JP2011006236A - Paper feeding device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the number of paper in a paper feeding device even in an electric power-saving mode.SOLUTION: A distance measuring sensor 41 for supplying electric power even in the electric power--saving mode, is arranged above a lifting plate 143. When the paper is replenished and inserted again into a paper feeding unit 19 by pulling out a paper feeding cassette 191 from the paper feeding unit 19, the distance measuring sensor 41 measures a distance up to the uppermost surface of a paper bundle S, to be output to a control part. The control part calculates the number of paper bundles S from a detected distance of the distance measuring sensor 41.

Description

  The present invention relates to a sheet feeding device that stores and feeds a sheet bundle, and an image forming apparatus including the sheet feeding device.

  A paper feeding device used for an image forming apparatus such as a copying machine, a facsimile machine, or a printer is configured to feed paper one by one from a bundle of paper stored in the paper feeding device. An image fed to an image forming unit in the forming apparatus and subjected to an image forming process is transferred.

  In such a sheet feeding device, the sheet bundle is generally placed on a lifting plate, and a pickup roller generally conveys the uppermost sheet of the sheet bundle one by one to the outside. Then, the motor ascends one end of the elevating plate so that the uppermost surface of the sheet bundle is always in contact with the pickup roller, whereby the entire elevating plate is inclined. That is, the inclination angle of the lifting plate changes depending on the remaining amount of the sheet bundle S. Using this configuration, Patent Document 1 describes a method of detecting the remaining amount of paper from the inclination angle of the lifting plate.

JP-A-10-274869

  However, in the method of Patent Document 1, the remaining amount of paper cannot be detected unless the lifting plate is lifted. In recent years, there are many image forming apparatuses provided with a normal mode and a power saving mode in which power consumption is reduced as compared with the normal mode. In the power saving mode, power is supplied to logic circuits such as control devices and sensors, but power supply to power circuits such as motors and motor drivers is stopped. Therefore, even if paper is supplied to the paper feeder in the power saving mode, the number of sheets in the paper feeder is not detected immediately, and the number of sheets can be detected after returning to the normal mode and the lifting plate is raised. Become. Therefore, the user cannot know the number of sheets during the power saving mode, and is inconvenienced.

  The present invention has been made to solve the above problems, and provides a paper feeding device and an image forming apparatus that can detect the number of sheets in the paper feeding device even in the power saving mode. It is the purpose.

  According to a first aspect of the present invention, there is provided a paper feeding device for storing a recording medium. The paper feeding device can be attached to and detached from the apparatus main body, and the recording medium stored in the housing means is fed one by one. Conveying means, and provided in the storage means, on which the recording medium is placed, and the retreat position closest to the bottom surface of the storage means and the top surface of the recording medium placed above are the conveying means An elevating means for elevating and lowering between the paper feed positions that are in contact with each other, a driving means for elevating the elevating means, and an elevating means disposed above the elevating means. Measuring means for measuring the distance to the uppermost surface of the recording medium placed on the lifting means, and using the distance to the uppermost surface of the recording medium measured by the measuring means, Calculate the number of recording media A normal number mode for supplying power to the sheet number calculating means, the conveying means, the driving means, the measuring means, and the number calculating means, and a power saving mode for supplying power to the measuring means and the number calculating means. Power control means for controlling power supply to each means, and in the normal mode, the drive means displaces the elevating means so that the elevating means is always located at the paper feeding position, and In the power mode, the elevating means is displaced to the retracted position.

  Conventionally, the number of sheets is obtained by detecting the amount of displacement (for example, angle) of the lifting / lowering means. In the power saving mode, power is not supplied to a power system circuit such as a motor that lifts the lifting / lowering means. Sometimes, when the sheet feeding device was detached and the amount of displacement of the elevating means became zero, the number of recording media could not be detected until the normal mode was restored and power was supplied to the motor to displace the elevating means.

  Therefore, even in the power saving mode, the measuring means that supplies power is arranged above the lifting and lowering means, and the number of recording media is calculated based on the measurement result. However, the number of recording media can be known, and the convenience of the paper feeding device can be improved.

  Here, “the retreat position closest to the bottom surface of the storage means” refers to a position where the elevating means is in the lowest position.

  According to a second aspect of the present invention, there is provided the paper feeding device according to the first aspect, wherein the elevating means is moved from the measuring means when the elevating means is in the retracted position and the recording medium is not placed. Distance storing means for storing the distance up to and a thickness storing means for storing the thickness per sheet of the recording medium in advance, wherein the number calculating means is stored in the distance storing means The quotient obtained by dividing the difference between the distance and the distance to the top surface of the recording medium measured by the measuring means by the thickness per sheet of the recording medium stored in the thickness storage means is mounted on the lifting means. It is calculated as the number of the recording media placed.

  According to this configuration, the number of sheets can be calculated in a simple process by storing in advance the distance from the measuring means to the lifting means and the thickness per recording medium when the lifting means has no recording medium and is in the retracted position. The means can calculate the number of recording media.

  According to a third aspect of the present invention, there is provided the sheet feeding device according to the first or second aspect, further comprising an initial number storage unit that stores the number of recording media calculated by the number calculation unit, and the driving unit After the displacement means is displaced to the paper feed position, the number calculation means counts the number of the recording media conveyed by the conveyance means, and the number of the recording media stored in the initial number storage means A value obtained by subtracting the counted number of transported recording media is calculated as the number of the recording media placed on the elevating means.

  “After the driving means displaces the elevating means to the paper feeding position” means in the normal mode. In other words, according to this configuration, after switching from the power saving mode to the normal mode, only by performing a calculation process of subtracting the number of transported sheets from the number of recording media calculated based on the measurement result of the measuring unit, The number of recording media in the paper feeder can be easily obtained.

  According to a fourth aspect of the present invention, there is provided the sheet feeding device according to the first or second aspect, wherein the angle detecting unit detects an inclination angle of the elevating unit, and the elevating / lowering unit is associated with the inclination angle of the elevating unit. Angle / initial number storage means for storing the number of the recording media placed on the means in advance, and after the drive means displaces the elevating means to the paper feeding position, the number calculation means comprises: The number of the corresponding storage medium is read from the angle / initial number storage means based on the inclination angle of the elevation means detected by the angle detection means, and the recording medium placed on the elevation means is read out. The number of sheets is determined.

  Similarly to the above, “after the driving means displaces the elevating means to the paper feeding position” refers to the normal mode. That is, according to this configuration, after switching from the power saving mode to the normal mode, the number of storage media is read from the angle / initial number storage unit based on the inclination angle of the lifting unit detected by the angle detection unit. The number of recording media placed on the lifting / lowering means can be determined, and the software processing load can be reduced.

  According to a fifth aspect of the present invention, in the paper feeding device according to any one of the first to fourth aspects, the image forming apparatus further includes a determination unit that determines the presence / absence of the recording medium placed on the lifting / lowering unit. The measuring means includes a light emitting element that emits light at a predetermined angle with respect to the opening, a light receiving element that receives reflected light of the light, and an arrival point of reflected light received by the light receiving element. And a calculation means for calculating a distance to the reflection position of the light emitted from the light emitting element by a triangulation method, and the lifting means is opened at a position where the emitted light of the measurement means is irradiated. And when the detection result of the measuring means is a distance measured to the lower part of the lifting means through the opening, the judging means judges that the recording medium is not in the lifting means. Is.

  According to this configuration, when there is no recording medium in the lifting / lowering means, the measuring means measures the distance passing through the opening and below the lifting / lowering means (for example, the bottom surface of the storage means). That is, the detection distance of the measuring means changes abruptly when the recording medium is placed on the lifting means and when it is not. Therefore, the determination unit can reliably detect the presence or absence of the recording medium.

  According to a sixth aspect of the present invention, there is provided an image forming apparatus according to any one of the first to fifth aspects, and an image forming unit that forms an image on a recording medium fed by the paper feeding apparatus. And comprising.

  According to this structure, there exists an effect similar to Claims 1-5.

  According to the present invention, the power-saving measuring means is arranged above the lifting / lowering means even in the power-saving mode, and the number of recording media is calculated based on the measurement result, thereby saving power. Even in the mode, the number of recording media can be known, and the convenience of the paper feeding device can be improved.

FIG. 2 is a side view schematically showing an internal configuration of the image forming apparatus. FIG. 3 is a cross-sectional view of a paper feed unit according to the first embodiment. The perspective view of a paper feed unit. 1 is a block diagram illustrating an electrical configuration of an image forming apparatus. 6 is a flowchart showing a flow of sheet number detection processing in the first embodiment. Sectional drawing of the paper feed unit in 2nd Embodiment. 9 is a flowchart showing a flow of sheet number detection processing in the second embodiment.

[First Embodiment]
Hereinafter, an image forming apparatus including a sheet feeding device according to a first embodiment will be described with reference to the drawings. FIG. 1 is a side view schematically showing an internal configuration of an image forming apparatus 1 including a paper feeding unit 19 which is a paper feeding device according to the present invention. The image forming apparatus 1 is a multifunction device having functions such as a copy function, a printer function, a scanner function, and a facsimile function. The image forming apparatus 1 includes a main body 2, a stack tray 3 disposed on the left side of the main body 2, and a main body. The document reading unit 4 is disposed above the unit 2, and the document feeding unit 5 is disposed above the document reading unit 4.

  An input operation unit 6 is provided on the front part of the image forming apparatus 1. The input operation unit 6 displays a start key 7 for a user to input a print execution instruction, a numeric keypad 8 for inputting the number of prints, and operation guide information for various copying operations. A display unit 9 composed of a liquid crystal display or the like having a touch panel function for input, a reset key 10 for resetting setting contents set on the display unit 9, and a stop for stopping a printing (image forming) operation being executed A key 11 and a function switching key 12 for switching between a copy function, a printer function, a scanner function, and a facsimile function are provided.

  The document reading unit 4 includes a scanner unit 13 including an image sensor such as a charge coupled device (CCD) sensor and a complementary metal oxide semiconductor (CMOS) sensor and an exposure lamp, a document table 14 formed of a transparent member such as glass, and the like. A document reading slit 15 is provided. The scanner unit 13 is configured to be movable by a driving unit (not shown). When reading a document placed on the document table 14, the scanner unit 13 is moved along the document surface at a position facing the document table 14 to scan the document. While acquiring the image data. When reading the document fed by the document feeding unit 5, the document is moved to a position facing the document reading slit 15 and synchronized with the document feeding operation by the document feeding unit 5 via the document reading slit 15. The image of the original is scanned to obtain image data.

  The document feeder 5 includes a document placement unit 16 for placing a document, a document discharge unit 17 for ejecting an image-read document, and a document placed on the document placement unit 16. A document transport mechanism 18 including a paper feed roller, a transport roller (not shown), and the like for feeding the paper one by one to a position facing the document reading slit 15 and discharging it to the document discharge section 17 is provided.

  Further, the document feeding unit 5 is provided so as to be rotatable with respect to the main body unit 2 so that the front side thereof can move upward. By moving the front side of the document feeder 5 upward to open the upper surface of the document table 14, the user can place a read document, for example, a book in a spread state, on the upper surface of the document table 14. ing.

  The main body 2 includes a plurality of paper feeding units 19, a pickup roller 20 that feeds the paper from the paper feeding unit 19 one by one and transports the paper to the image forming unit 21, and an image on the paper transported from the paper feeding unit 19. And an image forming unit 21 to be formed. Further, a distance measuring sensor 41 for measuring the distance to the uppermost surface of the sheet bundle stored in the sheet feeding unit 19 is arranged on the upper part of the sheet feeding unit 19.

  The image forming unit 21 outputs a laser beam or the like based on the image data acquired by the scanner unit 13 to expose the photosensitive drum 22, and forms an electrostatic latent image on the surface of the photosensitive drum 22. A developing unit 24 that forms a toner image by attaching toner to the surface of the photosensitive drum 22 on which the electrostatic latent image is formed; a transfer unit 25 that transfers the toner image on the photosensitive drum 22 to a sheet; A fixing device 28 having a fixing roller 26 and a pressure roller 27 for fixing the toner image to the paper by heating the paper on which the toner image has been transferred, and a paper conveying path in the image forming unit 21. A pair of conveyance rollers 30 and 31 for conveying the stack tray 3 or the discharge tray 29 is provided.

  When images are formed on both sides of a sheet, the image forming unit 21 forms an image on one side of the sheet, and then the sheet is nipped between the pair of transport rollers 30 on the discharge tray 29 side. In this state, the conveyance roller pair 30 is reversed to switch back the sheet, and the sheet is sent to the sheet conveyance path 32 to be conveyed again to the upstream area of the image forming unit 21. The image forming unit 21 forms an image on the other surface. After that, the paper is discharged to the stack tray 3 or the discharge tray 29.

  In addition, the image forming apparatus 1 includes a normal mode and a power saving mode in which power consumption is reduced compared to the normal mode. The normal mode is a mode in which power is supplied to all circuits constituting the image forming apparatus 1 such as logic circuits such as a control device and sensors and power circuits such as a motor and a motor driver. The power saving mode is a mode in which power is supplied to the logic circuit, but power consumption to the power circuit is stopped, thereby reducing power consumption compared to the normal mode.

  FIG. 2 is a schematic cross-sectional view showing an example of the paper feeding unit 19 in the present embodiment. FIG. 2A shows a state in which the elevating plate 143 is raised and is in the paper feeding position, and FIG. It is the figure which showed when the board 143 exists in a retracted position. Here, the paper feeding position is a position where the elevating plate 143 is raised and the upper surface of the sheet bundle S placed on the elevating plate 143 comes into contact with the pickup roller 20 and can be fed. The retreat position is a position when the elevating plate 143 is lowered to the lowest position. First, the sheet feeding unit 19 will be described with reference to FIG.

  The paper feeding unit 19 includes a paper feeding cassette 191 that can be attached to and detached from the paper feeding unit 19, a lifting plate 143 that is rotatable around a fulcrum 144, and a lift arm 145 that changes the inclination angle of the lifting plate 143. I have. The lift arm 145 has its tip raised and lowered by the rotation of the support shaft 146 driven by the lift motor 148. The elevating plate 143 and the lift arm 145 are provided in the paper feed cassette 191.

  A motor side gear 149 is concentrically fixed to the drive shaft of the lift motor 148, while a support shaft 146 integrated with the lift arm 145 is supported by a support shaft that meshes with the motor side gear 149 through a coupling (not shown). 146 and a lift gear 147 integrated with each other, and forward / reverse driving of the lift motor 148 is transmitted to the lift plate 143 via the motor side gear 149, the lift gear 147, the support shaft 146, and the lift arm 145, and the lift plate 143 rotates around the fulcrum 144. It is designed to rotate forward and backward. Note that the drive control of the lift motor 148 is performed by a control unit described later.

  In addition, a pickup roller 20 is provided at a sheet feeding position directly above the tip of the lifting plate 143 in each sheet feeding unit 19, and the most of the sheet bundle S placed on the lifting plate 143 by the rotation of the pickup roller 20. The upper sheet P is fed out toward the sheet conveyance path 32. The lift motor 148 then tilts the lifting plate 143 so that the uppermost surface of the sheet bundle S is brought into contact with the pickup roller 20 when the paper P placed on the lifting plate 143 is drawn out and reduced. The motor side gear 149 is rotated so as to increase gradually. Accordingly, the sheet bundle S placed on the elevating plate 143 is always in contact with the pickup roller 20 so that the uppermost sheet P of the sheet bundle S is always picked up regardless of the decrease in the number of sheets. The roller 20 can be fed out.

  When the image forming apparatus 1 is in the normal mode, as shown in FIG. 2A, the lift motor 148 causes the uppermost surface of the sheet bundle S placed on the elevating plate 143 to always contact the pickup roller 20. By rotating the motor side gear 149, the inclination angle of the elevating plate 143 is gradually increased. In the power saving mode, the power supply to the lift motor 148 is stopped, so that the lift gear 147 remains locked when the mode is switched from the normal mode to the power saving mode. That is, the lifting plate 143 is also held at the tilt angle when switched to the power saving mode.

  However, when the paper feed cassette 191 is pulled out from the paper feed unit 19, the lift gear 147 is unlocked and the lift arm 145 receives the weight of the lift plate 143 as shown in FIG. At the same time, the elevating plate 143 is also lowered and returned to the retracted position. Then, even if paper is supplied into the paper feed cassette 191 and the paper feed cassette 191 is inserted into the paper feed unit 19 again, power is not supplied to the lift motor 148 during the power saving mode, so that the lifting plate 143 is shown in FIG. It remains in the retracted position shown in (b).

  Thereafter, when the mode is switched from the power saving mode to the normal mode, power is supplied to the lift motor 148 until the uppermost surface of the sheet bundle S placed on the lifting plate 143 comes to a position in contact with the pickup roller 20. The lift motor 148 rotates the motor side gear 149 so that 143 is lifted.

  As described above, when the lift motor 148 is driven to lift the lifting plate 143 so that the uppermost surface of the sheet bundle S is always in contact with the pickup roller 20, the entire lifting plate 143 is inclined. That is, since the inclination angle of the lifting plate 143 changes depending on the remaining amount of the sheet bundle S, conventionally, the number of the sheet bundle S is detected from the angle of the lifting plate 143.

  However, when the paper feed cassette 191 is detached from the paper feed unit 19, the lift plate 143 returns to the retracted position as shown in FIG. Even if the paper is supplied to the paper feed cassette 191 and attached to the paper feed unit 19 again, the power supply to the power circuit is stopped when the power is in the power saving mode at the time of attachment, so the lift motor 148 Does not work. That is, since the lifting plate 143 remains in the retracted position and does not rise to the paper feeding position, if the paper cassette 191 is pulled out and replenished with paper in the power saving mode, the number of sheets cannot be detected until the normal mode is restored. was there.

  Therefore, the number of sheets in the sheet bundle S is detected by using the distance measuring sensor 41 connected to the power supply system that is always energized even in the power saving mode. The distance measuring sensor 41 is disposed above the elevating unit 143, measures the distance to the uppermost surface of the sheet bundle S when the elevating plate 143 is in the retracted position, and outputs the detected distance to the control unit described later. The control unit calculates the number of sheet bundles S using the detection distance of the distance measuring sensor 41. By doing so, the number of the sheet bundle S can be detected even if the sheet feeding cassette 191 is pulled out from the sheet feeding unit 19 and the sheets are replenished during the power saving mode, and the convenience of the image forming apparatus 1 is improved. Can do.

  FIG. 3 is a schematic perspective view of the paper feed cassette 191. In addition to the lifting plate 143 and the lift arm 145, the paper feed cassette 191 includes a width alignment cursor pair 44a and 44b for positioning the stored paper bundle S in the width direction, and a rear end cursor for aligning the rear end of the paper bundle S. 43. The width alignment cursor pairs 44a and 44b are provided so as to be reciprocally movable along the guide rail in the sheet width direction (the direction of arrow A in FIG. 3). Further, since the paper P is sent out in the direction of arrow B, the rear end cursor 43 is provided so as to be reciprocally movable along the guide rail in parallel with the sheet conveying direction (in the direction of arrow B in FIG. 3). The sheet bundle S can be stored at a predetermined position in the sheet feeding cassette 191 by moving the width alignment cursor pairs 44a and 44b and the rear end cursor 43 according to the size of the stored sheet.

  Further, the elevating plate 143 has an opening 42 at the irradiation position of the emitted light of the distance measuring sensor 41. The distance measuring sensor 41 measures the distance to the uppermost surface of the sheet bundle S when the sheet bundle S is placed on the lifting plate 143. By providing this opening 42, the distance measuring sensor 41 measures the sheet on the lifting plate 143. When there is not, the distance measuring sensor 41 measures the distance to the lower part of the lifting plate 143 (the bottom part of the paper feed cassette 191) through the opening 42. For example, the distance measured by the distance measuring sensor 41 when there is no sheet on the lifting plate 143 and is in the retracted position is measured in advance and stored in the storage unit or the like. After that, when the detection distance of the distance measuring sensor 41 is equal to the stored distance, it indicates that the distance measuring sensor 41 has measured the distance to the lower side of the lifting plate 143 through the opening 42, and therefore the paper is out. It can be determined with certainty.

  In addition, by providing the opening 42, the detection distance of the distance measuring sensor 41 changes abruptly when the recording medium is placed on the lifting plate 143 and when it is not. Alternatively, the reflected light of the light emitted from the distance measuring sensor 41 may not enter the distance measuring sensor 41. Using this characteristic, when the detection distance of the distance measuring sensor 41 is equal to or greater than a predetermined distance, or when measurement is not possible, it may be determined that the sheet is out of paper.

  The distance measuring sensor 41 and the opening 42 are arranged so that the lift arm 145 is not located in the measurement range of the distance measuring sensor 41 so that the light emitted from the distance measuring sensor 41 does not pass through the opening 42 and be reflected by the lift arm 145. It is desirable to arrange.

  FIG. 4 is a block diagram showing an electrical configuration of the image forming apparatus 1. The image forming apparatus 1 includes a control unit 91, a storage unit 92, a document reading unit 4, an image memory 93, an image processing unit 94, an image forming unit 21, a paper feeding unit 19, an input operation unit 6, and a network I / F unit 96. It is prepared for. In addition, the same code | symbol is attached | subjected to the same component demonstrated using FIG. 1 and 2, and description is abbreviate | omitted. In addition, the constituent elements indicated by the dotted lines are necessary elements in the second embodiment, and thus will not be described in the present embodiment.

  The storage unit 92 stores programs, data, and the like for realizing various functions provided in the image forming apparatus 1, and further functions as a distance storage unit 921 and a sheet thickness storage unit 922. The distance storage unit 921 stores in advance the distance from the distance measuring sensor 41 to the lifting plate 143 when the sheet is not placed on the lifting plate 143 and is in the retracted position. The sheet thickness storage unit 922 stores in advance a thickness per sheet P (corresponding to a thickness t described later). The paper thickness storage unit 913 may store the thickness corresponding to the paper manufacturer, the product number of the paper, and the like. In this case, the user inputs the manufacturer and the product number of the paper P to be used. 5, the control unit 91 reads the corresponding thickness from the sheet thickness storage unit 922 based on the input information. Furthermore, the thickness of the paper P directly input from the input operation unit 5 by the user may be stored in the paper thickness storage unit 922.

  The image memory 93 temporarily stores image data acquired by the document reading unit 4 and image data transmitted from an external apparatus via the network I / F unit 96. The image processing unit 94 performs image processing such as image correction and enlargement / reduction on the image data stored in the image memory 93.

  The paper feed unit 19 includes a distance measuring sensor 41 and a cassette detection sensor 42. The cassette detection sensor 42 is a sensor that detects whether or not the paper feed cassette 191 is attached to the paper feed unit 19. When the cassette detection sensor 42 detects the attachment of the paper feed cassette 191, it outputs a detection signal to the control unit 91.

  The network I / F unit 96 includes a communication module such as a LAN board, and transmits / receives various data to / from an external device via a network (not shown) connected to the network I / F unit 96.

  The control unit 91 is configured by a CPU (Central Processing Unit) and the like, reads a program stored in the storage unit 92 and executes processing, and outputs an instruction signal to each functional unit, data transfer, and the like. The image forming apparatus 1 is comprehensively controlled to have a sheet number calculation unit 911, a sheet number storage unit 912, and a power supply control unit 913.

  The sheet count calculation unit 911 is measured by the distance measuring sensor 41 when the paper feed cassette 19 is pulled out from the main body 2 and replenished with paper in the power saving mode and the paper feed cassette 19 is inserted into the main body 2 again. The initial number of sheet bundles S placed on the lifting plate 143 is calculated using the detected distance. When the paper P is transported from the paper feed cassette 19 and printing is started in the normal mode, the paper number calculation unit 911 counts the number of printed sheets and calculates the number of sheets by subtracting the number of printed sheets from the initial number. .

  Although not shown, a sensor for detecting the presence or absence of the paper feed cassette 19 in the main body unit 2 is disposed in the main body unit 2, and the control unit 91 controls the paper feed based on a signal output from this sensor. The attachment / detachment status of the cassette 19 can be grasped. The sensor for detecting the presence or absence of the paper feed cassette 19 is supplied with power even in the power saving mode.

  An example of a method for calculating the initial number of sheets S will be briefly described with reference to FIG. First, the detection distance H of the distance measuring sensor 41 when there is no paper on the elevating plate 143 before factory shipment of the image forming apparatus 1 is measured in advance and stored in the storage unit 92 or the like. When the paper feed cassette 19 is pulled out from the main body 2 and inserted again, the distance measuring sensor 41 measures the distance to the uppermost surface of the sheet bundle S. The distance to the top surface of the sheet bundle S measured at this time is y.

  The sheet number calculation unit 911 calculates the thickness of the sheet bundle S by subtracting the distance y from the distance H (T = H−y), and divides the thickness T by the thickness t per sheet P, The number n of sheet bundles S can be obtained (n = T / t).

  The sheet number storage unit 912 stores the initial number calculated by the sheet number calculation unit 911, and updates and stores the sheet number calculated by the sheet number calculation unit 911 when printing is started. When a transmission request for the number of sheets is received from a personal computer or the like connected to the image forming apparatus 1 via the network I / F 96, the control unit 91 transmits the number of sheets stored in the sheet number storage unit 912 to the personal computer. . In this way, the user can check the number of sheets while being far away from the image forming apparatus 1.

  The power supply control unit 913 controls power supply to each component in the normal mode and the power saving mode. Specifically, the power supply control unit 913 supplies power to all electric systems in the normal mode, and supplies power to power system circuits (the lift motor 148, the image forming unit 21, and the like) in the power saving mode. It stops, and it controls to supply electric power only to a logic system circuit (the control part 91, the ranging sensor 41, the memory | storage part 92, etc.).

  FIG. 5 is a flowchart showing the flow of the sheet number detection process in the present embodiment. When a detection signal indicating that the paper feed cassette 191 is mounted is output from the cassette detection sensor 42 (step S11; YES), the control unit 91 is a distance from the distance measurement sensor 41 to the uppermost surface of the sheet bundle S. y is measured (step S12). At this time, the elevating plate 143 is in the retracted position. Then, the sheet number calculation unit 911 calculates the initial number of the sheet bundle S using the detection distance of the distance measuring sensor 41, and the sheet number storage unit 912 stores the initial number (step S13).

  If it is the normal mode (step S14; YES), the controller 91 drives the lift motor 148 to move the lift plate 143 to the paper feed position (step S15). If it is in the power saving mode (step S14; NO), the determination process of step S14 is repeated until the mode is switched to the normal mode. During this time, when the power saving mode is switched to the normal mode, the power supply control unit 913 starts supplying power to the power system circuits (the lift motor 148, the image forming unit 21, and the like).

  Next, when printing is started (step S16; YES), the sheet number calculation unit 911 starts counting the number of printed sheets (step S17), and during printing, the control unit 91 detects that the distance detected by the distance measuring sensor 41 is a distance. It is determined whether or not the lifting plate 143 stored in the storage unit 921 is equal to the distance H when there is no sheet (step S18). If the detected distance is equal to the distance H (step S18; YES), the control unit 91 determines that there is no paper, displays a warning message on the display unit 9 (step S19), and shifts the processing to step S11.

  If the detection distance of the distance measuring sensor 41 is not equal to the distance H during printing (step S18; NO, step S20; YES), the sheet number calculation unit 911 stores the initial number stored in the sheet number storage unit 912. The number of printed sheets is subtracted from the calculated number of sheets after printing (step S21). As a method for calculating the number of sheets, the sheet number calculation unit 911 may subtract 1 from the value of the initial number every time one sheet is printed.

  The sheet number storage unit 912 updates and stores the printed sheet number calculated by the sheet number calculation unit 911 as an initial number (step S22). When the power supply is not turned off (step S23; NO), and the paper feed cassette 191 is pulled out from the paper feed unit 19 (step S24; YES), the control unit 91 shifts the process to step S11. When the paper feed cassette 191 has not been pulled out (step S24; NO), the control unit 91 shifts the process to step S16. When the power is turned off (step S23; YES), the control unit 91 ends the process.

  Thus, when the lift plate 143 is in the retracted position (steps S11 to S14 in FIG. 5; corresponding to immediately after the paper feed cassette 191 is mounted in the power saving mode or the normal mode), the measurement distance of the distance measuring sensor 41 is measured. Is used to detect the number of sheets S, and the sheet number storage unit 912 stores this as the initial number. When the elevating plate 143 is at the paper feed position (steps S16 to S22 in FIG. 5, particularly during printing in the normal mode), the number of sheets S is calculated by subtracting the number of printed sheets from the initial number. .

  Conventionally, the angle of the lifting plate 143 is detected to obtain the number of sheets. In the power saving mode, power is not supplied to the motor 148 that lifts the lifting plate 143. The number of sheets could not be detected until the normal mode was restored. Therefore, as described above, the sheet feeding cassette 191 is attached and detached during the power saving mode by detecting the number of sheets S using the distance measuring sensor 41 to which power is always supplied even in the power saving mode. However, the number of sheets S can be detected, and the convenience of the image forming apparatus 1 can be improved.

[Second Embodiment]
In the first embodiment, the method of always calculating the number of sheets S using the distance measuring sensor 41 has been described. In the present embodiment, a method for obtaining the number of sheets from the inclination angle of the distance measuring sensor 41 and the lifting plate 143 will be described. Since most of the mechanical configuration and electrical configuration of the image forming apparatus according to the present embodiment are the same as those of the image forming apparatus 1 described in the first embodiment, the same components are denoted by the same reference numerals. In addition, description is abbreviate | omitted and only a different part is demonstrated.

  FIG. 6 is a schematic cross-sectional view showing an example of the paper feed cassette 191 in the present embodiment. A rotary encoder 50 is concentrically fixed to a fulcrum 144 of the elevating plate 143, and a rotation angle of the fulcrum 144, that is, an inclination angle of the elevating plate 143 is detected by the rotary encoder 50.

  Here, the tilt angle of the lift plate 143 decreases as the number of the sheet bundles S placed on the lift plate 143 increases, and the tilt angle of the lift plate 143 increases as the number decreases. Therefore, the inclination angle of the elevating plate 143 detected by the rotary encoder 50 represents the number of the sheet bundles S placed on the elevating plate 143.

  In the method for calculating the number of sheets by the distance measuring sensor 41 described in the first embodiment, an error occurs in the calculation result as the number of sheets S decreases. This is caused by the accuracy of the detection distance of the distance measuring sensor 41, the variation in the thickness t per sheet P, and the like. In addition, the paper number calculation unit 911 counts the number of printed sheets during printing, and after printing, it is necessary to calculate the number of sheets, which places a processing load.

  Thus, in the present embodiment, the number of sheets S is detected using the detection distance of the distance measuring sensor 41 in the power saving mode, and the number of sheets is detected using the detection angle of the rotary encoder 50 in the normal mode. Thus, a method for reducing the processing load of the control unit 91 will be described.

  The electrical configuration of the image forming apparatus 1 in the present embodiment will be described with reference to FIG. The block diagram showing the electrical configuration of the image forming apparatus 1 of the present embodiment is obtained by adding the elements indicated by the dotted lines in FIG.

  The storage unit 92 stores a detection angle / number table 923. The detected angle / sheet number table 923 is a correspondence table in which the detected angle and the number of sheets are stored in association with each other. For example, when the detection angle = θ1, the number of sheets = m1, and when the detection angle = θ2, the number of sheets = m2, and the number of sheets corresponding to the detection angle is checked in advance and a table is created. Remembered.

  In the normal mode, the control unit 91 reads the corresponding sheet number from the detection angle / sheet number table 923 based on the detection angle output from the rotary encoder 50 to obtain the sheet number. That is, in the normal mode, the sheet number calculation unit 911 does not need to count the number of printed sheets or calculate the number of sheets, and can reduce the processing load.

  FIG. 7 is a flowchart showing the flow of the number of sheets detection process of the sheet feeding unit 19 in the present embodiment. When a detection signal indicating that the paper feed cassette 191 is mounted is output from the cassette detection sensor 42 (step S11; YES), the control unit 91 is a distance from the distance measurement sensor 41 to the uppermost surface of the sheet bundle S. y is measured (step S12). At this time, the elevating plate 143 is in the retracted position. Then, the sheet number calculation unit 911 calculates the initial number of the sheet bundle S using the detection distance of the distance measuring sensor 41, and the sheet number storage unit 912 stores the initial number (step S13).

  If it is the normal mode (step S14; YES), the controller 91 drives the lift motor 148 to move the lift plate 143 to the paper feed position (step S15). If it is in the power saving mode (step S14; NO), the determination process of step S14 is repeated until the mode is switched to the normal mode. During this time, when the power saving mode is switched to the normal mode, the power supply control unit 913 starts supplying power to the power system circuits (the lift motor 148, the image forming unit 21, and the like).

  Next, when printing is started (step S <b> 16; YES), during printing, the control unit 91 determines whether or not the detection distance of the distance measuring sensor 41 is equal to the distance H when there is no paper on the lifting plate 143. (Step S18). When the detected distance is equal to the distance H stored in the distance storage unit 921 (step S18; YES), the control unit 91 determines that there is no paper, and displays a warning message on the display unit 9 (step S19). The process proceeds to S11.

  If the detection distance of the distance measuring sensor 41 is not equal to the distance H during printing (step S18; NO, step S20; YES), the control unit 91 detects the detection angle based on the detection angle output from the rotary encoder 50. / The number of sheets is read from the number-of-sheets table 923 to obtain the number of sheets (step S31). Then, the sheet number storage unit 912 updates and stores the sheet number read from the detection angle / sheet number table 923 by the control unit 91 as an initial number (step S22).

  When the power supply is not turned off (step S23; NO), and the paper feed cassette 191 is pulled out from the paper feed unit 19 (step S24; YES), the control unit 91 shifts the process to step S11. If the paper feed cassette 19 has not been pulled out (step S24; NO), the controller 91 proceeds to step S16. When the power is turned off (step S23; YES), the control unit 91 ends the process.

  As described above, when the lifting plate 143 is in the retracted position (steps S11 to S14 in FIG. 7, which corresponds to immediately after the sheet feeding cassette 191 is mounted in the power saving mode or the normal mode), the measurement by the distance measuring sensor 41 is performed. The number of sheets S is detected using the distance, and the sheet number storage unit 912 stores this as the initial number. When the elevating plate 143 is in the paper feed position (steps S16 to S22 in FIG. 7, particularly during printing in the normal mode), the rotary encoder 50 detects the angle of the elevating plate 143 to detect the sheet bundle S. Detect the number of sheets.

  As described above, the number of sheets S is detected using the detection distance of the distance measuring sensor 41 when the paper feed cassette 191 is mounted, and the number of sheets is detected using the detection angle of the rotary encoder 50 in the normal mode. By doing so, the processing load for calculating the number of sheets after printing by the control unit 91 can be reduced.

1 Image forming apparatus 143 Lift plate (lifting means)
144 Support point 145 Lift arm 146 Support shaft 147 Lift gear 148 Lift motor (drive means)
149 Motor side gear 19 Paper feeding unit (paper feeding device)
191 Paper cassette (storage means)
20 Pickup roller (conveying means)
41 Ranging sensor (measuring means)
42 Opening 42 Cassette detection sensor 50 Rotary encoder (angle detection means)
6 Input operation unit 9 Display unit 91 Control unit (drive control means, determination means)
911 Number of sheets calculation section (number calculation means)
912 Paper number storage unit (initial number storage means)
913 Power supply control unit (power control means)
92 Storage Unit 921 Distance Storage Unit (Distance Storage Unit)
922 Paper thickness storage unit (thickness storage means)
923 Detection angle / number of sheets table (angle / initial number of sheets storage means)
93 Image memory 94 Image processing unit 96 Network I / F unit

Claims (6)

A storage means for storing a recording medium;
Conveying means for feeding and conveying the recording medium stored in the storage means one by one;
It is provided in the storage means and places the recording medium. The retracted position closest to the bottom surface of the storage means and the position where the uppermost surface of the recording medium placed above contacts the transport means. Elevating means for elevating between certain paper feed positions;
Drive means for raising and lowering the elevating means;
Measuring means disposed above the elevating means and measuring the distance to the top surface of the recording medium placed on the elevating means when the elevating means is in the retracted position;
A number calculating means for calculating the number of the recording media placed on the elevating means using the distance to the top surface of the recording medium measured by the measuring means;
Power supply to each means has a normal mode for supplying power to the transport means, the drive means, the measuring means, and the number calculating means, and a power saving mode for supplying power to the measuring means and the number calculating means Power control means for controlling
In the normal mode, the driving means displaces the lifting means so that the lifting means is always located at the paper feeding position, and in the power saving mode, the lifting means is displaced to the retracted position. Is a paper feeder. Distance storage means for preliminarily storing a distance from the measurement means to the lifting means when the lifting means is in the retracted position and the recording medium is not placed;
A thickness storage means for storing in advance the thickness per sheet of the recording medium;
Further comprising
The number calculating means is a sheet of the recording medium stored in the thickness storage means that is the difference between the distance stored in the distance storage means and the distance measured by the measuring means to the top surface of the recording medium. The paper feeding device according to claim 1, wherein a quotient divided by a hit thickness is calculated as the number of the recording media placed on the elevating means. An initial number storage means for storing the number of recording media calculated by the number calculation means;
After the driving means displaces the lifting / lowering means to the paper feeding position, the number calculating means counts the number of the recording media conveyed by the conveying means and stores the recording stored in the initial number storing means. The paper feeding device according to claim 1 or 2, wherein a value obtained by subtracting the counted number of transported recording media from the number of media is calculated as the number of the recording media placed on the elevating means. An angle detecting means for detecting an inclination angle of the elevating means;
Pre-angle / initial number storage means for storing the number of recording media placed on the lifting means in association with the inclination angle of the lifting means;
And after the driving means displaces the lifting / lowering means to the paper feeding position, the number calculating means is configured to determine the angle / initial number of sheets based on an inclination angle of the lifting / lowering means detected by the angle detecting means. The sheet feeding device according to claim 1 or 2, wherein the number of the corresponding storage medium is read from a storage means to determine the number of the recording media placed on the lifting / lowering means. A judgment means for judging the presence or absence of the recording medium placed on the lifting means;
The measuring means includes
A light emitting element that emits light at a predetermined angle with respect to the opening;
A light receiving element that receives reflected light of the light;
Based on the arrival point of the reflected light received by the light receiving element, calculation means for calculating the distance to the reflection position of the light emitted by the light emitting element by a triangulation method,
Having
The elevating means has an opening at a position where the emitted light of the measuring means is irradiated,
The determination means determines that there is no recording medium in the elevation means when the detection result of the measurement means is a distance measured to the lower side of the elevation means through the opening. The sheet feeding device according to any one of 4. A paper feeding device according to any one of claims 1 to 5,
Image forming means for forming an image on a recording medium fed by the paper feeding device;
An image forming apparatus.

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