Recording medium feed device

Abstract

A recording medium feed device includes: a recording medium feed tray installable to and removable from a main body of the recording medium feed device; a send-out member to send out a recording medium loaded in the recording medium feed tray, the send-out member being in contact with a top face of the recording medium while applying pressure thereto at a time of installing the recording medium feed tray; and a withdrawing mechanism to withdraw the send-out member from the top face of the recording medium in the recording medium feed tray at a time of removing the recording medium feed tray.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a recording medium feed device which is installed in an image forming apparatus such as a copying machine, a printer or a printing press, a paper post-processing apparatus, and the like.

2. Description of the Related Art

As a recording medium feed device used in an image forming apparatus or the like, a device as shown in FIG. 7 has been known (for example, see JP-Tokukaihei-7-144771A).

In FIG. 7, reference numeral 101 denotes a recording medium feed roller, reference numeral 102 denotes a separating roller to be in contact with the recording medium feed roller 101 and connected to a torque limiter (not shown), and reference numeral 103 denotes a send-out roller swingably supported on the rotary shaft of the recording medium feed roller 101.

Reference numeral 104 denotes a pick-up cam which brings the send-out roller 103 into contact with paper. P loaded to be accommodated in a recording medium feed tray 106, and separates the send-out roller 103 from paper P.

Sheets of paper P sent out by the send-out roller 103 are separated into one sheet by the recording medium feed roller 101 and the separating roller 102, and conveyed to the downstream side.

Additionally, as a different mode, there has been known a recording medium feed device in which a recording medium feed tray and a recording medium feed roller are integral with a recording medium feed unit including a send-out roller and the like, and the send-out roller is always in contact with paper at the time of installing the recording medium feed tray.

However, the device described in JP-Tokukaihei-7-144771A has involved a later-described problem, that is, a so-called “no feed” in which no sheet of paper is sent out.

Recently, paper used for image forming or the like has been varied, and image forming has been performed on paper on one side of which an image is formed, that is, so-called backside paper.

The backside paper is sometimes wavy due to different degrees of shrinkage between the front and back sides of the paper. Therefore, gaps are formed between sheets when the wavy paper is loaded in the recording medium feed tray.

Hence, when the wavy sheets of paper are sent out while the send-out roller is in contact with and separated from the paper, gaps (air) between the sheets remain since the contacting time therewith is short. Thus, sufficient frictional force cannot be obtained between the send-out roller and the paper on the top, thereby causing “no feed.”

Meanwhile, regarding the above-described recording medium feed tray and the recording medium feed unit which are integral with each other, the send-out roller is always in contact with the paper. Therefore, even though “no feed” can be prevented, the same number of the recording medium feed units as that of the recording medium feed trays are required. Thus, cost is increased as the number of the recording medium feed trays is increased.

SUMMARY OF THE INVENTION

The present invention is made in view of the above problems, and an object thereof is to provide a recording medium feed device which includes an installable and removable recording medium feed tray, has a simple structure that suppresses a cost increase, and prevents “no feed.”

As described above, the inventors of the present invention have found out during their study on a recording medium feed device that, in a structure where the send-out roller is always in contact with the recording media, “no feed” can be prevented even when a wavy recording medium such as backside paper is used, since the send-out roller is always in contact with the recording media and thus no gap is formed between the recording media. However, in a structure where the recording medium feed tray and the recording medium feed unit are integral with each other, cost is increased even though it is easy to allow the send-out roller to be always in contact with the paper.

The present invention has been achieved on the idea that cost can be suppressed and “no feed” can be prevented by separating the recording medium feed tray and the recording medium feed unit, and bringing the send-out roller into contact with the top face of the recording media at the time of installing the recording medium feed tray, while withdrawing the send-out roller from the top face of the recording media at the time of removing the recording medium feed tray in order not to displace the recording media loaded in the recording medium feed tray.

The object of the present invention can be achieved by the following.

A recording medium feed device comprises: a recording medium feed tray installable to and removable from a main body of the recording medium feed device; a send-out member to send out a recording medium loaded in the recording medium feed tray, the send-out member being in contact with a top face of the recording medium while applying pressure thereto at a time of installing the recording medium feed tray; and a withdrawing mechanism to withdraw the send-out member from the top face of the recording medium in the recording medium feed tray at a time of removing the recording medium feed tray.

Thus, the send-out member is always in contact with the recording medium during installation of the recording medium feed tray. Accordingly, even when a wavy recording medium having different degrees of shrinkage between the front and back sides thereof is fed, “no feed” can be prevented.

Moreover, by withdrawing the send-out member from the top face of the recording medium in the recording medium feed tray at the time of removing the recording medium feed tray, it is possible to prevent the recording medium from being displaced. Thus, the recording medium can be prevented from being torn or defectively conveyed.

A recording medium feed device comprises: a recording medium feed tray installable to and removable from a main body of the recording medium feed device; a send-out roller to send out a recording medium loaded in the recording medium feed tray, the send-out roller being in contact with a top face of the recording medium while applying pressure thereto at a time of installing the recording medium feed tray; a roller supporting member to rotatably support the send-out roller; and a withdrawing member provided on the recording medium feed tray, to rotate the roller supporting member in a direction of withdrawing the send-out roller from the top face of the recording medium in the recording medium feed tray in accordance with an operation of removing the recording medium feed tray.

Thus, the send-out roller is always in contact with the recording medium during installation of the recording medium feed tray. Accordingly, even when a wavy recording medium having different degrees of shrinkage between the front and back sides thereof is fed, “no feed” can be prevented.

Moreover, by withdrawing the send-out roller from the top face of the recording medium in the recording medium feed tray at the time of removing the recording medium feed tray, it is possible to prevent the recording medium from being displaced. Thus, the recording medium can be prevented from being torn or defectively conveyed.

A recording medium feed device comprises: a recording medium feed tray installable to and removable from a main body of the recording medium feed device; a send-out roller to send out a recording medium loaded in the recording medium feed tray, the send-out roller being in contact with a top face of the recording medium while applying pressure at a time of installing the recording medium feed tray; and a recording medium holding member formed integrally with the send-out roller, to be in contact with the top face of the recording medium in the recording medium feed tray only at a time of removing the recording medium feed tray.

By providing the recording medium holding member to be in contact with the top face of the recording medium in the recording medium feed tray only at a time of removing the recording medium feed tray, the recording medium holding member being formed integrally with the send-out roller, the send-out roller is prevented from contacting with the recording medium. Accordingly, it is possible to prevent the recording medium loaded in the recording medium feed tray from being displaced.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not intended as a definition of the limits of the present invention, and wherein;

FIG. 1 is a schematic view showing a structure of an image forming apparatus;

FIG. 2 is a plan view of a recording medium feed tray 40A installed in a predetermined position;

FIG. 3 is a front view of the vicinity of a recording medium feed unit 400A as viewed in the direction of the arrow A in FIG. 2;

FIG. 4 is a sectional view of the recording medium feed unit 400A taken along the line B-B in FIG. 3;

FIG. 5 is a side view of the recording medium feed tray 40A as viewed in the direction of the arrow C in FIG. 2;

FIG. 6 is a view showing a state where a roller supporting member 404 is in contact with the top face of recording media in the recording medium feed tray 40A; and

FIG. 7 is a sectional view of main part of a recording medium feed device according to earlier development.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Hereinbelow, an embodiment of the present invention will be described. Note that the definitive descriptions given hereinbelow only show a best mode of the invention, and thus should not be taken as limiting in any way the definitions of the terms of the invention or the technical scope of the invention.

First, with reference to FIG. 1, a description will be given of an embodiment of an image forming apparatus having a recording medium feed device according to the present invention.

FIG. 1 is a schematic view showing a structure of an image forming apparatus as a digital copying machine.

The image forming apparatus according to this embodiment forms a toner image on a recording medium by using an electrophotographic method. The image forming apparatus includes: an automatic original feed device 1; an image reading device 2; an image forming section 3; a recording medium feed section 4; a reversed recording medium discharging and re-feeding section 5; and a reversed recording medium conveying section 6.

The automatic original feed device 1 includes: an original placing table 11 on which an original or originals are placed; an original separating unit 12 to separate originals placed on the original placing table 11 one by one; an original conveyor unit 13 including a plurality of rollers to convey an original separated by the original separating unit 12; an original discharging unit 14 to discharge the original conveyed by the original conveyor unit 13; an original discharge table 15 on which the original discharged by the original discharging unit 14 is placed; and an original reversing unit 16 including a pair of rollers to reverse an original in a double-sided copying mode.

A plurality of originals (not shown) placed on the original placing table 11 are separated by the original separating unit 12 one by one, and then the separated original is conveyed to an image reading position by the original conveyor unit 13.

The image reading position is placed under the original conveyor unit 13, and the image of the original is read through a slit 21 of the image reading device 2.

The automatic original feed device 1 is of a flap type. Thus, copying can be performed by: lifting the automatic original feed device 1 to expose a platen glass 22; and placing an original directly on the platen glass 22.

The image reading device 2 is a device to read the image of an original and obtain the image data. The image reading device 2 includes: an optical system 25 to read an image of an original; and a CCD 26 to perform photoelectric conversion on the read image.

An analog signal obtained after the photoelectric conversion is subjected to A/D conversion after analog processing. Subsequently, the signal is subjected to image processing as appropriate, and stored as image data in a memory inside a control unit (not shown).

The image forming section 3 includes: a photosensitive drum 31 having a photoconductive photosensitive layer as an image bearing member on the surface thereof; a charging unit 32 which includes a charging electrode to evenly charge the surface of the photosensitive drum 31; a laser writing unit 33 which is an exposure unit to expose the photosensitive drum 31 to light and form an electrostatic charge latent image on the photosensitive drum 31; a developing device 34 to perform reversal development of the electrostatic charge latent image formed on the photosensitive drum 31, thereby forming a toner image; a transferring unit 35 to transfer the toner image on a recording medium such as plain paper, the transferring unit 35 including a transfer electrode; a separating unit 36 to perform, from the back side of the recording medium on which the toner image has been transferred, corona discharge by using, for example, an AC voltage or an AC-DC superimposed voltage, thereby facilitating separation of the recording medium from the photosensitive drum 31; and a cleaning unit 37 to clean the photosensitive drum 31 after the transfer process has been completed.

The developer accommodated in the developing device 34 is a two-component developer whose main components are: a so-called coating carrier which is made by coating particulate ferrite with styrene-acryl resin and/or silicon resin; and, for example, an insulating, non-magnetic polymerized toner manufactured by a polymerizing method.

Reference numeral 38 denotes a conveyor belt to convey a separated recording medium, reference numeral 9 denotes a fixing device to fix the toner transferred to the conveyed recording medium, and reference numeral 63 denotes discharging rollers.

In this image forming apparatus, image forming is achieved in the following manner. The photosensitive drum 31 is rotated by an appropriate driving unit in the direction shown by the arrow, and sequentially charged by the charging unit 32. Then, an electrostatic charge latent image corresponding to the image of the original is formed by dot exposure by using the laser writing unit 33, and the electrostatic charge latent image is made into a toner image by using the developing device 34. Thereafter, through an operation of the transferring unit 35, the toner image is transferred onto a recording medium supplied by registration rollers 56 which have started to rotate.

In the recording medium feed section 4, provided are: recording medium feed trays 40A, 40B and 40C; recording medium feed units 400A, 400B and 400C of the recording medium feed trays 40A, 40B and 40C, respectively; and three recording medium feed devices 4A, 4B and 4C each including a recording medium feed device mount (not shown) to guide the recording medium feed tray and hold the recording medium feed unit, and the like. In any one of the recording medium feed devices, recording mediums P are separated into one to be fed therefrom, and conveyed toward the registration rollers 56 through a plurality of conveyor rollers provided at the downstream side. Then, the provided recording medium P is conveyed for the transfer process.

The recording medium feed devices 4A, 4B and 4C will be detailed later.

The recording medium P on which transfer has been performed is separated from the photosensitive drum 31 through an operation of the separating unit 36. The recording medium P is then subjected to a heating and compressing operation of the fixing device 9, and discharged to the outside of the machine by the discharging rollers 63.

Meanwhile, the photosensitive drum 31 that has passed through the transfer region continues to rotate, and the residual toner thereon is removed by the cleaning unit 37. Thus, the photosensitive drum 31 is ready for the next image forming.

The reversed recording medium discharging and re-feeding section 5 and the reversed recording medium conveying section 6 have a reversely conveying function to reverse and discharge the recording medium (hereinafter, referred to as paper) P, thereby allowing image forming onto the back side of the paper.

Next, an embodiment of the recording medium feed device according to the present invention will be described with reference to the drawings.

Since the basic structures of the three recording medium feed devices are the same, a description will be given of the recording medium feed device 4A with reference to FIGS. 2, 3, and 4.

FIG. 2 is a plan view showing the recording medium feed tray 40A which is installable and removable to and from the recording medium feed device 4A is installed in a predetermined position. FIG. 3 is a front view of the vicinity of the recording medium feed unit 400A as viewed in the direction of the arrow A in FIG. 2. FIG. 4 is a sectional view of the recording medium feed unit 400A taken along the line B-B in FIG. 3.

The recording medium feed unit 400A is provided on the main body side of the recording medium feed device. The recording medium feed unit 400A includes: a send-out roller 401 as an example of a send-out member; a recording medium feed roller 402 as an example of a recording medium feed member; a separating roller 403 as an example of a separating member; and the like.

Here, each of the rollers 401, 402 and 403 may be formed by using a belt.

Reference numeral 404 denotes a roller supporting member. The roller supporting member 404 integrally includes: a left side plate 405; a right side plate 406; and a top plate 404A connecting the left and right side plates. The roller supporting member 404 rotatably supports a send-out roller shaft 401A fixed to the send-out roller 401.

The left side plate 405 is held by a rotary shaft of the recording medium feed roller (recording medium feed roller shaft) 407 via a one-way clutch 408. The recording medium feed roller shaft 407 is connected to the one-way clutch 408 when the recording medium feed roller shaft 407 is rotated in a direction opposite to the direction in which the paper P is sent out (direction shown by the arrow W in FIG. 3). The right side plate 406 is held by the recording medium feed roller shaft 407 via a shaft bearing 409.

As shown in FIG. 3, the left side plate 405 and the right side plate 406 integrally includes a substantially triangular recording medium holding members at the left of the send-out roller 401.

The recording medium holding members are designed such that tip portions 405A and 406A thereof are in contact with the top face of a stack of paper in the recording medium feed tray 40A only at the time of removing the recording medium feed tray 40A. Thus, the send-out roller 401 is prevented from contacting with the top face of the stack of paper. The detailed description thereof will be given later.

It is preferable that the tip portions 405A and 406A are coated with a material of a low friction coefficient such as Teflon (Registered Trademark) or fluorine, or made of a low friction resin material such as polyacetal.

The recording medium feed roller shaft 407 is rotatably supported by support plates 415 and 416 formed in the recording medium feed device mount, and connected to a recording medium feed motor (not shown) via a one-turn clutch 411 which rotates in synchronization with rotation of the registration rollers 56 (see FIG. 1).

The recording medium feed roller 402 is held by the recording medium feed roller shaft 407 via a one-way clutch 410. The recording medium feed roller shaft 407 is connected to the one-way clutch 410 when the recording medium feed roller shaft 407 is rotated in a direction of sending out the paper P (direction shown by the arrow W in FIG. 3).

Through an idle gear 413, a gear 412 fixed to the recording medium feed roller shaft 407 is meshed with a gear 414 fixed to the send-out roller shaft 401A.

In FIG. 3, reference numeral 421 denotes a separating roller supporting member shaped like “C.” The separating roller supporting member 421 holds the separating roller 403 via a torque limiter 420, and is rotatably supported around a supporting shaft 422 formed in the recording medium feed device mount.

Reference numeral 423 denotes a pull spring. The pull spring 423 biases the separating roller 403 clockwise in FIG. 3, thereby causing the separating roller 403 to be in contact with the recording medium feed roller 402 while applying pressure thereto.

In a state where the separating roller 403 is in direct contact with the recording medium feed roller 402, or in a state where a sheet of paper P is sandwiched between these rollers, the torque limiter 420 is slipped due to torque exceeding a torque limit, whereby the separating roller is rotated in accordance with the recording medium feed roller 402.

In a case where two or more sheets of paper P are sent out, the torque is within the torque limit due to friction between the sheets of paper P. Thus, the lower sheet(s) of paper P is returned to the upstream side by the separating roller 403, whereby the lower sheet(s) of paper P is prevented from being conveyed.

Reference numerals 425 and 426 denote conveyor rollers provided at a downstream side in the recording medium conveying direction.

Reference numeral 430 denotes a bottom plate provided at the bottom of the recording medium feed tray 40A so as to be able to move up and down. The bottom plate 430 lifts and lowers the stack of paper in the recording medium feed tray 40A.

When the recording medium feed tray 40A is installed at a predetermined position of the recording medium feed device 4A, the bottom plate 430 is lifted by a lifting and lowering unit (not shown) until the top face of the paper is detected by a recording medium detecting unit (not shown). On the contrary, when the recording medium feed tray 40A is drawn, the bottom plate 430 is lowered to a predetermined position.

The recording medium detecting unit is disposed such that the send-out roller 401 is brought into contact with the top face of the lifted paper at a predetermined position while applying pressure thereto.

Next, with reference to FIG. 5, a description will be given of a withdrawing mechanism to withdraw the send-out roller 401 from the top face of the paper, and of a releasing mechanism to release the separating roller 403 from contact with the recording medium feed roller 402, upon removal of the recording medium feed tray 40A.

FIG. 5 is a side view of the recording medium feed tray 40A as viewed in the direction of the arrow C in FIG. 2. FIG. 5 shows a state where the recording medium feed tray 40A is going to be installed to the recording medium feed device 4A.

First, a description will be given of the withdrawing mechanism which includes a withdrawing member 440, the roller supporting member 404, and the like.

The withdrawing member 440 is disposed at a front end portion of the recording medium feed tray 40A as viewed in the direction of installing the recording medium feed tray 40A. The withdrawing member 440 includes inclined surfaces 441 and 442 forming a symmetric inverse V-shape as viewed in a direction perpendicular to the direction of removing the recording medium feed tray.

As shown in FIGS. 2 and 3, the inclined surfaces 441 and 442 are designed so as to be brought into contact with the tip portions 405A and 406A of the left side plate 405 and the right side plate 406, respectively, at the time of removing the recording medium feed tray 40A.

A description will be given of a positional relationship in the vertical direction (height relationship) among the inclined surfaces 441 and 442, the tip portions 405A and 406A of the left side plate 405 and the right side plate 406, respectively, and the top face of the stack of paper P in the recording medium feed tray 40A.

Reference letter L denotes the top face of the paper P loaded up to the maximum number in the recording medium feed tray 40A. Reference letters M denote the lowermost points of the inclined surfaces 441 and 442, and reference letter N denotes the uppermost point of the inclined surfaces 441 and 442.

Note that the top face L herein shows a height of the paper P in a case where the bottom plate 430 is lowered to a predetermined position so that the paper can be loaded.

The tip portions 405A and 406A of the left side plate 405 and the right side plate 406, respectively, are in the same positions as viewed in the vertical direction. In addition, these positions of the tip portions 405A and 406A are positions in a case where the top plate 404A of the roller supporting member 404 is in contact with a stopper 427 (see FIG. 3), whereby rotation of the roller supporting member 404 is limited.

As shown in the drawing, the lowermost points M, tip portions 405A and 406A, top face L, and uppermost point N are positioned in this order as viewed from a lower position to an upper position.

In accordance with an operation of installing the recording medium feed tray 40A, the tip portion 405A is moved up while being in contact with the inclined surface 441 of the withdrawing member 440, whereby the roller supporting member 404 is rotated clockwise in FIG. 3.

After the tip portion 405A has passed through the uppermost point N, the roller supporting member 404 maintains a predetermined position (posture) at the uppermost point N due to an operation of the one-way clutch 408 (see FIG. 4).

Similarly, in accordance with an operation of drawing the recording medium feed tray 40A, the tip portion 406A is moved up along the inclined surface 442, whereby the roller supporting member 404 is operated as described above.

Next, a description will be given of the releasing mechanism including a releasing member 450, the separating roller supporting member 421, and the like.

The releasing member 450 is disposed on the right side face of the recording medium feed tray 40A as viewed in the direction of installing the recording medium feed tray 40A. The releasing member 450 includes inclined surfaces 451 and 452 forming a V-shape as viewed in a direction perpendicular to the direction of removing the recording medium feed tray.

When the recording medium feed tray 40A is brought to a position immediately before a predetermined installation position, a protruding portion 421A (see FIG. 3) of the separating roller supporting member 421 is brought into contact with the inclined surface 451 and thus lowered.

As a result, the separating roller supporting member 421 is rotated anticlockwise in FIG. 3, and the separating roller 403 is released from contact with the recording medium feed roller 402. The roller supporting member 404 in the predetermined position at the uppermost point N is rotated anticlockwise in FIG. 3, thereby being brought into contact with the top face L of the paper in the recording medium feed tray 40A.

When the recording medium feed tray 40A is installed further, the protruding portion 421A is moved up while being in contact with the inclined surface 452. Thus, the separating roller 403 is again brought into contact with the recording medium feed roller 402 while applying pressure thereto.

Here, bringing the separating roller 403 into contact with the recording medium feed roller 402 is completed immediately before the recording medium feed tray 40A is installed to a predetermined position of the recording medium feed device 4A.

Next, a description will be given of an operation of the recording medium feed device 4A in such a structure.

When the recording medium feed tray 40A with a stack of paper P loaded therein is installed, the roller supporting member 404 is rotated anticlockwise in FIG. 3 by the withdrawing member 440. Then, the one-way clutch 408 causes the roller supporting member 404 to maintain a predetermined position (posture) at the uppermost point N of the inclined surface 441 through.

The separating roller 403 is released from contact with the recording medium feed roller 402 due to an operation of the releasing member 450 immediately before the installation of the recording medium feed tray 40A is completed. The roller supporting member 404 is rotated anticlockwise in FIG. 3, and the tip portions 405A and 406A are brought into contact with the top face L as shown in FIG. 6.

A description will be given of a positional relationship among the tip portions 405A and 406A, the outer-circumferential surface of the send-out roller 401, and the top face of the paper.

In a case where sheets of paper are loaded up to the maximum number in the recording medium feed tray 40A and the bottom plate 430 is lowered to a predetermined position (the state shown in FIG. 6), the tip portions 405A and 406A are in contact with the top face L, and there is a space between the outer circumferential surface of the send-out roller 401 and the top face L.

In contrast, in a case where the bottom plate 430 is lifted, the top face of the paper is detected by the detecting unit, and the top face is in a predetermined position (recording medium feed position), the send-out roller 401 is in contact with the top face of the paper, while the tip portions 405A and 406A are not in contact with the top face.

As is clear from the drawing, even in a case where the number of sheets of paper is smaller than the maximum number, when the bottom plate 430 is lowered to a predetermined position, the tip portions 405A and 406A are in contact with the top face of the paper.

Returning to the description of the operation of the recording medium feed device, as the recording medium feed tray 40A is installed further, the separating roller 403 that has been released from contact is moved back along the inclined surface 452 of the releasing member 450 and is again brought into contact with the recording medium feed roller 402.

After the separating roller 403 is released from contact, the tip portions 405A and 406A are slipped along the top face L until the installation of the recording medium feed tray 40A is completed. A recording medium feeding operation is performed as follows after the installation of the recording medium feed tray 40A has been completed.

After the top face of the paper has been lifted up to a predetermined position by the lifting and lowering unit and the recording medium detecting unit, a recording medium feed start instruction is outputted from a control unit (not shown) of the image forming apparatus, and the one-turn clutch 411 is operated. The recording medium feed roller 402 and the send-out roller 401 start rotating, and, at the same time, the roller supporting member 404 is allowed to rotate anticlockwise in FIG. 3 by rotation of the recording medium feed roller shaft 407. Thus, the send-out roller 401 is always in contact with the top face of the paper P while applying pressure thereto.

Sheets of paper P sent out by the send-out roller 401 are separated into one sheet by the recording medium feed roller 402 and the separating roller 403, and then conveyed to the downstream side by the conveyor rollers 425 and 426.

When the sheet of paper P has been conveyed by a predetermined length by the conveyor rollers 425 and 426, the one-turn clutch 411 stops operating.

When the trailing edge of the sheet of paper P being conveyed has passed the send-out roller 401, the one-way clutch 410 enables the recording medium feed roller 402 to freely rotate in the recording medium conveying direction, and rotation of the send-out roller 401 is stopped. Thus, the subsequent sheet of paper is prevented from being sent out following the sheet of paper in front.

Next, a description will be given of an operation of the recording medium feed device 4A performed when the recording medium feed tray 40A is drawn.

Upon starting drawing the recording medium feed tray 40A, the bottom plate 430 is lowered to a predetermined position. Further, the separating roller 403 is released from contact with the recording medium feed roller 402 by the releasing member 450. The roller supporting member 404 is rotated anticlockwise in FIG. 3, whereby the tip portions 405A and 406A are brought into contact with the top face of the paper.

Thereafter, the recording medium feed tray 40A is drawn while the tip portions 405A and 406A are slipped along the top face of the paper. As the recording medium feed tray 40A is drawn further, the roller supporting member 404 is rotated to a predetermined position corresponding to the uppermost point N by the withdrawing member 440, and maintains the position (posture). Thus, the drawing operation is completed.

Next, when the recording medium feed tray 40A is to be installed again, the recording medium feed tray 40A is moved forward without the roller supporting member 404 receiving an operation of the withdrawing member 440, since the roller supporting member 404 is already rotated and withdrawn to the predetermined position. The separating roller 403 is released from contact with the recording medium feed roller 402 by the releasing member 450, and the recording medium feed device 4A repeats the above-described operation.

As described above, the send-out roller is withdrawn by the withdrawing mechanism at the time of removing the recording medium feed tray, and the send-out roller is not in contact with the top face of the recording media. Thus, the recording media loaded in the recording medium feed tray can be prevented from being displaced, thereby preventing the recording media from being torn or defectively conveyed.

Moreover, the recording medium holding member of a low friction coefficient which is formed integrally with the roller supporting member is allowed to be in contact with the top face of the recording media only at the time of removing the recording medium feed tray. Thus, the send-out roller, which is in general made of a material of a high friction coefficient such as rubber, can be prevented from contacting with the top face of the recording media, thereby preventing the recording media loaded in the recording medium feed tray from being displaced.

Even when the difference between the position of the top face of the recording media loaded up to the maximum number in the recording medium feed tray and the position of the top face of the recording media in a state of recording medium feeding is small due to downsizing of the recording medium feed device, the send-out roller can be prevented from contacting with the top face of the recording media by bringing the recording medium holding member into contact with the top face of the recording media at the time of removing the recording medium feed tray. Thus, even when the recording medium feed tray is drawn at the time of paper jam in a state where recording media are loaded up to the maximum number, the recording media can be prevented from being displaced.

Moreover, the send-out roller is always in contact with the top face of the recording media during installation of the recording medium feed tray. Thus, even when the recording media are wavy due to different degrees of shrinkage between the front and back sides of the respective recording media such as a sheet of paper already having an image formed on one side thereof (backside paper), and when there are gaps between the recording media, the gaps are eliminated and friction necessary for sending out the recording medium on the top is generated. Thus, a so-called “no feed,” where no recording medium is sent out, can be prevented.

The entire disclosure of Japanese Patent Application No. Tokugan 2004-039555 filed on Feb. 17, 2004 including specification, claims, drawings and summary are incorporated herein by reference in its entirety.

Claims

1. A recording medium feed device, comprising: a recording medium feed tray installable to and removable from a main body of the recording medium feed device; a send-out member to send out a recording medium loaded in the recording medium feed tray, the send-out member being in contact with a top face of the recording medium while applying pressure thereto at a time of installing the recording medium feed tray; and a withdrawing mechanism to withdraw the send-out member from the top face of the recording medium in the recording medium feed tray at a time of removing the recording medium feed tray.

2. The feed device of claim 1, further comprising: a recording medium feed member provided at a downstream side of the send-out member in a direction of sending out the recording medium; and a separating member to be in contact with the recording medium feed member while applying pressure thereto.

3. The feed device of claim 2, wherein the recording medium feed member is a recording medium feed roller, and the separating member is a separating roller.

4. The feed device of claim 1, wherein the send-out member is a send-out roller.

5. The feed device of claim 1, wherein the withdrawing mechanism moves the send-out member to a withdrawing position which is away from the top face of the recording medium in the recording medium feed tray in accordance with an operation of removing the recording medium feed tray, and moves the send-out member from the withdrawing position to the top face of the recording medium in the paper feed tray in accordance with an operation of installing the recording medium feed tray.

6. The feed device of claim 2, further comprising a releasing mechanism to release the separating member from the contact with the recording medium feed member in accordance with an operation of installing the recording medium feed tray.

7. The feed device of claim 6, wherein the releasing mechanism comprises a releasing member provided on the recording medium feed tray, to release the separating member from the contact with the recording medium feed member, and the releasing mechanism releases the separating member from the contact with the recording medium feed member by using the releasing member at the time of removing the recording medium feed tray.

8. A recording medium feed device, comprising: a recording medium feed tray installable to and removable from a main body of the recording medium feed device; a send-out roller to send out a recording medium loaded in the recording medium feed tray, the send-out roller being in contact with a top face of the recording medium while applying pressure thereto at a time of installing the recording medium feed tray; a roller supporting member to rotatably support the send-out roller; and a withdrawing member provided on the recording medium feed tray, to rotate the roller supporting member in a direction of withdrawing the send-out roller from the top face of the recording medium in the recording medium feed tray in accordance with an operation of removing the recording medium feed tray.

9. The feed device of claim 8, further comprising: a recording medium feed roller provided at a downstream side of the send-out roller in a direction of sending out the recording medium; and a separating roller to be in contact with the recording medium feed roller while applying pressure thereto.

10. The feed device of claim 8, wherein the roller supporting member is held by a rotary shaft of the recording medium feed roller via a one-way clutch to which the rotary shaft is connected when the rotary shaft is rotated in a direction opposite to a direction of sending out the recording medium.

11. The feed device of claim 10, wherein the withdrawing member rotates the roller supporting member around the rotary shaft via the one-way clutch in the direction of withdrawing the send-out roller from the top face of the recording medium in the recording medium feed tray in accordance with the operation of removing the recording medium feed tray.

12. The feed device of claim 9, further comprising a releasing mechanism to release the separating roller from the contact with the recording medium feed roller in accordance with an operation of installing the recording medium feed tray.

13. The feed device of claim 12, wherein the releasing mechanism comprises a releasing member provided on the recording medium feed tray, and the releasing mechanism releases the separating roller from the recording medium feed roller by using the releasing member at a time of removing the recording medium feed tray.

14. The feed device of claim 13, wherein the releasing mechanism releases the separating roller from the recording medium feed roller by moving a roller supporting member supporting the separating roller.

15. A recording medium feed device, comprising: a recording medium feed tray installable to and removable from a main body of the recording medium feed device; a send-out roller to send out a recording medium loaded in the recording medium feed tray, the send-out roller being in contact with a top face of the recording medium while applying pressure at a time of installing the recording medium feed tray; and a recording medium holding member formed integrally with the send-out roller, to be in contact with the top face of the recording medium in the recording medium feed tray only at a time of removing the recording medium feed tray.

16. The feed device of claim 15, further comprising: a recording medium feed roller provided at a downstream side of the send-out roller in a direction of sending out the recording medium; and a separating roller to be in contact with the recording medium feed roller while applying pressure thereto.