JP2012030901A - Feeding device, image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a feeding device where "collision noise at rear end" caused by a collision of the rear end of a recording medium on a guide member when the rear end of the recording medium passes a stepped portion is prevented even if the stepped portions are formed in the guide member when a plurality of guide members are joined to form a feeding path of the recording medium, and to provide an image forming apparatus.SOLUTION: The feeding device includes: guide members 19A, 19B having steps in a surface opposite to the recording medium P; and a moving means 31 that moves a protrusion member 32 disposed in a downstream to a position of the steps to a position closer to the recording medium P exceeding the height of the steps. In the protrusion member 32, a protruding surface portion, a boundary surface (recess surface) and a flat surface are formed on a surface opposite to the recording medium P in a feeding direction. The moving means 31 moves the protruding member 32 to a position closer to the recording medium P immediately before the end of the recording medium P passes the stepped position.

Description

  The present invention relates to a conveyance device that conveys a recording medium and an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine including the same, and in particular, a guide member having a step in the conveyance path is installed. The present invention relates to a transport apparatus and an image forming apparatus.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, a technique is known in which a guide member (guide plate) for guiding the conveyance of a recording medium is installed in a conveyance apparatus for conveying a recording medium (for example, (See Patent Document 1).

In such an image forming apparatus, it is known that the rear end of the recording medium strongly hits the guide member or the like and an annoying impact sound (such a collision sound is referred to as “rear end splash sound”) is generated. Yes.
And in order to solve such a problem, in patent document 1, the guide member which can be rotated is installed in the position where a rear end splash sound is generated, and the rear end of the recording medium collides with the guide member. A technique for rotating the guide member before is disclosed.

In a conventional image forming apparatus, when a plurality of guide members (guide plates) are connected to form a recording medium conveyance path, a step is generated at the connecting portion, and the position of the step is determined on the recording medium. When the rear end passes, the rear end of the recording medium strongly hits the guide member, and a “rear end splashing sound” is generated.
In particular, such a problem arises when a conveyance path for conveying the recording medium while curving the recording medium is provided at a position downstream of the step in the conveyance direction for the purpose of downsizing the image forming apparatus. Is remarkable because the trailing edge of the recording medium curved by the conveyance path strikes the guide member very strongly immediately after passing the position of the step.

  The present invention has been made to solve the above-described problems. For example, when a plurality of guide members are connected to form a recording medium conveyance path, a step is formed on the guide members. However, when the rear end of the recording medium passes through the position of the step, the rear end of the recording medium strongly hits the guide member and no “rear end splashing” is generated, and the image forming apparatus. To provide an apparatus.

  According to a first aspect of the present invention, there is provided a transport device for transporting a recording medium, which guides the transport of the recording medium so as to face the recording medium, and is disposed on a surface facing the recording medium. A guide member having a step in a direction away from the recording medium, and disposed at a position downstream of the guide member in the conveyance direction of the recording medium with respect to the position of the step in the guide member. A projecting member formed so as to project in the approaching direction, a position where the projecting member approaches the recording medium beyond the height of the step, and a position away from the recording medium without exceeding the height of the step, A projecting member, wherein the projecting member has a convex surface portion formed in an R shape in a direction in which the surface facing the recording medium approaches the recording medium on the upstream side in the conveyance direction of the recording medium, A flat surface formed so as to be parallel to the opposing surface of the guide member on the downstream side in the conveyance direction of the recording medium, and a concave surface with a gentle boundary between the curved surface portion and the flat surface portion. The moving means moves the projecting member from the moving away position to the approaching position before the rear end of the recording medium passes through the stepped position.

  In addition, in the invention according to claim 1, the transfer device according to claim 2 is configured such that the moving means can change the approaching position of the protruding member.

  A transport apparatus according to a third aspect of the present invention is the transport apparatus according to the second aspect, further comprising detection means for directly or indirectly detecting the thickness or basis weight of the transported recording medium, The moving means changes the approaching position based on the detection result of the detecting means.

  The transport device according to a fourth aspect of the present invention is the transport device according to the third aspect, wherein the thickness of the recording medium is detected when the detection means detects that the thickness or basis weight of the recording medium is large. Alternatively, as compared with the case where the basis weight is detected to be small, the approaching position is variable so as to be closer to the recording medium.

  According to a fifth aspect of the present invention, there is provided a transport apparatus according to the second aspect of the present invention, wherein the transport speed of the recording medium can be varied, and the moving means is in accordance with the transport speed of the recording medium. The approaching position is variable.

  According to a sixth aspect of the present invention, there is provided the transport apparatus according to the fifth aspect, wherein the approaching position is higher when the transport speed of the recording medium is higher than when the transport speed of the recording medium is slow. It is variable so as to be closer to the recording medium.

  According to a seventh aspect of the present invention, there is provided the transport device according to any one of the first to sixth aspects, wherein the moving means has a predetermined thickness or basis weight of the transported recording medium. Only in the above case, before the rear end of the recording medium passes through the position of the step, the projecting member is moved from the position to move away to the position to approach.

  Further, according to an eighth aspect of the present invention, there is provided a transport apparatus according to any one of the first to seventh aspects, further comprising a detecting unit that detects a transport position of the transported recording medium, and the moving unit. Is based on the detection result of the detection means, and moves the projecting member from the position to move away to the position before the rear end of the recording medium passes through the level difference.

  A transport device according to a ninth aspect of the present invention is the transport device according to any one of the first to eighth aspects, wherein the guide is located at a position downstream of the guide member in the transport direction of the recording medium. A curved conveyance guide member is provided that guides conveyance of the recording medium while curving the recording medium so that the side facing the member is curved in a convex shape.

  An image forming apparatus according to a tenth aspect of the present invention includes the conveyance device according to any one of the first to ninth aspects.

  The present invention is a case where a recording medium transport path is formed by connecting a plurality of guide members, and even if a step is formed in the guide member, the position downstream of the transport direction with respect to the position of the step. The projecting member projecting from the opposing surface of the guide member is movably provided, and the shape of the opposing surface of the projecting member is optimized so that the projecting member is used as the recording medium immediately before the rear end of the recording medium passes through the position of the step. It is moved to the approaching position. Thereby, when the rear end of the recording medium passes through the position of the step, the trouble that the rear end of the recording medium abuts against the guide member and causes a “rear end splashing sound” is reduced, and An image forming apparatus can be provided.

1 is an overall configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a configuration diagram illustrating a conveyance device installed in the image forming apparatus of FIG. 1. FIG. 3 is a diagram illustrating a state in which the protruding member has moved to a position approaching a recording medium in the transport device of FIG. 2. (A) The enlarged view which shows the protrusion member in this Embodiment, (B) The enlarged view which shows the protrusion member of another form. (A) It is sectional drawing which looked at the guide member and the protrusion member from the upper part, (B) The front view which shows a guide member and the protrusion member. It is a graph which shows the relationship between the protrusion amount of a protrusion member when the basic weight of the recording medium conveyed differs, and the sound pressure level of a rear-end splash sound. It is a graph which shows the relationship between the protrusion amount of a protrusion member when the conveyance speed of a recording medium differs, and the sound pressure level of a rear-end splash sound. It is a figure which shows the conventional conveying apparatus.

Embodiment.
Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

First, the configuration and operation of the entire image forming apparatus will be described with reference to FIG.
In FIG. 1, reference numeral 1 denotes an apparatus main body of a copying machine as an image forming apparatus, 2 an original reading unit that optically reads image information of an original D, and 3 an exposure light L based on image information read by the original reading unit 2. Is exposed to the photosensitive drum 5, 4 is an image forming unit for forming a toner image (image) on the photosensitive drum 5, and 7 is a toner image formed on the photosensitive drum 5 on the recording medium P. A transfer section (image forming section) for transferring, 10 a document transport section for transporting a set document D to the document reading section 2, 12 to 14 a paper feed section for storing a recording medium P such as transfer paper, 17, Reference numeral 18 denotes a registration roller (registration roller pair) that conveys the recording medium P toward the transfer unit 7, 20 denotes a fixing device that fixes an unfixed image on the recording medium P, and 21 denotes a fixing roller installed in the fixing device 20. 22 is a pressure roller installed in the fixing device 20; It is.

With reference to FIG. 1, an operation during normal image formation in the image forming apparatus will be described.
First, the document D is conveyed from the document table in the direction of the arrow in the drawing by the conveyance roller of the document conveyance unit 10 and passes over the document reading unit 2. At this time, the document reading unit 2 optically reads the image information of the document D passing above.
Then, the optical image information read by the document reading unit 2 is converted into an electric signal and then transmitted to the exposure unit 3 (writing unit). Then, exposure light L such as laser light based on the image information of the electrical signal is emitted from the exposure unit 3 toward the photosensitive drum 5 of the image forming unit 4.

On the other hand, in the image forming unit 4, the photosensitive drum 5 is rotated in the clockwise direction in the drawing, and image information is transferred onto the photosensitive drum 5 through a predetermined image forming process (charging process, exposure process, development process). An image (toner image) corresponding to is formed.
Thereafter, the image formed on the photosensitive drum 5 is transferred onto the recording medium P conveyed by the registration rollers 17 and 18 in the transfer unit 7 as an image forming unit.

On the other hand, the recording medium P conveyed to the transfer unit 7 (image forming unit) operates as follows.
First, one of the plurality of paper feeding units 12, 13, and 14 of the image forming apparatus main body 1 is automatically or manually selected (for example, the uppermost paper feeding unit 12 is selected). To do.)
Then, the uppermost sheet of the recording medium P stored in the paper feeding unit 12 is transported toward the position of the transport path K.

  Thereafter, the recording medium P passes through a conveyance path K in which a plurality of conveyance rollers are arranged, and reaches the position of the registration rollers 17 and 18. Then, the recording medium P that has reached the positions of the registration rollers 17 and 18 is directed to the transfer unit 7 (image forming unit) at the same timing in order to align with the image formed on the photosensitive drum 5. Be transported.

After the transfer process, the recording medium P passes through the position of the transfer unit 7 and then reaches the fixing device 20 through the conveyance path. The recording medium P that has reached the fixing device 20 is fed between the fixing roller 21 and the pressure roller 22, and the image is fixed by the heat received from the fixing roller 21 and the pressure received from both members 21 and 22. The The recording medium P on which the image has been fixed is delivered from between the fixing roller 21 and the pressure roller 22 (a nip portion) and then discharged from the image forming apparatus main body 1.
Thus, a series of image forming processes is completed.
In the image forming apparatus 1 according to the present embodiment, the conveyance speed (process linear speed) of the recording medium P is set to 550 mm / s.

Next, with reference to FIGS. 2 to 5, the conveyance device 30 that is characteristic in the present embodiment will be described in detail.
With reference to FIGS. 2 and 3, the conveyance device 30 includes a recording medium P conveyance path from the position of the conveyance rollers 15 and 16 (conveying roller pair) to the position of the registration rollers 17 and 18 (registration roller pair). A first guide plate 19A, a second guide plate 19B, and a third guide plate 19C are provided along the transport path on the front surface (image forming surface) side of the recording medium P, and the back surface (non-image) of the recording medium P is provided. A counter guide plate 19D is provided on the (formation surface) side. In addition, a protruding member 32 is provided at the position of the second guide plate 19B, and a photosensor 40 (detecting means) is provided at the position of the third guide plate 19C.

The recording medium P is conveyed by the conveying device 30 toward the transfer unit 7 (the position where the photosensitive drum 5 and the transfer roller are opposed to each other) as an image forming unit that forms an image on the recording medium P. become.
Specifically, the recording medium P that has reached the position of the transport rollers 15 and 16 via the transport path K from the paper feeding unit is transported to the positions of the registration rollers 17 and 18 while being further guided by the guide plates 19A to 19D. The recording medium P transported to the position of the registration rollers 17 and 18 is subjected to skew correction (skew correction) by the leading end of the recording medium P being abutted against the registration rollers 17 and 18 whose rotation drive has been stopped, and then the photosensitive medium P. The image is conveyed toward the transfer unit 7 (image forming unit) in time with the image on the body drum 5. Thus, a desired image is transferred onto the recording medium P.

  More specifically, the registration rollers 17 and 18 are a pair of rollers disposed on the downstream side in the conveyance direction of the recording medium P with respect to the transfer unit 7 (image forming unit). The registration rollers 17 and 18 are configured to be rotationally driven and stopped independently of the conveying rollers 15 and 16 by a motor (not shown). Then, by the on / off operation of the motor, as described above, after the leading end of the recording medium P hits the registration rollers 17 and 18 in a state where the rotational driving is stopped and the skew correction / longitudinal registration correction is performed, a predetermined value is obtained. The recording medium P is conveyed toward the transfer unit 7 (image forming unit) by the registration rollers 17 and 18 that have started to rotate at the timing.

Here, the first guide plate 19 </ b> A and the second guide plate 19 </ b> B are guide members having a step in a direction away from the recording medium P on the surface facing the recording medium P.
Specifically, each of the first guide plate 19A and the second guide plate 19B is a flat plate having a thickness of 1.0 mm, and both guide plates 19A and 19B are joined together by spot welding, caulking, or the like. A substantially flat guide member is formed. In such guide members 19A and 19B, a step corresponding to the plate thickness (1.0 mm) of the guide plate 19A is formed at the joining portion of the two guide plates.

In this way, by connecting a plurality of guide plates (guide members) to form a single guide member, the cost of the guide member can be reduced. In particular, when a large guide member is formed or when a guide member having a relatively complicated shape is formed, the above-described merit is increased.
In the present embodiment, the second guide plate 19B is disposed on the side farther from the recording medium P than the first guide plate 19A, and the step between the two guide plates 19A and 19B is moved away from the recording medium P. Therefore, it is possible to suppress the problem that the leading edge of the recording medium P is caught by a step and a jam (paper jam) occurs. That is, when the step is formed in a direction approaching the recording medium P (when the second guide plate 19B is disposed closer to the recording medium P than the first guide plate 19A), the recording medium P is used. Jam (paper jam) is likely to occur due to the tip of the paper being caught in the step.

Further, the transport device 30 in the present embodiment has guide members 19A and 19B having a step at a position downstream of the guide members 19A and 19B having a step (downstream in the transport direction of the recording medium P). A curved conveyance guide member (curved conveyance path) is provided that guides conveyance while curving the recording medium P so that the side facing the convex curve is convex. In the present embodiment, a part of the counter guide plate 19D and the third guide plate 19C mainly function as a curved guide member.
By providing the curved conveyance guide members 19C and 19D, the conveyance path of the recording medium P from the paper feeding unit to the image forming unit 7 can be formed relatively short, so that the image forming apparatus 1 can be reduced in size. The

Here, the second guide plate 19B is located at a position downstream of the level difference between the first guide plate 19A and the second guide plate 19B (guide member) (on the downstream side in the conveyance direction of the recording medium P). A projecting member 32 formed so as to project from the opposing surface (conveying surface) of the (guide member) in a direction approaching the recording medium P is disposed. The protruding member 32 exceeds the height of the step before the rear end of the recording medium P passes through the step between the first guide plate 19A and the second guide plate 19B (at the immediately preceding timing). It is for moving to a position approaching P and regulating the posture of the recording medium P.
The protruding member 32 can be formed of a resin material or the like. Further, in order to reduce the sliding resistance with the recording medium P, the opposing surface of the protruding member 32 (the conveying surface facing the recording medium P to be conveyed) may be coated with a low friction material or the like. it can.

The protruding member 32 is installed at the tip of the moving mechanism 31 as a moving means, and is a position (the position shown in FIG. 2) that moves away from the recording medium P without exceeding the height of the step by the moving mechanism 31 (moving means). .) And a position approaching the recording medium P beyond the height of the step (the position in FIG. 3).
Specifically, the moving mechanism 31 (moving means) includes a holding plate 33 that holds the protruding member 32, a rack gear 34 fixed to the holding plate 33, a pinion gear 35 that meshes with the rack gear, and a stepping motor that rotationally drives the pinion gear 35. 46, etc., and is held on the side plate of the transfer device 30 so as to be movable in the direction of the double arrow in FIG. Then, when the pinion gear 35 is rotationally driven by the stepping motor 46 controlled by the control unit 45, the rack gear 34 moves in the left-right direction in FIG. 2 and FIG. The length protruding from the conveying surface of the guide plate 19B in the direction approaching the recording medium P and the length indicated by the symbol T in FIG. 3) is variable. In the first embodiment, in the state shown in FIG. 3, the protruding amount T of the protruding member 32 is set to about 1.7 mm with respect to the step t (= 1.0 mm).

  4A, the surface of the protruding member 32 that faces the recording medium P (the recording medium P that passes through the position) is upstream (upstream in the conveyance direction of the recording medium P). In the direction approaching the recording medium P, and the opposing surface of the second guide plate 19B (guide member) on the downstream side (on the downstream side in the conveyance direction of the recording medium). A flat surface portion 32c formed so as to be substantially parallel to the (conveying surface), and a boundary portion 32b (concave surface portion) connecting the curved surface portion 32a and the flat surface portion 32c is formed with a gentle concave surface. ing. That is, the opposing surface of the projecting member 32 has a convex surface portion 32a, a boundary portion 32b (concave surface portion), and a flat surface portion 32c that are continuously and smoothly formed as one waveform along the conveyance direction of the recording medium. Yes.

In the transport device 30 configured as described above, before the trailing end of the recording medium P passes through the position of the step between the first guide plate 19A and the second guide plate 19B (at the timing immediately before). The moving mechanism 31 is controlled so that the protruding member 32 is moved from the position shown in FIG. 2 (position away from the recording medium P) to the position shown in FIG. 3 (position approaching the recording medium P).
Specifically, when the front end (conveying position) of the recording medium P is detected by the photosensor 40 as the detecting means, the information is sent to the control unit 45, and from the length of the recording medium P in the conveying direction, The time for the trailing edge of the recording medium P to pass through the level difference is calculated. Then, the stepping motor 46 is operated a predetermined time earlier than the calculated time (the time when the trailing edge of the recording medium P passes through the step position, which is calculated in advance and converted into data). As a result, the protruding member 32 is moved to the position shown in FIG.

Hereinafter, the operation of the protruding member 32 (moving mechanism 31) in the transport device 30 configured as described above will be described in detail.
First, as shown in FIG. 2, when the leading end of the recording medium P passes through the position of the projecting member 32, the projecting amount T of the projecting member 32 is the level difference between the first guide plate 19A and the second guide plate 19B (first The guide plate 19A is retracted to a position not exceeding (the thickness of the guide plate 19A is 1.0 mm) (the projection amount T is substantially 0 mm). As a result, it is possible to suppress a problem in which the leading edge of the recording medium P comes into contact with the protruding member 32 to cause a jam (paper jam). Further, even if the leading end of the recording medium P comes into contact with the protruding member 32, the contact position is the curved surface portion 32a, so that the leading end of the recording medium P is guided along the shape. The tip of P is not caught by the protruding member 32.
Thereafter, when the front end of the recording medium P is optically detected by the photosensor 40, the detection information is sent to the control unit 45. The stepping motor 46 is controlled by the controller 45 immediately before the rear end of the recording medium P passes through the step between the first guide plate 19A and the second guide plate 19B, and the rack gear 34 is driven by the rotation of the pinion gear 35. At the same time, the protruding member 32 is slid to the position shown in FIG. 3 (the position where the protruding amount T of the protruding member 32 is larger than the step t).

Thus, when the rear end of the recording medium P passes through the step between the first guide plate 19A and the second guide plate 19B, the curved shape of the recording medium P becomes relatively gentle as shown in FIG. Thus, since the energy that moves toward the second guide plate 19B when the rear end of the recording medium P passes through the step is reduced, recording is performed when the rear end of the recording medium P passes through the position of the step. The trouble that the rear end of the medium P abuts against the second guide plate 19B and causes a “rear end splashing sound” is reduced.
Specifically, when the inventor of the present application conducted an experiment, the recording medium P in the conventional transport device 130 (the projecting member 32 is not installed at the position of the second guide plate 119B) shown in FIG. The sound pressure level of the “rear end splashing sound” generated when the rear end passes through the step between the first guide plate 19A and the second guide plate 119B (the portion surrounded by the broken line in FIG. 8) (see FIG. 8 (measured by the microphone 140 installed at a position 30 mm away from the opposing guide plate 19D) was about 91 dB (decibel). As shown in FIG. 8, in the conventional transport device 130, the recording medium P is greatly curved when the rear end of the recording medium P passes through the step, and the energy moves toward the second guide plate 119B. Therefore, when the rear end of the recording medium P passes through the position of the step, the rear end of the recording medium P strongly hits the second guide plate 119B, and a large “rear end splashing sound” is generated.
On the other hand, in the transport apparatus 30 according to the present embodiment, the sound pressure level of the “rear end splash” measured by the microphone 140 installed at the same position is about 80 dB (decibel), and is described above. It was confirmed that there was a silencing effect of about 11 dB (decibel) than the conventional one.

Here, after the state of FIG. 3, the rear end of the recording medium P passes through the position of the protruding member 32. At this time, the rear end of the recording medium P is the opposite surface (convex surface portion 32 a, The boundary portion 32b and the plane portion 32c are smoothly and continuously formed like a single waveform, and are gently guided along the conveyance surface. Does not occur.
In addition, instead of the protruding member 32 (shown in FIG. 4 (A)) in the present embodiment, the inventor of the present application has only a convex surface portion with an R-shaped facing surface as shown in FIG. 4 (B). The projecting member 320 formed in the above is installed in the conveying device 30 and the above-described “rear edge splashing” is measured. As a result, the “rear end is generated when the rear end of the recording medium P passes through the step. The sound pressure level of “Netone” was about 80 dB (decibel) as in the present embodiment, but after that, the rear end of the recording medium P passes the position surrounded by the broken line in FIG. A collision sound of about 78 dB (decibel) was confirmed at the timing. In order to prevent the occurrence of such secondary collision noise (rear edge splashing), the shape of the opposing surface (conveying surface) of the protruding member 32 should be optimized as in the present embodiment. Is important.

Here, as shown in FIG. 5, in the present embodiment, one protruding member is formed across the width direction (the left-right direction in FIG. 5 and the direction perpendicular to the plane of FIG. 2 and FIG. 3). Instead, a plurality of projecting members 32 (in this embodiment, five projecting members 32) are formed in the width direction. Specifically, a plurality of protruding members 32 are arranged in parallel in the width direction on the holding plate 33 of the moving mechanism 31 with a space between each other.
Further, the second guide plate 19B (guide member) moves the plurality of protruding members 32 to the positions corresponding to the plurality of protruding members 32 (the movement in the vertical direction in FIG. 5A). A plurality of openings are formed to enable this.
Thus, by forming the plurality of projecting members 32 in the width direction, the opening of the second guide plate 19B is also formed in the width direction, so that the leading edge of the recording medium P is the first. 2 When passing through the position of the opening of the guide member 19B (in the state shown in FIG. 2), the tip of the recording medium P (the corners at both ends in the width direction at the tip) is the opening of the second guide member 19B. The trouble that jams (paper jam) by the hook and the trouble that the transportability deteriorates is suppressed. That is, when one projecting member 32 is formed across the width direction, one opening of the second guide plate 19B is also formed across the width direction, so that the leading end of the recording medium P is the second guide member 19B. When passing through the position of the opening, the leading edge of the recording medium P (the corners at both ends in the width direction at the leading edge) is caught by the opening of the second guide member 19B, causing jamming (paper jam) and transportability. The possibility that it falls will become high.
In order to ensure such an effect, the plurality of openings (the plurality of protruding members 32) formed in the second guide plate 19B have widths in various sizes of recording media P that can be conveyed by the apparatus main body 1. It is preferable that the layout is made so as not to overlap any of the corners at both ends in the direction.

Further, in the transport device 30 in the present embodiment, the moving mechanism 31 (moving means) is configured to be able to vary the protruding amount T (position approaching the recording medium P to be transported) in the protruding member 32.
Specifically, referring to FIG. 2, a paper thickness sensor 47 is installed in the transport path of the apparatus main body 1 as detection means for detecting the thickness of the recording medium P to be transported (paper passing). The paper thickness sensor 47 is installed in the conveyance path of the recording medium P from the paper feeding section including the paper feeding section to the position of the protruding member 32, and directly and optically determines the paper thickness of the recording medium P. It is to detect.
The moving mechanism 31 (moving means) is configured to be able to vary the protruding amount T (position approaching the recording medium P to be conveyed) on the protruding member 32 based on the detection result of the paper thickness sensor 47 (detecting means). Has been. Specifically, when the thickness of the recording medium P is detected by the paper thickness sensor 47, the protruding amount T of the protruding member 32 is larger than when the thickness of the recording medium P is detected to be small. It is variably controlled so that it becomes larger (the position approaching the recording medium P being conveyed becomes the position approaching the recording medium P).

  In the present embodiment, the above-described variable control is performed based on the paper thickness (thickness) of the recording medium P that is directly detected by the paper thickness sensor 47. The above-described variable control can be performed based on the basis weight of the recording medium P detected at the same time, or the above-described variable control is performed based on the thickness or basis weight of the recording medium P detected indirectly by the detection means. You can also do it. This is because there is a correlation between the thickness of the recording medium P and the basis weight. Further, as a detecting means for indirectly detecting the thickness or basis weight of the recording medium P, based on information about the recording medium P input by the user to the operation panel (not shown) of the apparatus main body 1 or the like. What is detected indirectly can also be used.

By performing such variable control, it is possible to reliably and efficiently reduce the occurrence of “rear edge splashing” for various recording media P having different thicknesses and basis weights.
FIG. 6 shows the protruding amount T of the protruding member 32 (the protruding amount T in the state of FIG. 3) and the sound pressure level of the trailing edge splash sound when the basis weight of the recording medium P being conveyed is different. It is a graph which shows the relationship between the measurement method and the measurement method described in FIG. In FIG. 6, a graph S1 shows an experiment result when the recording medium P having a basis weight of 360 g / m ² is passed through, and a graph S2 shows an experiment when the recording medium P having a basis weight of 208 g / m ² is passed through. The graph S3 is an experimental result when the recording medium P having a basis weight of 128 g / m ² is passed. From the experimental results shown in FIG. 6, it can be seen that the larger the basis weight (or thickness) of the recording medium P, the worse the degree of “rear edge splashing”. This is because as the basis weight (or thickness) of the recording medium P increases, the rigidity of the recording medium P increases, and immediately after the rear end of the recording medium P passes through the step, it is directed toward the second guide plate 19B. This is because the energy to move increases. From the experimental results shown in FIG. 6, the degree of “rear end splashing” can be reduced by setting the protruding amount T of the protruding member 32 to be larger than the step t (1.0 mm). It can be seen that the silencing effect when the protrusion amount T is increased is increased as the basis weight (or thickness) of is increased. This is because when the basis weight (or thickness) of the recording medium P is changed, the rigidity of the recording medium P is also changed, so that an appropriate protrusion amount T for smoothing the curved shape of the recording medium P is changed. Conceivable.
In the present embodiment, the protruding amount T of the protruding member 32 is varied according to the thickness (basis weight) of the recording medium P detected by the paper thickness sensor 47 based on such experimental results. Therefore, the occurrence of “rear edge splashing” can be reliably and efficiently reduced for various recording media P having different thicknesses and basis weights.

In the present embodiment, the moving mechanism 31 is used when the protrusion amount T is variably controlled in accordance with the thickness (basis weight) of the recording medium P detected by the paper thickness sensor 47 (detection means). The (moving means) moves the protruding member 32 of FIG. 3 immediately before the rear end of the recording medium P passes through the level difference only when the thickness (basis weight) of the recording medium P being conveyed is equal to or greater than a predetermined value. Control to move to a position can be performed.
Specifically, only when the thickness of the recording medium P detected by the paper thickness sensor 47 (detecting means) corresponds to a basis weight of 208 g / m ² or more, the trailing edge of the recording medium P is the position of the step. The protruding member 32 is moved to the position shown in FIG. On the other hand, when the thickness of the recording medium P detected by the paper thickness sensor 47 (detection means) corresponds to a basis weight of less than 208 g / m ² (this is a case where thin paper is passed). In other words, the projecting member 32 is kept retracted to the position shown in FIG. 2 even before the rear end of the recording medium P passes through the level difference (the projecting member 32 is not moved).
From the experimental result of FIG. 6, when the recording medium P having a small thickness (basis weight) is passed, the rigidity of the recording medium P is low and the rear end of the recording medium P passes through the step. This is because the energy that moves immediately toward the second guide plate 19 </ b> B is small, and thus the “rear end splash sound” that is generated is small. Therefore, in such a case, energy saving of the apparatus main body 1 and mechanical extension of the moving mechanism 31 can be achieved without performing movement control of the protruding member 32.

In the present embodiment, the protrusion amount T of the protrusion member 32 is variably controlled based on the paper thickness and basis weight of the recording medium P detected by the paper thickness sensor 47 (detection means). In the image forming apparatus in which the conveyance speed (process linear speed) of the recording medium P is variable, the protrusion amount T (position approaching the recording medium P to be conveyed) in the protruding member 32 according to the conveyance speed (process linear speed) of the recording medium P. ) Can be varied. Specifically, when the conveyance speed of the recording medium P is high, the protruding amount T of the protruding member 32 is larger (closer to the recording medium P being conveyed) than when the conveyance speed of the recording medium P is low. The position can be variably controlled so that the position is closer to the recording medium P).
This is because as the conveyance speed of the recording medium P increases, the energy that moves toward the second guide plate 19B immediately after the rear end of the recording medium P passes through the step increases. This is because the degree of "is increased.
FIG. 7 shows the protruding amount T of the protruding member 32 (the protruding amount T in the state of FIG. 3) and the sound pressure level of the trailing edge splash sound when the conveying speed of the recording medium P being conveyed is different. It is a graph which shows the relationship between the measurement method and the measurement method described in FIG. In FIG. 7, a graph Q1 is an experimental result when the conveyance speed of the recording medium P is 550 mm / s, and a graph Q2 is an experimental result when the conveyance speed of the recording medium P is 250 mm / s. From the experimental results shown in FIG. 7, it can be seen that as the conveyance speed of the recording medium P increases, the degree of “rear edge splashing” deteriorates as a whole. Then, as the conveyance speed of the recording medium P increases, the protrusion amount T of the protruding member 32 is set to be larger, so that “the trailing edge splash sound” generated when the conveyance speed of the recording medium P is low is equivalent to “ “Rear edge splashing” can be reduced.
In a predetermined image forming apparatus, when the conveyance speed (process linear speed) of the recording medium P is variable, in addition to the “normal mode” in which the recording medium P is fed at a normal conveyance speed, the fixing device 20 In the fixing process performed in step 1, the “low speed mode” in which the recording medium P is fed at a transport speed slower than the normal transport speed may be selected in order to ensure the fixability of the fixed image. Then, the conveyance speed of the recording medium P is detected indirectly based on the information about the “normal mode” and the “low speed mode” input to the operation panel (not shown) of the apparatus main body 1 by the user. Alternatively, it may be performed directly from a change in the input current of the drive motor 48 (a variable speed drive motor that rotationally drives the transport rollers 15 and 16) shown in FIG.

  As described above, in the present embodiment, a plurality of guide plates 19A and 19B (guide members) are connected to form a conveyance path for the recording medium P, and there are steps in the guide members 19A and 19B. Even if formed, the projecting member 32 projecting from the facing surface of the second guide plate 19B (guide member) is movably provided at a position on the downstream side in the transport direction with respect to the position of the step, and is opposed to the projecting member 32. The shape of the surface is optimized, and the protruding member 32 is moved to a position approaching the recording medium P immediately before the rear end of the recording medium P passes the position of the step. As a result, when the rear end of the recording medium P passes through the position of the step, the rear end of the recording medium P abuts against the second guide plate 19B, thereby reducing the problem that the “rear end splashing sound” is generated. it can.

In the present embodiment, the present invention is applied to the conveyance device 30 installed in the monochrome image forming apparatus 1. However, the present invention is naturally applied to the conveyance device installed in the color image forming apparatus. Can be applied.
Further, in the present embodiment, the present invention is applied to the conveyance device 30 installed in the electrophotographic image forming apparatus 1, but the application of the present invention is not limited to this, and other methods can be used. As long as it is a conveyance device installed in an image forming apparatus (for example, an inkjet image forming apparatus) and a conveyance device in which a guide member having a step is installed, all of those conveyance devices are used. Of course, the present invention can be applied.
Even in those cases, the same effects as in the present embodiment can be obtained.

Further, in the present embodiment, the present invention is applied to the transport device 30 disposed at a position upstream of the registration rollers 17 and 18 in the transport direction, but the application of the present invention is limited to this. Of course, the present invention is naturally applied to all of the transfer devices as long as the transfer device is installed at other positions as long as the guide member having a step is installed. Can do.
In the present embodiment, the present invention is applied to the conveyance device 30 in which the curved conveyance guide members 19C and 19D (curved conveyance path) are formed on the downstream side in the conveyance direction of the guide members 19A and 19B having steps. Even when the curved conveying guide member (curved conveying path) is not formed on the downstream side in the conveying direction of the guide members 19A and 19B having a step, the recording member is used when the trailing end of the recording medium passes through the step. Of course, the present invention can also be applied to all the transporting devices as long as the rear end of the transporting device collides with the guide member.
Further, in the present embodiment, the present invention is applied to the conveyance device 30 in which the guide members 19A and 19B having steps are linear conveyance paths, but the guide members having steps are curved conveyance paths. Even if the conveyance path is a (curved conveyance path), all of them can be used as long as the rear end of the recording medium collides with the guide member when the rear end of the recording medium passes through the step. Of course, the present invention can also be applied to other transport apparatuses.
Even in those cases, the same effects as in the present embodiment can be obtained.

In the present embodiment, the rear end of the recording medium P obtained in advance is triggered by the timing at which the front end of the recording medium P is optically detected by the photosensor 40 disposed in the vicinity of the registration rollers 17 and 18. The projecting member 32 is moved to a position approaching the recording medium P at a timing immediately before passing through the position of the step.
On the other hand, a photo sensor for detecting the recording medium P is disposed on the upstream side of the projecting member 32 (on the upstream side in the conveyance direction of the recording medium P), and the front end of the recording medium P is optically detected. After the elapse of a predetermined time (the time calculated from the transport distance from the position of the photo sensor to the position of the protruding member 32 and the transport speed of the recording medium P + α), the protruding member 32 is recorded. It can also be moved to a position approaching the medium P.
Further, a photo sensor for detecting the recording medium P is arranged at the position of the paper feeding unit, and a predetermined time (from the position of the paper feeding unit to the position of the brake plate 31) after the paper feeding operation in the paper feeding unit is started. It is also possible to move the protruding member 32 to a position approaching the recording medium P after a lapse of time + α calculated from the transport distance to reach and the conveyance speed of the recording medium P).
In these cases, the same effect as in the present embodiment can be obtained.

  It should be noted that the present invention is not limited to the present embodiment, and it is obvious that the present embodiment can be modified as appropriate within the scope of the technical idea of the present invention, other than suggested in the present embodiment. is there. In addition, the number, position, shape, and the like of the constituent members are not limited to the present embodiment, and the number, position, shape, and the like suitable for implementing the present invention can be achieved.

1 image forming apparatus body (apparatus body),
15, 16 transport rollers,
17, 18 Registration roller,
19A 1st guide plate (guide member),
19B 2nd guide plate (guide member),
19C 3rd guide plate (curved conveyance guide member),
19D opposing guide plate (curved conveyance guide member),
30 transport device,
31 moving mechanism (moving means),
32 protruding member,
32a convex part, 32b boundary part (concave part), 32c plane part,
33 holding plate, 34 rack gear, 35 pinion gear,
40 Photosensor (detection means),
47 Paper thickness sensor (detection means), P recording medium.

JP 2007-276951 A

Claims (10)

A transport device for transporting a recording medium,
A guide member having a step in a direction away from the recording medium on a surface facing the recording medium while guiding the conveyance of the recording medium facing the recording medium;
A projecting member disposed at a position downstream of the position of the step in the guide member in the conveyance direction of the recording medium and formed so as to project in a direction approaching the recording medium from an opposing surface of the guide member; ,
Moving means for moving the protruding member between a position approaching the recording medium beyond the height of the step and a position moving away from the recording medium without exceeding the height of the step;
With
The projecting member has a convex surface portion formed in an R shape in a direction in which the surface facing the recording medium approaches the recording medium on the upstream side in the recording medium conveyance direction, and the guide member on the downstream side in the conveyance direction of the recording medium. A plane portion formed so as to be parallel to the surface, and a boundary portion connecting the curved surface portion and the plane portion is formed with a gentle concave surface,
The transfer device moves the protruding member from the moving away position to the approaching position before the rear end of the recording medium passes through the position of the step.   The transport apparatus according to claim 1, wherein the moving unit is configured to be able to change the approaching position of the protruding member. Comprising detection means for directly or indirectly detecting the thickness or basis weight of the recording medium being conveyed,
The transport apparatus according to claim 2, wherein the moving unit varies the approaching position based on a detection result of the detection unit.   When the thickness or basis weight of the recording medium is detected by the detection means, the approaching position is closer to the recording medium than when the thickness or basis weight of the recording medium is detected to be small. The conveying apparatus according to claim 3, wherein the conveying apparatus is variable so as to become. It is configured so that the conveyance speed of the recording medium can be varied,
The transport apparatus according to claim 2, wherein the moving unit varies the approaching position according to a transport speed of the recording medium.   6. The transport apparatus according to claim 5, wherein when the recording medium transport speed is high, the approaching position is variable so as to be closer to the recording medium than when the recording medium transport speed is slow. .   The moving means approaches the projecting member from the position where the protruding member moves away before the rear end of the recording medium passes through the position of the step only when the thickness or basis weight of the recording medium being conveyed is equal to or greater than a predetermined value. The transport device according to claim 1, wherein the transport device is moved to a position. Comprising a detecting means for detecting a transport position of the transported recording medium,
The moving means moves the projecting member from the away position to the approached position before the rear end of the recording medium passes through the stepped position based on the detection result of the detecting means. The conveyance apparatus in any one of Claims 1-7.   A curved conveyance guide member that guides the conveyance of the recording medium while curving the recording medium at a position downstream of the guide member in the conveyance direction of the recording medium so that the side facing the guide member is curved in a convex shape. The transport apparatus according to any one of claims 1 to 8, wherein the transport apparatus is provided.   An image forming apparatus comprising the transport device according to claim 1.

Images