JPH069110A - Paper feeding device - Google Patents

Abstract

PURPOSE:To reduce the frequency of carriage as far as possible by means of an auxiliary carrying roller, which may cause jam. CONSTITUTION:A CPU 45 raises an auxiliary carrying roller 5 only when a document detecting sensor 7 does not detect the front edge of the next document 2 in a prescribed period of time, after detecting the rear edge of the precedingly fed document 2 during continuous feeding of plural number of documents 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device provided in an image forming apparatus such as a facsimile, a copying machine or a printer.

[0002]

2. Description of the Related Art FIGS. 9 (a) and 9 (b) show a document feeding device generally provided in a facsimile.

The original document feeding apparatus is provided with an inclined feeding first
A pair of separation rollers (separation / feeding means) 3 for separating and feeding the originals (sheet materials) 2 stacked on top of each other, and an original that is raised to a predetermined position and stacked on the paper feed table 1. 2 is fed to the nip portion of the separation roller pair 3 and a vertically movable pre-conveying roller 5 and a document pressing member (sheet material) that presses the document 2 stacked on the sheet feeding table 1 against the pre-conveying roller 5 with a predetermined pressure. And a document detecting sensor (sheet material detecting unit) 7 for detecting the document 2 separated and fed by the separation roller pair 3.

Preliminary transport roller 5 in this document feeder
Has an auxiliary role for ensuring the separation and feeding by the separation roller pair 3. If the document 2 on the paper feed table 1 is fed to the nip portion of the separation roller pair 3 by the preliminary conveyance roller 5, the separation and feeding by the separation roller pair 3 can be surely performed.

The separation roller pair 3 rotates counterclockwise to feed only the lowermost paper sheet to the downstream, and the separating roller pair 3 rotates counterclockwise to return other than the lowermost paper sheet onto the paper feed tray 1. It comprises a retard roller 3B. The leading edge of the document 2 stacked on the paper feed table 1 comes into the nip portion of the separation roller pair 3.

The preliminary transport roller 5 is attached to the other end 10B of the arm 10 which vertically rotates about the one end 10A by an electromagnetic solenoid 9. Then, when the electromagnetic solenoid 9 is off, it descends to a predetermined position as shown in FIG. 9 (a) (non-conveying state), and when the electromagnetic solenoid 9 is on, it reaches a predetermined position as shown in FIG. 9 (b). Ascend (transport state).

The preliminary transport roller 5 is rotated counterclockwise by a preliminary transport motor (not shown) at the same time as the start of sheet feeding.

The document pressing member 6 is rotatable in the vertical direction about one end 6A, and is biased downward by a biasing spring (coil spring) 11.

The original detection sensor 7 is installed immediately downstream of a nip portion of a pair of conveying rollers (not shown) for conveying the original 2 separated and fed by the pair of separating rollers 3 onto an original table glass (not shown). There is.

The paper feeding operation of the original document feeder is controlled by a CPU (control means) for controlling the entire facsimile. Conventionally, the vertical movement operation of the pre-conveyance roller 5 is controlled as follows.

That is, the preliminary conveyance roller 5 is raised at the same time as the start of the sheet feeding operation, and when the document detection sensor 7 detects the leading edge of the document 2, the preliminary conveyance roller 5 is lowered.

When a plurality of originals 2 are continuously fed, when the original detecting sensor 7 detects the trailing edge of the previously fed original 2, the next original 2 is fed. The pre-conveyance roller 5 is raised to move the original detection sensor 7 to the original 2
When the leading edge of is detected, the pre-conveyance roller 5 is lowered, and the same control is repeated thereafter.

[0013]

However, in the above-mentioned document feeding apparatus of the prior art, when a plurality of documents 2 are continuously fed, the preliminary feeding roller 5 is fed every time one document 2 is fed. Since the ascending operation and the descending operation are repeated, when the original 2 is a thin thin paper or the like, a jam may occur between the separation roller pair 3 and the original pressing portion 6 as shown in FIG.

That is, as shown in FIG. 9 (a), when the pre-conveying roller 5 is lowered, the pressing force of the document pressing unit 6 is applied to the plurality of documents 2 stacked on the paper feed table 1. Is only slightly working, so the frictional force between the originals is small. Therefore, even if the lowermost sheet is sent by the feed roller 3A of the separation roller pair 3, the other document 2 receives only a slight force in the carrying direction.

However, as shown in FIG. 9 (b), when the pre-conveyance roller 5 is raised, the original document pressing member 6 working on the plurality of original documents 2 stacked on the paper feed tray 1 is moved. Since the pressing force is increased, the frictional force between the originals is significantly increased. For this reason, when the lowermost sheet is fed by the preliminary feeding roller 5, the other originals 2 also receive the force in the feeding direction.

Accordingly, while the pre-conveying roller 5 applies the conveying force to the lowermost sheet, the other originals 2 are also continuously fed while being blocked by the separating roller pair 3, so that the originals 2 are elastic. In the case of weak thin paper, as shown in FIG. 10, a jam may occur between the separation roller pair 3 and the document pressing member 6.

Therefore, the present invention has been made in view of the above-mentioned circumstances, and it is possible to control the sheet feeding operation that can reduce the number of times of conveyance by the preliminary conveying roller that causes a jam as much as possible, and the sheet feeding. An object of the present invention is to provide a sheet feeding device capable of performing operation control in response to changes in conditions such as environment and sheet material.

[0018]

According to the present invention, a paper feed tray (1) is provided.
Separation and feeding means (3) for separating and feeding the sheet materials (2) stacked on the sheet one by one, and a sheet material that is raised to a predetermined position and is stacked on the sheet feeding table (1). The pre-conveying roller (5) that can move up and down to feed (2) to the separating and feeding means (3), and the sheet material (2) stacked on the paper feed table (1) are paired with the pre-conveying roller pair ( Sheet material pressing means (6) for pressing the sheet material against the sheet material (5) with a predetermined pressure; sheet material detecting means (7) for detecting the sheet material (2) separated and fed by the separating and feeding means (3); And a control means (45) for controlling the paper operation.

In the present invention, in order to achieve the above object, the control means (45) is configured so that when the sheet material (2) is continuously fed, the sheet material detection means (7) is Only after the trailing edge of the sheet material (2) that has been separated and fed first is detected and then the leading edge of the next sheet material (2) is not detected even after a specific time has elapsed, the pre-conveying roller (5). Is characterized in that

Further, the control means (45) determines that the sheet material detection means (7) does not detect the leading edge of the sheet material (2) even after a lapse of a specific time (TS) after the start of the sheet feeding operation. Only, the above-mentioned equipment conveying roller (5) is raised.

Further, the control means (45) has a paper feed time (TMAX) required from the start of the paper feed operation of the first sheet material (2) to the detection of the leading edge of the sheet by the sheet material detection means (7). Based on the above, the specific time (TS) at the time of feeding the second and subsequent sheet materials is set.

[0022]

According to the above-mentioned structure, the specified time (TS) has elapsed after the start of the paper feeding operation both when the first sheet material (2) is fed and when the second and subsequent sheet materials (2) are fed. Only when the separation and feeding by the separation and feeding means (3) is not performed during the period, the pre-conveyance roller (5) performs the conveyance.

Therefore, each time the sheet material (2) is fed, it is not conveyed by the preliminary conveying roller (5), and the preliminary conveying roller (5) minimizes the number of conveyance times.

As a result, even if the sheet material (2) is thin paper having a weak stiffness, jamming is less likely to occur. Further, since the raising operation and the lowering operation of the preliminary conveyance roller (5) are not frequently performed, the life of the preliminary conveyance roller (5) is extended.

Further, the rising timing of the pre-conveying roller (5) at the time of feeding the second and subsequent sheet materials is determined based on the feeding time (TMAX) of the first sheet material (2). It can respond appropriately to changes in conditions such as the environment and seat material.

As a result, the rising timing of the pre-conveyance roller (5) is not shifted, the feeding time becomes longer, and the pre-conveyance roller (5) is unnecessarily raised.

The reference numerals in parentheses are for reference to the drawings and do not limit the structure of the present invention in any way.

[0028]

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

Here, the case where the present invention is applied to a document feeding device of a facsimile is shown. <Embodiment 1> FIG. 1 shows a facsimile equipped with a document feeder according to Embodiment 1 of the present invention.

First, the outline of this facsimile will be described.

This facsimile includes a facsimile main body 20.
A document feeding device 21A is provided therein, and the document feeding device 21A feeds a document 2 to be transmitted to a counterpart facsimile to a document reading device 22 in the facsimile main body 20.

Document 2 fed from the document feeder 21A
Is conveyed to the document reading device 22 by the document conveying device 23.

The document feeder 23 is a document feeder 21A.
The original 2 sent by means of a conveyance roller 25 that conveys the original 2 onto an original platen glass 27, which will be described later, and a pair of discharge rollers 26 that ejects the original document 2 that has been read on the original platen glass 27 to the outside of the machine. .

The document reading device 22 reads the document 2 twisted and conveyed by the document conveying device 23, and transmits an image signal to a facsimile of the other party.

The original document reading device 22 serves to reflect an original plate glass 27 as an original document reading section, a light source 29 for irradiating the conveyed original document 2 with light, and a light L reflected from the conveyed original document 2. Reflecting mirrors 30, 31 and lens 32
And a photoelectric conversion element (CCD) 33 and the like.

Further, the facsimile main body 20 is provided with an image information recording section (printer section) 35 for recording the image information received from the partner facsimile.

The image information recording section 35 includes a roll-shaped recording sheet 37 rotatably stored in a storage section 36, a platen roller 39 for pulling out the recording sheet 37 from the storage section 36, and a platen roller 39 on the platen roller 39. Recording head 40 for recording (printing) the received image on the recording sheet 37
And a cutter 41 for cutting the recording sheet 37 after image recording to a predetermined length, and a pair of discharge rollers 43 for discharging the cut recording sheet 37 to a stacker 42 outside the machine.

Next, the document feeder 21A of this embodiment will be described.

The document feeding device 21A of this embodiment has the same elements as those of the document feeding device of the above-mentioned conventional example, namely, the separation roller 3, the pre-conveying roller 5, the document pressing member 6, and the document detection sensor 7. And are provided.

The pre-conveying roller 5 is controlled by the control circuit shown in FIG. 2 so as to control its rotation ON / OFF and its vertical movement operation.

CPU for controlling the operation of the entire facsimile
A document detection signal from the document detection sensor 7 is input to 45. Further, the CPU 45 outputs a drive signal to the solenoid driver 46 and the motor driver 47.

When a drive signal is output from the CPU 45 to the solenoid driver 46, the solenoid driver 46
Energizes the electromagnetic solenoid 9 and the electromagnetic solenoid 9
Turns on. As a result, the pre-transport roller 5 moves up to the document transport position.

When the CPU 45 outputs a drive signal to the motor driver 47, the motor driver 47 energizes the drive motor 49 and the drive motor 49 is turned on. As a result, the pre-transport roller 5 rotates.

Next, with reference to FIG. 3, a control example of the vertical movement operation of the pre-conveyance roller 5 performed in the CPU 45 will be described.

When the paper feeding operation is started, time measurement is started (S1). Then, the original detection is checked (S
2) If the document 2 is not detected by the document detection sensor 7 even if the measurement time (TIME) reaches the specific time (TS) (S3), the preliminary conveyance roller 5 is raised (S4). As a result, the pre-conveyance roller 5 separates the original 2 from the separation roller pair 3
Send to. Further, when the original 2 is detected within the specific time (TS), the preliminary conveyance roller 5 is not raised but kept lowered.

After that, the time measurement is started again (S
5). Then, the original detection is checked (S6), and when the original 2 is detected by the original detection sensor 7, the preliminary conveyance roller 5 is lowered (S9). If the document 2 is not detected even after the error time (TOUT) (S7), the preliminary conveyance roller 5 is lowered (S8), and the process ends in error.

When the leading edge of the original 2 is detected in S2 or S6, the reading operation of the original 2 by the original reading device 22 is performed (S10). Meanwhile, the detection of the trailing edge of the document 2 conveyed by the document conveying device 23 is checked (S1).
1).

Then, if the rear end of the original is detected by the original detection sensor 7, it is checked whether or not there is the next original 2 (S12). If the next original 2 exists, the process returns to S1 again and the next original is detected. The measurement of the time for feeding the original 2 is started. If there is no next original 2, this sequence ends.

FIGS. 4A and 4B are timing charts of the document detection sensor 7 and the pre-transport roller 5 in the above control example.

FIG. 4A shows the case where the document detection sensor 7 does not detect the leading edge of the document 2 even if the measurement time (TIME) exceeds the specific time (TS) (TIME> TS). In this case, the pre-conveyance roller 5 rises and sends the document 2 to the nip portion of the separation roller pair 3.

FIG. 4B shows a case where the document detection sensor 7 detects the leading edge of the document 2 when the measurement time (TIME) is within the specific time (TS) (TIME <TS). In this case, the pre-transport roller 5 does not move up but remains down.
Therefore, the jam caused by the pre-transport roller 5 does not occur.

Here, in consideration of the reduction of the sheet feeding time in the case of FIG. 4A, the certainty of the document detection in the case of FIG. 4B, etc., the specific period (TS) is set to 0.8 seconds, for example. Is set to. <Embodiment 2> In the document feeder 21B of Embodiment 2 of the present invention shown in FIG. 5, only the separating and feeding means is used in Embodiment 1 described above.
The original feeding device 21A is changed in configuration. here,
Instead of the separating roller pair 3, a separating and feeding means including a feed roller 50 and a friction piece 51 is used.

CPU 4 in the case of the present document feeder 21B
FIG. 6 shows an example of control of the vertical movement operation of the preliminary conveyance roller 5 in No. 5.

In the case of the original document feeder 21B, when the sheet feeding operation is started, first, the preliminary conveying roller 5 is raised (S
4) The pre-conveying roller 5 feeds the document 2 into the nip portion between the feed roller 50 and the friction piece 51. This point shows an example of control of the document feeder 21A of the first embodiment (FIG. 3).
Different from <Third Embodiment> FIG. 7 shows a document feeder 21 of the first embodiment.
Another control example of the vertical movement operation of the preliminary conveyance roller 5 in the CPU 45 in the case of A is shown.

In this control example, the specific time (TS) is automatically changed according to the change of conditions such as the environment and the material of the original, so that the pre-conveying roller 5 is raised at an appropriate timing.

When the paper feeding operation is started, F, TS, TMA
Initialize X as 0 (S1). Here, F is a flag indicating the upper and lower positions of the pre-conveyance roller 5, and 0 is lower,
1 indicates the top. Further, TS is a specific time, and TMAX is a paper feeding time of the first original. Then, the measurement (TIME) is set to 0 (S2).

Then, the document detection is checked (S3),
Even when the measurement time (TIME) reaches the specific period (TS) (S4), the original detection sensor 7 does not detect the original 2 and the preliminary conveyance roller 5 is lowered (S5).
The preliminary conveyance roller 5 is raised to set F to 1 (S6). Since the specific time (TS) is 0 for the first document,
The pre-conveyance roller 5 always rises after the start of feeding. As a result, the pre-conveyance roller 5 sends the original 2 to the separation roller pair 3.

After that, if the document 2 is not detected even after the error time (TOUT) has passed (S7), the process ends with an error.

When the document 2 is detected within the specific time (TS), the preliminary conveyance roller 5 is not raised but is kept lowered.

When the document 2 is detected by the document detection sensor 7, it is checked whether it is the first document (S).
8). And for the first original (TMAX = 0)
Sets the feeding time (TMAX) of the first document and the specific time (TS) (S9). First, the measurement time (TIM
Substituting E) into the paper feeding time (TMAX) of the first original. The measurement time (TIME) at this time is the time from the start of the paper feeding operation until the first document is detected by the document detection sensor 7. That is, it indicates the time from the start of the paper feeding operation to the feeding of the first original. Next, a value obtained by subtracting the paper feed time (TMAX) of the first original from the error time (TOUT) is substituted for the specific time (TS). As a result, the longest time during which the preliminary transport roller 5 is lowered is set to the specific time (TS) without causing an error.

The first original is the TMAX, TS
Is not set.

Next, it is checked whether or not the preliminary conveyance roller 5 is raised (S10), and when it is raised (F =
1) lowers the pre-conveyance roller 5 and sets F to 0 (S1)
1). Here, the reading operation is performed (S12).

During the reading operation, the trailing edge of the document 2 conveyed by the document conveying device 23 is detected (S13). Then, if the trailing edge of the original is detected, it is checked whether or not there is the next original 2 (S14).
The process returns to S2 again to start measuring the time for feeding the next original 2. If there is no next original 2, this sequence ends.

FIGS. 8A and 8B are timing charts of the document detection sensor 7 and the pre-transport roller 5 in the above control example.

FIG. 8A shows the case where the document detection sensor 7 does not detect the leading edge of the document 2 even when the measurement time (TIME) exceeds the specific time (TS) (TS <TIME <TOUT). In this case, the pre-conveyance roller 5 rises and sends the document 2 to the nip portion of the separation roller pair 3.

Here, the feeding time of the first original (TM
Since the specific time (TS) is set based on AX), an error may occur because the time until the second document is fed is too long after the first document is fed. Never. That is, TIME> TOUT does not hold.

FIG. 8B shows the case where the document detection sensor 7 detects the leading edge of the document 2 when the measurement time (TIME) is within the specific time (TS) (TIME <TS). In this case, the pre-transport roller 5 does not move up but remains down. Therefore, the jam caused by the pre-transport roller does not occur.

Although not shown here, the specific time (TS) at the start of the paper feeding operation is set to a predetermined value, and the pre-conveying roller 5 is raised even when the first original is fed. Can be made to wait for a specific time (TS).

Further, although the case where the present invention is applied to the original feeding devices 21A and 21B of the facsimile has been described here, the present invention can be widely applied to the feeding devices of other image forming apparatuses. .

[0070]

As described above, in the paper feeding apparatus of the present invention, the sheet material detecting means is fed first after the paper feeding operation is started or when a plurality of sheet materials are continuously fed. After the trailing edge of the sheet material is detected, the preliminary feeding roller is controlled to rise only when the sheet material detection unit does not detect the leading edge of the sheet material even after a specific time has elapsed. It is possible to reduce the number of times of transportation by.

For this reason, the jam caused by the pre-conveyance roller is less likely to occur.

Further, since the specific time is set on the basis of the paper feeding time of the first sheet material, the pre-conveying roller is raised at an appropriate timing corresponding to the change of conditions such as environment and sheet material. be able to.

Therefore, it is possible to prevent the feeding timing of the pre-conveyance roller from being shifted and the pre-conveyance roller to be unnecessarily raised.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view showing a configuration of a facsimile equipped with a document feeding device according to a first embodiment of the invention.

FIG. 2 is a block diagram of a control circuit that controls the operation of a preliminary conveyance roller of the document feeding apparatus.

FIG. 3 is a flowchart showing an example of control of a vertical movement operation of a preliminary conveyance roller of the document feeder.

FIG. 4 is a timing chart of a document detection sensor and a preliminary conveyance roller in the control example.

FIG. 5 is a vertical cross-sectional side view showing the configuration of a facsimile equipped with a document feeding device according to a second embodiment of the invention.

FIG. 6 is a flowchart showing an example of control of a vertical movement operation of a preliminary conveyance roller of the document feeder.

FIG. 7 is a flowchart showing another control example of the vertical movement operation of the preliminary conveyance roller of the document feeding apparatus according to the first embodiment of the present invention.

FIG. 8 is a timing chart of a document detection sensor and a preliminary conveyance roller in the same control example.

FIG. 9 is a vertical cross-sectional side view showing the configuration of a conventional sheet feeding device provided in a facsimile.

FIG. 10 is a vertical cross-sectional side view showing a jam generated when a document is conveyed by a preliminary conveyance roller in the document feeding device.

[Explanation of symbols]

 1 Paper Feeding Table 2 Original (Sheet Material) 3 Separation Roller Pair (Separation Feeding Means) 5 Preliminary Conveying Roller 6 Original Pressing Member (Sheet Material Pressing Means) 7 Original Detection Sensor (Sheet Material Detection Means) 45 CPU (Control Means) 50 Feed Roller (Separate Feeding Means) 51 Friction Piece (Separate Feeding Means) TS Specific Time TMAX Feeding Time of First Original Document

Claims (3)

[Claims] 1. Separation and feeding means for separating and feeding sheet materials stacked on a paper feed table one by one, and sheet materials which are raised to a predetermined position and stacked on the paper feed table. A vertically movable pre-conveying roller that feeds to the separating and feeding unit, a sheet material pressing unit that presses a sheet material stacked on the sheet feeding table against the preliminary conveying roller with a predetermined pressure, and the separating and feeding unit. In a sheet feeding device provided with a sheet material detecting means for detecting the sheet material separated and fed by the sheet feeding means, and a control means for controlling a sheet feeding operation, the control means is a continuous sheet feeding of a plurality of sheet materials. When the sheet material detecting means detects the trailing edge of the sheet material previously separated and fed, the preliminary conveyance is performed only when the leading edge of the next sheet material is not detected even after a specific time has elapsed. Characterized by raising the roller Sheet feeder that. 2. The control means raises the storage / conveyance roller only when the sheet material detection means does not detect the leading edge of the sheet material even after a lapse of a specific time after the start of the sheet feeding operation. The sheet feeding device according to claim 1, wherein 3. The sheet feeding device for the second and subsequent sheets based on the sheet feeding time required from the start of the sheet feeding operation of the first sheet material to the detection of the leading edge of the sheet by the sheet material detecting unit. 2. The paper feeding device according to claim 1, wherein the specific time for paper is set.