JP2004106982A - Paper feeding cassette - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shrinkable paper feeding cassette capable of surely detecting a sheet size even when a position of a guide is changed under a condition that an auxiliary frame is pulled to a main frame. <P>SOLUTION: This paper feeding cassette 22 has a main frame 32, and an auxiliary frame 34 slidable against the main frame 32. A rear end guide 76 slidable against the auxiliary frame 34 is installed to the auxiliary frame 34. The rear end guide 76 is connected with a slide piece 98 via a first gear 84, a second gear 94, and a rack part 102. In this slide piece 98, a detection cam 104 moves, interlocking with the auxiliary frame 34 and the rear end guide 76, and is detected by a switch 108 so as to recognize a sheet size. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sheet cassette, for example, to a sheet cassette used in an image forming apparatus.
[0002]
2. Description of the Related Art As a paper feed cassette of an image forming apparatus, a main frame and an auxiliary frame slidably provided on the main frame are provided. Stretching is known. Also, a rear end guide is slidably provided on the auxiliary frame body, and the rear end guide is slid according to the sheet size in a state where the auxiliary frame body is most pressed into the main frame body. There are also known ones that can handle the sheet size. Further, it is also known to detect a sheet size in this type of telescopic cassette (see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-11-139572
[Problems to be solved by the invention]
In the above-described conventional example, it is most difficult to slide the rear end guide according to the sheet size in a state where the auxiliary frame is pressed into the main frame most, and to pull out the auxiliary frame to the main frame. It is assumed that a sheet having a large sheet size that cannot be accommodated in the pushed state is accommodated. For this reason, the sheet detection is performed separately by the first detecting means for detecting the position of the rear end guide with respect to the main frame and the second detecting means for detecting the position of the auxiliary frame with respect to the main frame. It is.
However, even when the auxiliary frame is pulled out from the main frame, the rear end guide may be slid with respect to the auxiliary frame to increase the degree of freedom corresponding to the sheet size. In such a case, in the above conventional example, there is a problem that the sheet size cannot be detected because the first detecting means and the second detecting means are not linked.
The present invention can reliably detect the sheet size even if the position of the guide is changed in a state where the auxiliary frame is pulled out with respect to the main frame in the telescopic paper feed cassette. It is intended to provide a paper feed cassette.
[0006]
In order to achieve the above object, the present invention is characterized by a main frame, an auxiliary frame slidably provided with respect to the main frame, and a main frame. There is provided a sheet feeding cassette having a guide slidably provided on an auxiliary frame, and a detecting means connected to the auxiliary frame and the guide for detecting a position of the guide with respect to the main frame. Therefore, since the detection means connected to the auxiliary frame and the guide plate is provided, even when the auxiliary frame is pulled out with respect to the main frame, the position of the guide relative to the main frame, that is, the sheet size can be changed. Can be detected.
It is preferable that the detecting means has a detecting cam interlocked with the auxiliary frame and the guide, and the switch is operated by the detecting cam. As described above, by linking the detection cam with the auxiliary frame and the guide, it is possible to detect the sheet size with one switch.
Further, it is preferable that the detection cam is constituted by a set of a plurality of cam surfaces having different shapes. This makes it possible to easily detect the position of the detection cam. It is further preferable to combine a detection cam having a plurality of cam surfaces having different shapes and a switch having at least three identification means. If the switch has, for example, three identification units, eight combinations of sheet sizes can be detected by a combination of the identification units.
It is preferable that an actuator is interposed between the detection cam and the switch. Even if the height of the cassette changes according to the sheet capacity of the paper cassette, it is possible to change the position of the switches on the paper supply unit main body by appropriately selecting the actuator length. Can be handled.
Further, the detecting means includes a first gear which is formed with a cam portion with which a pin provided on the guide is slidably abutted, and which is rotatably supported by the auxiliary frame body; A second gear meshing with the first gear and rotatably supported by the auxiliary frame; and a rack portion meshing with the second gear are provided and slidably supported by the auxiliary frame. Preferably, a sliding piece is provided, and the detecting cam is provided on the sliding piece. By configuring the gears in this way, the movement of the guide can at least accurately detect the position.
[0011]
Embodiments of the present invention will now be described with reference to the drawings.
FIG. 1 shows an outline of an image forming apparatus 10 according to an embodiment of the present invention. The image forming apparatus 10 has an image forming apparatus main body 12, an image forming unit 14 is mounted in the image forming apparatus main body 12, and a discharge unit 16 described later is provided above the image forming apparatus main body 12. At the same time, for example, two-stage paper feed units 18 are arranged below the image forming apparatus main body 12. Further, below the image forming apparatus main body 12, two-stage paper feed units 18, 18 which are detachably mounted as options are arranged.
Each paper feed unit 18 has a paper feed unit main body 20 and a paper feed cassette 22 for storing paper. The paper feed cassette 22 is slidably mounted on the paper feed unit main body 20, and is pulled out in a front direction (right direction in FIG. 1). Further, a nudger roll 24 is disposed in the upper portion near the inner end of the paper feed cassette 22, and a retard roll 26 and a feed roll 28 are disposed in front of the nudger roll 24. Further, the optional paper feed units 18 are provided with a pair of feed rolls 30, respectively.
At least one of the plurality of paper feed cassettes 22 is extendable and contractable, and has a main frame 32 and an auxiliary frame 34 slidably provided with respect to the main frame 32. As shown by a two-dot chain line in FIG. 1, when the auxiliary frame 34 is extended, the auxiliary frame 34 protrudes from the image forming apparatus main body 12 in the front direction by at least a length A that is a part of the auxiliary frame 34, When contracted, the front wall of the main body 12 of the image forming apparatus is made to coincide with the front wall. This paper feed cassette 22 will be described later in detail.
The transport path 36 is a paper path from the nager roll 24 of the lowermost sheet feed unit 18d to the discharge port 38. The transport path 36 is located on the back surface of the image forming apparatus main body 12 (left side in FIG. 1). ) Near the feed roller 30 of the lowermost sheet feeding unit 18 to a fixing device 62 to be described later. A transfer device 56 and an image carrier 54, which will be described later, are arranged on the upstream side of the fixing device 64 in the transport path 36, and a registration roll 40 is arranged on the upstream side of the transfer device 62 and the image carrier 54. Further, a discharge roll 42 is disposed near the discharge port 38 of the transport path 36.
Accordingly, the sheet conveyed from the sheet supply unit 18 is temporarily stopped by the registration roll 40 in the conveyance path 36 and sent to the image forming means 14 at a predetermined timing to form an image. Is discharged to the discharge unit 16.
However, in the case of double-sided printing, it is returned to the reversing path. That is, the front of the discharge roll 42 is divided into two forks, a switching claw 44 is provided at the divided portion, and a reversing path 46 returning from the divided portion to the registration roll 42 is formed. The reversing path 46 is provided with conveying rollers 48a to 48c. In the case of double-sided printing, the switching claw 44 is switched to the side where the reversing path 46 is opened, and the discharge roll 42 is moved toward the rear end of the sheet. The recording medium is guided to the reversing path 46, and is discharged to the discharge unit 16 through the registration roll 38, the transfer device 62, the image carrier 54, and the fixing device 64.
The discharge section 16 has an inclined section 50 that is rotatable with respect to the image forming apparatus main body 12. The inclined portion 50 has a lower outlet portion and is inclined so as to gradually increase toward the front (rightward in FIG. 1), with the outlet portion as the lower end and the raised tip as the upper end. The inclined portion 50 is supported by the image forming apparatus main body 12 so as to be rotatable about a lower end. As shown by a two-dot chain line in FIG. 1, when the inclined portion 50 is rotated upward and opened, an open portion 52 is formed, and a process cartridge 66 described later can be attached and detached via the open portion 52. .
The image forming means 14 is of an electrophotographic type, for example, and includes an image carrier 54 made of a photoreceptor, a charging device 56 made of, for example, a charging roll for uniformly charging the image carrier 54, An optical writing device 58 for writing a latent image by light on the image carrier 54 charged by 56, a developing device 60 for visualizing the latent image of the image carrier 54 formed by the optical writing device 58 with a developer, A transfer device 62 formed of, for example, a transfer roll for transferring the developer image by the developing device 60 onto a sheet, a cleaning device 63 formed of, for example, a blade for cleaning the developer remaining on the image carrier 54, and a transfer device 62 for transferring the developer image. The fixing device 64 includes, for example, a pressure roll and a heating roll for fixing the developer image on the sheet to the sheet. The optical writing device 58 is composed of, for example, a scanning type laser exposure device, is disposed near the front of the image forming apparatus main body 12 in parallel with the above-mentioned sheet feeding unit 18, and exposes the image carrier 54 across the inside of the developing device 60. . The developing device 60 has a developing roll 66 facing the image carrier 54.
The process cartridge 68 integrates the image carrier 54, the charging device 56, the developing device 60, and the cleaning device 64. The process cartridge 68 is disposed immediately below the inclined portion 50 of the discharge portion 16 and is detached via the opening 52 formed when the inclined portion 50 is opened as described above.
FIGS. 2 to 5 show an example of the paper feed cassette 22. FIG. The main frame 32 supports the above-described retard roll 26 on the back side in the insertion direction of the sheet cassette 22. The main frame 32 is provided with a vertically movable sheet stacking plate 70 for stacking sheets, and the sheet stacking plate 70 rises in accordance with the remaining amount of sheets. The side of the auxiliary frame 34 is slidably inserted into the side of the main frame 32. A lock groove 72 is formed in the auxiliary frame 34 in the front-rear direction. For example, three engagement portions 74 are formed in the lock groove 72, and the engagement portion 74 is slidable on the main frame 32. Are engaged with each other, so that the auxiliary frame 34 is fixed in three stages, for example, by expansion and contraction.
A rear end guide 76 for guiding the rear end of the sheet is disposed in the auxiliary frame 34. The rear end guide 76 is engaged with a guide groove 78 formed in the auxiliary frame 34. It is erected movably in the front-rear direction. The rear end guide 76 is provided with, for example, two lock release pieces 80. The lock of the rear end guide 76 is released by sliding the lock release pieces 80 inward against an elastic body (not shown), The rear end guide 76 can be moved along the guide groove 78. A first engagement pin 82 protrudes from the rear end guide 76. The engagement pin 82 protrudes toward the back surface of the auxiliary frame 34, and a first cam portion 86 formed on the first gear 84. Is engaged.
The first gear 84 is composed of, for example, a large spur gear, and is rotatably supported by a first support shaft 88 provided on the auxiliary frame 34. The first gear 84 is provided with a first cam portion 86 and a second cam portion 90. The first cam portion 84 is formed in a groove shape so that the first gear 84 can be changed in magnification and rotated in accordance with the reciprocation of the rear end guide 76. Further, the second cam portion 90 is engaged with a second engagement pin 92 protruding from the auxiliary frame body 34, and the first gear 84 is surely rotated about the first support shaft 88. And the rotation range of the first gear 84 is regulated.
At the end of the first gear 84, arc-shaped teeth centering on the first support shaft 88 are formed, and the second gear 94 meshes with these teeth. The second gear 94 is an idle gear, and rotates around a second support shaft 96 formed to project from the auxiliary frame 34. The rack portion 102 of the sliding piece 98 meshes with the second gear 94.
The sliding piece 98 is supported by a third engaging pin 100 formed on the auxiliary frame 34 so as to be slidable with respect to the auxiliary frame 34, and is provided on one surface of the sliding piece 98. A rack 102 is formed and meshes with the second gear 94, and a detection cam 104 is formed on the other surface of the sliding piece 98. The detection cam 104 is constituted by a set of a plurality of (four in this embodiment) cam surfaces having different shapes. The main frame 32 is provided with, for example, an actuator 106 facing the detection cam 104. The actuator 106 is made of, for example, three plate-like members, and projects to the side surface of the main frame 32 when the cam surface of the detection cam 106 abuts. A switch 108 is provided in the sheet feeding unit main body 20 (FIG. 1) so as to face the actuator 106. The switch 106 is a micro switch having, for example, three actuators to be turned on and off, and constitutes three identification means. As described above, since the switch 108 has three identification means, a maximum of eight positions can be detected by changing the shape of the detection cam 104.
Next, the operation of the above embodiment will be described.
The image carrier 54 is uniformly charged by the charging device 56, and the charged image carrier 54 is irradiated with light emitted from the optical writing device 58 based on the image signal to form a latent image. The latent image on the image carrier 54 formed by the optical writing device 58 is visualized by the developer of the developing device 60.
On the other hand, one of the paper feeding units 18 is selected by a size signal or the like, and the sheets stored in one of the paper feeding cassettes 22 are sent out by a nager roll 24 and separated by a retard roll 26 and a feed roll 28. The transfer roller 62 reaches the registration roll 40, is temporarily stopped by the registration roll 40, and is guided between the transfer device 62 and the image carrier 54 in a timely manner.
When the recording medium is guided between the transfer device 62 and the image carrier 54 in this manner, the developer on the image carrier 54 is transferred to the recording medium by the transfer device 62. The sheet onto which the developer has been transferred is discharged to the discharge unit 16 through the fixing device 64.
In the paper feed cassette 22, the size of the stored sheets is detected. The rear end of the sheet is in contact with the rear end guide 76 with respect to the stored sheet. FIGS. 2 and 3 show a state in which the auxiliary frame 34 is pushed into the main frame 32 most. In this state, since the first engagement pin 82 of the rear end guide 76 is located at a position closest to the front side of the first cam portion 86, the detection cam 104 is moved to the first cam surface near the front end. Abuts on the actuator 106, for example, the first and third operators of the switch 108 are turned on, and this information is output to a control unit provided in the image forming apparatus main body 12. It recognizes that a sheet of a predetermined size is stored in the sheet cassette 22.
In order to extend the auxiliary frame 34 from the main frame 32 from this state, a lock claw (not shown) is released from the engagement portion 74, the auxiliary frame 34 is pulled, and the lock claw is moved to the next engagement portion 74. Engage. At this time, the first gear 84, the second gear 94, and the sliding piece 98 move together with the auxiliary frame body 34 in a state as they are, and come to a state shown in FIG. That is, since the sliding piece 98 moves together with the auxiliary frame body 34, the sliding piece 98 comes into contact with the actuator 106 on the second cam surface of the detection cam 104, for example, only the first actuator of the switch 108 is turned on, and the corresponding sheet size Recognize.
Next, in order to store a small-sized sheet from this state, the lock of the rear end guide 76 is unlocked by the unlocking piece 80 of the rear end guide 76, and the rear end guide 76 is moved along the guide groove 78. Move. As a result, the second gear 84 rotates about the first support shaft 88 so that the first engagement pin 82 follows the first cam portion 86. Thereby, the second gear 88 rotates about the second support shaft 96. Then, by the rotation of the second gear 88, the sliding piece 98 slides via the rack portion 102 meshing with the second gear 88, and the other cam surface of the detection cam 104 comes into contact with the actuator 106, For example, only the second operator of the switch 108 is turned on, and the corresponding sheet size is recognized.
[0031]
As described above, according to the present invention, in the telescopic paper cassette, the auxiliary frame and the sheet size detecting means interlocking with the guide are provided. Even if the position of the guide is changed with the body pulled out, the sheet size can be reliably detected.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a front view of a sheet cassette used in the image forming apparatus according to the embodiment of the present invention.
FIG. 3 is a rear view of the sheet cassette used in the image forming apparatus according to the embodiment of the present disclosure.
FIG. 4 is a rear view showing a state in which an auxiliary frame is extended in a sheet cassette used in the image forming apparatus according to the embodiment of the present invention.
FIG. 5 is a rear view showing a state in which a rear end guide has been moved in a sheet cassette used in the image forming apparatus according to the embodiment of the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 10 image forming apparatus 12 image forming apparatus main body 14 image forming means 18 sheet feeding unit 22 sheet feeding cassette 32 main frame body 34 auxiliary frame body 76 rear end guide 84 first gear 86 first cam portion 90 second cam portion 94 second gear 98 sliding piece 102 rack 104 detection cam 106 actuator 108 switch

Claims (6)

A main frame, an auxiliary frame provided slidably with respect to the main frame, a guide slidably provided on the auxiliary frame, and connected to the auxiliary frame and the guide; Detecting means for detecting a position of the guide with respect to the main frame. 2. The sheet feeding cassette according to claim 1, wherein said detecting means has a detecting cam interlocked with said auxiliary frame and said guide, and a switch is operated by said detecting cam. 3. The sheet feeding cassette according to claim 2, wherein the detection cam includes a set of a plurality of cam surfaces having different shapes. The sheet cassette according to claim 2, wherein the switch has at least three identification units. The paper feed cassette according to any one of claims 2 to 4, wherein an actuator is interposed between the detection cam and the switch. The detecting means is formed with a first gear rotatably supported on the auxiliary frame body, the first gear being formed with a cam portion with which a pin provided on the guide slidably abuts, and meshing with the first gear. A second gear rotatably supported by the auxiliary frame, and a sliding piece provided with a rack portion meshing with the second gear and slidably supported by the auxiliary frame. The sheet feeding cassette according to any one of claims 1 to 5, further comprising: a detecting piece formed on the sliding piece.

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