet of transfer paper leaves the second paper feed roller (2l), the paper feed sensor (22) is temporarily turned off;
When the sheet of transfer paper reaches the second paper feed roller (21) and the paper feed sensor (22) is turned on again, the second drive of the first paper feed roller (20) is stopped.

Next, the second paper feed roller (2l) is driven a second time, and the second sheet of transfer paper is sent toward the drum (9). Then, while the two sheets of transfer paper pass through the transfer device (l3) at a predetermined interval, the two transfer sheets pass through the transfer device (l3).
3), the two images in the image area are printed on two sheets of transfer paper.
transcribed one by one.

The transferred paper is sent to the fixing device (l7) by the conveyor bell (23), passes through the fixing roller (26) and the paper ejection roller (27), and is ejected to the sorter bin (30) of the sorter (l8). be done.

When the leading edge of the first sheet of transfer paper conveyed by the conveyance bell (23) passes the fixing roller (26), the fixing sensor (
28) is turned on, and when it passes the paper ejection roller (27),
The paper ejection sensor (29> is turned on.A little while after the leading edge of the first transfer paper passes the paper ejection roller (27), the trailing edge of this transfer paper passes the fixing roller (26) and is fixed. The sensor (28) is turned off.The conveyor belt (23) is normally driven until the trailing edge of the first transfer paper passes the fixing roller (26), but after the first transfer paper When the end passes the fixing roller (2B) and the fixing sensor (28) changes from on to off, the conveyor belt (23) is switched to low speed drive.

The first sheet of transfer paper is placed in the designated sorter bin (18) of the sorter (18).
30) and when the rear end passes the paper ejection roller (27), the paper ejection sensor (29) changes from on to off, and the sorter bin (30) is switched. At this time, the leading edge of the second transfer paper passes the fixing roller (26) and the fixing sensor (28) is turned on again, but since the second transfer paper is fed at a low speed, the leading edge The switching of the sorter bin (30) is completed by the time the paper passes the paper ejection roller (27) and the paper ejection sensor (29) is turned on. Therefore, the second sheet of transfer paper enters the switched sorter bin (30) without any problem, and when the trailing edge passes the paper ejection roller (27) and the paper ejection sensor (29> changes from on to off), it returns again. The sorter bin (30>) is switched.Also, the trailing edge of the second transfer paper passes the fixing roller (26) and the fixing sensor (28)
When the switch turns from on to off, the conveyor belt (23) returns to normal driving again.

If the set number of copies is large, the above operation is repeated and copies are similarly made two copies at a time.

Ru. Then, the first of the two copies to be made at once (
When the odd-numbered transfer paper passes the fixing roller (26),
The conveyor belt (23) is switched to low speed drive, and the second sheet (
When the even-numbered transfer paper passes the fixing roller (26),
The conveyor belt (23) is returned to normal driving, and the first (odd-numbered) of the next two transfer sheets is transferred to the fixing roller (2B).
The conveyor belt (23>) is normally driven until it passes.

At this time, there is a gap between the second (even-numbered) transfer paper of the two copies being copied at once and the first (odd-numbered) transfer paper of the next two copies. Due to the sufficient spacing, the latter can be used as a sorter (
The switching of the sorter bin (30>) is completed by the time the part 18) is reached.

Figure 4 shows the case of monochrome copying. In this case, a monochrome image is formed in the image area with each rotation of the drum (9), and processing below the first paper feed in the figure is performed. It will be done.

On the other hand, in the case of multicolor copying, red, blue, and black images are superimposed in the image area during three rotations of the drum (9), and in the third rotation, the image is lower than the first paper feed in the figure. processing is performed.

The flowchart in FIG. 5 shows an example of the operation of the control unit (5) in the case of variable speed two-image formation copying. In the time chart in FIG. The rear end passes the fixing roller (26) and the fixing sensor <2
8) changes from on to off, the conveyor belt (2)
3) returns to normal operation again,
In the flowchart of FIG. 5, after the first sheet of transfer paper enters the sorter bin (30),
) When the switching is completed, the conveyor belt (23) returns to normal driving again, but the other processes are the same.

In FIG. 5, first, while performing image formation on the drum (9>) including scanning, writing, and development described above (step 10l), the first sheet feeding start timing of the first sheet of transfer paper is checked (step l02). .When the first paper feed start timing comes, the first paper feed signal is turned on (step 10).
3), while driving the first paper feed roller (20) for the first time and continuing image formation (step 104),
Check the first paper feed off timing for the first transfer paper by checking the state of the paper feed sensor (22) (Step 1
05). When the first sheet of transfer paper is sent to the second paper feed roller (2l) and the paper feed sensor (22) is turned on (at the first paper feed off timing), the first paper feed signal is turned off (
Step 106), the first drive of the first paper feed roller (20) is stopped, and while image formation continues (Step 1
07) Check the first sheet feeding start timing of the second sheet of transfer paper (step l08). When the first paper feed start timing comes, the first paper feed signal is turned on (step 109).
), the first paper feed roller (20) is driven for the second time,
While image formation continues (step 110), the second sheet feeding start timing for the first sheet of transfer paper is checked (step 111). When the timing to start the second paper feed is reached, the second paper feed signal is turned on (step 112), the second paper feed roller (2l) is driven for the first time, and while image formation is continued (step l13), the second paper feed signal is turned on (step 112). By checking the state of the paper sensor (22), the second paper feed off timing for the first sheet of transfer paper is checked (step 114). The first sheet of transfer paper passes the second paper feed roller (21) and reaches the paper feed sensor (22).
) turns off (when the second paper feed off timing comes)
, the second paper feed signal is turned off (step 115), the first drive of the second paper feed roller (2l) is stopped, and while image formation is continued (step +16), the paper feed sensor (
22) By checking the condition of the first sheet of the second transfer paper,
The paper feed off timing is checked (step 117). 2
When the sheet of transfer paper is sent to the second paper feed roller (2l) and the paper feed sensor (22) is turned on, the first paper feed signal is turned off (step 118), and the first paper feed sensor (22) is turned on. ) no 2
The second drive is stopped, and while image formation is continued (step 119'), the second sheet feeding start timing for the second sheet of transfer paper is checked (step 120). When the second paper feed start timing comes, the second paper feed signal is turned on (step l
21), the second paper feed roller (2l) is driven for the second time, and while image formation is continued (step l22), the state of the paper feed sensor (22) is checked. Check paper feed off timing (step l23)
. When the second sheet of transfer paper passes the second paper feed roller (2I) and the paper feed sensor (22) turns off, the second paper feed signal is turned off (step 124) and the second paper feed roller (2L) turns off.
) is stopped for the second time, and image formation is continued (step 125).

When image formation is completed (step 12B), the state of the fixing sensor (28) is checked (step 127).

When the trailing edge of the transfer paper passes the fixing roller (26) and the fixing sensor (28) changes from on to off, 1 is added to the counter N (step 128), and it is checked whether N is an odd number (step l29). ). N is initially O and 1
In the case of the th sheet of transfer paper, N is an odd number. Therefore, in the case of the first sheet of transfer paper, the conveyor belt (23) is switched to low speed drive (step 130), and the state of the paper discharge sensor (29) is checked (step 131). The first sheet of transfer paper passes the paper ejection roller (27) and reaches the paper ejection sensor (2).
9) changes from on to off, outputs a switching signal for the sorter bin (30) (step 132), and when switching of the sorter pin (30) is completed (step 133).
, return the conveyor belt (23) to normal drive (step l
34).

Then, check whether the set number of copies have been completed (
Step 135) If the process has been completed, the process is terminated; if it has not been completed, the process returns to step L27. In the case of the second sheet of transfer paper, since N is an even number in step 129, the process advances to step 136 and the paper discharge sensor (
Check the status of 29〉. The second sheet of transfer paper is placed on a haishi roller (
27), when the paper ejection sensor (29) changes from on to off, it outputs a switching signal for the sorter bin (30) (step 137), and when the switching of the sorter bin (30) is completed (step 13g), the set number of sheets is output. It is checked whether copying of has been completed (step l39). If the process has been completed, the process is terminated; if it has not been completed, the process returns to step 101 and the above process is repeated.

In the case of the above embodiment, the second sheet of transfer paper is the fixing roller (26
> or when the switching of the sorter bin (30) is completed, the conveyor belt (23) is returned from low-speed drive to normal drive. It is also possible to return to normal driving when the time period has elapsed.

Effects of the Invention According to the image forming apparatus of the present invention, as described above, even when two or more identical images are formed in the image area of the image forming body, the preceding transfer paper is ejected and then the subsequent transfer paper is ejected. There is no problem such as the sorter switching not being completed before the paper arrives.

[Brief explanation of drawings]

Fig. 1 is a general schematic diagram of an electrophotographic color copying machine showing an embodiment of the present invention, Fig. 2 is a vertical sectional view schematically showing the main parts of the copying machine, and Fig. 3 is an operation of the copying machine. FIG. 4 is a time chart showing the operation of each part of the copying machine, and FIG. 5 is a flow chart showing a part of the process shown in FIG. 3 in detail. (9>...photosensitive drum (image forming body), (13)...
...Transfer device, (l5)...Paper feeder, (16)...
Conveying device, (t7)...Fixing device, (18)...Sorter. that's all

Claims (3)

[Claims] (1) An image forming body having an image area on its surface, a paper feeding device that supplies transfer paper to the image forming body, a transfer device that transfers the image formed in the image area of the image forming body to the transfer paper, and a transfer device. It is equipped with a conveying device that conveys the transfer paper that has been fixed, a fixing device that has a fixing roller, and a sorter that sorts and discharges the transfer paper that has finished fixing. In an image forming apparatus that is capable of forming two or more identical images and transferring them one by one onto two or more sheets of transfer paper, a sorter is used, and the same image is formed in the image area of the image forming body. When two or more images are formed, among the transfer sheets on which two or more images in the image area have been transferred, after the preceding transfer sheet has passed the fixing roller of the fixing device, the subsequent transfer sheet is transferred by the conveying device. An image forming apparatus characterized in that the paper conveyance speed is made smaller than that of the preceding transfer paper. (2) The image forming apparatus according to claim 1, wherein the conveying speed of the subsequent transfer sheet is reduced and then the conveying speed is returned to the original speed after a predetermined period of time has elapsed. (3) The image forming apparatus according to claim (1), wherein the conveying speed of the subsequent transfer paper is reduced and then the conveying speed is returned to the original speed after the preparation of the sorter is completed. .