JPH07110747B2 - Image forming device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image forming apparatus such as a copying machine provided with a conveyance path for double-sided multiplexing.

(Prior Art) Conventionally, this type of copying apparatus is provided with a transport path for transporting a once-transferred transfer sheet to a copying section again in order to perform multiplex copying or double-sided copying. As shown in FIG. 5, conveying rollers 52 and 53, each having a plurality of rollers 51 fixed to a shaft 50 at predetermined intervals, are arranged in this conveying path, and a driven roller 54 and a supporting plate 55 are attached to the roller 51. Being crimped by. Then, the conveyance rollers 52 and 53 rotate in the direction of the arrow upon receiving drive transmission from the main body drive source, and convey a transfer sheet (not shown) in cooperation with the driven roller 54.

At this time, the transfer sheet is conveyed in the conveying direction (vertical direction)
If the dimension is smaller than the interval A between the transport rollers 52 and 53, the transport is impossible, and the direction orthogonal to the transport direction (lateral direction)
Is shorter than the width B from the reference position XX at the end of the sheet to the second driven roller 54, the transfer sheet is conveyed by only one roller 51 of the conveying rollers 52, 53. . As a result, the transfer sheet conveyance direction by the conveyance rollers 52, 53 becomes unstable, and it becomes difficult to convey the transfer sheet straight.

Therefore, the size of the transfer sheet that can be transported when performing double-sided or multiple copying must be at least larger than the dimensions A and B shown in FIG. 5, and the largest value of A and B in the transport path. Is the minimum size of a transfer sheet that can be double-sided or multiplex as a copying machine. If a transfer sheet smaller than this size is sent to the transport path,
It becomes impossible to carry or becomes defective, and jam occurs.

Therefore, in the conventional model, in order to limit the size of the transfer sheet for double-sided or multiplex copying, the sheet feeding method is limited to only cassette sheet feeding that can detect the size of the transfer sheet, and the transfer is performed based on the cassette size detection information. The size of the sheet is obtained, and double-sided or multiple copying of the transfer sheet having the minimum size or smaller is prohibited.

(Problems to be Solved by the Invention) However, in the case of such a conventional technique, the size of the transfer sheet is detected by the cassette, and it is determined whether or not the sheet can be double-sided or multiplex copied. Therefore, it has the following problems. That is, a transfer sheet of a nonstandard size without a cassette has a disadvantage that it cannot be duplicated or duplicated even if it exceeds the above-mentioned minimum size capable of being duplicated or duplicated. Further, in manual feeding, since the size of the transfer sheet is unknown, there is a problem that double-sided or multiple copying cannot be performed from manual feeding even if the transfer sheet has a standard size. further,
Since the size of the transfer sheet is judged by the size signal of the cassette, if the size of the cassette is erroneously detected or a transfer sheet of a size that cannot be duplicated on both sides or multiple sheets is erroneously stacked in the cassette, a jam of the conveyance path is detected. There was a problem that there was a risk of leading to.

Therefore, the present invention has been made in order to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a sheet material having a minimum size capable of double-sided or multiple copying without using a cassette. An object of the present invention is to provide an image forming apparatus capable of performing double-sided or multiple copying, and capable of preventing a jam even when both or multiple copying is designated with a sheet material having a minimum size or less.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention includes a conveyance path for conveying the sheet material on which an image is formed to the image forming unit again, and an image capable of forming a double-sided image or multiple images. In the forming apparatus, a unit for detecting the size in the length direction and the size in the width direction of the sheet material fed from the supply unit is provided, and the size of the sheet material detected by the detection unit is normal in the re-conveyance path. For sizes other than the specified size that can be transported,
Even if a double-sided or multiple image forming operation is designated, the sheet material is not conveyed to the conveyance path.

The predetermined size is a size that is equal to or greater than the interval in the sheet material length direction and the interval in the width direction of the transport rollers in the transport path.

(Operation) In the present invention, when the size of the sheet material detected by the detection means is other than the predetermined size, the sheet material is conveyed to the conveyance path even if the double-sided or multiple image forming operation is designated. Try not to.

(Examples) The present invention will be described below based on illustrated examples.

FIG. 1 shows a copying machine as an embodiment of the image forming apparatus according to the present invention. The copying apparatus 1 has a copying apparatus main body 3 having a copying unit (image forming unit) 2 built-in, and the copying apparatus main body 3 includes an original placing table 5, a light source 6, a lens system 7, two cassettes 9a, The copying section 2 is provided with a cylindrical photoconductor 10 and the like, which is provided with 9b and the like, and is approximately in the center of the apparatus main body 3. Then, in the vicinity of the periphery of the photoconductor 10, two developing devices 11a and 11b each containing a toner of a different color, a cleaner 12 and a primary charging device 13, and a transfer device installed at the front end portion of the transfer device 17 are provided. A charging charger 15 and a separating charger 16 are provided. In addition, paper feed rollers 19a and 19b are disposed in the cassettes 9a and 9b installed in the supply unit, and a transfer sheet S serving as a sheet material is registered via a pair of conveyance rollers 20a and 20b and paths 21a and 21b, respectively. Laura pair
The transfer sheet which is to be guided to the sheet 22 and which is subjected to multiple copying or double-sided copying via the sheet conveying section 23 disposed below the apparatus main body 3 is the registration roller pair 22.
You will be guided to. In addition, the transfer device 17
A fixing device (fixing section) 25 is provided at the rear end portion of the
Further, on the rear side of the fixing device 25, a first discharge roller pair 26 is arranged so as to discharge the transfer sheet to a tray or the like outside the machine via the second discharge roller pair 27. And the first
A flapper 29 and an auxiliary flapper 30 are disposed between the second discharge roller pair 26 and the second discharge roller pair 27, and normally the transfer sheet discharged from the first discharge roller pair 26 is the flapper at the solid line position. When the auxiliary flapper 30 is conveyed along the upper side of 29, the auxiliary flapper 30 is swung in the direction of the arrow by the conveying force, and the detection arm 31 operates the optical sensor 32 based on the conveyance force to detect the passage of the transfer sheet and rotate normally. The pair of discharge rollers 27 of FIG. During double-sided copying, the transfer sheet is partially discharged outside the apparatus by the forward rotation of the second discharge roller pair 27 as in the normal state, but the trailing edge of the transfer sheet is the auxiliary flapper.
When it leaves 30, the second discharge roller pair 27 is reversely operated by the operation of the detection arm 31 and the optical sensor 32, and the transfer sheet is guided by the left side portions of the auxiliary flapper 30 and the flapper 29 to the path 33. It is supposed to be introduced. Therefore, during double-sided copying, the second discharge roller pair is used.
The transfer sheet is re-fed by 27, flapper 29, auxiliary flapper 30, detection arm 31, optical sensor 32, and path 33. 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 guide action of the right side portion of the flapper 29. There is. Therefore, at the time of multiple copying, the transfer sheet is re-fed by the first discharge roller pair 26, flapper 29 and path 33. Then, the transfer sheet introduced into the path 33 has a pair of conveying rollers 35, 36 and a sheet conveying section 23 having a lateral registration means 37 for aligning one lateral end of the transfer sheet at a reference position.
It is configured to be guided to the registration roller pair 22 via.

In this copying apparatus 1, the transfer sheet is placed on the upper cassette.
9a, the lower cassette 9b, and the manual feed tray 38 can be used for manual paper feed.

Further, in the feeding path of the transfer sheet S, it is detected whether the transfer sheet S is normally fed and fed to the registration roller 22, and in front of the registration roller 22 to correct the skew feeding of the transfer sheet S. In order to detect the passage timing of the copy sheet S for determining the stop timing of the transport rollers 20a and 20b for forming a loop on the transfer sheet S, the paper detection means including the sensor arm 40 and the optical sensor 41 is
It is installed just before the registration roller 22. The paper detection unit also serves as a unit that detects the size of the transfer sheet S. As shown by the solid line in FIG. 1, the sensor arm 40 blocks the optical path of the optical sensor 41 when there is no transfer sheet S, but when there is a transfer sheet S, two points are shown in FIG. As indicated by the chain line, the sensor arm 40 tilts,
The optical path of the optical sensor 41 is opened. By detecting the entry timing and the passage end timing of the transfer sheet S by this detection means, the length of the transfer sheet S in the traveling direction is detected from the feed speed of the transfer sheet S which is known in advance.

Further, on the side of the detection means, a reflection type optical sensor 42 as a detection means for detecting the size of the transfer sheet S in the width direction, that is, the lateral direction, is located at a position orthogonal to the feeding direction of the transfer sheet S. Is installed. This reflection type optical sensor 42 is installed on both sides of the transfer sheet S at the minimum width of the transfer sheet S capable of multiple copying, so that
When the transfer sheet S having a size capable of multiple copying is being fed, the transfer sheet S passes over the optical sensor 42, so that the reflected light is incident on the optical sensor 42 to prevent the transfer sheet S from passing. Transfer sheet S that can be detected and can be duplicated on both sides
It can be seen that it is. Further, when the size of the transfer sheet S is double-sided, and the small size in which multiple copying is impossible or difficult,
Since the transfer sheet S does not pass over the optical sensor 42, the reflected light does not enter the optical sensor 42, and it can be detected that the transfer sheet S is double-sided and has a size unsuitable for multiple copying.

FIG. 4 is a block diagram showing a control system. In the figure,
Reference numerals 41 and 42 are the optical sensor and the reflection type optical sensor for detecting the size of the transfer sheet S, 43 is a control circuit, and 44 is a solenoid for driving the flapper 29 and the auxiliary flapper 30.

With the above configuration, the copying machine according to this embodiment operates as follows. That is, when the user instructs double-sided copying or multiple copying using an operation panel (not shown), the transfer sheet S is fed from either the paper feed cassettes 9a, 9b or the manual feed tray 38, and the above-mentioned transfer sheet S is fed. An image is formed as described above. At that time, the size of the transfer sheet S is detected by the optical sensors 41, 42, and the optical sensors 41, 42 are detected.
A detection signal is sent from 42 to the control circuit 43. Control circuit 43
Determines whether or not the detected size of the transfer sheet S is equal to or larger than the minimum size that allows double-sided and multiple copying based on the data stored in advance. If the size of the transfer sheet S is smaller than the minimum size, the control circuit 43 controls the solenoid 44 even if double-sided or multiple copying is designated.
Is driven to bring the flapper 29 and the auxiliary flapper 30 into the state shown by the solid line in FIG. 1, and the transfer sheet S for which single-sided copying has been completed is discharged as it is onto a paper discharge tray (not shown). Also,
When the transfer sheet S has a size that allows double-sided copying or multiple copying, the transfer sheet S is conveyed again to the copying section 2 via the flapper 29, the auxiliary flapper 30, and the sheet conveying section 23.
Perform double-sided or multiple copying.

Further, in the above embodiment, the one using the optical sensor as the size detecting means has been described, but the present invention is not limited to this, and a reading element such as a CCD for reading the size of the transfer sheet may be used. Of course, it is possible to change.

(Effects of the Invention) The present invention has the above-described configuration and operation, and a sheet material that exceeds the minimum size capable of performing double-sided and multiplex image formation can be double-sided and double-sided by manual sheet feeding as well as the cassette. Amorphous sheet material can be used depending on the paper, and the range of use for double-sided and multiple image formation is expanded. Moreover, since the length direction size and the width direction size of the sheet material are directly detected, if the sheet material size is double-sided, and the size cannot be reliably conveyed for multiple image formation,
You can always discharge with an image formed on one side,
It is possible to reliably prevent the occurrence of a jam or the like that occurs when the sheet material is transferred to both sides or the multi-passage path due to the false detection by the cassette or the mixing of the sheet material of the defective size.
Further, since the sheet material size detecting means detects the lengthwise size and the widthwise size of the sheet material to determine whether or not the normal conveyance is possible as described above, it does not have an intermediate tray. Therefore, it is effective for an image forming apparatus that performs double-sided or multiple image formation.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of an image forming apparatus according to the present invention, FIG. 2 is a partially enlarged sectional view showing an essential part, FIG. 3 is a broken perspective view showing the essential part, and FIG. FIG. 5 is a block diagram showing a control system, and FIG. 5 is a perspective explanatory view showing a size of a double-sided sheet material capable of multiple copying. Explanation of code 2 …… Copier, 23 …… Sheet transport 41,42 …… Optical sensor 43 …… Control circuit

Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location G03G 21/00 520 (72) Inventor Masashi Ohashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yasunori Maeda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yasuyoshi Yamamoto 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Invention Tatsuya Shiratori 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Naoki Okuda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Akiyoshi Kimura Tokyo 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Toshihiko Kusunagi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Atsushi Kubota Shimomaruko, Ota-ku, Tokyo 3-30-2 Canon Inc. (72) Inventor Michio Koike 3-30-2 Shimomaruko, Ota-ku, Kyoto Canon Inc. (56) Reference JP 61-221042 (JP, A) JP 62-175340 (JP, A) JP 62-10667 (JP) , A)

Claims (2)

[Claims] 1. An image forming apparatus having a conveyance path for conveying an image-formed sheet material to an image forming section again, capable of forming double-sided images or multiple images, in the longitudinal direction of the sheet material fed from a supply section. If the size of the sheet material detected by the size detecting means and the size in the width direction is other than a predetermined size that allows normal conveyance in the re-conveyance path, double-sided or multiple image formation is performed. An image forming apparatus characterized in that a sheet material is not conveyed to the conveying path even if an operation is designated. 2. The predetermined size is a size which is equal to or larger than a distance in a sheet material length direction and a distance in a width direction between the conveyance rollers in the conveyance path.
The image forming apparatus according to the item.