JPH08217267A - Paper feeding device in image forming device - Google Patents

Abstract

PURPOSE: To secure the space for jam processing by making use of one tray lowering key, by providing a tray lowering setting means for setting the lowering amount of a paper feeding tray, and stopping the paper feeding tray in the lower limit position through a process of operating the tray lowering setting means for the set time or more. CONSTITUTION: A stencil printer is provided with a tray raising/lowering driving device 10 for raising/lowering a paper feeding tray between the upper limit position and the lower limit position and controls the operation of it through a CPU 63. This CPU 63 has a function for controlling the paper feeding tray on the basis of a signal from an intermediate detecting sensor 4 so that it may be stopped in the intermediate position. Moreover, it has a function for controlling the paper feeding tray 7 on the basis of a signal from a lower limit detecting sensor 5 so that it may be stopped in the lower limit position after the paper feeding tray is lowered to the lower limit position by driving the tray raising/lowering driving device 10 when a tray lowering key 67 is operated for the set time (for example, three minutes) or more. Therefore, the space effective in jam processing can be secured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention separates and feeds a plurality of sheets stacked on a sheet feed tray or the like one by one to an image forming apparatus such as a copying machine, a printing machine, a facsimile, and a printer. The present invention relates to a sheet feeding device, and more specifically, to a tray elevating type sheet feeding device in which the sheet feeding tray and the like move up and down.

[0002]

2. Description of the Related Art A large number of sheets of paper are stacked and raised, and a paper feed tray that can be raised and lowered between an upper limit position facing a paper feed position and a lower limit position that is most lowered, and a paper feed tray between the upper limit position and the lower limit position. Large-scale paper feed unit type equipped with a paper feed tray raising / lowering drive means for moving the paper tray, and a paper feed means for separating and feeding the uppermost paper stacked in the paper feed tray one by one at the paper feed position Sheet feeding devices are known.

In such a sheet feeding device of the large sheet feeding unit type, it is necessary to lower the sheet feeding tray for a certain distance for jam clearance and paper replenishment when a jam occurs.
As disclosed in Japanese Patent No. 187125, a sheet material detection sensor (upper limit detection means) for detecting the position of the uppermost sheet material (paper sheet) stacked on a lifter (paper feed tray) and a lifter (paper feed tray). Lifter (paper feed tray) to stop the lifter (paper feed tray) at a predetermined intermediate stop position (intermediate position) between the third detection switch (lower limit detection means) for detecting the lower limit position of Has a first detection switch 13 and a second detection switch 14 (intermediate detection means) for detecting the position of, and based on a signal from the intermediate detection means,
A device having a control means for stopping the paper feed tray at an intermediate position has been developed.

Further, for example, JP-A-6-271118, 2
As disclosed in Japanese Patent No. 71119,271120, an interrupt cassette (paper feeding cassette) type large-volume paper feeding unit capable of selecting a multi-sheet feeding and a cassette feeding, and the same pickup roller (paper feeding means) A paper feeding device that feeds paper using a paper feeding roller is proposed. This is a cassette base as a first paper feed tray that is provided on the top of the paper feed unit and has a notch portion that can pass through while avoiding the paper feed roller when moving up and down together with the paper feed unit; A multi-sheet feed tray (paper feed tray) as a second paper feed tray, which is vertically movable with respect to the paper feed unit, is moved up and down by separate lifting drive mechanisms in the same frame. It is like this.

[0005]

However, in the former case, the second detection switch is operated in a state where the uppermost paper stacked in the paper feed tray is in contact with the paper feed roller (pickup roller) and the paper is full. When a paper jam occurs near the paper feed roller when the paper feed tray is stopped at the intermediate position detected by 14, the paper feed tray is moved to the lower limit position in order to create a space for jam processing. A startup switch (tray lowering key as a tray lowering setting means) is required to lower the temperature. In addition, cost reduction is achieved by using a single paper feed roller, and by using the same paper feed mechanism as the paper feed unit, an interrupt paper feed cassette type that can support high speed paper feed without complicating the paper transport path In the case of providing the sheet feeding device, it is necessary to lower the sheet feeding tray to the lower limit position to create a space for storing the sheet feeding cassette. For this reason, in addition to providing the above-mentioned start-up switch, a new device such as a paper feed cassette mode switch for lowering the paper feed tray to the lower limit position to create a space for storing the paper feed cassette is newly required. However, there is a problem in that the cost increases as the number increases.

In the latter, a paper feed unit elevating drive mechanism including a drive shaft A for vertically moving a paper feed unit and a paper feed cassette, and a paper feed shaft including a drive shaft B for vertically moving a paper feed tray. There is a problem that two complicated lifting and lowering drive mechanisms of the tray lifting and lowering drive mechanism are required. Furthermore, when the paper feed tray is used, the cassette stand installed above the paper feed unit has a structure that rises above the paper feed rollers, so a space for housing the cassette stand is required above the paper feed rollers. The stencil printing apparatus main body is usually provided with a plate discharge section, a plate making section, etc., and securing such a space is not preferable because the stencil printing apparatus and the sheet feeding apparatus become large in size. is there.

Therefore, according to the present invention, in order to solve such a problem, one tray lowering key is used to provide a space for jam processing and a sheet feeding cassette interruption, and an elevating drive for raising and lowering the sheet feeding tray. An object of the present invention is to provide a sheet feeding device in an image forming apparatus that can simplify the means and can downsize the image forming apparatus and the sheet feeding device.

[0008]

In order to achieve the above-mentioned object, the invention according to claim 1 has an upper limit position where a plurality of sheets are stacked and raised to face a sheet feeding position, and a lower limit position where the sheet is lowered most. Between the upper and lower limit positions, a sheet feed tray elevating and lowering drive unit for moving the sheet feed tray between the upper limit position and the lower limit position, and the sheet feed tray loaded at the sheet feed position. A sheet feeding unit that separates and feeds the uppermost sheet one by one, a lower limit detection unit that detects the lower limit position of the sheet feed tray, and a sheet feeding unit that detects the uppermost sheet stacked on the sheet feed tray. An upper limit detection unit for detecting a position, and an intermediate detection for detecting the position of the paper feed tray in order to stop the paper feed tray at a predetermined intermediate position between the upper limit detection unit and the lower limit detection unit. Means and the signal from the intermediate detection means A sheet feeding device in an image forming apparatus that feeds the sheet on the sheet feeding tray at the sheet feeding position, the sheet feeding device including a control unit that stops the sheet feeding tray at the intermediate position. There is a tray lowering setting means for setting the descending amount of the tray by operating for a predetermined time, and by operating the tray lowering setting means for a predetermined time or more, the control means,
Based on a signal from the lower limit detection means, the paper feed tray raising / lowering drive means is caused to stop the paper feed tray at the lower limit position.

According to a second aspect of the present invention, in the sheet feeding device of the image forming apparatus according to the first aspect, when the sheet feeding tray reaches the intermediate position, the intermediate detecting unit does not detect the sheet feeding tray. When the paper feed tray reaches the lower limit position, the control means causes the paper feed tray lifting drive means based on a signal from the lower limit detection means to move the paper feed tray to the lower limit position. It is characterized by stopping at.

According to a third aspect of the present invention, in the sheet feeding device of the image forming apparatus according to the first or second aspect, there is provided a sheet feeding cassette which is disposed near the lower portion of the sheet feeding means and can store a plurality of sheets. A sheet feeding cassette attaching / detaching mechanism that detachably supports the sheet feeding cassette, and an elevating mechanism that exposes the sheets stored in the sheet feeding cassette to the sheet feeding position. Is configured to feed the paper on the paper feed tray at the paper feed position, and feed the paper from the paper feed cassette at the paper feed position when the paper feed cassette is mounted.

According to a fourth aspect of the present invention, in the sheet feeding device of the image forming apparatus according to the first, second or third aspect, the intermediate detecting means is located between the upper limit detecting means and the lower limit detecting means. It is characterized in that it has an intermediate detecting means moving and holding mechanism for moving and holding it to a position.

[0012]

According to the first aspect of the present invention, with the above construction, the tray lowering setting means is operated for a predetermined time or longer, whereby the control means feeds paper based on the signal from the lower limit detection means. The tray elevating drive means is used to stop the paper feed tray at the lower limit position.

According to the second aspect of the invention, in addition to the operation of the first aspect, when the paper feed tray reaches the intermediate position, the intermediate detection means does not detect the paper feed tray, and the paper feed tray is at the lower limit. When the position is reached, that is, when the intermediate detection unit does not operate due to a failure or the like, the control unit controls the paper feed tray elevating drive unit to move the paper feed tray to the lower limit position based on the signal from the lower limit detection unit. Stop.

According to the third aspect of the present invention, in addition to the functions of the first or second aspect of the invention, the sheet on the sheet feed tray is fed at the sheet feed position when the sheet cassette is not installed. , When the paper feed cassette is installed, the paper is fed from the paper feed cassette at the paper feed position.

According to the invention described in claim 4,
In addition to the respective actions described in 2 or 3, the intermediate detecting means moving and holding mechanism moves and holds the intermediate detecting means at an arbitrary position between the upper limit detecting means and the lower limit detecting means.

[0016]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

(Embodiment 1) Embodiment 1 of the invention according to claim 1 will be described with reference to FIGS. 1 to 5 and 9. 1 and 2, reference numeral 1 indicates a stencil printing apparatus as an image forming apparatus. Reference numeral 1F is a stencil printer 1
The body frame of is shown. Reference numeral 100 is the main frame 1F
2 illustrates a sheet feeding device that is detachably disposed on one side portion.

The paper feeding device 100 has a paper feeding tray 7 which can be raised and lowered between an upper limit position P1 where a plurality of sheets of paper 6 are stacked and raised to face the paper feeding position and a lower limit position P3 which is lowered most, and an upper limit position. A tray elevating and lowering drive device 10 as a paper feed tray elevating and lowering drive means for moving the paper feed tray 7 between P1 and the lower limit position P3, and the uppermost paper 6 stacked on the paper feed tray 7 at the paper feed position. A paper feed roller 2 as a paper feed means for separating and feeding the sheets one by one, and a tray down key 67 as a tray down setting means for setting the descent amount of the paper feed tray 7 for a predetermined time (FIG. 9). (Only shown), a lower limit detection sensor 5 as a lower limit detection means for detecting the lower limit position P3 of the paper feed tray 7, and an upper limit detection means for detecting the position of the uppermost sheet 6 stacked on the paper feed tray 7. Upper limit detection sensor 3 of An intermediate detection sensor 4 as an intermediate detection means for detecting the position of the paper feed tray 7 in order to stop the paper feed tray 7 at a predetermined intermediate position P2 between the detection sensor 3 and the lower limit detection sensor 5, Intermediate detection sensor 4
It mainly comprises a control means 60 (shown only in FIG. 9) for stopping the paper feed tray 7 at the intermediate position P2 on the basis of the signal from. As described below, the sheet feeding device 100 has a structure capable of stacking about 3000 to 4000 sheets of paper 6 on a sheet feeding tray 7 at a time and moving up and down, and a so-called LCT unit (large capacity sheet feeding unit). ).

The stencil printing machine 1 has a known structure similar to the structure described in Japanese Patent Application Laid-Open No. 5-229243 already 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 indicates a print drum portion for printing on the paper 6 by winding a plate-making master (not shown) on the outer peripheral surface, and reference numeral 58 indicates the print drum portion for the paper 6 stacked on the paper feed tray 7 in the paper feeding device 100. The paper feeding unit for sending to 53 is denoted by reference numeral 59.
Is a paper discharge unit for discharging the printed paper 6a printed by the print drum unit 53 to the paper discharge tray 59a, and reference numeral 56 is provided to face the plate making / plate supplying unit 54 with the print drum 57 interposed therebetween. Each of the stencil ejection parts for ejecting a used stencil master stripped from the outer peripheral surface of the printing drum 57 to a stencil ejection box (both not shown) is shown. The print drum unit 53 corresponds to the image forming unit of the image forming apparatus.

The paper feed roller 2, the paper feed tray 7, the tray lifting / lowering drive device 10, the upper limit detection sensor 3, the intermediate detection sensor 4, the lower limit detection sensor 5, the tray lowering key 67, and the control means 60 will be sequentially described below. In addition, in FIG. 3 and FIG. 4, in order to simplify the drawing, the side fence pair 20
Illustration of a and 20b is abbreviate | omitted, and illustration of the upper limit detection sensor 3 is abbreviate | omitted in FIG. 1 to 4 and 6, the upper limit detection sensor 3, the intermediate detection sensor 4, and the lower limit detection sensor 5 are schematically shown in a simplified form.

The paper feed roller 2 swings to a free end portion of the arm via a rotation driving shaft of a separation roller 52 rotatably supported by a paper feed side plate on the side of the main body frame 1F via an arm (both not shown). It is movable and rotatable. The paper feed roller 2 has, for example, a configuration similar to that of the paper feed roller 5 described in Japanese Utility Model Publication No. 5-18342. Reference numerals 51a and 51b denote separation roller pairs, and reference numerals 52a and 52b denote registration roller pairs.

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. A movable frame 18 is disposed above the fixed frame 26 so as to be movable in the paper width direction, which is a direction perpendicular to the paper transport direction X. The movable frame 18 has a substantially box-like shape. The side plates 18c and 18d provided (hereinafter sometimes referred to as "side plate pair 18c and 18d") and the side plate bottom 18e fixed to the side plate pairs 18a and 18b and the side plate pairs 18c and 18d. Consists of.

Fixed side plate pair 26a, 26b and side plate pair 18
A movable frame guide shaft 31 and a movable frame drive shaft 30, which are arranged parallel to each other in the paper width direction, are provided through the a and 18b, respectively. A male screw (not shown) is formed substantially at the center of the movable frame drive shaft 30, while a guide holder (not shown) having a female screw that meshes with the male screw is fixedly provided at the substantially center of the fixed frame 26. Has been done. A movable frame drive motor 32 is fixedly installed near one end of the movable frame drive shaft 30 in the movable frame 18. The movable frame drive motor 32 is connected to one end of the movable frame drive shaft 30 via a speed reduction mechanism including a speed reduction gear train, and drives the movable frame drive shaft 30 to rotate. When a left / right moving key (both not shown) of the operation panel arranged at a predetermined position of the sheet feeding device 100 is pressed, the movable frame drive motor 32 is rotationally driven, and the movable frame 18 is fixed by the screw mechanism. 26 is moved relative to the sheet width direction. Therefore, the sheet 6 is moved in the sheet width direction together with the movable frame 18 with respect to the main body frame 1F, and the image position in the sheet width direction during printing can be adjusted.

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. Tray notches 7a and 7b are formed in the paper feed tray 7 at a substantially central portion in the paper width direction Y. The lower left and right walls of the rear portion of the sheet feeding tray 7 and the lower left and right walls of the tray cutouts 7a and 7b of the sheet feeding tray 7 are parallel to each other in the sheet width direction Y and in the sheet width direction Y.
A pair of front and rear tray drive shafts 8a and 8b, which are long, are fixedly installed. In addition, a pair of left and right side fences 20a and 20b (hereinafter sometimes referred to as "side fence pair 20a, 20b") for positioning the paper 6 in the paper width direction Y are formed in the tray notches 7a and 7b. It is provided so as to be movable in the direction Y and movable in the up-and-down direction Z, which is a direction perpendicular to the paper transport direction X and the paper width direction Y.

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 ascending / descending direction Z and long in the ascending / descending direction Z. Guide groove 25, 2
The tray drive shaft 8b penetrates through 5 through a guide sleeve 8g described later. The guide sleeve 8g is formed between the side fence guide grooves 25, 25 and the tray drive shaft 8b, and a flange-shaped portion having an outer diameter larger than the width of the side fence guide groove 25 and guiding the drive shaft 8b in the up-and-down direction Z. And a sleeve portion that is loosely fitted to the tray drive shaft 8b and is slidable in the paper width direction Y of the tray drive shaft 8b.
On the other hand, through holes 20h that loosely fit the upper side fence moving axis 21 and the lower side fence moving axis 22 are formed in the rear portions of the side fence pairs 20a and 20b, respectively. Y
It is designed to be slidable on. In this way, each tray cutout portion 7 formed in the paper feed tray 7
By a and 7b, the movement of the side fence pair 20a, 20b is not obstructed, and the side fence pair 20a, 20b is against the tray drive shaft 8b, the side fence moving shaft upper side 21 and the side fence moving shaft lower side 22. By sliding it, the paper 6 can be positioned in the paper width direction Y according to the size of the paper used.

A pair of side plates 18a, 18b of the movable frame 18
As shown in detail in FIG. 4, each tray drive shaft 8a,
Drive shaft guide grooves 9a and 9b, which are longer than the side fence guide groove 25 in the up-down direction Z, for guiding the 8b in the up-down direction Z are formed in parallel with each other. Between the drive shaft guide groove 9a and the drive shaft guide groove 9b in the pair of side plates 18a, 18b, the side fence moving shaft 2 is provided.
1. A moving shaft guide groove upper portion 23 and a moving shaft guide groove lower portion 24, which are formed to be shorter than the side fence guide groove 25 in the ascending / descending direction Z, for guiding the side fence moving shaft lower portion 22 in the ascending / descending direction Z, are formed. There is. The side plate 18d is provided with a paper feed tray cover (not shown) that opens and closes when the paper 6 is replenished in the paper feed tray 7 or when jamming during paper feeding. Further, as shown in FIGS. 1 to 3, a cover top 19 is provided above the paper feed tray cover so as to be openable and closable via a hinge (not shown) attached to the side plate 18b.

Between the upper part of the side plate 18a and the upper part of the side fence 20a, and between the upper part of the side plate 18b and the side fence pair 20b.
A tension spring (not shown) is provided between and, and the pair of side fences 20a and 20b are always urged upward with respect to the movable frame 18. Therefore, as the paper feed tray 7 rises, the paper feed tray 7 and the side fence pairs 20a and 20b ascend to the positions shown in FIGS. 1 and 2 and stop. 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 raised relative to the pair of side fences 20a and 20b, and even the last one of the sheets 6 stacked on the sheet feeding tray 7 is brought into contact with the sheet feeding roller 2 to reliably feed the sheet. can do.

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 drive motor 11 fixed to the motor mounting member 18f formed integrally with a, the drive gear 12 fixed to the output shaft end of the drive motor 11, and the side plate pair 18a penetrating the side plate pair 18a, 18b. , 18b that are rotatably supported by the drive pulley shaft 15s, the drive pulleys 15 fixed on both ends, the drive pulley gear 14 fixed on the drive pulley 15, the drive gear 12 and the drive pulley gear 14 on the side plate 18a. And an idler gear 13 that is provided between the drive gear 12 and the drive pulley gear 14 and meshes with the drive gear 12, and an intermediate pulley 16 that is rotatably disposed at predetermined positions of the pair of side plates 18a and 18b.
a-16e, the drive pulley 15 and the intermediate pulley 16a-
A drive belt 17 wound around 16e, and belt stays 17a and 17b fixed to the drive belt 17 at predetermined positions to attach and fix both ends of each tray drive shaft 8a and 8b.
Mainly consists of and. Drive motor 11 and drive gear 1
2, the tray elevating and lowering drive device 10 except the drive pulley gear 14 and the idler gear 13 is omitted in FIG. 4, but the same structure as described above is also provided on the side plate 18b side.

The drive motor 11 is a DC motor that 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 drive motor 11 is electrically connected to a control means 60, which will be described later, via an electric circuit (not shown), and is controlled by the control means 60 in the manner described later.

With the above-described structure, when the drive motor 11 is driven to rotate in the clockwise direction, the drive pulley 1, the idler gear 13, and the drive pulley gear 14 are used to drive the drive pulley 1.
5 is also rotated in the same direction, and both ends of the tray drive shafts 8a and 8b fixed to the drive belt 17, that is, the paper feed tray 7 are raised at a constant speed. On the contrary, drive motor 1
When 1 is driven counterclockwise in the reverse 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 parallel with the paper transport direction X while maintaining a substantially horizontal state.

The upper limit detection sensor 3 is a proper paper feed position, that is, an upper limit position, in which the paper feed roller 2 comes into contact with the uppermost paper sheet 6 stacked on the paper feed tray 7 with an appropriate pressure to feed the paper. Detect P1. The upper limit detection sensor 3 is a well-known light-shielding type optical sensor having a light emitting portion and a light receiving portion, and has an abutting piece that abuts the uppermost sheet 6 stacked on a sheet feeding tray 7 in a swingable manner. In preparation for this, the light shielding plate provided in conjunction with the contact piece performs the light shielding operation between the light emitting portion and the light receiving portion to detect the upper limit position P1. 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 the same configuration as the optical sensor PS2 shown in FIG. 3 and the like described in JP-A-2-265825, for example.

Intermediate detection sensor 4 and lower limit detection sensor 5
Is a well-known reflection type optical sensor which has a light emitting portion and a light receiving portion which are respectively arranged at predetermined positions inside the side plate 18a.
The intermediate detection sensor 4 and the lower limit detection sensor 5 detect the intermediate position P2 or 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 upper limit detection sensor 3, the intermediate detection sensor 4, and the lower limit detection sensor 5 are electrically connected to the control means 60. The intermediate detection sensor 4 is arranged inside the side plate 18a 100 mm above the position where the lower limit detection sensor 5 is arranged.

The tray lowering key 67 is arranged on the operation panel.

A control configuration for controlling the operation of the sheet feeding device 100 will be described with reference to FIG. In the figure, the control components indicated by the broken lines are those not used in the first embodiment. In the figure, reference numeral 60 indicates a control means.
The control means 60 includes an I / O (input / output) port 64, a CPU
It comprises a central processing unit 63, a ROM (read only memory) 61, a RAM (readable and writable memory) 62, a timer 65, etc., and a microcomputer having a configuration in which these are connected by a signal bus. The control unit 60 is provided on a board (not shown) arranged at a predetermined position of the main body frame 1F of the stencil printing apparatus 1.

On / off signals and data signals from the upper limit detection sensor 3, the intermediate detection sensor 4, the lower limit detection sensor 5 and the tray lowering key 67 are transmitted to the input port of the control means 60. The command signal of the control means 60 is transmitted to the drive motor 11 of the tray lift drive device 10 via the output port.

The control means 60 includes an upper limit detection sensor 3, an intermediate detection sensor 4, a lower limit detection sensor 5, and a tray lowering key 67.
Command signals and / or on / off signals and data signals are transmitted / received to / from the drive motor 11 of the tray elevating / lowering drive device 10, and operations such as start, stop and timing of the stencil printing device 1 and the paper feeding device 100 are performed. It controls the entire system.

The drive start timing of the normal rotation (clockwise rotation) of the drive motor 11, that is, the rising start timing of the paper feed tray 7, is controlled by the control means 60 by a print start key (not shown) on the operation panel above the main body frame 1F. (Provided) is set when is pressed. The reverse rotation (counterclockwise rotation) drive start timing of the drive motor 11, that is, the lowering start timing of the paper feed tray 7 is controlled by the control means 60 by the tray lowering key 67.
It is set when is pressed.

In addition to the above-mentioned function of stopping the paper feed tray 7 at the intermediate position P2 based on the signal from the intermediate detection sensor 4, the CPU 63 sets the tray lowering key 67 to a predetermined time (this embodiment). 1) for 3 seconds or more), the drive motor 11 of the tray elevating / lowering drive device 10 is operated based on the signal from the lower limit detection sensor 5 without taking in the signal from the intermediate detection sensor 4 and the sheet feeding tray 7 is moved. It has a function of stopping at the lower limit position P3.

The timer 65 measures the pressing time of the tray lowering key 67 fetched through the input port of the control means 60 and outputs it to the CPU 63 at any time. Also 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 in the vicinity of the paper feed roller 2.

In the ROM 61, 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.

At the same time as the well-known operations of the stencil printing apparatus 1, that is, the plate discharge operation, the original image reading operation, and the plate making / plate making operation, the test printing is performed, and when the print start key is pressed, the same process as the test printing is performed. Then, the steps of feeding, printing, and ejecting are repeated for the set number of printed sheets, and the stencil printing step is completed.

The paper feeding process is started by pressing the print start key, and is performed by sending a paper feeding command signal from the control means 60 to the paper feeding device 100 of the paper feeding unit 58. When the paper feed command signal is transmitted from the control means 60,
The drive motor 11 is driven to rotate normally, and the paper feed tray 7 is raised. 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 control means 60 causes the drive motor 11 to operate. When the drive stop signal is transmitted, the normal rotation drive of the drive motor 11 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 known paper feed operation by the paper feed roller 2 continues. Be started.

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.

Since the first embodiment is provided with the above-described structure and is provided with the control means 60 for switching the lower limit lowering position of the paper feed tray 7 in accordance with the length of time the tray lowering key 67 is pressed, the tray lowering key 67 is controlled. If the pressing time is less than 3 seconds, the paper feeding tray 7 can be lowered to the intermediate position P2, and if the pressing time of the tray lowering key 67 is 3 seconds or more, the paper feeding tray 7 can be lowered to the lower limit position P3. is there.

In FIG. 12, the lowering operation end position of the paper feed tray 7 is set to the intermediate position P depending on the pressing time of the tray lowering key 67.
It is a flow chart which judges whether it is 2 or the lower limit position P3. First, the flow of processing when the tray down key 67 is pressed for 3 seconds or more will be described. Step S
When it is determined in 10 that the tray lowering key 67 is 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
To descend to the lower limit position P3, the process proceeds to step S12, and the "descent flag to lower limit position P3" is turned on. Next, in step S14, the "down flag to intermediate position P2" 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 sheet feeding tray 7 is lowered to the intermediate position P2, the process proceeds to step S13, and the "lowering flag to the intermediate position P2" is turned on.

FIG. 13 is a flowchart 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 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. 14 is a flow chart showing the control of the tray elevating and lowering drive device 10 by the "down flag to the intermediate position P2". First, when it is determined in step S20 that the "down flag to the intermediate position P2" is turned on,
In step S21, the drive of the tray elevating and lowering drive device 10 is started (the lowering operation of the paper feed tray 7 is started). afterwards,
In step S22, it is determined whether or not the paper feed tray 7 has reached the intermediate position P2, and the tray elevating drive device 10 is driven (the paper feed tray 7 until the paper feed tray 7 reaches the intermediate position P2.
Lowering operation). When it is determined in step S22 that the paper feed tray 7 has reached the intermediate position P2, the process proceeds to step S23 and the "fall flag to the intermediate position P2".
Is turned off, and then the process goes to step 24 to stop the drive of the tray elevating and lowering drive device 10 to complete the lowering operation of the paper feed tray 7.

For example, the position of the paper feed tray 7 is the position shown in FIGS. 1 and 2, and the uppermost paper 6 stacked on the paper feed tray 7 is in contact with the paper feed roller 2. When it is desired to lower the paper feed tray 7 for paper jamming and paper 6 replenishment in the vicinity of the paper feed roller 2,
The following operation is performed. First, the tray lowering key 67
When is pressed for less than 3 seconds, the drive motor 11 is reversely driven by the control means 60 based on the ON signal of the tray lowering key 67, and the paper feeding tray 7 is lowered. When the paper feed tray 7 is lowered and the intermediate detection sensor 4 detects the paper feed tray 7 at the position where the paper feed tray 7 reaches the intermediate position P2, a drive stop signal is transmitted from the control means 60 to the drive motor 11 to drive the drive motor. The reverse drive of 11 is stopped, and the paper feed tray 7 is held at the intermediate position P2. Therefore, without jamming the paper feed tray 7 unnecessarily, it is possible to check for jams, remove jammed paper, or remove paper 6 for jam processing.
Can be replenished. In addition, since the paper feed tray 7 in this state is stopped at the intermediate position P2 which is 100 mm above the lower limit position P3, and the ascending distance of the paper feed tray 7 is relatively short, the user can wait a relatively short time. The paper feeding operation can be restarted.

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 longer, and the control means 60 drives the drive 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 position where it reaches the lower limit position P3, the control means 6 is provided.
When the drive stop signal is transmitted from 0 to the drive motor 11, the reverse drive of the drive motor 11 is stopped, and the paper feed tray 7 is held at the lower limit position P3. 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, the space between the paper feed roller 2 and the uppermost surface of the paper 6 is secured within the range of 100 mm,
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 paper feed tray 7 are full or nearly full, and when a jam occurs near the paper feed roller 2, the paper feed tray 7 is once provided 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.

A first modification of the first embodiment will be described with reference to FIG. 15 (a modification of the invention according to claim 2).

This modified example 1 is different from the modified example 1 only in that the following functions are added to the control means 60. That is, the control means 60 controls the paper feed tray 7 to be detected when the paper feed tray 7 reaches the intermediate position P2 and the paper feed tray 7 is not detected by the intermediate detection sensor 4 or when the intermediate detection sensor 4 fails. When the lower limit position P3 is reached, it has a function of stopping the paper feed tray 7 at the lower limit position P3 by operating the tray elevating and lowering drive device 10 based on the signal from the lower limit detection sensor 5.

FIG. 15 is a flowchart showing the control of the tray elevating and lowering drive device 10 when the intermediate detection sensor 4 cannot detect the intermediate position P2 of the paper feed tray 7 due to a failure or the like. First, the flow of processing when the intermediate detection sensor 4 is normal will be described. Step S1
If it is determined that the paper feed tray 7 is descending, the process proceeds to step S2, and it is determined whether the paper feed tray 7 has reached the intermediate position P2. Paper feed tray 7 in step S2
When it is determined that the intermediate position P2 has reached the intermediate position P2, the process is coupled to J1, the process proceeds to step S4, the drive stop process of the tray lifting drive device 10 is executed in step S4, and the lowering operation of the paper feed tray 7 is completed. .

Next, the flow of processing when the intermediate detection sensor 4 is abnormal due to a failure or the like will be described. Step S1
If it is determined that the paper feed tray 7 is descending, the process proceeds to step S2, and it is determined whether the paper feed tray 7 has reached the intermediate position P2. Paper feed tray 7 in step S2
If it is determined that the paper feed tray 7 has not reached the intermediate position P2, the process proceeds to step 3 and it is determined whether the paper feed tray 7 has reached the lower limit position P3. If it is determined in step 3 that the paper feed tray 7 has reached the lower limit position P3 before reaching the intermediate position P2, the process proceeds to step 5 and the "intermediate detection sensor 4 abnormality flag" is turned on, and then step S4. In step S4, the drive stopping process of the tray elevating and lowering drive device 10 is executed, and the lowering operation of the paper feed tray 7 is completed.

Therefore, according to the first modification, there is an advantage that it is possible to prevent damage to the sheet feeding tray 7 and the tray elevating / lowering drive device 10 which would occur without stopping the lowering operation of the sheet feeding tray 7.

(Embodiment 2) Embodiment 2 of the invention according to claim 3 will be described with reference to FIGS.

Reference numeral 100 'indicates the sheet feeding device of the second embodiment. The paper feeding device 100 ′ is different from the paper feeding device 100 of the first embodiment in that it is detachably disposed near the lower part of the paper feeding roller 2 and can accommodate a plurality of papers 6 ′ and a paper feeding cassette 39. A paper feed cassette attaching / detaching mechanism 47 that detachably supports the paper feed cassette 39, and the paper 6 ′ stored in the paper feed cassette 39
And a cassette elevating / lowering drive device 40 as an elevating mechanism for exposing the sheet feeding position to the sheet feeding position. When the sheet feeding cassette 39 is not attached, the sheet 6 on the sheet feeding tray 7 is fed at the sheet feeding position. When mounted, the paper 6'is fed from the paper feed cassette 39 at the paper feed position.

The sheet feeding cassette 39, the sheet feeding cassette attaching / detaching mechanism 47, and the cassette elevating / lowering device 40 will be described below. The sheet feeding cassette 39 includes a substantially box-shaped sheet storage case 39b without an upper lid, a swingable sheet stacking plate 41 disposed in the front half of the bottom wall of the sheet storage case 39b, and a sheet stacking plate 41. An arm shaft 43 rotatably supported on the bottom wall of the lower paper storage case 39b, an arm shaft gear 44 integrally attached to one end of the arm shaft 43, and a loading device fixed to the arm shaft 43. It is mainly composed of a plate lifting arm 42.

Reference numeral 39a is an arm storage notch formed in the bottom wall of the paper storage case 39b for storing the stacking plate elevating arm 42 when it is not fed. 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. On both outer side walls of the paper feed cassette 39, cassette guides 48a,
A guide groove 49 is formed which engages with 48b and slides and guides the paper feed cassette 39 in the paper transport direction X and the opposite direction. The sheet stacking plate 41 has a swing shaft 4 whose base end is rotatably supported by the bottom wall of the sheet storage case 39b.
It is attached to 1s, and the free end swings in the up-and-down direction Z around the swing shaft 41s. Paper storage case 39
The thickness of b in the up-and-down direction Z is set to 50 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 engages with the free end of the sheet stacking plate 41. The paper feed cassette 39 is a so-called interrupt type cassette and is used when the paper size is to be changed 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 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 elevating and lowering drive device 40 includes a side plate 18b.
A lift arm drive motor 46 fixed to the inner wall of the upper part of the
An elevating arm drive gear 45 fixed to the output shaft end of the elevating arm drive motor 46 and selectively meshed when the paper cassette 39 is attached and detached, an arm shaft gear 44 disposed on the paper cassette 39 side, and an arm. Axis 43 and loading plate lifting arm 42
And a sheet stacking plate 41. The elevating arm drive motor 46 is a DC motor that can be driven to rotate clockwise and counterclockwise. The raising / lowering arm drive motor 46 is electrically connected to the control means 60 via an electric circuit (not shown), and is controlled by the control means 60 as described later.

Next, the paper feeding cassette 39 is loaded into the paper feeding device 10.
The operation when the sheet is attached to 0 ′ and is fed will be described. For example, referring to FIG. 3, 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 hits the paper feed roller 2. In the fully loaded state where they are in contact with each other, or in a state close to such a fully loaded state, secure a space required for mounting the sheet feeding cassette 39 between the sheet feeding roller 2 and the uppermost sheet 6. I can't. 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 down key 67
Is pressed for 3 seconds or more, and the paper feed tray 7 is lowered until the paper feed tray 7 is detected by the lower limit detection sensor 5 at the position reaching the lower limit position P3 through the control operation of the control means 60 as described above. Let At this time, the side fence pair 20a,
20b is pushed to the solid line position shown in FIG. 6 (or the virtual line position shown in FIGS. 1 and 2) by pushing down the side fence moving shaft lower 22 on the lower surface of the paper feed tray 7 against the tension spring. To descend. Thereby, the upper end surfaces of the pair of side fences 20a and 20b and the paper feed cassette 39
A necessary space that does not interfere with each other is secured between the bottom surface of the bottom wall of the paper storage case 39b and the bottom surface of the paper storage case 39b when it is mounted.
The distance between the intermediate detection sensor 4 and the lower limit detection sensor 5 is 100
Since the height is mm, a space between the paper feed roller 2 and the uppermost surface of the paper 6 is secured within a height (distance) range of 100 mm or more when the lowering operation of the paper feed tray 7 is completed (see FIG. 6). As described above, the thickness of the sheet feeding cassette 39 is 50 mm, and the sheet feeding cassette 3 is placed in the predetermined portion of the sheet feeding device 100 ′.
When 9 is mounted, the space between the paper feed roller 2 and the uppermost surface of the paper 6 is at least 5 in height (distance) in the vertical direction Z.
Since 0 mm is secured, it is possible to secure a sufficient space required for mounting the paper feed cassette 39. In this state, when the cover top 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 top 19 is closed.

In this way, when the print start key is pressed after the paper feed cassette 39 is mounted, a paper feed command signal is sent from the control means 60 to the cassette lift drive device 40, and the lift arm drive motor 46 is sent. 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, so that the stacking plate elevating arm 42 moves the paper stacking plate. The free end portion of 41 is lifted in the clockwise direction, and the uppermost sheet 6 ′ on the sheet stacking plate 41 occupies the sheet feeding position where it abuts the sheet feeding roller 2, that is, the upper limit position P <b> 1, and the sheet can be fed. Next, the normal rotation drive of the lifting arm drive 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 top 19 is opened and the paper feed cassette 39 is pulled out to the right in the drawing. Subsequent operations are the same as those in the first embodiment, and the description thereof will be 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.

A second modification of the first embodiment according to the invention of claim 4 will be described with reference to FIGS. 10 and 11. This modification 2 is different from the structure of the embodiment 1 in that the intermediate detection sensor 4
In place of the mounting position and the mounting method, the intermediate detection sensor 4 is different in that it has an intermediate detection means movement holding mechanism 70 that moves and holds the intermediate detection sensor 4 at an arbitrary position between the upper limit detection sensor 3 and the lower limit detection sensor 5. .

The intermediate detecting means moving and holding mechanism 70 includes a guide plate 71 fixed to the inner wall of the side plate 18a of the movable frame 18 in the ascending / descending direction Z, and the intermediate detecting sensor 4 at one end thereof.
Is attached, and the other end includes a sensor fixing plate 72 that is movably fixed to the guide plate 71 with a fixing screw 73. The guide plate 71 is set to a dimension longer than the distance between the upper limit detection sensor 3 and the lower limit detection sensor 5. The other end of the sensor fixing plate 72 has a guide plate 71.
It is bent so as to sandwich. The guide plate 71 and the sensor fixing plate 72 are made of, for example, a steel plate or a synthetic resin. Reference numeral 4a indicates a light emitting portion including an LED (light emitting diode) of the reflective optical sensor in the intermediate detection sensor 4, and reference numeral 4b indicates a light receiving portion including a phototransistor.

The intermediate detecting means moving and holding mechanism 70 has the above-described structure, moves the sensor fixing plate 72 to an arbitrary position along the guide plate 71, and tightens the fixing screw 73 at the position to detect the upper limit detecting sensor 3 And the lower limit detection sensor 5 can be moved and held at an arbitrary position.

Only the differences between the operation of the second modification and the first embodiment will be described. In the first embodiment, the position of the intermediate detection sensor 4 is 100 mm above the lower limit detection sensor 5 and the side plate 18 is located.
Although it was fixed to the inner wall of a, in the second modification, the position of the intermediate detection sensor 4 can be easily changed with respect to the lower limit detection sensor 5. Therefore, the intermediate detection sensor 4 of the first embodiment
If the intermediate detection sensor 4 is moved and fixed to the position close to the upper limit detection sensor 3 with respect to the position of
The distance between the intermediate detection sensor 4 and the intermediate detection sensor 4 is shortened, and the maximum number of sheets of paper 6 stacked on the paper feed tray 7 is reduced by the shortened distance. The movement distance of the paper feed tray 7 becomes shorter. On the other hand, if the intermediate detection sensor 4 is moved and fixed to a position close to the lower limit detection sensor 5, the upper limit detection sensor 3 and the intermediate detection sensor 4
And the maximum number of sheets of paper 6 stacked on the paper feed tray 7 increases by the lengthened distance. Therefore, according to the second modification, since the position of the intermediate detection sensor 4 can be easily changed with respect to the lower limit detection sensor 5, the lower limit detection sensor 5 and the intermediate detection sensor 4 can be easily changed.
There is an advantage that the maximum number of sheets of the sheets 6 stacked on the sheet feeding tray 7 can be changed within the moving range of the intermediate detection sensor 4 by changing the distance between the sheet feeding tray 7 and the sheet feeding tray 7. According to the second modification, the moving distance of the sheet feeding tray 7 from the intermediate position P to the sheet feeding position can be easily shortened, so that the sheet feeding tray 7 is returned from the intermediate position P to the sheet feeding position. There is an advantage that the paper feeding operation can be restarted in a short waiting time desired by the user by shortening the time.

Next, the thickness of the paper feed cassette 39 is 50 mm.
Corresponding to the case of 150 mm thicker than the above will be described.
In the first embodiment, the thickness of the paper feed cassette 39 is 50 mm, the distance between the intermediate detection sensor 4 and the lower limit detection sensor 5 is 100 mm, and the paper 6 loaded on the paper feed tray 7 is full. However, by lowering the sheet feeding tray 7 to the lower limit position P3 as described above, a space of 100 mm is created between the upper limit detection sensor 3 and the uppermost sheet 6 stacked on the sheet feeding tray 7, It was possible to attach a paper feed cassette 39 having a thickness of 50 mm to that portion. However, 150 mm thick paper feed cassette 3
When 9 is mounted, since there is only a space of 100 mm, it is impossible to mount such a paper feed cassette 39.

Therefore, in the second modification, as described above, since the position of the intermediate detection sensor 4 can be easily changed with respect to the lower limit detection sensor 5, the lower limit detection sensor 5 can be easily changed.
By moving and fixing the intermediate detection sensor 4 upward from a position of 150 mm or more by a distance of 150 mm or more, for example, 200 mm upward, even when the sheets 6 stacked on the paper feed tray 7 are full, as described above, Set the paper tray 7 to the lower limit position P3.
By lowering the sheet to the upper limit, the upper limit detection sensor 3 and the uppermost sheet 6 stacked on the sheet feed tray 7 are separated by 20
A space of 0 mm was created, and it was possible to mount a paper feed cassette 39 having a thickness of 150 mm at that portion.
That is, in the second modification, the paper feed cassette 3 is changed by changing the distance between the lower limit detection sensor 5 and the intermediate detection sensor 4.
Even if the thickness of 9 increases or decreases, the paper feed cassette 39 can be freely installed within the moving range of the intermediate detection sensor 4.

The intermediate detecting means moving and holding mechanism 70 is
Not limited to this, the intermediate detection sensor 4 is fixed to the timing belt, and the intermediate detection sensor 4 is moved and held by the intermediate detection means movement holding means including a pulley for driving the timing belt and a pulley drive motor. Good.

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.

The intermediate position P2 and the lower limit position P3 are determined based on the signals from the intermediate detection sensor 4 and the lower limit detection sensor 5.
As an auxiliary means for surely stopping the paper feed tray 7, for example, a braking means shown in FIG. 1 of Japanese Patent Laid-Open No. 1-187125, that is, the other end of the output shaft of the drive motor 11 is fixed. You may provide the structure which consists of the brake disc provided and the holding solenoid (both not shown) which press-connects a brake shoe to the said brake disc, and brakes it.

In each of the above-mentioned embodiments and modifications, the control means 60 is provided for switching the lower limit lowering position of the paper feed tray 7 according to the length of time the tray lowering key 67 is pressed, and the pressing time of the tray lowering key 67 is changed. If the time is less than 3 seconds, the paper feed tray 7 is lowered to the intermediate position P2, and if the pressing time of the tray lowering key 67 is 3 seconds or more, the paper feed tray 7 is lowered to the lower limit position P3. Needless to say, the time is not limited to the above-mentioned 3 seconds, and the pressing time may be other than the desired 3 seconds by the user or the like.

In the first and second embodiments, the paper feeding roller 2
Is disposed on the side of the main body frame 1F in the sheet feeding portion 58 of the stencil printing apparatus 1, but the present invention is not limited to this.
It may be arranged on the 100 'side.

The sheet feeding devices 100 of the first and second embodiments,
100 ′ is detachably arranged in the main body frame 1F of the stencil printing apparatus 1, but it is not limited to this, and it goes without saying that it may be fixedly arranged in the main body frame 1F of the stencil printing apparatus 1. In addition, the sheet feeding device 100 according to the first and second embodiments,
Needless to say, 100 'may be arranged as described above not only in the stencil printing apparatus 1 but also in an image forming apparatus such as a copying machine, a printing machine, a facsimile or a printer.

[0080]

As described above, according to the first aspect of the present invention, the control means is operated based on the signal from the lower limit detection means by operating the tray lowering setting means for a predetermined time or longer. Then, the paper feed tray elevating and lowering drive means is used to stop the paper feed tray at the lower limit position, so that one tray lowering setting means can be used for jam processing and paper replenishment without increasing the number of parts and increasing the cost. Paper feed tray for lowering the paper feed tray to the intermediate position and for jam handling when the paper feed tray reaches the intermediate position and the loaded sheets are full, or for mounting the paper feed cassette Can also be performed together with the operation of lowering the lower limit position.

According to the second aspect of the present invention, when the paper feed tray reaches the intermediate position, the intermediate detection means does not detect the paper feed tray and the paper feed tray reaches the lower limit position,
That is, when the intermediate detection means does not operate due to a failure or the like, the control means, based on the signal from the lower limit detection means,
Since the paper feed tray raising / lowering drive means is used to stop the paper feed tray at the lower limit position, it is possible to prevent the paper feed tray and the paper feed tray raising / lowering drive means from being destroyed without stopping the lowering operation of the paper feed tray. .

According to the third aspect of the invention, in addition to the effects of the first or second aspect, the interrupt type sheet feeding cassette can be attached and detached below the sheet feeding means by a simple mechanism.
When the paper feed cassette is not installed, the paper on the paper feed tray can be fed at the paper feed position, and when the paper feed cassette is installed, the paper can be fed from the paper feed cassette at the paper feed position. Further, since the same sheet feeding means can be used to selectively perform the sheet feeding operation from the sheet feeding cassette or the sheet feeding tray, the sheet conveying path from the sheet feeding means to the image forming unit of the image forming apparatus is changed. Since there is no need, the paper feed timing is constant, so that there is no need for a device or adjustment / control for fixing the paper feed timing by using a plurality of paper feeding means as in the related art. Particularly in a stencil printing machine, a slight difference in the paper feed timing has a great influence on the top-bottom deviation, so that the print quality can be improved. 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. Further, since a wasteful space above the sheet feeding means unlike the conventional apparatus is unnecessary, the image forming apparatus and / or the sheet feeding apparatus can be downsized.

According to the fourth aspect of the present invention, the intermediate detecting means moving and holding mechanism moves and holds the intermediate detecting means to an arbitrary position between the upper limit detecting means and the lower limit detecting means, so that the feeding is performed. Since it is possible to increase or decrease the maximum number of sheets to be stacked on the paper tray, it is possible to set a desired number of sheets to be stacked by the user or the like. Further, since the moving distance of the paper feed tray from the intermediate position to the paper feed position can be easily shortened, the return time of the paper feed tray from the intermediate position to the paper feed position can be shortened to shorten the time desired by the user. The paper feeding operation can be restarted during the waiting time. Further, even if the thickness of the paper feed cassette is changed, it can be attached and detached, so that the user or the like can freely use the paper feed cassettes having different thicknesses without worrying about the thickness. .

[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 first 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 first embodiment.

FIG. 4 is a front view showing the structure around the tray elevating and lowering drive device according to the first embodiment.

FIG. 5 is a perspective view showing a structure around a sheet feeding tray according to the first exemplary embodiment.

FIG. 6 is a vertical cross-sectional view showing a main part of a paper feeding device according to a second embodiment.

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

FIG. 8 is a partial vertical cross-sectional view showing, on an enlarged scale, the area around the cassette lifting drive device according to the second embodiment.

FIG. 9 is a block diagram showing a control configuration of the first and second embodiments.

FIG. 10 is a partial front view showing a main part of an intermediate detection means moving and holding mechanism of Modification 2;

FIG. 11 is a perspective view showing an intermediate detecting means moving and holding mechanism of Modification 2;

FIG. 12 is a flowchart for determining whether the lowering end position of the sheet feeding tray is the intermediate position or the lower limit position according to the pressing time of the tray lowering key.

FIG. 13 is a flowchart showing control of the tray elevating and lowering drive device by a lowering flag to a lower limit position.

FIG. 14 is a flow chart showing control of the tray lifting drive device by a lowering flag to an intermediate position.

FIG. 15 is a flowchart showing control of the tray lifting drive device of the first modification.

[Explanation of symbols]

1 Stencil printer as an image forming apparatus 2 Paper feeding roller as a paper feeding means 3 Upper limit detecting sensor as an upper limit detecting means 4 Intermediate detecting sensor as an intermediate detecting means 5 Lower limit detecting sensor as a lower limit detecting means 6, 6'paper 7 Paper Tray 10 Tray Elevating Drive Device as Paper Feed Tray Elevating Drive Unit 39 Paper Feed Cassette 40 Cassette Elevating Drive Device as Elevating Mechanism 47 Paper Feed Cassette Attaching / Detaching Mechanism 60 Control Unit 65 Timer 67 Tray Lowering as Tray Descent Setting Unit Keys 100, 100 'Paper feeder 70 Intermediate detection means moving and holding mechanism P1 Upper limit position P2 Intermediate position P3 Lower limit position

Claims (4)

[Claims] 1. A paper feed tray capable of moving up and down between an upper limit position where a plurality of sheets are stacked and raised to face a paper feed position and a lower limit position which is most lowered, and between the upper limit position and the lower limit position. A paper feed tray elevating and lowering drive means for moving the paper feed tray; a paper feed means for separating and feeding the uppermost sheets stacked on the paper feed tray one by one at the paper feed position; Between the lower limit detection means for detecting the lower limit position of the paper feed tray, the upper limit detection means for detecting the position of the uppermost sheet stacked on the paper feed tray, and between the upper limit detection means and the lower limit detection means. In order to stop the paper feed tray at a predetermined intermediate position of
An intermediate detection unit that detects the position of the paper feed tray; and a control unit that stops the paper feed tray at the intermediate position based on a signal from the intermediate detection unit.
In a sheet feeding device of an image forming apparatus that feeds the sheet on the sheet feeding tray at the sheet feeding position, a tray lowering setting unit that sets a lowering amount of the sheet feeding tray for a predetermined time is provided. By operating the tray lowering setting means for a predetermined time or more, the control means operates the paper feed tray elevating drive means based on the signal from the lower limit detection means to operate the paper feed tray. A sheet feeding device in an image forming apparatus, which is stopped at the lower limit position. 2. The sheet feeding device in the image forming apparatus according to claim 1, wherein when the sheet feeding tray reaches the intermediate position, the sheet feeding tray is not detected by the intermediate detecting unit, and the sheet feeding is performed. When the tray reaches the lower limit position, the control unit stops the sheet feed tray at the lower limit position by operating the sheet feed tray elevating drive unit based on the signal from the lower limit detection unit. A sheet feeding device in an image forming apparatus. 3. A sheet feeding device in the image forming apparatus according to claim 1, wherein the sheet feeding cassette is disposed near a lower portion of the sheet feeding means and can store a plurality of sheets, and the sheet feeding cassette. It has a paper feed cassette attachment / detachment mechanism that detachably supports, and an elevating mechanism that exposes the paper stored in the paper feed cassette to the paper feed position. A paper feeding device in an image forming apparatus, which feeds the paper from the paper feeding tray, and feeds the paper from the paper feeding cassette at the paper feeding position when the paper feeding cassette is mounted. 4. The sheet feeding device in the image forming apparatus according to claim 1, 2, or 3, wherein the intermediate detecting means is moved and held at an arbitrary position between the upper limit detecting means and the lower limit detecting means. A sheet feeding device in an image forming apparatus, characterized in that it has an intermediate detecting means moving and holding mechanism.