Post-processing device, and image forming device

Abstract

To provide a sheet loading device comprising an upper stage tray and a lower stage tray, by which damage to a tray and a loaded article, that is generated due to elevating / lowering action of the tray is minimized by loading height of a paper sheet placed at a position of not being detected in the lower stage tray by detection means.SOLUTION: In a sheet loading device comprising an upper stage tray and a lower stage tray each that are movable upward / downward, there is provided detection means for detecting that external force is applied to the upper stage tray (load fluctuation) to detect the load fluctuation of the upper stage tray, when the lower stage tray collides with the upper stage tray during elevation thereof. When the load fluctuation of the upper stage tray exceeds a predetermined value, it is stopped to elevate the lower stage tray.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a sheet stacking device on which sheets are stacked, and an image forming apparatus and device equipped with the sheet stacking device. [Background technology]

[0002] The system is provided with a sheet stacking device for stacking discharged paper sheets onto which images have been recorded by an image forming device such as a copier, printer, or a combination machine of these, and the sheet stacking device is provided with a tray as a stacking means on which the paper sheets onto which images have been formed are stacked.

[0003] When such a sheet stacking device has the tray wait in the standby position, it stops at a position where the upper tray paper surface detection sensor S3 (lower tray paper surface detection sensor S5) can detect the topmost surface of the paper on the tray, as shown in Figure 9(A).

[0004] When the tray is full, it may take a long time for the user to remove the sheets from the tray. As shown in Fig. 9(B), when the removal of a large number of sheets is stopped halfway, the paper may be placed in a position that is not detected by the lower tray paper surface detection sensor S5. In that case, the paper P will not be detected and will wait in a position as shown in Fig. 9(C), so there is a problem that the stack height of the paper returned to a position where it is not detected by the tray sensor may cause the stack to get pinched by the raising and lowering operation of the tray.

[0005] In recent years, as a solution, a technology has been proposed that uses a two-phase encoder on the drive shaft to detect the movement of the tray and stop the tray from rising (see Patent Document 1), and a technology that stops the tray from rising based on the difference between the last rising load value in the sheet stacking area stored in RAM and the current rising load value in the standby area detected by a load sensor (see Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-53308 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-59039 [Summary of the Invention] [Problems to be Solved by the Invention]

[0007] In the mechanism detected by the encoder of the prior art, when the state of no input of the encoder signal continues for a certain period of time, it is detected as a collision, but it does not stop unless the state of no input of the encoder signal has elapsed for a predetermined time.

[0008] Also, in the mechanism for detecting the change in the current value of the driving means during the raising of the lower tray in the prior art, it is difficult to separate the driving current component and the current fluctuation component due to the collision from the current during the driving of the lower tray. Since a current change occurs due to an external factor such as the extraction of the loaded paper, it is difficult to set the threshold value of the current fluctuation component due to the collision. There are problems such as this.

[0009] The present invention has been made in view of the problems existing in such conventional technologies, and minimizes damage to the tray and the loaded objects generated by the lifting operation of the tray according to the stacking height of the paper returned to a position not detected by the detection means on the lower tray. It is an object of the present invention to provide a sheet stacking device. Another object is to provide an image forming apparatus including this sheet stacking device. [Means for Solving the Problems]

[0010] In order to solve the above problems, the sheet stacking device of the present invention has a device configuration including a control unit, a drive unit, and a detection unit that can be independently controlled for a first tray and a second tray on which sheets can be stacked, and the detection unit detects load fluctuations. In the lifting operation in which the distance between the first tray and the second tray becomes narrow, It is characterized by comprising means for detecting by a detection unit provided in the tray that stops when the first tray and the second tray, or the loads on the first tray and the second tray come into contact with each other.

Advantages of the Invention

[0011] According to the present invention, when the lower tray collides with the upper tray while the lower tray is rising, by detecting the current fluctuation of the upper tray or the upper encoder, it is possible to detect the lower encoder or the lower tray current earlier and more stably than detecting the lower encoder or the lower tray current, and minimize damage to the tray and the load.

[0012] From the image of the fluctuation of the load current of each tray at the time of tray contact shown in FIG. 10, the fluctuation of the load current of the upper tray is larger and faster than that of the lower tray. From the image of the fluctuation of the encoder pulses of each tray shown in FIG. 11, it is possible to detect the occurrence of the encoder pulses of the upper tray faster than the stop of the lower tray.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0014] Hereinafter, a finisher having a sheet loading device according to an embodiment of the present invention and an image forming apparatus having the finisher provided in the apparatus main body will be described with reference to the drawings.

[0015] FIG. 1 is a schematic cross-sectional view of an image forming apparatus according to an embodiment of the present invention. Examples of the image forming apparatus include an electrophotographic copying machine and an inkjet printer. Note that the numerical values are for reference and do not limit the present invention.

[0016] The image forming apparatus 100 includes an apparatus main body 100A and a finisher 119 as a sheet processing device. The finisher 119 includes a sheet loading device 300. An image reading device 100B is equipped above the apparatus main body 100A. The image reading device 100B includes a document reading unit 101 that reads a document and a document feeding unit 102 that feeds the document D to the document reading unit 101.

[0017] Note that the image forming apparatus 100 does not necessarily require the finisher 119. When the image forming apparatus 100 does not include the finisher 119, the sheet loading device 300 is provided in the apparatus main body 100A. Therefore, the sheet loading device 300 is not provided only in the finisher 119.

[0018] Original document D is placed on the document tray 103 of the document feeder 102 by the user, sequentially separated one by one by the feeder 104, and supplied to the registration roller pair 105. Subsequently, the original document D is temporarily stopped by the registration roller pair 105, looped to correct skew. Then, the original document passes through the introduction path 106, passes through the reading position 107 of the document reading unit 101, and the image formed on the surface of the original document is read by the document reading unit 101. The original document D that has passed through the reading position 107 passes through the discharge path 108 and is discharged onto the discharge tray 109 by the reversing roller pair 110.

[0019] Also, when the image reading device 100B reads both the front and back sides of the original document, first, the original document D passes through the reading position 107 of the document reading unit 101, and the image on one side of the original document is read. Then, the original document D passes through the discharge path 108, is switched back and conveyed by the reversing roller pair 110, is reversed front to back, and is sent to the registration roller pair 105 again. Then, the original document D is corrected for skew by the registration roller pair 105 in the same way as when reading the image on one side, passes through the introduction path 106, and the image on the other side is read at the reading position 107. Then, the original document D passes through the discharge path 108 and is discharged to the discharge tray 109 by the reversing roller pair 110.

[0020] On the other hand, the original document passing through the reading position 107 is irradiated with light from the illumination system 111. The reflected light reflected from the original document is guided to the optical element 113 (CCD or other element) by a plurality of mirrors 112 and converted into image data. Then, a laser scanner (not shown) in the apparatus main body 100A irradiates the photosensitive drum 114 as the image forming unit with laser light based on the image data. Then, a latent image is formed on the outer periphery of the photosensitive drum 114. The latent image is developed by toner supplied from a toner supply device (not shown) to become a toner image.

[0021] Also, the paper as a sheet such as paper or plastic film loaded in the cassette 115 is sent out from the cassette 115 according to the recording signal accompanying the toner image forming operation and enters between the photoreceptor drum 114 and the transferrer 116. Then, the paper has the toner image on the photoreceptor drum 114 transferred by the transferrer 116. The paper with the toner image transferred is heated and pressed by the fuser 117 while passing through the fuser 117, and the toner image is fixed.

[0022] When forming images on both sides of the paper, the paper with the image fixed on one side by the fuser 117 passes through the duplex path 118 provided on the downstream side of the fuser 117 and is sent again between the photoreceptor drum 114 and the transferrer 116, and the toner image is also transferred to the back side. Then, the paper has the toner image on the back side fixed by the fuser 117 and is discharged to the external finisher 119.

[0023] FIG. 2 is a schematic cross-sectional view along the paper conveyance direction of the finisher 119. The finisher 119 has a rear-end binding device 500 for binding the rear ends of the bundled papers and the like. The finisher 119 can also perform non-sort processing and sort processing. The finisher 119 is provided with a sheet stacking device 300. The sheet stacking device 300 is provided with an upper tray 18a, a lower tray 18b, a paper surface detection sensor S3, a paper surface detection sensor S5, etc., and is adapted to stack the papers discharged from the paper discharge port 36 of the finisher main body 119A.

[0024] The inlet roller pair 502 is adapted to receive the paper conveyed from the apparatus main body 100A into the finisher 119. The sort path 552 is adapted to guide the paper received by the inlet roller pair 502 to the discharge conveyance roller pair 560 during sort processing, non-sort processing, and rear-end binding processing. The flapper 551 is provided at the branch point between the sort path 552 and the bookbinding path 553 and is adapted to select between the sort path 552 and the bookbinding path 553.

[0025] In the case of non-sorting processing, the sheets guided to the sorting path 552 by the flapper 551 are discharged onto the liftable upper tray 18a or the lower tray 18b by the forward rotation of the reversible sheet discharge conveyance roller pair 560. Note that a punch unit (not shown) for punching near the trailing edge of the conveyed sheets may be attached between the apparatus main body 100A and the finisher 119.

[0026] In the case of sorting processing, the sheets guided to the sorting path 552 by the flapper 551 are stacked on the processing tray (intermediate tray) 630 by the forward rotation operation and then the reverse rotation operation of the sheet discharge conveyance roller pair 560. Then, the side edges and the trailing edges of the sheets are aligned. The sheets stacked in a bundle on the processing tray 630 are, after alignment processing, stapling processing by the stapler 601, etc. as required, and then discharged onto either the upper tray 18a or the lower tray 18b in two upper and lower stages by the sheet discharge conveyance roller pair 560.

[0027] The upper tray 18a and the lower tray 18b are each liftably attached to the finisher main body 119A. The upper tray 18a and the lower tray 18b include an upper tray motor 209a (DC brushless motor) and a lower tray motor 209b (DC brushless motor) as drive sources for forward and reverse rotation, and pinion gears 225a and 225b that rotate by the upper tray motor 209a and the lower tray motor 209b. The pinion gears 225a and 225b are engaged with a rack (not shown) formed on a part of the column 37 of the finisher main body 119A. Therefore, the upper tray 18a and the lower tray 18b are configured to move up and down along the column 37 when the upper tray motor 209a and the lower tray motor 209b rotate and the pinion gears 225a and 225b rotate.

[0028] In FIG. 2, the upper tray 18a, which is the first tray, moves up and down between the position detected by the upper tray lower limit sensor S1 or the position detected by the upper tray lower limit front sensor S31, and the upper tray upper limit sensor S33 that has passed above the paper discharge port 36a. The upper tray 18a moves up and down to the paper stacking position (the position detected by the paper surface detection sensor S3) where the paper discharged from the paper discharge port (discharge port) 36a can be stacked, and then descends as the stacked paper increases.

[0029] The lower tray 18b, which is the second tray, moves up and down between the position detected by the lower tray lower limit sensor S29 or the position detected by the lower tray lower limit front sensor S30, and the lower tray upper limit sensor S32 that has passed above the paper discharge port 36b. When the lower tray 18b is loaded with paper, it moves up to the paper stacking position detected by the paper surface detection sensor S5 of the lower tray.

[0030] After the lower tray 18b moves up to the paper stacking position detected by the paper surface detection sensor S5, it descends as the stacked paper increases. When the lower tray 18b stacks paper on the upper tray 18a waiting at the position detected by the paper surface detection sensor S3, it waits at a position that does not prevent the upper tray 18a from descending even when the paper stacking amount is maximum.

[0031] On the other hand, paper surface detection sensors S3 and S5 are provided at the paper discharge ports 36a and 36b that discharge paper or a bound stack of papers to the upper tray 18a and the lower tray 18b. The paper surface detection sensor S3 is configured to detect the uppermost surface of the paper stacked on the upper tray 18a or the paper stacking surface, which is the upper surface of the upper tray 18a when no paper is stacked. The upper tray 18a stops at a position that does not block the paper discharge port 36a due to the detected paper stacked on it or due to the upper tray 18a itself by the detection operation of the paper surface detection sensor S3. Also, the paper surface detection sensor S5 is configured to detect the uppermost surface of the paper stacked on the lower tray 18b or the paper stacking surface which is the upper surface of the lower tray 18b when no paper is stacked. The lower tray 18b is configured to stop at a position where it does not block the paper discharge port 36b by the detection operation of the paper surface detection sensor S5, by the stacked paper, or by the lower tray 18b itself.

[0032] The paper surface detection sensors S3 and S5 are arranged such that, by the stacked paper, or by the lower trays 18a and 18b themselves, an element that emits light on one side of the front side and the rear side of the finisher across the tray at a position where the paper discharge ports 36a and 36b are not blocked, and an element that receives light on the opposite side. When there is no stacked paper or tray between the light emitting element and the light receiving element, the light receiving element detects the light from the light emitting element, and when it is determined that the uppermost surface of the stacked paper or the tray is below the paper surface detection sensor, the tray is raised. When the tray is raised and the light from the light emitting element that emits light when detecting the uppermost surface of the stacked paper or the tray does not reach the light receiving element, at that time it is determined that the uppermost surface of the stacked paper or the tray has reached the standby position for paper stacking, and the raising of the tray is stopped.

[0033] In addition, the paper surface detection sensors S3 and S5 may be in a shape using a tiltable plate-like flag. When the paper or the upper tray 18a or the lower tray 18b touches the flag, the flag tilts, and when the flag blocks the light from the light emitting part to the light receiving part, it may be configured to detect the paper or the upper tray 18a or the lower tray 18b. The flag, the light emitting part, and the light receiving part are not shown. Note that the paper surface detection sensors S3 and S5 may be photo sensors. The photo sensor is configured to detect the position of the paper or the stack tray by receiving the reflected light irradiated from the light emitting part on the paper loaded on the upper tray 18a or the lower tray 18b or the stack tray at the light receiving part and measuring the reflection angle of the reflected light. The position detection signal of the upper tray 18a or the lower tray 18b detected by the paper surface detection sensor S3 is provided in the finisher main body 119A and input to the CPU 900 that controls the finisher 119. Note that the CPU 900 may be integrated with the CPU 200 that controls the apparatus main body 100A of the image forming apparatus, and the position detection signal of the stack tray may be sent to the integrated CPU.

[0034] Note that the upper tray 18a first descends downward from the paper surface detection sensor S3, then ascends, and stops ascending at the position detected by the paper surface detection sensor S3. Similarly to the upper tray 18a, the lower tray 18b first descends downward, then ascends, and stops ascending at the position detected by the paper surface detection sensor S5. This is to keep the distance between the topmost position of the paper loaded on the upper tray 18a and the lower tray 18b and the paper discharge ports 36a and 36b constant, making it easier to discharge the paper from the paper discharge ports 36a and 36b. Also, it is to prevent the upstream end of the paper loaded on the upper tray 18a from leaning on the snow catcher 25a and the upstream end of the paper loaded on the lower tray 18b from leaning on the snow catcher 25b.

[0035] In FIG. 2, the upper tray lower limit sensor S1 is configured to detect the lower limit position of the upper tray 18a that gradually descends as the stacked paper increases. The lower tray lower limit sensor S29 is configured to detect the lower limit position of the lower tray 18b.

[0036] The paper surface detection sensor (ascending detection means) S5 is provided below the upper tray lower limit sensor S1. By providing the paper surface detection sensor S5 below the upper tray lower limit sensor S1, when the upper tray 18a descends and loads paper, it is possible to prevent the upper tray 18a from colliding with the lower tray 18b that is waiting at the position where the paper loading surface is detected by the paper surface detection sensor S5. Alternatively, it is possible to prevent the descending upper tray 18a from colliding with the paper on the lower tray that is waiting at the position where the upper surface of the loaded paper is detected by the paper surface detection sensor S5. This position where the lower tray is waiting is referred to as the upper waiting position of the lower tray.

[0037] The upper tray lower limit pre-sensor S31 is provided above the upper tray lower limit sensor S1. The lower tray lower limit pre-sensor S30 is provided above the lower tray lower limit sensor S29. Since the upper tray 18a and the lower tray 18b are configured such that the paper loaded on the upper tray 18a and the lower tray 18b is detected by the paper surface detection sensors S3 and S5, they are configured to descend as the paper loading amount increases. For this reason, the distance between the uppermost surface of the paper loaded on the upper tray 18a and the lower tray 18b and the paper discharge ports 36a and 36b is kept constant, and the paper discharge port 36a is not blocked by the paper loaded on the upper tray 18a, and the paper discharge port 36b is not blocked by the paper loaded on the lower tray 18b.

[0038] Next, the part related to the control of the finisher of this embodiment will be described. FIG. 3 is a schematic control block diagram of the finisher of this embodiment. The control block diagrams of the main parts related to the control of this embodiment are shown in FIGS. 5 and 6.

[0039] The CPU 900 reads data from the ROM 901 based on input information from each sensor, the main body communication unit, the saddle communication unit, the puncher communication unit, etc., temporarily stores it in the RAM 902, and controls each motor, solenoid, etc. by the control unit 906. The ROM 901 and the RAM 902 are connected to the CPU 900 as a storage unit (storage means) 960.

[0040] As sensors for inputting signals to the CPU 900, there are a paper surface detection sensor S3 and S5, an upper tray lower limit front sensor S31, an upper tray lower limit sensor S1, an upper tray paper detection sensor S7, and a lower tray paper detection sensor S9. Further, as sensors, there are a lower tray lower limit front sensor S30, a lower tray lower limit sensor S29, and the like.

[0041] Also, as driving means for receiving a control signal from the CPU 900, there are the following motors, SL (solenoid), etc. Inlet conveyance motor. Discharge bundle motor. Swing motor. Front alignment motor. Rear alignment motor. Rear end assist motor. Upper tray motor 209a. Lower tray motor 209b. Stapler motor. Stapler shift motor. Other motors, solenoids, and the like.

[0042] Next, based on the flowchart of FIG. 4, the stack tray lift stop control by the finisher 119 will be described. It is assumed that the control processes shown in these flowcharts are executed by the CPU 900 in FIG. 3 according to a program stored in the ROM 901 in advance.

[0043] Based on the flowchart of FIG. 4, the discharge position tray paper surface detection operation will be described. Note that since the lifting operations for the upper tray 18a and the discharge port 36a and for the lower tray 18b and the discharge port 36b are the same, the lifting operation of the upper tray 18a will be described, and the description of the lifting operation of the lower tray 18b will be omitted.

[0044] The CPU 900 determines whether it is necessary to lower the upper tray 18a based on the state of the paper surface detection sensor S3. When the paper surface detection sensor S3 is ON (Yes in S402), the CPU 900 lowers the upper tray 18a (S403). Then, when the paper surface detection sensor S3 turns OFF (Yes in S404), the CPU 900 stops the lowering of the upper tray 18a (S405).

[0045] In this case, the upper tray 18a will have descended below the paper surface detection sensor S3. Also, in process S402, even if the paper surface detection sensor S3 is initially OFF (No in S402), the upper tray 18a will be below the paper surface detection sensor S3. Therefore, the CPU900 raises the upper tray 18a (S406) in order to make it wait at the paper discharge position where the upper tray 18a is detected by the paper surface detection sensor S3. Then, when the paper surface detection sensor S3 turns ON (Yes in S407), the CPU900 stops the raising of the upper tray 18a (S408) and completes the paper discharge position tray paper surface detection operation (S409).

[0046] As a result, the upper surface of the upper tray 18a or the upper surface of the paper stacked on the upper tray 18a will be positioned below the paper discharge port 36a, and it will be possible to stack paper on the upper tray 18a.

[0047] As described above, the raising operation continues from a position below the paper surface detection sensor S3 until the paper surface detection sensor S3 detects the uppermost part of the stacked paper surface.

[0048] Next, with reference to FIG. 5, a control block diagram showing the main parts related to the control of the present embodiment will be described.

[0049] In FIG. 5, the following various sensors, encoders, etc. are connected to the CPU. Upper tray upper limit sensor S33. Paper surface detection sensor S3. Upper tray lower limit front sensor S31. Upper tray lower limit sensor S1. Paper surface detection sensor S5. Lower tray lower limit front sensor S30. And lower tray lower limit sensor S29. Upper encoder 210a. Lower encoder 210b. Display panel 212. The CPU900 includes a counter 904, a comparison unit 905, etc. in addition to the control unit 906 shown in FIG. 2. A storage unit (storage means) 960 having a ROM901 and a RAM902 is connected to the CPU900.

[0050] Based on the input information of each sensor, the CPU 900 reads data from the ROM 901 of the storage unit 960, temporarily stores it in the RAM 902, and controls each motor and the like by the control unit 906.

[0051] The upper encoder 210a detects the position by counting the number of pulses of the upper tray motor 209a. The lower encoder 210b detects the position by counting the number of pulses of the lower tray motor 209b.

[0052] FIG. 6 is a control block diagram showing the main part related to the control when stopping the upper tray and the lower tray based on the load current of the motor. FIG. 10 is a flowchart for explaining the ascending stop processing operation of the upper tray 18a.

[0053] In the CPU in the control block diagram of FIG. 6, an upper A / D conversion circuit 211a and a lower A / D conversion circuit 211b are connected instead of the upper encoder 210a and the lower encoder 210b in FIG. 5. And the detection unit 911 is configured to detect the load current value of the upper tray when the lower tray loading paper abuts on the upper tray and the upper tray moves from the standby position. Since the other parts are the same as those in FIG. 5, the description of the same parts is omitted.

[0054] The stopped tray that is not the tray in operation performs position control. For example, when the lower tray is ascending, the upper tray performs position control and the stopped tray that is not the tray in operation stays at a predetermined standby position. As a result, the lower tray loading paper abuts on the upper tray and an upward pushing force is applied to the upper tray. Since the upper tray is performing position control, it tries to stay at the same position. Therefore, the operating direction of the lower tray is different from that of the upper tray, and it is detected that the lower tray loading paper has abutted on the upper tray by the instantaneous increase in the load current of the upper tray.

[0055] Also, the ROM 901 and the RAM 902 are connected to the CPU 900 as a storage unit (storage means) 960 also in FIG. 6.

[0056] Furthermore, the CPU 900 shown in FIG. 6 also reads data from the ROM 901 of the storage unit 960 based on the input information of each sensor, temporarily stores it in the RAM 902, and controls each motor and the like by the control unit 906.

[0057] The A / D conversion circuit that detects the load current converts the current supplied to the motor or the current supplied to the motor drive circuit into an analog voltage, further amplifies it with an amplifier such as an operational amplifier, and detects and compares it in a processing unit such as a CPU, and has a circuit configuration for detecting an increase or decrease in the load current.

[0058] In the above configuration, the upper A / D conversion circuit 211a, the lower A / D conversion circuit 211b, and the detection unit 911 constitute a load detection unit (load detection means, load current detection unit) 1950. The load detection unit 1950 detects fluctuations in the rising load of the upper tray 18a and the lower tray 18b based on the rising load current of the upper tray motor (drive source) 209a and the lower tray motor (drive source) 209a that raise the upper tray 18a and the lower tray 18b.

[0059] Here, this embodiment will be described. In this configuration, the upper tray 18a is taken as the first tray and the lower tray 18b is taken as the second tray, and the detection of tray contact during the ascent of the second tray will be described. When the second tray starts to rise, the load of the first tray is detected at this time. If the load is greater than a predetermined value stored in the storage unit in advance, the second tray is stopped and the contact of the tray is detected. If the load is less than or equal to the predetermined value stored in the storage unit in advance, it is determined that the normal operation is completed if the second tray operation has stopped, and the load detection is continued if the second tray is in operation.

[0060] FIG. 7 is a flowchart showing the above control.

[0061] S1101 Determine whether the second tray is in the rising operation.

[0062] In S1102, when it is determined in S1101 that the second tray is in the ascending operation, the load detection of the first tray is started.

[0063] In S1103, check whether the load of the first tray is less than or equal to a predetermined value stored in advance.

[0064] In S1103, if the load of the first tray is less than or equal to a predetermined value stored in advance, the operation continues, and the load detection of the first tray is performed when returning to S1102 until the operation is completed in S1104.

[0065] In S1103, if the load of the first tray is not less than or equal to a predetermined value stored in advance, the contact of the tray is detected in S1105, and the operation is stopped in S1106.

[0066] Note that the flow chart of the contact detection during the operation of the first tray is the same as the flow chart of the contact detection during the operation of the second tray, but with the ascending of the second tray replaced by the descending of the first tray, the first tray replaced by the second tray, and the second tray replaced by the first tray. Therefore, the description is omitted.

[0067] FIG. 8 is a flow chart for detecting the contact of the tray by detecting the encoder pulses of the first tray for the above control.

[0068] In S1201, determine whether the second tray is in the ascending operation.

[0069] In S1202, when it is determined in S1201 that the second tray is in the ascending operation, the encoder pulse detection of the first tray is started.

[0070] In S1203, check whether the number of encoder pulses of the first tray is less than or equal to / more than a predetermined number of pulses stored in advance.

[0071] In S1203, if the encoder pulses of the first tray are less than or equal to a predetermined number of pulses stored in advance, the operation continues, and the encoder pulse detection of the first tray is performed when returning to S1202 until the operation is completed in S1204.

[0072] In S1203, when the encoder pulse detection of the first tray is equal to or greater than a predetermined pulse stored in advance, the contact of the tray is detected in S1205, and the operation is stopped in S1106.

[0073] Note that the contact detection flow during the first tray operation is the same flowchart as the contact detection during the second tray operation, with the second tray rising replaced by the first tray descending, the first tray replaced by the second tray, and the second tray replaced by the first tray. Therefore, the description is omitted.

[0074] In the above-described embodiment, the tray was stopped at the time of contact detection. However, damage to the tray or the loaded items may be prevented by opening the distance between the first tray and the second tray by lowering the second tray, raising the first tray, or performing both operations.

[0075] Since the above flowchart only replaces the tray stops in S1106 and S1206 with the above operations, it is omitted.

Explanation of Signs

[0076] 18a: Upper tray (upper tray) 18b: Lower tray (lower tray) 209a: Upper tray motor 209b: Lower tray motor 225a, 225b: Pinion gears 37: Support pillar S1: Upper tray lower limit sensor S3: Upper tray paper surface detection sensor S5: Lower tray paper surface detection sensor S29: Lower tray lower limit sensor S30: Lower tray lower limit before sensor S31: Upper tray lower limit before sensor S32: Lower tray upper limit sensor S33: Upper tray upper limit sensor 900: CPU 901: ROM 902: RAM 904: Counter 906: Control unit 911: Detection unit 950: Load detection unit (load detection means) 960: Memory unit (memory means) 210a: Upper encoder 210b: Lower encoder 211a: Upper A / D conversion circuit 211b: Lower A / D conversion circuit 1950: Load detection unit (load detection means, load current detection unit)

Claims

1. a first tray on which sheets can be loaded, a second tray which is disposed under the first tray and on which sheets can be loaded, first driving means for enabling the first tray to move up and down, second driving means for enabling the second tray to move up and down, first control means for controlling the first driving means, second control means for controlling the second driving means, first detection means for detecting a load fluctuation of the first driving means, second detection means for detecting a load fluctuation of the second driving means, and in the lifting operation in which the distance between the first tray and the second tray becomes narrow, either the first tray or the second tray stops, and the other moves upward, or downward, and when the load fluctuation occurs when the load on the first tray and the second tray, or the first tray and the second tray comes into contact, the load fluctuation is detected by the first detection means or the second detection means of the stopped one of the first tray and the second tray, and the lifting operation of the first tray or the second tray is stopped, a sheet loading device characterized in that.

2. The detection means stops the lifting operation of the moving tray by detecting and comparing the load fluctuation generated by contact of the driving means of the stopped tray. The sheet loading device according to claim 1, characterized in that.

3. The detection means performs position detection by counting and comparing the number of pulses generated by contact of the driving means of the stopped tray, and stops the lifting operation of the moving tray. The sheet loading device according to claim 1, characterized in that.

4. When the load fluctuation occurs when the load on the first tray and the second tray, or the first tray and the second tray comes into contact, the load fluctuation is detected by the first detection means or the second detection means of the stopped one of the first tray and the second tray, and the first tray or the second tray that was performing the lifting operation is operated in the reverse direction, and the distance between the first tray and the second tray is widened, and the lifting operation is performed. The sheet loading device according to claims 1 to 3, characterized in that.

5. When the load fluctuation occurs when the load on the first tray and the second tray, or the first tray and the second tray comes into contact, the load fluctuation is detected by the first detection means or the second detection means of the stopped one of the first tray and the second tray, and the first tray or the second tray that was stopped ​ ​ ​ ​ Operate the second tray in the reverse direction and perform a lifting operation so that the distance between the first tray and the second tray increases. The sheet stacking device according to claims 1 to 3, characterized in that.

6. When the load fluctuation occurs when the load on the first tray and the second tray, or the first tray and the second tray comes into contact, the first detection means or the second detection means of the stationary one of the first tray and the second tray detects it, and the first tray and the second tray are moved up and down simultaneously so that the distance between the first tray and the second tray increases. The sheet stacking device according to claims 1 to 3, characterized in that. ​ ​

Images