Paper loading device and image forming apparatus

Abstract

To detect a height position of an uppermost surface of plural pieces of paper placed on a paper tray with space saving, low cost, and high accuracy.SOLUTION: A paper placing apparatus includes paper feeding means that feeds transported paper onto a paper tray, paper surface detection means that detects a height position of an uppermost surface of the plural pieces of paper placed on the paper tray, and lifting means that lifts the paper tray according to the height position detected by the paper surface detection means. A photosensor is used as the paper surface detection means.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a paper stacking device and an image forming apparatus. [Background technology]

[0002] The following Patent Document 1 discloses a technology that detects the height of the top surface of the paper stacked on the paper output tray by abutting the tip of a paper detection lever against the top surface of the paper stacked on the paper output tray, and raises and lowers the paper output tray according to that height. Summary of the Invention [Problem to be solved by the invention]

[0003] However, the technology of Patent Document 1 requires a relatively large and expensive paper detection lever to be provided above the multiple sheets of paper placed on the paper tray, and therefore the technology of Patent Document 1 cannot detect the height position of the top surface of the multiple sheets of paper placed on the paper tray in a space-saving, low-cost, and highly accurate manner. [Means for solving the problem]

[0004] In order to solve the above-mentioned problems, a paper loading device in one embodiment is provided with a paper discharge means for discharging transported paper onto a paper tray, a paper surface detection means for detecting the height position of the top surface of multiple papers loaded on the paper tray, and a lifting means for raising and lowering the paper tray according to the height position detected by the paper surface detection means, and uses a photosensor as the paper surface detection means. Effect of the Invention

[0005] According to one embodiment, the height position of the uppermost surface of a plurality of sheets of paper placed on a paper tray can be detected in a space-saving manner, at low cost, and with high accuracy. [Brief description of the drawings]

[0006] [Figure 1]FIG. 1 is a diagram showing an overall configuration of an image forming apparatus according to an embodiment; [Diagram 2] FIG. 2 is a diagram showing a specific configuration of a paper discharge unit included in an image forming apparatus according to an embodiment; [Diagram 3] FIG. 2 is a plan view showing a configuration around a paper tray in a paper discharge unit according to an embodiment; [Figure 4] FIG. 1 is a diagram showing an installation position of a paper surface detection sensor in a paper discharge unit according to an embodiment; [Diagram 5] FIG. 1 is a diagram showing an installation position of a paper surface detection sensor in a paper discharge unit according to an embodiment; [Figure 6] FIG. 2 is a diagram showing a functional configuration of an image forming apparatus according to an embodiment; [Figure 7] FIG. 1 is an activity diagram relating to detection of paper by a paper surface detection sensor and lowering control of a paper tray by a tray control unit in an image forming apparatus according to an embodiment. [Figure 8] FIG. 1 is a sequence diagram showing a processing sequence performed by an image forming apparatus according to an embodiment; [Figure 9] FIG. 13 is a diagram showing a modified example of the arrangement of the sheet surface detection sensor in the image forming apparatus according to the embodiment; [Figure 10] FIG. 13 is a diagram showing a modified example of the arrangement of the sheet surface detection sensor in the image forming apparatus according to the embodiment; [Figure 11] FIG. 13 is a diagram showing a modified example of the arrangement of the sheet surface detection sensor in the image forming apparatus according to the embodiment; [Figure 12] FIG. 13 is a diagram showing a modified example of the arrangement of the sheet surface detection sensor in the image forming apparatus according to the embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0008] (Configuration of image forming apparatus 100) Fig. 1 is a diagram showing an overall configuration of an image forming apparatus 100 according to an embodiment. Fig. 2 is a diagram showing a specific configuration of a paper discharge unit 130 included in the image forming apparatus 100 according to an embodiment.

[0009] 1 is an example of a "paper loading device" and an "image forming device", and is a device having at least a function of forming an image on paper P and a function of discharging paper P on which the image has been formed onto paper tray 136. Examples of image forming device 100 include an MFP (Multifunction Peripheral / Product / Printer) having a scanning function, a printer function, a FAX function, etc.

[0010] As shown in FIG. 1, the image forming apparatus 100 includes a paper feed section 110, a printing section 120, and a paper discharge section .

[0011] The paper feed unit 110 holds a plurality of sheets of paper P. Furthermore, the paper feed unit 110 supplies the sheets of paper P on which printing is to be performed to the printing unit 120. The paper feed unit 110 can hold and supply a plurality of types of paper P having different sizes and the like.

[0012] Printing unit 120 forms an image according to print data on the surface of paper P supplied from paper feed unit 110. For example, printing unit 120 has a liquid ejection head (not shown) capable of ejecting ink by an inkjet method, and forms a color image on the surface of paper P by ejecting ink of multiple colors using the liquid ejection head onto the surface of paper P. Printing unit 120 sends paper P on which the image has been formed to paper ejection unit 130.

[0013] The paper discharge section 130 discharges the paper P transported from the printing section 120. As shown in Fig. 1 and Fig. 2, the paper discharge section 130 includes a transport roller 131, a clip 133, a belt 134, a stack section 135, a paper tray 136, a paper surface detection sensor 137, a lifting mechanism 138, and a pair of left and right side panels 139R, 139L.

[0014] The conveying roller 131 conveys the paper P conveyed from the printing unit 120 to a position where the paper P can be held by the clip 133.

[0015] The clip 133 and the belt 134 are an example of a "paper discharge means." The clip 133 and the belt 134 are provided above the stack section 135. The clip 133 holds the leading end of the paper P transported by the transport roller 131. The belt 134 transports the paper P above the stack section 135 by moving the clip 133, which is holding the paper P, downstream. The clip 133 releases the paper P above the stack section 135. As a result, the clip 133 discharges the paper P to the stack section 135. The paper P discharged to the stack section 135 is placed on a paper tray 136 provided below the stack section 135.

[0016] The paper surface detection sensor 137 is an example of a "paper surface detection means." The paper surface detection sensor 137 detects the height position of the uppermost surface of a plurality of sheets of paper P placed on the paper tray 136. The lifting mechanism 138 is an example of a "lifting mechanism." The lifting mechanism 138 lifts and lowers the paper tray 136 according to the height position detected by the paper surface detection sensor 137.

[0017] 2, a leading edge aligning member 135A and a trailing edge aligning member 135B are provided at a target paper surface height position in stack section 135. Leading edge aligning member 135A moves rearward to bring the trailing edge of paper P into contact with trailing edge aligning member 135B, thereby aligning the leading edge and trailing edge of multiple paper sheets P placed on paper tray 136.

[0018] 2, a vertical, flat side panel 139 extending linearly in a direction parallel to the transport direction A of the paper P is provided above the paper tray 136 at a predetermined height position H1. As shown in FIG. 2, two sets of paper surface detection sensors 137 (paper surface detection sensor 137-1, paper surface detection sensor 137-2) are provided on the side panel 139 aligned in the front-rear direction (direction parallel to the transport direction A of the paper P). Other sensors (for example, a temperature sensor that detects the temperature of the paper tray 136) may be provided on the side panel 139.

[0019] FIG. 3 is a plan view showing a configuration of the vicinity of the paper tray 136 in the paper discharge section 130 according to an embodiment. As shown in FIG. 3, the paper discharge section 130 is provided with a pair of left and right side plates 139R, 139L above both left and right ends of the paper tray 136. Also, as shown in FIG. 3, the paper discharge section 130 is provided with two sets of paper surface detection sensors 137 (paper surface detection sensor 137-1, paper surface detection sensor 137-2). Each paper surface detection sensor 137 is configured with a light emitting section 137A and a light receiving section 137B, and is provided so that the light emitting section 137A and the light receiving section 137B face each other with respect to the pair of left and right side plates 139R, 139L. As a result, each paper surface detection sensor 137 can detect the height position of the uppermost surface of the multiple papers P placed on the paper tray 136 with a detection direction perpendicular to the conveying direction A of the paper P (i.e., the height direction of the paper P) (i.e., the width direction of the paper P).

[0020] Specifically, when light-receiving section 137B does not receive light emitted from light-emitting section 137A, each paper surface detection sensor 137 can detect paper P by determining that the light emitted from light-emitting section 137A is blocked by paper P. Lifting mechanism 138 can control the height position of the uppermost surface of multiple papers P placed on paper tray 136 to always be at a predetermined height position H1 by lowering paper tray 136 until paper P is no longer detected by paper surface detection sensor 137.

[0021] 3, the pair of left and right side plates 139 and the two sets of paper surface detection sensors 137 are provided outside the leading edge aligning member 135A and the trailing edge aligning member 135B in the left-right direction (the direction perpendicular to the conveying direction A). This prevents the pair of left and right side plates 139 and the two sets of paper surface detection sensors 137 from interfering with the leading edge aligning member 135A and the trailing edge aligning member 135B.

[0022] The image forming apparatus 100 of this embodiment uses a photosensor as the paper surface detection sensor 137. As a result, the image forming apparatus 100 of this embodiment can arrange the paper surface detection sensor 137 to the side of the multiple sheets of paper P placed on the paper tray 136, as shown in Figs. 3 and 4. Therefore, the image forming apparatus 100 of this embodiment does not need to provide a relatively large space above the multiple sheets of paper P placed on the paper tray 136 to arrange a paper detection member (for example, the paper detection lever of Patent Document 1). In addition, the image forming apparatus 100 of this embodiment does not need a paper detection member (for example, the paper detection lever of Patent Document 1) that abuts against the uppermost surface of the multiple sheets of paper P placed on the paper tray 136. Therefore, the image forming apparatus 100 of this embodiment can detect the height position of the uppermost surface of the multiple sheets of paper P placed on the paper tray 136 in a space-saving, low-cost, and highly accurate manner.

[0023] Furthermore, the image forming apparatus 100 of the present embodiment can detect the paper P from the side by the paper surface detection sensor 137, and therefore can detect paper P of various paper widths.

[0024] 4 and 5 are diagrams showing the installation positions of paper surface detection sensors 137-1 and 137-2 in paper discharge section 130 according to an embodiment. Fig. 4 shows a state in which B2 size paper P is placed on paper tray 136. Fig. 5 shows a state in which A3 size paper P is placed on paper tray 136.

[0025] 4 and 5, the paper discharge unit 130 according to an embodiment has paper surface detection sensors 137-1 and 137-2. Each of the paper surface detection sensors 137-1 and 137-2 has a light-emitting unit 137A and a light-receiving unit 137B arranged opposite each other, and the detection direction is a direction (i.e., the width direction of the paper P) perpendicular to the conveyance direction A of the paper P (i.e., the height direction of the paper P).

[0026] The paper surface detection sensor 137-1 is an example of a "first photosensor" and is provided near the rear end of the paper P placed on the paper tray 136. The paper surface detection sensor 137-1 can detect the height position of the rear end of the paper P, which is the part that is most likely to curl (i.e., the part that is most likely to be at the highest height). This allows the image forming apparatus 100 according to one embodiment to prevent the height position of the rear end of the paper P from being overlooked, and therefore prevents the rear end of the paper P from colliding with other paper P being transported by the transport rollers 131.

[0027] The paper surface detection sensor 137-2 is an example of a "second photosensor" and is provided near the center of the paper tray 136 in the transport direction A. As a result, the paper surface detection sensor 137-2 can detect the height position of the leading edge of the paper P, which is likely to curl (i.e., the height position is likely to be high) when the paper size of the paper P is relatively small and the leading edge of the paper P is located near the center of the paper tray 136 as shown in Fig. 5. Also, the paper surface detection sensor 137-2 can detect the height position of the center of the paper P, which is likely to float due to the air layer remaining when the paper P falls onto the paper tray 136 (i.e., the height position is likely to be high) when the paper size of the paper P is relatively large and the center of the paper tray 136 is located near the center of the paper tray 136 as shown in Fig. 4.

[0028] As shown in FIG. 4 and FIG. 5, the paper surface detection sensor 137-1 has the light-emitting unit 137A provided on the left side (i.e., the left side plate 139L) and the light-receiving unit 137B provided on the right side (i.e., the right side plate 139R). On the other hand, the paper surface detection sensor 137-2 has the light-emitting unit 137A provided on the right side (i.e., the right side plate 139R) and the light-receiving unit 137B provided on the left side (i.e., the left side plate 139L). That is, the light-emitting units 137A of the paper surface detection sensors 137-1 and 137-2 emit light in opposite directions. This makes it possible for the image forming apparatus 100 of this embodiment to suppress erroneous detection by the paper surface detection sensor 137 of the paper surface detection sensors 137-1 and 137-2 of the other paper surface detection sensor 137 of the paper surface detection sensors 137-1 and 137-2 of the other paper surface detection sensor 137. Furthermore, in the image forming apparatus 100 of this embodiment, even if one of the paper surface detection sensors 137-1, 137-2, 137- 1, receives disturbance light and is unable to detect the paper P normally, the other paper surface detection sensor 137 does not receive disturbance light and can detect the paper P normally.

[0029] Although the image forming apparatus 100 of the present embodiment has two paper surface detection sensors 137-1 and 137-2, the present invention is not limited to this. For example, the image forming apparatus 100 may have only one of the two paper surface detection sensors 137-1 and 137-2 (for example, only the paper surface detection sensor 137-1 that detects the rear end of the paper P). In this case, the image forming apparatus 100 can reduce costs compared to when it has two paper surface detection sensors 137-1 and 137-2.

[0030] Fig. 6 is a diagram showing a functional configuration of an image forming apparatus 100 according to an embodiment. As shown in Fig. 6, the printing unit 120 includes an image printing unit 721, a paper transport unit 722, and a communication unit 723. The image printing unit 721 forms an image on the surface of a paper P according to print data. The paper transport unit 722 transports the paper P on which the image has been formed to the paper discharge unit 130. The communication unit 723 communicates with the paper discharge unit 130 to transmit and receive various information (e.g., the transport status of the paper P) to and from the paper discharge unit 130.

[0031] As shown in FIG. 6, the paper discharge unit 130 includes a communication unit 731, a sensor monitoring unit 732, a tray control unit 733, a clip control unit 734, and a paper position alignment member control unit 735. The communication unit 731 communicates with the printing unit 120 to transmit and receive various information (e.g., the transport status of the paper P) to and from the printing unit 120. The sensor monitoring unit 732 monitors changes in the detection values ​​of various sensors related to the paper discharge unit 130 and notifies each control unit of the changes. The tray control unit 733 controls the lifting mechanism 138 to lift the paper tray 136. The clip control unit 734 controls the paper discharge operation of the clip 133 and the belt 134. The paper position alignment member control unit 735 controls the operation of aligning the leading end and trailing end of the paper P by the leading end alignment member 135A.

[0032] The printing unit 120 is not involved in the control of the paper discharge unit 130, but notifies the paper discharge unit 130 of the start and end of a paper discharge operation period. The paper discharge unit 130 starts and ends the paper discharge operation in response to the notification from the printing unit 120.

[0033] Each control unit of the image forming apparatus 100 can be realized by one or more processing circuits. In this specification, the term "processing circuit" includes a processor programmed to execute each function by software, such as a processor implemented by an electronic circuit, and devices such as an ASIC (Application Specific Integrated Circuit), a DSP (digital signal processor), an FPGA (field programmable gate array), and a conventional circuit module designed to execute each control unit of the image forming apparatus 100.

[0034] FIG. 7 is an activity diagram relating to detection of paper P by paper surface detection sensor 137 and lowering control of paper tray 136 by tray control unit 733 in image forming apparatus 100 according to one embodiment.

[0035] Immediately after the power is turned on, the paper discharge unit 130 disables the control of lowering the paper tray 136. When a notification of the start of printing is received, the paper surface detection sensor 137 detects the paper P, and the control of lowering the paper tray 136 becomes effective.

[0036] After printing starts, the tray control unit 733 of the paper discharge unit 130 lowers the paper tray 136 in response to a change in the detection value of the paper surface detection sensor 137. For example, when any one of the paper surface detection sensors 137 detects paper P, the tray control unit 733 lowers the paper tray 136 by a certain amount.

[0037] However, the tray control unit 733 includes in the condition for lowering the paper tray 136 that "the paper surface detection sensor 137 remains in a state where it detects the paper P for T seconds." Note that T may be any time, such as 5 seconds. As a result, in the image forming apparatus 100 according to one embodiment, when the paper P falls from the clip 133, the paper surface detection sensor 137 instantly detects the paper P, but this detection can prevent the paper tray 136 from being lowered by mistake.

[0038] FIG. 8 is a sequence diagram showing a processing sequence by the image forming apparatus 100 according to an embodiment.

[0039] (1.) First, the power of the printing unit 120 is turned on. (2.) Next, the power of the paper discharge unit 130 is turned on. (3.) Next, in the paper discharge unit 130, the sensor monitoring unit 732 monitors the sensor detection value of the paper surface detection sensor 137 by polling. (4.) Then, when printing starts in the printing unit 120, the communication unit 723 notifies the paper discharge unit 130 of the start of printing.

[0040] (5.) Next, in the paper discharge unit 130, when the communication unit 731 receives a notification of the start of printing from the printing unit 120, it notifies the tray control unit 733 of the start of printing. (6.) When the tray control unit 733 receives the notification of the start of printing, it starts waiting for a notification from the sensor monitoring unit 732.

[0041] (7.) Thereafter, when the paper surface detection sensor 137 detects the paper P, the sensor monitoring unit 732 notifies the tray control unit 733 that the paper P has been detected. (8.) Upon receiving the notification that the paper P has been detected, the tray control unit 733 starts measuring the duration of the state in which the paper P is detected.

[0042] (9.) Then, if the tray control unit 733 is notified by the sensor monitoring unit 732 that paper P is no longer detected before the duration reaches T seconds, (10.) the tray control unit 733 inquires of the sensor monitoring unit 732 about the detection values ​​of each paper surface detection sensor 137. (11.) As a result, if the detection values ​​of all the paper surface detection sensors 137 do not detect paper P, the tray control unit 733 returns the process to sequence 6. (12.) On the other hand, if the detection value of at least one of the paper surface detection sensors 137 detects paper P, the tray control unit 733 continues measuring the duration.

[0043] (13.) Then, when the duration reaches T seconds, the tray control unit 733 lowers the paper tray 136 by X mm, where X is a predetermined amount of lowering. For example, an optimal value for X is previously determined based on the threshold value T, the interval between paper P discharges, the thickness of paper P, and the like. (14.) After that, the tray control unit 733 queries the sensor monitoring unit 732 for the detection values ​​of each paper surface detection sensor 137. (15.) As a result, if the detection values ​​of all the paper surface detection sensors 137 do not detect paper P, the tray control unit 733 returns the process to sequence 6. (16.) On the other hand, if the detection value of at least one of the paper surface detection sensors 137 detects paper P, the tray control unit 733 returns the process to sequence 8.

[0044] When printing is completed in the printing unit 120, the communication unit 723 notifies the paper discharge unit 130 of the completion of printing. (17.) Then, in the paper discharge unit 130, when the communication unit 731 receives the notification of the completion of printing from the printing unit 120, it notifies the tray control unit 733 of the completion of printing. (18.) When the tray control unit 733 receives the notification of the completion of printing, it stops waiting for a notification from the sensor monitoring unit 732.

[0045] (Modification of the arrangement of the paper surface detection sensor 137) 9 to 12 are diagrams showing modified examples of the arrangement of the sheet surface detection sensor 137 in the image forming apparatus 100 according to one embodiment.

[0046] 9, the paper discharge section 130 of the image forming apparatus 100 may be provided with three or more paper surface detection sensors 137 arranged in a direction parallel to the transport direction A (i.e., the height direction of the paper P). For example, in the example shown in FIG. 9, the paper discharge section 130 further includes paper surface detection sensors 137-3 and 137-4 on both the left and right sides of the paper P placed on the paper tray 136, in addition to the paper surface detection sensors 137-1 and 137-2 described above. This allows the image forming apparatus 100 to detect the paper P at more points, thereby improving the detection accuracy of the paper P.

[0047] 10, the paper discharge section 130 of the image forming apparatus 100 may further include, in addition to the paper surface detection sensors 137-1 and 137-2 provided on both the left and right sides of the paper P placed on the paper tray 136, paper surface detection sensors 137-5 and 137-6 (examples of a "third photosensor" and a "fourth photosensor") provided in front and behind the paper P placed on the paper tray 136 and detecting directions parallel to the conveying direction A of the paper P (i.e., the height direction of the paper P) and along the right and left sides of the paper P. This allows the image forming apparatus 100 to detect the paper P over the entire outer periphery of the paper P, which is prone to curling, thereby improving the detection accuracy of the paper P.

[0048] 11 and 12, the paper discharge section 130 of the image forming apparatus 100 may be provided with two paper surface detection sensors 137-7 and 137-8 so that their detection directions cross on the paper P. In this case, as shown in Fig. 11 and 12, it is preferable that the paper surface detection sensor 137-7 (an example of a "fifth photosensor") is disposed on an extension of one diagonal of the paper P so that the detection direction of the paper surface detection sensor 137-7 (an example of a "fifth photosensor") is along one diagonal of the paper P, and the paper surface detection sensor 137-8 (an example of a "sixth photosensor") is disposed on an extension of the other diagonal of the paper P so that the detection direction of the paper surface detection sensor 137-7 (an example of a "sixth photosensor") is along the other diagonal of the paper P, so that the height positions of the diagonal corners and the center of the paper P can be detected. This allows the image forming apparatus 100 to detect the height positions of the four corners and center of the paper P, whose height position is likely to change due to curling, using the relatively small number of paper surface detection sensors 137, two. In this case, it is preferable to differentiate the positions of the paper surface detection sensors 137-7 and 137-8 according to the size of the paper P to be detected, as shown in Figures 11 and 12. In this case, it is also possible to differentiate the light emission timing of the paper surface detection sensor 137-7 from the light emission timing of the paper surface detection sensor 137-8, so that the light emitted by the paper surface detection sensor 137-7 and the light emitted by the paper surface detection sensor 137-8 do not interfere with each other.

[0049] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims. [Explanation of symbols]

[0050] 100 Image forming device 110 Paper feed section 120 Printing Department 130 Paper output section 131 Conveyor roller 133 clips 134 Belt 135 Stack Section 135A Tip Alignment Material 135B Rear end alignment member 136 Paper Tray 137 Paper surface detection sensor 137-1 Paper surface detection sensor (first photosensor) 137-2 Paper surface detection sensor (second photosensor) 137-3 Paper surface detection sensor 137-4 Paper surface detection sensor 137-5 Paper surface detection sensor (third photosensor) 137-6 Paper surface detection sensor (4th photosensor) 137-7 Paper surface detection sensor (5th photosensor) 137-8 Paper surface detection sensor (6th photosensor) 137A Light emitting part 137B Light receiving part 138 Lifting mechanism 139R Right side plate 139L Left side plate P paper H1 Height position [Prior art documents] [Patent documents]

[0051] [Patent Document 1] JP 2000-86055 A

Claims

1. a paper discharge means for discharging the conveyed paper onto a paper tray; a sheet surface detection means for detecting a height position of the uppermost surface of the plurality of sheets of paper placed on the sheet tray; The paper tray is raised or lowered according to the height position detected by the paper surface detection means. Lifting means and Equipped with As a means for detecting the surface of a sheet of paper, a first photosensor having a detection direction along one diagonal line of the paper; a second photosensor having a detection direction along the other diagonal line of the paper; Equipped with The positions of the first photosensor and the second photosensor are changed depending on the size of the paper. A paper loading device comprising:

2. The first photosensor and the second photosensor have a light-emitting portion and a light-receiving portion facing each other, and the light-emitting portions emit light in different directions.

2. The paper stacking device according to claim 1.

3. a paper discharge means for discharging the conveyed paper onto a paper tray; a sheet surface detection means for detecting a height position of the uppermost surface of the plurality of sheets of paper placed on the sheet tray; a lifting means for lifting and lowering the paper tray in accordance with the height position detected by the paper surface detection means; Equipped with As a means for detecting the surface of a sheet of paper, a first photosensor having a detection direction along one diagonal line of the paper; a second photosensor having a detection direction along the other diagonal line of the paper; Equipped with The positions of the first photosensor and the second photosensor are changed depending on the size of the paper.

1. An image forming apparatus comprising:

Images