JP3522379B2 - Paper feeder in image forming apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device for feeding a sheet to be image-formed to an image forming apparatus such as a copying machine, a printing machine, a facsimile and a printer.

[0002]

2. Description of the Related Art In an image forming apparatus such as a stencil printing machine,
Continuously using the same size printing paper, and
A large number of copies may be printed, and a large-capacity paper feeder may be used. However, there are times when it is desired to print on different sizes of paper even when the large-capacity paper feeding device is installed, and a large-capacity paper feeding device with an interrupt cassette is desirable.
An example of a paper feeding device having an interruption cassette is Jikken Sho6.
There are the ones described in Japanese Patent Publication No. 1-36517 and Japanese Patent Publication No. 4-33691, but these require a dedicated paper feed mechanism to be provided in the interrupt cassette as well, resulting in high cost and each paper feed unit. There is a demerit that the paper transport path from the to is complicated and a transport jam or the like is likely to occur.

In order to eliminate these various disadvantages, for example, JP-A-6-271104 and 6-27111.
8, the technique described in the same 6-271120 gazette is proposed. A paper feeding device using these techniques is a high-capacity paper feeding device of interrupt cassette (paper feeding cassette) type capable of selecting a large number of sheets feeding and a cassette feeding, and the same pickup roller ( Paper feeding roller) is used to feed paper. More specifically, in these paper feeding devices, an interrupt cassette can be installed on the upper surface of the paper feeding unit, and when the paper is fed from the cassette, the paper feeding unit that performs the elevating operation required for paper feeding and the paper feeding unit are provided. A cassette base as a first paper feed table that has a cutout part that can pass through a paper feed roller when moving up and down together with a paper unit, and a second paper feed that can be raised and lowered independently in the paper feed unit A multi-sheet feeding table (paper feeding tray ..., sometimes abbreviated as “LCT” hereinafter) as a table, and the sheet feeding unit and the LCT are vertically moved by different lifting drive mechanisms inside the same frame. When the LCT is used, the upper surface of the sheet feeding unit escapes the single sheet feeding roller portion so that the upper surface of the sheet feeding unit is located above the sheet feeding roller portion.
It is configured so that paper can be fed from T. In such an interruption cassette type large-capacity sheet feeding device, it is true that a single sheet feeding mechanism and a sheet feeding path are selectively fed from the multi-sheet feeding table and the interruption cassette. Paper can be used, and the above disadvantages can be almost eliminated.

Further, the above-mentioned Japanese Patent Laid-Open No. 6-271104,
In the techniques disclosed in JP-A-6-271118 and JP-A-6-271120, since a single paper feed unit is used to feed paper in an interrupt cassette, when the cassette is mounted and when a multi-sheet feeder is used. Therefore, it is necessary to prevent the devices from being damaged because the modes are easily switched and the mutual operations interfere with each other. Also, since mechanical operation is required to switch between the use of cassettes and the use of multiple-sheet feeders,
At the time of switching, it is also necessary to devise a method that reduces the waiting time until the start of feeding. As an example corresponding to these, the technique described in Japanese Patent Laid-Open No. 6-271124 and 6-271125 is proposed. The paper feeding device described in Japanese Patent Application Laid-Open No. 6-271124 is capable of mounting a cassette on the upper surface thereof, and is capable of moving up and down, and a multi-sheet feeding table capable of moving up and down independently in the paper feeding unit. A drive device for moving the multi-sheet feed tray and the paper feed unit up and down, cassette presence / absence detection means, mode determination means for inputting a signal from the cassette presence / absence detection means and a power switch signal to set a mode, Cassette feed mode /
The switching of the multi-sheet feeding mode and the operation of each mode are performed. Also, in the cassette mode, the paper feeding unit is raised so that paper can be fed from the cassette. In the multi-sheet feeding mode, the multi-sheet feeding tray is raised to feed paper from the multi-sheet feeding tray. It is supposed to be in a state. Further, the sheet feeding device described in Japanese Patent Laid-Open No. 6-271125 is further provided with a cover opening / closing detecting means in the sheet feeding device described in Japanese Patent Laid-Open No. 6-271124, and when the cover is closed, it is based on a signal of cassette presence / absence detection. Therefore, the paper feeding unit or the multi-sheet feeding table is moved up and down, and when the cover is closed without the cassette, the multi-sheet feeding table is raised to the paper feeding position.

[0005]

However, for example, the above-mentioned Japanese Unexamined Patent Publication Nos. 6-271104 and 6-271118 are disclosed.
And the former technique described in Japanese Patent Laid-Open No. 6-271120 has the following problems.

[0006] In order to feed the cassette, a large sheet feeding unit having an LCT inside is required, and a drive mechanism for raising and lowering the sheet feeding unit in response to the cassette sheet feeding operation is also required. With this configuration, the entire device becomes complicated and large.

When a multi-sheet feeding table is used, since the cassette table provided above the sheet feeding unit is elevated above the sheet feeding roller, the cassette table is stored above the sheet feeding roller. Need a large space. However, when the image forming apparatus is a general office stencil printing machine in which a plate making mechanism and a printing mechanism are integrated as shown in, for example, JP-A-6-171819, the stencil printer main body is used. Since the plate making section, the plate discharge section, etc. are usually arranged in the corresponding section, if the large space as described above is provided above the sheet feeding roller, the plate making section, the plate discharge section, etc. must be moved upward. As a result of this relocation, the document reading unit disposed above the plate making section, the plate ejection section, etc. must be necessarily relocated above. Therefore, by securing a large space as described above, the overall height of the printing press is increased, resulting in an increase in the size of the stencil printing press and the paper feeding device,
The operability at the time of setting the original on the original reading unit may deteriorate.

Further, for example, the above-mentioned Japanese Patent Laid-Open No. 6-2711
24 or the latter technique described in Japanese Patent Laid-Open No. 6-271125 has the following problems. Certainly, the latter technique can meet the above-mentioned requirements, but has a problem that the mechanism is complicated and the cost is increased.

Further, the waiting time for feeding from the multi-sheet feeding table is short, but at the time of paper replenishment, when the cassette sheet feeding mode is set, the cassette is pulled out to feed the multi-sheets. After switching to the mode, the operation of replenishing the paper is required after the multi-sheet feed table is lowered.
When the image forming apparatus is a printing machine or a special stencil printing machine, as described above, there are many cases in which several thousand printed materials are printed from one original, and in such a case, the multi-sheet feeding table is loaded. The paper capacity is several thousand sheets (usually, the height of the printer body is usually set within 1 m in consideration of the improvement in operability, so it is limited to about 3000 to 4000 sheets). However, there are many cases where the paper is insufficient before printing starts, and it is necessary to replenish it. It is not always preferable from the viewpoint of operation including, but rather, it is preferable that the setting is made so that a certain amount of paper can be easily replenished within a range in which the waiting time until the start of feeding does not become too long.

Further, a sensor for detecting the presence / absence of a cassette is provided, and the multi-sheet feeding table is raised to the feeding position based on a signal of the presence / absence detection of the cassette from the sensor. The set may be incomplete because the user performs it, and a signal indicating no cassette may be output even though the cassette is mounted. Further, the sensor may be damaged by a rough operation of the user. In such a case, when the multi-sheet feeder is raised to the sheet feeding position, a member such as a cassette interferes with a member in the stencil printing apparatus, which may damage the apparatus.

Further, it is required that the cassette can be quickly and easily removed when switching from the cassette paper feeding mode to the multi-sheet paper feeding mode, and that the waiting time at the time of mode switching is short. , In the latter example,
No consideration is given to such points. In the present invention, in order to solve the above-mentioned problems, as will be described later, a cassette-dedicated drive mechanism for interrupt cassette sheet feeding is provided completely separately from the multi-sheet feeding table drive mechanism, and the mechanism is simplified. However, in such a paper feeding device, it is required that the cassette can be quickly and smoothly removed from the drive mechanism dedicated to the cassette when the multi-sheet feeding mode is set. To be done.

Therefore, an object of the present invention is to provide a sheet feeding device in an image forming apparatus as described below in order to solve the above problems. (1) According to the first and second aspects of the present invention, a so-called large-capacity sheet feeding device that selectively feeds sheets from the LCT and the interruption cassette with a single sheet feeding roller is used for cassette sheet feeding. It does not require a large paper feed unit, has a simple mechanism and structure that does not increase the size of the image forming apparatus and / or the paper feed apparatus, and has a space for feeding LCT above the paper feed roller. It is possible to realize a large-capacity sheet feeding device which does not require the height of the image forming apparatus and is not required.
In such a large-capacity sheet feeding device, the multi-sheet feeding table is prohibited from being raised when the cassette is mounted, and the image forming apparatus or the like is prevented from being damaged by the rise of the multi-sheet feeding table when the cassette is mounted. .

(2) According to the invention of claim 3, claim 1
Similar to the described invention, a large-capacity sheet feeding device that selectively feeds sheets from the LCT and the interruption cassette with a single sheet feeding roller, and does not require a large sheet feeding unit for cassette feeding. In addition, the image forming apparatus and / or the paper feeding device does not become large in size, and a simple mechanism / structure does not require a space for feeding the LCT at the upper part of the paper feeding roller. It is possible to realize a large-capacity paper feeding device that does not require the height of the device to be high, and further, in such a large-capacity paper feeding device, when the cassette is not completely mounted or when the cassette is mounted, The elevation of the multi-sheet feed tray is prohibited to prevent the image forming apparatus or the like from being damaged by the rise of the multi-sheet feed tray by mistake.

(3) In the invention according to claim 4, in addition to the object of (1), there is provided a large-capacity sheet feeding device capable of shortening the waiting time until the start of sheet feeding when switching to the interrupt cassette. To be realized.

(4) In the invention described in claim 5, in addition to the object of (1), the interrupt cassette can be promptly removed when switching from the cassette sheet feeding mode to the multi-sheet feeding mode. To realize a large-capacity sheet feeding device capable of shortening the switching time to the multi-sheet feeding mode.

(5) According to the invention of claim 6, in addition to the object of (1), when the interruption cassette is removed, the interruption cassette can be smoothly removed with less shock from the cassette drive mechanism to improve its operability. A large-capacity sheet feeding device capable of performing is realized.

(6) In the invention according to claims 7 and 8, in addition to the object of (5), when the interrupt cassette is removed,
The operation force of the interrupt cassette can be reduced, and this can be realized with a simple configuration.

(7) In the invention described in claim 9, when switching from the cassette sheet feeding mode to the multi-sheet feeding mode, after the interruption cassette is removed, the waiting time for feeding from the multi-sheet feeding table is shortened. (EN) A large-capacity sheet feeding device that can be used and can easily supply a large number of sheets to a sheet feeding table.

[0019]

In order to achieve the above-mentioned object, the invention according to claim 1 separates the stacked uppermost sheets one by one at a sheet feeding position and feeds them in a sheet conveying direction. In a paper feeding device in an image forming apparatus having a single paper feeding means at a paper feeding port, a casing forming an outer frame of the paper feeding device, and a paper feeding direction provided inside the casing. A pair of side fences that can be moved up and down in the housing between an upper fixed position of the housing and a lower fixed position of the housing for positioning both side edges of the paper in the orthogonal paper width direction. A frame supporting the side fence between the upper fixed position of the housing and the lower fixed position of the housing so that the side fence can be moved up and down, and the paper is loaded and lifted to face the paper feeding position. Paper tray that can be raised and lowered between the upper limit position and the lowest lowered position A fence elevating mechanism for elevating the side fence between the upper fixed position and the lower fixed position, and tray elevating drive means for moving the paper feeding tray between the upper limit position and the lower limit position, When the paper feed tray is lowered to the lower limit position, a cassette mounting space for mounting a paper feed cassette capable of storing a plurality of sheets is formed between the upper portion of the frame and the paper feeding means. And the paper feed cassette removably disposed in the cassette mounting space, cassette support means provided in the housing for detachably supporting the paper feed cassette, and housed in the paper feed cassette. A sheet stacking member capable of moving up and down between the upper limit position facing the sheet feeding position and the cassette lower limit position farthest from the upper limit position,
Paper stacking member driving means for selectively moving the paper stacking member up and down between the upper limit position and the cassette lower limit position;
A cassette presence / absence detection unit that detects whether or not the paper feed cassette is loaded in the cassette loading space, and a paper stacking member drive unit when the cassette presence / absence detection unit detects loading of the paper feed cassette. And the tray elevating and lowering drive means is prohibited from driving, and when the cassette presence / absence detecting means does not detect the mounting of the paper feed cassette, the tray elevating and lowering drive means is operated. And a control means for raising the paper tray.

According to a second aspect of the present invention, in the sheet feeding device of the image forming apparatus according to the first aspect, there is provided lower limit detecting means for detecting the lower limit position of the sheet feeding tray, and the control means comprises the cassette. When the presence / absence detection means detects the mounting of the paper feed cassette and the lower limit detection means detects the lower limit position of the paper feed tray, the paper stacking member driving means is operated to perform the paper stacking member. And the drive of the tray elevating drive means is prohibited, and when the paper feed cassette is not detected by the cassette presence / absence detecting means, the tray elevating drive means is operated for a predetermined time. And the lower limit position of the paper feed tray is not detected by the lower limit detection means, the tray elevating and lowering drive means is operated. After the paper tray is raised, the tray elevating drive means is operated to raise the paper feed tray for a predetermined time, and when the lower limit position of the paper feed tray is detected by the lower limit detection means, the tray It is characterized in that the raising / lowering drive means is used to stop the raising of the paper feed tray.

According to a third aspect of the present invention, an image having a single sheet feeding means for separating the uppermost stacked sheets at the sheet feeding position one by one and feeding them in the sheet conveying direction is provided. In a sheet feeding device of a forming apparatus, a casing forming an outer frame of the sheet feeding device and positioning of both side edges of the sheet in a sheet width direction orthogonal to the sheet conveying direction provided inside the casing. A pair of side fences that can be moved up and down in the housing between an upper fixed position of the housing and a lower fixed position of the housing; A frame body that is vertically movable between a lower fixed position of the body, and a feed mechanism that is vertically movable between an upper limit position where the sheets are stacked and raised to face the sheet feeding position, and a lowermost limit position where the sheets are lowered. The paper tray and the side fence, the upper fixed position and the lower part A fence elevating mechanism that elevates between a position and a position, a tray elevating drive unit that moves the paper feed tray between the upper limit position and the lower limit position, and the paper feed tray when the paper feed tray descends to the lower limit position, A cassette mounting space for mounting a paper feeding cassette capable of accommodating a plurality of sheets is formed between the upper portion of the frame and the paper feeding means, and the cassette mounting space is detachably disposed in the cassette mounting space. The paper feed cassette, a cassette support means provided in the housing for detachably supporting the paper feed cassette, and the paper stored in the paper feed cassette stacked to face the paper feed position. A paper stacking member that can move up and down between an upper limit position and a cassette lower limit position separated from the upper limit position, and a paper stacking unit that selectively moves the paper stacking member up and down between the upper limit position and the cassette lower limit position. Driving means, frame lower limit detecting means for detecting the frame lower limit position of the frame, cassette paper presence / absence detecting means for detecting the presence / absence of the paper stored in the paper feeding cassette, and frame lower limit detecting means Detects the lower limit position of the frame body of the frame body, and the cassette sheet presence / absence detection means detects the sheet in the paper feed cassette, the sheet stacking member driving means is used to load the sheet stacker. The member is lifted up so that the paper on the paper stacking member can be fed at the paper feed position, the driving of the tray elevating drive means is prohibited, and the frame lower limit detection means is the frame of the frame. When the lower limit position of the body is detected and the cassette sheet presence / absence detecting unit does not detect the sheet in the sheet feeding cassette, the tray raising / lowering driving unit is allowed to raise / lower the sheet feeding tray, and the tray raising / lowering drive is performed. Means Then, even if the raising / lowering operation of the sheet feeding tray is driven for a fixed time or the raising / lowering amount of the sheet feeding tray is raised / lowered by a fixed amount, the frame lower limit detecting means detects the frame lower limit position of the frame. When the state does not change from the detection state to the non-detection state, the control device includes a control unit that causes the tray elevating and lowering drive unit to stop the paper feed tray.

According to a fourth aspect of the present invention, in the sheet feeding device of the image forming apparatus according to the first or second aspect, the sheet feeding device is provided so as to cover an opening of the casing that opens into the cassette mounting space. An openable / closable cover for attaching / detaching a paper cassette and for loading / unloading a paper into / from the paper feed tray and the paper feed cassette; a cover open / close detection unit for detecting an open / closed state of the cover; Upper limit sheet detecting means for detecting the position of the uppermost sheet or the uppermost sheet stacked on the sheet stacking member, and the control means is configured to detect the cassette presence / absence by the sheet feeding cassette. Is detected and the cover open / closed detecting means detects the closed state of the cover, the paper stacking member driving means is operated to raise the paper stacking member. Characterized in that it allows the paper feed the sheet on the sheet stacking member in the sheet feeding position Te.

According to a fifth aspect of the present invention, in the sheet feeding device of the image forming apparatus according to the first or second aspect, the sheet feeding device is provided so as to cover an opening of the casing that opens into the cassette mounting space. An openable / closable cover for attaching / detaching a paper cassette and for loading / unloading a paper into / from the paper feed tray and the paper feed cassette; a cover open / close detection unit for detecting an open / closed state of the cover; Upper limit sheet detecting means for detecting the position of the uppermost sheet or the uppermost sheet stacked on the sheet stacking member, and the control means is configured to detect the cassette presence / absence by the sheet feeding cassette. Is detected and the cover opening / closing detecting means detects the open state of the cover, the sheet stacking member driving means is operated to lower the sheet stacking member. And wherein the Rukoto.

According to a sixth aspect of the invention, in the sheet feeding device of the image forming apparatus according to the fifth aspect, the control means drives the sheet stacking member driving means to lower the sheet stacking member at least. It is characterized in that the sheet stacking member is made to reach the cassette lower limit position.

According to a seventh aspect of the present invention, in the sheet feeding device of the image forming apparatus according to the fifth or sixth aspect, the sheet stacking member driving means is a driving means arranged in the casing, and A driving force transmission member for transmitting the driving force of the driving unit to the sheet stacking member, which is arranged on the inner surface and at a position where it does not interfere with the sheets stacked on the paper feed tray at maximum. A driven force transmitting member that selectively engages with the driving force transmitting member to move up and down the sheet stacking member is disposed in the paper feeding cassette, and the driving force transmitting member or the driven force transmitting member is disposed. To one of the two, transmitting the driving force in the direction of raising the sheet stacking member,
The sheet stacking member driving means is driven by the one-way clutch arranged so as to be in a loosening direction in which the driving force is not transmitted in a descending direction of the sheet stacking member. When lowering the member, the sheet stacking member driving means is used to lower the sheet stacking member for at least a fixed time longer than the time required for the sheet stacking member to reach the cassette lower limit position from the upper limit position. It is characterized by

According to an eighth aspect of the invention, in the sheet feeding device of the image forming apparatus according to the seventh aspect, the driving force transmitting member is provided with an arm for moving up and down the sheet stacking member. When the sheet stacking member has reached the lower limit position of the cassette and the paper feed cassette is removed from the cassette supporting means, the lower surface of the sheet stacking member that engages with the arm and the arm A gap structure is provided between the upper surface and the upper surface so as to allow the engagement between the driving force transmission member and the sheet stacking member to be released.

According to a ninth aspect of the present invention, in the sheet feeding device of the image forming apparatus according to the first or second aspect, a sheet surface for detecting the sheet surface height position of the upper portion of the sheets stacked on the sheet feeding tray. When the power source is turned on and the cassette presence / absence detection unit does not detect the mounting of the paper feed cassette, the control unit has a detection unit, and based on a signal from the paper surface detection unit, It is characterized in that the tray elevating drive means is used to stop the paper feed tray at the height position of the paper surface.

In the inventions according to claims 1 and 3, the pair of side fences are movable in the paper width direction within the housing, and the frame body holds the side fences in the paper width direction. It can be configured to be movably supported in this case, in which case different size papers
Each is surely positioned in the paper width direction.

[0029]

According to the first and second aspects of the present invention, with the above construction, when the tray elevating and lowering drive means lowers the paper feed tray, the frame body is selectively interlocked with the paper feed tray and is lowered,
A cassette mounting space for mounting a sheet feeding cassette capable of storing a plurality of sheets is formed between the upper portion of the frame and the sheet feeding means. Further, the side fence is supported by a frame so as to be able to move up and down between a fixed position on the upper part of the housing and a fixed position on the lower part of the housing, and is further urged by the urging means to reach the fixed position on the upper part of the housing. Has been done. Then, the tray elevating and lowering drive unit can stack and raise the sheets up to the upper limit position where the sheet feeding tray faces the sheet feeding position, and the sheets are reliably positioned in the sheet width direction by the side fence, The sheets are separated one by one by a single sheet feeding unit and fed to the image forming apparatus. Further, when the control means detects the mounting of the paper feed cassette by the cassette presence / absence detection means, the paper stacking member driving means is caused to raise the paper stacking member and the driving of the tray elevating / lowering means is prohibited, If the cassette presence / absence detecting unit does not detect the mounting of the sheet feeding cassette, the tray elevating / lowering driving unit is used to raise the sheet feeding tray so that the sheet feeding cassette is mounted or not mounted.
The drive of the tray elevating and lowering drive means is selectively switched on / off.

According to the third aspect of the invention, in addition to the actions of the first and second aspects of the invention, the control means further performs the following control operation. That is, the control means
When the frame lower limit detection unit detects the frame lower limit position of the frame and the cassette paper presence / absence detection unit detects the paper in the paper feed cassette, the paper stacking member driving unit is operated to move the paper stacking member. The paper is lifted up so that the paper on the paper stacking member can be fed at the paper feed position, the tray elevating and lowering drive means is prohibited from driving, and the frame lower limit detection means detects the frame lower limit position of the frame, and the cassette paper is fed. When the presence / absence detection means does not detect the paper in the paper feed cassette, the tray elevating / lowering drive means is allowed to elevate / lower the paper feed tray, and the tray elevating / lowering drive means is used to perform the elevating / lowering operation of the paper feed tray for a predetermined time or a predetermined time. Even if the paper tray is driven to move up and down by a certain amount, if the detection state of the frame lower limit position of the frame by the frame lower limit detection means does not change from the detected state to the non-detected state, the tray lift drive is performed. Take measures to stop the input tray. The Rukoto, even incomplete mounting of the paper feed cassette, is limited to a distance increase of the paper feed tray is small.

According to the invention described in claim 4, in addition to the operation of the invention described in claims 1 and 2, the following control operation is further performed by the control means. That is, the control means
When the cassette presence / absence detecting unit detects the mounting of the paper feeding cassette and the cover opening / closing detecting unit detects the closed state of the cover, the sheet stacking member driving unit is operated to raise the sheet stacking member to move the sheet. Since the paper on the stacking member can be fed at the paper feed position, when the paper cassette is installed and the cover is closed and preparations for starting paper feeding in the paper cassette are completed, the paper in the paper cassette is loaded. The member is raised so that the uppermost sheet is raised to the paper feeding position.

According to the invention of claim 5, in addition to the operation of the invention of claims 1 and 2, the control means further performs the following control operation. That is, the control means
If the presence / absence of the paper feed cassette is detected by the cassette presence / absence detecting unit and the open state of the cover is detected by the cover opening / closing detecting unit, the sheet stacking member driving unit is operated to lower the sheet stacking member. When the cover is opened to switch to the paper feed tray paper feed mode, the paper stacking member in the paper feed cassette starts to descend.

According to the invention of claim 6, in addition to the operation of the invention of claim 5, the control means drives the sheet stacking member drive means to lower the sheet stacking member and at least the sheet stacking member Since it is made to reach the cassette lower limit position, when the paper feed cassette is removed, the weight of the stacked sheets in the paper feed cassette is not added to the cassette drive mechanism, so the operation force when removing the paper feed cassette is small, and
The paper stacking member does not suddenly drop to the cassette lower limit position at the moment the paper cassette is removed, and the cassette drive mechanism is not impacted.

According to the seventh aspect of the invention, in addition to the actions of the fifth or sixth aspect of the invention, the control means drives the sheet stacking member drive means to lower the sheet stacking member. In the case of performing the above, at least when the cassette is removed by lowering the sheet stacking member by the sheet stacking member drive means for a fixed time longer than the time required for the sheet stacking member to reach the cassette lower limit position from the upper limit position, The sheet stacking member driving means rotates the driving force transmitting member in the loosening direction (sliding direction) of the one-way clutch.

According to the invention of claim 8, in addition to the operation of the invention of claim 7, when the sheet stacking member reaches the cassette lower limit position, the lower surface of the sheet stacking member engaging with the arm and the arm. By providing a gap structure between the upper surface and the driving force transmitting member in a range that allows the engagement between the driving force transmitting member and the sheet stacking member to be released, the sheet stacking member drive unit is driven when the sheet feeding cassette is removed from the cassette supporting means. By the upward pivoting motion of the arm that occurs when the connection between the means and the driven force transmission member is released, the arm does not interfere with the sheet stacking member, and at the same time, the sheet stacking member driving means moves the sheet. The load due to its own weight is not applied, and the pull-out operation force when removing the paper cassette does not increase.

According to the ninth aspect of the present invention, in addition to the functions of the first or second aspect of the present invention, the control means is capable of mounting the paper feed cassette by the cassette presence / absence detection means when the apparatus power is on. If it is not detected, based on the signal from the paper surface detecting means, the tray elevating and lowering driving means is operated to stop the paper feed tray at the paper surface height position. Thus, when the paper feed cassette is removed and the paper feed tray is switched to paper feed, the paper feed tray is positioned at the paper surface height position detected by the paper surface detection unit, that is, the upper portion of the paper stacked on the paper feed tray. Since it automatically stops at the side edge position, there is a gap between the top surface of the stacked paper on the paper feed tray and the paper feeding means of the image forming apparatus.
Since a fixed space is provided to supply about 500 to 1500 sheets of paper, the waiting time before the start of feeding does not become too long.

[0037]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. An embodiment according to the present invention will be described with reference to FIGS. 1 to 16. 1 to 10, reference numeral 1 indicates a stencil printing apparatus as an image forming apparatus. Reference numeral 1F indicates a main body frame of the stencil printing apparatus 1.
Reference numeral 100 denotes a sheet feeding device detachably arranged on one side of the main body frame 1F.

The sheet feeding device 100 is a sheet feeding roller 2 as a single sheet feeding means for separating the stacked uppermost sheets 6 one by one at the sheet feeding position and feeding them in the sheet conveying direction X. Movable frame 18 as a casing (case) that forms the outer frame of sheet feeding device 100, and positioning of both side edges of sheet 6 in sheet width direction Y that is provided inside movable frame 18 and is orthogonal to sheet transport direction X And a pair of side fences 20a and 20b (hereinafter sometimes referred to as "side fence pair 20a and 20b") that can be moved up and down in the movable frame 18 and that can move in the paper width direction Y. A frame that supports the pair of side fences 20a and 20b so as to be able to move up and down between an upper fixed position Pa of the movable frame 18 and a lower fixed position Pb of the movable frame 18 and to be movable in the paper width direction Y. body 8 (see FIGS. 4 and 10), a pair of springs 114 and 114 (pulling coil springs) as a biasing unit that biases the frame body 28 in an upward direction of the movable frame 18, and the sheets 6 are stacked. Then, it is possible to move up and down between the upper limit position P1 which rises and faces the sheet feeding position and the lower limit position P3 which is most lowered, and which lowers the frame 28 selectively in conjunction with its own lowering operation. Tray elevating drive device 1 as tray elevating drive means for moving the paper feed tray 7 between the paper tray 7 and the upper limit position P1 and the lower limit position P3.
0 (see FIG. 4), the paper feed tray 7 descends to the lower limit position P3, and a paper feed cassette 39 capable of accommodating a plurality of papers 6'is provided between the upper part of the frame 28 and the paper feed roller 2. When the cassette mounting space 39S for mounting (see FIG. 9) is formed, the paper feeding cassette 39 that is removably disposed in the cassette mounting space 39S and the paper feeding cassette 39 is detachably supported. A paper feed cassette attaching / detaching mechanism 47 (see FIG. 7),
It is mainly composed of a cassette tray elevating drive device 40 (see FIGS. 6 and 8) as a paper stacking member drive means for exposing the paper 6 ′ stored in the paper supply cassette 39 to the paper supply position.

The paper feeding device 100 is in the paper feeding position when the paper feeding cassette 39 is not mounted, and is in the paper feeding position when the paper feeding cassette 39 is mounted, and in the paper feeding position when the paper feeding cassette 39 is mounted. Two types of sheet feeding modes, that is, a cassette sheet feeding mode for feeding the sheet 6 ′ from the sheet feeding cassette 39, are selectively switched and executed by an electric control configuration described later. As will be described below, the paper feed tray 7 has a structure capable of stacking 3000 to 4000 sheets of paper 6 on the paper feed tray 7 at a time.
The LCT (Large-Capacity Feeding Table) is capable of loading a larger amount of paper than the maximum loading capacity (usually about 500 sheets) of the paper 6'that can be stored in. That is, the paper feeding device 100
Is a so-called LCT unit (large-capacity sheet feeding unit) having a structure in which an LCT is mounted and can be moved up and down.

The stencil printing machine 1 has a known structure similar to the structure described in Japanese Patent Application Laid-Open No. 5-229243, which has been proposed by the applicant of the present application. That is, reference numeral 5
Reference numeral 5 denotes an original reading unit, and reference numeral 54 denotes a plate making / plate making unit which is provided above the paper feeding device 100 and makes a stencil master (not shown) wound in a roll shape and feeds the plate to the printing drum 57. Reference numeral 53 is a print drum unit for printing on the paper 6 by winding a plate-making master (not shown) on the outer peripheral surface, and reference numeral 58 is the paper 6 or the paper feed cassette stacked on the paper feed tray 7 in the paper feeding device 100. Reference numeral 59 denotes a paper feeding unit for selectively feeding the paper 6 ′ stored in 39 to the print drum unit 53, and reference numeral 59 denotes a paper ejection unit for ejecting the printed paper 6a printed by the print drum unit 53 to the paper ejection tray 59a. Reference numeral 56 is the print drum 5
A plate discharge unit is provided opposite to the plate making / plate supplying unit 54 with 7 in between, and discharges the used stencil master stripped from the outer peripheral surface of the printing drum 57 to a plate discharging box (both not shown). Shown respectively. The print drum unit 53 corresponds to the image forming unit of the image forming apparatus.

1 to 15, the paper feed roller 2, the movable frame 18, and the pair of side fences 20a, 2 will be described below.
0b, the frame 28, the spring 114, the paper feed tray 7, the tray lift drive device 10, the paper feed cassette 39, the paper feed cassette attaching / detaching mechanism 47, and the cassette tray lift drive device 40 will be sequentially described. 3 and 4, the side fence pairs 20a and 20b are not shown in order to simplify the drawings.

The paper feed roller 2 is provided with a paper feed port 58A of the paper feed section 58.
Of the separating roller 51a, which is rotatably supported by the sheet feeding side plate on the side of the main body frame 1F, is swingably and rotatably provided at a free end portion of the arm via an arm (both not shown) on the rotation driving shaft. Has been. The paper feed roller 2 is, for example,
It has the same structure as the paper feed roller 5 described in Japanese Utility Model Publication No. 5-18342. Reference numerals 51a and 51b denote a pair of separation rollers,
Reference numerals 52a and 52b denote registration roller pairs, respectively.

A body table 1T is provided below the body frame 1F, and the body frame 1F is positioned and fixed to the body table 1T via a body frame fixing portion 1a. A fixed frame 26 provided in the lower portion of the sheet feeding device 100 is positioned and attached via a fixed frame attachment portion 27 on the lower right side of the main body table 1T in the figure. On the fixed frame 26, a pair of left and right fixed side plates 26a arranged on the left and right in the paper transport direction X,
26b (hereinafter sometimes referred to as "fixed side plate pair 26a, 26b") are fixed.

The movable frame 18 is supported above the fixed frame 26 so as to be movable in the paper width direction Y via a shaft member described later. The movable frame 18 has a substantially housing-like shape, and has a pair of side plates 18a and 18b (hereinafter also referred to as “side plate pair 18a and 18b”) provided on the left and right in the paper transport direction X and the front and rear in the paper transport direction X. Side plates 18c, 18d provided on the (hereinafter referred to as "side plate pair 18c, 18d")
Sometimes)), the side plate stays 18h fixed between the upper ends of the side plates 18a and 18b, and the side plates 18a and 18b.
It comprises a slide side plate 18g slidably provided in the paper transport direction X between the upper end central portions of a and 18b, and a side plate bottom 18e fixed to the lower part of the side plate pair 18a and 18b and the side plate pair 18c and 18d.

The slide side plate 18g is used for the paper feeding device 1.
At the time of the operation of 00, it is at the right position shown in FIGS. 1, 2 and 3, and the upper portion of the sheet feeding device 100 is closed to prevent noise leakage and ensure the safety of the user of the device. To do. On the other hand, when replenishing the paper 6 in the paper feeding tray 7 of the paper feeding device 100 or performing jam processing, the slide side plate 18g is slid to the left in FIGS. 1, 2 and 3 and the slide side plate 18g is slid and moved. By opening the cover 19 described later, the paper feeding device 1
The upper part of 00 is opened wider.

Fixed side plate pair 26a, 26b and side plate pair 18
a and 18b, as shown in detail in FIGS.
A movable frame guide shaft 31 and a movable frame drive shaft 30 that are arranged parallel to each other in the sheet width direction Y are provided so as to penetrate therethrough.

The movable frame drive shaft 30 comprises a pair of side plates 18.
It is rotatably supported on both lower portions of a and 18b through bearings 30a. Retaining rings 30b are attached to both ends of the bearing 30a supporting portion of the movable frame drive shaft 30, and the retaining ring 30b prevents the movable frame drive shaft 30 from moving in the sheet width direction Y from the pair of side plates 18a and 18b. ing. In the substantially central portion of the movable frame drive shaft 30,
A male screw 30d as shown in FIG. 11 is formed, and on the other hand, a guide holder 115 having a female screw that meshes with the male screw 30d is fixedly provided at a substantially central portion of the fixed frame 26. A horizontal movement motor 32 is fixedly installed near one end of the movable frame drive shaft 30 in the movable frame 18. The left and right moving motor 32 is composed of reduction gears 33, 30c.
The movable frame drive shaft 30 is connected to one end of the movable frame drive shaft 30 via a deceleration mechanism consisting of.

As shown in detail in FIG. 5, the paper feed tray 7 is substantially H-shaped in plan view, and is arranged inside the movable frame 18 as shown in FIGS. 10 and 11. Tray notches 7a and 7b are formed in the paper feed tray 7 at a substantially central portion in the paper width direction Y. In the lower left and right walls of each of the tray cutouts 7a and 7b in the paper feed tray 7 and in the lower left and right walls of the rear portion of the paper feed tray 7, they are formed parallel to each other in the paper width direction Y and long in the paper width direction Y. A pair of front and rear tray drive shafts 8a and 8b are fixedly installed.

The pair of side fences 20a, 20b is movable in the paper width direction Y in each of the tray cutouts 7a, 7b, and in a direction orthogonal to the paper conveyance direction X and the paper width direction Y, respectively. It is provided so as to be movable in a certain vertical direction Z.

At the front part of the pair of side fences 20a, 20b, side fence guide grooves 25, 25 are formed parallel to each other in the vertical direction Z and long in the vertical direction Z. These side fences are formed. Guide groove 25, 2
The tray drive shaft 8b penetrates through 5 through a guide sleeve 8g described later. The guide sleeve 8g has a flange-shaped portion formed to have an outer diameter larger than the width of the side fence guide groove 25 and guiding the tray drive shaft 8b in the up-and-down direction Z, the side fence guide grooves 25, 25, and the tray drive shaft 8 respectively.
and a sleeve portion which is loosely fitted between b and slidable in the paper width direction Y of the tray drive shaft 8b. On the other hand, as shown in FIGS. 5 and 11, at the rear part of the pair of side fences 20a, 20b, through holes 20h are formed to loosely fit the upper side fence moving axis 21 and the lower side fence moving axis 22, respectively. The pair of side fences 20a and 20b are guided slidably in the paper width direction Y. In this way, the tray notch portions 7a and 7b formed in the paper feed tray 7 are configured to prevent the movement of the pair of side fences 20a and 20b from being obstructed, and the pair of side fences 20a and 20b are
By sliding with respect to the tray drive shaft 8b, the side fence moving shaft upper side 21 and the side fence moving shaft lower side 22, the side edges of the paper 6 in the paper width direction Y can be positioned in accordance with the paper size to be used. it can.

Guide sleeves 20i and 20j, into which the side fence moving shaft 21 is loosely fitted, are fixedly provided inside the through holes 20h of the pair of side fences 20a and 20b. The guide sleeves 20i and 20j are movable on the side fence moving shaft 21 through through holes (not shown) formed in the guide sleeves 20i and 20j. A female screw is formed in each of the guide sleeves 20i and 20j in a direction substantially perpendicular to the axial direction of the side fence moving shaft 21, and a set screw 20k is screwed to the female screw. Therefore, as described above, after the pair of side fences 20a and 20b are moved in the paper width direction Y to position the paper 6 in the paper width direction Y,
By screwing the setscrew 20k, the guide sleeves 20i and 20j are fixed to the positioned position on the side fence moving shaft 21.

Side plate pair 18a, 18b of the movable frame 18
As shown in detail in FIGS. 4 and 10, the drive shaft guide groove formed in the up-down direction Z is longer than the side fence guide groove 25 for guiding the tray drive shafts 8a and 8b in the up-down direction Z. 9a and 9b are formed parallel to each other. Drive shaft guide groove 9 in the pair of side plates 18a, 18b
Between the a and the drive shaft guide groove 9b, a side fence moving shaft upper side 21 and a side fence moving shaft lower side 22 are provided in the vertical direction Z.
A moving shaft guide groove upper portion 23 and a moving shaft guide groove lower portion 24, which are formed shorter than the side fence guide groove 25 in the up-and-down direction Z, are formed to guide each other.

The frame 28 is composed of the side fence moving shaft upper part 21, the side fence moving shaft lower part 22, and a pair of connecting members 111a and 111b described later.

4, 10, 11 and 12, each end of the side fence moving shaft upper portion 21 penetrating both moving shaft guide grooves 23 is moved up and down along the outer wall of each side plate pair 18a, 18b. A pair of left and right connecting members 111a and 111b provided so as to be movable in Z (hereinafter referred to as "connecting member pair 1").
11a, 111b "). Similarly, each end of the side fence moving shaft lower 22 penetrating the both moving shaft guide grooves 24 is fixed to each lower end of the connecting member pair 111a, 111b. As described above, the frame body 28 constitutes one small frame by the above-mentioned four constituent members, that is, the side fence moving shaft upper side 21, the side fence moving shaft lower side 22, and the connecting member pairs 111a and 111b.

The pair of springs 114, 114 includes a pin 113 planted in each of the side plates 18a, 18b above the moving shaft guide groove 23 and a convex portion formed substantially in the center of the connecting member pair 111a, 111b. Pin 11 planted in 111c
It has been passed over between 2 and each. In this way, the frame body 28 can be raised and lowered within the range of the opening of the moving shaft guide groove upper part 23 and the moving shaft guide groove lower part 24, and is moved upward of the movable frame 18 by the pair of springs 114, 114. It is biased in the direction. Therefore, the pair of side fences 20a and 20b are
The frame body 28 is always urged upward. Therefore,
As the paper feed tray 7 rises, the upper part of the side fence moving shaft lower part 22 forming a part of the frame body 28 is in contact with the lower surface of the paper feed tray 7, and the frame body 28 goes up, and the side fence moving shaft upper part 21, The ascent of the side fence moving shaft lower 22 stops when the moving shaft upper side 21 and the moving shaft lower side 22 come in contact with the upper ends of the moving shaft guide groove upper 23 and the moving shaft guide groove lower 24 respectively, and the side fence pair 20a, 20b is 1 and 2, it will rise to the position shown by the solid line and stop. Then, when the remaining amount of the paper 6 on the paper feed tray 7 becomes small and the paper feed tray 7 is further raised, the tray drive shaft 8b slides in the side fence guide groove 25, so that the paper feed tray 7 7 is side fence vs. 2
Since it rises relative to 0a and 20b, even the last one of the sheets 6 stacked on the sheet feeding tray 7 can be brought into contact with the sheet feeding roller 2 and reliably fed.

As described above, the fence elevating mechanism for elevating the pair of side fences 20a, 20b between the upper fixed position Pa and the lower fixed position Pb of the pair of side plates 18a, 18b includes the pair of springs 114, 114 and the frame. It forms a part of the body 28 and is selectively interlocked with the lowering operation of the paper feed tray 7 and engages with the lower surface of the paper feed tray 7 to form a pair of side fences 20a, 20a.
It is composed of a side fence moving shaft lower part 22 as a fence moving member for lowering b.

In this way, the side fence pair 20a, 2
0b, as the frame 28, as the paper feed tray 7 is raised,
Since it rises within a certain range between the upper fixed position Pa and the lower fixed position Pb, a special drive mechanism for exclusively raising the pair of side fences 20a and 20b is unnecessary. Then, the frame 28 including the pair of side fences 20a and 20b
Since the portion is simple in construction and small in size and light in weight, it is not necessary to increase the biasing force of the spring 114, and when the frame body 28 descends in conjunction with the lowering operation of the paper feed tray 7, it will be described later. Since the load on the tray raising / lowering motor 11 is small, the tray raising / lowering motor 11 can be downsized. Further, when the paper feed tray 7 is lowered to the lower limit position P3 shown in FIG. 6 when the paper feed cassette 39 is used, the frame body 28 itself is also pushed down in association with the paper feed tray 7 and the upper portion of the frame body 28 and the paper feed tray are fed. Paper feed cassette 39 between roller 2
Cassette mounting space 39S for mounting the cassette (see FIG. 9)
However, in this case as well, a special drive mechanism for exclusively lowering and driving the frame 28 is unnecessary.

As shown in FIG. 9, each side plate 18a, 18b
Lower cover parts 143 and 144 are attached to the lower outer part of the rear part to cover the lower outer parts of the rear parts of the side plates 18a and 18b, respectively. Above the lower covers 143 and 144, upper cover 141 and 142 in the form of stepped casings are attached to cover the outer upper parts of the rear portions of the side plates 18a and 18b, respectively.

As shown in FIGS. 9 and 22, the side plate 18d
Above the cover 141 and the cover 142 and above the stepped portion above the stepped portion, an opening that opens to the cassette mounting space 39S is provided with a cover 19 that covers the opening in an openable and closable manner. The cover 19 is the paper feed cassette 3
9 can be attached / detached, the paper feed tray 7 and the paper feed cassette 39
It is opened and closed when replenishing the sheets 6 and 6 ′ with each other, or when performing jam processing at the time of feeding. The cover 19 can rotate about 100 ° in the right direction of the thick arrow shown in FIG. 9 with a support shaft 19a interposed in a support bearing formed between the cover 19 and a support plate attached to the side plate 18b as a fulcrum. is there. On the inner wall of the base portion of the cover 19 near the support shaft 19a, approximately L
A character-shaped sensor operating piece 19b is fixedly provided. A convex actuating portion 19c is formed at the tip of the sensor actuating piece 19b, and rotates when the cover 19 is opened and closed. Cover 1
As indicated by the solid line in FIG. 9, the operating portion 19c of the sensor operating piece 19b presses the actuator portion of the cover opening / closing detection sensor 92 to turn on the cover opening / closing detection sensor 92 to open / close the cover 19. Is detected.

As shown in detail in FIG. 4, the tray elevating and lowering drive device 10 includes a side plate 18 near the lower portion of the drive shaft guide groove 9a.
The tray lifting motor 11 fixed to the motor mounting member 18f integrally formed with a, the worm 12 fixed to the output shaft end of the tray lifting motor 11, the side plate pair 18a,
Drive pulley shafts 15s fixed to both ends of a drive pulley shaft 15s pierced through 18b and rotatably supported by side plate pairs 18a and 18b, a drive pulley gear 14 fixed to the drive pulley 15, and a worm on the side plate 18a. 12 and a drive pulley gear 14 and an idler gear 13b meshing with the drive pulley gear 14, and a worm wheel 13a meshed with the worm 12 and fixed integrally coaxially with the idler gear 13b to rotate integrally with the idler gear 13b. When,
The intermediate pulleys 16a to 16e rotatably arranged at predetermined positions of the pair of side plates 18a and 18b, and the drive pulley 1
5 and the intermediate drive pulleys 16a to 16e, the drive belt 17 and belt stays 17a and 17b that are fixed to the drive belt 17 and fixed to the tray drive shafts 8a and 8b. Composed. Tray lifting motor 11, worm 12, drive pulley gear 1
4, the components of the tray lift drive device 10 except the idler gear 13b and the worm wheel 13a are omitted in FIG.
It is also provided on the side.

The tray raising / lowering motor 11 is a DC motor which can be driven to rotate clockwise and counterclockwise. The drive belt 17 is a toothed timing belt, and the drive pulley 15 and the intermediate pulleys 16a to 16e also have a well-known toothed structure. The tray lifting motor 11 is
It is electrically connected to a control means 60 described later via a tray elevating motor drive circuit 71 shown in FIG. 16, and is controlled by the control means 60 as follows.

With the above configuration, when the tray lifting motor 11 is driven in the clockwise direction in the normal direction, the worm 1
2, the worm 12 and the worm wheel 1 so that the drive pulley 15 rotates clockwise through the worm wheel 13a, the idler gear 13b, and the drive pulley gear 14.
If the twisting direction of the tooth profile of 3a is set, both ends of the tray drive shafts 8a and 8b fixed to the drive belt 17 by the rotation of the tray lifting motor 11 in the clockwise direction, that is, the paper feed tray 7 is moved at a constant speed. To be done. On the contrary, when the tray elevating motor 11 is reversely driven in the counterclockwise direction, the paper feed tray 7 is lowered at a constant speed. In this way, the paper feed tray 7 is moved up and down in the up and down direction Z while maintaining a substantially horizontal state in parallel with the paper transport direction X. The mesh between the worm 12 and the worm wheel 13a depends on the weight of the paper feed tray 7 and the drive pulley gear 14 and the idler gear 1
Since the rotation of the tray elevating motor 11 is stopped, the paper feed tray 7 can be stopped at that position and the paper feed tray 7 can be held at that position because the rotation of the tray lifting motor 11 is stopped.

With reference to FIGS. 6 to 9 and FIGS. 12 to 15, the structure relating to the sheet feeding cassette 39 and the operation when the sheet feeding cassette 39 is mounted on the sheet feeding device 100 will be described. The paper feed cassette 39 includes a substantially housing-shaped sheet storage case 39b without an upper lid, and a sheet stacking plate 41 serving as a swingable sheet stacking member disposed substantially in the front half of the bottom wall of the sheet storage case 39b. And a paper storage case 39b below the paper stacking plate 41
Of the arm shaft 43 rotatably supported on the bottom wall of the paper, and a drive force transmission member, which will be described later, integrally attached to one end of the arm shaft 43 to selectively engage and elevate the sheet stacking plate 41. An arm shaft gear 44 as a driven force transmitting member,
It is mainly configured by a stacking plate elevating arm 42 as an arm fixed to the arm shaft 43.

In FIG. 8, reference numeral 39a is an arm storage recess formed in the bottom wall of the paper storage case 39b for storing the stacking plate elevating arm 42 when not feeding.
Reference numeral 39c is a stopper formed inside the front wall of the paper storage case 39b for receiving the free end portion of the stacking plate elevating arm 42 and determining the lowest position of the paper stacking plate 41. The paper storage case 39b is made of a synthetic resin such as acrylonitrile butadiene styrene copolymer (ABS), and the paper loading plate 41 and the loading plate elevating arm 42 are made of steel plates. Guide grooves 49 are formed on both outer side walls of the paper feed cassette 39 to engage the cassette guides 48a and 48b and slide the paper feed cassette 39 in the paper transport direction X and in the opposite direction. As shown in FIG. 13, the guide groove 49 may be formed by a rib 49a formed on the side wall of the paper storage case 39b. Such ribs 49a are provided on the cassette guides 48a and 48b.
The insertion opening side of the guide groove 49 into which is inserted has an upward and downward arcuate inclination to form a guide insertion opening portion 49b in which the insertion opening is widened, and the cassette guides 48a, 48
b is easy to insert.

Inside the paper feed cassette 39, a pair of left and right side fences 121Ka and 121Kb are provided.
It is movable in the paper width direction Y along a guide groove 123K formed in the bottom wall of the paper storage case 39b so as to be long in the paper width direction Y. These side fences 121K
The a and 121 Kb can be fixed at arbitrary positions within the range of the guide groove 123K by a position fixing mechanism (not shown), and the paper 6 ′ in the paper width direction Y can be fixed.
Both side edges of the are positioned. In FIG. 13, reference numeral 122K is a paper end plate, and insertion holes 12 are formed at predetermined intervals in the paper transport direction X on the bottom wall of the paper storage case 39b depending on the paper 6'used.
It is used by inserting in 4K
It plays the role of a stopper on the rear end side. Reference numeral 125
K ₁ is an actuator for a cassette size detection sensor, and is a cassette paper size detection sensor group 89 (a light-emitting / light-receiving transmissive optical sensor shown in FIG. 23 and described later) arranged on the side plate 18b side not shown in FIG. The sheet size of the sheet placed on the sheet feeding cassette 39 can be detected. The cassette size detection sensor actuator can be fixed to the paper storage case 39b by the user according to the size of the paper to be used, by fastening with a screw or using elasticity. The actuator 125K ₂ shown in FIG. 23 is for detecting another sheet size.

As shown in FIG. 8, the sheet stacking plate 41 has its base end attached to a swing shaft 41s rotatably supported on the bottom wall of the sheet storage case 39b, and has a free end. Swings in the up-and-down direction Z around the swing shaft 41s.
That is, the sheet stacking plate 41 stacks the sheets 6 ′ stored in the sheet feeding cassette 39 and faces the sheet feeding position at the upper limit position P.
1 and the lower limit position P of the cassette that has descended most from the upper limit position P1
It is possible to move up and down with c. Paper storage case 39
The height of the b in the ascending / descending direction Z is set to about 50 to 80 mm. The cross section of the stacking plate elevating arm 42 has a substantially V shape, and the bent portion of the stacking plate elevating arm 42 has a curved shape.
Engage with the free end of 1. The paper feeding cassette 39 is a so-called interrupt type cassette, and is used when it is desired to change the paper size in the middle and / or when it is desired to change to colored paper, and usually about 500 sheets of paper 6 ′.
Can be loaded and stored. The arm storage recess 3
The shape of 9a is not limited to this, and may be a shape in which the concave portion is notched.

The paper feed cassette attaching / detaching mechanism 47 is composed of a pair of left and right cassette guides 48a and 48b fixed to the upper inner walls of the side plates 18a and 18b of the movable frame 18, and a guide groove 49 of the paper feed cassette 39. The paper feed cassette attaching / detaching mechanism 47 guides the paper feed cassette 39 when the paper feed cassette 39 is attached, and
Position it so that it does not come into contact with other objects. The cassette guides 48a and 48b have a function of cassette supporting means for detachably supporting the paper feeding cassette 39. Paper cassette 3
9, the cassette guides 48 a, 4 via the guide groove 49.
At the position completely inserted in 8b, as shown in FIG. 14, the drive shaft guides 48c and 48d provided inside the pair of side plates 18a and 18b are connected to the arm shaft 43 of the sheet feeding cassette 39 (indicated by a virtual line in the drawing). Both end portions (shown) are adapted to engage with each other. In the figure, only the drive shaft guide 48c fixed to the side plate 18b is shown, but a drive shaft guide 48d on the opposite side is symmetrically fixed to the side plate 18a. Both end portions of the arm shaft 43 are guided by the inclined portions 48e formed on the drive shaft guides 48c and 48d when the paper feed cassette 39 is inserted and attached, and the drive shaft guides 48c and 48c
It is inserted in the R-shaped part of 48d. As a result, the arm shaft 43 is reliably positioned when the paper cassette 39 is inserted and mounted, and the lifting arm drive gear 45, which will be described later, and the arm shaft gear 44 fixed to the shaft end of the arm shaft 43 mesh with each other. The positional relationship can be ensured with high accuracy, and a reaction force due to the weight of the sheet 6'when the arm shaft 43 is rotated can be received, and the meshing positional relationship can be maintained during driving.

The cassette tray elevating / lowering device 40 includes a cassette tray elevating / lowering motor 46 as a driving means fixedly provided on the upper inner wall of the side plate 18a and a cassette tray elevating / lowering motor 4.
6, an elevating arm drive gear 45 as a driving force transmitting member that is fixed to the output shaft end of 6 and that selectively meshes with the arm shaft gear 44 when the paper feed cassette 39 is attached and detached, and is provided on the paper feed cassette 39 side. The arm shaft gear 44, the one-way clutch 44a built in the arm shaft gear 44, and the arm shaft 43
A stacking plate elevating arm 42 and a sheet stacking plate 41. The cassette tray elevating and lowering drive device 40 has a function of a sheet stacking member drive means for selectively elevating and lowering the sheet stacking plate 41 between the upper limit position P1 and the cassette lower limit position Pc. That is, the sheet stacking member driving means is arranged at a position where the driving means arranged in the housing and the innermost surface of the housing do not interfere with the maximum stacked sheets on the paper feed tray. It can be said that it is composed of a driving force transmission member for transmitting the driving force of the above to the sheet stacking member.

The cassette tray raising / lowering motor 46 is a DC motor which can be driven to rotate clockwise and counterclockwise. The cassette tray raising / lowering motor 46 is electrically connected to the control means 60 via the cassette tray raising / lowering motor drive circuit 72 shown only in FIG.

The elevating arm drive gear 45 is used for the paper feeding device 10.
When 0 is viewed from above, it is arranged at the position shown in FIG. In the figure, paper 6 indicated by a virtual line is a paper stacked on the paper feed tray 7. Side fence pair 20a,
The sheet 20b spreads to the position shown in FIG.
The maximum width of the paper is the position shown by the phantom line in FIG. The elevating arm drive gear 45 is arranged on the outer side of the maximum paper width in the width direction, and when the paper is fed using the paper feed tray 7.
In the process in which the uppermost sheet 6 of the stacked sheets 6 abuts the sheet feeding roller (not shown in FIG. 12), the elevating arm drive gear 45 does not interfere with one side edge of the sheet 6. It is possible to feed paper by the paper feed tray 7. In this way, the mechanism for raising and lowering the sheet stacking plate 41 of the sheet feeding cassette 39 (the arm shaft 43, the stacking plate raising and lowering arm 42) and the arm shaft gear 44 as a driven force transmitting member are provided.
On the main body side (side plate 18a) of the sheet feeding device 100, an elevating arm drive gear 45 as a driving force transmitting member is provided at the above-mentioned position, and the gears 44 and 45 mesh with each other to stack sheets in the sheet feeding cassette 39. Since the plate 41 is driven up and down, it is not necessary to dispose a sheet stacking plate drive member (for example, a drive arm or the like) between the side plates 18a and 18b, and the sheet feeding by the sheet feeding tray 7 can be performed without interference. The so-called interrupt cassette makes it possible to feed paper with the same paper feed roller. Further, according to such a mechanism, the paper feed cassette 3
A large mechanism for raising and lowering the entire sheet cassette mounting portion is not required for raising and lowering the sheet 6'in 9 and a simple mechanism can be used. Therefore, the apparatus can be downsized, lightened, and assembled. It is possible to facilitate the sex.

The one-way clutch 44a has a driving force transmitting rotational direction (tightening direction) when the arm shaft gear 44 is rotated clockwise in FIGS. 6, 8 and 15.
When the arm shaft gear 44 is rotated counterclockwise, the driving force is transmitted so as to rotate the arm shaft 43 in the clockwise direction. It is arranged so as not to transmit a driving force to 43 and to idle.

This operation will be described in detail with reference to FIG. In the figure, the paper feed cassette 3 indicated by a virtual line
When 9 is inserted from the right side to the left side in the direction of the thick arrow in the figure, before the arm shaft gear 44 and the lifting arm drive gear 45 reach the regular meshing position, the arm shaft gear 44 and the lifting arm drive gear 45 Teeth contact each other. In this state, when the paper feed cassette 39 is pushed to the normal mesh position, if the one-way clutch 44a is not provided, the arm shaft gear 44 and the arm shaft 43 try to rotate counterclockwise. The loading plate elevating arm 42 is in the position shown in the figure and cannot rotate due to its own weight. Alternatively, even if a slight vibration is applied to the paper feed cassette 39 and the arm shaft 43 is set to be slightly rotated clockwise, when the paper 6 ′ is placed on the paper stacking plate 41, the The stacking plate elevating arm 42 cannot move due to the weight of the sheet 6 ′. If the paper feed cassette 39 is forcibly pushed inward in such a state, the gears 44, 45 and parts where these gears are attached may be damaged. On the other hand, the one-way clutch 44a as described above is attached to the arm shaft gear 44
, The arm shaft gear 44 is loosened counterclockwise with respect to the arm shaft 43 and idles in the rotational direction. Therefore, when the teeth of the gears 44 and 45 come into contact with each other, the paper feed cassette 39 is inserted to the regular meshing position. The arm shaft gear 44 idles and the lifting arm drive gear 45
It engages while engaging in a motion that relatively rolls around. Therefore, even when the paper feed cassette 39 is inserted, there is no resistance due to the contact between the teeth of the gears 44 and 45, the paper feed cassette 39 can be smoothly inserted to the regular meshing position, and the teeth of the gears 44 and 45 are damaged. And so on. In order to raise the sheet stacking plate 41, the arm shaft gear 44 is rotated in the clockwise direction. In this direction, the driving force is transmitted to the arm shaft 43 in the closing direction of the one-way clutch 44a. The loading plate 41 can be raised.

The one-way clutch 44a is not limited to be built in the arm shaft gear 44 as a driven force transmission member, but instead of being built in the arm shaft gear 44, a lifting arm drive gear as a driving force transmission member. You may make it built in 45.

With reference to FIGS. 1 to 16, an electrical control configuration for controlling the operation of the above-described sheet feeding device 100 will be described. In order to simplify the drawing, the upper limit detection sensor 3 is omitted in FIG. 8, and in FIGS. 1 to 4 and 6, the upper limit detection sensor 3, the intermediate detection sensor 4, the paper surface detection sensor 95, and The lower limit detection sensor 5 and the like are simplified and shown as a model at any time.

As shown in FIG. 9, the tray lowering key 67 as the tray lowering setting means is arranged on the operation console near the cover 19 of the sheet feeding device 100. Tray down key 6
Reference numeral 7 is for opening the cover 19 and performing a pressing operation, and sets the descending amount of the paper feed tray 7 by pressing for a predetermined time. Tray lowering key 67
A lamp 94 as an illuminating device for illuminating the pressing portion is built in the pressing portion. Lamp 94
Is turned on only when necessary, as described later, via the descending key pressing portion illumination drive circuit 93 in the sheet feeding device operation panel 141P.

The left / right moving key (left) 82 and the left / right moving key (right) 81 are arranged on a paper feeding device operation panel 141P provided on the cover 141, as shown in FIG. The left and right movement keys (left) and (right) 82 and 81 have a function of selectively switching the left and right movements of the movable frame 18 in the paper width direction Y and activating it, and pressing any one of the pressing portions for a predetermined time. As a result, it has a role of a movable frame movement setting means having both functions of setting the amount of lateral movement. Left and right movement keys (left), (right) 82, 81
Pressing portions for selectively switching the left and right movements of the movable frame 18 in the paper width direction Y are arranged opposite to each other. The amount of movement is set so that it can move at least 10 mm to the left and right. The left / right movement keys (left), (right) 82, 81 are provided on the sheet feeding device operation panel 141P near the left / right movement keys (left), (right) 82, 81.
A left / right movement amount indicator 83 is arranged to display the amount of movement leftward or rightward in the paper width direction Y by depressing any one of them. The movement amount of the movable frame 18 is displayed on the left / right movement amount display 83 provided on the sheet feeding device operation panel 141P as shown in FIG. The horizontal movement amount display unit 83 is provided with a scale display portion for displaying the movement amount of the movable frame 18. On the other hand, at a predetermined position of the main body frame 1F, a pointer portion for displaying a scale on the scale display portion is fixed, and as the movable frame 18 moves, how much the movement amount has become. It is supposed to inform you.

The left and right movement keys (left), (right) 82,
81 is not limited to this, and for example, only one switch having a well-known seesaw-type structure in which push-down portions corresponding to the both keys face each other and are integrally formed may be provided.

When it is desired to move the papers 6, 6'on the paper feed tray 7 or in the paper feed cassette 39 to the left or right, the left / right moving keys (left) and (right) 82, 81 correspond to the desired direction. When the left / right movement key is pressed, a command signal for rotating the left / right movement motor 32 in the normal direction or the reverse direction is transmitted from the control means 60, which will be described later, to the left / right movement motor drive circuit 73 of the left / right movement drive device 70 to move the left / right movement. The motor 32 is rotationally driven, whereby the movable frame drive shaft 30 is rotated via the speed reduction mechanism, and the movable frame 18 is moved leftward or rightward in the sheet width direction Y with respect to the fixed frame 26 by the screw mechanism. The horizontal movement amount is displayed on the left / right movement amount display 83.
Then, when the amount of movement reaches a desired amount, the pressing operation of the left / right movement key is stopped, whereby the rotation drive of the left / right movement motor 32 is stopped and the movement of the movable frame 18 is stopped. In this way, the sheets 6 and 6'are moved in the sheet width direction Y with respect to the stencil printing apparatus 1 as an image forming apparatus. Therefore, the sheets 6 and 6'are moved in the sheet width direction Y together with the movable frame 18 with respect to the main body frame 1F, and the image position in the sheet width direction Y during printing can be adjusted.

Upper limit detection sensor 3 as upper limit detection means
When the paper feed tray 7 is lifted or the paper stacking plate 41 of the paper feed cassette 39 is lifted (swing), any one of the uppermost papers 6 and 6 ′ placed on the paper feed roller 2 is appropriate for the paper feed roller 2. When the paper feed roller 2 is lifted to a proper paper feed position for feeding by contacting with a certain pressure, that is, one of the uppermost sheets 6 and 6'does not feed the paper feed roller 2. An ON signal is output when the upper limit position P1 is set to a proper sheet feeding position for sheet feeding, and an OFF signal is output otherwise. The uppermost sheet 6 (or sheet 6 ') can be fed by the sheet feed roller 2 only when the upper limit detection sensor 3 outputs an ON signal. The upper limit detection sensor 3 is a known transmissive (light-shielding) type optical sensor having a light emitting portion and a light receiving portion, and is freely swingable on the uppermost sheet 6 (or sheet 6 ′) stacked on the sheet feeding tray 7. The arm is provided with an abutting piece that comes into contact with the abutting piece, and a light-shielding plate provided in conjunction with the abutting piece performs a light-shielding operation between the light-emitting portion and the light-receiving portion, whereby the uppermost sheet 6 (Or the upper limit position P1 of the sheet 6 ') is detected. The upper limit detection sensor 3 is provided on the main body frame 1F near the paper feed roller 2. The upper limit detection sensor 3 has, for example, the same configuration as the optical sensor PS2 shown in FIG. 3 and the like described in JP-A-2-265825.

Lower limit detection sensor 5 as lower limit detection means
Detects the lower limit position P3 of the paper feed tray 7, and is arranged at a predetermined position inside the side plate 18a as shown in FIGS. The lower limit detection sensor 5 is a well-known reflective optical sensor having a light emitting portion and a light receiving portion. The lower limit detection sensor 5 detects that the paper feed tray 7 occupies the lower limit position P3 by projecting light from the light emitting unit on one side surface of the paper feed tray 7 and detecting the reflected light by the light receiving unit. To do. The lower limit detection sensor 5 outputs an ON signal only when the paper feed tray 7 occupies the lower limit position P3, and otherwise,
Output an off signal.

Intermediate detection sensor 4 as intermediate detection means
Is for detecting the intermediate position P2 of the paper feed tray 7 in order to stop the paper feed tray 7 at a predetermined intermediate position P2 between the upper limit position P1 and the lower limit position P3. As shown in FIG. 4, it is arranged at a predetermined position inside the side plate 18a. The intermediate detection sensor 4 is a known reflective optical sensor having a light emitting portion and a light receiving portion. The intermediate detection sensor 4 detects that the paper feed tray 7 occupies the intermediate position P2 by projecting light from the light emitting unit on one side surface of the paper feed tray 7 and detecting the reflected light by the light receiving unit. To do. In the intermediate detection sensor 4, the paper feed tray 7 has an intermediate position P2.
The ON signal is output only when the signal is occupied, and the OFF signal is output otherwise. The intermediate detection sensor 4 is a lower limit detection sensor 5
Is arranged inside the side plate 18a 100 mm above the arrangement position.

Paper surface detection sensor 95 as paper surface detection means
Is the upper limit position P1 as shown in FIGS. 1, 2 and 6.
In order to stop the paper feed tray 7 at a paper surface detection position P4 corresponding to a predetermined paper surface height position between the intermediate position P2 and the intermediate position P2, the paper feed tray 7 is lifted or stopped in the side fence pair 20a, 20b. The side edge of the upper portion of the sheets 6 stacked on top (the upper surface of the stacked sheets) or the other side surface of the paper feed tray 7 is detected. The paper surface detection sensor 95 is a well-known reflective optical sensor having a light emitting portion and a light receiving portion, which is arranged on the side wall of the side fence 20b (or the side fence 20a). The paper surface detection sensor 95 is a side fence pair 2.
Paper feed tray 7 that moves up and down or stops in 0a and 20b
Side edge of upper part of paper 6 stacked on top (top of stacked paper)
Alternatively, the ON signal is output only when light is emitted from the light emitting unit to the other side surface of the paper feed tray 7 and the reflected light is detected by the light receiving unit, and the OFF signal is output otherwise.

Side fence 20 of paper surface detection sensor 95
b (or side fence 20a) is attached to the side wall at the upper fixed position Pa where the pair of side fences 20a and 20b is most raised, the upper surface of the paper 6 stacked on the paper feed tray 7 and the paper feed roller. About 100m between 2 and
When the space (distance) of about m is generated, the number of sheets of paper 6 is 5
00 to 1500 sheets (depending on paper thickness, 55 kg of fine quality
It is determined in the up-and-down direction Z of the side fence 20b or the side fence 20a so that there is a gap in which about 1,000 sheets of paper can be stacked.

The side fence frame lower limit detection sensor 83 as the frame lower limit detection means is fixed by a bracket 18h fixed to the outside of the side plate 18a of the movable frame 18, as shown in FIG. Connecting member 111a of frame 28
A sensor detection piece 111d is provided in a part of
The paper feed tray 7 is lowered to near the lower limit position P3, and the frame 28
When is lowered to near the lower fixed position Pb, as shown in FIG. 25, when the sensor detection piece 111d enters between the light emitting and light receiving parts of the side fence frame lower limit detection sensor 83 and is shielded, the side fence frame lower limit detection sensor 83 is turned on. Output signal,
It is detected that the frame body 28 is lowered.

As shown in FIG. 11, the left / right position left limit detection sensor 84 and the left / right position right limit detection sensor 85 are fixed to the lower inner walls of the pair of side plates 18a, 18b near both ends of the movable frame drive shaft 30. The movable frame 18 moves integrally with the movable frame 18 as the movable frame 18 moves in the sheet width direction Y. The actuator portions 84a, 85a of the left / right position left limit detection sensor 84 and the left / right position right limit detection sensor 85 are part of the fixed frame 26 (in the case of the drawing, fixed side plate pairs 26a, 26) when a certain amount of movement is performed.
It is arranged so as to contact with the outer wall of the upper end of b) to turn on, and when the movable frame 18 moves by a certain amount or more,
It is detected that the left or right movement limit position has been reached.

As shown in FIG. 5, the tray paper width detection sensor group 86 is arranged substantially in the center of the lower side fence moving shaft 22, and detects the paper width size of the paper 6 in the paper width direction Y. Have a function. Tray paper width detection sensor group 8
6 is four tray paper width detection sensors 86a, 86b,
86c and 86d (hereinafter sometimes simply referred to as "tray paper width detection sensors 86a to 86d"). As shown in detail in FIGS. 5 and 24, an angle-shaped sensor bracket 22c is fixedly mounted on the lower side fence moving shaft 22, and the tray paper width detection sensor 8 is provided.
6a to 86d are mounted on the sensor bracket 22c. Paper width detection sensors 86a to 86d for each tray
Is a known light-shielding type optical sensor having a light emitting portion and a light receiving portion.

At the lower part of the side fence 20b, a light shielding plate 201 serving as a sensor operating member for performing a light shielding operation between the light emitting portion and the light receiving portion of each of the tray paper width detection sensors 86a to 86d is fixedly installed. . Side fence vs 20
The light shielding plate 20 is interlocked with the movement of the a and 20b in the paper width direction Y.
When the light shielding plate 20l shields the light between the light emitting unit and the light receiving unit, the tray paper width detection sensors 86a to 86d that are shielded from the light output an ON signal, and the other signals are OFF signals. Is output.

With this configuration, the tray paper width detection sensors 86a to 86d and the light shielding plate 20l are moved up and down in the direction Z.
The positional relationship of does not change even if the pair of side fences 20a and 20b is moved in the paper width direction Y. Further, since the tray paper width detection sensors 86a to 86d are not arranged directly on the paper feed tray 7, even if the paper feed tray 7 moves up and down with respect to the pair of side fences 20a and 20b, it has nothing to do with this.
The sheet size can be detected according to the positions of the pair of side fences 20a and 20b.

The tray paper length detection sensor 87 is arranged on the upper surface of the paper feed tray 7 at a position closer to the rear of each of the tray cutouts 7a and 7b. This can detect only the width of the paper 6 even if the paper size is detected with the above-mentioned configuration. For example, in A4 landscape and A3 portrait, the distance (paper width) between the side fence pairs 20a and 20b is Since they are the same and these differences cannot be distinguished, they are arranged to distinguish them. The tray paper length detection sensor 87 is a well-known reflective optical sensor having a light emitting portion and a light receiving portion, and emits light from the light emitting portion so that when the paper 6 is on the paper feeding tray 7, the white An ON signal is output by detecting the reflected light at the light receiving unit, and the presence or absence of the paper 6 on the paper feed tray 7 is detected. The arrangement position of the tray paper length detection sensor 87 is set on the paper feed tray 7 on the rear side of the rear end of the paper 6 when setting the A4 portrait paper and on the front side of the rear end when setting the B4 portrait paper. For example, each tray paper width detection sensor 8
Depending on the combination of the output signals of 6a to 86d, A4 horizontal and A4
It is possible to distinguish between 3 portraits, B5 landscapes and B4 portraits.

The tray paper presence / absence detection sensor 88 is a reflection type optical sensor arranged at the center of the front end of the paper feed tray 7 in the paper conveyance direction X, and operates similarly to the tray paper length detection sensor 87. Paper 6 on the paper feed tray 7
The presence or absence of is detected.

The cassette sheet presence / absence detecting sensor 90 as the cassette sheet presence / absence detecting means is arranged substantially in the center of the lower surface of the side plate stay 18h above the movable frame 18.
The cassette paper presence / absence detection sensor 90 is a reflection type optical sensor, and detects the presence / absence of the paper 6 ′ in the paper feed cassette 39 set below the cassette paper presence / absence detection sensor 90.

The cassette presence / absence detection sensor 91 as the cassette presence / absence detection means is fixed to the side plate 18b as shown in FIGS. 2, 6, and 13, and is, for example, a microswitch. Paper feed cassette 39 is cassette guide 48
When set to the cassette mounting position by being guided by a and 48b, the front outer wall of the paper storage case 39b of the paper feed cassette 39 pushes the actuator of the cassette presence detection sensor 91 to turn on the cassette presence detection sensor 91, The presence or absence of the paper feed cassette 39 is detected.

As described above, the cover open / close detection sensor 92 is attached to the position shown in FIG. 22 and is composed of, for example, a micro switch.

The cassette paper size detection sensor group 89 includes
As shown in FIG. 23, five cassette paper size detection sensors 89a, 89b, 89c, 89d, 89e (hereinafter,
Simply "cassette paper size detection sensors 89a-89e"
It may be abbreviated as)). It has a function of detecting the paper size of the paper 6 ′ stored in the paper feed cassette 39. Paper size detection sensor for each cassette 89
Reference numerals a to 89e are known light-shielding type optical sensors having a light emitting portion and a light receiving portion.

In FIG. 16, reference numeral 60 indicates a control means. The control means 60 includes I / O (input / output) ports 64, C.
PU (central processing unit) 63, ROM (read-only storage device) 61, RAM (readable and writable storage device) 6
2 and a timer 65 and the like, which are composed of a microcomputer having a configuration in which they are connected by a signal bus. The control means 60 is provided on a control board (not shown) arranged at a predetermined position of the main body frame 1F of the stencil printing machine 1, and is electrically connected to the printing apparatus control means (not shown) for the sake of simplifying the drawing. It is connected. The printing device control means is provided on the control board,
It controls the entire operation of the stencil printing apparatus 1 including the printing operation, and is composed of a microcomputer similar to the control means 60. The printing device control means and control means 60
Is based on ON / OFF signals of a plate making start key and a print start key (both not shown) provided on an operation panel (not shown) provided above the stencil printing apparatus 1 To control.

Upper limit detection sensor 3, middle detection sensor 4, lower limit detection sensor 5, paper surface detection sensor 95, left and right position left limit detection sensor 84, left and right position right limit detection sensor 85, tray paper width detection sensor group 86, tray paper length Detection sensor 8
7, tray paper presence / absence detection sensor 88, cassette paper size detection sensor group 89, cassette presence / absence detection sensor 91, cover open / close detection sensor 92, left / right movement key (left) 82, left / right movement key (right) 81, and tray lowering key 67. , Is electrically connected to the control means 60.

Upper limit detection sensor 3, middle detection sensor 4, lower limit detection sensor 5, paper surface detection sensor 95, left and right position left limit detection sensor 84, left and right position right limit detection sensor 85, tray paper width detection sensor group 86, tray paper length Detection sensor 8
7, tray paper presence / absence detection sensor 88, cassette paper size detection sensor group 89, cassette presence / absence detection sensor 91, cover open / close detection sensor 92, left / right movement key (left) 82, left / right movement key (right) 81, and tray lowering key 67 The ON / OFF signal and the data signal are transmitted to the input port of the control means 60. Each command signal of the control means 60 is output via the output port to the tray elevating / lowering motor drive circuit 71 of the tray elevating / lowering drive device 10, the cassette tray elevating / lowering motor drive circuit 72 of the cassette tray elevating / lowering drive device 40, and the left / right movement drive device 70. It is transmitted to the moving motor drive circuit 73 and the descending key pressing portion illumination drive circuit 93 as needed.

The control means 60 includes an upper limit detection sensor 3, an intermediate detection sensor 4, a lower limit detection sensor 5, and a paper surface detection sensor 9.
5, left / right position left limit detection sensor 84, left / right position right limit detection sensor 85, tray paper width detection sensor group 86, tray paper length detection sensor 87, tray paper presence / absence detection sensor 88,
Cassette paper size detection sensor group 89, cassette presence / absence detection sensor 91, cover open / close detection sensor 92, left / right movement key (left) 82, left / right movement key (right) 81, tray lowering key 67, and tray raising / lowering motor of the tray raising / lowering drive device 10. A command signal and / or an ON signal is sent between the drive circuit 71, the cassette tray elevating motor drive circuit 72 of the cassette tray elevating drive device 40, the left and right moving motor drive circuit 73 of the left and right moving drive device 70, and the descent key pressing portion illumination drive circuit 93. /
The paper feed device 10 is transmitting and receiving the OFF signal and the data signal.
It controls the system of the whole operation such as 0 start, stop and timing.

Timing for starting normal rotation (clockwise rotation) of the tray lifting motor 11, that is, the paper feed tray 7
The rising start timing is set by the control means 60 when the print start key or the plate making start key is pressed. Further, the reverse rotation (counterclockwise rotation) drive start timing of the tray lift motor 11, that is, the descent start timing of the paper feed tray 7 is controlled by the control means 60.
Is set when the tray lowering key 67 is pressed.

The forward (counterclockwise) drive start timing of the cassette tray lift motor 46 in the cassette tray lift drive device 40, that is, the sheet stacking plate 41.
The rising start timing is set by the control means 60 when the plate making start key or the print start key is pressed, or when the paper feed cassette 39 is mounted and the cover 19 is closed.

The control unit 60 controls the right / left movement key (left) for the forward / reverse rotation drive start timing of the left / right movement motor 32 in the left / right movement drive device 70, that is, the left / right movement start timing of the movable frame 18.
It is set when 82 or the horizontal movement key (right) 81 is pressed, and the horizontal movement motor drive circuit 73 issues a command to the horizontal movement motor 32.

The CPU 63 uses the cassette presence / absence detection sensor 9
When 1 detects the mounting of the paper feed cassette 39, the cassette tray elevating drive device 40 is operated to raise the sheet stacking plate 41, the tray elevating drive device 10 is prohibited from driving, and the cassette presence / absence detection sensor 91. Paper feed cassette 39
When the mounting of the tray is not detected, the tray lifting drive device 10
It has the function of raising the paper feed tray 7 (see claim 1).

The CPU 63 uses the cassette presence / absence detection sensor 9
When the mounting of the paper feed cassette 39 is detected by 1 and the lower limit position P3 of the paper feed tray 7 is detected by the lower limit detection sensor 5, the cassette tray lifting drive device 40 is operated to raise the paper stacking plate 41. At the same time, the tray elevating and lowering drive device 10 is prohibited from being driven. On the other hand, when the paper feed cassette 39 is not detected by the cassette presence / absence detection sensor 91, the tray elevating and lowering drive device 10 is operated to move the paper feed tray 7 for a predetermined time. After raising, and when the lower limit detection sensor 5 does not detect the lower limit position P3 of the paper feed tray 7, the tray elevating drive device 10 is operated to elevate the paper feeding tray 7, and the tray elevating drive device 10 is operated. After elevating the paper feed tray 7 for a predetermined time, and when the lower limit detection sensor 5 detects the lower limit position P3 of the paper feed tray 7, the tray elevating drive device is installed. It has a function of stopping the increase of the paper feed tray 7 and 10 (see claim 2).

In the CPU 63, the side fence frame lower limit detection sensor 83 detects the frame lower limit position of the frame 28, and the cassette paper presence / absence detection sensor 90 detects the paper feed cassette 3.
When the sheet 6'in the sheet 9 is detected, the cassette tray elevating drive device 40 is operated to raise the sheet stacking plate 41 so that the sheet 6'on the sheet stacking plate 41 can be fed at the sheet feeding position. At the same time, the drive of the tray elevating and lowering drive device 10 is prohibited, the side fence frame lower limit detection sensor 83 detects the frame lower limit position of the frame 28, and the cassette paper presence / absence detection sensor 90 detects the paper 6 ′ in the paper feed cassette 39. Is not detected,
The tray elevating and lowering drive device 10 is used to permit the elevating and lowering of the paper feed tray 7, and the tray elevating and lowering drive device 10 is used to elevate and lower the paper feed tray 7 for a fixed time or a fixed amount. When the side fence frame lower limit detection sensor 83 does not change the detection state of the frame lower limit position of the frame 28 from the detection state to the non-detection state even after driving, the tray elevating and lowering drive device 10 is used to perform the sheet feeding tray. 7 has a function of stopping (see claim 3).

The CPU 63 uses the cassette presence / absence detection sensor 9
When the mounting of the paper feed cassette 39 is detected by 1 and the closed state of the cover 19 is detected by the cover open / close detection sensor 92, the cassette tray elevating drive device 4
It has a function of raising the sheet stacking plate 41 by 0 and making it possible to feed the sheet 6 ′ on the sheet stacking plate 41 at the sheet feeding position (see claim 4).

The CPU 63 uses the cassette presence / absence detection sensor 9
When the mounting of the paper feed cassette 39 is detected by 1 and the open state of the cover 19 is detected by the cover open / close detection sensor 92, the cassette tray lifting drive device 4
It has a function of lowering the paper stacking plate 41 by 0 (see claim 5).

The CPU 63 has a function of driving the cassette tray elevating / lowering device 40 to lower the sheet stacking plate 41 at least until the sheet stacking plate 41 reaches the cassette lower limit position Pc (see claim 6).

When the CPU 63 drives the cassette tray elevating / lowering device 40 to lower the sheet stacking plate 41,
At least the paper stacking plate 41 has a function of lowering the paper stacking plate 41 by using the cassette tray elevating and lowering drive device 40 for a fixed time longer than the time required to reach the cassette lower limit position Pc from the upper limit position P1. 7).

When the apparatus power is turned on, the CPU 63
If the cassette presence / absence detection sensor 91 does not detect the mounting of the paper feed cassette 39, the tray elevating / lowering drive device 10 is operated based on the signal from the paper surface detection sensor 95 to move to the paper surface detection position P4 corresponding to the paper surface height position. It has a function of stopping the paper feed tray 7 (see claim 9).

In addition to the above-mentioned characteristic control functions of the present invention, noteworthy functions other than the above-mentioned functions will be listed.
Further, the CPU 63 sets the function of stopping the paper feed tray 7 at the intermediate position P2 based on the ON signal from the intermediate detection sensor 4 and the tray lowering key 67 for a predetermined time (3 seconds in this embodiment). By operating as described above, the tray elevating motor 11 of the tray elevating drive device 10 is operated based on the ON signal from the lower limit detection sensor 5 without taking in the ON signal from the intermediate detection sensor 4 to move the paper feed tray 7 to the lower limit position. It has the function of stopping at P3.

Further, in the case of feeding the paper 6 onto the paper feed tray 7, the CPU 63 at least in the standby state after the power supply of the apparatus is turned on, based on the ON signal from the paper surface detection sensor 95, the tray lifting drive device. 10 to stop the paper feed tray 7 at the paper surface detection position P4.

Further, the CPU 63 turns on the lamp 94 as an illuminating device only when the paper feed tray 7 can be lowered, and operates the tray lifting drive device 10 only when the lamp 94 is turned on. It has a function of allowing the paper tray 7 to be lowered.

Further, the CPU 63 uses the program data stored in the ROM 61 and the tray paper width detection sensor 86.
a-86d and the tray paper length detection sensor 87, the paper size and orientation are calculated based on the ON / OFF signals, and various controls of the stencil printing apparatus 1, for example, stencil printing for setting the stencil writing area, etc. A command signal is transmitted to each part of the device 1. The tray paper width detection sensors 86a to 8 described above
Table 1 shows an example calculated by the CPU 63 based on the respective output signals of 6d and the tray paper length detection sensor 87. In Table 1, when the paper size signals of the tray paper width detection sensors 86a to 86d and the tray paper length detection sensor 87 are ON, a circle is indicated, when the paper size signal is OFF, a − is indicated, and a paper size column is also shown. The asterisk mark (*) indicates an intermediate size set between the standard sizes and an irregular size.
According to this example, the tray paper width detection sensor 86 described above is used.
The combination of a to 86d and the tray paper length detection sensor 87 has an advantage that the paper size and the paper loading direction can be detected.

[0114]

[Table 1]

In the CPU 63, the program data stored in the ROM 61 and the cassette size detection sensor actuator 125K ₁ or 125K ₂ shield the light emitting / receiving elements of the cassette paper size detection sensors 89a to 89e. The paper size and orientation are calculated based on the ON / OFF signal generated by the operation, and a command signal is transmitted to each part of the stencil printing machine 1 for various controls of the stencil printing machine 1, for example, setting of the plate-making writing area. Table 2 shows an example calculated by the CPU 63 based on the output signals of the cassette paper size detection sensors 89a to 89e described above. In Table 2, the paper size signals of the cassette paper size detection sensors 89a to 89e are indicated by a circle, and the paper size signal is indicated by a minus.

[0116]

[Table 2]

The timer 65 is a time for which the tray lowering key 67 is pressed down through the input port of the control means 60.
The cassette tray elevating and lowering drive device 40 is driven to measure the descending time of the sheet stacking plate 41 or the jam detection time,
Output to the CPU 63 at any time. The timer 65 also has a function of measuring the time from the start of rotation of the paper feed roller 2 in order to detect the presence or absence of a jam near the paper feed roller 2.

The ROM 61 stores the start-up of the paper feeding device 100,
Programs and necessary data relating to operations such as stop and timing are stored in advance. RAM 62 is a CPU
The calculation result at 63 is temporarily stored, and ON / OFF signals and data signals input from the sensors and keys are stored at any time.

Next, the operation will be described. A well-known operation of the stencil printing apparatus 1, that is, a plate discharge operation, a document image reading operation, and a plate making / plate supplying operation are performed at the same time as the test printing is performed. The stencil printing process is completed by repeating the processes of paper, printing, and paper ejection for the number of printed sheets.

The paper feed process is started by pressing the plate making start key or the print start key, and a paper feed command signal is transmitted from the control means 60 to the paper feed device 100 of the paper feed section 58. When the paper feed command signal is transmitted from the control means 60, the tray elevating motor 11 is driven in the normal direction to raise the paper feed tray 7. When the paper feed tray 7 rises and the upper limit detection sensor 3 detects the uppermost surface of the paper 6 stacked on the paper feed tray 7 facing the proper paper feed position, the controller 60 causes the tray lifting motor 11 to move. To the tray lifting motor 11 by transmitting a drive stop signal to
The normal rotation driving of the paper is stopped, the uppermost surface of the paper 6 in the paper feed tray 7 is held at the upper limit position P1, and the paper feed roller 2 continues.
A known paper feeding operation is started.

Next, the operation contents of the descending key pressing portion illumination drive circuit 93 will be described. Down key pressing unit illumination drive circuit 93
This operation is performed by sending the following command signal from the CPU 63 via the output port to the descending key pressing portion illumination drive circuit 93. The CPU 63 determines the state of the sheet feeding device 100 based on the output signals of the various sensors and the program called from the ROM 61, and the sheet feeding tray 7
Only when it is in a state where it can be lowered, a command signal is transmitted to the descending key pressing portion illumination drive circuit 93 to turn on the lamp 94,
When the paper feed tray 7 cannot be lowered, the lamp 9
The lighting operation of the lamp 94 is controlled so that the lamp 4 is not lit.

As an example of the operation, as a condition that the paper feed tray 7 cannot be lowered and the lamp 94 is not turned on,
This is a case where the lower limit detection sensor 5 is on and the paper feed tray 7 is located at the lower limit position P3. In this case, it is not necessary to lower the paper feed tray 7 below the lower limit position P3.
0 may be overloaded and its descent must be prohibited. Under other conditions, the lamp 94 is turned on because it is necessary to lower the paper feed tray 7 for replenishment of the paper 6, jam processing, or mounting of the paper feed cassette 39.

When the lamp 94 is not lit, the CPU 63 does not output a command for lowering the paper feed tray 7 to the tray elevating motor drive circuit 71 even if a pressing signal for the tray lowering key 67 is input (the pressing signal is taken in). No)
The tray lifting motor 11 is controlled so as not to be driven to rotate. On the other hand, when the lamp 94 is lit, the tray elevating motor 1 is operated based on the depression signal of the tray lowering key 67.
1 is controlled to rotate.

As described above, when the paper feed tray 7 cannot be lowered, the lamp 94 inside the tray lowering key 67 push-down portion is turned off.
If you write down a notice saying "The tray down key works effectively only when the pressed part of the tray down key is lit" and make it known, the user may have an abnormality in the device due to mechanical conditions. You can't get it wrong.

In this embodiment, the condition for prohibiting the lowering of the paper feed tray 7 is only when the lower limit detection sensor 5 is on and the paper feed tray 7 is located at the lower limit position P3.
The lowering of the paper feed tray 7 is prohibited and the lamp 94 is turned off also under other conditions such as malfunction prevention and protection of the device itself, conditions that impair the operation of the paper feed cassette 39 side, conditions for preventing malfunction of the user, and the like. You may do it. Further, in the present embodiment, during the lowering operation of the paper feed tray 7, the lamp 94 blinks to notify the user that the paper feed tray 7 is moving down, and the apparatus is operating normally. In addition, the user is informed that the paper feed tray 7 is in the descending operation, and the new depression of the tray descending key 67 is invalid, thereby improving the operability.

FIG. 29 is a flowchart showing an example of control operation according to the invention of claim 1. This control operation example represents a case where the lower limit detection sensor 5 does not control. That is, when the cassette presence / absence detection sensor 91 detects the mounting of the paper feed cassette 39, the cassette tray elevating / lowering drive device 40 is operated to raise the sheet stacking plate 41 and the drive of the tray elevating / lowering drive device 10 is prohibited. . On the other hand, when the cassette presence / absence detection sensor 91 does not detect the mounting of the paper feed cassette 39, the tray elevating / lowering drive device 10 is operated to raise the paper feed tray 7.

30 and 31, another control operation example according to the invention of claim 1 is shown in a flow chart.
This control operation example represents a case where the lower limit detection sensor 5 also controls. That is, the cassette presence / absence detection sensor 9
When the mounting of the paper feed cassette 39 is detected by 1 and the lower limit position P3 of the paper feed tray 7 is detected by the lower limit detection sensor 5, the cassette tray lifting drive device 40 is operated to raise the paper stacking plate 41. At the same time, the tray lifting drive device 10 is prohibited from being driven. On the other hand, when the paper feed cassette 39 is not detected by the cassette presence / absence detection sensor 91, the tray elevating / lowering drive device 10 is operated to raise the paper feed tray 7 for a predetermined time, and then the lower limit detection sensor 5 supplies the paper. When the lower limit position P3 of the paper tray 7 is not detected, the tray elevating drive device 10 is operated to raise the paper feed tray 7. Further, after the tray elevating drive device 10 is operated and the paper feed tray 7 is raised for a predetermined time, and after the tray elevating drive device 10 is operated and the paper feed tray 7 is raised for a predetermined time. When the upper limit detection sensor 3 detects the upper limit position P1 of the paper feed tray 7, the tray elevating and lowering drive device 10 is operated to stop the raising of the paper feed tray 7.

32 and 33, another control operation example according to the invention of claim 3 is shown in a flow chart.
The control operation will be described with reference to FIGS. 4, 6, 25 and 26. To stop the lowering operation of the paper feed tray 7, see FIG.
As shown in, the side fence frame lower limit detection sensor 83 starts to turn off and then stops when the connecting member 111a descends by the descending distance l. The descent distance 1 is set by stopping the tray elevating motor 11 after a certain time has elapsed after the side fence frame lower limit detection sensor 83 is turned off by the timer 65, or as shown by the phantom line in FIG.
The encoder 11a attached to the rotary shaft of No. 1 and having a large number of slits in the vicinity of the outer periphery, and the transmission type optical sensor 11b fixed to the side plate 18a so as to detect the slit portion of the encoder 11a are used to rotate the tray lifting motor 11. By the pulse generator that outputs the pulse, the rotation angle of the tray lifting motor 11 after the side fence frame lower limit detection sensor 83 is turned off is controlled.

As shown in FIG. 6, the descent distance l is set when the side fence pair 20a, 20b is located at the lower limit position Pb as the lower fixed position, and the side fence pair 20a, 20b
It is larger than the gap l1 between the uppermost surface of 20b and the bottom wall surface of the paper storage case 39b of the paper feed cassette 39 at that position,
And the lower surface of the side fence moving axis 21 (up to here,
It is set to be smaller than the gap l2 between the paper 6 that can be stacked on the paper feed tray 7 at the maximum) and the lowermost position of the bottom wall surface of the paper storage case 39b (that is, l2>l>).
The dimensions of each component are set to be 11). When the paper cassette 39 is not installed,
As the paper feed tray 7 moves up, the frame 28 moves to the upper limit position P1.
However, when the paper feed cassette 39 is installed, even if the paper feed tray 7 moves up, the side fence pair 2
0a and 20b can rise only 11 and stop at this position, and the rise of the sensor detection piece 111d also stops. On the other hand, the tray elevating motor 11 further rotates to raise the paper feed tray 7 by the descending distance l. When the detection piece 111d does not operate the side fence frame lower limit detection sensor 83 from off to on, the rotation of the tray elevating motor 11 is stopped. At this time, l2>
Since it is l, the paper on the paper feed tray 7 does not rise to the lowermost surface of the paper feed cassette 39, and the interference between the paper 6 and the paper feed cassette 39 can be prevented.

As shown in FIGS. 4 and 6, when the print start key is pressed, the cassette sheet presence / absence detecting sensor 90 detects the sheet 6'in the sheet feeding cassette 39, and outputs an ON signal to output the side fence. Frame body lower limit detection sensor 8
When 3 is outputting an OFF signal, that is, when the sensor detection piece 111d provided on the connecting member 111a shields the side fence frame lower limit detection sensor 83 from light, the paper feed cassette 39 is mounted. Therefore, the rotation driving of the tray lifting motor 11 of the tray lifting driving device 10 is stopped, the cassette tray lifting motor 46 of the cassette tray lifting driving device 40 is driven to rotate, and the paper feeding cassette 39
The inner sheet 6'is raised to the sheet feeding position. When the side fence frame lower limit detection sensor 83 is in the off signal output state and the cassette presence / absence detection sensor 91 is also in the off signal output state, it means that the paper feed cassette 39 is not installed and the paper feed tray 7 occupies the lower limit position P3. The rotation drive of the cassette tray lifting motor 46 is stopped, and the tray lifting motor 11 is stopped.
Are driven to rotate so that the sheet feeding tray 7 faces the sheet feeding position.
However, the cassette paper presence / absence detection sensor 90 does not print when the paper feed cassette 39 is mounted and the already printed paper 6 ′ such as two-color printing is used as the paper 6 ′ in the paper feed cassette 39. When the completed solid portion is at the detection position of the cassette sheet presence / absence detection sensor 90, the cassette sheet presence / absence detection sensor 90 outputs an off signal. When the sheet feed tray 7 is raised to the sheet feed position, the sheets 6 stacked on the sheet feed tray 7 interfere with the sheet feed cassette 39, and as described above, the sheet feed tray 7 is raised by 1 minute. When the side fence frame lower limit detection sensor 83 does not detect ON even if the tray elevating motor 11 is driven to rotate, the paper feed cassette 39 is mounted on the side fence pair 20a, 20b.
Since it is determined that a and 20b cannot rise by 11 or more, the rotation drive of the tray elevating motor 11 that raises the paper feed tray 7 is stopped at this point to prevent the above interference. In the subsequent operation, the paper feed tray 7 is lowered until the lower limit position P3 is detected by the lower limit detection sensor 5, and then the cassette tray elevating motor 46 is rotationally driven to remove the paper 6 ′ in the paper feed cassette 39. Raise to the paper feeding position.

FIG. 34 is a flow chart showing an example of the control operation according to the invention of claim 4. The control means 60 of this control operation example, when the cassette presence / absence detection sensor 91 detects the mounting of the paper feed cassette 39 and the cover opening / closing detection sensor 92 detects the closed state of the cover 19, the cassette tray The elevating drive device 40 is used to raise the sheet stacking plate 41 so that the sheet 6 ′ on the sheet stacking plate 41 can be fed at the sheet feeding position. That is, the paper feed cassette 39 is mounted and the cassette presence / absence detection sensor 91
Is turned on, and then the cover 19 is closed and the cover opening / closing detection sensor 92 is turned on, the cassette tray lifting motor 46 is immediately driven to rotate, and the uppermost sheet 6 ′ on the sheet stacking plate 41 is fed. The motor 46 is rotationally driven until the position is reached.

FIG. 35 is a flow chart showing an example of control operation according to the present invention. The control means 60 of this control operation example, when the cassette presence / absence detection sensor 91 detects the mounting of the paper feed cassette 39 and the cover opening / closing detection sensor 92 detects the open state of the cover 19, the cassette tray The elevating drive device 40 is used to lower the sheet stacking plate 41. Then, the cassette tray elevating drive device 40 is driven to lower the sheet stacking plate 41 so that at least the sheet stacking plate 41 moves to the cassette lower limit position P.
Let it reach c. That is, when the CPU 63 drives the cassette tray elevating and lowering device 40 to lower the sheet stacking plate 41, the CPU 63 requires at least the time required for the sheet stacking plate 41 to reach the cassette lower limit position Pc from the upper limit position P1. The cassette tray elevating and lowering drive device 40 is operated and the sheet stacking plate 41 is lowered for a long fixed time.

For example, when the paper feed cassette 39 is mounted and the cassette presence / absence detection sensor 91 is in the ON state,
As soon as the cover 19 is opened and the cover opening / closing detection sensor 92 is turned off, the cassette tray elevating motor 46 is rotationally driven, and the sheet stacking plate 41 starts to descend. As shown in FIG. 8, the lowering operation of the sheet stacking plate 41 is performed by the stacking plate raising / lowering arm 42 in the arm storage recess 3 in the sheet feeding cassette 39.
It is performed until it reaches the lowest position where it abuts the inner bottom wall of 9a. At this time, the sheet stacking plate 41 can be lowered only up to the stopper 39c in the sheet feeding cassette 39, and the sheet 6'and the sheet stacking plate 4 are mounted on the stacking plate elevating arm 42.
1 is not applied, and the load is not applied to the arm shaft gear 44 of the stacking plate elevating arm 42 and the elevating arm drive gear 45 of the cassette tray elevating motor 46. It is possible to easily and easily remove the paper feed cassette 39 without applying an extra load to release the engagement between the paper feed cassette 39 and the gear 45.

Here, the above control operation will be supplementarily described with reference to FIGS. When lowering the sheet stacking plate 41, the arm shaft gear 44 is rotated in the counterclockwise direction, and the stacking plate elevating arm 42 also tries to rotate in the same counterclockwise direction, but the one-way clutch 44a is loose. Therefore, the gear plate 44 cannot directly rotate the stacking plate elevating arm 42 in the counterclockwise direction. However, the stacking plate elevating arm 42 includes the stacking plate 4
Since the load of 1 and the sheets 6 ′ stacked thereon is applied, the stacking plate elevating arm 42 is rotated in the counterclockwise direction so that the one-way clutch 44a is in the closing direction. As shown in FIG. 8, if the gear 44 is rotated in the counterclockwise direction even when the loading plate elevating arm 42 reaches the lowermost position in the paper feeding cassette 39, as shown in FIG. Since the loosening rotation is performed, the cassette tray lifting motor 46 does not lock.

Therefore, the cassette tray lifting motor 4
The rotation angle of 6 may be controlled as follows. The stacking plate elevating arm is an angle larger than the angle from the position of the stacking plate elevating arm 42 when the sheet stacking plate 41 contacts the sheet feeding roller 2 and reaches the sheet feeding position to the stacking plate elevating arm 42 at the lowest position. When the rotation angle of the gear 45 of the cassette tray lifting motor 46 is set so that the motor 42 is moved, and the time required to rotationally drive this rotation angle is T1, the cassette tray lifting motor 46 always moves at T1 during the lowering operation. The rotation is performed for the above time. By controlling the cassette tray elevating motor 46 in this way, the stacking plate elevating arm 42 can descend to the lowest position even when the sheet stacking plate 41 occupies the uppermost position, that is, the upper limit position P1. The paper stacking plate 41 is at the upper limit position P.
Even when it does not occupy 1, after the stacking plate lifting arm 42 reaches the lowest position, the gear 44 loosens and rotates in the rotation direction, and no load is applied to the cassette tray lifting motor 46. Therefore, a detection mechanism for detecting the position of the stacking plate elevating arm 42 is unnecessary, and the CPU 6 of the control means 60 is mainly used.
It is possible to control the rotation angle of the cassette tray raising / lowering motor 46 by the control configuration of only 3 and the timer 65, which is advantageous in that the cost is low and the cassette tray raising / lowering motor 46 is not damaged due to an excessive load. is there.

Next, with reference to FIGS. 8, 13, 15, 27 and 28, a configuration example and operation according to the invention of claim 8 will be described. In FIG. 8, the sheet stacking plate 41
Is regulated by a stopper 39c (see also FIG. 13) in the paper storage case 39b of the paper feed cassette 39 as a lower limit at the lowest position. The size and shape of each component are set so that a gap Lc is formed between the upper surface of the stacking plate elevating arm 42 that occupies the lowest position and the lower surface of the paper stacking plate 41 that occupies the lowest position. The stacking plate elevating arm 42 and the sheet stacking plate 41 are stopped at the same position. As described above, the one-way clutch 44a is built in the gear 44 of the stacking plate raising / lowering arm 42, and as shown in FIG. Since 44 is loose and can rotate in the rotation direction, there is no possibility that the gear 44 and the gear 45 are not meshed with each other and are difficult to insert when the paper cassette 39 is inserted / installed.
When removing, that is, when pulling out, the gear 44 is the gear 4
5, the one-way clutch 44a is rotated in the tightening direction.

Therefore, when the sheet stacking plate 41 is placed on the stacking plate elevating arm 42 and a load combined with the sheet 6'on the sheet stacking plate 41 is applied, the stacking plate elevating arm 42 moves in the clockwise direction. It is difficult to rotate, and in order for the gear 44 to rotate in the clockwise direction (tightening direction), it is necessary to overcome the load, and a large force is required to pull out the paper feed cassette 39. However, as described above, if the gap Lc between the upper surface of the stacking plate elevating arm 42 and the lower surface of the sheet stacking plate 41, which occupy the lowest position of each, is secured, the stacking plate arm 42 is Since the above load is not applied to rotate between Lc, a large force is not required, and smooth rotation is possible, and the gear 44 can also rotate with a small force. Three
The pulling force of 9 does not increase.

Here, the required amount of the gap Lc is shown in FIGS.
28 and FIG. 28. In FIG. 8, the angle a
B is the angle at which the stacking plate elevating arm 42 can rotate within the gap Lc. Therefore, the gear 44 needs to be rotatable by the same angle. FIG. 27 shows the meshing state and the disengaged state of the gear 44 and the gear 45. In FIG. 15, the meshing direction of the gears 44 and 45 (the line connecting the centers of the gears) is the same as that of the paper feeding cassette 3.
Although it is a direction substantially orthogonal to the attaching / detaching direction of 9, the angle α representing the engagement direction is actually shown as shown in FIG.
= 110 to 130 °, which is set to a larger angle than a right angle. This is the angle α = 9, as will be described later.
At 0 °, when the paper feed cassette 39 is pulled out, the rotation amount when the gear 44 is disengaged from the gear 45 while meshing so that the gear 44 rolls with respect to the gear 45,
This is because the angle aB shown in FIG. 8 is the largest. Figure 2
In Fig. 7, when the gear 44 is removed in the removal direction in the figure, the range in which the gear 44 rotates while meshing around the gear 45 is from the point a1 where the tip circles of the gears 44 and 45 intersect at the meshing position. It is a range up to a point b1 where the tip circles of 44 and 45 are separated from each other, and is a range of an angle aA on the gear 45. In the range of the angle aA, the gear 44 also rotates, and its rotation angle is the same as the angle aB. When the number of teeth of the gear 44 is Z1 and the number of teeth of the gear 45 is Z2, aB = Z2
/ Z1 × aA. The angle aB does not always take the above value, but becomes the above value at maximum only when the tooth tips of both teeth are in contact with each other at the point a1 at the meshing position of the gears 44 and 45. However, it usually has a smaller value. Therefore, the gap Lc may be set so that the gear 44 and the gear 45 can rotate by the angle aB.

The angle aA becomes smaller as the angle α representing the meshing direction becomes larger, and when the angle α = 180 °,
As a matter of course, when the angle aA = 0 ° and the angle α = 90 °, the range in which the addendum circle of the gear 44 interferes with the addendum circle of the gear 45 at the time of detaching the paper feed cassette 39 becomes the largest, so the angle aA becomes It becomes the maximum and the amount of the angle aB also becomes large. (When the angle α is less than 90 °, the gears 44 and 45 come close to the meshing position when the paper cassette 39 is removed, so that it cannot be removed.) However, if the angle α is large, the paper cassette 39 is inserted and mounted. At times, the teeth of the gear 44 and the gear 45 are likely to interfere with each other, and even if the one-way clutch 44a is built in the gear 44, it cannot be inserted. Therefore, the angle α = 100 to 140 ° is the best. Further, even if the angle α is set to the above range, the angle aA or the angle aB becomes large, and the gap Lc shown in FIG. The amount of sheets 6 ′ that can be stacked in the cassette 39 is reduced. As a method for reducing this, if a method of making the tooth tip portions of the gears 44 and 45 thinner than the standard tooth profile as shown in FIG. 28, the angle aB
Can be made smaller and the gap Lc can be set smaller.

In FIG. 28, the tooth profile from the portion slightly outside the meshing pitch circle portion to the tooth tip is ground to be thinner than the standard tooth profile indicated by the two-dot chain line (the hatched portion is cut), and the tip of the tooth tip is rounded. It has an R shape. This allows
In FIG. 27, the play (backlash) between both gears 44 and 45 becomes large at points a1 and b where the tooth tips of both gears 44 and 45 intersect and slightly inside thereof. Therefore, both gears 4
Even if 4, 45 move relatively, the gear does not rotate until the backlash disappears, so the rotation angle aA of the gear becomes smaller accordingly.

Next, the control contents of the lowering operation of the paper feed tray 7 will be described with reference to the flow charts of FIGS. In this embodiment, the tray lowering key 6 has the above-mentioned configuration.
Since the control means 60 for switching the lower limit position for lowering the paper feed tray 7 is provided according to the length of the pressing time of 7, the paper surface detection position P4 or the intermediate position P2 if the tray lowering key 67 is pressed for less than 3 seconds. It is possible to lower the paper feed tray 7 to the lower limit position P3 if the time for which the tray lowering key 67 is pressed is 3 seconds or more.

FIG. 17 is a flow chart for judging whether the lowering end position of the sheet feeding tray 7 should be the sheet surface detection position P4 or the lower limit position P3, depending on the pressing time of the tray lowering key 67. First, the flow of processing when the tray down key 67 is pressed for 3 seconds or more will be described. When it is determined in step S10 that the tray lowering key 67 has been pressed, the process proceeds to step S11, and it is determined whether or not the pressing time of the tray lowering key 67 is 3 seconds or more. If the pressing time of the tray lowering key 67 is 3 seconds or more, the paper feeding tray 7 is lowered to the lower limit position P3 in step S12.
Then, the "down flag to lower limit position P3" is turned on. Next, in step S14, the "down flag to the sheet surface detection position P4" is turned off.

Next, the pressing time of the tray lowering key 67 is 3
The flow of processing when it is less than seconds is explained. Step S10
When it is determined that the tray lowering key 67 has been pressed,
Proceeding to step S11, it is determined whether or not the pressing time of the tray lowering key 67 is 3 seconds or more. If the pressing time of the tray lowering key 67 is less than 3 seconds, the process proceeds to step S13 to lower the paper feed tray 7 to the paper surface detection position P4, and the "down flag to the paper surface detection position P4" is turned on.

FIG. 18 is a flow chart showing the control of the tray elevating / lowering drive device 10 by the "lowering flag to the lower limit position P3". First, when it is determined in step S15 that the "lowering flag to the lower limit position P3" is turned on,
In step S16, the drive of the tray elevating / lowering drive device 10 is started (the lowering operation of the paper feed tray 7 is started). afterwards,
In step S17, it is determined whether or not the paper feed tray 7 has reached the lower limit position P3, and the tray elevating drive device 10 is driven (the paper feed tray 7 until the paper feed tray 7 reaches the lower limit position P3).
Lowering operation). If it is determined in step S17 that the paper feed tray 7 has reached the lower limit position P3, the process proceeds to step S18 and the "lower flag to lower limit position P3" is set.
Is turned off, and then the process proceeds to step 19, the drive of the tray elevating and lowering drive device 10 is stopped, and the lowering operation of the paper feed tray 7 is completed.

FIG. 19 is a flow chart showing the control of the tray elevating and lowering drive device 10 by the "down flag to the sheet surface detection position P4". First, in step S20, when it is determined that the "down flag to the paper surface detection position P4" is turned on, the process proceeds to step S21, and the tray lifting drive device 1
The driving of 0 starts and the paper feed tray 7 is lowered. Then, in step S22, it is determined whether or not the paper surface detection sensor 95 is turned on. In the following steps, there is a flow of stopping the lowering operation of the paper feed tray 7 by operating the tray lift drive device 10 when the paper surface detection sensor 95 is off.
Since there is a small amount of paper 6 on the top and the paper feed tray 7 itself may be located above the paper surface detection sensor 95, in this case, the lowering of the paper feed tray 7 is immediately stopped. Therefore, in order to prevent such a stop of the paper feed tray 7, in step S22, the side edge of the upper portion of the paper 6 on the paper feed tray 7 (hereinafter, simply referred to as “stacked paper upper surface”) is once. The purpose is to lower the paper until it is detected by the paper surface detection sensor 95.

When it is determined in step S22 that the paper surface detection sensor 95 is turned on, the paper feed tray 7 is further lowered, and the process proceeds to step S23. In step S23, it is determined whether the intermediate detection sensor 4 is on. If the intermediate detection sensor 4 is not on, the process proceeds to step S26.
In step S26, it is determined whether or not the paper surface detection sensor 95 is turned off, and when it is not turned off, step S23
Return to. If the paper surface detection sensor 95 is turned off, that is, if the upper surface of the stacked sheets on the paper feed tray 7 is located below the paper surface detection sensor 95, the process proceeds to step 27.
The "lowering flag to the sheet surface detection position P4" is turned off, and then the process proceeds to step 28, the drive of the tray elevating / lowering drive device 10 is stopped, the lowering operation of the sheet feeding tray 7 is stopped, and the stacked sheets on the sheet feeding tray 7 are stopped. The paper feed tray 7 is stopped when the upper surface is slightly lower than the position of the paper surface detection sensor 95.

When it is determined in step S23 that the intermediate detection sensor 4 is turned on, that is, the upper surface of the stacked sheets on the paper feed tray 7 is not lowered to the position of the sheet surface detection sensor 95, the intermediate detection sensor 4 is turned on. If so, the process proceeds to step S24, and "fall flag to paper surface detection position P4"
Is turned off, and the tray elevating / lowering drive device 10 is operated in step S25.
Is stopped, and the paper feed tray 7 stops at the intermediate position P2.

In this way, when the amount of stacked sheets on the sheet feeding tray 7 is relatively small, the sheet feeding tray 7 stops at the sheet surface detection position P4, and even when the amount of stacked sheets on the sheet feeding tray 7 is large. The paper feed tray 7 stops at the intermediate position P2. In steps S26 to S28, the paper feed tray 7 detects the paper surface detection position P4.
If stopped at, the sheets 6 can be replenished on the stacked sheets in the sheet feed tray 7. Then, after the paper 6 is replenished, if the tray lowering key 67 is pressed again for less than 3 seconds, the paper feeding tray 7 moves down to the paper surface detection position P4 again. The paper 6 can be replenished one after another. At this time, as for the amount of replenishable paper 6, the distance (distance) between the upper surface of the stacked paper on the paper feed tray 7 and the paper feed roller 2 at the paper surface detection position P4 is about 100 mm, and if the quality paper is 55 kg. Since 1000 sheets of paper 6 for one pack can be replenished, there is an advantage that the paper 6 can be replenished for one pack each time the tray lowering key 67 is pressed. If the paper feed tray 7 is lowered to the intermediate position P2 while performing such a paper 6 replenishment operation, the paper feed tray 7 will not be lowered any further, so that the paper is loaded on the paper feed tray 7 at the intermediate position P2. Since it becomes impossible to replenish more than the amount of paper 6 corresponding to the distance (distance) between the upper surface of the paper and the paper feed roller 2, the paper 6 may be overloaded on the paper loaded in the paper feed tray 7. Can be prevented.

When the tray lowering key 67 is pressed for 3 seconds or more and the paper feeding tray 7 is lowered to the lower limit position P3, between the upper surface of the stacked paper on the paper feeding tray 7 and the paper feeding roller 2.
Further, a space for stacking the sheets 6 is created by an amount corresponding to the interval between the upper limit position P1 and the intermediate position P2, but when the paper feed tray 7 descends to the lower limit position P3, the frame 28 is also included. While descending, the side fence moving axis 21 also descends simultaneously with the descending operation of the paper feed tray 7, and when the cover 19 covering the opening 58A opening to the cassette mounting space 39S is opened, the opening 58A is opened. The descending side fence moving axis 21 faces, and this side fence moving axis 21 faces the paper 6 on the paper feeding tray 7.
Since the paper 6 is not replenished on the paper feed tray 7 due to the trouble of the replenishment of the paper, the distance between the upper surface of the stacked paper on the paper feed tray 7 and the lower end of the side fence moving shaft 21 does not change, and both of them do not change. The amount of sheets 6 that can be stacked between the sheets does not change, and it is possible to prevent the sheets 6 from being excessively stacked on the stacked sheets of the paper feed tray 7.

Next, with reference to FIGS. 20 and 21, the initial operation of the paper feed tray 7 when the power of the apparatus is turned on will be described. First, since the position of the paper feed tray 7 is unknown when the power of the device is turned on, the tray elevating drive device 10 is driven to raise the paper feed tray 7 in step S30. Then step S3
1, the upper limit detection sensor 3 turns on, and the paper feed tray 7
When the upper surface of the upper stacked sheets reaches the sheet feeding position, the process proceeds to the tray lowering mode flow of the connector J1.

When the position of the upper surface of the stacked sheets on the sheet feed tray 7 is considerably lower than the upper limit position P1 and the upper limit detection sensor 3 is off, the process proceeds to step S32 and whether the intermediate detection sensor 4 is turned on or not. Is determined. Step S3
2, the position of the paper feed tray 7 at the start of raising is the intermediate position P2.
When the intermediate detection sensor 4 is on the lower side, the process proceeds to step S35 if the intermediate detection sensor 4 is in the ON state. To step S33. When the position of the paper feed tray 7 at the start of raising is between the paper surface detection position P4 and the intermediate position P2, the intermediate detection sensor 4
Is not turned on, and similarly, the process proceeds to step S33. In step S33, it is determined whether or not the paper surface detection sensor 95 is turned on. When the paper surface detection sensor 95 is turned on, the process proceeds to step S36, the "paper surface once flag" is turned on, and paper surface detection is performed once. The fact is stored, and the process proceeds to step S37. In step S37, it is determined whether or not the "intermediate detection once flag" is turned on and the paper surface detection is performed once. Here, in the case of Yes, that is, when the above items are stored, that is, when the position of the paper feed tray 7 at the start of ascending is lower than the intermediate position P2, the paper feed tray 7 moves to the intermediate position P2. Since it is determined that the sheet has passed and then the sheet surface has been detected, it is not necessary to raise the position of the upper surface of the stacked sheets on the sheet feed tray 7 to the upper limit position P1. Therefore, the processing proceeds to the connector J1, and the tray lowering mode is entered.

In step S37, when the "intermediate detection once flag" is off (when the paper feed tray 7 starts from a position between the intermediate position P2 and the intermediate position P4), the process returns to step S31 and the upper limit detection is performed. If the sensor 3 is turned on, the process proceeds to the connector J1. When the upper limit detection sensor 3 is not turned on in step S31, the above-described control operation flow is repeated, and the upper surface of the stacked sheets on the paper feed tray 7 reaches the upper limit position P.
The paper feed tray 7 is raised until the upper limit detection sensor 3 is turned on and the upper limit detection sensor 3 is turned on. If the upper limit detection sensor 3 is turned on, the process goes to J1 to enter the tray lowering mode.

In this way, when the paper surface detection sensor 95 is turned off in step S33 while the "no intermediate detection once flag" is not turned on in step S37, the paper surface detection sensor 95 is turned off in step S33. When the paper feed tray 7 rises after the paper surface detection sensor 95 is turned on and the paper surface detection sensor 95 is located below the paper feed tray 7 after the number of stacked sheets is small, the process proceeds to step S34, where "paper surface detection" is performed. It is determined whether or not the "once flag" is on,
At this time, since the answer is YES, the processing proceeds to the connector J1 and the tray lowering mode is entered.

Note that the position of the paper feed tray 7 at the start of raising is between the intermediate position P2 and the paper surface detection position P4, and until the paper surface detection sensor 95 is turned on, step S3 is performed.
The program flow of 1, S32, S33, S34 → S31 is repeated.

Next, the flow for stopping the paper feed tray 7 by lowering the paper feed tray 7 with the connector J1 will be described. First, in step S40, the paper feed tray 7 starts to descend. Next, in step S41, the paper surface detection sensor 9
It is determined whether or not 5 is turned on. This step S4
1 enters here because of the following reasons. Paper tray 7
As described above, when the upper limit detection sensor 3 descends from the position where the upper limit detection sensor 3 is turned on, the amount of stacked sheets on the paper feed tray 7 is small, and the paper surface detection sensor 95 may be located below the paper feed tray 7. Yes, in this case, the paper surface detection sensor 95 is turned off. However, in the subsequent stage of the flow of the connector J1, in step S43, when the paper surface detection sensor 95 is off, the lowering operation of the paper feed tray 7 is stopped, so that the paper surface detection sensor is once in step S41. 95
This is because the paper feed tray 7 immediately stops descending after the descent is started unless it is confirmed that is turned on.

When the paper surface detection sensor 95 is turned on in step S41, the process proceeds to step S42. Step S42
In step S44, it is determined whether the intermediate detection sensor 4 is (is) turned on, and if the intermediate detection sensor 4 is on.
Then, the driving of the tray elevating and lowering drive device 10 is stopped, and the paper feed tray 7 is stopped at the intermediate position P2 (the maximum stacking position where the stacking amount of the paper 6 on the paper feed tray 7 can be maximized). If the intermediate detection sensor 4 is off, the process proceeds to step S43. If it is determined that the paper surface detection sensor 95 is off, the process proceeds to step S45, the drive of the tray elevating and lowering drive device 10 is stopped, and the paper feed tray 7 is The paper surface detection sensor 95 stops at a position slightly lower than the position where the upper surface of the stacked paper in the paper feed tray 7 (the side edge of the upper portion of the paper 6 on the paper feed tray 7) is detected.

As described above, when the apparatus power is turned on, the paper feed tray 7 moves down to the paper surface detection position P4 and stops. Therefore, if the paper 6 is small before the start of printing, the paper feed tray below the paper feed roller 2 will be described. The paper 6 can be immediately replenished to the upper surface of the stacked paper of No. 7. Even when the paper 6 does not need to be replenished, the upper surface of the stacked paper on the paper feed tray 7 always stops at a position about 100 mm from the paper feed roller 2, so that the paper can be fed even when the amount of the stacked paper is small. Since the paper feed tray 7 is raised about 100 mm at the start, the waiting time before the start of paper feeding does not need to be long. Further, since the amount of sheets stacked on the sheet feed tray 7 is large, the sheet surface detection sensor 95
Even when is not turned off, since the paper feed tray 7 is stopped at the intermediate position P2, an extra load due to stacking the excess paper 6 is not applied to the tray lifting motor 11.

For example, in a state where the position of the paper feed tray 7 is raised from the position shown in FIGS. 1 and 2 until the uppermost paper 6 stacked on the paper feed tray 7 comes into contact with the paper feed roller 2. The following operations are performed when it is desired to lower the paper feed tray 7 in order to remove jams in the vicinity of the paper feed roller 2 and replenish the paper 6 while feeding paper. First, when the tray lowering key 67 is pressed for less than 3 seconds, the tray raising / lowering motor 11 is reversely driven by the control means 60 based on the ON signal of the tray lowering key 67, and the sheet feeding tray 7 is lowered. When the paper feed tray 7 descends and is detected by the paper surface detection sensor 95 at the position where the paper feed tray 7 reaches the paper surface detection position P4, a drive stop signal is transmitted from the control means 60 to the tray lift motor 11. The reverse rotation of the tray elevating motor 11 is stopped, and the paper feed tray 7 is held at the paper surface detection position P4. Therefore, without performing unnecessary lowering operation of the paper feed tray 7, confirmation of a paper jam, removal of jammed paper, or removal of the paper 6 is performed for jam clearance.
Can be replenished. In addition, the paper feed tray 7 in this state is such that the upper surface of the stacked paper on the paper feed tray 7 is
Since it is stopped at the paper surface detection position P4 which is about 100 mm below the paper feed roller 2, the state shown in FIGS. 1 and 2 is reached, and the rising distance of the paper feed tray 7 is about 100 mm short, so the user is relatively The paper feeding operation can be restarted in a short waiting time.

Further, for example, as shown in FIG. 3, the paper feed tray 7 has reached the intermediate position P2, and the uppermost paper 6 stacked on the paper feed tray 7 is in contact with the paper feed roller 2. When a jam occurs in the vicinity of the paper feed roller 2 when the paper is fully loaded, the paper feed tray 7 has already been moved to the intermediate position P2.
Therefore, even if the tray lowering key 67 is pressed, if the pressing time is less than 3 seconds, the paper feeding tray 7 does not descend. In such a case, the tray lowering key 67
Is pressed for 3 seconds or more, and the control means 60 drives the tray elevating motor 11 in the reverse direction based on the ON signal of the tray lowering key 67 to lower the paper feeding tray 7. When the paper feed tray 7 is lowered and the lower limit detection sensor 5 detects the paper feed tray 7 at the lower limit position P3, the controller 60 sends a drive stop signal to the tray lift motor 11 to cause the tray to move. The reverse rotation of the lift motor 11 is stopped, and the paper feed tray 7 is held at the lower limit position P3.
Distance (distance) between the intermediate detection sensor 4 and the lower limit detection sensor 5
Is 100 mm, the space between the paper feed roller 2 and the uppermost surface of the paper 6 stacked on the paper feed tray 7 is secured within the range of 100 mm distance (distance) at the end of the lowering operation of the paper feed tray 7. The space required for removing the jammed paper can be secured, and the workability of the jam handling is improved.

Therefore, when the sheets 6 stacked on the sheet feed tray 7 are in a full state or near a full state and a jam occurs in the vicinity of the sheet feeding roller 2, once the sheet feeding tray 7 is closed as in the conventional case. Paper 6 loaded in the stack
It becomes unnecessary to remove the jam and secure a space necessary for removing jammed paper.

Next, the paper feeding cassette 39 is loaded into the paper feeding device 100.
The operation in the case of mounting on the paper and feeding the paper will be described. For example, with reference to FIG. 3, as illustrated in FIG. 3, the paper feed tray 7 reaches the intermediate position P2, and the paper feed tray 7 is
Between the paper feed roller 2 and the uppermost sheet 6 in the fully loaded state in which the uppermost sheet 6 stacked on the sheet feeding roller 2 is in contact with the sheet feeding roller 2, or in a state close to such a fully loaded state. It is not possible to secure the space required for mounting the paper feed cassette 39. Further, since the paper feed tray 7 has already reached the intermediate position P2, even if the tray lowering key 67 is pressed, if the pressing time is less than 3 seconds, the paper feeding tray 7 does not descend. Therefore, the tray lowering key 67 is pressed for 3 seconds or more until the lower limit detection sensor 5 detects the sheet feeding tray 7 at the position where the lower limit position P3 is reached through the control operation of the control means 60 as described above. The paper feed tray 7 is lowered. At this time, the side fence pair 20a, 20b
The frame 28 and the frame 28 are pushed down by the lower side fence moving shaft 22 against the lower surface of the paper feed tray 7 against the tension spring 114, so that the solid line position shown in FIG. 6 (or the virtual line shown in FIGS. 1 and 2). Line position).

As a result, the side fence pair 20a, 2
0b and the lower surface of the bottom wall of the paper storage case 39b when the paper feed cassette 39 is mounted, a necessary space that does not interfere with each other is formed, and the cassette mounting space 39S is secured. . Since the distance between the intermediate detection sensor 4 and the lower limit detection sensor 5 is 100 mm,
When the lowering operation of the paper feed tray 7 is completed, a space between the paper feed roller 2 and the uppermost surface of the paper 6 is secured within a height (interval distance) of 100 mm or more (see FIG. 6). As described above, the thickness of the sheet feeding cassette 39 is about 50 to 80 mm, and the sheet feeding cassette 39 is provided at the predetermined portion of the sheet feeding device 100.
When the sheet feeding cassette 39 is mounted, a space between the sheet feeding roller 2 and the uppermost surface of the sheet 6'is secured at least 20 to 50 mm at the height (distance) in the ascending / descending direction Z. Therefore, it is necessary to mount the sheet feeding cassette 39. Sufficient space, that is, the cassette mounting space 39S can be sufficiently secured. In this state, when the cover 19 is opened and the paper feed cassette 39 is completely attached to the left in the drawing via the paper feed cassette attaching / detaching mechanism 47, the elevating arm drive gear 45 and the arm shaft gear 44 mesh with each other. Next, the cover 19 is closed.

In this way, when the plate making start key or the print start key is pressed after the paper feed cassette 39 is mounted, a paper feed command signal is transmitted from the control means 60 to the cassette tray lift drive device 40, The cassette tray elevating motor 46 is driven to rotate in the counterclockwise direction, and the stacking plate elevating arm 42 is swung clockwise through the elevating arm drive gear 45 and the arm shaft gear 44, whereby the stacking plate elevating arm is moved. 42, the free end of the sheet stacking plate 41 is lifted in the clockwise direction,
The uppermost sheet 6 ′ occupies the sheet feeding position where the sheet feeding roller 2 abuts, that is, the upper limit position P <b> 1, and the sheet can be fed. Next, the normal rotation drive of the cassette tray elevating motor 46 is stopped, the uppermost sheet 6 ′ stacked on the sheet stacking plate 41 is held at the upper limit position P1, and the well-known sheet feeding operation by the sheet feeding roller 2 is subsequently started. To be done.

Next, the operation when the paper feed cassette 39 is not attached will be described. When using the paper feed tray 7, the cover 19 is opened and the paper feed cassette 39 is pulled out to the right in the figure. Subsequent operations are the same as those in the above-mentioned example, and therefore their explanations are omitted.

The sheet stacking plate 41 and the like are shown in FIG. 7, and the upper limit detection sensor 3 and the separation roller pair 5 are shown in FIG.
Illustrations such as 1a and 51b are omitted in order to simplify the drawing.

36 and 37, flowcharts of control operation examples according to the invention of claim 9 are shown. This control operation example is different from the examples of FIGS. 20 and 21 in that the presence / absence of the paper feed cassette 39 is determined by the cassette presence / absence detection sensor 91 at the beginning of the initial operation of the paper feed tray 7 when the apparatus power is turned on. The description is omitted because it is the same and the other contents are the same. That is, this control operation is
When the control means 60 is in the power-on state of the apparatus and the cassette presence / absence detection sensor 91 does not detect the mounting of the paper feed cassette 39, the tray elevating / lowering drive device 10 is operated based on the signal from the paper surface detection sensor 95. The paper feed tray 7 is stopped at the paper surface detection position P4 corresponding to the paper surface height position.

As described above, according to the paper feeding apparatus 100, the paper feeding cassette 39 and the pair of side fences 20a, 20a, There is no member positioned above 20b other than the side plate 18g, and a cassette for feeding the paper 6'stored in the interrupt type paper feed cassette 39 without providing a special space above the paper feed roller 2. It is possible to selectively switch between the paper feed mode and the tray paper feed mode in which the paper 6 on the paper feed tray 7 is fed.

Further, according to the paper feeding device 100, the paper feeding operation from the paper feeding cassette or the paper feeding tray can be selectively switched by using the paper feeding roller 2 as the same paper feeding means. Therefore, it is not necessary to change the sheet conveying path from the sheet feeding unit to the image forming unit of the image forming apparatus, and the sheet feeding timing is constant. No device or adjustment / control is required. Especially in stencil printers,
Since a slight difference in the paper feed timing has a great influence on the top-bottom deviation, it is possible to improve the print quality. Further, by using the same sheet feeding means, since the sheet conveying path from the sheet feeding means to the image forming unit of the image forming apparatus is the same, without complicating the configuration of the sheet conveying path or making maintenance difficult, It can be installed in a conventional image forming apparatus and can cope with high-speed paper feeding. Therefore, it is possible to provide a sheet feeding device for an image forming apparatus that is extremely convenient.

The upper limit detection sensor 3 is not limited to the above-mentioned one, but may be a reflection type optical sensor, and the intermediate detection sensor 4 and the lower limit detection sensor 5 are not limited to the above-mentioned ones, and may be one of the paper feed trays 7. It may be a light-shielding type optical sensor or a microswitch that performs a light-shielding operation by a shield plate or the like provided on the side portion. Similarly, the paper surface detection sensor 95 is
The present invention is not limited to the above, and may be a light-shielding type optical sensor that performs a light-shielding operation using a shielding plate or the like, or a microswitch.

Based on the signal from the intermediate detection sensor 4, the paper surface detection sensor 95 or the lower limit detection sensor 5,
As auxiliary means for surely stopping the paper feed tray 7 at the intermediate position P2 or the lower limit position P3, for example, Japanese Patent Laid-Open No. 1-1
Braking means shown in FIG. 1 of Japanese Patent No. 87125,
That is, a brake disc fixed to the other end of the output shaft of the tray lifting motor 11 and a holding solenoid (both not shown) for pressing a brake shoe against the brake disc for braking.
You may provide the structure which consists of.

Incidentally, in the above-mentioned embodiments and the like, the control means 60 for switching the lowering lower limit position of the paper feed tray 7 is provided according to the length of time the tray lowering key 67 is pressed, and the pressing time of the tray lowering key 67 is 3 seconds. If it is less than the intermediate position P2
The paper feed tray 7 is moved down to the lower limit position P3 if the pressing time of the tray lowering key 67 is 3 seconds or more. The pressing time is based on the above 3 seconds. Needless to say, other than 3 seconds desired by the user or the like may be used as the reference of the pressing time.

The left / right movement amount display is not limited to the above-mentioned means for mechanically displaying the movement amount by the left / right movement amount display 83, but a well-known movement amount detection sensor may be provided, for example.
Further, by providing an electrically operated left and right movement amount display in place of the left and right movement amount display 83, the control means 60 receives the movement amount signal from the movement amount detection sensor, and the control means 60 receives the electrically operated left and right movement amount. You may make it display a moving amount on a display. In this case, a sensor such as an encoder provided at the shaft end of the movable frame drive shaft 30 or a sensor using a variable resistor is used as the movement amount detection sensor, and an electrically operated left and right movement amount display is provided with, for example, An LED (light emitting diode) or LCD (liquid crystal display device) is used.

The worm 12 and the worm wheel 13a which constitute the tray elevating and lowering drive device 10 may be composed only of spur gears instead of them.

The biasing means is the spring 11 of the above embodiment.
The elastic member is not limited to 4, but may be an elastic member made of rubber or the like as long as it has the same spring characteristics and durability as the spring 114.

In the above-mentioned embodiments, the paper feed roller 2 is
Main body frame 1F in the paper feed section 58 of the stencil printing machine 1
Although it is disposed on the side, the invention is not limited to this and may be disposed on the side of the sheet feeding device 100.

The sheet feeding device 100 according to the above-described embodiment is
Although it is removably disposed on the main body frame 1F of the stencil printing apparatus 1, the present invention is not limited to this, and it goes without saying that it may be fixedly disposed on the main body frame 1F of the stencil printing apparatus 1.
Needless to say, the sheet feeding device 100 according to the above-described embodiments is not limited to the stencil printing device 1 and may be arranged as described above in an image forming apparatus such as a copying machine, a printing machine, a facsimile, and a printer. .

[0177]

As described above, according to the present invention, according to an invention of claim 1 and 2 wherein, by the construction and operation, when lowered to (1) input tray lower limit position (interrupt cassette loading position), The frame is interlocked so that the sheet feeding cassette can be inserted between the upper surface of the frame and the sheet feeding means of the image forming apparatus, and the cassette mounting space is formed, so that the sheet feeding cassette is inserted in the cassette mounting space. Can be attached. In addition, by having a dedicated paper stacking member driving means for raising and lowering the paper stacking member in the paper feed cassette,
It is no longer necessary to raise and lower the paper in the paper feed cassette with the frame, which eliminates the need for a drive mechanism for the paper feed operation in the frame and the need to place the paper feed cassette on the upper surface. , frame body since well only supports the side fences, an image forming apparatus and / or the paper feeding device can be simple structure in small type <br/>. (2) When feeding the paper feed cassette, the top surface of the frame escapes to the lower side of the paper feed cassette, and the paper feed cassette itself does not move up and down, but only the paper in the paper feed cassette moves up and down Since there is no business trip area in the space above the sheet feeding means of the forming apparatus, it is not necessary to provide an extra space here, and the height of the image forming apparatus itself can be suppressed. (3) Furthermore, a paper feed tray (multi-sheet feed tray) with and without a paper feed cassette
The on / off mechanism of can be switched on and off, so you can easily switch modes without the need for a mode switch key, etc. There is no problem that the device rises and interferes with the paper feed cassette to damage the device.

According to the third aspect of the present invention, the same effects as the above (1) to (2) of the first or second aspect of the invention can be obtained. You can limit the rise of the paper tray (multi-sheet feeder) to a small distance,
It is possible to prevent the apparatus from being damaged due to the interference between the sheet feeding tray (multi-sheet feeding table) and the sheet feeding cassette.

According to the fourth aspect of the invention, in addition to the effects of the first or second aspect of the invention, the sheet feeding cassette is mounted and the cover is closed, and the sheet feeding cassette is ready to start feeding. When completed, by raising the paper stacking member in the paper feed cassette, the uppermost paper is raised to the paper feed position, so after pressing the start key of the image forming apparatus,
It is possible to shorten the waiting time until the start of feeding.

According to the invention of claim 5, in addition to the effects of the invention of claim 1 or 2, when the cover is opened to switch to the multi-sheet feeding mode, the sheet stacking member in the sheet cassette is Since the descent is started, the waiting time for removing the paper feed cassette can be shortened.

According to the invention of claim 6, in addition to the effect of the invention of claim 5, the sheet stacking member is lowered in the apparatus until it reaches the lowest position. Therefore, when the sheet cassette is removed, the sheet cassette is removed. Since the own weight of the stacked paper inside is not applied to the paper stacking member driving means of the paper feed cassette, the operation force at the time of removal can be reduced, and at the moment of removal, the paper stacking member etc. suddenly drops to the lowest position. It can be removed smoothly and stably without giving shock.

According to the invention of claim 7, in addition to the effect of the invention of claim 5 or 6, when the arm is lowered to the lowest position at the time of detaching the paper feeding cassette, the driving mechanism or the driving force transmitting member is provided. Since the one-way clutch is built-in, the sheet stacking member driving means is used, and the driving force transmitting member is rotated in the loose rotation direction of the one-way clutch for a fixed time or a fixed distance sufficient for the arm to rotate to the lowest position. The arm can be stably driven to the lowest position with a simple mechanism and control regardless of where the sheet stacking member is stopped and without using a sensor or the like for detecting the lowest position of the arm. .

According to the invention described in claim 8, in addition to the effect of the invention described in claim 7, by providing a gap between the lower surface of the sheet stacking member and the upper surface of the arm, the sheet stacking member driving means is provided when the sheet cassette is removed. The upward rotation of the arm that occurs when the driven force transmission member is disconnected does not interfere with the sheet stacking member, and the drive mechanism is not subjected to a load due to the weight of the sheet during the same operation, and the sheet feeding cassette The pulling-out operation force at the time of removal does not increase, and it is possible to pull out smoothly.

According to the ninth aspect of the invention, in addition to the effects of the first or second aspect of the invention, when the sheet cassette is pulled out and the mode is switched to the multi-sheet feeding mode, the sheet surface detection means displays the sheet on the sheet tray. When the paper surface height position of the upper portion of the stacked paper sheets is detected, the paper feed tray is automatically stopped, so that the upper surface of the paper sheets stacked on the paper feed tray and the paper feeding means of the image forming apparatus are detected. Between 500 and 150 sheets
Since it is possible to provide a fixed space for supplying about 0 sheets, it is possible to easily supply the paper, the waiting time before the start of paper feeding is not too long, and the stack of paper remains on the paper feeding tray. Even if the amount becomes small, the paper feed tray is stopped at the same position, so that the waiting time does not become long.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a sheet feeding device in a stencil printing apparatus to which an embodiment of the present invention is applied.

FIG. 2 is an enlarged vertical cross-sectional view showing the sheet feeding device of the embodiment.

FIG. 3 is a vertical cross-sectional view showing an operation of feeding paper in a paper-full state in the paper feeding device of the embodiment.

FIG. 4 is a front view showing a structure around a tray elevating drive device and a frame body of the paper feeding device of the embodiment.

FIG. 5 is a perspective view showing a structure around a sheet feeding tray and a side fence of the sheet feeding device of the embodiment.

FIG. 6 is a vertical cross-sectional view showing the structure around the sheet feeding cassette and the operation in the state where the sheet feeding cassette is mounted in the embodiment.

FIG. 7 is a side sectional view of an essential part showing the paper feed cassette attaching / detaching mechanism of the embodiment.

FIG. 8 is a partially enlarged vertical cross-sectional view showing the periphery of the cassette tray lifting drive device of the embodiment.

FIG. 9 is a perspective view showing an overall appearance of the sheet feeding device of the embodiment.

FIG. 10 is a partial perspective view of a main part showing a configuration around a frame body, a side fence, and a paper feed tray of the embodiment.

FIG. 11 is a partial cross-sectional side view showing the configuration around the frame body, side fences, and paper feed tray of the embodiment.

FIG. 12 is a partial cross-sectional plan view showing a configuration of the frame body, the side fences, around the paper feed tray, and the paper feed cassette when the embodiment is mounted.

FIG. 13 is a perspective view showing a structure around a paper feed cassette in the embodiment.

FIG. 14 is a perspective view of an essential part showing a positioning mechanism of a paper feed cassette in the embodiment.

FIG. 15 is a front view of a main part showing an engaging operation of a driving force transmitting member and a driven force transmitting member of the sheet feeding cassette in the embodiment.

FIG. 16 is a block diagram showing an electrical control configuration of the embodiment.

FIG. 17 is a flowchart for determining whether the lowering end position of the sheet feeding tray is the sheet surface detection position or the lower limit position according to the pressing time of the lowering key in the embodiment.

FIG. 18 is a flowchart showing control of the raising / lowering operation of the tray raising / lowering drive device by the lowering flag to the lower limit position in the embodiment.

FIG. 19 is a flowchart showing the control of the raising / lowering operation of the tray raising / lowering drive device by the lowering flag to the sheet surface detection position in the embodiment.

FIG. 20 is a flow chart for determining the raising / lowering operation of the paper feed tray after turning on the power of the apparatus in the embodiment.

FIG. 21 is a flow chart for determining the raising / lowering operation of the paper feed tray after the power of the apparatus is turned on in the embodiment.

FIG. 22 is a partial cross-sectional side view showing the structure around the cover of the embodiment.

FIG. 23 is a perspective view of essential parts showing a configuration for detecting the paper size in the paper feed cassette in the embodiment.

FIG. 24 is a front cross-sectional view of an essential part showing the configuration for detecting the paper width of the paper on the paper feed tray in the embodiment.

FIG. 25 is a front view of the main parts showing the operation of the side fence frame lower limit detection sensor in the above-described embodiment.

FIG. 26 is a plan view of an essential part showing the operation of the side fence frame lower limit detection sensor in the above embodiment.

FIG. 27 is a front view showing the meshing operation of the gears as the driving force transmitting member and the driven force transmitting member of the embodiment.

FIG. 28 is an enlarged front view of the essential part showing the tooth tops of the gears as the driving force transmitting member and the driven force transmitting member of the embodiment.

FIG. 29 is a flowchart showing a raising drive process of the paper feed cassette or the paper feed tray in the embodiment.

FIG. 30 is a flowchart showing a rising drive process of the paper feed cassette or the paper feed tray in the embodiment.

FIG. 31 is a flowchart showing a rising drive process of the paper feed cassette or the paper feed tray in the embodiment.

FIG. 32 is a flowchart showing a rising drive process of the paper feed cassette or the paper feed tray in the embodiment.

FIG. 33 is a flow chart showing a rising drive process of the paper feed cassette or the paper feed tray in the embodiment.

FIG. 34 is a flow chart for determining the raising / lowering operation of the paper feed tray after the power of the apparatus is turned on in the embodiment.

FIG. 35 is a flow chart for determining the raising / lowering operation of the paper feed tray after the power of the apparatus is turned on in the embodiment.

FIG. 36 is a flow chart for determining the raising / lowering operation of the paper feed tray after the power of the apparatus is turned on in the embodiment.

FIG. 37 is a flow chart for judging the raising / lowering operation of the paper feed tray after the power source of the apparatus is turned on in the embodiment.

[Explanation of symbols]

1 Stencil printing machine as image forming apparatus 2 Paper feeding roller 3 as paper feeding means 3 Upper limit detection sensor 4 as upper limit detection means Intermediate detection sensor 5 as intermediate detection means Lower limit detection sensor 6, 6'paper as lower limit detection means 7 Paper Feed Tray as Large-Capacity Paper Feed Table 10 Tray Elevating / Driving Device as Tray Elevating / Driving Device 18 Movable Frames 20a, 20b Side Fence Pair 21 Side Fence Moving Axis on Frame 22 Frame Body Constituting side fence moving shaft lower 28 frame 39 sheet feed cassette 39S cassette mounting space 40 cassette tray elevating drive device 41 as sheet stacking member driving means sheet stacking plate 44 as sheet stacking member arm shaft as driven force transmitting member Gear 44a One-way clutch 45 Elevating arm drive gear 46 as a driving force transmission member Cassette tray raising / lowering drive motor 47 as driving means Paper feed cassette attaching / detaching mechanism 48a, 48b Cassette guide 58A as cassette supporting means Paper feed opening 60 Control means 65 Timer 67 Tray lowering key 83 as tray lowering setting means 83 Frame lower limit detecting means Side fence frame detection sensor 90 as cassette paper presence / absence detection sensor 91 as cassette paper presence / absence detection cassette presence / absence detection sensor 92 as cassette presence / absence detection means Cover opening / closing detection sensor 95 as paper opening / closing detection means Detection Sensor 100 Paper Feeding Devices 111a, 111b Coupling Member 114 Constituting Frame (Tension Coil) Spring Pa Upper Fixed Position Pb Lower Fixed Position Pc Cassette Lower Limit Position P1 Upper Limit Position P2 Intermediate Position P3 Lower Limit Position P4 Paper Surface Height Sheet surface detection position corresponding to the

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI B65H 1/26 310 B65H 1/26 310F 312 312A 1/28 320 1/28 320B 3/00 310 3/00 310D (56) Reference Documents JP-A-6-271124 (JP, A) JP-A-5-43062 (JP, A) JP-A 64-53937 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B65H 1/00-3/68

Claims (9)

(57) [Claims] 1. A sheet feeding device in an image forming apparatus having a sheet feeding port for separating the stacked uppermost sheets one by one at a sheet feeding position and feeding them in a sheet conveying direction. A casing for forming an outer frame of the sheet feeding device, and the casing for positioning both side edges of the sheet in a sheet width direction orthogonal to the sheet conveying direction provided inside the casing. A pair of side fences that can be moved up and down in the housing between an upper fixed position of the housing and a lower fixed position of the housing, and the side fence can be moved up and down between the upper fixed position and the lower fixed position. A frame body that supports the paper feed tray, a paper feed tray that can be raised and lowered between an upper limit position where the sheets are stacked and raised to face the paper feed position, and a lower limit position that is most lowered, and the side fence includes the upper portion. A feather that moves up and down between the fixed position and the lower fixed position. A lifting mechanism, a tray lifting drive mechanism for moving the paper feed tray between the upper limit position and the lower limit position, and an upper portion of the frame body when the paper feed tray is lowered to the lower limit position. A cassette mounting space for mounting a paper feeding cassette capable of storing a plurality of sheets is formed between the paper feeding means, and the paper feeding cassette detachably disposed in the cassette mounting space, From the upper limit position and the upper limit position, which is provided in the housing, detachably supports the paper feed cassette, and to stack the paper stored in the paper feed cassette to face the paper feed position. A sheet stacking member that can be lifted and lowered between the farthest cassette lower limit position, a sheet stacking member driving unit that selectively moves the sheet stacking member up and down between the upper limit position and the cassette lower limit position, and the cover. A cassette presence / absence detecting means for detecting presence / absence of loading of the paper feeding cassette in the set loading space; When the sheet stacking member is raised and the tray elevating and lowering driving means is prohibited from driving, and the cassette presence / absence detecting means does not detect the mounting of the sheet feeding cassette, the tray elevating and lowering driving means is used to perform the sheet feeding. A sheet feeding device in an image forming apparatus, comprising: a control unit that raises a tray. 2. The sheet feeding device in the image forming apparatus according to claim 1, further comprising: a lower limit detecting unit that detects the lower limit position of the sheet feeding tray, wherein the control unit uses the cassette presence / absence detecting unit. When the mounting of the paper cassette is detected and the lower limit detection unit detects the lower limit position of the paper feed tray, the sheet stacking member driving unit is operated to raise the sheet stacking member and When the driving of the tray elevating drive means is prohibited, and the paper feed cassette is not detected by the cassette presence / absence detection means, after the tray elevating drive means is operated to raise the paper feed tray for a predetermined time. If the lower limit detection means does not detect the lower limit position of the paper feed tray, the tray elevating drive means is used to raise the paper feed tray. After the tray elevating and lowering drive means has raised the paper feed tray for a predetermined time, and when the lower limit position of the paper feed tray is detected by the lower limit detection means, the tray up and down drive means is operated. A sheet feeding device in an image forming apparatus, wherein the raising of the sheet feeding tray is stopped. 3. A sheet feeding device in an image forming apparatus having a single sheet feeding means for separating the stacked uppermost sheets one by one at a sheet feeding position and feeding them in a sheet conveying direction. A casing for forming an outer frame of the sheet feeding device, and the casing for positioning both side edges of the sheet in a sheet width direction orthogonal to the sheet conveying direction provided inside the casing. A pair of side fences that can be moved up and down in the housing between an upper fixed position of the housing and a lower fixed position of the housing, and the side fence can be moved up and down between the upper fixed position and the lower fixed position. A frame body that supports the paper feed tray, a paper feed tray that can be raised and lowered between an upper limit position where the sheets are stacked and raised to face the paper feed position, and a lower limit position that is most lowered, and the side fence includes the upper portion. A feather that moves up and down between the fixed position and the lower fixed position. A lifting mechanism, a tray lifting drive mechanism for moving the paper feed tray between the upper limit position and the lower limit position, and an upper portion of the frame body when the paper feed tray is lowered to the lower limit position. A cassette mounting space for mounting a paper feeding cassette capable of storing a plurality of sheets is formed between the paper feeding means, and the paper feeding cassette detachably disposed in the cassette mounting space, From the upper limit position and the upper limit position, which is provided in the housing, detachably supports the paper feed cassette, and to stack the paper stored in the paper feed cassette to face the paper feed position. A sheet stacking member that can be moved up and down between a separated cassette lower limit position, a sheet stacking member drive unit that selectively moves the sheet stacking member up and down between the upper limit position and the cassette lower limit position, and the frame body A frame lower limit detecting means for detecting a frame lower limit position, a cassette paper presence / absence detecting means for detecting the presence / absence of the paper stored in the paper feed cassette, and the frame lower limit detecting means for the frame body of the frame body. When the lower limit position is detected and the cassette paper presence / absence detecting means detects the paper in the paper feeding cassette, the paper stacking member driving means is operated to raise the paper stacking member to stack the paper. The sheet on the member can be fed at the sheet feeding position, the driving of the tray elevating / lowering means is prohibited, and the frame lower limit detecting means detects the frame lower limit position of the frame, When the cassette sheet presence / absence detecting unit does not detect the sheet in the sheet feeding cassette, the tray raising / lowering driving unit allows the raising / lowering of the sheet feeding tray, and the tray raising / lowering driving unit operates the sheet feeding tray. of Even if the descending operation is driven for a certain period of time or so as to raise or lower the amount of elevation of the paper feed tray by a certain amount, the detection state of the frame lower limit position of the frame by the frame lower limit detection means is not detected If no change in state, the sheet feeding device in an image forming apparatus characterized by and a control means for stopping the paper feed tray and the tray elevating drive means. 4. The paper feeding device of the image forming apparatus according to claim 1, wherein the paper feeding cassette is attached / detached so as to cover an opening of the housing opening to the cassette mounting space. An openable / closable cover for loading / unloading a paper into / from a paper feed tray and the paper feed cassette; a cover open / close detection unit for detecting an open / closed state of the cover; An upper limit detection means for detecting the position of the paper or the uppermost paper stacked on the paper stacking member, and the control means detects the mounting of the paper feed cassette by the cassette presence / absence detection means, Further, when the cover open / close detecting unit detects the closed state of the cover, the sheet stacking member driving unit is operated to raise the sheet stacking member to move the sheet stacking member. A sheet feeding device in an image forming apparatus, wherein the upper sheet can be fed at the sheet feeding position. 5. The paper feeding device in the image forming apparatus according to claim 1, wherein the paper feeding cassette is attached / detached so as to cover an opening of the housing opening in the cassette mounting space, An openable / closable cover for loading / unloading a paper into / from a paper feed tray and the paper feed cassette; a cover open / close detection unit for detecting an open / closed state of the cover; An upper limit detection means for detecting the position of the paper or the uppermost paper stacked on the paper stacking member, and the control means detects the mounting of the paper feed cassette by the cassette presence / absence detection means, In addition, when the cover open / close detecting unit detects the opened state of the cover, the sheet stacking member driving unit is operated to lower the sheet stacking member. Paper feeding device in the image forming apparatus. 6. The sheet feeding device in the image forming apparatus according to claim 5, wherein the control unit drives the sheet stacking member driving unit to lower the sheet stacking member and at least the sheet stacking member is operated. A sheet feeding device in an image forming apparatus, which is configured to reach a lower limit position of a cassette. 7. The sheet feeding device in the image forming apparatus according to claim 5, wherein the sheet stacking member driving means is a driving means arranged in the casing, an inner surface of the casing, and A driving force transmitting member for transmitting the driving force of the driving unit to the sheet stacking member, the driving force transmitting member being arranged at a position that avoids interference with the sheets stacked on the sheet feeding tray at the maximum; Is provided with a driven force transmitting member that selectively engages with the driving force transmitting member and raises and lowers the sheet stacking member, and to either one of the driving force transmitting member or the driven force transmitting member, The control means is provided with a one-way clutch arranged so that the driving force is transmitted in a rising direction of the sheet stacking member and the loosening direction is not transmitted in a descending direction of the sheet stacking member. Is the paper stack When the sheet stacking member is lowered by driving the member driving means, the sheet stacking member is at least a fixed time longer than the time required for the sheet stacking member to reach the cassette lower limit position from the upper limit position. A sheet feeding device in an image forming apparatus, characterized in that the sheet stacking member is lowered by driving means. 8. The sheet feeding device in the image forming apparatus according to claim 7, wherein the driving force transmission member is provided with an arm for moving up and down the sheet stacking member, and the sheet stacking member is the sheet stacking member. Between the lower surface of the sheet stacking member engaging with the arm and the upper surface of the arm when the lower limit position of the cassette is reached and the paper cassette is removed from the cassette supporting means. A sheet feeding device in an image forming apparatus, wherein a gap structure is provided in a range that allows the engagement between the driving force transmitting member and the sheet stacking member to be released. 9. The paper feeding device in the image forming apparatus according to claim 1, further comprising a paper surface detecting unit for detecting a paper surface height position of an upper portion of the paper stacked on the paper feeding tray, When the apparatus is powered on and the cassette presence / absence detection unit does not detect the mounting of the paper feed cassette, the control unit drives the tray lifting / lowering drive unit based on a signal from the paper surface detection unit. The paper feeding device in the image forming apparatus, wherein the paper feeding tray is stopped at the paper surface height position.