JP6344294B2 - Sheet feeding device and image forming apparatus having sheet feeding device - Google Patents

Description

  The present invention relates to a sheet feeding device and an image forming apparatus including the sheet feeding device, and more particularly to a technique for detecting a sheet stored in a sheet feeding cassette.

  In image forming apparatuses such as copiers, printers, facsimile machines, and multifunction machines, images are formed according to the size of the paper to be fed. Therefore, the size of the paper stored in the paper cassette is detected correctly. It is necessary to keep it. For example, Patent Document 1 discloses a technique for providing a plurality of detection switches at the bottom of a paper feed cassette and detecting the size of the paper stored in the paper feed cassette based on a detection signal output from the detection switch. ing.

JP 2003-81446 A

  However, in the case where a plurality of sizes of paper are mixed in the paper bundle accommodated in the paper feed cassette, the size of the paper accommodated in the paper feed cassette can be obtained even if the technique described in Patent Document 1 is used. Cannot be detected correctly. For this reason, the image forming apparatus cannot form an image correctly.

  Further, the image forming apparatus cannot correctly form an image even when the paper stored in the paper feed cassette is bent. For this reason, even if the technique described in Patent Document 1 is used, it is not possible to detect such bending of the paper.

  In other words, the technique described in the above-mentioned Patent Document 1 cannot detect the presence or absence of inappropriate paper that affects the quality of image formation. The present invention has been made in view of the above-described circumstances, and an object thereof is to make it possible to detect an inappropriate sheet included in a sheet bundle accommodated in a sheet feeding cassette.

A sheet feeding device according to one aspect of the present invention is provided above a sheet feeding cassette, a roller that feeds sheets one by one from a sheet bundle accommodated in the sheet feeding cassette, Two ultrasonic sensors that oscillate sound waves toward the upper surface of the sheet bundle, receive ultrasonic waves reflected by the upper surface of the sheet bundle, and output an output signal corresponding to the received ultrasonic waves; Of the two ultrasonic sensors, one ultrasonic sensor is moved along a first path provided above the paper cassette, and the other ultrasonic sensor is a second sensor provided above the paper cassette. A moving mechanism that moves along a path, and an output signal output from the two ultrasonic sensors while the moving mechanism moves the two ultrasonic sensors. Presence or absence A determination unit that, if the previous SL determination unit determines that there is improper paper, a sheet feeding apparatus and an operation control unit which performs control to stop the feeding operation by the roller.

  An image forming apparatus according to another aspect of the present invention is an image forming apparatus that includes the paper feeding device and an image forming unit that forms an image on paper fed from the paper feeding device. is there.

  According to the present invention, it is possible to detect inappropriate paper contained in a paper bundle stored in a paper feed cassette.

1 is a cross-sectional view illustrating a structure of an image forming apparatus according to an embodiment of the present invention. 1 is a functional block diagram illustrating a main internal configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a perspective view illustrating a structure of a sheet feeding unit of an image forming apparatus according to an embodiment of the present invention. 1 is a cross-sectional view illustrating a structure of a paper feed unit of an image forming apparatus according to an embodiment of the present invention. FIGS. 4A and 4B are top views showing the structure of a sheet feeding unit of an image forming apparatus according to an embodiment of the present disclosure. FIGS. 4A and 4B are diagrams illustrating an example of a sheet bundle stored in a sheet feeding cassette of an image forming apparatus according to an embodiment of the present disclosure. 6A is a graph showing an output value of an output signal output from the sensor when the sheet bundle shown in FIG. 6A is stored in the paper feed cassette, and FIG. 7 is a graph showing an output value of an output signal output from a sensor when the sheet bundle shown in B) is stored in a sheet feeding cassette. FIGS. 6A and 6B are diagrams illustrating another example of a sheet bundle stored in a sheet feeding cassette of the image forming apparatus according to the embodiment of the present disclosure. 3 is a flowchart showing a flow of operations of the image forming apparatus according to the embodiment of the present invention. FIG. 6 is a diagram illustrating an example of a notification screen displayed on a display unit of the image forming apparatus according to the embodiment of the present invention. 10 is a flowchart showing a flow of operations of the image forming apparatus according to Modification 1. FIGS. 7A and 7B are cross-sectional views illustrating the structure of a sheet feeding unit of an image forming apparatus according to a second modification.

  Hereinafter, a sheet feeding device according to an embodiment of the present invention and an image forming apparatus including the sheet feeding device will be described with reference to the drawings.

  FIG. 1 is a sectional view showing the structure of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 is a multifunction machine having a plurality of functions such as a copy function, a printer function, a scanner function, and a facsimile function. The image forming apparatus 1 includes a document reading unit 5, a document feeding unit 6, an image forming unit 12, a fixing unit 13, and a sheet feeding unit 14 in the apparatus main body 11.

  When the image forming apparatus 1 performs a document reading operation, the document reading unit 5 optically reads a document fed by the document feeding unit 6 or a document placed on the document placing glass 161, Generate image data.

  When the image forming apparatus 1 performs an image forming operation, the image forming unit 12 feeds paper from the paper feeding unit 14 based on image data generated by a document reading operation, image data received from a network-connected computer, or the like. A toner image is formed on a sheet P as a recording medium.

  The image forming units 12M, 12C, 12Y, and 12Bk of the image forming unit 12 include a photosensitive drum 121, a developing device 122, a charging device 123, an exposure device 124, and a primary transfer roller 126, respectively. A toner image is formed on the photosensitive drum 121 by a development process. The toner image is transferred by the primary transfer roller 126 onto the intermediate transfer belt 125 stretched around the driving roller 125A and the driven roller 125B.

  The toner images of the respective colors transferred onto the intermediate transfer belt 125 are superimposed on the intermediate transfer belt 125 with the transfer timing adjusted to form a color toner image. The secondary transfer roller 210 conveys the color toner image formed on the surface of the intermediate transfer belt 125 from the sheet feeding unit 14 through the conveyance path 190 at the nip N between the intermediate transfer belt 125 and the driving roller 125A. It is transferred to the paper P that has been transferred. Thereafter, the fixing unit 13 fixes the toner image on the paper P to the paper P by thermocompression bonding. The paper P on which the color image has been formed after the fixing process is completed is discharged to a discharge tray.

  Next, the internal configuration of the image forming apparatus 1 will be described. FIG. 2 is a functional block diagram showing the main internal configuration of the image forming apparatus 1.

  The image forming apparatus 1 includes an image memory 32, an operation unit 47, and a storage unit 92 in addition to the document reading unit 5, the document feeding unit 6, the image forming unit 12, the fixing unit 13, and the paper feeding unit 14 described above. And a control unit 10 or the like.

  The image memory 32 is an area for temporarily storing image data obtained by reading by the document reading unit 5 and image data to be image formed by the image forming unit 12.

  The operation unit 47 includes a touch panel unit that receives instructions from the user for various operations and processes that can be executed by the image forming apparatus 1, physical keys, and the like. The touch panel unit includes a display unit 473 such as an LCD (Liquid Crystal Display) provided with a touch panel.

  The storage unit 92 is a large-capacity storage device such as an HDD (Hard Disk Drive).

  The control unit 10 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), and the like. The control unit 10 functions as the operation control unit 100, the sensor control unit 101, the determination unit 102, and the notification control unit 103 by executing the control program stored in the ROM or the storage unit 92 on the CPU. To do. Note that the operation control unit 100, the sensor control unit 101, the determination unit 102, and the notification control unit 103 of the control unit 10 may each be configured by a hard circuit, regardless of the operation based on the control program.

  The operation control unit 100 is connected to the document reading unit 5, the document feeding unit 6, the image forming unit 12, the paper feeding unit 14, the image memory 32, the operation unit 47, the storage unit 92, and the like. Operation control of each of the above mechanisms and transmission / reception of signals or data to / from each mechanism are performed. In particular, the operation control unit 100 has a function of controlling the sheet feeding operation by the sheet feeding unit 14.

  The sensor control unit 101 has a function of controlling a moving operation of a first sensor 145 and a second sensor 146 described later installed in the paper feeding unit 14.

  Based on the output signals output from the first sensor 145 and the second sensor 146, the determination unit 102 applies inappropriate paper that affects the quality of image formation by the image forming unit 12 to the paper bundle in the paper feeding unit 14. It has a function of determining whether or not it is included.

  The notification control unit 103 (notification unit) has a function of executing a predetermined warning notification process when the determination unit 102 determines that an inappropriate sheet is included.

  A sheet feeding device according to an embodiment of the present invention includes the sheet feeding unit 14 and the control unit 10 described above. Hereinafter, a detailed configuration of the paper feeding device will be described. In this specification, a description will be given by taking, as an example, the sheet feeding device positioned at the bottom of the plurality of sheet feeding devices provided in the image forming apparatus 1.

  FIG. 3 is a perspective view showing the structure of the paper feed unit 14. FIG. 4 is a cross-sectional view showing the structure of the paper feeding unit 14. As shown in FIGS. 3 and 4, the paper feed unit 14 includes a paper feed cassette 15 that constitutes an outline of the paper feed unit 14, and accommodates the paper bundle P <b> 1 therein. The paper feed cassette 15 is configured to be detachable from the apparatus main body 11. In the example shown in FIGS. 1, 3, and 4, the paper feed cassette 15 can be pulled out to the right side (minus X direction side) of the drawing.

  The paper feed unit 14 includes a pickup roller 141 and a transport roller 171. The pickup roller 141 is configured to be movable up and down by a lift drive unit 142 (see FIG. 2) including a motor, a gear, a driver, and the like. When the pickup roller 141 is lowered by the lift drive unit 142, the peripheral surface of the pickup roller 141 comes into contact with the uppermost surface of the sheet bundle P <b> 1 accommodated in the sheet feeding cassette 15. In this state, the pickup roller 141 rotates to feed the sheets one by one from the sheet bundle P1. The sheet fed by the pickup roller 141 is transported toward the image forming unit 12 by the transport roller 171.

  Further, in order to position the sheet bundle P1, the sheet feeding unit 14 includes a left end regulating member 153A, a right end regulating member 153B, and a rear end regulating member 155 on the placement surface 151 on which the sheet bundle P1 is placed. is set up. The left end regulating member 153A and the right end regulating member 153B are slidable in the Z direction and the minus Z direction along the groove 154 formed on the placement surface 151. The rear end regulating member 155 is slidable in the X direction and the minus X direction along the groove 156 formed on the placement surface 151. After the sheet bundle P1 is stored in the sheet feeding cassette 15 by the user, the left end regulating member 153A, the right end regulating member 153B, and the rear end regulating member 155 are slid and moved so as to contact the sheet bundle P1. The positioning of the bundle P1 is completed. In order to detect the positions of the left end regulating member 153A, the right end regulating member 153B, and the rear end regulating member 155, the sheet feeding unit 14 is provided with a regulated position detecting unit 143 (see FIG. 2) including a plurality of sensors. It has been. Based on the output signal output from the restriction position detection unit 143, the operation control unit 100 of the control unit 10 specifies the sheet size of the sheet bundle P1.

  Here, above the paper feed cassette 15 (Y direction side), a first sensor 145 and a second sensor 146 (see FIG. 2) serve as a paper height detector 144 (see FIG. 2) that detects the height of the sheet bundle P1. 5). Each of the first sensor 145 and the second sensor 146 is an ultrasonic sensor using a piezoelectric element, and its main oscillation direction and main reception direction are directed downward (minus Y direction). The first sensor 145 and the second sensor 146 oscillate ultrasonic waves by applying a voltage having a predetermined voltage value to the piezoelectric element. The oscillated ultrasonic wave is reflected by the upper surface of the sheet bundle P1, and then received by the first sensor 145 and the second sensor 146. An electromotive force corresponding to the intensity of the received ultrasonic wave is generated in the piezoelectric element. As a result, the first sensor 145 and the second sensor 146 output an output signal corresponding to the intensity of the received ultrasonic wave.

  Based on the output signals output from the first sensor 145 and the second sensor 146, the determination unit 102 (see FIG. 2) of the control unit 10 extends from the upper surface of the sheet bundle P1 to the first sensor 145 and the second sensor 146. Identify the distance. In other words, the determination unit 102 specifies the height from the placement surface 151 of the paper feed cassette 15 to the upper surface of the sheet bundle P1. As described above, an ultrasonic sensor using a piezoelectric element generally has higher sensitivity than an optical sensor using a photodiode. For this reason, the determination unit 102 can accurately specify the height from the placement surface 151 of the paper feed cassette 15 to the upper surface of the sheet bundle P1.

  The first sensor 145 and the second sensor 146 are rails provided above the paper cassette 15 (Y direction side) by a sensor driving unit 147 (see FIG. 2) including a motor, a gear, a driver, and the like. It reciprocates on the part 16. FIGS. 5A and 5B are top views showing the structure of the paper supply unit 14. As shown in FIGS. 5A and 5B, the rail portion 16 is composed of two linear rails 161 and 162. The rails 161 and 162 intersect at a predetermined position E above the paper feed cassette 15 (Y direction side).

  The first sensor 145 moves from a position A that is one end of the rail 161 to a position C that is the other end of the rail 161 in a state in which a not-shown insertion portion is fitted in the groove of the rail 161 ( (See arrows in FIGS. 5A and 5B). Similarly, the second sensor 146 has a position between a position B which is one end of the rail 162 and a position D which is the other end of the rail 162 in a state where a not-shown insertion portion is fitted in the groove of the rail 162. Move (see arrows in FIGS. 5A and 5B).

  The determination unit 102 of the control unit 10 forms an image based on output signals output from the first sensor 145 and the second sensor 146 while the sensor driving unit 147 moves the first sensor 145 and the second sensor 146. It is determined whether or not an inappropriate sheet that affects the quality of image formation by the unit 12 is included in the sheet bundle P1. Specifically, based on the output signals output from the first sensor 145 and the second sensor 146, the determination unit 102 determines the upper surface of the sheet bundle P1 located below the rail 161 and the rail 162 (minus Y direction side). The presence or absence of a step is determined. The determination unit 102 determines that there is an inappropriate sheet when determining that there is a step, and determines that there is no inappropriate sheet when determining that there is no step.

  FIGS. 6A and 6B are diagrams illustrating an example of a sheet bundle stored in the sheet feeding cassette 15. FIG. 7A is a graph showing the output value of the output signal output from the first sensor 145 when the sheet bundle shown in FIG. FIG. 7B is a graph showing the output value of the output signal output from the first sensor 145 when the sheet bundle shown in FIG.

  In the example shown in FIG. 6A, a sheet bundle made up of A4 size sheets is stored in the sheet feeding cassette 15, and the uppermost sheet of the sheet bundle is A4 size sheet P2. In this case, the first sensor 145 outputs an output signal having an output value shown in FIG. That is, while the first sensor 145 is moved from the position A to the position C, the output value of the output signal output from the first sensor 145 is constant. In this case, the determination unit 102 determines that there is no step on the upper surface of the sheet bundle located below the rail 161 (minus Y direction side), and there is an inappropriate sheet in the sheet bundle stored in the sheet feeding cassette 15. Judge that there is no. Even when the output value of the output signal varies, if the variation value is equal to or less than a predetermined value, the determination unit 102 determines that the variation in the output value is an error and supplies it. It is determined that there is no inappropriate paper in the paper bundle stored in the paper cassette 15.

  On the other hand, in the example shown in FIG. 6B, a sheet of A5 size is mixed in a sheet bundle of A4 size sheets, and the uppermost sheet of the sheet bundle is A5 size sheet P3. Yes. In this case, the first sensor 145 outputs an output signal having an output value shown in FIG. That is, when the first sensor 145 passes through the position E, the output value of the output signal output from the first sensor 145 varies. When the fluctuation value of the output value is larger than a predetermined value, the determination unit 102 determines that the fluctuation of the output value is a step existing on the upper surface of the sheet bundle, and is stored in the paper feed cassette 15. It is determined that there is inappropriate paper in the paper bundle.

  FIG. 8A and FIG. 8B are diagrams illustrating another example of the sheet bundle accommodated in the sheet feeding cassette 15. In the example shown in FIG. 8A, one sheet smaller than the A5 size is mixed in a sheet bundle made up of A4 size sheets, and the uppermost sheet of the sheet bundle is the small sheet P4. In this case, for the second sensor 146, the output value of the output signal is constant, but for the first sensor 145, the output value of the output signal varies when passing the position F. For this reason, the determination unit 102 can determine that there is an inappropriate sheet in the sheet bundle stored in the sheet feeding cassette 15.

  In the example shown in FIG. 8B, a part of the uppermost sheet P5 of the sheet bundle is bent. In this case, for the first sensor 145, the output value of the output signal is constant, but for the second sensor 146, the output value of the output signal varies when passing through the position G and the position H. For this reason, the determination unit 102 can determine that there is an inappropriate sheet in the sheet bundle stored in the sheet feeding cassette 15.

  As described above, as a configuration for detecting the height of the sheet bundle, two ultrasonic sensors, the first sensor 145 and the second sensor 146, are provided, and further, the first path and the first path which are the movement paths of the first sensor 145 are provided. A configuration in which only one ultrasonic sensor is provided by crossing the second path, which is the movement path of the two sensors 146, above the paper feed cassette 15 (Y direction side) Compared with a general configuration in which a plurality of detection switches are provided at the bottom, it is possible to detect the presence or absence of a step in a wide range on the upper surface of the sheet bundle, so that small sheets are mixed in the sheet bundle as described above. In this case, even if the paper is bent, it can be determined whether there is an inappropriate paper.

  Note that the movement paths of the first sensor 145 and the second sensor 146 are not necessarily limited to the movement paths described above. The movement path of the first sensor 145 may be a movement path that connects from the position A through the position E to the position D, and the movement path of the second sensor 146 may be a movement path that connects from the position B through the position E to the position C ( (See FIGS. 5A and 5B). Even when such a movement path is adopted, it is possible to detect the presence or absence of a step in a wide range on the upper surface of the sheet bundle. In the case where the paper is bent, it is possible to determine the presence or absence of inappropriate paper.

  Note that a moving mechanism according to an embodiment of the present invention includes the rail unit 16, the sensor driving unit 147, the sensor control unit 101, and the like.

  Next, the operation flow of the image forming apparatus 1 will be described. FIG. 9 is a flowchart showing an operation flow of the image forming apparatus 1.

  When operation control unit 100 accepts an image forming job (YES in step S11), operation control unit 100 starts a paper feed control process (steps S12 to S23).

  First, the operation control unit 100 causes the lifting drive unit 142 to lower the pickup roller 141 (step S12). Thereafter, the sensor control unit 101 causes the sensor driving unit 147 to move the first sensor 145 from the end of the first path (position A in FIG. 5A) to the end on the opposite side (position in FIG. 5A). C) and the second sensor 146 is moved from the end of the second path (position B in FIG. 5A) to the opposite end (position D in FIG. 5A). (Step S13)

  The determination unit 102 acquires output signals output from the first sensor 145 and the second sensor 146 while the first sensor 145 and the second sensor 146 are moving in the process of step S13 (step S14). Then, the determination unit 102 determines whether there is an inappropriate sheet in the sheet bundle based on the acquired output signal (step S15).

  If it is determined in step S15 that there is inappropriate paper (YES in step S16), the operation control unit 100 stops the image forming job (step S20). And the alerting | reporting control part 103 performs the warning alerting | reporting process defined beforehand (step S21). For example, the notification control unit 103 causes the display unit 473 to display a predetermined notification screen D1 as illustrated in FIG.

  If the paper feed cassette 15 is reset after the warning notification process (YES in step S22), the operation control unit 100 resumes the image forming job stopped in the process of step S20 (step S23), and the process of step S13. Return to processing. In other words, the determination unit 102 determines again whether or not there is an inappropriate sheet in the sheet bundle.

  On the other hand, when it is determined that there is no inappropriate paper in the process of step S15 (NO in step S16), the operation control unit 100 rotates the pickup roller 141 and the transport roller 171 so that one sheet is fed from the sheet bundle. Paper is fed (step S17). Then, the operation control unit 100 causes the image forming unit 12 to form an image on the paper fed from the paper feeding unit 14 (step S18). Thereafter, when the image forming job is not completed (NO in step S19), the process returns to step S13. In other words, the determination unit 102 determines again whether or not there is an inappropriate sheet in the sheet bundle. As described above, in the image forming apparatus 1, when a plurality of sheets are to be fed, the presence or absence of an inappropriate sheet in the sheet bundle is determined every time one sheet is fed.

  When a plurality of sheets are to be fed, the sensor control unit 101 causes the sensor driving unit 147 to place the first sensor 145 and the second sensor 146 at the end of the first path or the second path. After the movement, the first sensor 145 and the second sensor 146 are not returned to the end of the first path or the opposite side of the second path, and after feeding one sheet, the first sensor 145 and the second sensor 146 are returned to the end of the first path or the opposite side of the second path.

  For example, after the sensor control unit 101 moves the first sensor 145 from the position A that is the home position to the position C, the sensor control unit 101 does not immediately return the position to the position A that is the home position. The sensor control unit 101 causes the sensor driving unit 147 to return the first sensor 145 to the position A, which is the home position, when one sheet is subsequently fed. When the first sensor 145 returns to the home position A, the presence or absence of a step on the upper surface of the sheet bundle can be detected, so that the first sensor 145 is returned to the home position every time one sheet is fed. Operation can be omitted.

  The present invention is not limited to the configuration of the above embodiment, and various modifications can be made.

<Modification 1>
FIG. 11 is a flowchart illustrating a flow of operations of the image forming apparatus according to the first modification. The description of the processing having the same contents as the processing shown in the flowchart of FIG. 9 is omitted or simplified.

  In the image forming apparatus 1 according to the above-described embodiment, the presence or absence of an inappropriate sheet in the sheet bundle is determined every time a sheet is fed. Before starting the image forming job, it is determined whether or not there is an inappropriate sheet in the sheet bundle.

  That is, after receiving an image forming job (YES in step S31), the image forming apparatus according to the first modification before starting the paper feeding operation, that is, before the process of lowering the pickup roller 141 (step S36). The process of determining whether or not there is an inappropriate sheet in the sheet bundle shown in steps S32 to S35 is performed.

  Even if improper paper is present on the top surface of the paper bundle, improper paper such as small size paper is mixed inside the paper bundle. A step occurs. For this reason, the image forming apparatus according to the modified example 1 is inferior to the image forming apparatus 1 according to the above embodiment in the accuracy of determining inappropriate paper, but the first sensor 145 and Since it is not necessary to move the second sensor 146, it is possible to reduce the processing time required for the inappropriate paper determination processing.

<Modification 2>
12A and 12B are cross-sectional views illustrating the structure of the sheet feeding unit of the image forming apparatus according to the second modification. In addition, about the structure of the content same as the paper supply part 14 of the image forming apparatus 1 concerning said embodiment shown in FIG. 4, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the above embodiment, the pickup roller 141 is configured to be movable up and down, and the pickup roller 141 is lowered to bring the peripheral surface of the pickup roller 141 into contact with the uppermost surface of the sheet bundle accommodated in the paper feed cassette 15. The case of making it explained was explained. On the other hand, in the image forming apparatus according to the second modification, a part of the mounting surface 151 of the paper feed cassette 15 is a lifting plate 152 that can be lifted and lowered. Then, when the lifting plate 152 is pushed up by the push-up member 157, the sheet bundle P1 accommodated in the sheet cassette 15 is raised, and the uppermost surface of the sheet bundle P1 and the peripheral surface of the pickup roller 141 are brought into contact with each other. (See FIG. 12B).

  In this case, since the elevating plate 152 is pushed up by the inclination angle θ with respect to the placement surface 151 of the paper feed cassette 15, the uppermost sheet of the sheet bundle P1 is also inclined by the inclination angle θ. Therefore, the determination unit of the image forming apparatus according to the second modification uses the inclination angle θ of the lifting plate 152 in addition to the output signals output from the first sensor 145 and the second sensor 146 to determine the upper surface of the sheet bundle. The presence or absence of a step is determined. Specifically, the determination unit corrects the output value of the output signal output from the first sensor 145 and the second sensor 146 with a correction value calculated from the tilt angle θ, and uses the output value after the correction. Then, the presence or absence of a step on the upper surface of the sheet bundle is determined.

<Other variations>
In the above embodiment, the case where two ultrasonic sensors are provided as a configuration for detecting the height of the sheet bundle has been described, but the present invention is not necessarily limited to this case. If the moving paths of the ultrasonic sensors intersect, three or more ultrasonic sensors may be provided.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Control unit 11 Apparatus main body 12 Image forming part 14 Paper feed part 15 Paper feed cassette 16 Rail part 100 Operation control part 101 Sensor control part 102 Determination part 103 Notification control part 141 Pickup roller 142 Lifting drive part 143 Restriction position Detection unit 144 Paper height detection unit 145 First sensor 146 Second sensor 147 Sensor drive unit

Claims (10)

A paper cassette;
A roller for feeding sheets one by one from a bundle of sheets stored in the sheet cassette;
Installed above the paper feed cassette, oscillates ultrasonic waves toward the upper surface of the sheet bundle, receives ultrasonic waves reflected from the upper surface of the sheet bundle, and outputs an output signal corresponding to the received ultrasonic waves. Two ultrasonic sensors to output,
Of the two ultrasonic sensors, one ultrasonic sensor is moved along a first path provided above the paper cassette, and the other ultrasonic sensor is provided above the paper cassette. A moving mechanism for moving along two routes;
A determination unit that determines the presence or absence of inappropriate paper in the paper bundle based on output signals output from the two ultrasonic sensors while the moving mechanism moves the two ultrasonic sensors;
An operation control unit that performs control to stop the paper feeding operation by the roller when the determination unit determines that there is inappropriate paper , and
The sheet feeding device, wherein the first path and the second path intersect above the sheet feeding cassette . The moving mechanism has a rail portion in which two linear rails intersect above the sheet cassette;
The sheet feeding device according to claim 1, wherein the two ultrasonic sensors reciprocate on the rail. A paper cassette;
  A roller for feeding sheets one by one from a bundle of sheets stored in the sheet cassette;
  Installed above the paper feed cassette, oscillates ultrasonic waves toward the upper surface of the sheet bundle, receives ultrasonic waves reflected from the upper surface of the sheet bundle, and outputs an output signal corresponding to the received ultrasonic waves. Two ultrasonic sensors to output,
  Of the two ultrasonic sensors, one ultrasonic sensor is moved along a first path provided above the paper cassette, and the other ultrasonic sensor is provided above the paper cassette. A moving mechanism for moving along two routes;
  A determination unit that determines the presence or absence of inappropriate paper in the paper bundle based on output signals output from the two ultrasonic sensors while the moving mechanism moves the two ultrasonic sensors;
  An operation control unit that performs control to stop the paper feeding operation by the roller when the determination unit determines that there is inappropriate paper, and
  The moving mechanism has a rail portion in which two linear rails intersect above the sheet cassette;
  The two ultrasonic sensors are paper feeding devices that reciprocate on the rail.   The determination unit is located below the first path and the second path based on output signals output from the two ultrasonic sensors while the moving mechanism moves the two ultrasonic sensors. Determining whether or not there is a step on the upper surface of the sheet bundle positioned at the position, determining that there is an inappropriate sheet when determining that there is a difference, and determining that there is no inappropriate sheet when determining that there is no step. The paper feeding device according to any one of claims 1 to 3. In the case where a plurality of sheets are to be fed, the moving mechanism moves the one ultrasonic sensor on the opposite side from the end of the first path every time the roller feeds one sheet. And moving the other ultrasonic sensor from the end of the second path to the opposite end,
5. The determination unit according to claim 1, wherein each time the roller feeds one sheet, the determination unit determines whether there is an inappropriate sheet in the sheet bundle based on the output signal. The paper feeder described in 1.   When a plurality of sheets are to be fed, the moving mechanism moves the two ultrasonic sensors to the end of the first path or the second path, and then the two ultrasonic waves Without returning the sensor to the end of the first path or the opposite side of the second path, after the roller feeds one sheet of paper, the two ultrasonic sensors are moved to the first path. The sheet feeding device according to claim 5, wherein the sheet feeding device is returned to a path or an end portion on the opposite side of the second path. When the sheet feeding cassette is reset after the operation control unit stops the sheet feeding operation by the roller, the moving mechanism moves the one ultrasonic sensor away from the end of the first path. And moving the other ultrasonic sensor from the end of the second path to the opposite end,
The determination unit determines whether or not there is an inappropriate sheet in the sheet bundle based on the output signal;
7. The operation control unit according to claim 1, wherein when the determination unit determines that there is no inappropriate paper, the operation control unit restarts the paper supply operation by the stopped roller. Paper feeder.   The paper feeding device according to any one of claims 1 to 7, further comprising a notification unit that performs a predetermined warning notification when the operation control unit stops the paper feeding operation by the roller. A paper feeding device according to any one of claims 1 to 8,
An image forming apparatus comprising: an image forming unit that forms an image on a sheet fed from the sheet feeding device.   A paper cassette;
  A roller for feeding sheets one by one from a bundle of sheets stored in the sheet cassette;
  Installed above the paper feed cassette, oscillates ultrasonic waves toward the upper surface of the sheet bundle, receives ultrasonic waves reflected from the upper surface of the sheet bundle, and outputs an output signal corresponding to the received ultrasonic waves. Two ultrasonic sensors to output,
  Of the two ultrasonic sensors, one ultrasonic sensor is moved along a first path provided above the paper cassette, and the other ultrasonic sensor is provided above the paper cassette. A moving mechanism for moving along two routes;
  A determination unit that determines the presence or absence of inappropriate paper in the paper bundle based on output signals output from the two ultrasonic sensors while the moving mechanism moves the two ultrasonic sensors;
  An operation control unit that performs control to stop the paper feeding operation by the roller when the determination unit determines that there is inappropriate paper, and
  The determination unit is located below the first path and the second path based on output signals output from the two ultrasonic sensors while the moving mechanism moves the two ultrasonic sensors. A paper feeding device that judges whether or not there is a step on the upper surface of the sheet bundle positioned at the position, determines that there is an inappropriate paper when it is determined that there is a step, and determines that there is no inappropriate paper when it is determined that there is no step .

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