JP2014159339A - Sheet feeding device and image processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet feeding device capable of surely preventing damage caused by driving a lifting plate over an upper limit position, and an image processing apparatus.SOLUTION: An upper limit position sensor 204 is switched between a first detection state and a second detection state in accordance with contact/separation of a sheet placed on a sheet loading surface and a pickup roller. The upper limit position sensor 204 is brought into the first detection state in the state where the sheet placed on the sheet loading surface and the pickup roller are abutted and in the state where the pickup roller is not mounted. A sensor state detection section 401 detects whether the upper limit position sensor 204 is capable of shifting between the first detection state and the second detection state. Only when the upper limit position sensor 204 is in the second detection state and the sensor state detection section 401 detects that the upper limit position sensor 204 is capable of shifting, a drive control section 402 permits raising drive of a lifting plate by a drive section 164.

Description

  The present invention relates to a sheet supply apparatus and an image processing apparatus that supply sheets.

  Sheet supply apparatuses are widely used in image processing apparatuses such as copying machines, facsimile machines, scanners, and multifunction machines. For example, by automatically conveying a plurality of originals one by one to the image reading position using the sheet supply device, the image processing apparatus can read each original continuously. In addition, the image processing apparatus can print each image continuously by automatically transporting the sheet onto which the document image is transferred to the image forming position one by one using the sheet supply device.

  In order to separate the plurality of sheets stacked on the tray one by one, the sheet supply device causes the sheet bundle to contact the pickup roller. Since the thickness of the sheet bundle varies depending on the number of sheets stacked on the tray, the distance between the sheet placement surface and the pickup roller is set to the distance between the sheet placement surface and the pickup roller in order to make the sheet bundle always contact the pickup roller appropriately. It is necessary to adjust according to thickness. For this adjustment, an elevating plate attached to the seating surface so as to be movable up and down can be used. Such a sheet supply device drives the lift plate to push up the sheet bundle on the lift plate and bring it into contact with the pickup roller. The pickup roller sends out the contacted sheet.

  The stop position of the lifting plate when the sheet is fed is detected by an upper limit position sensor. The upper limit position sensor detects whether or not the upper surface of the sheet bundle is in contact with the pickup roller. When the contact between the upper surface of the sheet bundle and the pickup roller is detected by the upper limit position sensor, the lifting of the elevating plate stops. For example, in a sheet feeding apparatus having a mechanism in which a pickup roller rises as the elevating plate rises after contacting the upper surface of a sheet bundle, the upper limit position sensor determines the position of the pickup roller or a member that moves in conjunction with the pickup roller. By detecting, the stop position is detected.

  As the sheet conveyance proceeds, the thickness of the sheet bundle decreases. When the number of sheets is large, when the thickness of the sheet bundle is reduced, the pickup roller cannot feed out the lower sheets. For this reason, in the sheet supply apparatus, for example, when the thickness of the sheet bundle decreases by a predetermined amount, the lifting plate is driven to push up the sheet bundle. As a result, the upper surface of the sheet bundle is properly brought into contact with the pickup roller again, and stable sheet feeding can be realized. The raising / lowering of the elevating plate during sheet conveyance is performed in response to a change in the detection state of the above-described upper limit position sensor, for example.

  When all the sheets on the tray are sent out and the sheet set sensor that detects the presence or absence of the sheets on the tray enters a sheet non-detection state (no sheets), the lifting plate is driven to the sheet setting position for stacking new sheets. The Further, when the sheet is placed on the tray, the elevating plate is driven to the sheet setting position. The sheet set position is normally the lower limit of the lifting range of the lifting plate, and the downward driving is performed until the lifting plate is detected by a lower limit position sensor provided at a position facing the lower surface of the lifting plate.

  On the other hand, in recent image processing apparatuses, when no operation is performed for a certain period of time or when a predetermined button on the operation panel is pressed, the operation shifts from a normal standby state to a so-called power saving mode that further reduces power consumption. Technology is adopted. For example, in a power saving mode in an image processing apparatus having a printing function such as a copying machine or a multifunction machine, the power source of a fixing heater or the like that consumes a large amount of power is turned off or switched to low power operation. Further, since it is not necessary to supply power to the sheet supply apparatus during the power saving mode, the power of the sheet supply apparatus is also turned off. Then, when returning from the energy saving mode to the normal standby mode (standby mode), or when the main power of the image processing apparatus is turned on, the sheet supply apparatus is turned on.

  At this time, the image processing apparatus executes an initialization operation (function confirmation operation) of each unit in order to ensure the normal operation of the sheet supply apparatus. For example, in the sheet supply apparatus, the state of sensors arranged in various places on the sheet conveyance path is confirmed, or when a sheet is stacked on the tray, the sheet is mounted on the tray so that the sheet supply can be started immediately. An operation of bringing the sheet and the pickup roller into contact with each other is performed (see, for example, Patent Documents 1 to 4).

JP 2005-67853 A JP 2002-255396 A JP-A-8-96894 JP 2008-151715 A

  In recent years, there has also been an image processing apparatus including a large capacity paper tray (sheet supply apparatus). In such a large-capacity paper tray, a large amount of paper is stacked on the lifting plate, and therefore a motor with a large torque is used as a driving device for driving the lifting plate. Since the motor having such a large torque is used, the elevating plate reaches a position where the sheet and the pickup roller contact each other (hereinafter, referred to as an upper limit position as appropriate) due to, for example, detection abnormality of the upper limit position sensor. If the driving of the motor is not stopped in spite of the above, as disclosed in Patent Documents 1 and 2, the members constituting the driving system and the members with which the elevating plate reaching the upper limit position are in contact May be damaged.

  For example, the upper limit position sensor, which is often used in image processing apparatuses and detects the arrival of the upper limit position by moving the pickup roller in the vertical direction, removes the pickup roller from the large-capacity paper tray for maintenance, and the maintenance is completed. In such a case, if the pickup roller is forgotten to be mounted, such an abnormal detection of the upper limit position sensor may occur. That is, since the pickup roller is not mounted, the pickup roller does not move even when the lifting plate is raised. Therefore, it cannot be detected that the lift plate has reached the upper limit position. As the configuration of the upper limit position sensor that detects the vertical movement of the pickup roller, for example, a configuration in which a light shielding plate that switches between an on state and an off state in a photo interrupter is used to change the state in conjunction with the vertical movement of the pickup roller is used. Has been.

  For example, it is possible to detect the forgetting to attach the pickup roller itself by applying the forgetting to detect detection technique disclosed in Patent Documents 3 and 4 above. However, since there are concerns about an increase in cost due to an increase in the number of parts and an increase in failure probability due to a complicated structure, it is desirable to be able to detect forgetting to mount the pickup roller without increasing the number of parts. Therefore, a configuration is adopted in which the detection state of the upper limit position sensor is the same in the state where the upper and lower plates reach the upper limit position and the state where the pickup roller is not mounted. That is, when the pickup roller is brought into contact with the pickup roller and the pickup roller is raised, and when the pickup roller is not attached, the light shielding plate is present at the non-light shielding position of the photo interrupter (on state), and the pickup roller is attached and When the pickup roller and the paper are not in contact with each other, the light shielding plate is in the light shielding position (off state). In this configuration, since the detection state of the upper limit position sensor is the same in the state where the upper and lower plates reach the upper limit position and the state where the pickup roller is not mounted, the lifting plate can be prevented from rising when the pickup roller is not mounted.

  However, even when such a configuration is adopted, the drive of the motor is not stopped regardless of whether the elevating plate has reached the upper limit position, and the members constituting the drive system and the upper limit position are reached. In some cases, the members that are in contact with the raised and lowered plates are damaged.

  The present invention has been made in view of the problems of the prior art as described above, and can reliably prevent driving of the lifting plate exceeding the upper limit position without adopting a complicated structure. It is another object of the present invention to provide an image processing apparatus.

  In order to achieve the above object, the present invention employs the following technical means. That is, the sheet supply apparatus according to the present invention includes a lift plate, a drive unit, a pickup roller, an upper limit position sensor, a light shielding plate, a sensor state detection unit, and a drive control unit. The elevating plate is attached to the seating surface of the sheet so as to be movable up and down. The driving unit drives the lifting plate up and down. The pickup roller is detachably provided above the elevating plate, and abuts against the upper surface of the sheet mounted on the mounting surface to send out the sheet. The upper limit position sensor is a photosensor including a light emitting unit and a light receiving unit. The light shielding plate includes a locking portion and a light shielding portion. The light-shielding portion is provided with a rotation shaft parallel to a drive shaft that rotationally drives the pickup roller, and the light-shielding plate rotates around the rotation shaft as the pickup roller moves up and down. The locking portion is locked to the drive shaft that rotationally drives the pickup roller, and moves with the vertical movement of the pickup roller, and the light emitting portion and the light receiving portion of the upper limit position sensor. The light shielding part is inserted into and removed from the part with the vertical movement of the pickup roller. In a state where the sheet bundle on the lifting plate and the pickup roller are separated from each other, the light shielding portion is inserted between the light emitting portion and the light receiving portion, and the upper limit position sensor is in a second detection state, In a state where the sheet bundle on the lift plate and the pickup roller are in contact with each other, the light shielding portion is extracted from between the light emitting portion and the light receiving portion, and the upper limit position sensor is in the first detection state. Become. When the pickup roller is detached, the light shielding part is extracted from between the light emitting part and the light receiving part, and the upper limit position sensor is in the first detection state. The sensor state detection unit detects whether or not the upper limit position sensor can transition between the first detection state and the second detection state. The drive control unit allows the drive unit to move upward only when the upper limit position sensor is in the second detection state and the sensor state detection unit detects that the upper limit position sensor is capable of transition. .

  In this configuration, only when the upper limit position sensor is capable of transitioning between the first detection state and the second detection state, the lifting plate is not in the upper limit position reaching state, and the pickup roller is not in the unmounted state. Ascent is permitted. Therefore, it is possible to reliably prevent the lifting plate from being driven beyond the upper limit position.

  In the sheet feeding device, when the sheet bundle on the lifting plate and the pickup roller are separated from each other, the light shielding unit is inserted between the light emitting unit and the light receiving unit only by the weight of the pickup roller. The upper limit position sensor is particularly preferably in the second detection state. Further, in this configuration, the sensor state detection unit can employ a configuration that detects whether or not the upper limit position sensor can transition based on the drive current of the light emitting unit of the photosensor. With this configuration, it is possible to reliably prevent the lifting plate from being driven beyond the upper limit position with a very simple configuration.

  On the other hand, in another aspect, the present invention can also provide an image processing apparatus including the above-described sheet supply apparatus.

  According to the present invention, it is possible to reliably prevent the elevating plate from being driven beyond the upper limit position, and to damage the members constituting the elevating drive system of the elevating plate or the members that are in contact with the elevating plate that has reached the upper limit position. It can be surely prevented.

1 is a schematic configuration diagram showing the overall configuration of a multifunction machine according to an embodiment of the present invention. FIG. 2 is an enlarged schematic view showing a main part of a multifunction machine according to an embodiment of the present invention. The figure which shows the hardware constitutions of the multifunctional device in one Embodiment of this invention. 1 is a functional block diagram showing a multifunction machine according to an embodiment of the present invention. The block diagram which shows an example of the structure which implement | achieves the sensor state detection in one Embodiment of this invention FIG. 5 is a flowchart showing an example of a sheet conveyance procedure performed by the multifunction machine according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. In the following, the present invention is embodied as a paper supply device for a digital multi-function peripheral.

  FIG. 1 is a schematic configuration diagram illustrating an example of the overall configuration of a digital multifunction peripheral according to the present embodiment. As shown in FIG. 1, the multifunction peripheral 100 includes a main body 101 including an image reading unit 120 and an image forming unit 140, and a platen cover 102 attached above the main body 101. A document table 103 is provided on the upper surface of the main body 101, and the document table 103 is opened and closed by a platen cover 102. Further, the platen cover 102 includes a document conveying device 110. An operation panel 200 is provided on the front surface of the multi-function device 100 so that the user can give a copy start or other instruction to the multi-function device 100, and can check the status and settings of the multi-function device 100.

  An image reading unit 120 is provided below the document table 103. The image reading unit 120 reads an image of a document with the scanning optical system 121 and generates digital data (image data) of the image. The document can be placed on the document table 103 or the document transport device 110. The scanning optical system 121 includes a first carriage 122, a second carriage 123, and a condenser lens 124. The first carriage 122 is provided with a linear light source 131 and a mirror 132, and the second carriage 123 is provided with mirrors 133 and 134. The light source 131 illuminates the document. The mirrors 132, 133, and 134 guide reflected light from the document to the condenser lens 124, and the condenser lens 124 forms an optical image on the light receiving surface of the line image sensor 125. In the scanning optical system 121, the first carriage 122 and the second carriage 123 are provided so as to be able to reciprocate in the sub-scanning direction 135. By moving the first carriage 122 and the second carriage 123 in the sub-scanning direction 135, the image of the document placed on the document table 103 can be read by the image sensor 125. When reading an image of a document set on the document conveying device 110, the image reading unit 120 temporarily fixes the first carriage 122 and the second carriage 123 according to the image reading position, and passes the image reading position. Are read by the image sensor 125. The image sensor 125 generates image data of a document corresponding to, for example, each color of R (red), G (green), and B (blue) from the light image incident on the light receiving surface. The generated image data can be printed on paper in the image forming unit 140. Further, it can also be transmitted to another device (not shown) through the network 172 by the network interface 171.

  The image forming unit 140 prints image data obtained by the image reading unit 120 or image data received from another device connected to the network 172 on a sheet. The image forming unit 140 includes a photosensitive drum 141. The photosensitive drum 141 rotates in one direction at a constant speed. Around the photosensitive drum 141, a charger 142, an exposure unit 143, a developing unit 144, and an intermediate transfer belt 145 are arranged in this order from the upstream side in the rotation direction. The charger 142 uniformly charges the surface of the photosensitive drum 141. The exposure device 143 irradiates the surface of the uniformly charged photoconductor drum 141 with light according to the image data, and forms an electrostatic latent image on the photoconductor drum 141. The developing device 144 attaches toner to the electrostatic latent image and forms a toner image on the photosensitive drum 141. The intermediate transfer belt 145 transfers the toner image on the photosensitive drum 141 onto a sheet. When the image data is a color image, the intermediate transfer belt 145 transfers each color toner image onto the same sheet. The RGB color image is converted into C (cyan), M (magenta), Y (yellow), and K (black) format image data, and the image data of each color is input to the exposure unit 143.

  The image forming unit 140 feeds paper from the manual feed tray 151, the paper supply devices 152, 153, and 154 to the transfer unit between the intermediate transfer belt 145 and the transfer roller 146. Various sizes of paper can be placed or stored in the manual feed tray 151 and the paper supply devices 152, 153, and 154. The image forming unit 140 selects a sheet specified by the user or a sheet corresponding to the automatically detected document size, and feeds the selected sheet from the manual feed tray 151 and the sheet supply devices 152, 153, and 154 by the pickup roller 155. To do. The fed paper is transported to the transfer section by transport rollers 156 and registration rollers 157. The sheet on which the toner image is transferred is conveyed to the fixing device 148 by the conveyance belt 147. The fixing device 148 has a fixing roller 158 and a pressure roller 159 with a built-in heater, and fixes the toner image on the sheet by heat and pressing force. The image forming unit 140 discharges the sheet that has passed through the fixing device 148 to the discharge tray 149.

  In the example of FIG. 1, the paper supply device 154 is a large capacity tray. The paper supply device 154 can store 1,000 sheets or more of paper 162 (referred to as a paper bundle as appropriate) therein, and the paper bundle is stacked on an elevating plate 161 that can be moved up and down provided in the paper supply device 154. The The elevating plate 161 moves up and down by driving a motor (driving unit) 164 constituting the elevating drive mechanism 163. When feeding the paper 162, the elevating drive mechanism 163 drives the elevating plate 161 to raise the paper bundle on the elevating plate 161 and bring it into contact with the pickup roller 155. The pick-up roller 155 sends out the paper 162 that is in contact with the pickup roller 155 one by one.

  When all the paper on the lifting plate 161 is sent out and the paper set sensor 166 that detects the presence or absence of the paper on the lifting plate 161 enters a paper non-detection state, the lifting plate 161 is in the paper setting position for stacking new paper. Driven. The paper set sensor 166 includes, for example, a transmissive photosensor (photointerrupter) in which a light emitting portion and a light receiving portion are arranged to face each other, and a reflective photosensor (photoreflector) in which the light emitting portion and the light receiving portion are arranged on one surface. It is possible to configure using a non-contact sensor such as a micro sensor or a contact sensor such as a micro switch. In the example shown in FIG. 1, the paper set sensor 166 is disposed on the back side of the lifting plate 161. However, if the presence or absence of the paper on the lifting plate 161 can be detected, the placement position is arbitrary. For example, it can also be arranged on the side or upper side of the lifting plate 161.

  For example, when a transmissive photosensor is used as the paper set sensor 166, a state in which the light emitted from the light emitting unit reaches the light receiving unit and a light shielding plate is inserted between the light emitting unit and the light receiving unit to The state in which the emitted light does not reach the light receiving unit corresponds to the case where the paper is placed on the lifting plate 161 and the case where the paper is not placed, respectively. Be placed. In this case, the light-shielding plate is inserted between the light-emitting portion and the light-receiving portion in accordance with the contact and separation between the member placed so as to contact the paper placed on the lifting plate 161 and the paper. The position and a non-insertion position arranged other than between the light emitting unit and the light receiving unit are moved.

  The sheet setting position is the lower limit of the lifting range of the lifting plate 161, and the downward driving is performed by the lower limit position sensor 165 provided at the lower end of the lifting drive mechanism 163 so as to face the lower surface of the lifting plate 161. Until it is detected. The lower limit position sensor 165 can be configured using, for example, a non-contact type sensor such as the above-described transmission type photo sensor or reflection type photo sensor, or a contact type sensor such as a micro switch. Note that the arrangement position of the lower limit position sensor 165 is arbitrary as long as the arrival of the lower limit position of the elevating plate 161 can be detected.

  On the other hand, the stop position of the lifting plate 161 when the paper is fed is detected by an upper limit position sensor. The upper limit position sensor detects whether or not the upper surface of the sheet bundle is in contact with the pickup roller 155. In the present embodiment, the pickup roller 155 has a configuration in which the pickup roller 155 is brought into contact with the upper surface of the sheet bundle and then ascends with the ascending / descending plate 161 (that is, a structure that can move up and down with the contact with and separation from the sheet bundle). Have. The upper limit position sensor detects whether the pickup roller 155 is in contact with the upper surface of the sheet bundle by detecting the vertical movement of the pickup roller 155.

  FIG. 2 is an enlarged view showing the vicinity of the pickup roller 155 of the paper supply device 154. 2A and 2B show a state in which the sheet bundle on the lifting plate 161 and the pickup roller 155 are separated from each other. FIGS. 2C and 2D show the lifting and lowering. A state where the sheet bundle on the plate 161 and the pickup roller 155 are in contact with each other is shown. 2 (a) and 2 (c) are enlarged schematic views of the pickup roller 155 portion of FIG. 1, and FIGS. 2 (b) and 2 (d) are FIGS. 2 (a) and 2 (d), respectively. This corresponds to the right side view of 2 (c). Note that in FIG. 2D, the position of the pickup roller 155 in FIG.

  As shown in FIG. 2A to FIG. 2D, the upper limit position sensor 204 is constituted by a transmissive photosensor. The light shielding plate 203 is inserted and removed between the light emitting unit 204a and the light receiving unit 204b of the upper limit position sensor 204 as the pickup roller 155 moves up and down. The light shielding plate 203 includes a locking portion 203a and a light shielding portion 203b. The locking portion 203a is locked to a drive shaft 201 that rotationally drives the pickup roller 155, and moves as the pickup roller 155 moves up and down. The drive shaft 201 is configured to rotate (idle) independently of the locking portion 203a, and the locking portion 203a does not rotate even when the drive shaft 201 rotates. For example, the light shielding plate 203 may be disposed at one end of the drive shaft 201 so that the pickup roller 155 does not come into contact with the sheet conveyed. Further, as long as the light shielding plate 203 moves in conjunction with the vertical movement of the pickup roller 155, the locking portion 203 a may be connected to a portion other than the drive shaft 201.

  The light shielding portion 203b is provided with a rotation shaft 202 parallel to the drive shaft 201, and the light shielding plate 203 rotates around the rotation shaft 202 as the pickup roller 155 moves up and down. As shown in FIGS. 2 (a) and 2 (c), the light shielding portion 203b has a fan-like shape in front view. Then, in response to the rotation of the light shielding plate 203 accompanying the vertical movement of the pickup roller 155, the light shielding portion 203b is inserted and removed between the light emitting portion 204a and the light receiving portion 204b of the upper limit position sensor 204. That is, as shown in FIGS. 2A and 2B, when the sheet bundle on the lifting plate 161 and the pickup roller 155 are separated from each other, the light shielding portion 203b of the light shielding plate 203 is the light emitting portion 204a. And the light receiving unit 204b. In this case, the upper limit position sensor 204 is in a light shielding state (off state: second detection state). On the other hand, as shown in FIGS. 2C and 2D, when the sheet bundle on the lifting plate 161 and the pickup roller 155 are in contact with each other, the light shielding portion 203b of the light shielding plate 203 is the light emitting portion 204a. And the light receiving unit 204b. In this case, the upper limit position sensor 204 is in a light receiving state (on state: first detection state).

  In the present embodiment, the pickup roller 155 is detachably provided in the multi-function device 100 for maintenance or the like. When the pickup roller 155 is detached, the upper limit position sensor 204 is in the same detection state (FIG. 2 (c) and FIG. 2 (2) as the state where the sheet bundle on the lifting plate 161 is in contact with the pickup roller 155. (first detection state shown in d)). In such a configuration, for example, when the sheet bundle on the lifting plate 161 and the pickup roller 155 are separated from each other, the pickup roller shown in FIGS. It can be easily realized by adopting a configuration in which the position of 155 is maintained.

  FIG. 3 is a hardware configuration diagram of a control system in the multifunction machine. The multifunction peripheral 100 according to the present embodiment includes a CPU (Central Processing Unit) 301, a RAM (Random Access Memory) 302, a ROM (Read Only Memory) 303, an HDD (Hard Disk Drive) 304, an original transport device 110, and an image reading unit 120. A driver 305 corresponding to each drive unit in the image forming unit 140 is connected via an internal bus 306. The ROM 303, the HDD 304, and the like store programs, and the CPU 301 controls the multifunction peripheral 100 in accordance with the instructions of the control program. For example, the CPU 301 uses the RAM 302 as a work area, and controls the operation of each driving unit by exchanging data and commands with the driver 305. The HDD 304 is also used for storing image data obtained by the image reading unit 120 and image data received from an external device through the network interface 171.

  An operation panel 200 and various sensors 307 are also connected to the internal bus 306. The operation panel 200 receives a user operation and supplies a signal based on the operation to the CPU 301. Further, the operation panel 200 displays an operation screen on a display provided in the operation panel 200 according to a control signal from the CPU 301.

  FIG. 4 is a functional block diagram of the MFP according to the present embodiment. As shown in FIG. 4, the multifunction peripheral 100 of this embodiment includes a sensor state detection unit 401 and a drive control unit 402.

  The sensor state detection unit 401 detects whether or not the upper limit position sensor 204 described above can transition between the first detection state (here, the on state) and the second detection state (here, the off state). To do. In addition, the drive control unit 402 determines that the motor 164 only when the upper limit position sensor 204 is in the second detection state (off state) and the sensor state detection unit 401 detects that the upper limit position sensor 204 can transition. The raising / lowering plate 161 is allowed to rise.

  FIG. 5 is a diagram illustrating specific examples of the upper limit position sensor 204, the sensor state detection unit 401, and the drive control unit 402. As described above, the upper limit position sensor 204 includes a transmissive photosensor, and includes the light emitting unit 204a including a light emitting diode and the light receiving unit 204b including a phototransistor. A power supply voltage (here, 3.3V) is applied to the anode of the light emitting diode 204a via a current limiting resistor 502, and a power supply voltage (here, 3.V) is applied to the collector of the phototransistor 204b via a pull-up resistor 503. 3V) is applied. The cathode of the light emitting diode 204a and the emitter of the phototransistor 204b are grounded. In this configuration, the upper limit position sensor 204 is detachably attached to the multifunction peripheral 100 via the connector 501.

  In this configuration, the drive control unit 402 determines whether the upper limit position sensor 204 is on or off based on the potential between the pull-up resistor 503 and the collector of the phototransistor 204b. When the upper limit position sensor 204 is on, the phototransistor 204b is in a conducting state. Therefore, in FIG. 5, the potential between the pull-up resistor 503 and the collector of the phototransistor 204b is almost the ground potential (Low level). On the other hand, when the upper limit position sensor 204 is in an off state, the phototransistor 204b is in a cutoff state. Therefore, in FIG. 5, the potential between the pull-up resistor 503 and the collector of the phototransistor 204b is almost the power supply potential (High level). In this example, the drive control unit 402 determines that the upper limit position sensor 204 is on when the potential between the pull-up resistor 503 and the collector of the phototransistor 204b is at a low level. Further, when the potential between the pull-up resistor 503 and the collector of the phototransistor 204b is at a high level, it is determined that the upper limit position sensor 204 is in an off state.

  In addition, the sensor state detection unit 401 detects whether or not the upper limit position sensor 204 can transition between the on state and the off state based on the potential between the current limiting resistor 502 and the anode of the light emitting diode 204a. To do. When the upper limit position sensor 204 can transition between the on state and the off state, a driving current (diode current) flows through the light emitting diode 204a. Therefore, in FIG. 5, the potential between the current limiting resistor 502 and the anode of the light emitting diode 204a is a potential corresponding to the ratio between the internal resistance of the light emitting diode 204a and the current limiting resistor 502. Therefore, the potential between the current limiting resistor 502 and the anode of the light emitting diode 204a is lower (Low level) than the power supply voltage (here, 3.3V). On the other hand, when no diode current flows through the light emitting diode 204a, the potential between the current limiting resistor 502 and the anode of the light emitting diode 204a in FIG. 5 is almost the power supply potential (High level). In this example, the sensor state detection unit 401 can transition between the on state and the off state of the upper limit position sensor 204 when the potential between the current limiting resistor 502 and the anode of the light emitting diode 204a is at a low level. Detect that there is. Further, the sensor state detection unit 401 indicates that the upper limit position sensor 204 cannot transition between the on state and the off state when the potential between the current limiting resistor 502 and the anode of the light emitting diode 204a is at a high level. Detect.

  In addition, as illustrated in FIG. 4, the multifunction peripheral 100 according to the present embodiment includes a notification unit 403 and a door set sensor 411. The notification unit 403 notifies the user of an alarm according to the detection result of the sensor state detection unit 401. The alarm can be implemented by any method that can notify the user, such as display or voice. For example, the notification unit 403 can execute a notification to the user by displaying a warning message on a display included in the operation panel 200.

  The door set sensor 411 detects the open / close state of an open / close door provided at the front portion of the paper supply device 154. As described above, when the paper set sensor 166 enters the paper non-detection state, the elevating plate 161 is driven to a paper set position for stacking new paper. At this time, the user opens the door of the paper supply device 154 to replenish paper, and closes the door after replenishment. The door set sensor 411 detects such an open / closed state of the door. The door set sensor 411 can be configured using, for example, a non-contact type sensor such as a transmission type photo sensor or a reflection type photo sensor, or a contact type sensor such as a micro switch. In addition, the arrangement position of the door set sensor 411 is arbitrary as long as the open / closed state of the door can be detected. Although not particularly limited, in this embodiment, regardless of the detection state of the paper set sensor 166, when the door of the paper supply device 154 is opened, the elevating plate 161 is driven to the paper setting position. ing.

  FIG. 6 is a flowchart illustrating an example of a sheet conveyance procedure executed by the multifunction peripheral 100. The procedure is started, for example, when the main power supply of the multifunction peripheral 100 is turned on, when the power saving mode is shifted to the standby mode, or when the door set sensor 411 is changed from the open state to the closed state.

  When the procedure is started, the drive control unit 402 confirms the state of the paper set sensor 166 (step S601). If the sheet is not detected, the drive control unit 402 drives the lifting plate 161 downward to the sheet setting position, and the procedure ends (No in steps S601 and S608). On the other hand, if the paper set sensor 166 is in the paper detection state, the drive control unit 402 next checks the state of the upper limit position sensor 204 (steps S601 Yes, S602).

  First, the procedure when the main power supply of the multifunction peripheral 100 is turned on and when the power saving mode is shifted to the standby mode will be described. In these cases, the lifting plate 161 of the paper supply device 154 remains in the state when the main power source of the multifunction peripheral 100 is turned off or when the mode is shifted to the power saving mode. That is, if the elevator plate 161 is not driven down when the main power supply of the multifunction peripheral 100 is cut off or when the power saving mode is entered, the elevator plate 161 is picked up by the upper surface of the sheet bundle on the elevator plate 161 and the pickup. The roller 155 is in a contact position. In this case, if there is no abnormality in the upper limit position sensor 204, the upper limit position sensor 204 should be on.

  When the upper limit position sensor 204 is in the ON state, the drive control unit 402 prohibits the lifting operation of the lifting plate 161 (steps S602 Yes, S605). When the upper limit position sensor 204 is on, the light emitting unit 204a of the upper limit position sensor 204 emits light normally, and the light is received by the light receiving unit 204b. That is, there is no abnormality in the upper limit position sensor 204. Therefore, this state is maintained until the paper set sensor 166 enters a paper non-detection state by paper conveyance or until the upper limit position sensor 204 changes from an on state to an off state (No in steps S606 and S601).

  In this state, when the paper on the lift plate 161 is conveyed and the paper set sensor 166 enters a paper non-detection state, the drive control unit 402 drives the lift plate 161 to the paper setting position, and the procedure ends (No in step S601). , S608). Further, when the sheet on the elevating plate 161 is conveyed and the sheet setting sensor 166 remains in the sheet detection state, and the upper limit position sensor 204 changes from the on state to the off state, the drive control unit 402 turns on the upper limit position sensor 204. The detection result by the sensor state detection unit 401 as to whether or not the transition between the state and the off state is possible is confirmed (steps S601 Yes, S602 No, S603).

  When the detection result can be changed, the drive control unit 402 drives the elevating plate 161 up by the motor 164 (Yes in Steps S603 and S609). As long as the detection result by the sensor state detection unit 401 can transition, the drive control unit 402 continues to drive the lifting plate 161 while the upper limit position sensor 204 is in the off state (steps S602 No, S603 Yes, S609). When the upper limit position sensor 204 changes from the off state to the on state, the drive control unit 402 stops the ascending drive (steps S602 Yes, S605). As described above, this state is maintained until the paper set sensor 166 enters the paper non-detection state due to paper conveyance or until the upper limit position sensor 204 changes from the on state to the off state (No in steps S606 and S601).

  When the upper limit position sensor 204 is in the OFF state and the detection result by the sensor state detection unit 401 becomes impossible to transition, the drive control unit 402 prohibits the lifting operation of the lifting plate 161 (Steps S602No, S603No, S604, S605). Further, the detection result that the sensor state detection unit 401 does not allow transition indicates that the light emitting unit 204a of the upper limit position sensor 204 is not emitting light. That is, the upper limit position sensor 204 is in a state where it cannot transition from the off state to the on state, and an abnormality has occurred in the upper limit position sensor 204 (step S606 Yes). In this case, the notification unit 403 issues an alarm based on the detection result of the sensor state detection unit 401. Here, the notification unit 403 displays a warning message indicating that the upper limit position sensor 204 is abnormal on the display of the operation panel 100 (step S607). Further, although not particularly limited, in the present embodiment, when an abnormality occurs in the upper limit position sensor 204, the drive control unit 402 is configured to drive the elevating plate 161 downward to the paper setting position by the motor 164. (Step S608).

  Next, a procedure when the door set sensor 411 changes from the open state to the closed state will be described. When the door set sensor 411 changes from the open state to the closed state, the lift plate 161 is at the lower limit of the lift range of the lift plate 161 that is the paper setting position as described above. In this case, if there is no abnormality in the upper limit position sensor 204, the upper limit position sensor 204 should be in an off state (No in steps S601 and S602).

  When the upper limit position sensor 204 is in the off state, as described above, the drive control unit 402 determines whether or not the upper limit position sensor 204 can transition between the on state and the off state. The detection result is confirmed (No in steps S602 and S603).

  At this time, if the detection result by the sensor state detection unit 401 is not transitionable, the drive control unit 402 prohibits the lifting operation of the lifting plate 161, and the notification unit 403 issues an alarm (steps S603 No, S604, S605, S607). In this case, since the elevating plate 161 is at the paper setting position, the procedure ends as it is (step S608). On the other hand, when the detection result by the sensor state detection unit 401 is transitionable, the drive control unit 402 drives to raise and lower the lifting plate 161 as described above (steps S603 Yes, S609, and S602). The subsequent procedure is also as described above.

  As described above, in the multifunction machine 100, the upper limit position sensor 204 can transition between the on state (first detection state) and the off state (second detection state), and the upper limit position sensor 204 is in the off state. (Second detection state), that is, the lifting of the lifting plate 161 is permitted only when the lifting plate 161 is not in the upper limit position reached state and the pickup roller 155 is not in the unmounted state. Therefore, the driving of the elevating plate 161 exceeding the upper limit position can be reliably prevented. As a result, it is possible to reliably prevent damage to the members that constitute the lifting drive system of the lifting plate 161 and the members that are in contact with the lifting plate 161 that has reached the upper limit position due to the driving of the lifting plate 161 exceeding the upper limit position. Can do.

  In the above embodiment, the upper limit position sensor 204 is configured by a transmissive photosensor. However, the presence or absence of an object is detected based on light other than a reflective photosensor, infrared (electromagnetic wave), capacitance, magnetic field, or the like. Other configurations of sensors can be used. However, from the viewpoint of simplifying the configuration, a transmissive or reflective photosensor is employed as the upper limit position sensor 204, and the pickup roller 155 is in a state where the sheet bundle mounted on the lifting plate 161 is in contact with the pickup roller 155. It is preferable to adopt a configuration in which the light receiving portion of the photosensor receives light from the light emitting portion (on state) in a state where it is not attached. For example, when a reflection type photosensor is employed, a reflection plate is provided in the light shielding portion 203 in FIG. 2, and in the state of FIG. 2A, the photosensor and the reflection plate are not opposed to each other, and FIG. In this state, the reflection type photosensor may be arranged so that the photosensor and the reflection plate are turned on.

  As described above, in the multi-function machine 100, when the thickness of the sheet bundle decreases due to sheet conveyance and the detection state of the upper limit position sensor 204 changes, the elevating plate 161 rises. When the detection state changes, the lifting plate 161 stops. Therefore, when a sheet is present on the lifting plate 161, the state where the sheet bundle mounted on the lifting plate 161 and the pickup roller 155 are in contact can be said to be a normal state. If the upper limit position sensor 204 is configured to be in the on state in such a normal state, the upper limit position sensor 204 is normal when the main power of the multifunction peripheral 100 is turned on or when the power saving mode is shifted to the standby mode. It is extremely useful because it can be checked as it is in the ON state. In addition, when a photosensor is used, it can be confirmed whether or not the light emitting unit emits light depending on whether or not the drive current of the light emitting unit is flowing, and therefore, between the first detection state and the second detection state. It is possible to determine whether or not the transition is possible without actually transitioning. Therefore, the above-described effects can be obtained with a very simple configuration.

  For example, in the example illustrated in FIG. 5, the drive control unit 402 can be realized as a CPU that executes a program stored in a ROM or RAM. In this case, when the CPU includes an analog-digital conversion port, the analog-digital conversion port can function as the sensor state detection unit 401. That is, the potential between the current limiting resistor 502 and the anode of the light emitting diode 204a in FIG. 5 is input to the analog-digital conversion port, and a digital value generated according to the input, the pull-up resistor 503, and the phototransistor 204b. The flow shown in FIG. 6 can be realized very easily by a logical operation with a digital value obtained as a potential between the collector and the collector. Further, in this configuration, an analog output type photosensor can be used as the upper limit position sensor 204, so that it can be configured at a very low cost.

  As described above, according to the present invention, it is possible to reliably prevent the elevating plate from being driven beyond the upper limit position, and the members constituting the elevating drive system of the elevating plate and the elevating plate reaching the upper limit position abut. It is possible to reliably prevent breakage of the members.

  The above-described embodiments do not limit the technical scope of the present invention, and various modifications and applications other than those already described are possible within the scope of the present invention. For example, in the MFP 100, the configuration including the notification unit 403 has been described as a particularly preferable form. However, even if the configuration does not include the notification unit 403, it is possible to reliably prevent driving of the lifting plate exceeding the upper limit position. Is possible.

  In the flowchart shown in FIG. 6, the order of the steps can be changed as appropriate within the range where the equivalent action is achieved. For example, in the above embodiment, the upper limit position sensor is configured to determine whether or not the upper limit position sensor can transition when the upper limit position sensor is in an off state. Even if it is determined whether or not it is in the ON state, it can be configured to produce the same effect.

  In addition, in the above-described embodiment, the present invention is embodied as a paper supply device of a digital multifunction peripheral. However, the paper supply of an arbitrary image processing apparatus having a printing function such as a printer, a copying machine, etc. The present invention can also be applied to a document supply apparatus of an image reading apparatus such as a facsimile or a scanner.

  According to the present invention, it is possible to reliably prevent breakage of a member constituting the lifting drive system of the lifting plate or a member contacting the lifting plate reaching the upper limit position due to driving of the lifting plate exceeding the upper limit position. It is useful as a sheet feeding device and an image processing device.

DESCRIPTION OF SYMBOLS 100 MFP 110 Document conveying device 154 Paper supply device 155 Pickup roller 161 Lift plate 162 Paper 163 Lift drive mechanism 164 Motor (drive unit)
204 Upper limit position sensor 401 Sensor state detection unit 402 Drive control unit

Claims (4)

An elevating plate attached to the seating surface so as to be movable up and down;
A drive unit for raising and lowering the elevating plate;
A pickup roller that is detachably provided above the elevating plate and feeds the sheet in contact with the upper surface of the sheet mounted on the mounting surface;
An upper limit position sensor which is a photosensor including a light emitting unit and a light receiving unit;
A light shielding plate comprising a locking portion and a light shielding portion;
The light-shielding portion is provided with a rotation shaft parallel to a drive shaft that rotationally drives the pickup roller, and the light-shielding plate rotates around the rotation shaft as the pickup roller moves up and down.
The locking portion is locked to the drive shaft that rotationally drives the pickup roller, and moves along with the vertical movement of the pickup roller,
Between the light emitting part and the light receiving part of the upper limit position sensor, the light shielding part is inserted and removed along with the vertical movement of the pickup roller,
In a state where the sheet bundle on the lifting plate and the pickup roller are separated from each other, the light shielding portion is inserted between the light emitting portion and the light receiving portion, and the upper limit position sensor is in a second detection state,
In a state where the sheet bundle on the lift plate and the pickup roller are in contact with each other, the light shielding portion is extracted from between the light emitting portion and the light receiving portion, and the upper limit position sensor is in the first detection state. ,
When the pickup roller is detached, the light shielding portion is extracted from between the light emitting portion and the light receiving portion, and the upper limit position sensor is in a first detection state,
A sensor state detector that detects whether or not the upper limit position sensor is capable of transitioning between the first detection state and the second detection state;
A drive control unit that permits ascending drive by the drive unit only when the upper limit position sensor is in the second detection state and the sensor state detection unit detects that the upper limit position sensor is capable of transition; and
A sheet supply apparatus comprising: When the sheet bundle on the lift plate and the pickup roller are separated from each other, the light shielding portion is inserted between the light emitting portion and the light receiving portion only by the weight of the pickup roller, and the upper limit position sensor The sheet supply apparatus according to claim 1, wherein the second detection state is set.   The sheet supply apparatus according to claim 2, wherein the sensor state detection unit detects whether or not the upper limit position sensor is capable of transition based on a drive current of the light emitting unit. An image processing apparatus comprising the sheet feeding apparatus according to claim 1.

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