JP3915908B2 - Paper cassette - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a paper feed cassette, for example, a paper feed cassette used in an image forming apparatus.
[0002]
[Prior art]
As a paper feed cassette for an image forming apparatus, it is known to have a main frame and an auxiliary frame that is slidably provided on the main frame, and to expand and contract the auxiliary frame according to the size of the sheet to be stored. It is. Further, the rear end guide is slidably provided on the auxiliary frame body, and the rear end guide is slid in accordance with the sheet size in a state where the auxiliary frame body is pushed most into the main frame body. Also known are those adapted to accommodate the sheet size. Furthermore, it is also known to detect the sheet size in this type of telescopic cassette (see Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-139572
[Problems to be solved by the invention]
In the above conventional example, it is most preferable to slide the rear end guide according to the sheet size in a state where the auxiliary frame body is pushed most into the main frame body and pull out the auxiliary frame body with respect to the main frame body. It is assumed that a large sheet size sheet that cannot be accommodated in the pushed-in state is accommodated. Therefore, the sheet detection is performed separately by the first detection unit that detects the position of the rear end guide with respect to the main frame and the second detection unit that detects the position of the auxiliary frame with respect to the main frame. It is.
However, it is conceivable to increase the degree of freedom corresponding to the sheet size by sliding the rear end guide with respect to the auxiliary frame even when the auxiliary frame is pulled out of the main frame. In such a case, the conventional example has a problem in that the sheet size cannot be detected because the first detection unit and the second detection unit are not linked.
[0005]
The present invention relates to a telescopic paper feed cassette that can reliably detect the sheet size even when the position of the guide is changed while the auxiliary frame is pulled out from the main frame. The purpose is to provide.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is characterized by a main frame, an auxiliary frame provided slidably with respect to the main frame, and the auxiliary frame formed in the main frame. A guide that is slidably provided on the auxiliary frame body in the most pushed state and extended state, a cam portion that is rotated according to the sliding of the guide and is formed in a groove shape, and the auxiliary A sliding piece is provided that is slidable with respect to the frame body, and is slid with respect to the auxiliary frame body when the cam portion is moved, and a detection cam is formed, the auxiliary frame body being the main frame Detecting means for detecting a position of the guide with respect to the main frame body in a state of being most pushed into the body and in a stretched state, and the auxiliary frame body is stretched from a state of being pushed most into the main frame body In this case, the cam portion and the sliding piece of the detecting means remain in the state as they are. In the paper feed cassette move together. Therefore, the position of the guide relative to the main frame, that is, the sheet size can be detected even when the auxiliary frame is pulled out from the main frame.
[0007]
Detection means, it is preferable to actuate the switch by the detection cam. Thus, by making the detection cam interlock with the auxiliary frame and the guide, the sheet size can be detected with one switch.
[0008]
Further, it is preferable that the detection cam is constituted by a set of cam surfaces having a plurality of different shapes. Thereby, the position of the detection cam can be easily detected. It is further preferable to combine a detection cam having a plurality of cam surfaces having different shapes with a switch having at least three identification means. If the switch has, for example, three identification means, eight sheet sizes can be detected by combining the identification means.
[0009]
Moreover, 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 feed cassette, it is possible to change the arrangement of the switches on the paper feed unit main body side by selecting the actuator length as appropriate. It can correspond to.
[0010]
Further, the detection means includes a first gear formed with a cam portion on which a pin provided on the guide is slidably contacted, and rotatably supported on the auxiliary frame, and the first gear. And a second piece of gear that is rotatably supported by the auxiliary frame, and a rack that meshes with the second gear and is slidably supported by the auxiliary frame. It is preferable that the detection cam is provided on the sliding piece. By configuring the gear in this way, the position of the guide movement can be detected at least accurately.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will 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 includes 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 in an upper portion of the image forming apparatus main body 12. In addition, for example, two-stage sheet feeding units 18 and 18 are disposed below the image forming apparatus main body 12. Further, below the image forming apparatus main body 12, two-stage sheet feeding units 18, 18 that are detachably mounted as options are arranged.
[0012]
Each paper feed unit 18 has a paper feed unit main body 20 and a paper feed cassette 22 in which paper is stored. The paper feed cassette 22 is slidably attached to the paper feed unit main body 20 and is pulled out in the front direction (right direction in FIG. 1). In addition, a nudger roll 24 is disposed in the upper portion near the back 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 feeding units 18 and 18 are provided with a pair of feed rolls 30 respectively.
[0013]
At least one of the plurality of paper feed cassettes 22 is extendable and includes a main frame 32 and an auxiliary frame 34 slidably provided with respect to the main frame 32. 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 a length A that is at least a part of the auxiliary frame 34 and is contracted. In such a manner, the image forming apparatus main body 12 coincides with the front wall surface. The sheet cassette 22 will be described in detail later.
[0014]
The conveyance path 36 is a sheet path from the nudger roll 24 to the discharge port 38 of the lowermost sheet feeding unit 18d, and this conveyance path 36 is near the back surface (the left side surface in FIG. 1) of the image forming apparatus main body 12. In addition, it has a portion that is formed substantially vertically from the feeding roll 30 of the lowermost sheet feeding unit 18 to the fixing device 62 described later. A transfer device 56 and an image carrier 54 which will be described later are disposed on the upstream side of the fixing device 64 in the conveyance path 36, and a resist roll 40 is disposed on the upstream side of the transfer device 62 and the image carrier 54. Further, a discharge roll 42 is disposed in the vicinity of the discharge port 38 of the conveyance path 36.
[0015]
Therefore, the sheet transported from the paper feeding unit 18 is temporarily stopped by the registration roll 40 in the transport path 36, sent to the image forming means 14 at a predetermined timing, and an image is formed. 16 is discharged.
[0016]
However, in the case of duplex printing, it is returned to the reverse path. That is, the front of the discharge roll 42 is divided into two forks, and a switching claw 44 is provided at the divided portion, and an inversion path 46 is formed to return from the divided portion to the registration roll 42. The reversing path 46 is provided with conveying rolls 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 in front of the trailing edge of the sheet. Thus, the discharge roll 42 is reversed, the recording medium is guided to the reverse 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.
[0017]
The discharge unit 16 includes an inclined unit 50 that is rotatable with respect to the image forming apparatus main body 12. The inclined portion 50 has a lower discharge port portion and is inclined so as to gradually increase in the front direction (right direction in FIG. 1), with the discharge port portion as a lower end and a higher tip as an upper end. The inclined portion 50 is supported by the image forming apparatus main body 12 so as to be rotatable around the lower end. As shown by a two-dot chain line in FIG. 1, when the inclined portion 50 is rotated upward and opened, an opening portion 52 is formed, and a process cartridge 66 described later can be attached and detached through the opening portion 52. .
[0018]
The image forming means 14 is of, for example, an electrophotographic system, and includes an image carrier 54 made of a photosensitive member, a charging device 56 made of, for example, a charging roll that uniformly charges the image carrier 54, and charging by the charging device 56. An optical writing device 58 that writes a latent image on the image carrier 54 by light, a developing device 60 that visualizes the latent image of the image carrier 54 formed by the optical writing device 58 with a developer, and the developing device. A transfer device 62 composed of, for example, a transfer roll for transferring the developer image by the sheet 60 to the paper, a cleaning device 63 composed of, for example, a blade for cleaning the developer remaining on the image carrier 54, and the paper transferred by the transfer device 62 For example, a fixing device 64 composed of a pressure roll and a heating roll. The optical writing device 58 is composed of, for example, a scanning type laser exposure device, and is arranged in the vicinity of the front surface of the image forming apparatus main body 12 in parallel with the paper feeding unit 18 described above, and exposes the image carrier 54 across the developing device 60. . Further, the developing device 60 includes a developing roll 66 that faces the image carrier 54.
[0019]
The process cartridge 68 is obtained by integrating 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 attached and detached through the opening portion 52 formed when the inclined portion 50 is opened as described above.
[0020]
An example of the paper feed cassette 22 is shown in FIGS. The main frame 32 supports the above-described retard roll 26 on the back side in the insertion direction of the paper feed cassette 22. The main frame 32 is provided with a sheet stacking plate 70 on which the sheets are stacked so as to be movable up and down. The sheet stacking plate 70 is raised according to the remaining amount of sheets. The auxiliary frame body 34 is slidably inserted into the side surface portion of the main frame body 32 at the side surface portion of the auxiliary frame body 34. A lock groove 72 is formed in the auxiliary frame 34 in the front-rear direction, and for example, three engagement portions 74 are formed in the lock groove 72, and the main frame 32 is slidable in the engagement portion 74. A locking claw (not shown) provided on the engaging portion engages, and the auxiliary frame 34 is extended and fixed in, for example, three stages.
[0021]
Further, a rear end guide 76 for guiding the rear end of the sheet is disposed in the auxiliary frame body 34. The rear end guide 76 engages with a guide groove 78 formed in the auxiliary frame body 34, and It is erected so that it can move forward and backward. The rear end guide 76 is provided with, for example, two lock release pieces 80, and the lock of the rear end guide 76 is released by sliding the lock release piece 80 inward against an elastic body (not shown). The rear end guide 76 can be moved along the guide groove 78. The rear end guide 76 is formed with a first engagement pin 82 projecting, the engagement pin 82 projects to the back side of the auxiliary frame 34, and a first cam portion 86 formed on the first gear 84. Is engaged.
[0022]
The first gear 84 is composed of a large spur gear, for example, and is rotatably supported by a first support shaft 88 provided on the auxiliary frame 34. The first gear 84 is formed 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 is scaled and rotated according to the reciprocation of the rear end guide 76. The second cam portion 90 is engaged with a second engagement pin 92 that is formed to protrude from the auxiliary frame 34, so that the first gear 84 rotates reliably around the first support shaft 88. In addition, the rotation range of the first gear 84 is restricted.
[0023]
An arc-shaped tooth centered on the first support shaft 88 is formed at the end of the first gear 84, and the second gear 94 meshes with the tooth. The second gear 94 is an idle gear, and rotates around a second support shaft 96 that is formed to protrude from the auxiliary frame 34. The rack portion 102 of the sliding piece 98 is engaged with the second gear 94.
[0024]
The sliding piece 98 is supported by a third engagement pin 100 protruding from the auxiliary frame body 34 so as to be slidable with respect to the auxiliary frame body 34, and the rack portion 102 is provided on one surface of the sliding piece 98. Is formed and meshed 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 includes a plurality of cam surfaces (four in this embodiment) each having a different shape. For example, an actuator 106 is provided on the main frame 32 so as to face the detection cam 104. The actuator 106 is composed of, for example, three plate-like bodies, and protrudes to the side surface of the main frame 32 when the cam surface of the detection cam 106 abuts. Opposite to the actuator 106, a switch 108 is provided in the paper feeding unit main body 20 (FIG. 1). The switch 106 is a microswitch having, for example, three actuators that are turned on and off, and constitutes three identification means. Thus, 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.
[0025]
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 of the image carrier 54 formed by the optical writing device 58 is visualized by the developer of the developing device 60.
[0026]
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 fed out by a nudger roll 24 and are rolled by a retard roll 26 and a feed roll 28 to be registered rolls 40 and is temporarily stopped by the resist roll 40 and is guided between the transfer device 62 and the image carrier 54 with timing.
[0027]
When the recording medium is guided between the transfer device 62 and the image carrier 54 in this way, 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 passes through the fixing device 64 and is discharged to the discharge unit 16.
[0028]
In the paper feed cassette 22, the size of the stored sheet is detected. The rear end of the sheet is in contact with the rear end guide 76 with respect to the stored sheet. The state where the auxiliary frame 34 is pushed most into the main frame 32 is shown in FIGS. In this state, since the first engagement pin 82 of the rear end guide 76 is in a position closest to the front side of the first cam portion 86, the detection cam 104 is the first cam surface near the front end. Comes into contact with the actuator 106, for example, the first actuator and the third actuator of the switch 108 are turned on, and this information is output to the control unit provided in the image forming apparatus main body 12, and in this control unit, It recognizes that a sheet of a predetermined size is stored in the paper feed cassette 22.
[0029]
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 engaging portion 74, the auxiliary frame 34 is pulled, and the lock claw is engaged with the next engaging portion 74. . At this time, the first gear 84, the second gear 94, and the sliding piece 98 move together with the auxiliary frame 34 as they are, and the state shown in FIG. 4 is obtained. That is, since the sliding piece 98 moves together with the auxiliary frame 34, the actuator 106 is brought into contact with the second cam surface of the detection cam 104, and for example, only the first actuator of the switch 108 is turned on. Recognize
[0030]
Next, in order to store a small sheet from this state, the rear end guide 76 is unlocked by the lock release piece 80 of the rear end guide 76, and the rear end guide 76 is moved along the guide groove 78. . 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. As a result, 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 through the rack portion 102 that meshes 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 actuator of the switch switch 108 is turned on to recognize the corresponding sheet size.
[0031]
【The invention's effect】
As described above, according to the present invention, the retractable sheet cassette is provided with the sheet size detecting means interlocking with the auxiliary frame and the guide, so that the auxiliary frame is pulled out from the main frame. Even if the position of the guide is changed, 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 paper feed cassette used in the image forming apparatus according to the embodiment of the present invention.
FIG. 3 is a rear view of a paper feed cassette used in the image forming apparatus according to the embodiment of the present invention.
FIG. 4 is a rear view showing a state in which an auxiliary frame is extended in a paper feed 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 is moved in the paper feed cassette used in the image forming apparatus according to the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Image forming apparatus main body 14 Image forming means 18 Paper feed unit 22 Paper feed cassette 32 Main frame body 34 Auxiliary frame body 76 Rear end guide 84 First gear 86 First cam part 90 Second cam part 94 Second gear 98 Sliding piece 102 Rack portion 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 provided slidably on the auxiliary frame in a state where the auxiliary frame is most pushed into the main frame and in a stretched state ;
A cam portion that is rotated according to the sliding of the guide and is formed so as to be slidable with respect to the auxiliary frame body, and when the cam portion is moved, Detecting means for detecting a position of the guide with respect to the main frame body in a state where the auxiliary frame body is pushed into the main frame body and in a stretched state. When,
Have
When the auxiliary frame is extended from a state where the auxiliary frame is pushed most into the main frame, the cam portion and the sliding piece of the detection means move together with the auxiliary frame in the same state. Paper cassette. 2. A sheet feeding cassette according to claim 1 , wherein said detecting means operates a switch by said detecting cam. 3. The paper feed cassette according to claim 2, wherein the detection cam is composed of a set of cam surfaces having a plurality of different shapes. 4. The paper feed cassette according to claim 2, wherein the switch has at least three identification means. 5. The paper feed cassette according to claim 2, wherein an actuator is interposed between the detection cam and the switch. The detecting means is formed with a cam portion on which a pin provided on the guide is slidably contacted, and meshed with the first gear supported rotatably on the auxiliary frame. And a second gear rotatably supported by the auxiliary frame, and a slide piece provided with a rack portion meshing with the second gear and slidably supported by the auxiliary frame. 6. The paper feed cassette according to claim 1, wherein the slide cam is provided with the detection cam.

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