Sheet feeding device and image forming system

Abstract

To provide a sheet feeding device capable of shortening a waiting time until a medium can be fed.SOLUTION: A bottom plate moving portion configured to move the bottom plate in a vertical direction, a height detecting portion configured to detect that a bottom plate lowermost surface as a lowermost surface of the bottom plate or a sheet uppermost surface as an uppermost surface of a sheet stacked on the bottom plate is present at a predetermined height, and a control portion configured to control a driving amount of the bottom plate moving portion according to a detection signal of the height detecting portion to adjust a lifting speed of the bottom plate; In the sheet feeding device, a plurality of height detection units are installed along the movement direction of the bottom plate, and the control unit estimates a temporary bottom plate range as a height position that the lowermost surface of the bottom plate can take corresponding to the installation position of the height detection unit and a temporary top surface range as a height position that the uppermost surface of the sheet can take corresponding to the installation position of the height detection unit in accordance with the detection signal from each of the height detection units, and adjusts the lifting speed of the bottom plate based on the estimated temporary bottom plate range and temporary top surface range.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sheet feeding device and an image forming system. [Background technology]

[0002] A sheet feeding device that sequentially feeds a plurality of stacked sheets of media starting from the top one is known, and an image forming system that is connected to an image forming apparatus that forms images on the media fed from the sheet feeding device is also known.

[0003] A sheet feeder used in conjunction with an image forming apparatus has a configuration in which a plate-shaped member carrying media can be moved up and down to increase the media capacity, and the plate-shaped member is raised as media is fed. The plate-shaped member carrying media moves the topmost medium to a media feed location (media outlet). In a sheet feeder with such a configuration, when refilling the plate-shaped member with media, the plate-shaped member must first be lowered to the lowest position in the media storage space, and then the plate-shaped member must be raised so that the topmost medium reaches the media outlet.

[0004] In the conventional movement control described above, the time it takes to raise the plate member until the top of the media reaches the media outlet is the waiting time until the media can be delivered. To shorten this waiting time, a configuration has been disclosed in which the bottom plate lifting speed is switched between two stages (see Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional technology disclosed in Patent Document 1, the bottom plate lifting speed is switched in two stages. Therefore, compared to the conventional technology, it is desirable to find a way to further shorten the waiting time until the medium is ready to be sent out.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a sheet feeding device that reduces the waiting time until a medium is ready to be fed, compared to the prior art. [Means for solving the problem]

[0007] In order to solve the above problem, one aspect of the present invention relates to a sheet supplying device that moves multiple sheets stacked on a bottom plate to a sheet supply port and supplies the sheets to the outside, and includes a bottom plate moving unit that moves the bottom plate in an up and down direction, a height detection unit that detects whether the bottommost surface of the bottom plate, which is the lowest surface of the bottom plate, or the topmost surface of the sheets, which is the topmost surface of the sheets stacked on the bottom plate, is at a predetermined height, and a control unit that controls the drive amount of the bottom plate moving unit in accordance with the detection signal of the height detection unit and adjusts the rising speed of the bottom plate, wherein multiple height detection units are installed along the moving direction of the bottom plate, and the control unit estimates a provisional bottom plate range as the height position that the bottommost surface of the bottom plate can take corresponding to the installation position of the height detection unit, and a provisional top surface range as the height position that the topmost surface of the sheets can take corresponding to the installation position of the height detection unit, in accordance with the detection signal from each of the height detection units, and adjusts the rising speed of the bottom plate based on the estimated provisional bottom plate range and provisional top surface range. [Effects of the Invention]

[0008] According to the present invention, it is possible to reduce the waiting time until the medium is ready to be supplied. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram illustrating an embodiment of an image forming system and a sheet feeding device according to the present invention; [Figure 2] FIG. 2 is a hardware configuration diagram of a control block of the paper feeder according to the embodiment of the present invention. [Figure 3] 10 is a flowchart showing an example of a bottom plate position etc. determination process according to the present embodiment. [Figure 4] 10 is a flowchart showing an example of a bottom plate rising speed adjustment process according to the present embodiment. [Figure 5] 10 is a graph showing an example of the correlation between the bottom plate rising speed and the remaining amount according to the present embodiment. [Figure 6] 10A and 10B are diagrams showing an example of a process for estimating the remaining amount and the bottom plate rising speed according to the present embodiment. [Figure 7] 10A and 10B are diagrams showing an example of a process for estimating the remaining amount and the bottom plate rising speed according to the present embodiment. [Figure 8] 10A and 10B are diagrams showing an example of a process for estimating the remaining amount and the bottom plate rising speed according to the present embodiment. [Figure 9] 10 is a graph showing an example of determining the bottom plate rising speed from the remaining amount according to the present embodiment. [Figure 10] 10A and 10B are diagrams showing an example of a process for estimating the remaining amount and the bottom plate rising speed according to the present embodiment. [Figure 11] 10A and 10B are diagrams showing an example of a process for estimating the remaining amount and the bottom plate rising speed according to the present embodiment. [Figure 12] 10A and 10B are diagrams showing an example of a process for estimating the remaining amount and the bottom plate rising speed according to the present embodiment. [Figure 13] 10 is a graph showing an example of determining the bottom plate rising speed from the remaining amount according to the present embodiment. [Figure 14] 10A and 10B are diagrams showing an example of a process for estimating the remaining amount and the bottom plate rising speed according to the present embodiment. [Figure 15] 10A and 10B are diagrams showing an example of a process for estimating the remaining amount and the bottom plate rising speed according to the present embodiment. [Figure 16] FIG. 10 is a schematic configuration diagram illustrating another embodiment of a sheet feeding device according to the present invention. [Figure 17] 10A and 10B are diagrams showing an example of a process for estimating the remaining amount and the bottom plate rising speed according to the present embodiment. [Figure 18] 10A and 10B are diagrams showing an example of a process for estimating the remaining amount and the bottom plate rising speed according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of a sheet feeding device and an image forming system according to the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram illustrating an embodiment of an image forming system according to the present invention. As shown in Fig. 1, an image forming system 10 is configured by connecting a paper feeding device 100 as an embodiment of a sheet feeding device and an image forming device 200 that forms an image on a sheet-like medium supplied from the paper feeding device 100.

[0011] In this embodiment, the sheet-like medium stacked and supplied by sheet feeding device 100 is assumed to be so-called "plain paper." In the following description, plain paper supplied by sheet feeding device 100 will be referred to as "paper P." Note that media that can be handled by sheet feeding device 100 is not limited to plain paper. Paper P may be any sheet-like medium that can be stacked on bottom plate 110, which will be described later. In other words, sheet-like media that can be used as paper P are of any type as long as they can be moved up and down by raising and lowering bottom plate 110 and can be supplied to image forming device 200.

[0012] Image forming apparatus 200 is an apparatus that forms an image on paper P using a predetermined image forming process, and is configured to receive paper P from paper feeder 100. The image forming processes that can be executed by image forming apparatus 200 are well known, so detailed explanations will be omitted.

[0013] As shown in FIG. 1, the sheet feeding device 100 includes a bottom plate 110, a plurality of sheet bottom plate detection sensors 120, a bottom plate driving unit 130, a delivery port 140, and a control unit 150.

[0014] The bottom plate 110 is a plate-like member on which paper sheets P are stacked. The bottom plate 110 can stack multiple sheets of paper sheets P and raises the stacked paper sheets P toward the delivery port 140, which serves as a sheet delivery section. In other words, the bottom plate 110 is supported by a structure that allows it to move in the vertical direction. The bottom plate 110 is also configured to be lowered to its lowest limit before the housing cover of the paper feeder 100 is opened when paper sheets P are replenished.

[0015] The paper bottom plate detection sensor 120 is a height detection unit for detecting the bottom plate 110 and the top surface of multiple sheets of paper P stacked on the bottom plate 110, and notifies the control unit 150 of a detection signal. Multiple paper bottom plate detection sensors 120 are installed at predetermined positions in the vertical direction of the storage space for paper P provided in the paper feeder 100. In this embodiment, the paper bottom plate detection sensors 120 are installed at equal intervals. However, the installation intervals of the paper bottom plate detection sensors 120 are not limited to equal intervals. The installation intervals of the paper bottom plate detection sensors 120 may be any interval as long as it is possible to control the amount and speed of lift of the bottom plate 110, which will be described later. Therefore, the installation intervals of the multiple paper bottom plate detection sensors 120 may be individually set within a range that controls the lift of the bottom plate 110, and the intervals between the paper bottom plate detection sensors 120 may vary.

[0016] The paper bottom plate detection sensor 120 may be any sensor capable of detecting that the bottom plate 110 and the topmost sheet of paper P stacked on the bottom plate 110 are present at predetermined positions. For example, the sensor may be an optical sensor having a light-emitting unit and a light-receiving unit, and the light-emitting unit and the light-receiving unit are disposed opposite each other in the horizontal direction of the paper feeder 100. When the light-receiving unit receives light from the light-emitting unit, the sensor operates to send a detection signal (a detection signal indicating a non-detection state) to the control unit 150 indicating that neither the paper P (including the topmost sheet) nor the bottom plate 110 is present at the installation position of the paper bottom plate detection sensor 120. In this embodiment, of the detection signals sent by the paper bottom plate detection sensor 120, a detection signal indicating that neither the paper P nor the bottom plate 110 is present at the predetermined position is referred to as an "OFF" signal.

[0017] On the other hand, when the light from the light emitting unit can no longer be received by the light receiving unit, the sensor operates to send a detection signal (a detection signal indicating a detection state) to the control unit 150, indicating that either the paper P (including the topmost sheet) or the bottom plate 110 is present at the installation position of the paper bottom plate detection sensor 120. Of the detection signals sent by the paper bottom plate detection sensor 120, a detection signal indicating that either the paper P or the bottom plate 110 is present at a predetermined position is set as an "ON" signal.

[0018] In this embodiment, for ease of explanation, each paper bottom plate detection sensor 120 is assigned a symbol corresponding to its installation position. For example, the paper bottom plate detection sensor 120 installed at the top (uppermost limit) of the range in which the bottom plate 110 can move is designated as paper bottom plate detection sensor 120(S1). The paper bottom plate detection sensor 120(S2) corresponds to the bottom (uppermost limit) of the range in which the bottom plate 110 can move, and when the distance from the bottom plate 110's lower limit (bottom plate lower limit) to the installation position of paper bottom plate detection sensor 120(S1) is assumed to be 100%, the paper bottom plate detection sensor 120(S2) corresponds to the 75% position. The paper bottom plate detection sensor 120(S3) corresponds to the 50% position, and the paper bottom plate detection sensor 120(S4) corresponds to the 25% position.

[0019] The bottom plate driving unit 130 supplies a driving force that enables the bottom plate 110 to move in the vertical direction. The magnitude of the driving force of the bottom plate driving unit 130 is controlled by the control unit 150. When the driving force supplied by the bottom plate driving unit 130 increases, the movement speed of the bottom plate 110 increases, and when the driving force decreases, the movement speed of the bottom plate 110 decreases.

[0020] The bottom plate driving unit 130 is, for example, an electric motor, and supplies a driving force according to the magnitude of the driving current value from the control unit 150. Note that if the bottom plate driving unit 130 is configured to raise the bottom plate 110 with a constant driving force, the raising speed of the bottom plate 110 will change according to the remaining amount of paper P loaded on the bottom plate 110. In other words, the raising speed of the bottom plate 110 increases as the remaining amount of paper P decreases.

[0021] The outlet 140 constitutes a sheet outlet portion that outputs the uppermost surface of the paper sheets P stacked on the bottom plate 110 to the outside.

[0022] The control unit 150 estimates the possible range of the bottom plate 110 and the position of the top surface of the sheets P stacked on the bottom plate 110 (hereinafter referred to as "top-most sheet surface Pt") based on the detection signal of the sheet bottom plate detection sensor 120. This estimated "possible range" is referred to as the estimated range. The control unit 150 calculates the remaining amount of sheets P according to the estimated range and the change in the detection signal of the sheet bottom plate detection sensor 120, and controls the operation of the bottom plate drive unit 130 based on this. The lifting speed of the bottom plate 110 is adjusted by the operation control of the bottom plate drive unit 130 by the control unit 150.

[0023] That is, the control unit 150 sequentially monitors changes in the detection signals of the multiple paper bottom plate detection sensors 120 to calculate an estimated range as the range of positions that the bottom plate 110 and the topmost paper surface Pt can take, and estimates the remaining amount of paper P stacked on the bottom plate 110 according to this estimated range. Then, the control unit 150 adjusts the lifting speed of the bottom plate 110 based on the "remaining paper amount," which is the estimated remaining amount of paper P. According to the above-described control of lifting the bottom plate 110, the position of the bottom plate 110 and the position of the topmost paper surface Pt can be accurately calculated regardless of the position at which the bottom plate 110 starts to lift, and the remaining paper amount can be sequentially updated and calculated, thereby sequentially adjusting (updating) the lifting speed of the bottom plate 110. Therefore, the waiting time until the supply of paper P can be started can be shortened compared to conventional technology.

[0024] [Control block of paper feeder 100] Next, the control block configuration of sheet feeding device 100 will be described with reference to Fig. 2. Fig. 2 is a hardware configuration diagram for executing control processing in sheet feeding device 100. As shown in Fig. 2, sheet feeding device 100 has control unit 150 including a configuration in which CPU (Central Processing Unit) 151, RAM (Random Access Memory) 152, ROM (Read Only Memory) 153, HDD (Hard Disk Drive) 154, and I / F 155 are connected via common bus 159.

[0025] The CPU 151 is a computing means and controls the overall operation of the sheet feeding device 100. The RAM 152 is a volatile storage medium that can read and write information at high speed, and is used as a work area when the CPU 151 processes information. The ROM 153 is a read-only nonvolatile storage medium that stores programs such as firmware. The HDD 154 is a nonvolatile storage medium that can read and write information and has a large storage capacity, and stores an OS (Operating System), various control programs, application programs, etc.

[0026] Sheet feeding device 100 processes a control program stored in ROM 153, an information processing program (application program) loaded into RAM 152 from a storage medium such as HDD 154, and the like using the arithmetic functions of CPU 151. This processing constitutes a software control unit including various functional modules of sheet feeding device 100. The combination of the software control unit thus constituted and hardware resources mounted on sheet feeding device 100 constitutes functional blocks that realize the functions of sheet feeding device 100. In other words, CPU 151, RAM 152, ROM 153, HDD 154, and I / F 155 constitute control unit 150 that controls the operation of sheet feeding device 100.

[0027] The I / F 155 is an interface that connects the plurality of paper bottom plate detection sensors 120 and the bottom plate driving unit 130 to a common bus 159 .

[0028] The control unit 150 controls the operation of the bottom plate driving unit 130 through the I / F 155. The control unit 150 also acquires detection signals from the plurality of paper bottom plate detection sensors 120.

[0029] [Embodiment of Bottom Plate Position and Topmost Paper Position Determination Process in Paper Feed Process Control Flow] Next, an example of control processing that can be performed in sheet feeding device 100 according to this embodiment will be described with reference to the flowchart shown in Fig. 3. Note that the control processing described below is a functional processing realized by executing a control program in control unit 150.

[0030] The control process shown in Figure 3 is a process included in a series of processes for supplying paper P from the outlet 140, and corresponds to a process for calculating and determining the positions of the bottom plate 110 and the top surface Pt of the paper based on multiple detection signals from the paper bottom plate detection sensor 120.

[0031] First, the parameters used in this control process are initialized (S301). In step S301, the values ​​of "top surface position" and "bottom plate position" are set to 0 (zero). Also, the top surface position flag and bottom plate position flag are set to "False." When the top surface position flag is "False," the position of the top surface Pt of the paper cannot be determined based on the detection signal of the paper bottom plate detection sensor 120. When the bottom plate position flag is "False," the position of the bottom plate 110 cannot be determined based on the detection signal of the paper bottom plate detection sensor 120.

[0032] Following the initialization process, the control unit 150 starts raising the bottom plate 110 (S302). While the bottom plate 110 continues to rise, if the upper surface position flag does not change from "False" to "True" (S303: NO), the control unit 150 adds the bottom plate rising amount to the upper surface position (S309) and proceeds to S304. If the upper surface position flag changes from "False" to "True" (S303: YES), the control unit 150 proceeds to S304 without adding the bottom plate rising amount to the upper surface position.

[0033] Next, if the bottom position flag does not change from "False" to "True" (S304: NO), the bottom plate lift amount is added to the bottom position (S310) and the process proceeds to S305. If the bottom position flag changes from "False" to "True" (S304: YES), the bottom plate lift amount is not added to the bottom position and the process proceeds to S305.

[0034] Next, the process from step S303 to step S305 is looped until a change occurs in the detection signal of any of the paper bottom plate detection sensors 120 (S305: NO). That is, the process from step S303 to S305 is looped, and the bottom plate 110 continues to rise, until the paper top surface Pt or the bottom plate 110 reaches the installation position of any of the paper bottom plate detection sensors 120 due to the rise of the bottom plate 110.

[0035] When the detection signal of any of the multiple paper bottom plate detection sensors 120 changes (S305: YES), it is determined whether the change is due to the detection signal changing from "ON" to "OFF" (S306). Note that the detection signal being "ON" means that either the bottom plate 110 or paper P is present at the installation position of the paper bottom plate detection sensor 120. Also, the detection signal being "OFF" means that neither the bottom plate 110 nor paper P is present at the installation position of the paper bottom plate detection sensor 120.

[0036] In step S306, if the change in the detection signal of any of the paper bottom plate detection sensors 120 is from ON to OFF (S306: YES), the position of the paper bottom plate detection sensor 120 where the detection signal changed is determined to be the bottom plate position, and the bottom plate position flag is set to "True" (S307).

[0037] Also, in step S306, if the change in the detection signal of any of the paper bottom plate detection sensors 120 is not from ON to OFF (S306: NO), the position of the paper bottom plate detection sensor 120 where the detection signal has changed is determined to be the top surface position, and the top surface position flag is set to "True" (S311).

[0038] Next, it is determined whether the top surface position flag and the bottom surface position flag are both "True" (S308), and the process returns to step S303 and is repeated until both are "True" (S308: NO). When both the top surface position flag and the bottom surface position flag are "True" (S308: YES), the position of the bottom plate 110 and the position of the top surface Pt of the paper are determined, and the process ends.

[0039] By the above procedure, the positions of the bottom plate 110 and the top surface Pt of the paper in the paper feeder 100 can be calculated with high accuracy.

[0040] That is, the bottom plate 110 starts to rise in a state where all of the detection signals from the plurality of paper bottom plate detection sensors 120 are "OFF" (neither the bottom plate 110 nor the paper P is present at the installation position).

[0041] After the bottom plate 110 starts to rise, when the detection signal of any one of the multiple paper bottom plate detection sensors 120 changes to "ON", it means that the top surface Pt of the paper has reached the position where the paper bottom plate detection sensor 120 that changed to ON is installed.

[0042] After the bottom plate 110 starts to rise, when the detection signal of any one of the multiple paper bottom plate detection sensors 120 changes to "OFF", it means that the underside of the bottom plate 110 (bottom plate underside) has passed the position where the paper bottom plate detection sensor 120 that changed to OFF is installed.

[0043] The positions of each of the multiple paper bottom plate detection sensors 120 are pre-stored in the memory of the control unit 150, so by determining the changes in the detection signals of the multiple paper bottom plate detection sensors 120 as described above, the control program of the control unit 150 can determine that the position of the bottom plate 110 and the position of the top surface Pt of the paper have reached the position of the paper bottom plate detection sensor 120 whose detection signal has changed.

[0044] In addition, by using the movement amount (lift amount) of the bottom plate 110 obtained from the drive amount of the drive motor that constitutes the bottom plate drive unit 130, the control unit 150 can sequentially track the movement amount of the bottom plate 110 from the position of the bottom plate 110 and the top surface Pt of the paper (the position of a certain paper bottom plate detection sensor 120) identified by changes in the detection signals of multiple paper bottom plate detection sensors 120.

[0045] Therefore, the control unit 150 can sequentially determine the position of the bottom plate 110 and the top surface of the paper that are in an intermediate position where the paper bottom plate detection sensor 120 is not installed.

[0046] [Embodiment of Bottom Plate Rising Speed ​​Adjustment Process in Paper Feed Process Control Flow] Next, another example of control processing that can be executed in sheet feeding device 100 according to this embodiment will be described with reference to the flowchart shown in Fig. 4. Note that the control processing described below is a functional processing realized by executing a control program in control unit 150.

[0047] The sheet feeding device 100 has a means for calculating the bottom plate rising speed based on the bottom plate position, the paper top surface position, and information that does not change while the bottom plate 110 is rising (such as the size of the paper P and the thickness of the paper P). The bottom plate driving unit 130 is composed of a motor or the like that can obtain the amount of rotation, and has a mechanism that can measure or calculate the amount of bottom plate rise with high resolution.

[0048] The control process according to this embodiment starts when the bottom plate 110 starts to rise (step S302 in FIG. 3), by acquiring sensor information from the detection signals of the multiple paper bottom plate detection sensors 120 (S401), and then determining the provisional bottom plate range and provisional top surface range (S402).

[0049] Here, the temporary bottom plate range refers to the range of height positions that the bottom plate 110 can assume when all detection signals of the multiple paper bottom plate detection sensors 120 are "OFF." When the temporary bottom plate range is estimated based on the detection signals, the installation position of the paper bottom plate detection sensor 120 (S1) whose relative installation position corresponds to the highest position is taken as the temporary bottom plate position. Also, when the detection signal of one of the multiple paper bottom plate detection sensors 120 is "ON," the position obtained by subtracting the installation interval of the paper bottom plate detection sensors 120 from the position of this "ON" paper bottom plate detection sensor 120 corresponds to the temporary bottom plate position.

[0050] The provisional top surface range refers to the range of height positions that the top surface of paper P can assume when all detection signals of the multiple paper bottom plate detection sensors 120 are "OFF." When the provisional top surface range is estimated based on the detection signals, the installation position of the paper bottom plate detection sensor 120 whose relative installation position corresponds to the highest position is defined as the provisional bottom plate position. In other words, the provisional bottom plate position corresponds to the position of the delivery opening 140 when the bottom plate 110 starts to rise. When the detection signal of one of the multiple paper bottom plate detection sensors 120 is "ON," the position obtained by adding the installation interval of the paper bottom plate detection sensors 120 from the position of this "ON" paper bottom plate detection sensor 120 corresponds to the provisional top surface position.

[0051] In step S402, among the bottom plate positions and paper top surface positions included in the provisional bottom surface range and provisional top surface range estimated from the detection state of the paper bottom plate detection sensor 120 before the bottom plate is raised, the provisional positions (provisional bottom surface position, provisional top surface position) are those that result in the slowest bottom plate rising speed.

[0052] Next, the parameters used in this control process are initialized (S403). In step S403, the "bottom surface position" is set to the temporary bottom surface position. Also, the "top surface position" is set to the temporary top surface position. Then, the top surface position flag and the bottom plate position flag are set to "False."

[0053] Following the initialization process, the control unit 150 determines a bottom plate rising speed using the provisional bottom plate range and provisional upper surface range (S404), and starts raising the bottom plate 110 at the determined bottom plate rising speed (S405). While the bottom plate 110 continues to rise, the control unit 150 adds the bottom plate rising amount to the bottom surface position (S406). If the upper surface position flag does not change from "False" to "True" (S407: YES), the control unit 150 adds the bottom plate rising amount to the upper surface position (S408), and proceeds to step S409. If the upper surface position flag does not change from "False" to "True" (S407: NO), the control unit 150 does not add the bottom plate rising amount to the upper surface position, and proceeds to step S409.

[0054] Next, when the detection signal of any of the plurality of paper bottom plate detection sensors 120 changes (S409: YES), it is determined whether the change is that the detection signal has changed from "ON" to "OFF" (S410).

[0055] In step S410, when the change in the detection signal of any of the paper bottom plate detection sensors 120 is from ON to OFF (S410: YES), the position of the paper bottom plate detection sensor 120 where the detection signal changed is determined to be the bottom plate position, and the bottom plate position flag is set to "True" (S411).

[0056] Also, in step S410, if the change in the detection signal of any of the paper bottom plate detection sensors 120 is not from ON to OFF (S410: NO), the position of the paper bottom plate detection sensor 120 where the detection signal changed is determined to be the top surface position, and the top surface position flag is set to "True" (S311).

[0057] Next, the bottom plate rising speed is updated (S413), and it is determined whether the topmost paper bottom plate detection sensor 120 among the multiple paper bottom plate detection sensors 120 is "ON" (S414), and the process returns to step S406 and repeats until it is "ON" (S414: NO). If the topmost paper bottom plate detection sensor 120 is "ON" (S414: YES), the process ends.

[0058] As described above, the control unit 150 adjusts the bottom plate rising speed by sequentially updating the provisional bottom plate range and provisional top surface range in accordance with the amount of rise of the bottom plate 110. When the detection state of the paper bottom plate detection sensor 120 changes, the bottom plate position or the paper top surface position is determined, and thereafter this value is used to adjust the bottom plate rising speed.

[0059] As described above, this control process makes it possible to increase the bottom plate lifting speed compared to conventional technology, and the initial position of the bottom plate 110 does not need to be at the lowest position, so that when replenishing paper P, it is possible to shorten the waiting time required to lift the bottom plate 110 from a lowered state to a state where paper P can be supplied. Below, a specific example of the control process for adjusting the bottom plate movement speed using this control process will be described with reference to the drawings.

[0060] For example, a case will be described in which the bottom plate 110 is detected before the top surface Pt of the paper is detected by the paper bottom plate detection sensor 120. Here, the difference between the position of the top surface Pt of the paper and the position of the bottom plate 110 is defined as the "remaining amount," and a function v(x) [% / sec] obtained from the value of this remaining amount (x%) is used to determine the bottom plate rising speed. Figure 5 is a graph illustrating the function v(x). As illustrated in Figure 5, the function v(x) is monotonically decreasing.

[0061] A method for determining the bottom plate lifting speed using the above function v(x) will be described with reference to Fig. 6. In this embodiment, the sheet feeding device 100 has four paper bottom plate detection sensors 120 installed, which, as already explained, are designated as "S1, S2, S3, S4" from top to bottom within the liftable space of the bottom plate 110.

[0062] [First Example] 6(a) represents the actual position of the bottom plate 110 and the remaining amount of paper P. In other words, the bottom plate 110 starts rising from a position that is 10% higher in the vertical direction of the storage space for paper P than the lowest position of the bottom plate 110. Also, it is assumed that paper P is loaded on the bottom plate 110 to a height equivalent to 20% of the vertical height of the storage space. In other words, the topmost paper surface Pt is at the 20% position.

[0063] 6(b) illustrates the provisional bottom surface range and provisional top surface range in the situation of FIG. 6(a). In this case, the position of the bottom plate 110 is below the lowest paper bottom plate detection sensor 120(S4), so the 0% position, which corresponds to the lowest position, is set as the provisional bottom surface position. Also, since the top surface Pt of the paper exceeds the lowest paper bottom plate detection sensor 120(S4), but does not exceed the paper bottom plate detection sensor 120(S3), which is located next to the lowest paper bottom plate detection sensor 120(S4), the position of this paper bottom plate detection sensor 120(S3) is set as the provisional top surface position.

[0064] In this case, as shown in FIG. 6(b), the range that can be taken by the bottom surface position, which is the actual position of the bottom plate 110, and the paper top surface position, which is the actual position of the topmost paper surface Pt, is the virtual position range Pr.

[0065] 6(b), paper bottom plate detection sensor 120(S1) is OFF, paper bottom plate detection sensor 120(S2) is OFF, paper bottom plate detection sensor 120(S3) is OFF, and paper bottom plate detection sensor 120(S4) is ON. In this case, the provisional bottom plate position is the 0% position when bottom plate 110 is at the lowest position, and the provisional top surface position is the 50% position, which is the position of paper bottom plate detection sensor 120[S3]. Therefore, the virtual position range Pr corresponds to 50%, which is the estimated value (provisional remaining amount) of the remaining amount of paper P stacked on bottom plate 110.

[0066] In this case, the bottom plate rising speed is "v(50)" when expressed by the function v(x) already explained, and the slowest speed is set.

[0067] Assume that the bottom plate 110 is raised from the situation in FIG. 6(a) to the situation illustrated in FIG. 7(a). In this case, as illustrated in FIG. 7(a), the amount of bottom plate lift until the bottom plate 110 rises to the position of the paper-sheet bottom plate detection sensor 120 (S4) is "15%." Until the amount of bottom plate lift reaches 15%, the virtual position range Pr gradually narrows. Then, just before the paper-sheet bottom plate detection sensor 120 (S4) turns ON, the temporary bottom plate position is at the 15% position. On the other hand, when the bottom plate 110 rises 15% and the paper-sheet bottom plate detection sensor 120 (S4) turns ON, the position of the bottom plate 110 is determined by the detection signal of the paper-sheet bottom plate detection sensor 120, so the temporary bottom plate position is not the 15% position but the 25% position.

[0068] 7(a), when the bottom plate 110 rises until the paper bottom plate detection sensor 120(S4) turns ON, the topmost paper surface Pt is at the 45% position and the paper bottom plate detection sensor 120(S3) remains OFF. Therefore, the provisional top surface position remains at 50%, so the virtual position range Pr is between 25% and 50%, and the provisional remaining amount is 25%.

[0069] That is, when the bottom plate 110 rises by 15%, the provisional remaining amount is changed from 50% to 25%. Since the control unit 150 determines the bottom plate rising speed using the provisional remaining amount as the remaining amount for the function v(x), the provisional remaining amount is changed to the remaining amount, and the bottom plate rising speed is changed from v(50) to v(25). That is, the rising speed of the bottom plate 110 becomes faster.

[0070] Suppose the bottom plate 110 is raised by another 5% from the situation illustrated in FIG. 7(a) to the situation illustrated in FIG. 8(a). In this case, the topmost sheet Pt is detected by the sheet bottom plate detection sensor 120(S3), so the sheet bottom plate detection sensor 120(S3) turns ON. As a result, as illustrated in FIG. 7(b), the virtual position range Pr remains between 25% and 50%, and the top sheet surface is determined to be at the 50% position. This determines the remaining amount as 25%.

[0071] Once the bottom surface position and the top surface position of the paper are determined and the remaining amount is determined, the rising speed of the bottom plate 110 is determined as v(25), and thereafter the bottom plate 110 rises at the rising speed of v(25) until the top surface Pt of the paper is detected by the paper bottom plate detection sensor 120(S1).

[0072] The correlation between the degree of rise of the bottom plate 110 (bottom plate rise amount) in Figures 6, 7, and 8 and the provisional bottom plate position, provisional top surface position, provisional remaining amount, and bottom plate rise speed is illustrated in the graph of Figure 9. Figure 9(a) illustrates the correlation between the change in provisional bottom plate position and the change in bottom plate rise amount. Figure 9(b) illustrates the correlation between the change in provisional top surface position and the change in bottom plate rise amount. Figure 9(c) illustrates the correlation between the change in provisional remaining amount and the change in bottom plate rise amount. Figure 9(d) illustrates the correlation between the change in bottom plate rise speed and the change in bottom plate rise amount.

[0073] As described above, because the temporary bottom plate position changes discontinuously, the bottom plate lifting speed also becomes discontinuous. (In reality, if the bottom plate driving unit 130 is configured with an electric motor, discontinuity may not occur due to the influence of the electric motor's slow-up time, etc.

[0074] [Second Example] Next, a case will be described where the topmost paper surface Pt is detected before the bottom plate 110 is detected by the paper bottom plate detection sensor 120. For example, as illustrated in Fig. 10(a), the actual position of the bottom plate 110 is 10% higher in the vertical direction of the storage space for the paper P than the lowest position, and the bottom plate 110 starts to rise from this position. Also, the height of the paper P stacked on the bottom plate 110 is equivalent to 30% of the vertical height of the storage space.

[0075] In this case, as shown in Figure 10(b), the provisional bottom surface position in the situation of Figure 10(a) is the 0% position, which corresponds to the lowest position, because the position of the bottom plate 110 is below the lowest paper bottom plate detection sensor 120(S4). Also, since the top surface Pt of the paper exceeds the lowest paper bottom plate detection sensor 120(S4), but does not exceed the paper bottom plate detection sensor 120(S3), which is located next to the lowest paper bottom plate detection sensor 120(S4), the position of this paper bottom plate detection sensor 120(S3) is taken as the provisional top surface position. In this case, as shown in Figure 10(b), the provisional remaining amount is 50%.

[0076] In this case, the bottom plate rising speed is "v(50)" when expressed by the function v(x) already explained, and the slowest speed is set.

[0077] Assume that the bottom plate 110 is raised from the situation in Fig. 10(a) to the situation illustrated in Fig. 11(a). In this case, as illustrated in Fig. 11(a), the paper bottom plate detection sensor 120 (S3) detects the topmost paper surface Pt when the bottom plate 110 is raised by 10%. This determines the top surface position as 50%.

[0078] 11(a) to 12(a), when the bottom plate 110 reaches a position detected by the paper bottom plate detection sensor 120 (S4), the already determined paper top surface will be at a position between 50% and 55%. Until the bottom plate 110 is detected, the provisional top surface range narrows by an amount corresponding to the bottom surface rise, and the bottom surface rise amount determined by the provisional top surface position increases. Therefore, the provisional remaining amount and the bottom plate rise speed remain constant until the bottom plate position is determined.

[0079] Then, when the bottom plate 110 reaches a position where it is detected by the paper bottom plate detection sensor 120 (S4), the bottom plate position is also determined. Just before the bottom plate 110 reaches a position where it is detected by the paper bottom plate detection sensor 120 (S4), the temporary bottom plate position is at the 15% position, but when it is detected by the paper bottom plate detection sensor 120 (S4), the temporary bottom plate position is at the 25% position.

[0080] As a result, the remaining amount is determined to be 30%, so the bottom plate rising speed is determined to be v(30), and thereafter the bottom plate 110 rises at the rising speed of v(230) until the topmost paper surface Pt is detected by the paper bottom plate detection sensor 120 (S1).

[0081] The correlation between the degree of rise of the bottom plate 110 (bottom plate rise amount) in Figures 10, 11, and 12 and the provisional bottom plate position, provisional top surface position, provisional remaining amount, and bottom plate rise speed is illustrated in the graph of Figure 13. Figure 13(a) illustrates the correlation between the change in provisional bottom plate position and the change in bottom plate rise amount. Figure 13(b) illustrates the correlation between the change in provisional top surface position and the change in bottom plate rise amount. Figure 13(c) illustrates the correlation between the change in provisional remaining amount and the change in bottom plate rise amount. Figure 13(d) illustrates the correlation between the change in bottom plate rise speed and the change in bottom plate rise amount.

[0082] As described above, because the temporary bottom plate position changes discontinuously, the bottom plate lifting speed also becomes discontinuous. (In reality, if the bottom plate driving unit 130 is configured with an electric motor, discontinuity may not occur due to the influence of the electric motor's slow-up time, etc.

[0083] [Third Example] When attempting to accurately determine the remaining amount using the procedures exemplified in the first and second embodiments, there are cases where the bottom plate ascent speed cannot be adjusted by the function v(x) depending on the position at which the bottom plate 110 starts rising. For example, it is difficult to determine the bottom plate position when the bottom plate 110 is located above the topmost paper bottom plate detection sensor 120 (S1), making it impossible to accurately determine the remaining amount. A case in which this occurs will be described as the third embodiment.

[0084] For example, as shown in Figure 14(a), let us consider a case in which bottom plate 110 starts rising while bottom plate 110 and the topmost paper surface Pt are present between bottom plate sensor 120(S1) and bottom plate sensor 120(S2) as the top height detectors. In this case, as shown in Figure 14(b), the provisional top surface position is the position of bottom plate sensor 120(S1), and the provisional bottom surface position is the position of bottom plate sensor 120(S2). Therefore, since the provisional remaining amount is 25%, the bottom plate rising speed is set to v(25).

[0085] Suppose bottom plate 110 is raised to change the situation from Figure 14(a) to Figure 15(a). In this case, as illustrated in Figure 15(a), bottom plate 110 does not cause a change in the state of bottom plate detection sensor 120 (no bottom plate detection sensor 120 changes from OFF to ON). Therefore, even if the top surface Pt of the paper is detected by bottom plate detection sensor 120 (S1), the bottom plate position is not determined, as illustrated in Figure 15(b), and therefore the bottom plate rising speed cannot be determined when the remaining amount is between 10% and 15%.

[0086] That is, there is room for further improvement in the first and second embodiments in that the remaining amount (loaded amount of paper P) stacked on the bottom plate 110 can be calculated with high accuracy successively even between the installation positions of the paper bottom plate detection sensor 120, and the bottom plate rising speed can be adjusted. Therefore, further improvements to the first and second embodiments will be described as a third embodiment.

[0087] [Third Example] For example, as shown in Fig. 16, the sheet feeding device 100 further includes a paper bottom plate detection sensor 120 (S5) as a lowest height detection unit for detecting when the bottommost surface of the bottom plate 110, which serves as the lowest surface of the bottom plate, is at the lowest limit position. The bottom plate 110 is lowered until one of the paper bottom plate detection sensors 120 (S1 to S5) turns ON, and then the bottom plate 110 starts to rise. This allows the control process for adjusting the bottom plate rising speed, as already explained, to be suitably executed.

[0088] 16, in the paper feeder 100, a filler 121 is provided as a bottom surface detector that is installed between the paper bottom plate detection sensor 120(S1) as the top height detector and the paper bottom plate detection sensor 120(S2) that is installed next to the top, and that detects the presence of the bottom plate 110. When the filler 121 detects the bottom plate 110, it first lowers the bottom plate 110 and then starts to raise it.

[0089] As a result, when the range of the downward movement is narrowed, the top surface Pt of the paper is always at a position higher than the paper bottom plate detection sensor 120 (S2). Therefore, the waiting time until the paper feed waiting state is shortened, so using this measure has little effect on reducing the waiting time.

[0090] [Fourth Example] Furthermore, the fourth embodiment is set up with the innovations in the first and second embodiments. As illustrated in FIG. 17, it is assumed that when the topmost paper surface Pt reaches the paper bottom plate detection sensor 120 (S1), which is the highest height detection unit, so many papers P are stacked on the bottom plate 110 that all of the paper bottom plate detection sensors 120 (S5 to S1) turn ON. For example, as illustrated in FIG. 17(a), it is assumed that when the bottom plate 110 is at the 10% position, the topmost paper surface Pt is at the 90% position. In this case, as illustrated in FIG. 17(b), the provisional bottom plate position is at the 0% position, and the provisional top surface position is at 100%.

[0091] If the bottom plate 110 is raised by 10% from the situation shown in Fig. 17(a), the situation shown in Fig. 18(a) will occur. In this case, as shown in Fig. 18(b), the amount of bottom plate lift is 10%, so the provisional bottom plate position is 10%, but the bottom plate 110 has not yet reached a position where it can be detected by the paper bottom plate detection sensor 120 (S4). Therefore, the bottom plate position is undetermined.

[0092] Meanwhile, since the top surface Pt of the paper reaches a position detected by the paper bottom plate detection sensor 120 (S1), the top surface position is determined to be 100%. However, since the bottom surface position is not determined, the provisional remaining amount remains undetermined at 90%. In other words, the remaining amount, assuming that the top surface Pt of the paper has reached the top, cannot be determined to be between 75% and 90%.

[0093] Therefore, in the case of a situation such as that illustrated in Figure 17(a), a paper bottom plate detection sensor 120 (S5) as the highest height detection unit is installed at the lowest limit, i.e., 0%, position, which is the limit position for the descent of the bottom plate 110, and the bottom plate 110 is lowered until it is detected by the paper bottom plate detection sensor 120 (S5), and then the process of raising the bottom plate 110 is started.

[0094] As a result, when the range of the downward movement is narrowed, the top surface Pt of the paper is always at a position higher than the paper bottom plate detection sensor 120 (S2). Therefore, the waiting time until the paper feed waiting state is shortened, so using this measure has little effect on reducing the waiting time.

[0095] According to the paper feeder 100 described above, by using a plurality of paper bottom plate detection sensors 120 that detect whether paper P or bottom plate 110 is present, it is possible to know the range of possible positions of the paper top surface and bottom plate position.

[0096] Furthermore, by using a means in control unit 150 that obtains with high resolution the detection signal from paper bottom plate detection sensor 120 and the amount of lift of bottom plate 110 by bottom plate drive unit 130, it is possible to narrow the range of possible positions of the paper top surface and bottom plate position over time. This allows the bottom plate lift speed to be updated sequentially along with the update of the range of possible positions of the paper top surface and bottom plate position, so the lift speed of bottom plate 110 can be changed continuously rather than just in two stages, and the time from when paper P is set on bottom plate 110 to when it becomes ready to feed paper can be shortened.

[0097] As already explained, the control method by the control unit 150 described above is realized by cooperation between the hardware resources of a computer and a program as computer software. That is, the control method is a method executed by a computer by causing an arithmetic unit, a storage unit, an input unit, an output unit, and a control unit to operate in cooperation based on the program. The program may also be written to a storage unit or a storage medium, etc., and distributed, or distributed via a telecommunications line, etc.

[0098] Furthermore, the present invention is not limited to the above-described exemplary embodiments, and various modifications are possible without departing from the technical gist thereof. The present invention covers all technical matters included in the technical ideas described in the claims. The above-described embodiments are preferred examples, but a person skilled in the art can realize various modifications from the disclosed content. Such modifications are also included in the technical scope described in the claims.

[0099] For example, aspects of the present invention are as follows. <1> A sheet feeding device that moves a plurality of sheets stacked on a bottom plate to a sheet feeding port and feeds the sheets to an outside, a bottom plate moving unit that moves the bottom plate in the up and down direction; a height detection unit that detects whether a bottom surface of the bottom plate, which is the lowest surface of the bottom plate, or an uppermost surface of the sheets, which is the uppermost surface of the sheets stacked on the bottom plate, is at a predetermined height; a control unit that controls the drive amount of the bottom plate moving unit in response to a detection signal from the height detection unit and adjusts the lifting speed of the bottom plate; Equipped with The height detection unit is provided in plurality along the moving direction of the bottom plate, The control unit estimates a provisional bottom plate range as a height position that the bottom surface of the bottom plate can assume corresponding to the installation position of the height detection unit, and a provisional upper surface range as a height position that the top surface of the seat can assume corresponding to the installation position of the height detection unit, in response to the detection signal from each of the height detection units; adjusting the rising speed of the bottom plate based on the estimated provisional bottom plate range and provisional top surface range; The sheet supplying device is characterized by the above. <2> The control unit The width between the provisional bottom plate range and the provisional top surface range is estimated to be narrowed in accordance with the rise of the bottom plate. The aforementioned <1> 2 is a sheet feeding device according to the first embodiment. <3> The control unit changing the rising speed of the bottom plate according to changes in the provisional bottom plate range and the provisional top surface range; The aforementioned <1> or <2> 2 is a sheet feeding device according to the first embodiment. <4> The control unit The detection signals of the height detection units, which change in response to the rise of the bottom plate, change to either a non-detection state in which the bottom plate or the top surface of the sheet is not detected to be at a predetermined height, or a detection state in which one of the detection signals of the height detection units detects that the bottom plate or the top surface of the sheet is at a predetermined height, and the width of the provisional bottom plate range and the provisional top surface range is estimated to be narrowed depending on the manner of change. The aforementioned <1> ~ <3> 10. The sheet feeding device according to claim 9, wherein the sheet feeding device is a sheet feeding device having a plurality of nozzles. <5> The height detection units are installed at equal intervals within a range in which the bottom plate can move. The aforementioned <1> ~ <4> 10. The sheet feeding device according to claim 9, wherein the sheet feeding device is a sheet feeding device having a plurality of nozzles. <6> The height detection unit This is realized by detecting whether the bottom plate or the sheets stacked on the bottom plate are at a predetermined height. The aforementioned <1> ~ <5> 10. The sheet feeding device according to claim 9, wherein the sheet feeding device is a sheet feeding device having a plurality of nozzles. <7> The control unit Before the bottom plate is raised, the control unit detects whether the bottom plate or the sheets stacked on the bottom plate are at a predetermined height, depending on the state of the height detection unit. The width between the provisional bottom plate range and the provisional top surface range is estimated to be narrowed. The aforementioned <6> 2 is a sheet feeding device according to the first embodiment. <8> A lowest height detection unit is further provided at a height position corresponding to the lowest limit of the range in which the bottom plate can move, The control unit a non-detection state in which neither the height detection unit nor the lowest height detection unit detects that the bottom plate or the seat is at a predetermined height, Before raising the bottom plate, the bottom plate is lowered until either the height detection unit or the lowest height detection unit detects that the bottom plate or the sheet is at a predetermined height. The aforementioned <6> or <7> 2 is a sheet feeding device according to the first embodiment. <9> The control unit the height detection units, excluding the uppermost height detection unit placed at a height position corresponding to the uppermost limit of the range in which the bottom plate can move, are in a detection state in which they detect that the bottom plate or the seat is at a predetermined height, Furthermore, when the lowest height detection unit is in a non-detection state where it does not detect that the bottom plate or the seat is at a predetermined height, Before raising the bottom plate, the bottom plate is lowered until the lowest height detection unit installed at the lowest position detects that the bottom plate or the sheet is at a predetermined height. The aforementioned <8> 2 is a sheet feeding device according to the first embodiment. <10> a bottom plate detector that detects the presence of the bottom plate between a top height detector, which is the height detector installed at the upper limit of the movement range of the bottom plate, and a height detector installed at the next height position after the top height detector; The control unit When none of the height detection units is in a non-detection state where it does not detect that the bottom plate or the seat is at a predetermined height, and the bottom plate detection unit is in a detection state where it detects the bottom plate, Before raising the bottom plate, the bottom plate is lowered until any one of the height detection units changes to a detection state that detects that the bottom plate is at a predetermined height. The aforementioned <6> ~ <9> 10. The sheet feeding device according to claim 9, wherein the sheet feeding device is a sheet feeding device having a plurality of nozzles. <11> an image forming device that forms an image on a sheet; The sheet is supplied to the image forming apparatus. <1> ~ <10> and an image forming system including the sheet feeding apparatus according to any one of the above. [Explanation of symbols]

[0100] 10: Image forming system 11: Bottom plate 100: Paper feeder 110: Bottom plate 120: Paper bottom plate detection sensor 121: Filler 130: Bottom plate drive unit 140: Outlet 150: Control unit 151: CPU 152:RAM 153:ROM 154: HDD 155: Interface 159: Common bus 200: Image forming device [Prior art documents] [Patent documents]

[0101] [Patent Document 1] Japanese Patent Application Publication No. 2019-108202

Claims

1. A sheet feeding device that moves a plurality of sheets stacked on a bottom plate to a sheet feeding port and feeds the sheets to an outside, a bottom plate moving unit that moves the bottom plate in the up and down direction; a height detection unit that detects whether a bottom surface of the bottom plate, which is the lowest surface of the bottom plate, or an uppermost surface of the sheets, which is the uppermost surface of the sheets stacked on the bottom plate, is at a predetermined height; a control unit that controls the drive amount of the bottom plate moving unit in response to a detection signal from the height detection unit and adjusts the lifting speed of the bottom plate; Equipped with The height detection unit is provided in plurality along the moving direction of the bottom plate, The control unit estimates a provisional bottom plate range as a height position that the bottom surface of the bottom plate can assume corresponding to the installation position of the height detection unit, and a provisional upper surface range as a height position that the top surface of the seat can assume corresponding to the installation position of the height detection unit, in response to the detection signal from each of the height detection units; adjusting the rising speed of the bottom plate based on the estimated provisional bottom plate range and provisional top surface range; A sheet feeding device characterized by:

2. The control unit The width between the provisional bottom plate range and the provisional top surface range is estimated to be narrowed in accordance with the rise of the bottom plate. The sheet feeding device of claim 1 .

3. The control unit changing the rising speed of the bottom plate according to changes in the provisional bottom plate range and the provisional top surface range; The sheet feeding device of claim 1 .

4. The control unit The detection signals of the height detection units, which change in response to the rise of the bottom plate, change to either a non-detection state in which the bottom plate or the top surface of the sheet is not detected to be at a predetermined height, or a detection state in which one of the detection signals of the height detection units detects that the bottom plate or the top surface of the sheet is at a predetermined height, and the width of the provisional bottom plate range and the provisional top surface range is estimated to be narrowed depending on the manner of change. The sheet feeding device of claim 1 .

5. The height detection units are installed at equal intervals within a range in which the bottom plate can move. The sheet feeding device according to any one of claims 1 to 4.

6. The height detection unit This is realized by detecting whether the bottom plate or the sheets stacked on the bottom plate are at a predetermined height. The sheet feeding device of claim 1 .

7. The control unit Before the bottom plate is raised, the control unit detects whether the bottom plate or the sheets stacked on the bottom plate are at a predetermined height, depending on the state of the height detection unit. The width between the provisional bottom plate range and the provisional top surface range is estimated to be narrowed. The sheet feeding device according to claim 6 .

8. A lowest height detection unit is further provided at a height position corresponding to the lowest limit of the range in which the bottom plate can move, The control unit a non-detection state in which neither the height detection unit nor the lowest height detection unit detects that the bottom plate or the seat is at a predetermined height, Before raising the bottom plate, the bottom plate is lowered until either the height detection unit or the lowest height detection unit detects that the bottom plate or the sheet is at a predetermined height. The sheet feeding device according to claim 6 .

9. The control unit the height detection units, excluding the uppermost height detection unit placed at a height position corresponding to the uppermost limit of the range in which the bottom plate can move, are in a detection state in which they detect that the bottom plate or the seat is at a predetermined height, Furthermore, when the lowest height detection unit is in a non-detection state where it does not detect that the bottom plate or the seat is at a predetermined height, Before raising the bottom plate, the bottom plate is lowered until the lowest height detection unit installed at the lowest position detects that the bottom plate or the sheet is at a predetermined height. The sheet feeding device according to claim 8 .

10. a bottom plate detector that detects the presence of the bottom plate between a top height detector, which is the height detector installed at the upper limit of the movement range of the bottom plate, and a height detector installed at the next height position after the top height detector; The control unit When none of the height detection units is in a non-detection state where it does not detect that the bottom plate or the seat is at a predetermined height, and the bottom plate detection unit is in a detection state where it detects the bottom plate, Before raising the bottom plate, the bottom plate is lowered until any one of the height detection units changes to a detection state that detects that the bottom plate is at a predetermined height. The sheet feeding device according to claim 6 .

11. an image forming device that forms an image on a sheet; An image forming system comprising: the sheet feeding device according to claim 1 that feeds the sheet to the image forming device.

Images