JPH03211122A - Paper supply device - Google Patents

Abstract

PURPOSE:To perform the supply of sheets by the appropriate quantity in the fixed position by detecting the uppermost surface height of sheets stacked on a baseplate at the time of the sheets being in the state to be supplied, and providing a means for controlling the descent of the baseplate so as to position the sheet uppermost face into the specified height. CONSTITUTION:A paper supply device is provided with a first detecting means SE6 for detecting sheets being in the state to be supplied and a second detecting means SE5 for detecting the uppermost face of the stacked sheets a baseplate 401. When the first detecting means SE6 detects the sheets being in the state to be supplied, a driving means is controlled by a control means on the basis of the detection signal of the second detecting means SE5 to lower the baseplate 401 so as to position the sheet uppermost face into the specified height.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a paper feeding device, particularly a large capacity paper feeding device used in an image forming apparatus such as an electrophotographic copying machine or a Bunonta.

BACKGROUND OF THE INVENTION In recent years, as copying speeds have increased and the number of copies has increased, paper feeding devices that feed sheets one by one to an image transfer section are required to have a larger capacity. Conventionally, this type of large-capacity paper feeding device
The base plate on which paper is loaded can be pulled out to the front side of the device and can be raised and lowered, and when replenishing paper, the base plate is lowered to the lowest position and pulled out to the front side.

However, in this method, if a capacity of about 10,000 sheets is to be secured, the slide mechanism for pulling out the base plate must be reinforced more than necessary, leading to an increase in the size and cost of the device. Further, when inserting and removing the base plate, a large amount of force is required from the operator, and there is a problem in that the alignment of the paper sheets becomes disordered due to the shock when inserting and removing the base plate. Furthermore, the lower limit position of the base plate is also deeper, and there is another problem in that it takes time to align and replenish the sheets.

The object of the present invention is to solve the above-mentioned problems, and to provide a paper feeding device suitable for a large capacity that does not require the base plate support mechanism to be made dog-shaped, is easy to handle, and can replenish paper with good alignment. It is about providing.

Means and Function for Solving the Problems In order to solve the above problems, the paper feeding device according to the present invention has the following features:
A base plate installed so that paper can be loaded and refilled from above,
A driving means for raising and lowering the base plate, a first detection means for detecting that paper is being replenished, and a second detection means for detecting the top surface of the paper completely loaded on the base plate. and when it is detected by the first detection means that the paper is being replenished, the driving means is controlled based on the detection signal of the second detection means, so that the uppermost surface of the paper is kept at a predetermined level. and control means for lowering the base plate so that the base plate is located at a height of .

The first detection means is, for example, a sensor for detecting the opening/closing of a lid member located at the top of the paper feeder, and paper is replenished by the operator opening the lid member and stacking the sheets on the base plate. . The height (uppermost surface) of the replenished paper is detected by the second detection means, and the base plate is lowered so that the uppermost surface of the replenished paper is maintained at a predetermined height. The amount by which the base plate is lowered is preferably such that a space is formed in which sheets can be replenished from above with good alignment. The base plate is lowered in steps according to the replenishment of an appropriate amount of paper, and a space is always formed above the fully replenished paper for appropriate replenishment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a paper feeding device according to the present invention will be described below with reference to the accompanying drawings.

Figure 1 shows the overall configuration of a copying machine, with an image forming section (1) on the left side and a paper transport section (2) extending from the center to the upper right side.
), a small/medium capacity paper feed unit (3) is placed in the center of the dome, a large capacity paper feed unit (4) according to the present invention is placed on the right side, and a sorter unit (5) is placed on the left side.

[Image Forming Unit, Figure 1 The image forming unit (1) has an automatic document feeder (50) (
An optical system (30) for a flash exposure method is arranged in the center, and a photoreceptor belt (10) is arranged in the lower part. The photoreceptor belt 4 (10) is a well-known type having a photoconductor layer on its surface, is supported endlessly by a plurality of rollers (11), and is driven to rotate in the direction of arrow (a). This photoreceptor belt (10
) around the electrostatic charge ~ (15〉), the developing device (16)
, transfer charger (19), paper separation charger (20)
), residual toner cleaner with fur brush (21
) and the residual charge eraser lamp (22) are incorrectly installed. The developing device (16) is of a magnetic brush type equipped with a developing sleeve (17), and the toner is stored in a tank (18).
will be replenished accordingly.

The exposure optical system (30) includes flash lamps (31), (31) that instantly illuminate the entire document table glass (29).
and a lens (32) that forms an image of reflected light from the original set on the original table glass (29) onto the photoreceptor belt (10) at a predetermined magnification.

A D F (50) is generally a document tray (51),
Paper feed belt (52), transport belt that can be driven in forward and reverse rotation (
56) and a pair of discharge rollers (58). The document (D) is set on the tray (51), and is fed from the bottom layer to the right based on the clockwise rotation of the paper feed belt (52), and is fed to the right side by the sorting roller pair (53) and the transport roller. The platen glass (2) is inserted through the pair (54) and (55).
9). Thereafter, the original is set at a predetermined position on the original platen glass (29) based on the clockwise rotation of the conveyor belt (56), and at that position, the lamp (31), (
31) undergoes flash exposure. The reflected light from the surface of the original passes through the lens (32) to the photoreceptor belt (10).
), and the original image is formed as an electrostatic latent image.

After exposure, the original is transferred to the original platen glass (
29) A pair of conveying rollers (57) are sent out from above to the left.
The discharge roller pair (58) is returned onto the tray (51) through the discharge roller pair (58).

On the other hand, for a document that has images on both sides, after the exposure of the first side is completed, the conveyance belt (56) is rotated counterclockwise and the document is returned to the pair of conveyance rollers (55) and (54). The document is turned over and sent from the path switching claw (59) onto the document table glass (29) again via a pair of conveying rollers (60). At this time, the document is set on the document table glass (29) with the second side facing down.

--ty, the photoreceptor belt (10> is rotated in the direction of the arrow (a) and uniformly charged by the charger (15), and -temporarily subjected to flash exposure from the optical system (30). Then , the photoreceptor belt (1o) is indicated by the arrow (
The electrostatic latent image formed on the surface of the electrostatic latent image that is rotationally driven in the direction a) is separated from the toner image by the developing device (16), and the toner image is completely conveyed as described in detail below due to the discharge of the transfer chuck 19). The image is transferred onto the paper that comes in.

The paper is separated from the photoreceptor belt (10) by the electric discharge from the separation charger (20) and its own strength, and is sent to the fixing device (70) through the conveyor belt (215).
Here, the toner is heated and fixed. The fixing device (7o) is composed of a heating roller (71) and a pressure roller (72), and a web winding type offset toner wiping device (73) is attached to the heating roller (71).

The photoreceptor belt (10) continues to rotate in the direction of arrow (a) after the transfer, residual toner is removed by a cleaner (21), residual charge is erased by an eraser lamp (22), and the image is prepared for the next copying.

[Paper transport unit and small and medium capacity paper feed unit, Fig. 1] The paper transport unit (2) is connected to each paper feed unit (310) of the small and medium capacity paper feed unit (3).
, (320), (330) or the large-capacity paper feeding unit (4>) to the image transfer unit, and a paper feeding and transporting unit that transports the paper fed from either of , (320), or (330) to the image transfer unit, and transports the paper after image fixation. It is divided into a discharge conveyance section and a discharge conveyance section.

The paper feed conveyance section consists of a conveyor belt (2
01), a plurality of conveyance rollers (202), conveyance roller pairs (206), (207), and a timing roller pair (20
8).

The small and medium capacity paper feeding section (3> is a small capacity paper feeding section (310) of a conventionally known swinging push-up plate type, a medium capacity paper feeding section of a conventionally known elevator type (320),
(330). Each paper feed section (310)
.

Paper (P) that cannot be accommodated in (320) or (330)
are paper feed belts (311), (321), (331
) is fed from the top layer based on the clockwise rotation of the separating roller pairs (312), (322),
(332), the sheets are sent out one by one to a paper feed conveyance path located in the vertical direction. The paper fed from the large-capacity paper feed unit (4) is transferred from the transport 8-roller pairs (221), (222), (223>) to the paper refeed belt (243) of the intermediate storage unit (240).
is sent to the upper part of the conveyor belt (201) through the conveyor belt (201). The paper fed as described above is fed by the timing roller pair (
At step 208), the photosensitive belt 10) is synchronized with the image formed on the photosensitive belt 10), and is conveyed to the transfer section.

On the other hand, the discharge conveyance section after the fixing device (70) is roughly composed of a paper reversing section (230), an intermediate storage unit (240), a discharge conveyance section (250), and a bridge conveyance section (260).

The paper reversing unit (230) is for reversing the front and back sides of the paper when executing the composite copying mode. When executing double-sided copying mode, the paper is guided by the right side of the path switching claw (231) and placed face-up on the pair of transport rollers (231).
32), leading to (233). When executing the composite copying mode, etc., the paper is guided under the path switching claw (231) and moved over the housing of the fixing device (70) by the transport rollers (234), (235), and the transport roller pair (237). Transported to the left. The trailing edge of the paper is the transport roller (234),
(235), the pair of conveyance rollers (237) is driven in the reverse direction, and the paper is reversed front to back and front and back, and the sheet is placed face down until it passes through the conveyance rollers (235) and (236).
from there to transport rollers (232) and (233).

The intermediate storage unit (240) temporarily stores the paper on which an image is formed on the first side when executing the double-sided copy mode or the composite copy mode, and then refeeds the paper that has been completely accommodated to the above-mentioned paper feed conveyance section. do. This intermediate storage unit (240)
are a pair of storage rollers (241), a base plate (2) that holds paper;
42), a paper refeed belt (243), a pair of sorting rollers (244), and a paper sorting plate (245). The base plate (242) can swing vertically using its rear end as a fulcrum, and is normally set in a position where its tip is raised as shown by the solid line in FIG. Conveyance roller (2
The paper conveyed from 32) and (233) is guided by a path switching claw (238) to either an intermediate storage unit (240) or a discharge conveyance section (250) to be described later. The sheets guided to the intermediate storage unit (240) are stacked and stored on the base plate (242) from the storage roller pair (241). When the double-sided copy mode is executed, the paper is stored with the copied first side facing upward, and when the composite copy mode is executed, the paper reversed by the paper reversing section (230) is stored with the copied first side facing downward. be accommodated. When a predetermined number of sheets of paper have been stored, the base plate (242) swings downward to the same height as the top surface of the paper refeeding belt (243), and the paper refeeding belt (243) is rotated based on the paper refeed signal. rotates counterclockwise, and the pair of rollers (244
) to the upper end of the conveyor belt (201).

The discharge conveyance section (250) includes a conveyor belt (251) that is rotationally driven in a clockwise direction, a conveyor roller (252), (
253).

(254), a path switching claw (255), and a pair of discharge rollers (256). When executing single-sided copy mode and copying by refeeding paper in duplex/composite copy mode,
The paper is guided by the upper surface of the path switching claw (238) and transported on the transport belt (251). Then, it is guided to either the bridge transport section (260) or the tray (257) by the path switching claw (255).

The tray (257) is provided on the upper inclined part of the main body frame, and the lower and middle parts are provided with regulation levers (258), (2
59) is installed movably on the tray (257).

The paper guided on the left side of the path switching claw (255) is discharged onto the tray (257) from the discharge roller pair <256>. When small-sized paper is ejected, the regulation lever (258) projects onto the tray (257) and regulates the leading edge of the small-sized paper to be ejected. When large size paper is ejected, the regulation lever (258)
The dog-sized paper is stored inside the bottom regulation lever (
259). Note that the tray (257) can also be used as a temporary storage location for documents.

The bridge conveyance section (260) is connected to the discharge conveyance section (250).
The tray is for guiding the paper that has been passed to the sorter unit (5), and is installed at the top of the large-capacity paper feed unit (4), and is supported by a roller (261) and driven to rotate clockwise. conveyor belt (262), conveyor roller (2
63), the details of which will be described later together with the sheet feeding unit (4).

The sorter unit (5>) has 30 bins (501) stacked vertically at regular intervals, and a deflection claw (502) and a pair of discharge rollers (503) are installed on the entrance side of each bin (501). The paper conveyed from the bridge conveyance section (260) is conveyed downward through the vertical conveyance section (504), and during the conveyance, the course is sequentially changed to the horizontal direction by the deflection claw (502), and then the sheet is transferred to the discharge roller pair (503). ) to predetermined bins (501).

[Large capacity paper feed unit, Figures 2 to 7 The large capacity paper feed unit (4) can accommodate 10,000 sheets of paper on the base plate (401). It is said that it can be raised and lowered in a fixed position.

First, the elevating drive mechanism will be explained with reference to FIG. The driving source for lifting and lowering is a stepping motor (M) that can be driven in forward and reverse directions, and a worm gear (411) installed on its output shaft.
meshes with a worm wheel (412) fixed to one end of the drive shaft (413). Sprockets (415), (416), (417), (41) fixed to drive shafts (413), (414) installed parallel to each other.
8) and each sprocket (419
), (420).

A roller chain (
423).

(424), (425), and (426) are stretched endlessly, and this roller chain (423) to (426)
The base plate (401) is supported by the four corners. Also, a drive shaft (413).

(414) is a sprocket (427) fixed to the end;
By extending a roller chain (429) between the rollers (428), they can be rotated synchronously in the same direction.

When the stepping motor (M>) is driven to rotate normally in the direction of arrow (b), the drive shaft <413) is driven to rotate in the direction of arrow (b) via gears (411) and (412), and at the same time, the roller chain ( 429), another drive shaft (414) is also driven in the direction of arrow (b). Also, the four roller chains (423) to (426) are also indicated by the arrow (b).
direction, and the base plate (401) rises.

When the stepping motor (M) is reversely driven in the direction opposite to the direction of the arrow (b), each member rotates in the opposite direction, and the base plate (
401) will fall.

A rotating disk (430) is fixed to the end of the drive shaft (413), and a photosensor (SEI) whose optical axis coincides with slits formed at equal intervals around the circumference of the disk (430)
), the rotational speed of the drive shaft (413), that is, the base plate (401
') is detected. The base plate (401) includes the frame (430) and (44) shown in FIGS. 3, 4, and 5.
0>.

It is guided from all sides by (451) and (452) and can be raised and lowered between the upper limit position (when the paper is empty) shown by the solid line in FIG. 4 and the bottom of the unit (4).

The sensor (S) indicates that the base plate (401) has descended to the lower limit position.
E2) is detected by the detection signal from E2). Further, a reflective photosensor (SE3) is installed on the base plate (401) to detect the presence or absence of paper (P).

At the top of the frame (430) is a paper feed belt unit (4
35) is installed, and this unit (435) is equipped with a roller (
437), a paper feed belt (436) supported by (437) and driven to rotate clockwise, and a vacuum f-near <438> for sucking the top layer of paper onto the surface of the paper feed belt (436>). It is composed of.

The base plate (401) is held by the elevating drive mechanism so that the top surface of the paper (P) loaded thereon is maintained at the paper feeding position indicated by (A> in FIG. 3) (the control thereof will be described later). The top layer of paper is fed as the paper feed belt (436) rotates clockwise.An air duct (433) with a nozzle (434> facing inward) is installed at the top of the front frame (430). and the nozzle (43
From 4), air is blown onto the front edge of the paper at the top to separate the fed sheets one by one.

The paper (P) on the base plate (401) is attached to the frame (430).
).

(440), (451), and (452) on all sides, and the rear end of the upper sheet is also regulated by a regulating plate (441). As shown in FIG. 5, this regulating plate (441) is attached to a frame (451) via a support shaft (442) fixed to its lower end.

(452) is rotatably supported. Support shaft (442
The lever (443) fixed to one end of the solenoid (
SL) plunger (452) and one end of the frame (45
The tension coil spring (4) fixed to the pin (453) of 1)
54). The regulation plate (441) has a spring (
454) is constantly biased in the direction of arrow (c) and when the solenoid (SL') is turned off, the lever (443)
The upper part of the frame (451') is the stopper pin (455).
), it is set flush with the back frame (440). When the solenoid (SL) is turned on, the regulation plate (441) rotates in the direction of the arrow (c')' (see Fig. 4), the base plate (401), and the trailing edge of the paper stacked thereon. Evacuate from the position to open a space for paper replenishment. Further, when the solenoid (SL) is turned off, it rotates in the direction of arrow (c) to press the rear end of the paper and align the paper.

Furthermore, a movable plate (445> is attached to the regulation plate (441>) via a bracket (447). The movable plate (445) has pins (446) fixed to its side, (
466) is the long hole (447a) of the bracket (447)
, (447a) and a protrusion (445) provided on the top.
a) can be moved up and down while positioned directly above the paper (P). Also, the upper pin (446) and bracket (447)
) A tension coil spring (449) is installed between the pin (448) fixed to the movable plate (445>), and the movable plate (445> is always set downward by this spring (449). (P) rises together with the base plate (401'), and when the top surface of the paper (P) comes into contact with the protrusion (445a), the movable plate (445) moves upward slightly.This upward movement is movable. The bottom of the plate (445) is the photosensor (SE
4) by releasing the optical axis of the photosensor (S
It is detected by the signal emitted from E4). This detection signal stops the normal rotation of the stepping motor (M), and the top surface of the paper (P) is set at the paper feeding position (A).

In addition, the frames (451') and (452) are equipped with light emitting diodes (451') and (452) whose optical axes are aligned, as shown in FIGS. 5 and 6.
LED5), (LED6) and photosensor (SE5)
, (SEfli) are installed in two stages to detect the presence or absence of paper. The position (B) detected by the photosensor (SE6) is a reference position when replenishing paper onto the base plate (401). The position (C) detected by the photosensor (SE5) is the upper limit position when replenishing paper.

A lamp (Pl) indicating that paper replenishment processing is completed and a lamp (P2) indicating excessive replenishment are installed inside the upper part of the rear frame (452).

Regarding excess replenishment, an excess line (453> is drawn on the frame (452) directly below the upper limit position (C) detected by the photosensor (SE5), so that the operator can visually confirm the upper limit of replenishment. There is.

Next, the configurations of the paper feeding system and conveyance system will be explained.

As shown in FIGS. 6 and 7, the drive roller (261>).

The support shafts (264) and (439) of (437) are connected to the unit drive unit (470) by the driving force transmission unit (471) and (4
72). Paper feed belt unit (
435) Tsubakyumuro (438> is a vacuum source (4)
73) via a duct (474). The conveyance rollers (263) are rotatably mounted on the upper frame (481), and are connected to the drive roller (261), paper feed belt unit (435>, transmission section (471), (47)
2) and the duct (474) are attached to the middle frame (483). The middle frame (483) is installed on the main body frame (490) of the paper feed unit (4) via a support shaft (484) so as to be openable upward (see FIG. 7). Further, the upper frame (481) is installed on the middle frame (483) via a support shaft (482) so as to be openable upward. The tips of the frames (481) and (483) are separated into gripping parts (481a) and (483a).

The middle frame (483) is opened when a paper jam is cleared in the paper feed section and when paper is replenished, and the upper frame (481) is opened when a paper jam is disposed of in the bridge transport section (260). Opening of the middle frame (483) is detected by a detection signal from a sensor (SE7) that is turned on and off by a magnet (485) fixed to the middle frame (483).

Also, a unit drive section (470) and a drive transmission section (471)
>.

(472), vacuum source (473) and duct (47
4) are configured to be able to be automatically connected to and separated from each other, and are disconnected when the middle frame (483) is opened and reconnected when closed.

[Control Circuit, FIG. 8] FIG. 8 shows a main part of the control circuit of the copying apparatus having the above configuration.

Control is performed mainly by a microcomputer (600), and the computer (600) is equipped with a sensor (SEL).
) to (SE7) are input, and drive signals are output to the power supply circuits of the stepping motor (M) and the solenoid (SL).

Here, the signals output from the various sensors (SEI) to (SE7) will be explained.

Sensor (SE3): When the reflected light from the paper is not fully input, it outputs an empty signal (Sl) indicating that there is no paper on the base plate (401).

Sensor (SE4): When the light is blocked by the lower part of the movable plate (445) and no light is received, the top surface of the paper is at the normal paper feeding position (
A) outputs a paper feeding position lowering signal (S2) indicating that the paper feeding position is lower than A).

Sensor (SE5): When the light is blocked by the paper and no light is received, it outputs a paper excess signal (S3) indicating that the top surface of the supplied paper is higher than the upper limit position (C).

Sensor (SE6): When the light is blocked by the paper and no light is received, it outputs a replenishment position upper limit signal (S4) indicating that the top surface of the paper is higher than the replenishment position (B).

Sensor (SE7): Outputs a unit close signal (S5) when the middle frame (483) is closed and detects the magnet (485).

Sensor (SE2): The base plate (401) is the unit (4
) When it is detected that the base plate has descended to the lower limit position within ), a base plate lower limit signal (S6) is output.

The sensor (SEL) outputs a rotation pulse signal of the disc (430). This rotation pulse signal is counted when the base plate (401) is in a rising motion, and is used to calculate the remaining amount of paper on the base plate (401) based on this count value. Note that the calculated remaining amount of paper is displayed on an operation panel (not shown).

[Control procedure, Fig. 9 et seq.] Next, we will discuss the operation of the copying machine, especially the large-capacity paper feed unit (4).
The operation at the time of paper replenishment will be explained with reference to the flowcharts in FIG. 9 and subsequent figures.

FIG. 9 shows the main routine of the microcomputer (600).

When the power is turned on and the program starts, the RA, M, and each control element are returned to their initial states in step (Sl).
An internal timer is started in step (S2). This internal timer is built into the microcomputer (600), and is set to a predetermined value in advance. It defines the length of one main routine and serves as the standard for the various timers that appear in the following subroutines. Become.

In steps (53), (separate), (55), each sensor (
SE3).

(SE7), signal (51) from (SE5), (S
5), (53) on.

It is determined that it is off, and the process proceeds to either step (56) or (59). Step (S6) is a normal subroutine for driving the base plate (401) up and down during a copy operation or during copy standby. Step (S9) is a subroutine for driving the base plate (401) up and down when replenishing paper.

In step (S3), the paper empty signal (Sl) from the sensor (SE3) is checked, in step (S4), the unit close signal (S5) from the sensor (SE7) is checked; ) Check the excess paper signal (S3) from Signal (51)
, if (53) is off and the signal (S5> is on), then
The inside of the large capacity paper feed unit (4) is normal and the step (
After calling the subroutine of step S6), step (S7
) sets the state counter to "1". This state counter is used in the subroutine of step (S9), which will be detailed below. Next, in step (S8), a copy operation subroutine is called, and in step (511)
) calls subroutines for other processing operations. Is the paper empty signal (Sl) on or the unit close signal (
If S5) is off or the excess paper signal (S3) is on, a subroutine for paper replenishment is called in step (S9), an instruction is given to prohibit the copying operation in step (510), and the process is executed in step (510). 511) is called. Finally, in step (S12), the process waits for the internal timer to end and returns to step (S2).

FIG. 10 shows a normal subroutine for driving the base plate up and down, which is executed in step (S6) of the main routine.

Here, in step (5601) the solenoid (SL>
Turn off. As a result, the regulating plate (441) is held vertically and regulates the trailing edge of the paper. Then step (
5602), it is determined whether the paper feed position lowering signal (S2) output from the sensor (SE4) is on. Signal (S2
) is output when the top surface of the paper is lower than the paper feeding position (A) and the lower part of the movable plate (445) has entered the optical axis of the sensor. Therefore, if the signal (S2) is on, the stepping motor (M) is driven in the normal rotation in step (5603) to raise the base plate (401'').

The base plate (401> rises with the paper and the top surface of the paper reaches the paper feeding position (A>), and the upward movement of the movable plate (445) causes the signal (
When S2) is turned off, the stepping motor (M) is turned off in step (5604).

FIGS. 11a, iiib, and 11c show subroutines for paper replenishment executed in step (S9) of the main routine.

Here, first, in step (5901), the count value of the state counter is checked, and the following steps are processed according to this count value.

When the current value of the state counter is “1”,
In step (5911), it is determined whether the base plate lower limit signal (S6) output from the sensor (SE2) is off. If the base plate (401) has not descended to the lower limit position in the unit (4) [YES in step (5911)], the supply position rise signal (S4) output from the sensor (SE6) in step (5912) Determine whether it is on or not. signal(
S4) is turned on when the top surface of the paper is at a position higher than the replenishment position (B). Therefore, if the signal (S4) is on, the state counter is set to 2" in step (5913), and the step (592) is to lower the base plate (401).
1) Head below. If the signal (S4) is off and the top surface of the paper is down to the replenishment position (B), step (591) is executed.
4) Turn on the solenoid (SL), and step (591)
In step 5), set the state counter to "4".

When the solenoid (SL) is turned on, the regulation plate (441) rotates in the direction of arrow (C') and retreats from the trailing edge of the paper (see FIG. 4). As a result, some space is formed behind the paper or the base plate (401), and it becomes possible to perform paper replenishment processing with good alignment. In this state, paper is replenished. On the other hand, if the base plate lower limit signal (S6) is on [No in step (5911)], the base plate (401
) has descended to the lower limit position, so step (591
Step 6) sets the state counter to "6" and checks the topmost position of the stacked sheets (596).
1) Head below.

When the state counter's current position is "2", the solenoid (SL> is turned off in step (5921') to return the regulation plate (441) to paper trailing edge regulation, and the stepping motor (M) is turned off in step (5922). ) is reversely driven, and the state counter is set to "3" in step (5923).The base plate (401) then starts to descend.

When the state counter value is "3'", that is, when the base plate (401) starts to descend, step (5) is executed.
In step 931), it is determined whether or not the base plate lower limit signal (S6) is off, and in step (5932), it is determined whether or not the supply position rise signal (s4) is on. If both are YES, that is, the base plate (401) is not at the lower limit position and the base plate (401) is not at the lower limit position, and the base plate (401) is not at the lower limit position.
01) If the uppermost surface of the paper is higher than the replenishment position (B), leave the state counter at "3'" and repeat the steps here. When the top surface of the paper descends to the replenishment position (B), [NO in step (5932)
], the stepping motor (M>
Turn off the solenoid (SL) in step (5934).
is turned on, and the state counter is set to "4" in step (5935). That is, the base plate (401) stops descending when the top surface of the paper reaches the replenishment position (B), and the regulation plate (441) moves in the direction of the arrow (C') toward the base plate (401) and the trailing edge of the paper. Evacuate from. In this state, paper is replenished.

On the other hand, if the bed plate lower limit signal (S6) is turned on, [step (
5931), the base plate (401) has descended to the lower limit position, so the stepping motor (M) is turned off in step (5936), and the state counter 27 is set to "6" in step (5937).

When the current value of the state counter is 4, that is,
When replenishing paper, step (5941)
After confirming that the supply position rise signal (S4) is turned on and paper has been supplied, the timer (T) is started in step (S942), and the state counter is set to "5" in step (5934). . The timer (T) is preset to the time required for the operator to align the newly supplied sheets to their regular positions plus a slight margin.

When the count value of the state counter is "5", when it is confirmed in step (5951) that the timer (T) has finished counting, the timer (T) is started in step (5952).
Reset. Next, the solenoid (SL) is turned off in step (5953), the stepping motor (M> is driven in reverse in step (5954), and step (595) is turned off.
In step 5), set the state counter to "3".

That is, when the count of the timer (T) ends, it is determined that the replenishment and alignment of the sheets are completed, and the regulation plate (441) is returned to the paper trailing edge regulation position, and the base plate (401) is lowered again. Thereafter, the process moves to step (5931) and the subsequent steps to continue the paper replenishment process.

When the current value of the state counter is 6, that is,
When the base plate (401) is located at the lower limit detected by the sensor (SE2), in step (5961) the sensor (SE5)
It is determined whether or not the excess paper signal (S3) output from the printer is off. If the signal (S3) is off, the top surface of the paper has not exceeded the upper limit position (C) and the supply amount is appropriate, so the solenoid (SL) is activated in step (S962).
) is turned off to set the regulation plate (441) to the vertical regulation position, effectively prohibiting further paper replenishment. continue,
In step (5963), the replenishment completion indicator lamp (Pl) is turned on, and in step (5964), the paper excess indicator lamp (Pl) is turned on.
P2) is turned off or maintained in the off state. Further, in step (5965), the excess paper warning on the operation panel is canceled or maintained in the canceled state.

On the other hand, if the excess paper signal (S3) is on [No in step (5961)], the top surface of the paper is at the upper limit position (C).
Therefore, in step (5966), the solenoid (SL) is turned on to retract the regulation plate (441) from the regulation position, making it easy to take out the excess paper. Next, in step (5967), the replenishment completion display lamp (Pl
) is turned off or remains off. Furthermore, the step (
5968) turns on the excess paper display lamp (P2), and in step (S969) instructs an excess paper warning on the operation panel.

According to the above control procedure, when the inner frame (483) of the large-capacity paper feed unit (4) is opened, it is determined that the paper is ready to be replenished, and the top surface of the base plate (401) or the top surface of the paper is replenished. Set it to position (B). Then, each time the sheets are stacked up to the upper limit position (C), the base plate (401) is lowered to set the top surface of the sheets at the replenishment position (B). The operator only needs to replenish paper in appropriate amounts from above in accordance with the stepwise lowering movement of the base plate (401), and it becomes possible to replenish paper in an orderly manner and efficiently. In addition, there is no need to take the base plate (401) in and out of the front side of the device.
There is no fear that the paper alignment will be disturbed when loading and unloading.

Furthermore, when replenishing paper, if the sensor (SE5) detects that an appropriate amount of paper has been replenished, a timer (T) lowers the base plate (401) after a preset time elapses. This allows the operator to adjust the paper alignment with plenty of time, resulting in a good replenishment tempo.

In addition, the regulation plate (441) is rotatably provided using a solenoid (SL>) and a return spring (454), and is evacuated from the paper trailing edge regulation position when waiting for replenishment, and returns to the regulation position when an appropriate amount of paper is replenished. As a result, a work space for replenishment can be secured, and the replenished paper is automatically aligned.The regulation plate (441) is not placed in a position opposite to the trailing edge of the paper, but in another position. It may be installed in

Furthermore, when the base plate (□401) descends to the lower limit position,
If there is too much paper loaded, a warning is issued to that effect, allowing the operator to easily discover the problem and prevent paper feeding problems.

Effects of the Invention As is clear from the above explanation, according to the present invention, when the paper is being replenished, the height of the top surface of the paper stacked on the base plate is detected, and the height of the top surface of the paper is determined to be 31. - Since the base plate is controlled to descend so that it is positioned at a predetermined height, it is possible to replenish paper in appropriate amounts at a fixed position (at a high height), and the alignment is also good, making it a paper feeder suitable for large capacity. can be obtained. Furthermore, despite the large capacity, there is no need for a pull-out mechanism such as a rail, and it is possible to avoid problems such as the increase in the size of the device and the problems in which the sheets become misaligned due to the impact of loading and unloading.

[Brief explanation of drawings]

The drawings show an embodiment of the paper feeding device according to the present invention, FIG. 1 is an overall configuration diagram of a copying apparatus including an image forming section and a sorter unit, FIG. The figure is a configuration diagram showing the upper part of the paper feed unit, Figure 4 is an overall configuration diagram of the paper feed unit, Figure 5 is a perspective view showing the upper part of the paper feed unit, and Figure 6 is a side view of the upper part of the paper feed unit. 7 is a sectional view of the paper feed unit viewed from the front with the upper part open. FIG. 8 is a block diagram of the control circuit, and FIGS. 9, 10, 11a, and 11b and 11C are flowcharts showing the control procedure. (1)...Image forming section, (4)...Large capacity paper feed unit, 32- (401>...base plate, (483>middle frame, (60
0)...Microcomputer, (M)...Stepping motor for lifting/lowering drive, (SE5), (SE6)
...Sensor for detecting the top surface of paper, (SE7)...Sensor for detecting unit opening/closing, (S3)...Excess paper signal, (
S4)...Replenishment position rise signal, (S5>...Unit close signal.

Claims (1)

[Scope of Claims] 1. A base plate installed to be able to load and replenish paper from above; a drive means for raising and lowering the base plate; the first detection means; the second detection means for detecting the uppermost surface of the paper stacked on the base plate; and when the first detection means detects that the paper is in a state of being replenished. , a control means for controlling the drive means based on a detection signal from the second detection means and lowering the base plate so that the uppermost surface of the sheet is positioned at a predetermined height. paper feed device.