JPS63147747A - Image forming device - Google Patents

Abstract

PURPOSE:To eliminate shifting of a picture image by scanning a detecting part in the direction of crossing a sheet end part at a right angle on a sheet conveying course in the vicinity of an image forming part to detect the lateral direction position of a sheet end part and carrying out correction so as to make positions agree through a second detecting means and a position correcting means which are provided on a course for copying. CONSTITUTION:A first sheet end part lateral direction position detecting means is provided on a sheet conveying course in the vicinity of an image forming part 2. This first detecting means is formed with a photo sensor 65 consisting of a photo interrupter. The light emitting part 65a and light receiving part 65b of the photo sensor 65 is integrally held by an arm 65c which is rotatably supported by a pin 66 fixed to a body. The groove 65d of the arm 65c interposingly holds a disk cam 67 which is installed on a register roller 22 from both sides, and the photo sensor 65 is reciprocated in the Z direction with respect to a sheet S. The lateral direction position is detected by the passing time of the photo sensor 65 and, based on the difference between the detected values of the sensor 65 and a second position detecting means, the position is corrected to eliminate the shifting of a picture image.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to image forming apparatuses such as copying machines and laser beam printers, and more particularly, to image forming apparatuses such as copying machines and laser beam printers. -Relates to an image forming apparatus configured to perform multiple image formation or double-sided image formation.

(B) Prior Art Recently, as an image forming apparatus such as a copying machine (hereinafter referred to as a copying machine), an apparatus as shown in FIG. 5 has been devised by the present applicant (not publicly known).

The copying device 1 has a copying device main body 3 that includes a copying section (image forming section) 2, and includes a copying device main body 3, a document mounting table 5, a light source 6, a lens system 7, two cassettes 9a, 9b
The copying section 2, which includes a cylindrical photoreceptor 10 and the like, is disposed approximately at the center of the main body 3 of the apparatus.

Near the periphery of the photoreceptor 10, there are two developing devices 11a and 1lb1 each containing toner of a different color.
Cleaner 12, charger 13, and conveyance roller 1
A transfer charger 15 and a separation charger 16 are disposed at the tip of the conveyance device 17 having 7a, 17b, and 17c. Also, cassette 1-9
Paper feed rollers 19a and 19b are arranged in portions a and 9b, and the transfer sheet S is guided to a pair of registration rollers 22 via a pair of transport rollers 20a and 20bS paths 21m and 21b, respectively. At the same time, a transfer rate for multiple copying or duplex copying is guided by the pair of registration rollers 22 via a sheet conveying section 23 disposed below the main body 3 of the apparatus. Further, a fixing device (fixing section) 25 is disposed at the rear end portion of the conveying device 17, and furthermore, a first ejection roller pair 26 normally transfers the transfer sheet to a second one on the rear side of the fixing device N25. Ejection roller pair 27
It is arranged so that it can be discharged to a tray or the like outside the machine.

A flapper 29 and an auxiliary flapper 30 are disposed between the first pair of discharge rollers 26 and the second pair of discharge rollers 2 and 7, and the paper discharged from the first pair of discharge rollers 26 is normally disposed. The transfer sheet is conveyed along the upper side of the flapper 29 at the solid line position, and the conveyance force swings the auxiliary flapper 30 in the direction of the arrow, and based on this, the detection arm 31 activates the optical sensor 32 to detect the passage of the transfer sheet. At the same time, it is discharged to the outside of the machine by a second pair of discharge rollers 27 that rotate normally.

In addition, during double-sided copying, the transfer sheet is partially ejected out of the machine by the normal rotation of the second ejection roller pair 27, as in the normal case, but the rear end of the transfer sheet is removed from the auxiliary flapper. 30, the detection arm 31
and the second discharge roller pair 2 due to the operation of the optical sensor 32.
7 is reversely operated, whereby the transfer sheet is guided by the left side of the auxiliary flapper 30 and the flapper 29 and introduced into the path 33. Therefore, during double-sided copying, the second discharge roller pair 27, flapper 29, W
The transfer sheet is re-fed by the I-assistant flapper 30, the detection arm 31, the optical sensor 32, and the warp #133. Furthermore, during multiple copying, the flapper 29 is switched to the dotted line position, and the transfer sheet discharged from the first discharge roller pair 26 is introduced into the path 33 by the guiding action of the right side of the flapper 29. There is. Therefore, during multiple copying, the transfer sheet is re-fed by the first discharge roller pair 26, the flapper 29, and the path 33. Then, the transfer sheet introduced into the path 33 is transferred to the registration roller via the sheet conveyance section 23, which has a pair of conveyance rollers 35, 36 and a lateral registration means 37 for aligning one side edge of the transfer sheet in the lateral direction to a reference position. versus 22
You will be guided to.

As described above, in the copying apparatus 1, when performing multiple copying or double-sided copying on the same transfer sheet, the image forming unit 2
The transferred sheet conveyed out through the fixing section 25 is introduced into the image forming section 2 again via a sheet refeeding means such as a flapper 29 and the sheet conveying section 23, and at that time, The horizontal positioning and vertical positioning of the transfer sheet are performed by the horizontal registration means 3, respectively.
7 and a pair of registration rollers 22 to align one side edge of the transfer sheet in the lateral direction and the leading edge of the transfer sheet at a prescribed position.

→ Problems to be Solved by the Invention Incidentally, in the copying apparatus 1 described above, the lateral positioning of the transfer sheet to be introduced into the copying section 2 again is performed using the cassettes 9a,
9b, the side edge of the transfer sheet in the t: state is set as a reference position, and the lateral registration means 37 operates to align the negative side edge of the transfer sheet to a prescribed position that is set in advance to match the reference position. Therefore, if the transfer sheet was correctly stored in the cassettes 9a and 9b and the transfer sheet was correctly supplied to the copying section 2 during the previous copying, the subsequent horizontal movement of the transfer sheet Although the misalignment is correctly corrected by the lateral registration means 37, the transfer sheet is introduced into the copying section 2 again. Even if the transfer sheet is stored correctly, the paper feed roller is 20g,
If the toner image is misaligned in some way before it is introduced into the copying section 2 via the toner transfer section 20b, the toner image will be misaligned and formed on the transfer sheet in the copying section 2 from the beginning. Thereafter, when the transfer sheet is corrected to the above-mentioned prescribed position by the tank resting means 37 for multiple copying, there is a drawback that the correction operation actually causes image deviation, and this also applies to laser beam printers.

B) Means for Solving the Problems The present invention ζ aims to solve the above-mentioned problems, and it is an object of the present invention to solve the above-mentioned problems. In an image forming apparatus configured to reintroduce the image-formed sheet that has been carried out through the image forming section into the image forming section, the sheet is placed on the sheet feeding path near the image forming section.・Providing a first detection means for detecting the lateral position of the sheet edge by scanning the detection unit in a direction that cuts the lateral sheet edge at right angles to the conveying direction, and also leading to the image forming unit again. A second lateral sheet end detecting means and a lateral position correcting means are provided in the sheet conveyance section up to, and based on the amount detected by the first detecting means, the sheet is adjusted to the lateral position of the sheet in the previous image forming process. The present invention is characterized in that the position of the seat is corrected by the above-mentioned lateral position correcting means so as to match the above.

It,) Function Based on the above-described configuration, first, when an image is formed on a sheet for the first time in the image forming section, the first detection means provided near the image forming section detects the The edge position of the sheet in the blooming direction forming a right angle is detected. Next, when the sheet is conveyed to the sheet lateral position correcting means of the sheet conveying section via the sheet refeeding means,
The position of the sheet is corrected by the position correction means and the second detection means so as to match the lateral position of the sheet detected by the first detection means, and then the sheet is introduced into the image forming section again. .

(F) Embodiments Hereinafter, embodiments embodying the present invention will be described with reference to the drawings.

1 and 2 show the transfer sheet 1 and the lateral position correction means 39 provided in place of the stacking register means 37 in the sheet conveying section 23 of the copying apparatus 1 (see FIG. 5) described above.
FIG. 3 shows a perspective view and a front view, respectively, of the position correction means 39.
is means for correcting the position of the transfer sheet in a direction perpendicular to its conveyance direction, and includes an upper roller 40a and a lower roller 40b that are pressed against each other. The upper roller 40a is rotatably supported by a shaft 41a, and the lower roller 40b is integrally fixed to the shaft 41b, and the shaft 41a of the upper roller 40a and the lower roller 40b
The shaft 41b connects to the front and rear side plates 1a of the copying apparatus 1 via bearings 42, . . . , respectively.

1b rotatably and slidably supported by each bearing 42.
, . . . and the collars 4 provided on each shaft 41a, 41b.
A compression spring 45, disposed between 3,...
・It is biased to the left in FIG. Further, the shafts 41a and 41b are respectively inserted into a block body 46 so as to be rotatable, and the block body 46 is connected to a connecting member 4 disposed in an upper portion thereof.
It comes into contact with a cam member 47 via 6a. The cam member 47 is of a type in which an inclined cam is formed on the circumference of the end of a cylindrical body. When the clutch 49 is turned on by a solenoid (not shown), the rotational force of the drive gear 50 is transmitted to the shaft 51 via the clutch 49 to rotate the cam member 47, and one rotation of the cam member 47 causes the block to be removed. The upper roller 40a and the lower roller 40b are connected via the body 46 to the spring 45,
It is moved in the left and right directions B and C (see Fig. 1) against the... Due to the regulating action, the central portion 47a of the inclined surface of the cam member 47 comes into contact with the roller member 46a, and the upper roller 40g and lower roller 40b
It is designed to be stopped at the center position of the left and right movement, that is, at the home position. Also, the shaft 4 of the lower roller 40b
A gear 55 is fixed to 1b, and an electromagnetic clutch 56
is turned on and the rotational force of the drive gear 57 is applied to the clutch 5.
6 to the shaft 59 and rotates the transmission gear 60, the gear 55 meshing with the gear 60 is rotated, thereby rotating the lower roller 40b, and the upper roller 40a and the lower roller 4Qb are rotated. The transfer sheet, which had been stopped with its leading end abutting against the contact portion, is now subjected to a conveyance action. Furthermore, as shown in Figure 1,
An optical sensor 61 (second detection means) consisting of a light-receiving section, so-called CCD 6lb, in which a planar light-emitting section 61a and a large number of light-receiving elements are arranged in parallel close to the contact portion between the upper roller 40a and the lower roller 40b. ), and the lateral position of the transfer sheet is detected by the cough light sensor 61. 1 is an upper guide plate for guiding the transfer rate toward the contact portion between the upper roller 40a and the lower roller 40b. It is designed to be integrally fixed to the 41m. Further, the reference numeral 36 is the lower roller of the conveyance roller pair explained in FIG.

FIG. 3 shows a detection means (a first
FIG. 4 is a perspective view showing an example of the arrangement of an optical sensor 65, which is a detection means for a photoreceptor 10 (a fifth detection means);
(see figure) and is arranged after the pair of registration rollers 22. In this embodiment, the optical sensor 65 is composed of a so-called photointerrupter, and the transfer sheet S passes between the light emitting part 65a and the light receiving part 65b of the optical sensor 65, and the light emitting part 65a
The light receiving portion 65b is integrally held by an arm 65c, and the arm 65C is rotatably supported by a pin 66 fixed to the main body of the copying apparatus. A groove 65d is provided in a part of the arm 65c, and this groove 65d is connected to the upper registration roller 2 of the registration roller pair 22.
A disc cam 67 integrally attached to 2a is sandwiched from both sides, and this disc cam 67 transfers the optical sensor 65 to the transfer sheet S.
Therefore, as the pair of registration rollers 22 rotate, the optical sensor 65 reciprocates in the direction of arrow Z around the pin 66.

Since this embodiment has the above configuration, when the copying operation is started by pressing the copy button (not shown), the transfer sheet S supplied from the cassette 9a or 9b passes through the pair of registration rollers 22, and then The lateral end of the sheet is scanned by an optical sensor 65. The electrical signal from the optical sensor 65 is sent to the calculation section of the microprocessor unit (MPU) that controls the copying machine 1, where the lateral position of the transfer sheet S is calculated and stored in the memory section. Preparations are made in the MPU to operate the position correction means 39 in response to the detected lateral position.

Here, the method for detecting the lateral position of the sheet S described above will be explained in more detail using FIG. 4.

In FIG. 4, reference numeral A indicates the ideal lateral end position of the transfer sheet 3 in the copying apparatus 1 of this embodiment, and the optical sensor 65 is shown at the top at the farthest position with respect to A. It is. Symbol B is a detection part of the optical sensor 65,
As is clear from the above description, the optical sensor 65 performs a reciprocating motion rightward in the figure from this position. Therefore, when the detection part B crosses the transfer sheet inward (to the left), the light from the optical sensor 65 is blocked, and when the detection part B crosses the transfer sheet to the outside (to the right), the light from the optical sensor 65 is opened. . and,
Since the tangential movement speed and stroke of the optical sensor 65 are known in advance, the transfer sheet S shown in 4-1 (al)
The passage time of the detection unit B when the detection unit B is at the ideal position A is known in advance, and this value is stored in the MPU. Therefore, when the sheet edge is at the position 4-1(b), the passing time of the detection unit B on the transfer sheet S is ideal [4-1
(al], and shorter than 1 when in position 4-1 (c). Therefore, in each case, the value of each sheet edge is compared with the ideal case value stored in the MPU. The position is detected.

Here, another embodiment of the present invention will be described with reference to 4-2 in FIG. 4, which is a detection method different from the above-mentioned detection method. The moving arrangement of 65 also differs from that shown in FIG. That is, the lateral movement of the optical sensor 65 is not caused by direct drive transmission from the registration rollers as shown in FIG. The configuration starts from the top position in FIG. To explain in more detail, since the home position and the ideal seat position are known in advance, the MPU stores the time from when the solenoid or clutch is turned on and the optical sensor 65 starts moving until the seat reaches the ideal position. However, this is the case of 4-2 (a+. Then, the time and 4
-2 (b).

(The position of each transfer sheet end can be detected by comparing the time detected when there is a sheet end in cl.

Furthermore, another embodiment of the present invention will be described with reference to 4-3 in FIG. It is designed to move.

This can be achieved by changing the position of the bin 66 and the shape of the cam 67 in the configuration of the optical sensor 65 shown in FIG.
Such an operation can be performed. The detection process is the same as in case 4-1 above, and since the rotation radius and rotation speed of the detection part of the optical sensor 65 and the ideal sheet edge position A are known in advance, The transit time a , / of the detection section of the optical sensor 65 is known in advance, and this value is stored in the MPU. Therefore, by comparing the detection times bb' and cc/ with the values, the end position of the transfer sheet in the beak direction can be detected in each case.

In addition, (4-1), (4-21, (4-
Each of the detection methods shown and explained in 3) can repeatedly detect the transfer sheet S multiple times during its passage, so by averaging these detection values, it is possible to determine the lateral end position of the transfer sheet with higher accuracy. can be detected.

Next, the transfer sheet S that has passed through the optical sensor 65 is subjected to a fixing action in the fixing section 25, and is transferred to the sheet conveying section 23 by a flapper 29 or the like for multiple copying or double-sided copying.
will be reshipped to. Thus, transcription sea! -S is the first
When the transfer sheet enters the lateral position correcting means 39 of the sheet conveying section 23 as shown by arrow A in the figure, the passage of the transfer sheet is detected by a sensor (not shown) immediately before the position correcting means 39, and based on the Even after the leading edge of the transfer sheet contacts the contact portion between the stopped old roller 40a and the lower roller 40b, the conveying action of the transfer sheet by the pair of conveying rollers 36 is continued for a predetermined time, and after the above-mentioned predetermined time IK8 has elapsed, the transfer sheet is The conveying operation of the pair of conveying rollers is stopped, so that the leading edge of the transfer sheet is moved to the upper roller 4. Oa and lower roller 4
While in contact with the contact portion of 0b, the transfer sheet is bent by an appropriate amount, that is, a loop is formed. Then, the conveyor roller pair 3
6 is rotated and the electromagnetic clutch 56 is turned on at the same time, the rotation of the drive gear 57 is transmitted to the gear 55 via the shaft 59 and the gear 60, the lower roller 40b starts rotating, and the transfer sheet is rotated. Conveyance is started while the loop is still formed by being held between the roller 40a and the lower roller 40b. At the same time, the spring clutch 49 is turned on, and the rotation of the drive gear 50 is transmitted to the cam member 47 via the shaft 51.
The rotation of the cam member 47 causes the roller member 46 to rotate.
The block body 46 is moved from its stop position, that is, the home position, in the C direction via a, and if necessary, to the rightmost end, and then moved in the B direction to the leftmost end, and from there again to the C direction.
The transfer sheet is conveyed while being moved in a direction perpendicular to the conveyance direction. At this time, due to the presence of the loop described above, the transfer sheet can be smoothly moved into the tank without applying any unreasonable force or deforming the transfer sheet. And the above transfer sheet S
When the transfer sheet S moves in the lateral direction, the lateral position of the transfer sheet S is checked by the optical sensor 61, and the lateral position of the transfer sheet S is detected by the optical sensor 65 and stored in the MPU. When the lateral position coincides with the lateral position of
The horizontal movement of the transfer sheet is stopped, and then the rotational conveyance action of the upper roller 40a and the lower roller 40b continues for a predetermined period of time, so that the transfer sheet is transferred from the sheet conveyance unit 23 to the registration roller pair with the horizontal position corrected. 22. After the transfer sheet is conveyed, the electromagnetic clutch 56 is disengaged and the rotation of each roller 40a, 40b is stopped, and the position correcting means 39 is reset to the central home position by the light shielding plate 52, optical sensor 53, etc. fX is returned to the seal, and the next transfer sheet S is placed in a standby state for position correction.

In each of the above embodiments, the optical sensor 61 is installed downstream of the upper roller 40a1 and the lower roller 40b with respect to the transport direction of the transfer sheet S, but it is of course possible to install the optical sensor 61 upstream. . Similarly, the installation position of the optical sensor 65 is preferably a position close to the photoreceptor lO as in the embodiment, but is not limited thereto, and may be installed downstream of the fixing section 25 or the like. Further, in the embodiments, an optical type sensor has been described, but it goes without saying that the sensor is not limited thereto.

As explained above, according to the embodiments of the present invention, in order to perform multiple image formation or double-sided image formation on the same transfer sheet, the transferred sheet that has been conveyed out through the image forming section is
In an image forming apparatus configured to re-introduce the transfer sheet to the image forming section via a sheet refeeding means such as a flapper and a sheet conveyance section, the transfer sheet is placed on the conveyance path of the transfer sheet near the image forming section. a first detection means for detecting a lateral position perpendicular to the conveyance direction of the transfer sheet, and a transfer sheet lateral position correction means and a second detection means are provided in the sheet conveyance section up to the image forming section; The position correction means corrects the lateral position of the transfer sheet to be introduced into the image forming section again so that it matches the lateral position of the transfer sheet in the previous image forming process detected by the detection means. Therefore, when performing multiple image formation or double-sided image formation on the same transfer sheet, when forming the first image on the transfer sheet S, the transfer sheet supplied from the cassette! Even if the lateral position of the transfer sheet deviates slightly from the normal position, the lateral position of the transfer sheet is corrected and controlled so that image formation is performed twice based on this position, and the transfer sheet is transferred to the image forming section again. As a result, there may be image misalignment between the image formed in the first image forming process and the image formed in the same process from the second time onwards, or when forming images on both sides of the same transfer sheet. The phenomenon of image blurring on the front and back surfaces can be effectively prevented with a simple configuration to the extent that it is hardly noticeable to the naked eye.

In addition, since the detection section of the first detection means is configured to scan the sheet in the cutting direction to detect the position of the sheet edge, the detection section can be a simple structure such as a photointerrupter. Fortunately, the structure and operation are both simple, and it has become possible to easily and inexpensively obtain a sheet on which a high-quality image is formed.

(G) As described in detail, according to the present invention, the detection unit scans the sheet conveyance path in the vicinity of the image forming section in a direction perpendicular to the sheet conveyance direction and across the lateral sheet edge. A first detecting means for detecting the lateral position of the sheet edge is provided, and a second lateral sheet edge detecting means and a lateral position correcting means are provided in the sheet conveying section until reaching the image forming section again. Based on the amount detected by the first detection means, the position of the sheet is corrected by the clear direction position correction means so that the sheet matches the lateral position of the sheet in the previous image forming process. When the sheet is introduced into the image forming section again, the positional deviation of the sheet can be corrected accurately.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of a transfer sheet lateral position correcting means applied to the image forming apparatus of the present invention, FIG. 2 is a front view thereof, and FIG. 3 is a detection of the position of the transfer sheet in the paddle direction. FIG. 4 is a diagram illustrating a method for detecting a position in the lateral direction of a transfer sheet, and FIG. 5 is a schematic diagram of an image forming apparatus to which the present invention can be applied. DESCRIPTION OF SYMBOLS 1... Image forming part (W, copying device), 2... Image forming part (l ear part), 23... Sheet conveyance part, 3
9... Sheet tank direction position correction means, 61... Second detection means (optical sensor), 65... First detection means (optical sensor), S... Sheet (transfer sheet)
.

Claims (3)

[Claims] (1) In an image forming apparatus configured to reintroduce an image-formed sheet that has been carried out through an image forming section into the image forming section in order to perform multiple image formation or double-sided image formation on the same sheet. , a first sensor for detecting the lateral position of the sheet edge by scanning the detection unit on the sheet conveyance path near the image forming section in a direction perpendicular to the sheet conveyance direction and across the lateral sheet edge;
Further, a second lateral sheet edge detection means and a lateral position correction means are provided in the sheet conveying section leading to the image forming section again, and the amount detected by the first detection means is An image forming apparatus according to the present invention, wherein the lateral position correcting means corrects the position of the sheet so that the lateral position of the sheet matches the lateral position of the sheet in the previous image forming process. (2) The first detection means is an optical sensor consisting of a photointerrupter, and the detection section of the optical sensor detects the width of the sheet depending on the time from the time when the sheet edge crosses the sheet edge to the sheet edge to the sheet edge. An image forming apparatus according to claim 1, wherein the image forming apparatus detects a directional position. (3) The image forming apparatus according to claim 2, wherein the first detection means rotates in the sheet advancing direction while crossing the sheet lateral end.