JP2004043145A - Sheet feeder and image forming device provided with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet feeder and an image forming device provided with the same for securely detecting presence of a sheet with a simple structure. <P>SOLUTION: A detecting means 45 for detecting the presence of the sheet in a sheet housing means detects the presence of the sheet depending on a position of a lever member 46 moving to a position indicating that there is no sheet in the sheet housing means when the detecting means abuts on the sheet housed in the sheet housing means and there is no sheet in the sheet housing means. Then, the lever member 46 is energized to the sheet direction by an energizing means 48, and a moving speed of the lever member 46 in moving to the position indicating that there is no sheet in the sheet housing means is reduced by a braking means 48 also serving as the energizing means. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sheet feeding device and an image forming apparatus including the same, and more particularly, to a configuration of a detecting unit that detects the presence or absence of a sheet stored in a sheet storing unit.
[0002]
[Prior art]
2. Description of the Related Art In recent years, image forming apparatuses such as printers, copiers, and facsimile machines include a sheet feeding apparatus for separating sheets one by one and sending the sheets to an image forming unit. As such a sheet feeding apparatus, for example, a pickup roller can be moved up and down, and when feeding paper, the pickup roller is moved down to the sheet side to feed the sheet, and when not feeding paper, the pickup roller is raised. There is one that adopts a lift-up system that is separated from a seat by a lift.
[0003]
Here, in such a conventional sheet feeding apparatus of the lift-up type, when the sheet feeding cassette is mounted, the intermediate plate incorporated in the sheet feeding cassette is raised from the lowermost position by driving of the apparatus main body side. When the middle plate rises in this way, the pickup roller comes into contact with the uppermost sheet, and when the middle plate further rises, the pickup roller also rises.
[0004]
Thereafter, when the pickup roller rises to a predetermined position, the intermediate plate stops. In addition, the position where the middle plate stops is a position where an appropriate sheet feeding pressure is applied to the upper surface of the sheet by the pickup roller at the time of sheet feeding, and the sheet is reliably fed out by stopping the middle plate at such a position. Will be able to
[0005]
By the way, such a conventional sheet feeding apparatus is provided with a detecting unit for detecting the presence or absence of a sheet stored in the sheet storing unit, and the sheets are sequentially fed, and the sheet is stored in the sheet storing unit. When the sheet no longer exists, the detecting means detects this, and notifies the operator that the sheet is no longer present in the sheet storage means.
[0006]
FIG. 5 is a diagram showing a configuration of such a sheet presence detection device as a conventional detection unit for detecting the presence or absence of a sheet. In FIG. 5, reference numeral 41 denotes a sheet cassette provided as a sheet storage unit. An intermediate plate 50 is a sheet presence / absence detection device including an actuator 51 and a sensor (not shown). Reference numeral 41a denotes a slit formed in the middle plate 41, and the slit 41a is formed at a position facing the actuator 51.
[0007]
Here, when there is a sheet in the sheet cassette 4 (on the middle plate 41), the actuator 51 comes into contact with the sheet and stops at the position shown in FIG.
[0008]
On the other hand, when the sheet on the middle plate 41 runs out, the actuator 51 passes through the slit 41a of the middle plate 41 and descends to a position indicating that there is no sheet on the middle plate 41 shown in FIG. It has become. Here, when the actuator 51 descends to such a position, the sensor (not shown) is turned on. When the sensor is turned on in this way, the control unit (not shown) operates the sheet feeding cassette 4 (on the middle plate 41). It is determined that there is no sheet, and the operator is notified of the absence of the sheet by a buzzer, display, or the like.
[0009]
[Problems to be solved by the invention]
By the way, in the conventional sheet feeding apparatus provided with the sheet presence / absence detection device having such a configuration, in order to ensure the detection operation by the actuator 51, the actuator 51 is biased downward by a spring (not shown). I have. However, if the actuator 51 is urged downward by a spring as described above, when the sheet runs out and the actuator 51 descends to the position shown in FIG. 7B, the actuator 51 collides with, for example, the edge of the slit 41a. Become like
[0010]
Then, when colliding with the edge of the slit 41a in this manner, the actuator 51 rebounds upward due to the impact, and thereafter, an impact force for moving the actuator 51 upward, and a spring for moving the actuator 51 downward. Vibration in the vertical direction is caused by the urging force.
[0011]
Here, when the actuator 51 vibrates in this manner, the output of the sensor becomes unstable, and the control unit may start the sheet feeding operation even though there is no sheet on the middle plate 41. In this case, Causes a paper feed failure.
[0012]
The present invention has been made in view of such circumstances, and provides a sheet feeding apparatus capable of reliably detecting the presence or absence of a sheet with a simple configuration and an image forming apparatus including the sheet feeding apparatus. The purpose is.
[0013]
[Means for Solving the Problems]
According to the present invention, in a sheet feeding device configured to feed out a sheet stored in a sheet storage unit by a sheet feeding unit, the sheet abuts on a sheet stored in the sheet storage unit, and a sheet is stored in the sheet storage unit. When there is no, there is a lever member that moves to a position indicating that there is no sheet in the sheet storage unit, and a detection unit that detects the presence or absence of a sheet in the sheet storage unit according to the position of the lever member, Biasing means for biasing a lever member in the direction of the sheet; and brake means for reducing a moving speed when the lever member moves to a position indicating the absence of the sheet. Things.
[0014]
Further, the invention is characterized in that the brake means generates a frictional force with the lever member as the lever member moves.
[0015]
Further, the invention is characterized in that the brake means generates the frictional force by an elastic force.
[0016]
Further, the present invention is characterized in that the urging means and the brake means are integrated.
[0017]
Further, the present invention is characterized in that an urging means integrated with the brake means is arranged between the lever member and a frame of the detection means.
[0018]
Further, according to the present invention, in a sheet feeding apparatus configured to feed out a sheet stored in a sheet storing unit by a sheet feeding unit, the sheet is swingably attached to a shaft, and is attached to the sheet stored in the sheet storing unit. An actuator that abuts, and swings to a position indicating that there is no sheet in the sheet storage means when there is no sheet in the sheet storage means, and a sheet of the sheet storage means according to the swing position of the actuator. Detecting means for detecting the presence / absence, disposed on the shaft between a fixed member fixed to the shaft and the actuator, one end is engaged with the fixed member, and the other end is engaged with the actuator. A rotary urging force is applied to the actuator, and the actuator is arranged in a compressed state between the fixed member and the actuator. It is characterized in that and a torsion coil spring for generating a frictional force between the.
[0019]
According to another aspect of the invention, an image forming apparatus includes: an image forming unit that forms an image on a sheet; and the sheet feeding device according to any one of the above, which feeds a sheet to the image forming unit. Is what you do.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0021]
FIG. 1 is a diagram illustrating a schematic configuration of a laser beam printer as an example of an image forming apparatus including a sheet feeding device according to an embodiment of the present invention.
[0022]
In FIG. 1, reference numeral 1 denotes a laser beam printer. The laser beam printer 1 includes an image forming unit 2 for forming an image, a sheet feeding device 5 for separating and feeding sheets P to the image forming unit 2 one by one, and the like. It has.
[0023]
Here, the image forming unit 2 includes a process cartridge 7 and a transfer roller 9 that can be attached to and detached from a laser beam printer main body (hereinafter, referred to as an apparatus main body) 1A, and a sheet feeding device 5 has a sheet storage for stacking and storing sheets. The sheet feeding unit includes a sheet feeding cassette 4 serving as a unit, a pickup roller 6 serving as a sheet feeding unit, a feed roller 14, and a retard roller 15. The process cartridge 7 includes a photosensitive drum 8, a charging roller 20, a developing unit 22, a cleaning unit (not shown), and the like.
[0024]
The charging roller 20 is provided in contact with the photosensitive drum 8 so as to rotate following the photosensitive drum 8, and is used to uniformly charge the surface of the photosensitive drum when the photosensitive drum 8 rotates. The developing means 22 supplies toner to a developing area of the photosensitive drum 8 to develop a latent image formed on the photosensitive drum 8.
[0025]
Further, in the same figure, 12 is a laser scanner unit, 10 is a fixing unit, 13 is a paper discharge roller for discharging the sheet P to a sheet discharge stacking table 16, 1B is a cassette storage unit provided in the apparatus main body 1A, and 11 is a control unit. Department.
[0026]
Next, an image forming operation of the laser beam printer 1 configured as described above will be described.
[0027]
When image information is sent from a personal computer (not shown) or the like and a controller board (not shown) that has formed an image of the image information issues a print signal, the image data is loaded on a sheet cassette 4 detachably mounted on the apparatus main body 1A. The sheet P is fed one by one by a pickup roller 6 and a sheet separation feeding unit, and is fed to a nip between the photosensitive drum 8 and the transfer roller 9 in the process cartridge 7.
[0028]
On the other hand, a bit image (laser light) of the image information is radiated onto the photosensitive drum from the laser scanner unit 12 based on the image information together with the print command, and a latent image is formed on the surface of the photosensitive drum 8 according to the bit image. It is formed. Further, by developing this latent image, a toner image is formed on the photosensitive drum.
[0029]
Then, the toner image thus formed on the photosensitive drum is transferred to the sheet P sent to the nip between the photosensitive drum 8 and the transfer roller 9. Further, the sheet P to which the toner image has been transferred is sent to the fixing unit 10 and is heated and pressed by the fixing unit 10, whereby the toner image is fixed semi-permanently. Further, thereafter, the sheet P on which the toner image is fixed is discharged to the sheet discharge stacking table 16 by the discharge roller 13.
[0030]
In the figure, reference numeral 41 denotes a middle plate of the paper feed cassette 4, and the middle plate 41 is provided on the paper feed cassette 4 so as to be rotatable (movable) in the vertical direction with the locking portion 41a as a fulcrum. Reference numeral 42 denotes a side plate that is vertically provided at one end of a push-up plate 43 provided below the middle plate 41 and has a rack 42a formed at an upper end thereof. Reference numeral 44 denotes a motor (not shown) provided in the apparatus main body. The pinion is rotated by
[0031]
When the sheet cassette 4 is mounted in the cassette storage section 1B (see FIG. 1) provided in the apparatus main body 1A, the rack 42a of the side plate 42 meshes with the pinion 44. After that, the control unit 11 drives the motor to rotate the push-up plate 43 upward, thereby pushing up the middle plate 41 and causing the upper surface of the sheet P to have a substantially constant height at which an appropriate pressure is applied at the time of sheet feeding. I try to raise it.
[0032]
FIG. 2 shows the configuration of the sheet feeding device 5. In FIG. 2, reference numeral 45 denotes a sheet presence / absence detection device which is a detection unit for detecting the presence / absence of a sheet in the paper feed cassette 4. 3A to 3C are a side view, a front view, and a perspective view of the sheet presence detection device 45.
[0033]
Here, the sheet presence / absence detecting device 45 is disposed above the sheet feeding cassette 4 (the middle plate 41) as shown in FIG. 2, and an actuator 46 which is a lever member as shown in FIG. A sensor 47 is provided which detects the position of the actuator 46 by being turned on and off by a flag 46b provided on a shaft 46a of the actuator 46. In the present embodiment, an optical sensor having a light emitting unit and a light receiving unit (not shown) is used as the sensor 47.
[0034]
When there is a sheet on the middle plate 41, the actuator 46 comes into contact with the sheet and stops at the position shown in FIG. When the sheet is exhausted, it rotates downward, passes through the slit 41a of the middle plate 41, and descends to a position shown in FIG.
[0035]
Here, when the actuator 46 descends to such a position, the light is blocked by the flag 46b and the sensor 47 is turned on. Then, when the sensor 47 is turned on, the control unit 11 determines that there is no sheet in the sheet feeding cassette 4 (on the middle plate 41), and notifies the operator of the absence of the sheet by a buzzer, a display, or the like.
[0036]
As shown in FIG. 4, the actuator 46 has a torsion coil spring, one end of which is locked to a frame 45a as a fixing member of the detecting device 45 and the other end of which is locked to the upper surface of the actuator 46. 48 downwardly urged. Then, by urging the actuator 46 downward by the torsion coil spring 48 in this manner, the detection operation by the actuator 46 is ensured.
[0037]
By the way, in the present embodiment, the torsion coil spring 48 is compressed between the actuator 46 and the frame 45a of the sheet presence / absence detecting device 45 as shown in FIG. Attached to.
[0038]
Here, by disposing the torsion coil spring 48 in a compressed state between the actuator 46 and the frame 45a of the sheet presence / absence detecting device 45, when the actuator 46 descends, the torsion coil spring 48 and the actuator 46 A frictional force is generated therebetween. As a result, the speed at which the actuator 46 descends decreases.
[0039]
That is, by disposing the torsion coil spring 48 in a compressed state between the actuator 46 and the frame 45a of the detection device 45, the torsion coil spring 48 acts as a braking means, and the actuator 46 is at a position indicating that there is no seat. The moving speed when moving is reduced.
[0040]
When the speed of the lowering is reduced in this way, when the actuator 46 runs down to the position shown in FIG. 5B due to the absence of the sheet on the middle plate 41, the actuator 46 collides with the edge of the slit 41a. Shock is reduced, and as a result, vertical vibration of the actuator 46 is reduced.
[0041]
When the vibration of the actuator 46 is reduced in this manner, the output of the sensor 47 is stabilized, and the control unit 11 can reliably determine that there is no sheet on the middle plate 41. As a result, the feeding operation is not started even though there is no sheet on the middle plate 41, and as a result, the occurrence of feeding failure is eliminated.
[0042]
As described above, the actuator 46 is urged in the direction of the sheet by the spring 48, and the moving speed when the actuator 46 moves to the position indicating that there is no sheet is reduced by the torsion coil spring 48 also serving as a braking means. Vertical vibration of the actuator 46 can be prevented. This makes it possible to reliably detect the presence or absence of a sheet with a simple configuration, and to prevent the occurrence of a sheet feeding failure.
[0043]
Note that the present invention is not limited to the configuration of this embodiment. For example, in this embodiment, the urging means and the braking means are shared by a torsion coil spring, but the urging means and the braking means are combined. You may comprise with another member.
[0044]
【The invention's effect】
As described above, according to the present invention, the urging means presses the lever member which comes into contact with the sheet stored in the sheet storage means and moves to a position indicating that there is no sheet when the sheet storage means has no sheet. By urging in the direction of the sheet, and by reducing the moving speed when the lever member moves to a position indicating that there is no sheet in the sheet storage means by the brake means, the presence or absence of the sheet can be reliably determined with a simple configuration. Can be detected.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a schematic configuration of a laser beam printer as an example of an image forming apparatus including a sheet feeding device according to an embodiment of the present invention.
FIG. 2 is a perspective view of a main part for describing a configuration of a sheet feeding device of the laser beam printer.
FIG. 3 is a diagram illustrating a configuration of a sheet presence / absence detection device provided in the sheet feeding device.
FIG. 4 is a partial cross-sectional side view of the sheet presence / absence detection device.
FIG. 5 is a diagram illustrating a configuration of a sheet presence detection device that is a conventional detection unit that detects the presence or absence of a sheet.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 laser beam printer 2 image forming unit 4 paper feed cassette 5 sheet feeding device 41 middle plate 45 sheet presence detection device 46 actuator 47 sensor 45a frame 48 torsion coil spring

Claims (7)

In a sheet feeding apparatus configured to send out a sheet stored in a sheet storing unit by a sheet feeding unit,
A lever member that contacts a sheet stored in the sheet storage unit and moves to a position indicating that there is no sheet in the sheet storage unit when there is no sheet in the sheet storage unit; Detection means for detecting the presence or absence of a sheet in the sheet storage means according to the position of
Urging means for urging the lever member in the direction of the sheet;
Brake means for reducing the moving speed when the lever member moves to a position indicating that the seat is absent,
A sheet feeding device comprising: 2. The sheet feeding device according to claim 1, wherein the brake means generates a frictional force between the lever member and the lever member as the lever member moves. 3. The sheet feeding device according to claim 2, wherein the brake unit generates the frictional force by an elastic force. The sheet feeding device according to any one of claims 1 to 3, wherein the urging unit and the brake unit are integrated. 5. The sheet feeding device according to claim 4, wherein a biasing unit integrated with the brake unit is disposed between the lever member and a frame of the detection unit. In a sheet feeding apparatus configured to send out a sheet stored in a sheet storing unit by a sheet feeding unit,
Swingably attached to a shaft, abutting against a sheet stored in the sheet storage means, and swinging to a position indicating that there is no sheet in the sheet storage means when there is no sheet in the sheet storage means; Actuator to
Detecting means for detecting the presence or absence of a sheet in the sheet storage means according to a swing position of the actuator;
The actuator is disposed on the shaft between a fixed member fixed to the shaft and the actuator, and one end is engaged with the fixed member, and the other end is engaged with the actuator to apply a rotational urging force to the actuator, A torsion coil spring for generating a frictional force between the fixing member and the actuator by being arranged in a compressed state between the fixing member and the actuator,
A sheet feeding device comprising: An image forming apparatus comprising: an image forming unit that forms an image on a sheet; and the sheet feeding apparatus according to claim 1 that feeds the sheet to the image forming unit. apparatus.

Images