JP2013230877A - Sheet feeding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently raise/lower a low-speed sheet feeding table in supplying or replacing sheets.SOLUTION: Sheet feeding table sensors 19a to 19d each including a photo-interrupter are disposed at proper intervals on a moving path of a light shielding plate 18 that moves up/down together with a sheet feeding table 11, to detect the sheet feeding table 11 at an upper limit position of a moving range, at positions lowered from the upper limit position by 10%, by 30% and by 50%, and at a lower limit position, respectively. A stepwise descending amount of the sheet feeding table 11 is increased as it moves away from the upper limit position. Especially, an unnecessary descending degree of the sheet feeding table 11 is made relatively smaller as the number of sheets P to be supplied or replaced on the sheet feeding table 11 is smaller.

Description

  The present invention relates to a sheet feeding device that is connected to an image forming apparatus such as a printer or a printing apparatus and supplies stacked printing sheets to a sheet feeding position of the image forming apparatus.

  An external paper feeding device that supplies printing paper to the paper feeding position of the image forming apparatus continuously supplies a larger amount of paper used for printing by the image forming apparatus than the paper feeding tray of the image forming apparatus. Used in connection with a forming device.

  In this sheet feeding device, the sheet feeding table is moved up as the sheet is consumed in order to supply the top sheet stacked on the sheet feeding table to the sheet feeding position of the image forming apparatus. When replenishing paper to the paper feed tray, it is necessary to temporarily lower the paper feed stand to secure a paper replenishment space. The same need may arise when changing the paper to a different type in accordance with the changeover.

  By the way, in a paper feeding device that continuously supplies a large amount of paper, a considerable number of paper is stacked on the paper feed table (for example, in units of several thousand sheets). Therefore, the weight of the paper on the paper feed tray is considerable, and the torque required for the motor that raises and lowers the paper feed tray is also considerable. For this reason, in order to ensure torque, the lifting speed of the sheet feeding table must be slow to some extent.

  In consideration of this, the paper feed table may be lowered once to the lower limit position when paper is replenished or replaced. However, the paper feed platform should be moved down more clearly than necessary compared to the number of paper to be replenished or replaced. If possible, it is preferable to do so. Otherwise, the sheet feeding table must be raised and lowered more than necessary, including moving the sheet feeding table up so that the top sheet reaches the sheet feeding position of the image forming apparatus after replenishment or replacement. , There is a possibility that the wasteful time required for this will be a length that cannot be ignored.

  As a conventional proposal for a downward movement amount corresponding to the number of sheets to be replenished or replaced, there is a method in which the downward movement amount of the paper supply base in accordance with the user's switch operation is set at a constant pitch. In this proposal, every time the paper feed table is moved down a certain pitch, if the upper end of the paper on the paper feed table does not reach a certain height, further lowering of the paper feed table is prohibited ( For example, Patent Document 1).

JP 2010-89890 A

  However, in the above-described conventional proposal, since the paper feed table cannot be moved down unless the upper end of the paper on the paper feed tray reaches a certain height, the more sheets to be supplied or replaced, the more the paper feed stand. It is necessary to repeat the downward movement of the sheet and the replenishment of the sheet. Such a setup is not suitable for the user in a situation where the elevation speed of the sheet feed base must be set low in order to ensure torque.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a paper feeding device capable of efficiently raising and lowering a paper feeding table having a low elevation speed when replenishing or replacing paper. There is.

In order to achieve the above object, a paper feeding device according to the present invention described in claim 1 comprises:
Stops the downward movement of the paper feed table on which the paper to be supplied to the image forming apparatus is loaded, according to the generation of the downward movement request command, at a height corresponding to the mounting position of the paper feed sensor that detects the paper feed table. In the paper feeder,
The paper feed table sensor so that the interval between the positions where the lowering of the paper feed table is stopped in response to the generation of the down movement request command increases stepwise as it moves away from the upper limit position of the paper feed table. Are arranged,
It is characterized by that.

  According to the sheet feeding device of the present invention described in claim 1, as the interval between the positions where the lowering of the sheet feeding table is stopped due to the generation of the lowering request command is moved away from the upper limit position of the sheet feeding table. Increase in stages. For this reason, as the number of sheets to be replenished or replaced decreases, the lowering stop position of the sheet feed table is set at a relatively fine pitch. Therefore, in particular, the smaller the number of sheets to be replenished or replaced, the less the amount of lowering of the sheet feeding stand is necessary, and the sheet feeding stand having a low elevation speed is replenished or replaced. In this case, it can be lifted and lowered efficiently.

  According to a second aspect of the present invention, there is provided the paper feeding device according to the first aspect of the present invention, wherein the paper feeding table sensor is disposed on a lifting path of the paper feeding table. And a setting unit that sets valid / invalid of detection of the paper feed table for each of the paper feed table sensors, and is set as valid by the setting unit. The position at which the lowering of the paper feeding table is stopped due to the generation of the lowering request command is increased stepwise as the distance from the upper limit position of the paper feeding table is increased. It is characterized by being set at intervals.

  According to the sheet feeding device of the present invention described in claim 2, in the sheet feeding device of the present invention described in claim 1, the setting by the setting unit of the sheet feeding table sensor that enables the detection of the sheet feeding table, It is possible to arbitrarily set a position at which the lowering of the sheet feeding table is stopped in response to the generation of the lowering request command. For this reason, for example, the position of the sheet feeding table that is frequently used can be set to a position where the lowering of the sheet feeding table is stopped by setting the setting unit through the mounting position of the sheet feeding table sensor.

  Furthermore, the sheet feeding device of the present invention described in claim 3 is a remaining amount display for displaying the remaining amount of sheets stacked on the sheet feeding table in the sheet feeding device of the present invention described in claim 1 or 2. And a paper upper end sensor for detecting the upper end of the paper on the paper feed tray at the height of the paper supply to the image forming apparatus, and the remaining amount display means is configured to detect the paper supply by the paper upper end sensor. During the detection of the upper edge of the paper on the paper board, the content of the remaining amount to be displayed is determined based on the detection result of the paper feed board by the paper feed board sensor.

  According to the sheet feeding device of the present invention described in claim 3, in the sheet feeding device of the present invention described in claim 1 or 2, in a state where the sheets stacked on the sheet feeding table can be fed to the image forming apparatus. When the sheet feed table sensor detects the sheet feed table, the number of sheets on the sheet feed table can be estimated based on the known mounting position of the sheet feed table sensor. Therefore, the paper feed sensor can be effectively used not only for detecting the position of the paper feed stand but also for estimating the remaining number of sheets on the paper feed stand.

  According to a fourth aspect of the present invention, there is provided a paper feeding device according to the first aspect of the present invention, wherein the paper feeding device according to the first, second, or third aspect of the invention includes a paper sensor that detects the presence or absence of the paper on the paper feeding table. A designation unit that designates at least one of the plurality of paper feed table sensors, and the designation unit when the detection result of the paper on the paper feed table by the paper sensor is switched from yes to no. The apparatus further comprises command generation means for generating the downward movement request command to a height corresponding to the designated mounting position of the paper feed table sensor.

  According to the paper feeding device of the present invention described in claim 4, in the paper feeding device of the present invention described in claim 1, 2 or 3, when the paper on the paper feeding table runs out, Regardless of the user's switch operation, etc., it is automatically lowered until the paper feed table sensor designated by the designation means detects the paper feed table, and stopped at a height corresponding to the mounting position of the paper feed table sensor. . For this reason, for example, the position of the sheet feeding table that is frequently used can be set to a position where the downward movement of the sheet feeding table is stopped by the designation of the designation unit through the mounting position of the sheet feeding table sensor.

  According to the present invention, it is possible to efficiently raise and lower a paper feed table having a low elevation speed when paper is replenished or replaced.

1 is a perspective view showing a paper feeding device according to an embodiment of the present invention with a part cut away. It is a top view which shows schematic structure of the raising / lowering drive part which raises / lowers the paper feed stand of FIG. It is explanatory drawing which shows the raising / lowering drive part in the state which has the paper feed stand of FIG. 2 in a lower limit position from the side. FIG. 2 is an explanatory diagram illustrating a side view of the sheet feeding device in a state where the sheet feeding table of FIG. FIG. 2 is an explanatory diagram illustrating a side view of a sheet feeding device in a state in which the sheet feeding table of FIG. FIG. 3 is an explanatory view showing a part of the sheet feeding device in a state where the sheet feeding table in FIG. FIG. 2 is an explanatory view showing the sheet feeding device in a state where the sheet feeding table in FIG. FIG. 2 is an explanatory view showing the paper feeding device in a state where the paper feeding table in FIG. FIG. 2 is a block diagram illustrating an electrical schematic configuration of the sheet feeding device of FIG. 1. It is a flowchart which shows the procedure of the drive control of the drive motor which CPU of the control unit of FIG. 9 performs according to the program stored in the non-volatile memory.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, a sheet feeding device having a sheet feeding table that is driven and controlled by applying the sheet feeding table drive control device of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view showing a paper feeding device according to an embodiment of the present invention, with a part cut away. A sheet feeding device 1 according to the present embodiment illustrated in FIG. 1 has a rectangular frame-shaped casing 10, and a sheet feeding table 11 on which sheets P are stacked is installed inside the casing 10 so as to be movable up and down. ing. The paper feed tray 11 is formed in a rectangular shape using a rigid metal material or resin material so that, for example, about 4000 sheets of the same type of paper P can be stacked. The paper feed tray 11 is provided with a paper sensor 11 e that detects the presence or absence of the paper P on the paper feed tray 11.

  FIG. 2 is a plan view showing a schematic configuration of an elevating drive unit that elevates and lowers the paper feed table of FIG. A pair of left and right guide fences 12L and 12R for guiding the width direction of the paper P perpendicular to the transport direction of the paper P are provided on the upper surface 11a of the paper feed tray 11 shown in FIG. 2 via guide fence moving means (not shown). In this way, a large number of sheets of one type P such as A3 size, A4 size, and envelope size can be stacked.

  As shown in the explanatory view of FIG. 3 showing the elevation drive unit in a state where the sheet feed table 11 is at the lower limit position, a sheet feed roller 13 (pickup roller) and a separating roller are disposed above the sheet feed table 11. 14 is pivotally supported by a pair of left and right arms 15, 15, and both rollers 13, 14 can be rotated in the sheet conveying direction by a roller rotation drive source (not shown).

  Then, the paper feed roller 13 disposed on the upstream side in the transport direction of the paper P is in contact with the uppermost paper P stacked on the paper feed tray 11 while rotating, so that the uppermost paper P is transported in the transport direction. Paper is fed toward the downstream side.

  On the other hand, a friction plate 16 is attached to the separating roller 14 disposed on the downstream side of the sheet feeding roller 13, and the sheet P fed from the sheet feeding roller 13 is interposed between the separating roller 14 and the friction plate 16. While being nipped and conveyed, the sheets are separated one by one to prevent double feeding, and thereafter conveyed into the image forming apparatus 1.

  When the uppermost sheet P (the upper end of the sheet P on the sheet feeding table 10) comes into contact with the sheet feeding roller 13 and is ready to feed, the arm 15 is pushed up by the upper end of the sheet P together with the sheet feeding roller 13. It is done. Through the push-up of the arm 15, the paper upper end sensor 17 detects that the uppermost paper P is present at the supply height (supply position) to the image forming apparatus.

  Here, the elevating mechanism for elevating the paper feed tray 11 will be described. As shown in FIG. 2, in the elevating mechanism unit 20, a pair of left and right rack members 21 </ b> L and 21 </ b> R are attached in parallel to the housing 10 in order to raise and lower the paper feed table 11 in the vertical direction, The rack members 21L and 21R are formed so that the long rack teeth 21a are symmetrically toward the rear side of the paper feed table 11 installed between the two racks 21L and 21R.

  On the other hand, a plate-like bracket 22 is attached to the left side surface portion 11c on the front end portion 11b side of the paper feed table 11, and an L-shaped motor bracket 23 is attached to the right side surface portion 11d on the front end portion 11b side of the paper feed table 11. It has been. At this time, the L-shaped motor bracket 23 has a horizontal upper surface 23 a formed as a flat surface, and a vertical side surface 23 b fixed to the right side surface portion 11 d of the paper feed table 11.

  As shown in FIG. 3, a drive motor 24 as a drive source for raising and lowering the paper feed base 11 is vertically attached to the upper surface 23a formed on the right motor bracket 23 with the motor shaft 24a facing downward. The worm gear 25 is fixed to the motor shaft 24a.

  Further, as shown in FIG. 2, a stepped shaft 26 is laterally provided on the side surface 23 b orthogonal to the upper surface 23 a of the L-shaped motor bracket 23 toward the outside of the right side surface portion 11 d of the paper feed tray 11. The idler gear 27 attached to the stepped shaft 26 meshes with the worm gear 25 fixed to the motor shaft 24a as shown in FIG.

  Further, as shown in FIG. 2, a pair of left and right stepped shafts 28L and 28R are disposed at symmetrical positions on the side surface 23b of the left bracket 22 and the right motor bracket 23 toward the pair of left and right rack members 21L and 21R. Are disposed laterally toward the outer sides of the left side surface portion 11c and the right side surface portion 11d of the paper feed tray 11, and a pair of left and right pinion gears 29L and 29R are mounted on the pair of left and right stepped shafts 28L and 28R. . The pair of left and right pinion gears 29L and 29R mesh with the rack teeth 21a of the pair of left and right rack members 21L and 21R.

  At this time, the right pinion gear 29R meshes with the rack teeth 21a of the right rack member 21R, and also meshes with the idler gear 27 and is fixed to the motor shaft 24a by the drive motor 24. Although rotated, the left pinion gear 29L meshes only with the rack teeth 21a of the left rack member 21L.

  From the above, the pair of left and right rack members 21L and 21R are attached to the left and right sides of the housing 10, and the pair of left and right pinion gears 29L and 29R attached to the left and right sides of the paper feed base 11 are connected to the left and right pair of rack members 21L and 21R. By meshing with the rack teeth 21a, the paper feed table 11 can be lifted substantially horizontally without tilting left and right, and the lift operation of the paper feed table 11 equipped with the drive motor 24 is a pair of left and right. The rack members 21L and 21R are self-propelled via a pair of left and right pinion gears 29L and 29R.

  The sheet feeding table 11 of the sheet feeding apparatus 1 configured as described above is moved up and down between the upper limit position shown in the explanatory diagram of FIG. 4 and the lower limit position shown in the explanatory diagram of FIG. . In FIG. 4 and FIG. 5, the inner panel 10a exposed at the notched portion of the housing 10 is a base plate to which the rack members 21L, 21R and the like are attached. The paper feed table 11 is disposed on the back side of the inner panel 10a. Hereinafter, the configuration provided on the inner panel 10a will be described.

  In the following description, the operation on the left side of the paper feed tray 11 in FIG. 2 where the drive motor 24 is not attached will be mainly described. Further, the operation on the right side of the paper feed tray 11 provided with the drive motor 24 operates in the same manner in synchronism with the left side, and therefore will be basically omitted and will be described as necessary.

  As shown in FIG. 4 and FIG. 5, the pinion gear 29R and the stepped shaft 28R (not shown in FIG. 4 and FIG. 5) move up and down continuously with the sheet feed table 11 inside the slit 10b of the inner panel 10a. . Further, the light shielding plate 18 disposed in front of the slit 10 b (in front of the inner panel 10 a) is also moved up and down continuously with the paper feed table 11. On the ascending / descending path of the light shielding plate 18, paper feed table sensors 19 a to 19 d made of photo interrupters are arranged at intervals.

  FIG. 6 is an explanatory view showing the paper feeding device in a state where the paper feeding table in FIG. 1 is at a position lowered by 10% from the upper limit position, and is shown from the side. As shown in FIG. 6, the first and second sheet feed table sensors 19a and 19b from the top of the inner panel 10a are disposed on the light shielding plate 18 when the sheet feed table 11 is at a position lowered by 10% from the upper limit position. The upper end and the lower end are respectively attached to positions where detection light (not shown) is shielded.

  As is apparent from FIGS. 4 and 6, the first paper feed stand sensor 19 a from the top is located at any position between the upper limit position and the position where the paper feed stand 11 is lowered by 10% from the upper limit position. In addition, it is attached at a position where the detection light is shielded by the light shielding plate 18.

  FIG. 7 is an explanatory view showing the paper feeding device in a state in which the paper feeding table in FIG. As shown in FIG. 7, the second and third sheet feed table sensors 19b and 19c from the top of the inner panel 10a are disposed on the light shielding plate 18 when the sheet feed table 11 is at a position lowered by 30% from the upper limit position. The upper end and the lower end are respectively attached to positions where detection light (not shown) is shielded.

  That is, as apparent from FIGS. 6 and 7, the second paper feed stand sensor 19 b from the top is between the position where the paper feed stand 11 is lowered by 10% from the upper limit position and the position where it is lowered by 30% from the upper limit position. At any position, the light shielding plate 18 is attached to a position where the detection light is shielded.

  FIG. 8 is an explanatory view showing the paper feeding device in a state where the paper feeding table in FIG. 1 is at a position lowered by 50% from the upper limit position, and is shown from the side. As shown in FIG. 8, the third paper feed table sensor 19c from the top of the inner panel 10a is configured such that when the paper feed table 11 is at a position lowered by 50% from the upper limit position, the upper end of the light shielding plate 18 is detected light ( (Not shown) is attached at a position where light is shielded.

  That is, as apparent from FIGS. 7 and 8, the third paper feed stand sensor 19c from the top is between the position where the paper feed stand 11 is lowered 30% from the upper limit position and the position where the paper feed stand 11 is lowered 50% from the upper limit position. At any position, the light shielding plate 18 is attached to a position where the detection light is shielded.

  As is clear from FIG. 8, the lowermost sheet feeder sensor 19d has a lower end of the light shielding plate 18 that shields detection light (not shown) when the sheet feeder platform 11 is at the lower limit position. When the paper feed tray 11 is located at a position other than the lower limit position, the light shielding plate 18 is attached at a position where the light shielding plate 18 does not shield the detection light (not shown).

  Therefore, in a state where only the detection light of the first paper feed table sensor 19a from the top is blocked by the light shielding plate 18, the paper feed table 11 is between the upper limit position and a position that is 10% lower than the upper limit position. Existing. Further, in a state where the detection light of the first and second paper feed table sensors 19a and 19b from the top is shielded by the light shielding plate 18, the paper feed platform 11 exists at a position that is 10% lower than the upper limit position.

  Further, in a state where only the second paper feed table sensor 19b from the top is shielded by the light shielding plate 18, the paper feed table 11 is slightly below the position where it is lowered by 10% from the upper limit position, and is the position where it is lowered by 30% from the upper limit position. It exists between a little before. Further, in a state where the detection light of the second and third paper feed table sensors 19b and 19c from the top is shielded by the light shielding plate 18, the paper feed platform 11 exists at a position lowered by 30% from the upper limit position.

  Further, in a state where only the third sheet feed table sensor 19c from the top is shielded by the light shielding plate 18, the sheet feed table 11 is located slightly below the position where it is lowered by 30% from the upper limit position and at a position where it is lowered by 50% from the upper limit position. Exists between. Further, in a state where none of the detection lights of all the sheet feeding table sensors 19a to 19d are shielded by the light shielding plate 18, the sheet feeding table 11 is slightly below the position where it is lowered by 50% from the upper limit position and before the lower limit position. Exists in between.

  As shown in FIGS. 4 to 8, the inner panel 10a is formed with an insertion hole 10c for a stopper shaft (not shown). As shown in FIG. 6, the insertion hole 10 c is formed on the right side surface portion 11 d of the sheet feeding table 11 disposed on the back side of the inner panel 10 a when the sheet feeding table 11 is at a position lowered by 10% from the upper limit position. It is formed at a position overlapping with the insertion hole 11f.

  Therefore, when the paper feed tray 11 is at a position that is 10% lower than the upper limit position, a stopper shaft (not shown) is inserted into the insertion holes 10c and 11f of the inner panel 10a and the paper feed tray 11 to thereby drive the drive motor 24. Even in a free state, the paper feed tray 11 can be fixed so that it cannot be raised or lowered.

  Further, as shown in FIGS. 6 to 8, the paper upper end sensor 17 detects the upper end of the paper P on the paper supply base 11 when the paper supply base 11 is lowered by 10%, 30%, and 50% from the upper limit position, respectively. As a guide, dozens of sheets, 1000 sheets, and 2000 sheets of paper P can be stacked until no more sheets P can be stacked.

  Next, the electrical configuration of the sheet feeding device 1 of the present embodiment will be described with reference to the block diagram of FIG. The sheet feeding device 1 of the present embodiment has a control unit 50 for overall control. The control unit 50 executes various control processes by causing the CPU 51a to execute a program stored in a nonvolatile memory 51c including a ROM or a flash memory while using a work area of the volatile memory 51b including a RAM. To do.

  The CPU 51a is connected to a paper sensor 11e, a paper upper limit sensor 17, and paper feed table sensors 19a to 19d via a sensor interface (sensor I / F) 51d. Further, a motor driver 51f of the drive motor 24 is connected to the CPU 51a via a driver interface (driver I / F) 51e. Further, the CPU 51a is connected to the switches 10d and 10e for raising and lowering the sheet feed table 11 provided in the casing 10 of the sheet feeding device 1 and the remaining amount display indicator 10f via the other interface (other I / F) 51g. (See FIG. 1 for both).

  Note that the remaining amount indicator 10f shown in FIG. 1 indicates the remaining amount of sheets stacked on the sheet feed tray 11 according to a numerical range (for example, 2000 sheets or more, 1000 to 2000 sheets, 50 to 1000 sheets, 50 sheets or less). To display.

  Further, an input unit 52 and an output unit 53 are connected to the control unit 50 of FIG. The input unit 52 is a keyboard, a mouse, or the like, and performs various inputs. The output unit 53 is a display or a printer, and outputs the input content of the input unit 52 for confirmation.

  In the present embodiment, the stop position for automatically lowering the paper feed tray 11 when the paper P on the paper feed tray 11 runs out is designated from the input unit 52 as a position lowered by 50% from the upper limit position. It is assumed that the input is performed and stored in the nonvolatile memory 51c.

  Next, the drive control procedure of the drive motor 24 executed by the CPU 51a of the control unit 50 of FIG. 9 according to the program stored in the nonvolatile memory 51c will be described with reference to the flowchart of FIG.

  First, the CPU 51a checks whether or not the paper sensor 11e has detected that the paper P on the paper feed tray 11 has run out (step S1). If it is not detected that the paper P is on the paper feed tray 11 (NO in step S1), the process proceeds to step S5 described later.

  If it is detected that the paper P on the paper feed tray 11 is out of paper (YES in step S1), the CPU 51a feeds the paper to a position higher than the stop position stored in the non-volatile memory 51c (a position lowered by 50% from the upper limit position). Only when the table 11 is located, the sheet feeding table 11 is lowered to the stop position stored in the nonvolatile memory 51c (step S3). Thereafter, the CPU 51a ends the series of processes and causes the processes from step S1 to be executed again.

  In step S1, the CPU 51a checks whether or not the ascent switch 10d has been operated in step S5, which proceeds to (N) when it is not detected that the paper P on the paper feed tray 11 has been detected. If the raising switch 10d is not operated (NO in step S5), the process proceeds to step S9 described later. When the raising switch 10d is operated (YES in step S5), the CPU 51a moves the sheet feeding table 11 to the upper limit position (FIG. 4) unless the sheet upper edge sensor 17 detects the upper edge of the sheet P on the sheet feeding table 11. (Step S7). Thereafter, the CPU 51a ends the series of processes and causes the processes from step S1 to be executed again.

  In step S5, the CPU 51a confirms whether or not the lowering switch 10e has been operated in step S9 which proceeds to the case where the up switch 10d has not been operated (N). When the descent switch 10e is not operated (NO in step S9), the process proceeds to step S15 described later.

  When the descent switch 10e is operated (YES in Step S9), the CPU 51a specifies the position or range where the paper feed tray 11 exists from the detection patterns of the paper feed stand sensors 19a to 19d (Step S11), and sets the upper limit position. Then, the paper feed table 11 is lowered to the nearest position among the position lowered by 10%, the position lowered by 30%, the position lowered by 50%, and the lower limit position (step S13). Thereafter, the CPU 51a ends the series of processes and causes the processes from step S1 to be executed again.

  In step S9, the CPU 51a checks whether or not the upper edge of the paper P is detected by the CPU 51a in step S15 which proceeds to the case where the lowering switch 10e is not operated (N). When the upper end sensor 17 of the sheet detects the upper end of the sheet P (YES in step S15), the CPU 51a ends the series of processes and causes the processes from step S1 to be executed again.

  If the sheet upper end sensor 17 has not detected the upper end of the sheet P (NO in step S15), the paper feed base 11 is raised until the sheet upper end sensor 17 detects the upper end of the sheet P (step S17). Then, the CPU 51a identifies the position or range where the paper feed tray 11 exists from the detection patterns of the paper feed tray sensors 19a to 19d (step S19), and based on the identified result, the remaining amount of paper P on the paper feed tray 11 Alternatively, the range is estimated (step S21).

  And CPU51a updates the display of the residual amount display indicator 10f of the housing | casing 10 to the content corresponding to the estimated residual amount or its range (step S23). Thereafter, the CPU 51a returns the process to step S15.

  As is clear from the above description, in the present embodiment, the remaining amount display indicator 10f and the control unit 50 constitute the remaining amount display means in the claims. In the present embodiment, the control unit 50 constitutes the specifying means in the claims. Furthermore, in this embodiment, step S3 in the flowchart of FIG. 10 is a process corresponding to the command generation means in the claims.

  In the sheet feeding device 1 of the present embodiment described above, when the lowering switch 10e is operated, the sheet feeding table 11 exists between the upper limit position and a position in front of the position that is 10% lower than the upper limit position. When it is, the paper feed tray 11 is lowered to a position where it is lowered by 10% from the upper limit position. Further, when the paper feed tray 11 exists between a position where it is lowered by 10% from the upper limit position and a position before the position where it is lowered by 30% from the upper limit position, the paper feed stand 11 is lowered to a position where it is lowered by 30% from the upper limit position. Falls.

  Further, when the paper feed tray 11 is present between a position where it is lowered 30% from the upper limit position and a position before the position where it is lowered 50% from the upper limit position, the paper feed stand 11 is lowered to a position where it is lowered 50% from the upper limit position. Falls. Further, when the paper feed tray 11 exists between a position where it is lowered by 50% from the upper limit position and slightly before the lower limit position, the paper feed tray 11 is lowered to the lower limit position.

  Therefore, for example, when the paper feed tray 11 exists at the upper limit position, the operation of the lowering switch 10e is repeated, so that the paper feed tray 11 is lowered by 10% from the upper limit position, and is lowered by 30% from the upper limit position. Then, it descends step by step to a position lower by 50% from the upper limit position and to a lower limit position.

  The stepwise lowering amount of the paper feed tray 11 increases as the distance from the upper limit position increases. In particular, the smaller the number of sheets P to be replenished or replaced, the more the paper feed tray 11 becomes more than necessary. The degree of descent is relatively reduced. For this reason, even when the ascending / descending speed of the paper feed tray 11 by the drive motor 24 is low, the degree to which the paper feed tray 11 is lowered more than necessary when the paper P of the paper feed tray 11 is replenished or replaced is reduced. Can be lowered efficiently.

  That is, for example, in a state where the paper P is stacked on the paper feed tray 11, the lower the paper feed tray 11 is located near the upper limit position, the lower the amount of the paper feed tray 11 lowered by the operation of the lowering switch 10e. Therefore, when the number of sheets P to be replenished or replaced is small, the sheet feed table 11 can be lowered at a short pitch by operating the descent switch 10e a small number of times.

  Further, as the number of operations of the lowering switch 10e increases, the lowering pitch of the paper feed tray 11 becomes larger. Therefore, when the number of sheets P to be replenished or replaced is large, the number of times is proportional to the number of sheets P to be replenished or replaced. By operating the lowering switch 10e a small number of times, the sheet feeding table 11 can be lowered more than a necessary amount.

  And, as described above, the increase / decrease of the lowering amount of the paper feed tray 11 according to the number of sheets P to be replenished or replaced can be realized without requiring to use a different switch for each lowering amount. The burden on the user can be reduced.

  Further, in the present embodiment, when the paper feed tray 11 exists at a position 10% lower than the upper limit position, a stopper shaft (not shown) is inserted into the insertion holes 10c and 11f of the inner panel 10a and the paper feed tray 11. Thus, even when the drive motor 24 is in a free state, the paper feed tray 11 can be fixed so that it cannot be raised or lowered. For this reason, the position at which the sheet feeding table 11 is fixed so that it cannot be moved up and down during maintenance of the sheet feeding device 1 can be set as a step-down stop position of the sheet feeding table 11.

  In the present embodiment, when the paper P on the paper feed tray 11 runs out of paper, the stop position (a position lowered by 50% from the upper limit position) stored in the nonvolatile memory 51c can be used without operating the lowering switch 10e. The sheet feeding table 11 is automatically lowered. However, even when the paper P is out of paper, the paper feed tray 11 may be lowered by operating the lowering switch 10e. In that case, step S1 and step S3 in the flowchart of FIG. 10 may be omitted.

  Further, in the present embodiment, a case has been described in which all the paper feed table sensors 19a to 19d correspond to paper feed table sensors that effectively detect the paper feed table in the claims. However, a part of the paper feed base sensors may be configured to be able to set that the paper feed base sensor 11 does not detect the paper feed base 11 effectively (invalid).

  In that case, an input for setting the paper feed table sensors 19a to 19d to be invalidated is made from the input unit 52 and stored in the nonvolatile memory 51c. Therefore, the control unit 50 constitutes the setting means in the claims.

  For example, the second paper feed sensor 19b from the top is set to be invalid, and the position at which the lowering of the paper feed board 11 due to the operation of the lowering switch 10e is stopped is 10% lower than the upper limit position, from the upper limit position. You may make it limit to the position which fell 50%, and the lower limit position.

  In this case, the fact that the paper feed tray 11 has reached a position that is 10% lower than the upper limit position indicates that the detection light of the first paper feed stand sensor 19a from the top is not shielded by the light shielding plate 18 and is 2 from the top. Since the detection light of the third sheet feeding table sensor 19b has shifted from the state where it is blocked by the light shielding plate 18 to the state where it is not blocked, it is possible to detect without using the output of the third sheet feeding table sensor 19c from the top. it can.

  The sheet feed table 11 existing between a position 10% lower than the upper limit position and a position 50% lower than the upper limit position, a little lower than the position 50% lower than the upper limit position, and the lower limit position The sheet feeding table 11 existing before the sheet feeding table 11 also depends on the output patterns of the first, second, and lowest sheet feeding table sensors 19a, 19b, 19d that are not set to be invalid. Thus, the detection can be made without using the output of the third paper feed table sensor 19c from the top.

  Note that, by disabling the second paper feed table sensor 19b from the top, the CPU 51a of the control unit 50 in step S11 and step S19 in the flowchart of FIG. It is impossible to specifically specify that the sheet feed table 11 exists in the range.

  For this reason, for example, in step S13, the CPU 51a disables the second paper feed table sensor 19b from the top and becomes undetectable, and removes the position 30% below the upper limit position to the nearest position to the paper feed table. 11 can be lowered. In step S21, the CPU 51a may estimate the remaining amount (or remaining amount range) of the paper P on the paper feed table 11 that can be specified by the output patterns of the paper feed sensors 19a, 19b, and 19d.

  Further, the display of the remaining amount (or range) of the paper P on the paper feed tray 11 by the remaining amount display indicator 10f of the housing 10 may be omitted. However, as in the present embodiment, the remaining amount (or range) of the paper P on the paper feed tray 11 is estimated from the output patterns of the paper feed tray sensors 19a to 19d and displayed on the remaining amount display indicator 10f. This is advantageous because the sheet feed sensors 19a to 19d can be effectively used for purposes other than detecting the position of the sheet feed table 11.

DESCRIPTION OF SYMBOLS 1 Paper feeder 10 Case 10a Inner panel 10b Slit 10c, 11f Insertion hole 10d Up switch 10e Down switch 10f Remaining amount indicator 11 Paper feed stand 11a Top surface 11b Tip part 11c Left side part 11d Right side part 11e Paper sensor 12L, 12R Guide fence 13 Paper feed roller 14 Rolling roller 15, 15 Arm 16 Friction plate 17 Paper upper end sensor 18 Shading plate 19a-19d Paper feed base sensor 20 Lifting mechanism 21L, 21R Rack member 21a Rack tooth 21b Outer side surface 22 Bracket 23 Motor bracket 23a Upper surface 23b Side surface 24 Drive motor 24a Motor shaft 24b Encoder 25 Worm gear 26 Shaft 27 Idler gear 28L, 28R Shaft 29L, 29R Pinion gear 50 Control unit 5 a CPU
51b Volatile memory 51c Non-volatile memory 51d Sensor interface 51e Driver interface 51f Motor driver 51g Switch interface 52 Input section 53 Output section P Paper

Claims (4)

Stops the downward movement of the paper feed table on which the paper to be supplied to the image forming apparatus is loaded, according to the generation of the downward movement request command, at a height corresponding to the mounting position of the paper feed sensor that detects the paper feed table. In the paper feeder,
The paper feed table sensor so that the interval between the positions where the lowering of the paper feed table is stopped in response to the generation of the down movement request command increases stepwise as it moves away from the upper limit position of the paper feed table. Are arranged,
A paper feeder characterized by that.   A predetermined number of the paper feed base sensors are arranged on the lift path of the paper feed base at intervals in the vertical direction of the paper feed base, and the detection of the paper feed base is effective for each paper feed base sensor. And setting means for setting invalidity, and the lowering of the sheet feeding table accompanying the generation of the lowering request command is stopped by the plurality of sheet feeding table sensors set to be valid by the setting means. The sheet feeding device according to claim 1, wherein the position is set at an interval that increases stepwise as the position moves away from the upper limit position of the sheet feeding table.   A remaining amount display unit configured to display a remaining amount of sheets stacked on the sheet feed table; and a sheet upper end sensor configured to detect a sheet upper end on the sheet feed table at a sheet supply height to the image forming apparatus. The remaining amount display means is configured to display the remaining amount based on a detection result of the paper feed table by the paper feed table sensor during detection of the upper end of the paper on the paper feed table by the paper upper end sensor. 3. The sheet feeding device according to claim 1, wherein the content of the amount is determined.   A paper sensor for detecting the presence or absence of the paper on the paper feed table, a designation means for designating at least one of the plurality of paper feed sensors, and a paper sensor on the paper feed table by the paper sensor. And a command generation means for generating the down movement request command to a height corresponding to the mounting position of the paper feed table sensor designated by the designation means when the detection result is switched from presence to absence. The paper feeding device according to claim 1, 2, or 3.

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