JPH02204223A - Sheet supply/sending device - Google Patents

Abstract

PURPOSE:To make it possible to immediately transfer a paper sheet to a position capable of feeding by providing a means for shortening a time required from the beginning of actuation of a driving means to the beginning of movement of the sheet. CONSTITUTION:When a small capacity cassette 2 is inserted into a feeding device, a spacer member 14 is mounted on a cassette rail 13 in the horizontal and arrow mark direction as shown in the figure, before inserting the cassette 2. This spacer member 14 has a slope 15 on the front face, and at mounting the spacer member 14 is shown in the figure, a lifter plate 5 is elevated up to the position in close proximity to the intermediate plate 3 of the cassette 2. Consequently, when a surface level of paper becomes under a prescribed level, the lifter plate 5 immediately abuts to the intermediate plate 3, even though it is elevated little by little, and control of paper surface can be performed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a sheet feeding device for an image forming apparatus such as a copier or a printer, particularly a sheet feeding device that can use both a large-capacity cassette and a small-capacity cassette as a sheet loading cassette. It is related to.

[Conventional technology] Conventionally, three types of rollers, a pick-up roller, a foot roller, and a reversing roller, are used to move stacked sheets into one
The so-called retard roller method, which separates and feeds sheets one by one and transports them to the image forming section, requires a lifter mechanism to maintain the height of the top surface of the stacked sheets at an approximately constant level. The contact pressure between the feed rollers and the sheet can be easily kept constant regardless of the sheet loading amount by using the roller's own weight, etc., so it can be used not only for retard roller type sheet feeding methods but also for all sheet feeding methods. It is also an effective method.

In FIGS. 17 to 19, l is the main body of an image forming apparatus such as a copying machine or a printer, 2 is a cassette, 3 is an intermediate plate that can be rotated around a shaft 2a fixed to the cassette 2, and S is a transfer plate. It is a sheet of paper etc. 4 is a height detection sensor that measures the height of the top surface of the seat; 5 is a lifter plate that raises the middle plate; and a lifter shaft 6 that is rotated by a lifter drive motor 6a.
is fixed to. 7 is a feeding roller, 8 is a conveying roller,
Reference numeral 9 indicates a retard roller, and reference numeral 10 and 11 indicate a pair of conveying rollers. 50 is a control circuit that controls the lifter drive motor 6a, etc.;
Reference numeral 51 denotes a cassette attachment sensor that detects that a cassette is attached to the main body 1.

In a general glue lid mechanism, the control method for the height of the top surface of the MIE sheet is different before the start of the feeding operation and during the continuous feeding operation.

This will be explained below using the flowchart shown in FIG. That is, when the cassette 2 with sheets stacked on the middle plate is attached to the image type JJt apparatus main body, the cassette attachment sensor 51 is turned on (step sl), and the height detection sensor 4 provided near the feeding roller detects the stacked sheets. until it is detected that the height of the top surface has reached a level that allows feeding (step s2)
In step S3) of repeating the rotation of the lifter drive motor 6a by a predetermined time T, the lifter plate 5 continuously lifts the cassette middle plate 3, and thereafter becomes ready for feeding. This is called "continuous rise mode" here.

Next, in step S4, wait until there is a sheet feed signal,
When there is a sheet feeding signal, the sheet is fed (step S5).As the sheet is fed, the height of the top surface of the sheet gradually decreases, and when the top surface of the sheet falls below a certain predetermined height, it is determined that the height is high. When the height is detected by the sensor 4 (step s6), the lifter drive motor 6a is rotated for a predetermined minute time t (Tit) to raise the middle plate and raise the top surface level to a specified height or higher. At this time, since the main body of the apparatus is continuously feeding, the height of the top surface constantly fluctuates due to fluttering and vibration of the sheet during feeding.

Therefore, in order to prevent the top surface height detection sensor from chattering, for example, each time a sheet is fed, the height detection sensor measures the top surface height for a certain period of time, and the average height during that time is set to a specified value. If it falls below, the lifter will lift the middle plate. This method of controlling the glue lid during continuous feeding is called the "intermittent minute rise mode."

The "continuous lift mode" before the start of the feeding operation is necessary to quickly raise the top surface of the sheet to the specified height when the cassette is loaded with a small amount of paper. In this case, the height of the top surface of the sheet may already be above the specified level when the cassette is installed, and in this case, there is no continuous rise mode, and the process moves from step s2 to step s4 and the feeding operation starts immediately. Then, the lifter control is performed in the intermittent minute amount raising mode.

[The WR problem to be solved by the invention However, when a large-capacity cassette and a small-capacity cassette are used together with such a lid, the following drawbacks occur.

In Figure 12, 1 is the main body of the printer, the chain double-dashed line is a large-capacity cassette, 2 is a small-capacity cassette, 3 is a cassette middle plate that can be rotated around the shaft 2a, and S is a sheet such as transfer paper. . The height detection sensor 4 measures the height of the top surface of the sheet, and if the height is below a specified level, the shaft 6 is moved to the lifter drive motor 6a.
The lifter plate 5 is rotated for a certain minute time to raise the lifter plate 5 minute by minute. 7 and 8 are feeding rollers, 9 is a retard roller, 1
0.11 is a pair of conveying rollers. Now figure 12 is paper,
Because a small-capacity cassette full of paper was installed, continuous paper feeding started without the lifter's continuous lift mode.
11ff, the height detection sensor 4 detects that the height of the top surface of the sheet is below the specified level, and the lifter plate 5 is raised by a minute amount in an intermittent minute amount raising mode. By the way, when the large-capacity cassette shown by the two-dot chain line in FIG. 17 is installed, the lifter plate 5 immediately comes into contact with the cassette middle plate 36 and raises it, making it possible to maintain the height of the top surface of the sheet at a specified level. However, since the lifter lid plate 5 is far from the middle plate 3 when the small capacity cassette 2 is installed, the uppermost surface of the sheet is removed by continuous feeding before the lifter plate 5, which is lifted up in the intermittent minute amount mode, reaches the middle plate 3. As shown in FIG. 18, the leading edge of the fed sheet gets caught on the front wall of the cassette 2, causing a jam.

The above problem also occurs in sheet feeding devices that do not use both large-capacity and small-capacity cassettes.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems.An object of the present invention is to provide a method for moving a sheet to a position where it can be immediately fed by actuation of a driving means. The purpose of the present invention is to provide a sheet feeding device.

The configuration of the present invention for achieving the above object includes a placing means for storing sheets, a moving means for moving the sheet placed on the placing means to a position where it can be fed, and a driving means for driving the moving means. The sheet feeding apparatus has a driving means for driving the sheet, and a means for shortening the time required from the start of operation of the driving means to the start of movement of the sheet.

[Embodiment] FIGS. 1 to 3 show a first embodiment of the present invention. FIG. 1 shows a case where a large-capacity cassette is installed in a sheet feeding device. Here, 1 is the main body of the image forming apparatus, 12 is a large-capacity cassette, 3 is a cassette middle plate, and S is a stacked sheet.
The pick-up roller 7 sends S between the roller pair 8 and 9. The roller 9 is connected to a drive source via a power transmission mechanism (torque limiter) that rotates when a torque of a predetermined value or more is applied as a load. When one sheet is fed, the load torque applied from the sheet to the torque limiter via roller 9 exceeds a predetermined value, the torque limiter rotates, and the roller 9 stops the sheet being conveyed by roller IO. Rotates driven by. However, when two or more sheets are fed, the frictional force between the sheets is applied to the torque limiter as a load torque via the roller 9, and since this value is less than a predetermined value, the torque limiter is turned off. Instead, the roller 9 rotates in a direction to return the sheet to the cassette 12.

At this time, if the sheets are not double-fed, they are fed directly to the image forming section via the pair of transport rollers 10 and 11, but if they are double-fed, the lower sheet is separated by rotating the roller 9 in the reverse direction. This is a so-called retard roller system in which one sheet of paper is fed to the image forming section via a pair of rollers 10 and 11.

The control block diagram of the feeding device lid drive motor 6a is the same as that shown in FIG. 19, and the flowchart shown in FIG. 20 is performed to perform the control as described above.

FIG. 2 shows a small capacity cassette inserted into these feeders t and H. In this case, in order to mount a small capacity cassette, the spacer member 14 is mounted on the cassette rail 13 in the direction of the horizontal arrow in the figure prior to insertion of the cassette. This spacer member 14 has a shape as shown in FIG. 3, and has a slope 15 on the front surface. When the spacer member is attached as shown in FIG. 2, the lifter plate 5 is raised by the slope 15 to a position extremely close to the middle plate 3 of the small capacity cassette.

Therefore, as soon as the paper surface level falls below the specified level, even if the lid plate intermittently rises by a minute amount, it immediately comes into contact with the middle plate 3, and the paper surface can be controlled.

[Other Embodiments] FIGS. 4 and 5 show a second embodiment, in which a lever 18 is held by the spacer member 16 so as to be swingable about a shaft 17.

Therefore, when a small-capacity cassette is installed and the paper level falls below the specified level while feeding one paper, the lifter plate 5 can immediately lift the middle plate 3 via the lever 18 as shown in FIG. 5, and the paper level is controlled. is possible, and jams do not occur.

A third embodiment is shown in FIGS. 6-9. FIG. 6 shows a large-capacity cassette, FIG. 7 shows a small-capacity cassette, and S indicates stacked sheets. Here, 19 is a frame for inputting the paper size to the main body of the image forming apparatus. The small-capacity cassette shown in FIG. 7 is provided with a small-capacity frame 21, and the large-capacity cassette shown in FIG. The same objective as in the previous example can be achieved by performing a lifter raising operation for a certain period of time until the lifter plate reaches the vicinity of the intermediate plate, prior to the feeding operation, only when .

This control will be explained using the block diagram of FIG. 9 and the flow chart of FIG. 1O. The explanation of the parts common to FIGS. 19 and 20 will be omitted. In FIG. 10, when the cassette device sensor 51 detects the attachment of a cassette (step s1), the sensor 52 detects whether the attached cassette is a small capacity cassette in step sll. For small capacity cassettes, step s1
2, the lifter drive motor 6a is operated for a predetermined time T. rotate it,
After moving the lifter plate 5 to a position close to the intermediate plate 3 as shown by the one-dot chain line in FIG. 8, the process moves to step S2.

In the case of a large capacity cassette, the process moves from step sll to step S2. After step s2, the control described in FIG. 20 is performed.

In this embodiment, since a spacer member is not required, a cassette site rail 20 is provided for the large-capacity cassette, and the large-capacity cassette is inserted as shown in FIG. In the case of a small capacity cassette, the cassette rail 22 is
Place the cassette on top of the cassette.

A fourth embodiment is shown in FIGS. 13 and 14.

In this embodiment, a contact sensor 23 is attached to the tip of the lid plate 5, and when the cassette is installed, the lifter rises unconditionally, and when the sensor 23 operates, that is, the lifter plate contacts the middle plate of the cassette. By the way, the lifter drive motor M25 is stopped according to an instruction from the CPU 24.

Explaining with reference to the block diagram of FIG. 15 and the flowchart of FIG. 16, when the cassette device is confirmed in step sl, the contact sensor 23 is
Determine whether it is N or not. If the contact sensor 23 is not ON, the lifter drive motor 25 is rotated for a predetermined time T in step s22, and the process returns to step s21. This is repeated until the contact sensor 23 is turned on. If the contact sensor 23 is turned on in step s21 (FIG. 14), the process moves to step 52. After step s2, the second
The same control as in the flowchart of FIG. 0 may be performed, and this operation may be configured to be performed only when a small capacity cassette is attached.

In the embodiments described above, the feeding device uses a beam tart roller, but the present invention can be applied to any other feeding device such as a feeding device using a separation bat.

Also t53. In the fourth embodiment, the lifter plate may be raised to the vicinity of the intermediate plate before or immediately after the start of the feeding operation.

[Effects of the Invention] As described above, according to the present invention, since the time required from the start of operation of the driving means to the start of movement of the sheet is short, it is possible to prevent jams and feeding errors.

[Brief explanation of the drawing]

#! Figures 1 to 3 are the first embodiment, Figures 4 to 5 are the second embodiment, Figures 6 to 12 are the third embodiment, and Figures I3 to 16 are the third embodiment. Embodiment 4 FIGS. 17 to 20 are diagrams showing conventional examples. 1 is an image forming apparatus main body, 2 is a small capacity cassette, 3 is a cassette middle plate, 4 is a height detection sensor, 5 is a lifter plate, 7 is a feeding roller, 8 is a conveyance roller, 9 is a retard roller, 10
．． 11 is a pair of conveying rollers, 12 is a large capacity cassette, 14.
16 is a spacer member, 18 is a lever, 20 is a sight rail, 21 is a small capacity piece, 23 is a contact sensor, 24, 5
0 is a CPU, and 6a and 25 are lifter drive motors.

Claims (1)

[Claims] (1) A loading means for loading the sheet; Feed the sheet placed on the aforementioned placement means. a moving means for moving it to a position where it can be sent; Driving means for driving the moving means; From the start of the operation of the drive means, the Shorten the time it takes for the route to start moving. A means for shrinking the A sheet feeding device having a