JP6278244B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  In general, an image forming apparatus such as a printer or a multifunction peripheral feeds and conveys sheets stacked in a sheet feeding cassette and forms an image on the sheets.

  Some image forming apparatuses have a remaining sheet sensor that detects the remaining amount of sheets in the sheet cassette (see, for example, Patent Document 1).

JP-A-8-230286

  An image forming apparatus has an open / close sensor that detects the open / close state of the paper cassette separately from the paper remaining amount sensor, and starts printing when the open / close sensor determines that the paper cassette is open. Instead, the open / close sensor notifies that the paper feed cassette is open.

  On the other hand, it is conceivable to use the remaining paper sensor as an open / close sensor. For example, the remaining amount of paper is configured such that the output value when the paper cassette is open is the same as the output value when the paper is out. When a sensor is used, it is difficult to accurately detect that the paper feed cassette is in the open state with the paper remaining amount sensor.

  The present invention has been made in view of the above problems, and can accurately detect that a paper feed cassette is in an open state by a paper remaining amount sensor without separately providing an open / close sensor for the paper feed cassette. It is an object of the present invention to obtain an image forming apparatus that can be used.

  An image forming apparatus according to the present invention shows one or a plurality of paper feed cassettes, a paper remaining amount sensor for detecting a remaining amount of paper in the paper feed cassette, and a remaining amount of paper detected by the remaining paper amount sensor. A storage device for storing the remaining amount of paper and a remaining amount of paper indicating the remaining amount of paper detected by the remaining amount of paper sensor are acquired, and the remaining amount of paper detected by the remaining amount of paper sensor If not, the remaining paper amount value detected by the remaining sheet amount sensor and the remaining sheet amount sensor that updates the remaining sheet amount value stored in the storage device with the acquired remaining sheet amount value. Includes a cassette open / close determining unit that determines that the paper feed cassette is open when the remaining sheet value stored in the storage device is greater than a predetermined threshold value.

  According to the present invention, it is possible to accurately detect that the paper feed cassette is in the open state with the paper remaining amount sensor without separately providing a paper feed cassette open / close sensor.

FIG. 1 is a side view showing a part of a mechanical internal configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram showing a part of the electrical configuration of the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a flowchart for explaining the operation of the image forming apparatus according to the first embodiment. FIG. 4 is a flowchart for explaining the operation of the image forming apparatus according to the second embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.

  FIG. 1 is a side view showing a part of a mechanical internal configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus shown in FIG. 1 is an apparatus having an electrophotographic printing function, such as a printer, a facsimile machine, a copying machine, or a multifunction machine.

  The image forming apparatus of this embodiment has a tandem color developing device. The color developing device includes photosensitive drums 1a to 1d, exposure devices 2a to 2d, and developing units 3a to 3d. The photoconductor drums 1a to 1d are four-color photoconductors of cyan, magenta, yellow, and black. The photosensitive drums 1a to 1d are made of amorphous silicon, for example.

  The exposure devices 2a to 2d are devices that form electrostatic latent images by irradiating the photosensitive drums 1a to 1d with laser light while scanning. The laser beam is scanned in a direction (main scanning direction) perpendicular to the rotation direction (sub-scanning direction) of the photosensitive drums 1a to 1d. The exposure apparatuses 2a to 2d have a laser scanning unit including a laser diode that is a light source of laser light and an optical element (lens, mirror, polygon mirror, etc.) that guides the laser light to the photosensitive drums 1a to 1d.

  Further, around the photosensitive drums 1a to 1d, a charger such as a scorotron, a cleaning device, a static eliminator and the like are arranged. The cleaning device removes residual toner on the photosensitive drums 1a to 1d after the primary transfer, and the static eliminator neutralizes the photosensitive drums 1a to 1d after the primary transfer.

  The developing units 3a to 3d attach the toner cartridge filled with toners of four colors of cyan, magenta, yellow and black, and the toner conveyed from the toner hopper in the toner cartridge to the photosensitive drums 1a to 1d. A developing unit, and the toner is attached to the electrostatic latent images on the photosensitive drums 1a to 1d to form a toner image. The toner is transported from the toner hopper to the developing device by a toner transport unit that is operated by a driving device such as a motor (not shown).

  The photosensitive drum 1a, the exposure device 2a, and the developing unit 3a develop magenta, and the photosensitive drum 1b, the exposure device 2b, and the developing unit 3b develop cyan, the photosensitive drum 1c, and the exposure device 2c. The developing unit 3c performs yellow development, and the photosensitive drum 1d, the exposure device 2d, and the developing unit 3d perform black development.

  The intermediate transfer belt 4 is an annular image carrier (intermediate transfer member) that comes into contact with the photosensitive drums 1a to 1d and primarily transfers the toner images on the photosensitive drums 1a to 1d. The intermediate transfer belt 4 is stretched around the driving roller 5 and circulates in the direction from the contact position with the photosensitive drum 1d to the contact position with the photosensitive drum 1a by the driving force from the driving roller 5.

  As will be described later, the transfer roller 6 brings the conveyed paper into contact with the intermediate transfer belt 4 and secondarily transfers the toner image on the intermediate transfer belt 4 to the paper. The sheet on which the toner image has been transferred is conveyed to the fixing device 9 and the toner image is fixed on the sheet.

  The roller 7 has a cleaning brush, and the cleaning brush is brought into contact with the intermediate transfer belt 4 to remove the toner remaining on the intermediate transfer belt 4 after the transfer of the toner image onto the paper or after calibration.

  The sensor 8 irradiates the intermediate transfer belt 4 with a light beam, and detects reflected light from the surface of the intermediate transfer belt 4 or a toner pattern on the surface. For example, the sensor 8 irradiates a predetermined region of the intermediate transfer belt 4 (region to which the calibration toner patch is transferred) and detects the reflected light of the light beam at the time of toner gradation calibration, An electrical signal corresponding to the amount of light is output.

  Further, the image forming apparatus according to this embodiment includes a plurality of paper feed cassettes 11 and 12 and a manual feed tray 13.

  The paper feed cassette 11 can be opened and closed. When the paper cassette 11 is open, the paper cassette 11 is loaded with one or a plurality of papers 101 of a certain size, and in the closed state, the paper 101 is pushed upward by the lift plate 21. The sheet is brought into contact with the sheet feeding roller 22. The drive mechanism of the lift plate 21 is configured to mechanically push the lift plate 21 upward when the paper feed cassette 11 is in a closed state, for example. The sheets 101 placed in the sheet feeding cassette 11 are fed one by one from the upper side by the sheet feeding roller 22. The transport roller 23 is a roller for transporting the sheets 101 fed from the sheet feed cassette 11 by the sheet feed roller 22 one by one.

  Similarly, the paper feed cassette 12 can be opened and closed. When the paper cassette 12 is open, the paper cassette 12 is loaded with one or more sheets 102 of a certain size supplied by a user or the like. And is brought into contact with the paper feed roller 25. The drive mechanism of the lift plate 24 is configured to mechanically push up the lift plate 24 upward when the paper feed cassette 12 is in a closed state, for example. The sheets 102 placed in the sheet cassette 12 are fed one by one by the sheet feed roller 25 from the upper side. The transport roller 26 is a roller for transporting the sheets 102 fed from the sheet cassette 12 by the sheet feed roller 25 one by one.

  Further, a sheet is placed on the manual feed tray 13 by the user. The sheets placed on the manual feed tray 13 are fed one by one by the sheet feeding roller 27. The transport roller 28 is a roller that transports the paper fed from the manual feed tray 13 by the paper feed roller 27 one by one.

  The transport roller 29 is a transport roller on a transport path common to the paper 101 transported from the paper feed cassette 11 and the paper 102 transported from the paper feed cassette 12.

  The conveyance roller 30 is a conveyance roller on a conveyance path common to the sheets 101 and 102 conveyed from the paper feed cassettes 11 and 12 and the sheet conveyed from the manual feed tray 13.

  That is, when the paper feed cassette 11 is designated as the paper feed source at the time of printing, the paper 101 is transported by the transport rollers 23, 29, and 30 to a registration roller (not shown) in front of the transfer roller 6.

  When the paper feed cassette 12 is designated as the paper feed source at the time of printing, the paper 102 is transported by the transport rollers 26, 29, 30 to a registration roller (not shown) in front of the transfer roller 6.

  When the manual feed tray 13 is designated as a paper supply source at the time of printing, the paper is transported by the transport rollers 28 and 30 to a registration roller (not shown) in front of the transfer roller 6.

  Further, a paper remaining amount sensor 31 that detects the remaining amount of the paper 101 in the paper feeding cassette 11 is provided corresponding to the paper feeding cassette 11. Similarly, a paper remaining amount sensor 32 for detecting the remaining amount of the paper 102 in the paper feeding cassette 12 is provided corresponding to the paper feeding cassette 12. In this embodiment, the remaining paper amount sensors 31 and 32 have a configuration in which the output value when the paper feed cassettes 11 and 12 are in the open state is the same as the output value when the paper is out.

  The remaining sheet sensors 31, 32 are distance sensors, for example, which measure the distance to the upper surface of the stacked sheets 101, 102 and detect the remaining amount of the sheets 101, 102 based on the measured distance. Note that the remaining sheet sensors 31, 32 may be able to detect the remaining sheet quantity in increments of 1%, or the remaining sheet quantity at a predetermined level such as 0%, 30%, 50%, 80%, and 100%. May be detectable.

  FIG. 2 is a block diagram showing a part of the electrical configuration of the image forming apparatus according to the embodiment of the present invention. As shown in FIG. 2, the image forming apparatus includes a controller 41, a printing device 42, and an operation panel 43.

  The controller 41 includes a computer, an ASIC (Application Specific Integrated Circuit), etc., implements various processing units with software and / or hardware, monitors and controls internal devices such as the printing apparatus 42, and performs various data processing. .

  The controller 41 controls a toner source development, transfer and fixing by controlling a driving source (not shown) for driving the above-described roller, a bias application circuit for applying a development bias and a primary transfer bias, and exposure devices 2a to 2d. And a processing circuit for executing paper feeding, printing, and paper ejection. The developing bias is applied between the photosensitive drums 1a to 1d and the developing units 3a to 3d, respectively, and the primary transfer bias is applied between the photosensitive drums 1a to 1d and the intermediate transfer belt 4, respectively.

  The printing apparatus 42 is an internal device that prints a document image with a mechanical configuration as shown in FIG.

  The operation panel 43 includes a display device such as a liquid crystal display that displays an operation screen to the user, and an input device such as a touch panel that accepts user operations and hard keys.

  Furthermore, the controller 41 includes a storage device 51, a remaining paper amount acquisition unit 52, and a cassette open / close determination unit 53.

  The storage device 51 is a non-volatile storage device such as a flash memory that stores a remaining paper value indicating the remaining amount of paper detected by the remaining paper sensors 31 and 32 corresponding to the paper feed cassettes 11 and 12.

  The remaining paper amount acquisition unit 52 acquires a remaining paper value indicating the remaining amount of paper detected by the remaining paper amount sensor 31, and the remaining paper value detected by the remaining paper amount sensor 31 does not indicate that the paper is out. In this case, the remaining sheet value corresponding to the remaining sheet sensor 31 stored in the storage device 51 is updated with the acquired remaining sheet value.

  Similarly, the remaining paper amount acquisition unit 52 acquires a remaining paper value indicating the remaining amount of paper detected by the remaining paper amount sensor 32, and the remaining amount value detected by the remaining paper amount sensor 32 indicates that the paper has run out. When not shown, the remaining sheet value corresponding to the remaining sheet sensor 32 stored in the storage device 51 is updated with the acquired remaining sheet value.

  When the remaining paper value detected by the remaining sheet sensor 31 indicates that the sheet is out of paper, the cassette open / close determination unit 53 stores the remaining sheet value corresponding to the remaining sheet sensor 31 stored in the storage device 51. Is greater than a predetermined threshold value, it is determined that the paper feed cassette 11 is open. This threshold is set to be equal to or greater than the minimum change width (for example, 1%) of the remaining sheet value detected by the remaining sheet sensor 31. The threshold value may be set by a user operation on the operation panel 43.

  Note that the cassette open / close determination unit 53, when the remaining sheet value detected by the remaining sheet sensor 31 indicates that the sheet is out of paper, is stored in the storage device 51 and corresponds to the remaining sheet sensor 31. When the quantity value is equal to or smaller than the predetermined threshold value, it is determined that the paper feed cassette 11 is in the closed state and the paper has run out.

  Similarly, the cassette open / close determination unit 53, when the remaining sheet value detected by the remaining sheet sensor 32 indicates that the sheet is out, the sheet corresponding to the remaining sheet sensor 32 stored in the storage device 51. When the remaining amount value is larger than a predetermined threshold value, it is determined that the paper feed cassette 12 is in an open state.

  The cassette open / close determination unit 53 determines that the remaining paper amount corresponding to the remaining paper amount sensor 32 stored in the storage device 51 when the remaining amount value detected by the remaining paper amount sensor 32 indicates that the paper is out. When the amount value is equal to or smaller than the predetermined threshold value, it is determined that the paper feed cassette 12 is in the closed state and has run out of paper.

  When the remaining sheet sensor 31 and the remaining sheet sensor 32 are the same, the threshold for the remaining sheet sensor 32 is the same as the threshold for the remaining sheet sensor 31.

  The cassette open / close determination unit 53 corresponds to the remaining sheet sensor 31 stored in the storage device 51 when the remaining sheet value detected by the remaining sheet sensor 31 indicates that the sheet has run out. When the remaining sheet value to be performed is larger than a predetermined threshold value, a warning message indicating that the sheet feeding cassette 11 is open is displayed on the display device of the operation panel 43, and (b) stored in the storage device 51. When the remaining sheet value corresponding to the remaining sheet sensor 31 is equal to or less than a predetermined threshold, a warning message indicating that the sheet in the sheet feeding cassette 11 is out is displayed on the display device of the operation panel 43.

  Similarly, when the remaining sheet value detected by the remaining sheet sensor 32 indicates that the sheet has run out, the cassette open / close determination unit 53 (a) applies the remaining sheet sensor 32 stored in the storage device 51. When the corresponding remaining paper value is larger than a predetermined threshold value, a warning message indicating that the paper feed cassette 12 is open is displayed on the display device of the operation panel 43 and (b) stored in the storage device 51. When the remaining sheet value corresponding to the remaining sheet sensor 32 is equal to or less than a predetermined threshold value, a warning message indicating that the sheet in the sheet cassette 12 is out is displayed on the display device of the operation panel 43.

  Next, the operation of the image forming apparatus according to the first embodiment will be described. FIG. 3 is a flowchart for explaining the operation of the image forming apparatus according to the first embodiment.

  The remaining paper amount acquisition unit 52 acquires the remaining amount value of the paper cassettes 11 and 12 by the remaining paper amount sensors 31 and 32 repeatedly or periodically at a predetermined timing (step S1).

  The remaining paper amount acquisition unit 52 determines whether or not the remaining paper value of each of the paper remaining values of the paper feed cassettes 11 and 12 indicates that the paper is out (step S2). If it is not indicated that the sheet has run out, the remaining sheet value corresponding to the remaining sheet sensor 31 stored in the storage device 51 is updated with the acquired remaining sheet value (step S3).

  At this time, if at least one of the remaining sheet values of the sheet cassettes 11 and 12 indicates that the sheet is out of paper, the remaining sheet amount acquisition unit 52 indicates that the remaining sheet value indicates that the sheet is out of paper. Alternatively, the cassette open / close determination unit 53 is notified that the remaining sheet value of the remaining sheet sensor indicates that the sheet is out.

  When notified that the remaining sheet value indicates that the sheet is out of paper, the cassette open / close determining unit 53 determines the remaining sheet value stored in the storage device 51 for the notified sheet cassette or remaining sheet sensor. Reading from the storage device 51 (step S4), it is determined whether or not the read paper remaining value is larger than a predetermined threshold (step S5).

  When it is determined that the read paper remaining value is greater than the predetermined threshold, the cassette open / close determination unit 53 opens the notified paper cassette (or the paper cassette corresponding to the notified paper remaining sensor). And a warning message indicating that the paper feed cassette is open is displayed on the display device of the operation panel 43 (step S6).

  On the other hand, when it is determined that the read sheet remaining value is not greater than the predetermined threshold, the cassette open / close determination unit 53 notifies the notified sheet cassette (or the sheet cassette corresponding to the notified sheet remaining amount sensor). Is in the closed state and it is determined that the paper cassette is out of paper, and a warning message indicating that the paper cassette is out of paper is displayed on the display device of the operation panel 43 (step S7).

  As described above, according to the first embodiment, the remaining sheet sensors 31 and 32 detect the remaining sheets in the sheet feeding cassettes 11 and 12. The storage device 51 stores a remaining paper value indicating the remaining amount of paper detected by the remaining paper sensors 31 and 32. The paper remaining amount acquisition unit 52 acquires a paper remaining value indicating the remaining amount of paper detected by the remaining paper sensors 31 and 32, and the remaining paper value detected by the remaining paper sensors 31 and 32 is out of paper. Is not shown, the remaining sheet value stored in the storage device 51 is updated with the acquired remaining sheet value. The cassette open / close determination unit 53 determines that when the remaining sheet value detected by the remaining sheet sensors 31 and 32 indicates that the sheet is out, the remaining sheet value stored in the storage device 51 is greater than a predetermined threshold. Then, it is determined that the paper feed cassette is open.

  Accordingly, it is possible to accurately detect that the paper feed cassettes 11 and 12 are in the open state by the remaining paper amount sensors 31 and 32 without separately providing an open / close sensor for the paper feed cassettes 11 and 12.

Embodiment 2. FIG.

  The image forming apparatus according to the second embodiment of the present invention has the same basic configuration as that of the image forming apparatus according to the first embodiment, and the image forming apparatus according to the second embodiment further includes a manual feed tray during printing. 13 is required to close the uppermost paper feed cassette (the paper feed cassette 11 in this case) among the paper feed cassettes 11 and 12.

  Specifically, in the image forming apparatus according to the second embodiment, maintenance (for example, removal of a jam) is performed on a paper conveyance path (a place where the above-described conveyance roller 29 is installed) on the manual feed tray 13. In this case, the user or the like removes the uppermost sheet cassette (sheet feeding cassette 11) and accesses the sheet conveyance path on the manual feed tray 13 from below. When the cassette 11) is in the open state, the paper on the manual feed tray 13 is not correctly conveyed, and jamming occurs. Therefore, when the paper on the manual feed tray 13 is conveyed, it is required that the uppermost paper feed cassette (paper feed cassette 11) is in a closed state.

  In the second embodiment, the cassette open / close determination unit 53 is detected by the paper remaining amount sensor 31 of the uppermost paper feed cassette (paper feed cassette 11) when the manual feed tray is designated as the paper feed source for printing. When the remaining sheet value indicates that the sheet is out of paper, if the remaining sheet value stored in the storage device 51 is greater than a predetermined threshold value, it is determined that the uppermost sheet cassette is in an open state and printing is started (that is, , Paper feeding and conveyance from the manual feed tray 13 is prohibited.

  Next, the operation of the image forming apparatus according to the second embodiment will be described.

  The image forming apparatus according to the second embodiment performs the same operation as the image forming apparatus according to the first embodiment, and operates as follows when the manual feed tray 13 is designated as the paper supply source during printing.

  FIG. 4 is a flowchart for explaining the operation of the image forming apparatus according to the second embodiment.

  In the second embodiment, the controller 41 performs a copy job or a print job based on a user operation on the operation panel 43 or print data (for example, PDL (Page Description Language) data) transmitted from a host device (not shown). Accept the request. At that time, the controller 41 accepts designation of the paper feed source together with the request. In a copy job, a document image read by an image reading device (not shown) is printed by the printing device 42. In a print job, a document image formed from print data is printed by the printing device 42.

  When the manual feed tray 13 is designated as the paper supply source (step S21), the paper remaining amount acquisition unit 52 acquires the paper remaining value of the uppermost paper feed cassette 11 (step S22).

  The remaining paper amount acquisition unit 52 determines whether or not the remaining paper value of the paper cassette 11 indicates out of paper (step S23). If the remaining paper value does not indicate out of paper, the acquired paper The remaining paper value corresponding to the remaining paper sensor 31 stored in the storage device 51 is updated with the remaining amount value (step S24). Thereafter, the controller 41 executes the requested job including printing (step S25).

  At this time, if the remaining sheet value of the sheet cassette 11 indicates that the sheet is out of paper, the remaining sheet amount acquisition unit 52 indicates that the remaining sheet value of the sheet cassette 11 indicates that the sheet is out. The opening / closing determination unit 53 is notified.

  The cassette open / close determination unit 53 reads the remaining sheet value stored in the storage device 51 for the sheet cassette 11 or remaining sheet sensor 31 from the storage device 51 (step S26), and the read remaining sheet value is a predetermined value. It is determined whether or not it is larger than the threshold value (step S27).

  When it is determined that the read paper remaining value is greater than the predetermined threshold, the cassette open / close determination unit 53 determines that the paper feed cassette 11 is in an open state and a warning indicating that the paper feed cassette 11 is in an open state. The message is displayed on the display device of the operation panel 43 (step S28). After starting the display of the warning message, the controller 41 stands by without executing printing.

  Thereafter, the cassette open / close determination unit 53 monitors the remaining sheet value detected by the remaining sheet sensor 31 in the remaining sheet acquisition unit 52 and repeatedly determines whether or not the sheet feeding cassette 11 has been closed (step). S29).

  When the user notices the warning message, the user closes the paper feed cassette 11. When the user closes the paper feed cassette 11, the paper remaining amount value detected by the paper remaining amount sensor 31 changes from a value indicating the out of paper to a value corresponding to the remaining amount of paper at that time. The cassette open / close determination unit 53 determines that the paper feed cassette 11 is closed when detecting the change in the remaining sheet value.

  After the cassette open / close determining unit 53 determines that the paper feed cassette 11 is closed, the controller 41 executes the requested job including printing (step S25).

  As described above, according to the second embodiment, when the image forming apparatus according to the second embodiment transports the paper on the manual feed tray 13, the uppermost paper feed among the paper feed cassettes 11 and 12. When it is requested that the cassette is in a closed state, the cassette open / close determination unit 53 determines that the remaining sheet detected by the remaining sheet sensor 31 of the uppermost sheet cassette when the manual feed tray 13 is designated as a printing sheet supply source. When the quantity value indicates out of paper, if the remaining paper value stored in the storage device 51 is greater than a predetermined threshold value, it is determined that the uppermost sheet cassette is in an open state and printing is prohibited.

  As a result, in an image forming apparatus that requires that the uppermost sheet cassette among the sheet cassettes 11 and 12 be closed when the sheet on the manual feed tray 13 is conveyed, the uppermost sheet cassette is used. Without providing an open / close sensor, the open state of the uppermost sheet cassette can be detected, and use of the manual feed tray 13 when the uppermost sheet cassette is open can be prevented.

  Each embodiment described above is a preferred example of the present invention, but the present invention is not limited to these, and various modifications and changes can be made without departing from the scope of the present invention. It is.

  For example, in the first and second embodiments, distance sensors are used for the remaining sheet sensors 31 and 32. Instead, sensors that detect the remaining sheet quantity based on the positions of the lift numbers 21 and 24, and the like. May be used.

  In the second embodiment, the above warning message may be hidden by default setting and changed to a setting that can be displayed based on a user operation. Further, the above warning message may be set to be hidden or displayed according to the type of job.

  The present invention is applicable to, for example, an image forming apparatus.

11, 12 Paper feed cassette 13 Bypass tray 31, 32 Paper level sensor 43 Operation panel (example of display device)
51 Storage Device 52 Remaining Paper Size Acquisition Unit 53 Cassette Open / Close Determination Unit

Claims (4)

One or more paper cassettes;
A remaining paper sensor for detecting the remaining amount of paper in the paper cassette;
A storage device for storing a remaining paper value indicating the remaining amount of paper detected by the remaining paper sensor;
When the remaining paper value indicating the remaining amount of paper detected by the remaining sheet sensor is acquired and the remaining sheet value detected by the remaining sheet sensor does not indicate out of paper, the acquired remaining paper amount A remaining sheet amount acquisition unit that updates the remaining sheet value stored in the storage device with a value;
When the remaining sheet value detected by the remaining sheet sensor indicates that the sheet is out of paper, the sheet feeding cassette is opened when the remaining sheet value stored in the storage device is greater than a predetermined threshold. A cassette open / close determination unit that determines that
An image forming apparatus comprising: A display device,
When the remaining sheet value detected by the remaining sheet sensor indicates that the cassette is open / closed, the cassette open / close determining unit (a) determines that the remaining sheet value stored in the storage device is greater than a predetermined threshold value. When it is larger, a warning message indicating that the paper feed cassette is open is displayed on the display device, and (b) when the paper remaining value stored in the storage device is equal to or less than a predetermined threshold value, Displaying a warning message on the display device indicating that the paper cassette is out of paper;
The image forming apparatus according to claim 1. It is further equipped with a manual feed tray
When transporting paper on the manual feed tray, it is required that the uppermost paper feed cassette among the paper feed cassettes is in a closed state,
The cassette open / close determining unit, when a manual feed tray is designated as a printing paper supply source, when the remaining paper value detected by the remaining paper sensor of the uppermost sheet cassette indicates that the paper is out, If the remaining sheet value stored in the storage device is larger than the predetermined threshold, it is determined that the uppermost sheet cassette is in an open state, and the start of printing is prohibited;
The image forming apparatus according to claim 1.   The paper remaining amount sensor has a configuration in which an output value when the paper feed cassette is in an open state is the same as an output value when the paper is out of paper. The image forming apparatus according to claim 1.

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