JP7099813B2 - Paper feed device - Google Patents

Description

The present invention relates to a paper feeding device that supplies a sheet to an image forming device or the like.

Conventionally, a paper feeding device for feeding a sheet to an image forming unit of an image forming device such as a copying machine or a printer has been known.

The paper feed device includes a storage that can store thousands of large-capacity sheets, a loading tray that is provided in the storage to load sheets, an elevating mechanism that raises and lowers this loading tray, and an elevating mechanism. It is equipped with a drive motor that drives the sheet, a feeding roller that contacts the uppermost surface of the sheet on the loading tray and feeds the sheet, and a separation mechanism that separates the fed sheet into one sheet and feeds it. Then, when the seat is set on the loading tray, the drive motor is driven to raise the elevating tray. The ascending loading tray stops when the top surface of the seat touches the feeding roller. After that, the delivery roller is driven to feed the sheet, and the sheet is separated into one sheet by the separation mechanism and supplied to the image forming unit.

In such a paper feed device, small size sheets such as A6, B5, A4 and letters, large size sheets such as B4, A3 and legal, and sheets of various sizes such as long sheets (sheets other than standard size) are available. It can be handled (for example, Patent Document 1 and Patent Document 2). In addition, various sheets such as plain paper and film sheets can be handled.

Japanese Patent Application Laid-Open No. 2003-63719 JP-A-2002-338069

By the way, in the image forming apparatus, the size frequently used is A4 (small size sheet), and the frequency of using large size sheets (B4, A3) and long sheets (sheets other than the standard size) of A4 size or larger is Less than small size sheets. In addition, special paper such as film sheets are used less frequently than plain paper.

However, large-sized sheets and film sheets are heavier than small-sized sheets, and the device configuration and parts are designed based on the heaviest sheets that can be handled, so the maximum size of sheets that can be handled. The heavier the material of the sheet and the heavier the material of the sheet, the heavier the maximum weight of the sheet on the loading tray. When the maximum weight of the seat on the loading tray becomes heavier, the elevating mechanism needs to have a stronger configuration, and the elevating motor also needs a motor with a large torque. Therefore, the elevating motor becomes large and the power consumption increases. In addition, there is a problem that the weight of the elevating mechanism becomes heavy and becomes complicated.

The present invention has been made in view of the above problems, and provides a paper feeding device capable of handling various sheets without complicating the device for handling various sheets and increasing the weight of the device. The purpose is.

In view of the above object, the present invention is a paper feeding device including a loading tray for loading sheets, a paper feeding means for feeding sheets on the loading tray, and an elevating means for moving the loading tray in the vertical direction. The elevating means lowers the loading tray when the sheet is loaded beyond the predetermined position provided between the upper and lower sides where the loading tray moves, and loads when the loading tray reaches the set position set according to the type of sheet. Stop descending the tray.

When the loading tray reaches the set position set according to the type of sheet, the lowering of the loading tray is stopped, so that the maximum loading capacity of the sheet on the loading tray can be easily changed, and the structure becomes complicated. It is possible to handle various sheets with the paper feed device while suppressing the increase in weight and cost.

It is a figure which shows the whole structure of an image formation system. It is a schematic diagram which shows the structure of a paper feed device. It is a plan schematic diagram which shows the structure of a paper feed device. It is a top view which shows the state which pulled out the storage from the paper feed device main body. It is an operation flowchart which shows the series flow of the operation of exchanging a sheet in a storage. It is a flowchart which shows the process of replenishing, taking out, and setting a size of a sheet in a replacement operation. It is a phase diagram which shows the operation state which replaces an A4 size sheet with an A3 size sheet. It is a phase diagram which shows the operation state which replaces an A4 size sheet with an A3 size sheet. It is a phase diagram which shows the operation state which replaces an A3 size sheet with an A4 size sheet. It is a phase diagram which shows the operation state which replaces an A3 size sheet with an A4 size sheet.

FIG. 1 is a diagram showing an overall configuration of an image forming system. First, the overall configuration of the image forming system will be described with reference to FIG. The image forming system includes an image forming device 2, a document reading device 3, a document feeding device 4, a paper feeding device 5, and a sheet stacking device 6. The image forming apparatus 2 includes two paper feed cassettes 7a and 7b capable of storing about 100 sheets, and the paper feed cassettes 7a and 7b are based on the image data read from the original image by the original reading device 3. An image is formed on a sheet supplied from any one of 7b and the paper feeding device 5. Then, the image-formed sheets are accumulated and stored in the sheet accumulating device 6. A document sheet can also be fed to the document reading device 3 by the document feeding device 4. Here, the sheets handled in the image forming system include small size paper such as A6, B5, A4 and large size plain paper such as B4, A3, long sheets other than the standard size, and film sheets including OHP sheets. , Tracing paper, coated paper and other special sheets shall be included.

As shown in FIG. 1, the image forming apparatus 2 includes a floodlight (laser head or the like) 8, a photosensitive drum 9, a developing device 10, a transfer charger 11, and a fixing roller 12. An electrostatic latent image (still image) is formed on the surface of the photosensitive drum 9 by the floodlight 8, toner is adhered to the electrostatic latent image by the developer 10, and the toner adhered on the photosensitive drum 9 is a paper feed cassette. It is transferred by the transfer charger 11 to the sheets supplied from 7a, 7b or the paper feed device 5. The sheet to which the toner is transferred is sent to the fixing roller 12 arranged on the downstream side, the toner on the sheet is heat-fixed, and then the sheet is discharged to the sheet accumulating device 6 by the paper ejection roller pair 13.

Each of the paper cassettes 7a and 7b is separated into a delivery roller 14 that contacts the uppermost surface of the stored sheet and feeds the sheet, and a paper feed roller that separates the sent sheets into one sheet and feeds the sheet. A separation mechanism 15 including a roller is provided. The sheets sent out from the paper cassettes 7a and 7b by the delivery rollers 14 and separated one by one by the separation mechanism 15 are conveyed by a plurality of transport roller pairs and sent to the transfer charger 11 along the transport path. Further, the sheets fed from the paper feed device 5 are carried into the transfer path 17 by the carry-in roller pair 26, and similarly, are sent to the transfer charger 11 along the transfer path 17 by the transfer roller pair 16.

The image forming apparatus 2 is provided with a control panel 25 (see FIG. 2). Using the control panel 25, it is possible to set image formation conditions such as sheet type, color printing / monochrome printing, number of copies, single-sided printing / double-sided printing, and enlargement / reduction printing.

A first platen 19 and a second platen 20 made of transparent glass are arranged side by side in the horizontal direction on the upper part of the document reading device 3. The first platen 19 is used for reading a document set by hand, and is formed in a size capable of mounting a document having the maximum size that can be supported. Further, the second platen 20 is used for reading a document fed from the document feeding device 4 and moving at a predetermined speed.

Inside the document reading device 3, a photoelectric conversion means having a first reading carriage 21 and a second reading carriage 22, a condensing lens 23, and a photoelectric conversion element 24 is provided. The first read carriage 21 and the second read carriage 22 are driven by a carriage motor (not shown) and reciprocate below the first platen 19 in the sub-scanning direction. The first reading carriage 21 is provided with a lamp that irradiates light toward the document and a mirror that reflects the light reflected from the document, and the second reading carriage 22 is provided with the first reading. Two mirrors are provided to guide the light from the mirror of the carriage 21 to the condenser lens 23 and the photoelectric conversion element 24. When reading a document on the first platen 19, the first reading carriage 21 and the second reading carriage 22 are moved and placed on the first platen 19 from the first reading carriage 21. By irradiating the image of the document with light and guiding the reflected light from the document to the photoelectric conversion element 24 via the first reading carriage 21 and the second reading carriage 22, the light is converted into an electric signal from the document. Generate image data.

The document transporting device 4 includes a paper feed tray 28, a sheet transport mechanism 29, and a paper ejection tray 30, and transports the documents placed on the paper feed tray 28 one by one by the sheet transport mechanism 29. It passes over the second platen 20 and is discharged to the paper ejection tray 30. When reading a document fed from the document transport device 4 and passing over the second platen 20, the first reading carriage 21 and the second reading carriage 22 are stopped in advance below the second platen 20. Then, the document passing over the second platen 20 is read and image data is generated.

FIG. 2 is a schematic view showing the configuration of the paper feed device 5, and FIG. 3 is a plan schematic view showing the configuration of the paper feed device 5. Further, FIG. 4 is a plan view showing a state in which the storage is pulled out from the main body (housing) of the paper feed device. The configuration of the paper feed device 5 will be described with reference to FIGS. 1 to 4. The paper feed device 5 combines the housing 31, the storage 33 that is supported in the housing 31 so as to be able to be pulled out in the direction orthogonal to the paper feeding direction, and the sheets in the storage 33, one by one. A separate feeding mechanism 43 that separates and supplies the image to the image forming apparatus 2 and a control unit 35 that controls the feeding device 5 are provided, and a loading tray 36 that can be raised and lowered in the vertical direction is provided in the storage 33. It is provided. The loading tray 36 is a plate-shaped plate, and each of a small size sheet of a predetermined size or less and a large size sheet larger than a predetermined size can be loaded on the loading tray 36. A top surface detection sensor 39 for detecting the uppermost surface of the sheet loaded on the loading tray 36 is provided on the upper part of the storage 33, and the loading tray 36 is moved according to the amount of the sheet by the elevating mechanism. It has become.

The elevating mechanism 40 includes a plurality of wires fixed to the support portion of the loading tray 36 (only one wire is shown for simplification in FIG. 2), and a take-up pulley for winding the corresponding wire. It is composed of an intermediate pulley around which a wire extending between the take-up pulley and the corresponding support portion is wound, and an elevating motor M1 for rotationally driving the take-up pulley 50.

The storage 33 has a substantially box-shaped shape with an opening at the top, and as shown in FIG. 4, the loading tray in the storage 33 passes through the opening when it is pulled out from the housing 31. Sheets can be loaded on the 36. In the loading tray accommodating space for accommodating the loading tray 36 inside the storage 33, the side end restricting members 41a and 41b located sandwiching the sheet on the loading tray 36 in the width direction and the sheet on the loading tray 36 A rear end restricting member 42 located on the rear end side in the paper feeding direction is provided. That is, both side ends of the sheet on the loading tray 36 in the width direction are regulated by the side end regulating member, and the rear ends of the sheet on the loading tray 36 in the paper feeding direction are regulated by the rear end regulating member 42. .. The side end restricting members 41a and 41b are interlocked and slidably slidable in the width direction of the seat, and are erected at the bottom of the storage 33. The rear end restricting member 42 is erected at the bottom of the storage 33 so as to be slidable in the paper feeding direction. With such a configuration, the side end restricting members 41a and 41b and the rear end restricting member 42 are moved in the storage 33 according to the sheet size to regulate the side end position of the sheet and the rear end position in the paper feeding direction. You can do it.

The separate paper feed mechanism 43 includes a feeding roller 45 that comes into contact with the uppermost surface of the sheet loaded on the loading tray 36 and feeds the sheet, and a paper feed roller 46 that feeds the fed sheet to the image forming apparatus 2. It is composed of a separation roller 47 that presses against the paper feed roller 46 to prevent the supply of the second and subsequent sheets.

The paper feed roller 46 is driven by the paper feed motor M2 via a plurality of gears and timing belts (not shown), and is rotated by the drive of the paper feed motor M2 to supply the sheet. The feeding roller 45 is rotatably supported by a bracket rotatably supported around the shaft of the paper feeding roller 46, and the rotation of the shaft of the paper feeding roller 46 by the paper feeding motor M2 causes a plurality of gears. It is transmitted to the feeding roller 45 via the feed roller 45 and is rotationally driven. Further, the feeding roller 45 can be moved around the shaft of the paper feed roller 46 between the operating position in contact with the upper surface of the sheet and the standby position away from the upper surface of the sheet. In the present embodiment, the bracket is rotated by the rotation of the shaft of the paper feed roller, and the feeding roller 45 is moved between the operating position and the standby position.

A torque limiter is attached to the rotation shaft of the separation roller 47. As a result, when two or more sheets are overlapped and niped at the pressure contact portion between the paper feed roller 46 and the separation roller 47, the separation roller 47 stops and the supply of the second and subsequent sheets from the top is blocked. It has become. That is, when a plurality of sheets overlap and enter the nip portion of the paper feed roller 46 and the separation roller 47, the driving force of the paper feed roller 46 is transmitted to the highest sheet, while the rotation of the separation roller 47 is stopped. , A slip occurs between the top sheet and the second and subsequent sheets from the top, and the top sheet and the second and subsequent sheets from the top are separated. Of course, instead of the separation roller 47, another friction member such as a separation pad may be used.

As shown in FIG. 2, the control unit 35 that controls the operation of the paper feeding device 5 is provided in the image forming device 2. The control unit 35 sets the paper feed device 5 based on the image forming conditions such as the sheet type, color printing / monochrome printing, number of copies, single-sided printing / double-sided printing, and enlargement / reduction printing set in the control panel 25 described above. Control.

Here, in the control unit 35 of the present embodiment, in order to make the maximum load capacity of the sheets loaded on the loading tray 36 different according to the type of the sheet, the loading tray 36 is lowered based on the type of the sheet. The lower limit position to be restricted is set. That is, when the weight per sheet is heavy due to the material and size of the sheet, the lower limit position is set high to limit the maximum loadable area of the sheet on the loading tray 36, and the sheet on the loading tray 36. The space for loading is reduced to reduce the maximum load capacity.

The feeding device 5 includes a top surface detection sensor 39 that detects that the uppermost surface of the sheet has moved to the feeding position where the sheet is fed out, and a take-out sensor 58a that detects that the upper surface of the sheet has moved to the replenishing position that replenishes the sheet. The first and second take-out sensors 58b for detecting that the upper surface of the sheet has moved to the take-out position for taking out the sheet and the first and second loading trays 36 are arranged at different positions in the ascending / descending direction of the loading tray 36 to limit the lowering of the loading tray 36. Lower limit sensors 57a and 57b and an encoder 51 that generates a pulse signal as the loading tray 36 moves up and down are provided. Further, the bottom of the storage 33 is provided with first and second size sensors 59a and 59b for detecting the position of the rear end regulation plate 42. In the present embodiment, there are two types of sheets of the size to be handled, A4 and A3, and the first and second size sensors 59a and 59b are the position of the rear end control plate 42 that regulates the rear end of the A4 size sheet and A3. It is arranged at each position of the rear end control plate 42 that regulates the rear end of the size sheet.

The control unit 35 receives information from the control panel 25, the above-mentioned various sensors, detection signals and pulse signals of the encoder CN, controls the elevating motor M1, the paper feed motor M2, and the solenoid 49, and elevates and elevates the loading tray 36. Operation and sheet feeding operation of the separate feeding mechanism 34 are executed.

In the elevating operation of the loading tray 36, the elevating motor M1 is controlled so as to raise the loading tray 36 and move the uppermost surface of the sheet to the feeding position for feeding by the feeding roller 45. Further, when the sheet is taken out and the sheet is replenished, the loading tray 36 is raised or lowered, and the elevating motor M1 is controlled so as to be the taking-out position and the replenishing position of the uppermost surface of the sheet. In this embodiment, the take-out position and the replenishment position are provided above the central position in the height direction of the storage 33.

In the paper feeding operation, in response to the paper feeding signal from the control panel 25, the feeding roller 45 is moved to an operating position in contact with the uppermost surface of the sheet, and the feeding roller 45 and the paper feeding roller 46 are rotated to feed the sheet. The paper feed motor M2 is controlled in such a manner.

Further, as described above, the control unit 35 sets the lower limit position when the loading tray 36 moves up and down depending on the type of the sheet loaded on the loading tray 36. In the present embodiment, the lower limit position of the loading tray 36 is set based on the sheet size specified by the detection signals of the first and second size sensors 59a and 59b. When the sheet size is A4 size, it is set at the first lower limit position near the bottom surface of the storage 33, and when the sheet size is A3 size, it is set at the second lower limit position above the first lower limit position.

The first lower limit sensor 57a is arranged at the first lower limit position, and the second lower limit sensor 57b is arranged at the second lower limit position. The control unit 35 selects the first lower limit sensor 57a when the first lower limit position is set according to the seat size, and controls to stop the reversal of the elevating motor M1 when the first lower limit sensor 57a detects the loading tray 36. do. Further, when the second lower limit position is set according to the seat size, the second lower limit sensor 57a is selected, and when the second lower limit sensor 57a detects the loading tray 36, the elevating motor M1 is controlled to stop reversing. Hereinafter, the lower limit sensor selected by the first and second lower limit sensors 57a and 57b will be referred to as a set lower limit sensor.

FIG. 5 is an operation flowchart showing a series of flows of the operation of replacing the sheet in the storage 33, and FIG. 6 is a flowchart showing a process of replenishing, taking out, and specifying the sheet size in the replacement operation. 7 and 8 are state diagrams showing an operating state in which an A4 size sheet is replaced with an A3 size sheet, and FIGS. 9 and 10 are state diagrams showing an operating state in which an A3 size sheet is replaced with an A4 size sheet. It is a figure.

The operation of replacement will be described with reference to FIGS. 5 to 10. When the unlock button 44 shown in FIG. 2 is pressed while the sheet feeding operation is stopped as shown in FIGS. 7 (a) or 9 (a), the elevating motor M1 is reversely driven to drive the loading tray 36. Goes down (ST01 to ST02). At the same time, it is detected whether or not the replenishment sensor 58a is in the ON state (ST03). As shown in FIG. 2, the replenishment sensor 58a is arranged at the upper part of the side surface of the storage 33, and outputs an ON signal when the loading tray 36 and the sheet to be loaded are detected (ON state) and does not detect the loading tray 36. In the (OFF state), an OFF signal is output.

If the replenishment sensor 58a is in the OFF state when the release button 44 of the storage 33 is pressed, it is determined that the loading tray 36 is above the detection position of the replenishment sensor 58a. Then, by lowering the loading tray 36, the device waits until either the lower limit setting sensor or the replenishment sensor 58a selected according to the size of the sheet is turned on. On the other hand, when the replenishment sensor 58a is in the ON state when the release button 44 is pressed, the loading tray 36 is below the detection position or the detection position of the replenishment sensor 58a, and the top surface of the loaded sheet is the detection position. Judge that it is above.

If the lower limit setting sensor is turned on before the replenishment sensor 58a is turned on, the process proceeds to refilling, taking out, and sizing (ST04). On the other hand, if the replenishment sensor 58a is turned off before the set lower limit sensor is turned on, the elevating motor M1 is stopped and the lowering of the loading tray 36 is stopped (ST05 to ST06). At this time, as shown in FIGS. 7 (b) and 9 (b), the uppermost surface of the sheet on the loading tray 36 reaches the replenishment position h1 and stops. If there is no sheet on the loading tray 36, the upper surface (sheet loading surface) of the loading tray 36 is positioned at the replenishment position h1.

When the loading tray 36 is stopped, the solenoid 49 is activated to unlock the storage 33 (ST07). As a result, as shown in FIG. 4, the storage 33 is pulled out from the main body (housing) of the paper feeding device 5. Then, the replenishment, removal, and size setting processing for replenishing, taking out, and specifying the sheet size of the sheet is executed (ST08).

As shown in FIG. 4, when the storage 33 is pulled out, the user replenishes the same seat without changing the seat size, or newly fills a different type of seat from the previously loaded type of seat. Do either loading.

Explaining the replenishment, removal, and size setting process (ST08) based on FIG. 6, in the present embodiment, as shown in FIGS. 7 (b) and 9 (b), the top surface of the sheet on the loading tray 36 is the replenishment position. When the replenishment sensor 58a is turned on from the state of reaching h1, it is determined that a sheet of the same size is replenished or a sheet of a different size is newly placed, and the replenishment operation is executed (ST11 to ST14). When the take-out sensor 58b is turned off from the state where the uppermost surface of the sheet on the load tray 36 reaches the replenishment position h1, it is determined that the sheet of the load tray 36 has been removed, and the take-out operation is executed (ST15 to ST17). Further, when the replenishment sensor 58a is in the OFF state and the take-out sensor 58b is in the ON state, a size setting operation (ST18 to ST21) for monitoring whether or not the sheet type has been changed and specifying the size is executed.

The take-out sensor 58b is arranged slightly below the replenishment sensor 58a. Specifically, the distance between the replenishment sensor 58a and the side surface 36a of the loading tray 36 in the height direction (thickness of the loading tray 36) is smaller, and the replenishment sensor 58a does not detect the uppermost surface of the sheet (the state where the replenishment sensor 58a does not detect the uppermost surface of the sheet). It is arranged at a position where the seat is detected (ON state) in the OFF state). Therefore, when the uppermost surface of the sheet or the upper surface of the loading tray 36 is at the replenishment position h1, the take-out sensor 58b is in a state of detecting the sheet or the loading tray 36 (ON state).

Here, when the user replaces the sheet in the storage 33 with a sheet of a different size, the sheet accumulated on the loading tray 36 is taken out, and the rear end regulating plate 42 is moved to a position corresponding to the sheet to be replaced. The sheet to be replaced after that is placed on the loading tray 36. In the subsequent description of the replenishment, retrieval, and size setting processing (ST08), for convenience, each processing will be described in the order of the retrieval process, the size setting process, and the replenishment process according to the above-mentioned operation when the user replaces the sheet. Here, as an example, a case of changing an A4 size sheet to an A3 size sheet and a case of changing an A3 size sheet to an A4 size sheet will be described.

The take-out process determines that the sheet of the loading tray 36 has been removed when the take-out sensor 58b is turned off, and rotates the elevating motor M1 in the normal direction (ST15 to ST16). As a result, the loading tray 36 is raised as shown in FIGS. 7 (c) and 9 (c). When the loading tray 36 rises and the take-out sensor 58b is turned on, the elevating motor M1 is stopped and the loading tray 36 is stopped (ST17, ST22).

At this time, if the sheet is divided into a plurality of pieces and taken out as shown in FIG. 7C, in other words, if the sheet remains on the loading tray 36, the take-out sensor 58b detects (ON state) on the uppermost surface of the sheet. After that, when the remaining sheet is removed as shown in FIG. 8 (e), the take-out sensor 58b is turned off again, and the take-out process (ST15 to ST17) is executed again. That is, in processing, regardless of whether or not the sheet on the loading tray 36 is loaded, the replenishment process, the extraction process, and the size setting are performed according to the detection state (ON-OFF state) of the replenishment sensor 58a and the extraction sensor 58b. One of the processes is executed. Therefore, if the take-out sensor 58b is turned off with the sheet remaining on the loading tray 36, the take-out process (ST15 to ST17) is repeatedly executed. If the sheet does not remain on the loading tray 36, the upper surface of the loading tray 36 is positioned at the take-out position h2 as shown in FIGS. 8 (f) and 9 (d). note that,
When the sheet does not remain on the loading tray 36, the upper surface of the loading tray 36 is positioned at the take-out position h2 as shown in FIGS. 8 (f) and 9 (d).

The size setting process is executed when the replenishment sensor 58a is in the OFF state and the take-out sensor 58b is in the ON state. In the size setting process, it is confirmed whether or not the first size sensor is in the ON state (ST18). If the first size sensor is in the ON state, the lower limit position corresponding to the lower limit sensor A4 size is set assuming that the rear end regulation plate 42 is in the first position corresponding to the A4 size sheet, and the first setting lower limit sensor is set. The lower limit sensor 57a of is selected (ST19). On the other hand, if the first size sensor is in the OFF state, it is confirmed whether or not the second size sensor is in the ON state (ST20). Then, if the second size sensor is in the ON state, the lower limit position corresponding to the A3 size is set assuming that the rear end regulating plate 42 is in the second position corresponding to the A3 size sheet. Then, the first lower limit sensor 57a is selected as the set lower limit sensor (ST21).

That is, in order to replace the sheet in the storage 33 from the A4 size sheet to the A3 size sheet, the A4 size sheet is taken out from the storage 33, and the rear end regulation plate 42 is moved from the first position to the second position. (See FIGS. 8 (e) and 8 (f)) and the first lower limit position H2 corresponding to the A3 size is set. Further, in order to replace the sheet in the storage 33 from the A3 size sheet to the A4 size sheet, the A3 size sheet is taken out from the storage 33, and the rear end regulation plate 42 is moved from the second position to the first position. (See FIGS. 9 (c) and 9 (d)), a second lower limit position H2 corresponding to the A4 size is set. In this way, the size setting process also functions as a setting means for setting the lower limit position according to the sheet size.

Next, the replenishment operation will be described. When the replenishment sensor 58a is switched from the OFF state to the ON state, it is determined that the sheet is placed on the loading tray 36 or the sheet is replenished, and the elevating motor M2 is reversed (ST11 to ST12). .. As a result, the loading tray 36 is lowered as shown in FIGS. 8 (f), 8 (g), 10 (e), and 10 (f). Then, when the set lower limit sensor selected from the first and second lower limit sensors 57a and 57b is turned on, the elevating motor M1 is stopped (ST13, ST22).

On the other hand, if the replenishment sensor 58a is turned off before the selected lower limit sensor is turned on, the elevating motor M1 is stopped (ST14, ST22). At this time, as shown in FIG. 8 (g), the uppermost surface of the sheet is positioned at the replenishment position h1. Then, when the replenishment sensor 58a is turned on again, it is determined that the replenishment sensor 58a has been further replenished, and the replenishment process (ST11 to ST14) is repeatedly executed. That is, in the case of an A3 size sheet, the sheet can be loaded until the loading tray 36 descends to the second lower limit position H2 detected by the second lower limit sensor 57b as shown in FIG. 8 (h). .. Further, in the case of an A4 size sheet, as shown in FIG. 10 (g), the sheet can be loaded until the loading tray 36 descends to the first lower limit position H1 detected by the first lower limit sensor 57a. ..

When the replenishment, removal, and size setting processing (ST08) are completed, it is confirmed whether or not the mounting sensor 60 shown in FIG. 3 is ON. The mounting sensor 60 detects whether or not the storage 33 is mounted on the main body (housing 31) of the paper feeding device 5. If the mounting sensor 60 is ON, it is determined that the operation of pulling out the storage 33 such as replenishment and removal of the sheet is completed, and the series of processes of pulling out the storage 33 is completed. If the mounting sensor 60 remains in the OFF state, the replenishment process, the extraction process, and the size setting process are executed depending on the ON / OFF state of the replenishment sensor 58a and the extraction sensor 58b.

[Other embodiments]
In the take-out process in the above-described embodiment, the loading tray 36 is raised each time the sheet is taken out, and the uppermost surface of the sheet is moved to the take-out position h2, but all the sheets are removed with the loading tray 36 stopped. The upper surface of the loading tray 36 may be moved to the take-out position based on the detection that there is no sheet on the loading tray 36. In this case, the presence / absence of a sheet on the loading tray 36 is determined by providing a detection sensor on the upper surface of the loading tray 36 so as to directly detect the presence / absence of a sheet on the loading tray 36.

In the above-described embodiment, two types of sheets, A4 and A3, are shown as an example of the types of sheets, but it is needless to say that they are also applied to two or more types of sheets. Further, the type of the sheet may be set as the material of the sheet, and a different lower limit position may be set for each material of the sheet. Furthermore, it is also possible to set the lower limit position by combining the size and the material.

In the present embodiment, the seat size is specified by the position of the rear end control plate 42, but the control panel 25 is provided with a setting button for setting the seat size, and the seat size set by the user is received by the control unit 35. , The second lower limit positions H1 and H2 may be selected to set the lowermost lower limit position.

In the present embodiment, the first and second lower limit sensors 37a and 37b are used to detect that the loading tray 36 reaches the first and second lower limit positions, but the number of pulses of the encoder CN is determined. The position of the loading tray 36 may be monitored by measurement and calculation, and it may be specified that the loading tray 36 has reached the first and second lower limit positions based on the number of pulses of the encoder CN.

[Effect of embodiment]
When the sheet is taken out, the loading tray 36 is raised and the uppermost surface of the loaded sheet is moved to the take-out position h2 set at the upper part of the storage 33, so that the user can move to the deep position of the storage 33. There is no need to insert a hand to remove the sheet, which makes it easier to remove the sheet. Further, when replenishing the sheets, the loading tray 36 is lowered and the uppermost surface of the loaded sheets is moved to a predetermined position of the replenishment position h1 set in the upper part of the storage 33. Even if there is no sheet in the tray, the user does not need to insert his / her hand into the deep position of the storage 33 to replenish the sheet, which facilitates the replenishment of the sheet.

When the size of the sheet loaded on the loading tray 36 is A4, the first lower limit position is set, and when the size of the sheet is A3, the second position above the first lower limit position is set. Since it is set to, the loadable capacity of the A3 size sheet can be surely smaller than the loadable capacity of the A4 size sheet. This makes it possible to handle A3 size sheets with the drive and structure applied to A4 size sheets.

Before loading the sheets, the loading tray 36 is moved to the replenishment position h1 and the loading tray 36 is configured to be lowered according to the amount of the sheets to be loaded so that the loading tray 36 does not lower below the set lower limit position. did. This ensures that more sheets than the load capacity set based on the type of sheet are loaded.

2 Image forming device 3 Document reading device 4 Document feeding device 5 Paper feeding device 6 Sheet stacking device 25 Control panel 31 Housing 31
33 Storage 35 Control unit 36 Loading tray 39 Top surface detection sensor 40 Lifting mechanism 42 Rear end control member 44 Release button 58a Replenishment sensor 58b Extraction sensor 57a First lower limit sensor 57b First and second lower limit sensors 59a First size Sensor 59b Second size sensor 60 Mounted sensor 60
M1 lift motor

Claims (6)

A loading tray for loading sheets and
A paper feeding means for feeding sheets on the loading tray, and
An elevating means for moving the loading tray in the vertical direction and
In a paper feed device equipped with
When replacing a sheet on the loading tray with a different type of sheet, a specific means for specifying the type of the sheet to be placed is provided before the sheet is placed on the loading tray.
The elevating means is
When replacing a sheet on the loading tray with a different type of sheet, the sheet is placed on the loading tray when the loading tray is below the stop position corresponding to the type of sheet specified by the specific means. Move the loading tray above the stop position before
When a sheet is loaded beyond a predetermined position provided between the upper and lower parts where the loading tray moves, the loading tray is lowered, and the loading tray is placed at the stop position according to the type of the sheet specified by the specific means. A paper feed device that stops the lowering of the loading tray when the load reaches. The paper feeding device according to claim 1, wherein the type of the sheet includes at least the size of the sheet or the material of the sheet. The paper feed according to claim 1, wherein when the weight of one sheet is small, the stop position is set as the first position, and when the weight is large, the stop position is set as the second set position above the first position. Device. A housing, a storage that can be pulled out from the housing and stores a sheet, a loading tray that is provided in the storage and loads a sheet, and a sheet on the loading tray are fed. In a paper feeding device including a paper feeding means and an elevating means for moving the loading tray in the vertical direction.
A detection means for detecting a sheet at a predetermined position between the upper and lower parts where the loading tray moves, and
A rear end regulating member that can be moved to a position that regulates the rear end of the sheet loaded on the loading tray, and
When replacing a sheet on the loading tray with a sheet of a different size, a size specifying means for preliminarily specifying the size of the sheet to be placed according to the position of the rear end restricting member before placing the sheet on the loading tray. When,
A setting means for setting a lower limit position in the moving range of the loading tray based on the sheet size specified by the size specifying means is provided.
The elevating means is
When replacing a sheet on the loading tray with a sheet of a different size, when the loading tray is below the lower limit position set by the setting means, the lower limit is set before the sheet is placed on the loading tray. Move the loading tray above the position and
In the state where the storage is pulled out, the loading tray is lowered based on the detection of the sheet by the detection means, and the loading tray reaches the lower limit position set by the setting means. A paper feed device that stops the loading tray. The setting means sets the lower limit position to the first position when the size of the sheet specified by the size specifying means is equal to or less than the predetermined size, and the lower limit when the size of the sheet is larger than the predetermined size. The paper feed device according to claim 4, wherein the position is set to a second position above the first position. The paper feeding device according to claim 5, wherein the predetermined position is a position above the second position.

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