JP2008184247A - Sheet feeder and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet feeder provided with a sheet size detector capable of inexpensively detecting attachment of a regulation unit for an auxiliary sheet, and to provide an image forming device. <P>SOLUTION: A position of a small size of sheet incapable of regulating a position by regulation members 21a, 21b, 23 is regulated by the regulation unit 30 for the auxiliary sheet attached detachably to a sheet storage part 2. The attachment of the regulation unit 30 for the auxiliary sheet is detected by a sheet size detecting part 27, by moving a detected part 32 to a position detected by the sheet size detecting part 27 while interlocked with the attachment of the regulation unit 30 for the auxiliary sheet, when attaching the regulation unit 30 for the auxiliary sheet. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sheet feeding apparatus and an image forming apparatus, and more particularly to a sheet feeding apparatus and an image forming apparatus that include a sheet size detecting device that detects the size of a sheet according to the position of a regulating unit that regulates the position of a sheet stored in a sheet storage unit. .

  2. Description of the Related Art Today, image forming apparatuses such as copying machines, printers, and facsimiles are widely used in which an image is formed by feeding a sheet from a sheet feeding apparatus to an image forming unit. As such a sheet feeding apparatus, a sheet feeding cassette as a sheet storage unit is detachably attached to the apparatus main body, and sheets stored in the sheet feeding cassette are automatically fed to the image forming unit. It is common.

  As a sheet feeding cassette used in such a sheet feeding apparatus, a sheet feeding direction rear end (hereinafter referred to as a rear end) of a sheet stored in a sheet storing unit so that sheets of different sizes can be stored. A rear end regulating member for regulating the position is provided. Further, a side end regulating member that regulates a side end position of a sheet in a direction orthogonal to the sheet feeding direction (hereinafter referred to as a width direction) is provided.

  In such a sheet feeding cassette, the side edge of the sheet is regulated by the side edge regulating member, while the trailing edge is regulated by the trailing edge regulating member so that the leading edge position of the sheet is always regulated to a predetermined position. ing. As a result, when the sheet feeding cassette is stored in the apparatus main body, stable sheet feeding can be performed regardless of the sheet size.

  Incidentally, some conventional sheet feeding apparatuses having such a sheet feeding cassette include a sheet size detecting apparatus for detecting the size of the sheets stacked on the sheet feeding cassette. As such a sheet size detection apparatus, for example, a multiple switch is provided in the apparatus main body, and the multiple switch is selectively turned ON / OFF by a switch member that moves together with the rear end regulating member so as to detect the sheet size. I have to.

  By the way, in recent years, in an image forming apparatus such as a laser beam printer, an image is formed on a small size sheet having an irregular sheet size, which is not a standard sheet size such as a 4 × 6 inch size sheet or a postcard size sheet. The demand to do is increasing.

  However, when such a small size sheet is set in the sheet feeding cassette, the small size sheet comes to be located outside the movement range of the side end regulating member and the rear end regulating member. For this reason, when a small sized sheet is set in the sheet feeding cassette, the position of the sheet cannot be regulated by the side edge regulating member and the trailing edge regulating member.

  Therefore, in order to regulate the position of a small-sized sheet that cannot be regulated by the regulating member as described above, a special cassette is detachably attached to the sheet feeding cassette as an auxiliary sheet regulating unit. Yes (see Patent Document 1 or 2). Then, by restricting the position of the small size sheet by such a dedicated cassette, it is possible to meet the demand for image formation for the small size sheet.

Japanese Patent Laid-Open No. 3-166134 Japanese Utility Model Publication No. 4-127736

  However, in such a conventional image forming apparatus, as described above, since the small size sheet is located outside the movement range of the rear end regulating member, when the dedicated cassette for the small size sheet is attached, the rear end regulating member Does not correspond to the sheet size. For this reason, when a dedicated cassette is attached, if the sheet size is determined according to the position of the trailing edge regulating member, there is a problem in that the sheet size does not match the image and a jam occurs.

  Here, in order to solve such a problem, for example, another detection sensor for detecting whether or not a dedicated cassette is attached is provided. When this separate detection sensor detects the attachment of the dedicated cassette, the sheet size may be determined regardless of the position of the rear end regulating member. However, when another detection sensor is provided in this way, the cost increases.

  Therefore, the present invention has been made in view of such a current situation, and a sheet feeding device provided with a sheet size detection device capable of detecting the attachment of a dedicated cassette (auxiliary sheet regulating unit) at low cost, and An object of the present invention is to provide an image forming apparatus.

  The present invention provides a sheet size detection unit in the apparatus main body, and the sheet according to the position of a regulating member that regulates the position of the sheet stored in the sheet storage unit when the sheet storage unit is attached to the apparatus main body. In the sheet feeding device including a sheet size detection device that detects the size of the sheet stored in the sheet storage unit by a size detection unit, a regulation unit that is detachably mounted on the sheet storage unit and regulates the position of the sheet An auxiliary sheet restriction unit, and a detected portion that is provided in the sheet storage portion and interlocks with the attachment of the auxiliary sheet restriction unit when the auxiliary sheet restriction unit is attached. The sheet size detection unit detects the detection unit to detect attachment of the auxiliary sheet regulating unit to the sheet storage unit. It is.

  According to the present invention, when the auxiliary sheet restriction unit is attached, the attachment of the auxiliary sheet restriction unit can be detected at a low cost by detecting the attachment of the auxiliary sheet restriction unit by the sheet size detection unit.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating an overall configuration of a laser beam printer (LBP) which is an example of an image forming apparatus including a sheet feeding device according to an embodiment of the present invention.

  In FIG. 1, reference numeral 1 denotes a laser beam printer, and 1A denotes a laser beam printer main body (hereinafter referred to as a printer main body). The printer main body 1A includes an image forming unit 1B, and a sheet feeding unit for feeding sheets S such as recording sheets stacked and stored in the paper feed cassette 2 to the image forming unit 1A at the lower part of the printer main body 1A. A device 1C is provided.

  Here, the image forming unit 1B exposes the surface of the process cartridge 7 including the photoconductive drum 7a, the charger 7b, the developing sleeve 7c, the cleaner 7d, and the like, and the surface of the photoconductive drum 7a so as to be static on the photoconductive drum 7a. And a laser scanner 8 as exposure means for forming an electrostatic latent image.

  Further, the printer main body 1A includes a transfer roller 9 that is in contact with the photosensitive drum 7a and forms a transfer unit together with the photosensitive drum 7a, a fixing unit 10 that fixes the toner image transferred by the transfer unit to the sheet S, and the like. Yes.

  Note that the sheet feeding apparatus 1C separates and conveys the pickup roller 3 that feeds the sheets S stacked in the sheet feeding cassette 2 that is a sheet storage unit from the uppermost side, and the sheet S that is sent out by the pickup roller 3 one by one. A retard roller pair 4a, 4b is provided. The printer main body 1A also serves as the apparatus main body of the sheet feeding apparatus 1C.

  Next, an image forming operation in the laser beam printer 1 configured as described above will be described.

  When the image forming operation is started, first, the photosensitive drum 7a is rotated in the direction of the arrow, and the surface is charged by the charger 7b. Thereafter, the laser drum 8a is subjected to a laser based on image information from the laser scanner 8. Light is emitted. Thereby, an electrostatic latent image is formed on the photosensitive drum.

  Next, the electrostatic latent image is developed as a toner image when toner that has been appropriately charged with the rotation of the developing sleeve 7c is supplied onto the photosensitive drum 7a and adheres to the electrostatic latent image. Visualized.

  On the other hand, the pickup roller 3 rotates in parallel with such a toner image forming operation, and sends the uppermost sheet S on the paper feed cassette 2. Then, the sheet S sent out by the pickup roller 3 in this way is conveyed by the retard roller pair 4a, 4b, and the leading edge position alignment (skew correction) is performed by the stopped registration roller pair 6.

  Next, the sheet S is conveyed to the transfer unit by the registration roller pair 6 so as to be synchronized with the image formed on the photosensitive drum 7a in the image forming unit 1B, and the image on the photosensitive drum 7a is transferred by the transfer roller 9 to the sheet S. Is transcribed.

  Next, the sheet S on which the toner image is transferred in this manner is conveyed to a fixing nip constituted by a heating roller 10a and a pressure roller 10b provided in the fixing unit 10, where the unfixed toner image is heated and Pressurized and fixed on the sheet surface. The sheet S after the toner image is fixed in this way is discharged onto the paper discharge tray 12 by the paper discharge roller 11.

  By the way, the paper feed cassette 2 is detachably attached to the printer main body 1A. 2A shows a state in which the paper feed cassette 2 is housed in the printer main body 1A, and FIG. 2B shows a state in which the paper feed cassette 2 is pulled out from the printer main body 1A. Show. Here, the sheet feeding cassette 2 includes a cassette body 2A for stacking and storing sheets of various sizes, and an intermediate plate 22 on which the sheet S is stacked so as to be pivotable in the vertical direction.

  FIG. 3 is a view showing the inside of the paper feed cassette 2. In FIG. 3, reference numeral 25 denotes a lift plate that is rotated in the vertical direction by a drive source (not shown) provided in the printer body. Thus, the middle plate 22 is configured to rotate in the vertical direction. When the paper feed cassette 2 is pulled out from the printer main body 1A, the connection with the drive source is released, and the lift plate 25 is lowered due to its own weight and the weight of the intermediate plate 22, so that the intermediate plate 22 is also shown in FIG. It descends from the upper rotation position where the feeding is possible.

  The sheet feeding cassette 2 includes a pair of side regulating members 21a and 21b that are examples of regulating members that regulate the side edge position of the sheet, and a trailing edge regulating member that is an example of a regulating member that regulates the trailing edge position of the sheet. 23.

  Here, the side restricting members 21a and 21b and the rear end restricting member 23 are configured to be movable according to the sheet size, and the side restricting members 21a and 21b are moved in the opposite directions by the pinion 24. It is like that. 3A shows the position of the rear end regulating member 23 when the sheet size is A4 size, and FIG. 3B shows the position of the rear end regulating member 23 when the sheet size is A5 size. Indicates the position.

  In FIG. 3, reference numeral 27 denotes a size detection switch unit that is provided in the printer main body 1 </ b> A and detects a size of a sheet stored in the paper feed cassette 2. In the present embodiment, the size detection switch unit 27 includes three switches SW1 to SW3 arranged in the vertical direction as shown in Table 1 described later.

  Reference numeral 26 denotes a size detection member that turns on and off the three switches SW <b> 1 to SW <b> 3 according to the sheet size. The size detection member 26 is engaged with the rear end regulating member 23. Further, the size detection member 26 is formed with a plurality of openings 26a that are formed at positions corresponding to the sheet size and selectively turn ON / OFF the switches SW1 to SW3. The size detection member 26 and the size detection switch unit 27 constitute a sheet size device that detects the size of the sheet stored in the paper feed cassette 2.

  Next, sheet size detection by the sheet size apparatus having such a configuration will be described.

  First, when a sheet is stored in the cassette body 2A, the rear end regulating member 23 is moved according to the size so as to regulate the position of the sheet. Here, when the rear end regulating member 23 is moved in this way, the size detecting member 26 is moved integrally with the rear end regulating member 23. Accordingly, a predetermined opening 26a formed at a position corresponding to the sheet size among the plurality of openings 26a moves to a position facing the three switches SW1 to SW3.

  When the paper feed cassette 2 is inserted in this state, as shown in FIG. 3, the predetermined opening 26a comes to face the three switches SW1 to SW3, so that the three switches SW1 to SW3 are selectively turned ON / OFF. To do.

  Here, a control unit (not shown) is provided in the printer main body 1A, and ON / OFF signals of the three switches SW1 to SW3 are input to the control unit. The control unit detects the standard sheet size and the irregular sheet size based on the ON / OFF signals of the switches SW1 to SW3 and the following Table 1 stored in a memory (not shown). .

  In the present embodiment, the switches SW1 to SW3 are turned on when pressed by the size detection member 26, and are turned off when the switches SW1 to SW3 are not pushed facing the opening 26a. Further, by turning these three switches SW1 to SW3 ON / OFF, the sheet size can be detected with an error range of about ± 3 mm with respect to the length of each sheet.

  Note that, between the standard sheet sizes, that is, when all of the switches SW1 to SW3 are ON, it is detected as an irregular size. When an image is formed on such an irregular size sheet, the user inputs the sheet size through an input unit (not shown) provided in the printer main body 1A. The control unit performs sheet feeding and image forming operations based on the values.

  By the way, in the present embodiment, when the user prints, for example, on a postcard, the sheet cassette 2 having such a configuration has a postcard dedicated cassette 30 as an auxiliary sheet regulating unit as shown in FIG. The plate 22 is detachably mounted. The postcard cassette 30 can accommodate 4 × 6 inch size sheets and other small size sheets.

  In FIG. 4, reference numeral 22 a denotes a locking opening formed in the intermediate plate 22 so as to be locked with a locking claw 30 a provided on the bottom surface of the postcard dedicated cassette 30. When the postcard dedicated cassette 30 is detachably attached to the middle plate 22, the locking claw 30a is locked to the locking opening 22a. Reference numeral 30b denotes a side end restricting portion for restricting the side end position in the width direction of the sheet stored in the postcard dedicated cassette 30, and 30c denotes a rear end restricting portion for restricting the rear end position of the sheet.

  As shown in FIG. 5, a link member 31 is swingably provided on the bottom surface of the paper feed cassette 2. Here, a protrusion 31a protrudes from one end of the link member 31, and a detected portion that turns on / off the three switches SW1 to SW3, similarly to the size detection member 26, at the other end. The detection member 32 is engaged. The detection member 32 is slidably attached to the side surface of the paper feed cassette 2 and is urged by a spring 33.

  When the postcard cassette 30 is attached to the intermediate plate 22 as shown in FIG. 4, the postcard cassette 30 and the projection 31a are engaged, and together with the postcard cassette 30, the link member 31 is attached as shown in FIG. Swings. Further, when the link member 31 swings in this way, the detection member 32 is detected by the position where the three switches SW1 to SW3 are turned on / off while resisting the spring 33 via the link member 31, that is, the size detection switch unit 27. Slide to the desired position.

  When the paper feed cassette 2 is inserted into the printer main body in this state, the three switches SW1 to SW3 are not in the above-described Table 1, and SW1 is ON, SW2 is ON, and SW3 is OFF. Then, based on such ON / OFF signals of the switches SW1 to SW3 and Table 1, the control unit determines that the postcard size dedicated cassette 30 is mounted. In other words, it is determined that a postcard or a small size sheet is stored in the paper feed cassette 2.

  As described above, when the postcard cassette is mounted, the size detection switch unit 27 moves the detection member 32 to a position detected by the size detection switch unit 27 in conjunction with the postcard cassette mounting. Can be detected.

  By the way, when the postcard cassette 30 is mounted on the middle plate 22, the middle plate 22 is in the downward rotation position shown in FIG. The plate 22 rotates upward. At this time, the postcard-dedicated cassette 30 also rotates integrally with the intermediate plate 22, but when the postcard-dedicated cassette 30 rises in this way, the engagement with the postcard-dedicated cassette 30 is released.

  When the engagement with the postcard-dedicated cassette 30 is released in this way, the link member 31 and the detection member 32 are returned to the position before the postcard-dedicated cassette 30 is mounted by the spring 33 (see FIG. 5). . Here, when the link member 31 returns to the position before the postcard cassette is mounted in this way, the detection member 32 is not detected by the size detection switch unit 27.

  In order to prevent this, in the present embodiment, as shown in FIG. 7, the detection member 32 and the switch holding member 28, which is a main body of the detection unit including the size detection switch unit 27, are respectively engaged with the engagement portions 32 a. , 28a are formed. The switch holding member 28 is rotatably attached to the cassette body 2A via a shaft 28b and is urged toward the inside of the cassette body by a biasing member such as a spring (not shown).

  Thus, when the postcard-dedicated cassette 30 is mounted on the intermediate plate 22 and the detection member 32 slides via the link member 31, the switch holding member 28 is pressed by the detection member 32 and resists an urging member such as a spring. Rotate. Thereafter, the engaging portion 32a of the detection member 32 and the engaging portion 28a of the switch holding member 28 are engaged. After the detection member 32 slides, the switch holding member 28 is manually rotated against the spring, and then the engagement portion 32a of the detection member 32 and the engagement portion 28a of the switch holding member 28 are engaged. You may comprise so that it may match.

  Then, by engaging the detection member 32 and the switch holding member 28 in this way, the detection member 32 can be held at a position detected by the size detection switch unit 27 even when the intermediate plate 22 is raised. .

  In this manner, when the postcard cassette 30 is mounted, the conventional size detection switch unit 27 detects the mounting of the postcard cassette 30 to detect the mounting of the postcard cassette 30 without adding a new detection sensor. Can be detected at low cost.

  In the above description, a detection pattern is provided only when the postcard cassette 30 is mounted. However, in addition to the above-mentioned size, it may be necessary to support an 11 × 14 inch sheet. In this case, when the detection pattern is insufficient, the detection pattern of the detection member 32 may be the same as the irregular size. In this case, paper is fed according to the postcard size input by the user.

  Further, in the above description, when the middle plate 22 rotates upward, the detection member 32 and the switch holding member 28 are related as a holding unit that holds the detection member 32 at a position detected by the size detection switch unit 27. Joint portions 32a and 28a are formed. However, the present invention is not limited to this, and a locking portion may be provided on at least one of the detection member 32 and the switch holding member 28.

1 is a diagram illustrating an overall configuration of a laser beam printer (LBP) that is an example of an image forming apparatus including a sheet feeding device according to an embodiment of the present invention. FIG. 4A is a diagram showing a state of a paper feed cassette that is detachably attached to the printer main body of the laser beam printer, and FIG. 5B is a diagram showing a state of being pulled out from the printer main body. (A) of the sheet feeding cassette 2 is a diagram showing the position of the trailing edge regulating member when the sheet size is A4 size, and (b) is a diagram showing the position of the trailing edge regulating member when the sheet size is A5 size. . The figure which shows a mode that the postcard exclusive cassette is mounted | worn on the middle plate of the said paper feed cassette. The figure which shows the relationship between the link member and detection member which were provided in the said paper feed cassette. The figure which shows the relationship between a link member and a detection member when the cassette for postcards is mounted on the middle plate of the paper feed cassette. The perspective view which shows the state of a paper feeding cassette when the said center board rotates upwards.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser beam printer 1A Laser beam printer main body 1B Image formation part 1C Sheet feeding apparatus 2 Paper feed cassette 2A Cassette main body 21a, 21b Side restriction member 22 Middle plate 23 Rear end restriction member 27 Size detection switch part 28 Switch holding member 28a Switch Holding member engaging portion 30 Postcard dedicated cassette 30b Side end regulating portion 30c Rear end regulating portion 31 Link member 32 Detection member 32a Detection member engagement portion S Sheet SW1 to SW3 switch

Claims (6)

A sheet size detection unit is provided in the apparatus main body, and when the sheet storage unit is mounted on the apparatus main body, the sheet size detection unit is configured to control a position of a sheet stored in the sheet storage unit according to a position of a regulating member. In the sheet feeding device including a sheet size detection device that detects the size of the sheet stored in the sheet storage unit,
Auxiliary sheet regulating unit that is detachably attached to the sheet storage unit and includes a regulating unit that regulates the position of the sheet;
A detected portion that is provided in the sheet storage unit and interlocks with the mounting of the auxiliary sheet regulating unit when the auxiliary sheet regulating unit is mounted;
The sheet feeding device according to claim 1, wherein the sheet size detecting unit detects the detected portion to detect attachment of the auxiliary sheet regulating unit to the sheet storage unit. The auxiliary sheet regulating unit is detachably mounted on an intermediate plate provided in the sheet storage portion so as to be able to stack and move in the vertical direction.
The middle plate has a downward rotation position for mounting the auxiliary sheet regulating unit and an upper position where the sheet whose position is regulated by the auxiliary sheet regulating unit mounted on the middle plate can be fed. The sheet feeding apparatus according to claim 1, wherein the sheet feeding apparatus is movable between the rotation positions. When the auxiliary sheet regulating unit is mounted on the intermediate plate at the downward rotation position, the auxiliary sheet regulating unit is engaged with the auxiliary sheet regulating unit and moved to move the detected portion. A link member that is moved to a position that is detected by the sheet size detection unit, and is disengaged from the auxiliary sheet regulating unit when the intermediate plate is rotated upward;
A holding portion for holding the detected portion moved by the link member when the intermediate plate is rotated upward;
The sheet feeding apparatus according to claim 2, further comprising:   4. The sheet feeding apparatus according to claim 3, wherein the holding unit is a detection unit main body provided with the sheet size detection unit and a locking unit provided on at least one of the detected unit.   The sheet size detection unit can detect a standard sheet size and an irregular sheet size, and when the sheet size detection unit detects the attachment of the auxiliary sheet regulation unit, the sheet size detection unit causes the sheet to be detected by the sheet size detection unit. 5. The sheet feeding device according to claim 1, wherein the storage unit detects that an irregular sheet size is stored. 6.   An image forming apparatus comprising: an image forming unit; and a sheet feeding device according to claim 1 for feeding a sheet to the image forming unit.

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