JP2607954B2 - Sheet feeding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a sheet feeding apparatus for feeding a plurality of stacked sheets by changing a feeding mode between a normal sheet and a thick sheet.

<Related Art> In a recording apparatus such as a printer or a copying machine, or a document reading apparatus, a feeding apparatus (separating and feeding a sheet from a plurality of stacked sheets (recording paper, document, etc.) one by one) is used. Many use a so-called cut sheet feeder).

There are various types of sheet separating mechanisms of the feeding device, and a representative one of them uses a separating claw. This is, as shown in FIG.
Separation pawls on both sides of the front end in the feeding direction of the sheet 51 stacked on 50
The uppermost sheet is pressed against the feed roller 54 by pressing the stacking plate 50 with the pressure contact spring 53, and when the feed roller 54 is rotated in the direction of the arrow, a thrust acts on the sheet 51. On the other hand, since the leading ends of both sides of the stacking sheet 51 are pressed by the separating claws 52, one of the uppermost layers is separated as shown in FIG.
Create a loop between 52 and feed roller 54.

When the feeding roller 54 is further rotated, the sheet 51 rides over the separation claw 52 by the restoring force and is sent to the conveying roller 55, and the leading end is abutted against the conveying roller 55 as shown in FIG. A loop was formed between the roller 54 and the transport roller 55.

<Problems to be Solved by the Invention> In the conventional feeding method, sheets are fed by the same operation without discrimination of plain paper and postcards.

However, since the sheet thickness is different between plain paper and postcard, in the same feeding operation, the sheet separation, loop amount and cue amount are different due to the difference in the sheet thickness, so that proper feeding may not be performed.

Further, in the conventional example, the sheet 51 is separated from the separation claw 52,
Since the feed roller 54 was continuously rotated until a loop was formed by abutting against the transport roller 55, the sheet 51
Immediately after the separation by 52, the sheet abutted on the transport roller 55 in an unstable state. For this reason, the formation of the loop shown in FIG. 6 (C) becomes unstable, and this may cause wrinkles or skew.

An object of the present invention is to solve the above-mentioned conventional problems and to change a feeding mode between a normal sheet and a thick sheet to perform appropriate sheet feeding regardless of the sheet thickness and to feed a normal sheet. In this case, a sheet feeding device capable of forming a stable loop on the separated sheet is provided.

<Means for Solving the Problems> Separating claws for holding both front end portions of a sheet on the uppermost layer of a plurality of stacked sheets, and feeding for applying a feeding force to the sheet on the uppermost layer Means, conveying means for conveying sheets separated and fed one by one by the cooperation of the separating claw and feeding means, and determining whether the stacked sheets are ordinary sheets or thick sheets. A feeding means for feeding a normal sheet selected based on a result of the determining means, after removing a sheet on the uppermost layer from the separation claw, and then after a predetermined waiting time, to a conveying means. In order to feed a thick sheet and a normal sheet feeding mode for driving the feeding means, the uppermost sheet is removed from the separation claw, and then fed to the conveying means without passing the waiting time. Drive the feeding means And a thick sheet feeding mode.

<Operation> In the above-mentioned means, the sheet feeding mode of the feeding means changes depending on whether the sheet is a normal sheet or a thick sheet. Therefore, the sheets are accurately fed in a state suitable for each sheet.

When a normal sheet is fed, the sheet is separated for a predetermined time after the sheet is separated by the separation claw, and then the sheet is fed to the conveying means. As described above, the sheet in the unstable state immediately after the separation is temporarily stopped, and is fed to the conveying unit after the sheet is in the stable state, so that the sheet forms a stable loop.

<Embodiment> Next, an embodiment of a recording apparatus to which the above-described means is applied will be described with reference to FIGS.

1 (A) to 1 (D) are explanatory diagrams of a sheet feeding state by a sheet feeding device according to the present embodiment, FIG. 2 is a configuration explanatory diagram of a sheet feeding device, and FIG. FIG. 2 is an explanatory diagram of a configuration of a recording device using a sheet feeding device.

In this sheet feeding apparatus A, as shown in FIGS. 2 and 3, the frame 1 is divided into a left half 1a and a right half 1b, and these are moved along the axis 2 so as to extend in the full width direction. It is possible to adjust.

A large number of recording sheets 4 are stacked on a mounting plate 3 inside the frame 1, and the mounting plate 3 is pressed by a pressing spring 5 toward a feed roller 6 fixed to the shaft 2. The uppermost layer of the recording sheet 4 is configured to be pressed against the feeding roller 6.

Side guides 7 are provided on outer side walls of the left and right frames 1a and 1b to guide the side edges of the recording sheet 4, respectively.
Further, separation claws 8 for separating one recording sheet 4 of the uppermost layer at the time of sheet feeding are provided on both sides of the front end. Therefore, when the feed roller 6 is rotated in the direction of arrow a by the feed motor 6a, a thrust is applied to the uppermost recording sheet 4 by the frictional force of the roller 6, but the recording sheet 4
Is stopped by hitting the separation claw 8 and the uppermost recording sheet 4 is separated and fed so as to form a loop.

A transport roller 9 serving as a transport unit is disposed in front of the separation claw 8 in the sheet feeding direction, and the recording sheet 4 separated by the separation claw 8 is stopped for a predetermined time and then transferred to the transport roller 9.
And is conveyed by the rollers 9.

On the recording sheet 4 separated and fed by the sheet feeding device A, a predetermined image is recorded by a recording device B as shown in FIG. The configuration of the recording device B will be described.
Pinch rollers 10 a and 10 b are in pressure contact with the transport roller 9, and are configured to rotate following the rotation of the transport roller 9. Accordingly, the recording sheet 4 sandwiched between the transport roller 9 and the pinch roller 10a is transported by the transport roller 9 rotating in the direction of the arrow b by the transport motor 9a, and a predetermined recording is recorded by the recording means 11.

In the present embodiment, the recording unit 11 uses an ink jet system.An ink jet recording head 11c is mounted on a carriage 11b movable by a carriage motor (not shown) along a guide shaft 11a. nozzle 11c ₁ are arranged in tandem. Therefore, in synchronization with the movement of the carriage 11b discharge in accordance with the ink of the image signal from the ink nozzles 11c _1, it is possible to record predetermined image on the recording sheet 4. Reference numeral 11d denotes a plate-like platen that has a built-in heater and is adjusted to a temperature of, for example, about 60 ° C., and has a function of drying the ink discharged on the recording sheet 4.

The recording sheet 4 recorded by the recording means 11 is discharged to the stacker 13 by a discharge roller 12a and a spur roller 12b which is pressed against the spur roller 12b and driven to rotate.

The sheet feeding device A has a sheet presence / absence sensor for detecting whether or not the recording sheet 4 is on the placing plate 3.
A sheet detection sensor 15 for detecting the leading end of the recording sheet 4 is disposed at a predetermined position between the pinch rollers 10a and 10b. In this embodiment, a size detection sensor 16 for detecting the position of the side guide 7 to detect the sheet size is provided. The size detection sensor 16 has a function of detecting the sheet thickness in the present embodiment, and detects, for example, a difference between a normal sheet and a thick sheet (postcard or the like) as a size difference.

Here, a control system for driving and controlling the feeding device A and the recording device B is configured as shown in the block diagram of FIG.

Specifically, for example, a CPU 17a such as a microprocessor,
A ROM 17b storing a control program and various data to be operated according to the procedure shown in the flowchart of FIG.
And a control unit 17 which is used as a work area for the CPU 17a and includes a RAM 17c for temporarily storing various data and the like.
The control unit 17 includes an operation panel 19 having a recording start switch and the like via an interface 18, a sheet presence sensor 14, a sheet detection sensor 15, and a size detection sensor 1.
6. Input a signal from the image signal input device 20 or the like. In addition, a signal is output from the control unit 17 to the feed motor 6a, the conveyance motor 9a, the motor driver 22 for driving the carriage motor 21, and the head driver 23 for driving the recording head 11c via the interface 19. Make up.

Next, a procedure for feeding the recording sheet 4 by the feeding device A will be described. In the present embodiment, an example will be described in which a postcard is fed as a thick sheet, and plain paper of, for example, A4 size having a size different from that of the postcard is fed as a normal sheet.

As shown in the flowchart of FIG. 5, when the recording start switch is turned on, it is detected in step S1 whether or not the recording sheet 4 is on the mounting plate 3 by the sheet presence / absence sensor 14, and the recording sheet 4 In some cases, i.e. sensor 14
When is turned on, the process proceeds to step S2, where the size detection sensor 16 determines whether the recording sheet 4 to be fed is plain paper or postcard. If the recording sheet 4 is plain paper, the sheet is fed according to the normal sheet feeding mode.

That is, the process proceeds to step S3, and the sheet type variable H is set to “0”.
Is set, and the process proceeds to step S4 to drive the feed motor 6a by a predetermined amount (350 steps in the present embodiment) to drive the recording sheet 4a.
Is separated by only one sheet. The driving amount of the feed motor 6a is:
After the feed roller 6 starts rotating (the state shown in FIG. 1A), the uppermost recording sheet 4 is separated from the separation claw 8 and the feed roller 6.
A loop is formed between the sheets 4 (the state shown in FIG. 1 (B)), and the leading end of the sheet is completely separated from the separation claw 8 by the “stiffness” of the sheet 4, but the feed amount does not reach the transport roller 9 (The state of FIG. 1 (C)).

Next, in step S5, the feed motor 6a is stopped for a predetermined time (500 ms in this embodiment) in the above state, and the recording sheet 4 is stopped.
Is stopped temporarily. As a result, the recording sheet 4 in the unstable state immediately after the separation is stabilized. Next step
Proceeding to S6, the feed motor 6a is set to a predetermined amount (in this embodiment, 150s
tep) drive. This predetermined amount is a feed amount sufficient for the leading end of the recording sheet 4 to hit the nip portion between the transport roller 9 and the pinch roller 10a to form a loop (the state shown in FIG. 1D).

In the related art, since the steps S2 and S4 are continuous (in the above example, the feeding motor 6a is continuously driven for 500 steps), the recording sheet 4 in an unstable state immediately after separation is fed as it is. However, the recording sheet 4 is conveyed to the conveying roller 9 in a stable state by temporarily stopping the feeding as in this embodiment, and then the process proceeds to step S9.

If it is determined in step 2 that the recording sheet 4 is a postcard, the sheet is fed according to the thick sheet feeding mode.

That is, the process proceeds to step S7, and the sheet type variable H is set to “1”.
Is set, and in step S8, the feed motor 6a is driven by a predetermined amount (450 steps in this embodiment), and then the process proceeds to step S9.
The motor drive amount in step S8 is the same as that of the plain paper in that one recording sheet of the uppermost layer is separated by the separation claw 8, but the feed motor 6a continues to rotate and The transfer roller 9 and the pinch roller 10
The sheet 4 collides with the nip portion a, and the amount of the sheet 4 is sufficient to form a loop between the nip portion and the feeding roller 6.

In this embodiment, the amount of driving of the feed motor 6a for feeding plain paper to the nip portion is 500 steps in total, whereas the feed motor 6a is for feeding postcards to the nip portion. The driving amount is as small as 450 steps because, in the case of postcards, it is not necessary to form a large loop as with plain paper.

As described above, from the state where the leading end of the recording sheet 4 abuts the nip portion between the conveying roller 9 and the pinch roller 10a and forms a loop, the feeding motor 6a is turned on for a predetermined time (in this embodiment, in step S9). 500 ms), and the loop of the recording sheet 4 formed between the transport roller 9 and the feed roller 6 is stabilized.

Next, in steps S10 to S14, the transport motor 9a is set to 1
When the sheet detection sensor 15 detects the leading edge of the recording sheet 4 each time, and the sheet detecting sensor 15 does not detect the leading edge of the sheet while the sheet is conveyed by a predetermined amount (300 steps in this embodiment), When not turned on, the jam is displayed on the display unit on the operation panel 19 assuming that the jam has occurred.

On the other hand, if the sheet detection sensor 15 detects the leading edge of the sheet while the conveyance motor 9a is driven for 300 steps, the process proceeds to step S15 to determine whether the fed recording sheet 4 is plain paper or postcard based on the sheet type variable. In the case of paper, the process proceeds to step S16, and when the sensor 15 is turned on, the conveyance motor 9a is driven by a predetermined amount (900 steps in this embodiment) to be conveyed to the recording means 11 to finish sheet feeding and perform a recording operation. To start. If it is determined in step S15 that the fed sheet 4 is a postcard, the process proceeds to step S17, where the conveyance motor 9a is turned on when the sensor 15 is turned on.
Is driven by a specified amount (902 steps in this embodiment) to
To finish the sheet feeding and start the recording operation.

Here, if the drive amount of the transport motor 9a is
In contrast to 0 step, in the case of postcard, the difference from 902 step is due to the difference in “stiffness” of the sheet due to the difference in thickness, etc. This is because it was included.

By detecting the distinction between the plain paper and the postcard as described above and performing feeding suitable for each of them, when the plain paper is fed, it is not fed in an unstable state immediately after separation.
Further, when feeding postcards, there is no unnecessary feed stop time, and the throughput of the recording time is not reduced. Furthermore, even if there is a difference in the loop amount or the cueing amount due to the difference in the sheet type, it is possible to perform the appropriate feeding control for each sheet type by adding a correction value to each.

[Other embodiments]

The sheet feeding amount and the waiting time shown in the above-described embodiment are merely examples, and are appropriately set according to the size of the apparatus. For example, the longer the distance from the separation claw 8 to the nip portion between the conveyance roller 9 and the pinch roller 10a, the shorter the sheet standby time after separation can be. Is worse, the sheet standby time may be increased.

The rotation speed of the feed motor 6a and the like is maintained at a normal speed until the recording sheet 4 is separated, and after the separation, the rotation speed is reduced.
In between, the recording sheet 4 more stably forms a loop.

As a means for determining the sheet thickness, in the above-described embodiment, the sensor is used to determine whether the sheet is plain paper or a postcard based on the difference in sheet size. However, in a word processor or the like, the operator specifies the sheet size in advance and writes a sentence. Then, the host transmits the contents of the recording to the control unit of the recording apparatus and sends information on the recording sheet.
Therefore, it may be configured to determine whether the recording is the normal sheet recording or the postcard recording based on the sheet information, and select the sheet feeding mode according to the information.

Further, regardless of the sheet size, other detection may be performed using, for example, an optical sensor. Specifically, the sheet 4 to be fed is irradiated with light from an optical sensor. For example, when the sheet is a normal sheet having a thickness of about 100 μm, the light is transmitted through the sheet 4 to turn on the sensor, and the thickness is 200 μm.
When the sheet is a relatively thick sheet, the light may be blocked and the sensor may be turned off to determine whether the sheet is a normal sheet or a thick sheet.

As another configuration, a switch for inputting a normal sheet or a thick sheet may be provided on the operation panel 19, and a determination may be made based on information selected by the operator.

Further, in the above-described embodiment, an example in which the feeding roller 6 and the feeding roller 9 are used as the feeding means and the feeding means has been described. However, these are not necessarily limited to the roller-shaped one, and may be, for example, a rotating belt. May be something.

<Effect of the Invention> As described above, since the present invention is configured to feed a normal sheet and a thick sheet in different modes, it is possible to perform accurate feeding without a difference in feeding performance due to a difference in sheet type. Can be done.

Also, by providing an appropriate standby time when feeding the ordinary sheet, a stable loop can be formed and the generation of wrinkles can be effectively suppressed.

[Brief description of the drawings]

1 (A) to 1 (D) are explanatory views showing a sheet feeding state by a sheet feeding apparatus according to an embodiment of the present invention, FIG. 2 is a structural explanatory view of the sheet feeding apparatus, and FIG. FIG. 4 is a block diagram of a control system using the sheet feeding apparatus, FIG. 4 is a block diagram of a control system, FIG. 5 is a flowchart showing a sheet feeding procedure, and FIGS. 6 (A) to (C) are conventional sheets. It is explanatory drawing which shows a feeding procedure. 1 is a frame, 2 is a shaft, 3 is a mounting plate, 4 is a recording sheet, 5 is a pressing spring, 6 is a feeding roller, 6a is a feeding motor, 7 is a side guide, 8 is a separation claw, and 9 is a conveyance. Roller, 9a is a conveying motor, 10a and 10b are pinch rollers, 11 is a recording means, 11a is a guide shaft, 11b is a carriage, 11c is a recording head, 11d is an ink nozzle, 12a is a discharge roller, 12b is a spur roller, 13
Is a stacker, 14 is a sheet presence sensor, 15 is a sheet detection sensor, 16 is a sheet size detection sensor, 17 is a control unit, 17a is a CPU, 17bROM, 17c RAM, 18 is an interface, 19 is an operation panel, and 20 is an image signal An input device, 21 is a carriage motor, 22 is a motor driver, and 23 is a head driver.

Claims (1)

(57) [Claims] 1. A separating claw for pressing both front end portions of a sheet on an uppermost layer of a plurality of stacked sheets, a feeding unit for applying a feeding force to the sheet on the uppermost layer, Conveying means for conveying the sheets separated and fed one by one by the cooperation of the separating claw and the feeding means; and discriminating means for discriminating whether the stacked sheets are ordinary sheets or thick sheets. To feed a normal sheet selected by the result of the determination means, after removing a sheet on the uppermost layer from the separation claw, and then feeding the sheet to the conveyance means after a predetermined standby time. A normal sheet feeding mode for driving the sheet feeding means, and a feeding means for feeding a thick sheet after removing a sheet on the uppermost layer from the separation claw and feeding the sheet to the conveying means without passing the waiting time. Thick sea to drive feeding means And a sheet feeding device having: