JP3335493B2 - Jam detection device for copier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine capable of copying a large-sized document.

[0002]

2. Description of the Related Art An original is illuminated and scanned, an electrostatic latent image is formed on a photoreceptor by reflected light from the original, the electrostatic latent image is visualized as a toner image, and the toner image is formed on a copy sheet. 2. Description of the Related Art An electrophotographic copying machine adapted to heat and fix is widely used. As such a copying machine, there is provided a copying machine capable of copying a document of a large size, for example, Japanese Industrial Standards A row 0 (hereinafter referred to as "A0 version").

A copying machine capable of copying a large-sized document is provided with a reading mechanism capable of reading a large-sized document, and a transport mechanism for transporting a large-sized copy sheet corresponding to the document. Have.

[0004]

When a large copy sheet is conveyed, the jam is detected even if a part of the copy sheet is in a conveyance failure state (so-called jam) because the copy sheet is large. However, there is a problem that the jam detection may not be performed until the entire conveyed copy sheet is entangled with the conveyance roller.

As described above, in a conventional copying machine that conveys a large-sized copy sheet, the problem of jam clearance that may occur due to a large copy sheet being conveyed has not been sufficiently solved. Therefore, the present invention is a jam detecting apparatus for a copying machine capable of conveying a large-sized copy sheet, and when a conveyance failure occurs in a part of the copy sheet during conveyance, a jam detection signal is quickly transmitted. Is to provide a jam detecting device for a copying machine that can output the same.

[0006]

According to the first aspect of the present invention,
It feed transportable copy sheet along a transport path, a jam detection for the copier system in which the transfer of the image formed by an electrophotographic system to a copy sheet being fed, fixing the transferred image on the copy sheet an apparatus, provided in the transfer route, a discharge sheet detecting means for outputting a signal when the copy sheet is present at that position, provided in the vicinity of the output sheet detecting means as viewed in the conveying direction of the copy sheet, the copy Sheet transport direction
Small and are arranged at predetermined intervals in the cross direction, and outputs a pulse in accordance with the movement of the copy sheet that exist <br/> resident in conveying route
And Kutomo two pulse output means, said being a signal from the output sheet detecting means output, and pulse a predetermined time or more from any one or more of the two pulse output means based on the fact that not output And a jam discriminating means for discriminating that a conveyance failure of the copy sheet has occurred. Claim
According to the invention described in 2, the pulse output means is provided three,
One is the center of the transport path, the other two are both ends of the transport path
2. The device according to claim 1, wherein
It is a jam detection device for a copying machine as described in the above.

[0007]

According to the present invention, the presence of the copy sheet is detected by the discharged sheet detecting means. Further, it is determined whether or not the existing copy sheet is moving, that is, whether or not the copy sheet is satisfactorily conveyed, based on the output pulse of the pulse output means. Therefore, when a copy sheet exists but the copy sheet has not moved, it can be determined that a conveyance failure of the copy sheet has occurred. As a result, particularly when the copy sheet is a long sheet, the jam detection of the copy sheet can be performed more quickly and accurately than in the related art. Therefore, it is possible to prevent a long copy sheet from being crumpled in the copying machine or a jam in a bad state such as being entangled with the rollers.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments will be described below in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view schematically illustrating an internal configuration of a copying machine according to an embodiment of the present invention, FIG. 2 is a perspective view illustrating an external configuration, and FIG. 3 is a perspective view illustrating the external appearance of the copying machine during copying. FIG. This copying machine is for obtaining a copy image of a large size original such as A0 size. In this copying machine, while the original is being conveyed, the surface of the original is illuminated and scanned by an optical system fixedly arranged, and an image is formed based on the illuminated scanning.

Referring to FIG. 1, a copying machine main body 1 is provided with caster wheels 2 at the bottom so that it can move freely. Referring to FIG. 1 to FIG.
A document transport unit 10 for transporting the document 9 along a document transport path 41 formed on the upper surface of the copying machine body 1
Is provided. A discharge port 54 from which the sheet on which the toner image is transferred is discharged is opened in the front surface 1a of the copying machine body 1. The sheet discharged from the discharge port 54 is
As shown in FIG. 3, while being guided by the guide member 91, the distal end of the copier body 1 is dropped with its tip downward, and is sequentially accommodated in the pocket 92 formed by the front cover 5 along the front surface 1a of the copying machine main body 1 through the introduction opening 93. It has become.
At the end of the upper surface of the copying machine body 1, an operation unit 100 provided with switches, keys, and the like for performing various settings related to copying is provided.

Referring to FIG. 1, the lower part of the copying machine main body 1 from the center in the height direction is provided with three upper, lower and middle roll sheets 4A, 4B, 4C wound in a roll shape. Is housed. These roll sheets 4A, 4B, 4C
They are wound on supply reels 51, 52, 53, respectively. Examples of the types of the roll sheets 4A, 4B, 4C include plain paper, film, and tracing paper. Also, at the center of the copying machine body 1,
For example, a bypass conveyance path D4 is provided for supplying cut sheets, such as A0 size to A4 size, cut to a predetermined length in advance through the manual paper feed unit 30 on the front surface 1a of the copying machine body 1.

The upper roll sheet 4A includes the supply reel 51, the paper feed roller 61, and the conveyed roll sheet 4A.
A first leading edge detection switch 71 that detects the leading edge of the sheet, a transport roller 62, a cutter mechanism 80, a transport roller 63, a second leading edge detection switch 72 that detects the leading edge of each of the conveyed sheets 4A, 4B, 4C, and 4D. And a first transport path D1 to the photosensitive drum 20 via the transport rollers 33 in order.
Conveyed along.

The middle roll sheet 4B is supplied with a supply reel 5
2. Paper feed roller 64, third leading edge detection switch 73 for detecting the leading edge of rolled sheet 4B being transported, transport roller 62, cutter mechanism 80, transport roller 63, second leading edge detection switch 72, and transport roller 33 Sequentially through
The sheet is transported along a second transport path D2 that reaches the photosensitive drum 20. The path after the transport roller 62 is common to the first transport path D1.

The lower roll sheet 4C is supplied with a supply reel 5
3. Paper feed roller 65, fourth leading edge detection switch 74 for detecting the leading edge of rolled sheet 4B being transported, transport roller 62, cutter mechanism 80, transport roller 63, second leading edge detection switch 72, and transport roller 33 Sequentially through
The sheet is conveyed along a third conveyance path D3 that reaches the photosensitive drum 20. The path after the transport roller 62 is common to the first transport path D1.

The bypass conveying path D4 is provided with a fifth leading edge detection switch 75 for detecting the leading edge of the cut sheet 4D introduced from the manual sheet feeding unit 30, and a sliding contact plate (not shown). Separating roller 3 that separates cut sheets by sliding contact (separates one by one)
2. A path leading to the photosensitive drum 20 via the sixth leading edge detection switch 76 for detecting the leading edge of the cut sheet to be transported, the registration roller 39, the second leading edge detection switch 72, and the transport roller 33 in order. is there. The path after the second leading edge detection switch 72 on the bypass conveyance path D4 is common to the first conveyance path D1.

The above-mentioned cutter mechanism 80 cuts the roll sheets 4A to 4C between the long fixed blade 81 extending in a direction perpendicular to the transport direction of the roll sheets 4A to 4C and the fixed blade 81. And a rotary blade 82 that performs the rotation. The document conveying section 10 sets the conveying direction to the forward direction R1 or the reverse direction R.
2, and the original 9 is conveyed. The image forming operation is performed when the document is transported in the forward direction R1. When multiple copies are made from the same original,
The document transport unit 10 transports the document 9 by alternately switching the transport direction between a forward direction R1 and a reverse direction R2. On the upper surface of the copying machine main body 1, the above-described document conveying path 41 is formed upstream of the document conveying section 10 in the forward direction R <b> 1 to a position protruding from the upper surface of the copying machine main body 1.

The document transport section 10 includes a first document edge detection switch 11, a first transport roller 12, a second document edge detection switch 16, a second transport roller 14, And the third transport roller 15 are sequentially arranged. The first conveyance roller 12 starts to be driven when the first document end detection switch 11 is turned on from off and detects the leading end of the document 9 (the end on the downstream side in the forward direction R1). The second transport roller 14 is provided at a position facing the transparent plate 13 for slit exposure of the original 9, and brings the original 9 into close contact with the transparent plate 13. The third transport roller 15 discharges the exposed document 9.

The second document end detection switch 16
Is switched from off to on when the original 9 is conveyed in the forward direction R1, so that the original 9
Detect the tip of This second document end detection switch 16
Is turned on, conveyance of the roll sheet 4A, 4B or 4C (hereinafter, the roll sheet 4A, 4B or 4C conveyed for copying is simply referred to as "roll sheet 4") is started, and the As a result, the conveyance of the document and the roll sheet 4 is synchronized.

Further, the first document end detection switch 11
Is switched from on to off when the original 9 is conveyed in the forward direction R1, so that the original 9
Detect the rear end of At a predetermined timing after a lapse of a predetermined time from the timing of this detection, the cutter mechanism 80 is driven, and the roll sheet 4 is cut. In the present embodiment, the corona discharger 2 for transfer is
4 (transfer position 20b), the length of the transport path of the roll sheet 4 from the first original edge detection switch 11 to the original exposure position 44 is longer than the length of the original transport path of the photosensitive drum 20. From the transfer position 20b to the transfer position 20b. Thus, an image corresponding to the rear end of the document 9 can be formed on the rear end of the roll sheet 4 obtained by cutting at the above timing.

The second document end detection switch 16
Switches from on to off when the document 9 is conveyed in the reverse direction R2, thereby detecting the rear end of the document 9 conveyed in the reverse direction R2. When the leading edge detection switch 16 is turned off, the driving of the transport rollers 12, 14, 15 is stopped. At this time, the leading end of the document 9 is held between the transport rollers 12, and is ready for the next copy operation. Reference numeral 8 denotes a reversing member for reversing the direction of the original to prevent the original 9 from dropping behind the copying machine body 1.

In connection with the transparent plate 13, a light source 17 for illuminating the original surface of the original 9 is fixedly arranged. The light from the light source 17 is applied to the surface of the document via the transparent plate 13. Then, the reflected light from the surface of the document 9 is guided by the selfoc lens 18 to the surface of the photosensitive drum 20 provided substantially at the center of the copying machine main body 1. The photosensitive drum 2 before being exposed by the light from the selfoc lens 18
0 is uniformly charged by the charging corona discharger 21. Therefore, an electrostatic latent image corresponding to the original image is formed on the surface of the photosensitive drum 20 after the exposure. This electrostatic latent image is visualized into a toner image by the developing device 22. This toner image is guided to the vicinity of the transfer corona discharger 24 by rotating the photosensitive drum 20 in the direction of the arrow 23.

On the other hand, the transport routes D1, D2, D3 or D
The sheet 4 guided to the photoconductor drum 20 from the photoconductor 4 is guided to the vicinity of the transfer corona discharger 24 while being in contact with the surface of the photoconductor drum 20. The toner image on the surface of the drum 20 is transferred to the sheet 4. The sheet 4 to which the toner image has been transferred is
The photosensitive drum 20 is separated from the surface of the photosensitive drum 20 by corona discharge in the separating corona discharger 25, and further guided to the fixing device 35 through the conveyance path 34. In the fixing device 35, the toner is fixed on the surface of the sheet 4 by heating and pressing the sheet 4 between the heat roller 37 and the pressure roller 38. The sheet 4 on which the toner has been fixed is discharged from the discharge roller 36 to the outside of the copying machine 1 via the discharge detection switch 55, and is stored in the pocket 92 via the guide member 91 as described above. On the other hand, the toner remaining on the surface of the photosensitive drum 20 after the transfer of the toner image is removed by the cleaning device 26, and the preparation for forming the next electrostatic latent image is made.

A guide auxiliary plate 94 is disposed above the guide member 91. This guide auxiliary plate 94
Is a stay 9 attached to the front surface 1a of the copying machine body 1.
5, the guide attitude of guiding the sheet hanging down and ejected forward of the guide member 91 to the pocket 92 together with the guide member 91 by the rotation (indicated by a dashed line in FIG. 1). And a storage posture (shown by a solid line in FIG. 1) held by the stay 95.

The photosensitive drum 20, developing device 22, transfer corona discharger 24 and the like constitute an image forming means. In this embodiment, a main motor MM for driving the image forming unit, a paper feeding motor DM for driving a roller group for feeding the sheets 4A to 4D, and a heat roller of the fixing device 35 37 and pressure roller 38
Fixing motor FM for driving the like and the like, the document conveying section 10
And a document feed motor OM for driving the document feeder.

FIG. 4 is a plan view showing the configuration near the discharge port 54 in the copying machine of the present embodiment. In FIG. 4, 3
Reference numeral 6 denotes a discharge roller. The copy roller on which the toner image is fixed by the fixing device 35 (see FIG. 1) is discharged in the sheet discharge direction by the discharge roller. A discharge detection switch 55 is provided upstream of the discharge roller 36 when viewed in the sheet discharge direction (conveying direction). The discharge detection switch 55
This switch is turned on when a copy sheet exists, and turned off when the copy sheet does not exist.

In the vicinity of the position of the discharge detection switch 55, pulse output units 230, 231, 232 are provided. In this embodiment, three pulse output devices are provided,
The three pulse output units 230, 231, 232 are arranged at predetermined intervals in a direction orthogonal to the copy sheet transport direction. More specifically, the pulse output device 230 is disposed substantially at the center of the copy sheet in the conveying direction near the discharge detection switch 55, and the pulse output devices 231 and 232 are in contact with both ends of the copy sheet. Are located in

FIG. 5 is an illustrative view showing a configuration of a jam detecting device in the copying machine according to the present embodiment. As shown in FIG. 5, each of the pulse output units 230, 231, and 232 includes a rotating disk 233 and a light emitting / receiving element pair 234. Each of the rotating disks 233 is rotatably disposed at a position where the peripheral surface thereof is in contact with a copy sheet to be conveyed on the conveying path. Therefore, each rotating disk 233 rotates as the copy sheet passes through the transport path. A number of slits are formed in the peripheral portion of the rotating disk 233 radially with respect to the center of rotation and at equal intervals. The light-emitter / light-receiving element pair 234 is provided around the rotating disk 233.
The light emitted from the light projecting element is provided to the light receiving element through the slit of the rotating disk 233.

With this configuration, the copy sheet is transported along the transport path, and the rotating disk 233 rotates as the copy sheet moves. In the light emitting / receiving element pair 234, light from the light emitting element to the light receiving element is transmitted by the slit or cut off at a portion other than the slit as the rotating disk 233 rotates. Therefore, the output of the light receiving element is a pulse signal in response to receiving or not receiving light. This pulse signal is output only when the copy sheet is being moved.

The output pulses of the pulse output units 230, 231, 232 are applied to a jam discriminating circuit 235. The signal of the discharge detection switch 55 is also transmitted to the jam determination circuit 23.
5 given. In the jam determination circuit 235, the output state of the discharge detection switch 55 and the three pulse output units 23
Jam determination is performed based on the presence or absence of a pulse signal provided from 0, 231, 232. When it is determined that a jam has occurred, a jam output is derived.

FIG. 6 is a diagram showing the jam discriminating circuit 235 shown in FIG.
6 is a timing chart for explaining a method of determining a jam in FIG. Referring to FIG. 6, jam determination circuit 23
5, any of the three pulse output units 230, 231, and 232 when a high-level signal is supplied from the discharge detection switch 55, that is, when the discharge detection switch 55 detects the presence of a copy sheet to be discharged. If no pulse is given for a certain period of time from one or more, a jam output is derived.

When the copy sheet to be transported is very long in the transport direction, it takes a very long time to detect the jam of the copy sheet only by the discharge detection switch 55. This is because when the jam detection is performed only by the discharge detection switch 55, it is possible to determine that a jam has occurred when the discharge detection switch 55 is on for a time required for the copy sheet to pass through the discharge detection switch 55. Therefore, it is possible to determine that a jam has occurred for the first time when the high-level signal is continuously input from the discharge detection switch 55 for a relatively long time. However, this requires too much time for jam detection.

Therefore, in the case of this embodiment, any one or more of the pulse output units 23 during the period when the discharge detection switch 55 is outputting a signal indicating that a copy sheet exists.
When no pulse is output from 0, 231, 232 for a certain period of time, it is immediately determined that a jam has occurred. This enables quick jam detection. In addition, it is possible to prevent a long copy sheet from being crumpled in the conveyance path or a jam in a severe state such as being entangled with the discharge roller 36 or the like.

In this embodiment, the pulse output device is
Three pieces are arranged in a direction orthogonal to the conveying direction of the copy sheet. One is provided at the center in the transport direction, and the other two are provided at the right and left ends in the transport direction. For this reason, when a relatively wide copy sheet of a large size is conveyed, the jam detection of the copy sheet can be performed correctly and quickly.

This is because when the width of the copy sheet is large,
Even if the conveyed copy sheet is conveyed correctly in the center in the conveyance direction, the right end or left end portion of the copy sheet may be wavy or stuck, resulting in conveyance failure. In other words, if the copy sheet is wide,
In the width direction, the conveyance state is slightly different at the right end, the center portion, and the left end, and the jam of the copy sheet first occurs locally, and the jam sometimes leads to the jam of the entire copy sheet.

Therefore, in this embodiment, a plurality of pulse output devices are arranged at predetermined intervals in a direction orthogonal to the copy sheet conveyance direction, so that a locally occurring copy sheet jam can be quickly detected. Thus, when a wide copy sheet is conveyed, even when a copy sheet conveyance failure occurs locally, it can be quickly detected, and before the entire copy sheet becomes jammed in a severe state, the conveyance device can be used. Can be stopped.

In the present invention, the above-described embodiment can be modified as follows. A configuration for detecting a jam of a copy sheet that is long in the transport direction is possible with the discharge detection switch 55 and one pulse output device. When only one pulse output device is used, the pulse output device may be provided near the discharge detection switch 55 or may be provided at a position separated from the discharge detection switch 55 by a predetermined distance in the transport direction. Further, the position where the pulse output device is provided may be any position, such as the center position or the end position, when viewed in the direction orthogonal to the transport direction.

On the other hand, when a plurality of pulse output devices are used, the discharge detection switch 55 can be omitted. For example, when two pulse output devices are used, if the copy sheet is satisfactorily conveyed, pulses are output from the two pulse output devices simultaneously. However, when a local jam or a jam of the entire sheet occurs, a pulse is not output from one or both of the pulses output from the plurality of pulse output devices. Therefore, the jam of the copy sheet can be detected thereby.

Further, the plurality of pulse output devices may not be arranged at predetermined intervals in the direction orthogonal to the copy sheet conveyance direction, but may be arranged in the direction crossing the copy sheet conveyance direction. In the above-described embodiment, the vicinity of the discharge port is described. However, a similar jam detecting device may be incorporated at an arbitrary position in the copy sheet conveyance path.

In addition, the present invention is limited only to the matters described in the claims, and various modifications are possible.

[0039]

According to the present invention, when a signal is output from the discharged sheet detection means, a copy sheet conveyance failure is detected based on the fact that no pulse is output from the pulse output means for a predetermined time or more. When a conveyance failure occurs in a copy sheet, it can be immediately detected. Therefore, the copy sheet may be crumpled in the copier,
Jam detection is performed before the rollers are entangled. Therefore, even if a copy sheet jam occurs, a subsequent jam countermeasure process can be easily performed.

Further, the jam of a long copy sheet can be more accurately determined.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically illustrating an internal configuration of a copying machine according to an embodiment of the present invention.

FIG. 2 is a perspective view showing an external configuration of a copying machine according to an embodiment of the present invention.

FIG. 3 is a perspective view showing an appearance of the copying machine according to the embodiment of the present invention at the time of copying.

FIG. 4 is an illustrative plan view of the vicinity of an outlet in a copying machine according to an embodiment of the present invention;

FIG. 5 is an illustrative view showing a configuration of a jam detecting device according to one embodiment of the present invention;

FIG. 6 is a timing chart for explaining a discriminating operation of the jam discriminating circuit shown in FIG. 5;

[Explanation of symbols]

 36 Discharge roller 54 Discharge port 55 Discharge detection switch 230, 231, 232 Pulse output device 233 Rotating disk 234 Light emitting / receiving element pair 235 Jam discrimination circuit

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-223049 (JP, A) JP-A-4-148755 (JP, A) JP-A-4-80158 (JP, A) JP-A-51- 15440 (JP, A) JP-A-63-300048 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B65H 7/06

Claims (2)

(57) [Claims] 1. A to feed transportable copy sheet along the conveying path, transferring the image formed by an electrophotographic system to a copy sheet being fed, the copying machine of the type for fixing the transferred image on the copy sheet near the jam a detection device, provided in the transfer route, a discharge sheet detecting means for outputting a signal when the copy sheet is present at that position, the output sheet detecting means as viewed in the conveying direction of the copying sheet for
At a predetermined interval in the direction crossing the copy sheet transport direction
They are spaced, and at least two pulse output means for outputting a pulse in accordance with the movement of the copy sheets existing in the conveyance route, and the signal is output from the output sheet detecting means, and said two pulses A jam discriminating means for discriminating that a conveyance failure of a copy sheet has occurred based on the fact that a pulse has not been output from any one or more of the output means for a predetermined time or more. Jam detection device. 2. The pulse output means is provided in three units,
At the center of the transport path, and the other two at both ends of the transport path.
2. The arrangement according to claim 1, wherein the respective arrangements are made.
Jam detection device for copiers.