JP2017149549A - Paper feeding device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeding device capable of shortening waiting time during replenishment of recording paper.SOLUTION: A paper feeding device 6 includes: a loading plate 61 and a lifting mechanism which vertically moves the loading plate 61. The paper feeding device further includes: an upper side distance measuring sensor 66; a lower side distance measuring sensor 67; a distance speed table in which a maximum moving speed of the loading plate 61 is set together with slow-down information; and a lifting control section which starts lowering of the loading plate 61 at the maximum moving speed by the lifting mechanism when a lowering instruction is input, stops the loading plate 61 at a lower limit position on the basis of the lower side distance measured by the lower side distance measuring sensor 67 and the slow-down information, starts lifting of the loading plate 61 at the maximum moving speed by the lifting mechanism when a lifting instruction is input, and stops the loading plate 61 so that loaded recording paper P at an uppermost section is located at a paper feed position on the basis of the upper side distance measured by the upper side distance measuring sensor 66 and the slow-down information.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sheet feeding device and an image forming apparatus including a stacking plate on which recording paper is stacked and an elevating mechanism that moves the stacking plate in the vertical direction.

  An image forming apparatus such as a copying machine, a facsimile machine, or a multifunction machine is configured to record a formed image on a recording sheet fed from a paper feeding device. The sheet feeding device includes a stacking plate on which a plurality of recording sheets are stacked, and is generally fed out from the upper surface side of the plurality of recording sheets stacked on the stacking plate. Therefore, a technique has been proposed that includes an elevating mechanism that moves the stacking plate in the vertical direction, and maintains the upper surface position of the recording paper at the paper feeding position by the elevating mechanism (see, for example, Patent Document 1).

JP 2003-48635 A

  However, in the case of a large-capacity paper feeding device having a large number of recording paper sheets, the moving distance of the loading plate is several tens of centimeters, and the weight of the recording paper to be loaded is several kilograms to several tens of kilograms. For this reason, the moving speed of the stacking plate is set as slow as several centimeters / second, and it takes from ten or more seconds to move the stacking plate, which has been used up almost to the recording paper and moved to the upper limit position, to the lower limit position for supplying the recording paper It takes tens of seconds. This time is not a short time for a user who is replenishing paper. If there is a small amount of recording paper replenished, it takes time to move the stacking plate to the paper feeding position, which further imposes a waiting time on the user.

  SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a paper feeding device and an image forming apparatus that can solve the problems of the prior art and reduce the waiting time when replenishing recording paper.

The paper feeding device of the present invention is a paper feeding device comprising a stacking plate on which recording paper is stacked and an elevating mechanism for moving the stacking plate in the vertical direction, and the recording paper stacked on the stacking plate. An upper distance measuring sensor for measuring an upper distance from the uppermost recording paper stacked on the stacking plate and a lower position of the lower limit position of the stacking plate. A lower distance measuring sensor for measuring a lower distance between the loading plate and a maximum moving speed of the loading plate when the loading plate is gradually lowered from the maximum moving speed to a stop state. When a distance speed table set together with slowdown information defining a process and a lowering instruction are input, the lifting mechanism starts to descend at the maximum moving speed by the elevating mechanism, and the lower distance measuring sensor The lower side to be measured Based on the separation and the slowdown information, the loading plate is stopped at the lower limit position, and when an ascending instruction is input, the lifting mechanism starts to raise the loading plate at the maximum moving speed, and the upper side And an elevating control unit for stopping the stacking plate so that the uppermost recording paper stacked is in a paper feed position based on the upper distance measured by the distance measuring sensor and the slowdown information. It is a feature.
Further, in the sheet feeding device according to the present invention, in the distance speed table, the maximum moving speed is set to a faster value as the loading amount is smaller in accordance with the loading amount of the recording paper loaded on the loading plate. When the lowering instruction or the ascending instruction is input, the elevation control unit calculates the load amount based on the upper distance and the lower distance, and the lift control unit according to the calculated load amount The loading plate may be moved at the maximum moving speed.
Further, in the paper feeder of the present invention, in the distance speed table, the slowdown information is defined by a deceleration, and the deceleration is in accordance with a load amount of the recording paper loaded on the stacking plate. The smaller the loading amount, the larger the value may be set.
Furthermore, in the sheet feeding device of the present invention, in the distance speed table, the maximum moving speed is set to a value that is faster to descend than to rise according to the moving direction of the stacking plate. The unit may move the stacking plate at the maximum moving speed according to a moving direction of the stacking plate when the lowering instruction or the raising instruction is input.
Further, in the sheet feeding device according to the present invention, the distance speed table is set with slow-up information defining a deceleration process when the stacking plate is gradually raised from a stopped state to the maximum moving speed, and the elevation control is performed. The unit may start moving the stacking plate based on the slow-up information when the lowering instruction or the raising instruction is input.
According to another aspect of the present invention, there is provided an image forming apparatus including: the above-described paper feeding device; and an image forming unit that records the formed image on the recording paper fed from the paper feeding device.

  According to the present invention, the maximum moving speed can be set fast by performing slow-down control of the stacking plate 61 while measuring the height position of the stacking plate 61 and the position of the recording paper P (top). The rise / fall time can be shortened. As a result, there is an effect that the waiting time at the time of supplying the recording paper, that is, the waiting time when the recording paper is supplied to the stacking plate and the waiting time after the supplying can be shortened.

1 is a schematic cross-sectional view illustrating a configuration example of an image forming apparatus in which an embodiment of a paper feeding device according to the present invention is mounted. It is a figure which shows the positional relationship of the upper range sensor and lower range sensor shown in FIG. FIG. 2 is a block diagram illustrating a hardware configuration of the image forming apparatus illustrated in FIG. 1. It is a figure which shows the distance speed table example shown in FIG. It is a flowchart which shows the example of movement control at the time of the fall by the raising / lowering control part shown in FIG. It is a flowchart which shows the example of movement control at the time of the raise by the raising / lowering control part shown in FIG.

Next, embodiments of the present invention will be specifically described with reference to the drawings.
The image forming apparatus 1 according to the present embodiment is a copying machine, and includes a document reading unit 2, a document feeding unit 3, and a recording unit 4, as shown in FIG. The document reading unit 2 is disposed above the recording unit 4, and the document feeding unit 3 is disposed above the document reading unit 2. Although the image forming apparatus 1 of the present embodiment has been described with reference to a copying machine, it is needless to say that a facsimile machine, a multifunction machine, and the like are included.

  On the front side of the image forming apparatus 1, an operation unit 5 for setting the image forming apparatus 1 and operating instructions is disposed. The operation unit 5 includes a display unit for displaying various operation keys for accepting operation inputs, a numeric keypad for inputting numerical values such as the number of prints, a reset key for inputting an instruction to initialize setting information, and a copying operation. Or a permanent key such as a stop key for erasing input numerical values and a start key for inputting an output instruction for starting a printing operation.

  Referring to FIG. 1, the document reading unit 2 includes a scanner 21, a platen glass 22, and a document reading slit 23. The scanner 21 includes an exposure lamp, a CCD (Charge Coupled Device) sensor, and the like, and is configured to be movable in the conveyance direction of the document MS by the document feeding unit 3. The platen glass 22 is an original table made of a transparent member such as glass. The document reading slit 23 has a slit formed in a direction orthogonal to the direction in which the document MS is conveyed by the document feeding unit 3.

  When reading the document MS placed on the platen glass 22, the scanner 21 is moved to a position facing the platen glass 22 and reads the document MS while scanning the document MS placed on the platen glass 22. Image data is acquired, and the acquired image data is output to the recording unit 4. When reading the document MS conveyed by the document feeding unit 3, the scanner 21 is moved to a position facing the document reading slit 23, and the document MS by the document feeding unit 3 is moved through the document reading slit 23. The document MS is read in synchronism with the transport operation to acquire image data, and the acquired image data is output to the recording unit 4.

  The document feeding unit 3 includes a document placement unit 31, a document transport mechanism 32, and a document discharge unit 33. The documents MS placed on the document placement unit 31 are sequentially fed out one by one by the document conveyance mechanism 32 and conveyed to a position facing the document reading slit 23 of the document reading unit 2, and then the document discharge unit. It is discharged to 33. The document feeding unit 3 is configured to be retractable, and the upper surface of the platen glass 22 can be opened by lifting the document feeding unit 3 upward.

The recording unit 4 includes an image forming unit 40, and includes a paper feeding device 6 and a transport unit 7.
The paper feeding device 6 includes a stacking plate 61 on which the recording paper P is stacked, a wire 62 that is a lifting mechanism for moving the stacking plate 61 in the vertical direction, a pulley 63, a driving pulley 64, a lifting motor 65, and an upper distance measuring sensor. 66 and a lower distance measuring sensor 67.

  The wires 62 are fixed to both ends of the stacking plate 61. Then, by rotating the driving pulley 64 forward and backward by the lifting motor 65, the wire 62 is driven through the pulley 63, and the stacking plate 61 is moved in the vertical direction. Note that the paper feeding device 6 is not limited to this configuration, and the lifting mechanism ahead of the lifting motor 65 can use a gear, a lifting belt, or the like.

The upper distance measuring sensor 66 is disposed above the feeding position of the recording paper P stacked on the stacking plate 61, and determines the upper distance D _up between the uppermost recording paper P stacked on the stacking plate 61. taking measurement. The lower distance measuring sensor 67 is disposed below the lower limit position of the stacking plate 61 and measures the lower distance D _down with _respect to the stacking plate 61. The upper distance measuring sensor 66 and the lower distance measuring sensor 67 may be optical or ultrasonic. In the present embodiment, as shown in FIG. 2A, the distance between the upper distance measuring sensor 66 (measurement surface thereof) and the paper feed position, that is, the uppermost recording paper P stacked on the stacking plate 61. 2 is an upper distance D _up in the case of the paper feed position, and as shown in FIG. 2B, the lower distance measuring sensor 67 (the measurement surface thereof) and the lower surface of the stacking plate 61 (the lower surface thereof). ), That is, the lower distance D _down when the stacking plate 61 is at the lower limit position is “Y”. The height of the recording sheet P loaded on the stacking plate 61 is “3H”, and the distance between the upper distance measuring sensor 66 (its measurement surface) and the lower distance measuring sensor 67 (its measurement surface) is , “Z”.

  The transport unit 7 includes a paper feed roller 71, a transport roller 72, and a discharge roller 73. The paper feeding device 6 moves the uppermost recording paper P stacked on the stacking plate 61 to the paper feeding position by the lifting mechanism, and the paper feeding roller 71 moves the uppermost recording paper P from the paper feeding device 6 to the transport path. Pull out. The recording paper P fed out by the paper supply roller 71 is conveyed to the image forming unit 40 by the conveyance roller 72. Then, the recording paper P on which recording has been performed by the image forming unit 40 is guided to the discharge roller 73 and output to the discharge tray 8.

  The image forming unit 40 includes a photosensitive drum 41, a charging unit 42, an exposure unit 43, a developing unit 44, a transfer unit 45, a cleaning unit 46, and a fixing unit 47. The exposure unit 43 is an optical unit including a laser device, a mirror, and the like. The exposure unit 43 outputs laser light based on image data, exposes the photosensitive drum 41 charged by the exposure unit 43, and An electrostatic latent image is formed on the surface. The developing unit 44 is a developing unit that develops the electrostatic latent image formed on the photosensitive drum 41 using toner, and forms a toner image based on the electrostatic latent image on the photosensitive drum 41. The transfer unit 45 transfers the toner image formed on the photosensitive drum 41 by the developing unit 44 onto the recording paper P. The fixing unit 47 heats the recording paper P onto which the toner image has been transferred by the transfer unit 45 to fix the toner image on the recording paper P.

Next, a hardware configuration example of the image forming apparatus 1 will be described with reference to FIG.
The document reading unit 2, the document feeding unit 3, and the operation unit 5 of the image forming apparatus 1, and the image forming unit 40, the sheet feeding device 6, and the transport unit 7 that constitute the recording unit 4 are connected to the main control unit 9. The operation is controlled by the main controller 9. The main control unit 9 is connected to a storage unit 10, an image processing unit 11, and a cover opening / closing sensor 12.

  The main control unit 9 is an information processing unit such as a microcomputer including a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The ROM stores a control program for controlling the operation of the image forming apparatus 1. The CPU of the main control unit 9 reads the control program stored in the ROM and develops the control program in the RAM, thereby controlling the entire apparatus according to predetermined instruction information input from the operation unit 5. .

  The storage unit 10 is a storage unit such as a semiconductor memory or an HDD (Hard Disk Drive), and image data acquired by reading a document by the document reading unit 2 or an image received from a peripheral device via a communication unit (not shown). Data is stored.

  The image processing unit 11 is a unit that performs predetermined image processing on image data. For example, image improvement processing such as enlargement / reduction processing, density adjustment, and gradation adjustment is performed.

  The cover opening / closing sensor 12 is a sensor that detects opening / closing of a supply cover (not shown) that covers the stacking plate 61 of the sheet feeding device 6. The user opens the supply cover to supply the recording paper P to the stacking plate 61, and closes the supply cover when the supply of the recording paper P is completed. Accordingly, when the main control unit 9 recognizes that the replenishment cover is opened based on the cover opening information from the cover opening / closing sensor 12, the main control unit 9 instructs the sheet feeding device 6 to move to the lower limit position of the stacking plate 61. Is output. When the main control unit 9 recognizes that the replenishment cover is closed based on the cover closing information from the cover opening / closing sensor 12, the main control unit 9 sets the uppermost recording paper P stacked on the stacking plate 61 to the paper feeding device 6. An ascending instruction for instructing movement to the paper feed position is output.

The sheet feeding device 6 includes a lift control unit 68 and a distance speed table 69.
When a lowering instruction is input from the main control unit 9, the elevating control unit 68 drives the elevating motor 65 to lower (move) the stacking plate 61 to the lower limit position, and an up instruction is input from the main control unit 9. Then, the elevating motor 65 is driven to raise (move) the uppermost recording paper P stacked on the stacking plate 61 to the paper feeding position. The lift control unit 68 is loaded on the loading plate 61 based on the upper distance D _up measured by the upper distance measuring sensor 66 and the lower distance D _down measured by the lower distance measuring sensor 67. The loading amount of the recording paper P is determined. In the present embodiment, the elevation control unit 68 determines the loading amount of the recording paper P based on the height h of the recording paper P that has been stacked, It is discriminated between “middle” where the height h is H or more and less than 2H and “many” where the height h is 3H or more and 3H or less. Further, the up / down control unit 68 determines the stacking amount of the recording sheet P, the distance / speed table 69, the upper distance D _up measured by the upper distance measuring sensor 66, or the lower side measured by the lower distance measuring sensor 67. Based on the distance D _down , the current (or clock frequency) to the lifting motor is controlled to control the moving speed of the stacking plate 61.

In the distance speed table 69, as shown in FIG. 4, the maximum moving speed V _mn (m = aorb, n = 1 or 2 or 3) of the stacking plate 61, slow-up information, and slow-down information are displayed in the moving direction (down, For each loading amount (“small”, “medium”, “many”) of the recording paper P determined by the elevation control unit 68. The slow-up information is information that defines the acceleration process when the moving speed of the stacking plate 61 is gradually increased from the stopped state to the maximum moving speed _Vmn by the relationship between the distance and the speed. The distance to reach the moving speed V _mn is defined as the maximum moving speed reach distance D _smn . The slow-down information is information that defines the deceleration process when gradually reducing the speed of the stacking plate 61 from the maximum movement speed V _mn to the stop state in relation to the distance and speed, and the loading of the maximum movement speed V _mn is performed. The distance required until the plate 61 is stopped is defined as the deceleration start distance _Demn .

In the distance speed table 69, when the movement direction is the same, the maximum movement speed V _mn with the load amount “medium” is set faster than the maximum movement speed V _mn with the load amount “high”, and the load amount is “medium”. The maximum movement speed V _{mn with} a load amount “smaller” than the maximum movement speed V _mn is set to be faster (V _a3 <V _a2 <V _a1 , V _b3 <V _b2 <V _b1 ). That is, the loading amount of the recording paper P is proportional to its weight. Accordingly, the smaller the load amount, the smaller the required torque of the lifting motor 65 may be. Therefore, the smaller the load amount, the faster the maximum movement speed V _mn is set.

Further, the distance speed table 69, if the load weight is the same, the maximum moving speed _{V mn} during descent than the maximum moving speed _{V mn} at elevated is set faster _{(V a3> V b3, V} a2> V _b2 , V _a1 > V _b1 ). That is, the weight of the recording paper P acts as a negative force when rising, whereas the weight of the recording paper P acts as a positive force when descending. Accordingly, since the required torque of the lifting motor 65 may be smaller when the moving direction is lower than the rising direction, the maximum moving speed V _{mn for} lowering is set faster than the rising.

In the present embodiment, the loading amount of the recording paper P is determined in three stages, but it may be determined in two stages or four or more stages. The maximum moving speed V _mn may be calculated based on the calculated height h of the recording paper P and the moving direction.

Further, in this embodiment, the slow-up information and the slow-down information are defined by the relationship between the distance and the speed. However, the slow-up information is defined by the acceleration and the slow-down information is defined by the deceleration. Also good. In this case, the maximum travel speed reach distance D _smn can be calculated from the maximum travel speed V _mn and acceleration, and the deceleration start distance D _emn can be calculated from the maximum travel speed V _mn and deceleration.

  When the slow-up information is defined as acceleration and the slow-down information is defined as deceleration, the acceleration and deceleration may be set to larger values as the loading amount is smaller. Further, it is preferable to set acceleration and deceleration when the moving direction is lower than when the moving direction is higher to a larger value.

Next, movement control of the stacking plate 61 by the elevation control unit 68 will be described in detail with reference to FIGS.
As shown in FIG. 5, when the elevation control unit 68 receives a lowering instruction from the main control unit 9 (step A <b> 1), the elevation distance D _up measured by the upper distance measurement sensor 66 and the lower distance measurement sensor 67. The measured lower distance D _down is subtracted from the distance “Z” between the upper distance measuring sensor 66 and the lower distance measuring sensor 67 to obtain the height h of the recording paper P stacked on the stacking plate 61. Calculate (step A2). The calculation may be performed in consideration of the thickness of the stacking plate 61.

Next, the elevation control unit 68 determines the loading amount of the recording paper P based on the height h calculated in step A2 (step A3), and the loading amount determined as the moving direction (downward) in the distance speed table 69. The maximum movement speed V _mn , slow-up information, and slow-down information corresponding to the above are specified (step A4).

Next, the raising / lowering control unit 68 drives the raising / lowering motor 65 to start the lowering of the stacking plate 61, and uses the slow-up information specified in step A4 to accelerate until _reaching the maximum movement speed _Vmn (step). A5). Thus, the maximum movement speed V _mn is reached at the maximum movement speed arrival distance D _smn defined by the slow-up information from the start of the lowering of the stacking plate 61.

Next, the elevation control unit 68 lowers the stacking plate 61 at the maximum movement speed V _mn , and “Y” (the lower distance measurement sensor 67 and the lower limit) from the lower distance D _down measured by the lower distance measurement sensor 67. It waits for the value obtained by subtracting the distance to the stacking plate 61, which is the position, to reach the deceleration start distance D _emn defined in the slowdown information (step A 6).

When the value obtained by subtracting the lower distance D _down “Y” reaches the deceleration start distance D _emn , the elevating control unit 68 uses the slow-down information specified in step A4 to move the stacking plate 61 having the maximum moving speed V _mn. Decelerate and stop (step A7). As a result, the stacking plate 61 is stopped at the lower limit position where the recording paper P is supplied.

As shown in FIG. 6, when the elevation control unit 68 receives the ascending instruction from the main control unit 9 (step B <b> 1), the elevation control unit 68 uses the upper distance D _up measured by the upper distance measurement sensor 66 and the lower distance measurement sensor 67. The measured lower distance D _down is subtracted from the distance “Z” between the upper distance measuring sensor 66 and the lower distance measuring sensor 67 to obtain the height h of the recording paper P stacked on the stacking plate 61. Calculate (step A2). The calculation may be performed in consideration of the thickness of the stacking plate 61.

Next, the elevation control unit 68 determines the loading amount of the recording paper P based on the height h calculated in step A2 (step A3), and the loading amount determined as the moving direction (upward) in the distance speed table 69. The maximum movement speed V _mn , slow-up information, and slow-down information corresponding to the above are specified (step A4).

Next, the raising / lowering control unit 68 drives the raising / lowering motor 65 to start raising the stacking plate 61, and uses the slow-up information specified in Step A4 to accelerate until _reaching the maximum movement speed _Vmn (Step _S4). A5). Thus, the maximum movement speed V _mn is reached at the maximum movement speed arrival distance D _smn defined by the slow-up information from the start of the lowering of the stacking plate 61.

Next, the elevation control unit 68 raises the stacking plate 61 at the maximum moving speed V _mn, from the upper distance D _{Stay up-as} measured by the upper distance measuring sensor 66 "X" (the upper range finding sensor 66 and the feed position It waits for the value obtained by subtracting (distance) to reach the deceleration start distance D _emn defined in the slow-down information (step B2).

When the value obtained by subtracting “X” from the upper distance D _up reaches the deceleration start distance D _emn , the elevating control unit 68 uses the slowdown information specified in step A4 to move the stacking plate 61 having the maximum movement speed V _mn. Decelerate and stop (step A7). As a result, the stacking plate 61 is stopped so that the uppermost stacked recording paper P is at the paper feed position.

As described above, in the present embodiment, the stacking plate 61 on which the recording paper P is stacked, and the lifting mechanism (the wire 62, the pulley 63, the driving pulley 64, and the lifting motor 65) that move the stacking plate 61 in the vertical direction. Between the uppermost recording paper P stacked on the stacking plate 61 and disposed above the feeding position of the recording paper P stacked on the stacking plate 61. An upper distance measuring sensor 66 for measuring the upper distance D _up of the load plate 61; a lower distance measuring sensor 67 for measuring a lower distance D _down between the upper distance sensor 66 and the lower position of the stacking plate 61; A distance speed table 69 set with slowdown information defining a deceleration process when the maximum movement speed V _mn of the loading plate 61 gradually lowers the loading plate 61 from the maximum movement speed V _mn to a stop state, and a lowering Instructions are When input, the elevating mechanism starts the descent of the loading plate 61 at the maximum moving speed V _mn , and the loading plate is based on the lower distance D _down measured by the lower distance measuring sensor 67 and the slowdown information. When 61 is stopped at the lower limit position and an ascent instruction is input, the elevating mechanism starts raising the stacking plate 61 at the maximum moving speed V _mn , and the upper distance D _up measured by the upper distance measuring sensor 66 is slow. Based on the down information, an elevating control unit 68 is provided to stop the stacking plate 61 so that the uppermost recording paper P loaded becomes the paper feed position.
With this configuration, the current (or clock frequency) of the elevating motor 65 that moves the stacking plate 61 is slowed down while measuring the height position of the stacking plate 61 and the position of the recording paper P (top), Since the maximum movement speed V _mn can be set fast, the ascending / descending time can be shortened. Thereby, the waiting time at the time of supplying the recording paper, that is, the waiting time when the recording paper P is supplied to the stacking plate 61 and the waiting time after the supplying can be shortened.

Further, in the present embodiment, in the distance speed table 69, the maximum moving speed V _mn is set to a faster value as the loading amount is smaller in accordance with the loading amount of the recording paper P loaded on the loading plate 61. When the lowering instruction or the rising instruction is input, the elevating control unit 68 calculates the load amount based on the upper distance _Dup and the lower distance _Ddown, and the maximum moving speed V corresponding to the calculated load amount. _The loading plate 61 is moved by _mn .
With this configuration, the loading plate 61 can be moved at a higher maximum movement speed V _mn as the loading amount is smaller and the movement distance of the loading plate 61 is longer, and the waiting time when supplying recording paper can be shortened.

Further, in the present embodiment, in the distance speed table 69, the slowdown information is defined by the deceleration, and the deceleration is based on the loading amount of the recording paper P loaded on the loading plate 61. The smaller the value is, the larger the value is set.
With this configuration, when the load is small and the required torque of the lifting motor 65 is small, the stacking plate 61 can be stopped at a short distance. Accordingly, the moving distance can be extended at the maximum moving speed V _mn , and the waiting time when replenishing the recording paper can be shortened.

Further, in the present embodiment, in the distance speed table 69, the maximum moving speed V _mn is set to a value that is faster to descend than to rise in accordance with the moving direction of the stacking plate 61, and the elevation controller When a lowering instruction or an ascending instruction is input, 68 moves the stacking plate 61 at the maximum moving speed V _mn according to the moving direction of the stacking plate 61.
With this configuration, the movement time of the stacking plate 61 when descending can be shortened.

Furthermore, in the present embodiment, the distance speed table 69 is set with slow-up information that defines a deceleration process when the stacking plate 61 is gradually raised from the stopped state to the maximum moving speed V _mn , and the lift control unit When a lowering instruction or an ascending instruction is input, 68 starts the movement of the stacking plate 61 based on the slow-up information.
With this configuration, the stacking plate 61 can be smoothly accelerated to the maximum movement speed V _mn .

  Note that the present invention is not limited to the above-described embodiments, and it is obvious that the embodiments can be appropriately changed within the scope of the technical idea of the present invention. In addition, the number, position, shape, and the like of the constituent members are not limited to the above-described embodiment, and can be set to a suitable number, position, shape, and the like in practicing the present invention. In each figure, the same numerals are given to the same component.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Document reading part 3 Document feeding part 4 Recording part 5 Operation part 6 Paper feeder 7 Conveying part 8 Ejection tray 9 Main control part 10 Storage part 11 Image processing part 12 Cover opening / closing sensor 21 Scanner 22 Platen glass 23 Document reading slit 31 Document placement unit 32 Document transport mechanism 33 Document discharge unit 40 Image forming unit 41 Photosensitive drum 42 Charging unit 43 Exposure unit 44 Development unit 45 Transfer unit 46 Cleaning unit 47 Fixing unit 61 Stacking plate 62 Wire 63 Pulley 64 Drive pulley 65 Elevating motor 66 Upper distance sensor 67 Lower distance sensor 68 Elevation controller 69 Distance speed table 71 Paper feed roller 72 Transport roller 73 Discharge roller

Claims (6)

A paper feeding device comprising a stacking plate on which recording paper is stacked, and an elevating mechanism for moving the stacking plate in the vertical direction,
An upper distance measuring sensor which is disposed above a feeding position of the recording paper loaded on the loading plate and measures an upper distance from the uppermost recording paper loaded on the loading plate;
A lower distance measuring sensor that is disposed below a lower limit position of the loading plate and measures a lower distance between the loading plate,
A distance speed table in which the maximum movement speed of the loading plate is set together with slowdown information that defines a deceleration process when the loading plate is gradually lowered from the maximum movement speed to a stop state;
When a lowering instruction is input, the elevating mechanism starts lowering the loading plate at the maximum moving speed, and based on the lower distance measured by the lower distance measuring sensor and the slowdown information. When the stacking plate is stopped at the lower limit position and a lift instruction is input, the lifting mechanism starts to lift the stacking plate at the maximum moving speed, and the upper distance measured by the upper distance measuring sensor. And a raising / lowering control unit for stopping the stacking plate so that the stacked uppermost recording sheet is located at the sheet feeding position based on the slowdown information. In the distance speed table, the maximum moving speed is set to a faster value as the loading amount is smaller, according to the loading amount of the recording paper loaded on the loading plate,
When the lowering instruction or the ascending instruction is input, the elevating control unit calculates the load amount based on the upper distance and the lower distance, and the maximum movement speed according to the calculated load amount The sheet feeding device according to claim 1, wherein the stacking plate is moved.   In the distance / velocity table, the slowdown information is defined by deceleration, and the deceleration is set to a larger value as the loading amount is smaller according to the loading amount of the recording paper loaded on the loading plate. The sheet feeding device according to claim 1, wherein the sheet feeding device is provided. In the distance speed table, the maximum moving speed is set to a value that is faster to descend than to rise according to the moving direction of the stacking plate,
4. The lift control unit according to claim 1, wherein when the lowering instruction or the raising instruction is input, the lifting control unit moves the stacking plate at the maximum moving speed according to a moving direction of the stacking plate. The sheet feeder according to any one of the above. In the distance speed table, slow-up information defining a deceleration process when gradually raising the stacking plate from the stopped state to the maximum moving speed is set,
The said raising / lowering control part starts the movement of the said stacking board based on the said slow-up information, if the said lowering instruction | indication or the said raising instruction | indication is input. Paper feeder. A paper feeding device according to any one of claims 1 to 5,
An image forming apparatus comprising: an image forming unit configured to record a formed image on the recording paper fed from the paper feeding device.

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