JP3758141B2 - Paper transport device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sheet conveying apparatus that conveys a sheet (cut sheet) in a printing apparatus or the like.
[0002]
[Prior art]
In the paper transport device, control is performed according to the movement of the transport paper, such as forming an image on one side or both sides, or switching the paper transport path for discharging with the surface on which the image is formed facing up or down. ing.
[0003]
When transporting paper in a paper transport device that transports cut paper, the control unit manages the position of the transport paper from the detection timing and transport speed of the leading and trailing edges of the paper transported by the paper detection sensor. .
[0004]
In the above-described sheet conveying apparatus, when a plurality of sheets are successively conveyed sequentially, the conveying sheet may advance or be delayed for some reason. When the conveyance progress or delay more than the sheet interval occurs, the conveyance sheets interfere with each other to cause a paper jam, and therefore the conveyance progress or delay of the conveyance sheet is constantly monitored by the control device.
[0005]
As shown in FIG. 3 (a), it is ideal that two continuously conveyed sheets are always conveyed at a constant l interval, but as shown in FIG. 3 (b) or (c), they do not interfere with each other. If the conveyance advance is about ₁ or delay l ₂ , the paper conveyance is not affected. For this reason, an allowable value is set up to the conveyance advance or delay of the conveyance sheet shown in FIGS. 3B and 3C, and when the conveyance sheet conveyance advance or delay occurs by the sheet detection sensor and the control unit, A paper jam occurs when the tolerance value is deviated.
[0006]
Here, a case where the sheet transport path switching device is operated between the sheets 11 and 11 ′ will be described. When the operation of the sheet transport path switching device requires a maximum of lg as shown in FIG. 3D, the interval between the sheets 11 and 11 ′ must be wider than lg, and the sheet transport path switching device The operation must be started after the trailing edge of the sheet 11 passes the sheet transport path switching device. That is, the operation starts after the trailing edge of the paper 11 passes through the paper conveyance path switching device. If the operation does not end before the leading edge of the paper 11 ′ reaches the paper conveyance path switching device, the paper conveyance path switching is performed. The conveyance paper is caught in the apparatus, and a paper jam occurs. Therefore, in order to continue the sheet conveyance even when the conveyance sheet conveyance progress or delay occurs, the sheet advance and delay allowable values are set to l ′ ₁ and l ′ ₂ as shown in FIG. Control is performed so as not to cause a paper jam by the paper transport path switching device even when the paper advance / delay is maximized.
[0007]
[Problems to be solved by the invention]
However, the allowable value for the conveyance advance or delay of the conveyance sheet is changed from l ₁ , l ₂ to l ′ ₁ , l ′ ₂ as compared with the normal sheet conveyance control shown in FIGS. Thus, the paper jam detection margin for the paper conveyance advance or delay is reduced. This is because the paper that has been conveyed while allowing the advance or delay of l ₁ and l ₂ on the upstream side from the paper conveyance path switching mechanism is conveyed as l ′ ₁ and l ′ _{2 in} the paper conveyance path switching mechanism. There is also a problem that the possibility of paper jam is increased due to the allowable value of advance or delay, which leads to unnecessary paper jam.
[0008]
The present invention solves this problem. To provide a paper conveyance control method capable of minimizing a decrease in a paper jam detection margin in a paper conveyance path switching device in which a control trigger changes according to conveyance progress or delay of conveyance paper temporarily or with time. It is.
[0009]
[Means for Solving the Problems]
The paper transport device according to the present invention controls the transport roller, the paper detection sensor for detecting the transport paper, and the leading edge arrival timing of the paper detection sensor in the paper transport path of the printing apparatus that forms an image on the paper. Conveying continuously in a sheet conveying apparatus comprising: a sheet conveying path switching device; and a second sheet detecting sensor provided upstream of the sheet detection sensor with respect to the sheet conveying path switching device. The paper interval time is calculated from the trailing edge detection timing and the leading edge detection timing of the next paper to be detected, and the paper jam occurs when the paper interval time does not satisfy the time required for the switching operation of the paper transport path switching device. When the operation of the paper transport path switching device is not in time from the timing when the paper trailing edge is reached by the paper detection sensor Is accomplished by determining the operation timing of the sheet conveying path switching device by said second paper detection sensor.
[0010]
This will be described with reference to FIG. For comparison, FIGS. 5A to 5E are shown as the same time charts as FIGS. 3A to 3E.
[0011]
Figure 5 (f) and as shown in (g), the sheet 11 and the sheet 11 'is conveyed in the range of acceptable values l ₁ or l ₂ of the conveyor advances or delays, and the sheet 11 and the sheet 11' spacing paper If it is longer than the operation time lg of the conveyance path switching device, the conveyance is continued without the paper jam, thereby minimizing the decrease in the paper jam detection margin with respect to the normal paper jam detection control shown in FIGS. It is possible to provide a sheet conveying apparatus and a control method thereof.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0013]
FIG. 1 shows a schematic configuration of a paper transport path switching device of a paper transport device according to an embodiment of the present invention.
[0014]
The paper 11 transported from the upstream side is transported to the paper transport path 2 or the paper transport path 3 through the paper transport path 1. At the branch point of the paper transport paths 1 to 3, there is a gate 6 for distributing the paper 11 transported on the paper transport path 1 to the paper transport path 2 or the paper transport path 3. There are rollers 7-9 for conveying paper. Further, the sheet detection sensor 4 is located at a position separated from the gate 6 by the length L on the upstream side of the sheet conveyance path 1, and the sheet detection sensor 5 is located at a position further away from the sheet detection sensor 4. The sheet detection sensors 4 and 5 are switched from the off state to the on state when the leading end of the sheet 11 is detected, and are switched from the on state to the off state when the trailing end of the sheet 11 is detected. Here, the relationship between the roller 7 and the paper detection sensor 4 is not limited to that shown in FIG. 1, and the roller 7 may be between the paper detection sensor 4 and the gate 6.
[0015]
FIG. 2 shows the configuration of the control unit of the sheet conveying apparatus in this embodiment. The output signals of the paper detection sensors 4 and 5 are inputted to a control unit 10 composed of a CPU (Central Processing Unit), and the control unit 10 shows the output signal of the paper detection sensor 4 or 5 based on the output signal. 4, the rollers 7 to 9 and the driving units 12 to 15 of the gate 6 shown in FIG. 1 are controlled or a paper jam is detected.
[0016]
Next, the sheet conveying path switching operation of the sheet conveying apparatus having the above configuration will be described with reference to FIGS. When the leading edge of the paper 11 conveyed from the upstream side reaches the paper detection sensor 4, the output signal of the paper detection sensor 4 changes from the off state to the on state. When the paper 11 is transported as it is to the paper transport path 2 and the trailing edge reaches the paper detection sensor 4, the output signal of the paper detection sensor 4 changes from the on state to the off state. At this time, when the sheet 11 ′ transported to the sheet transport path 3 is transported following the sheet 11, the gate 6 passes through the gate 6 after the rear end of the sheet 11, and the leading end of the sheet 11 ′ begins at the gate 6. The operation of switching from the paper transport path 2 to the paper transport path 3 must be performed before reaching the position. Therefore, when the trailing edge of the paper 11 is detected by the paper detection sensor 4 (S1 in FIG. 4), the control unit 10 determines whether the paper detection sensor 4 has advanced or delayed the conveyance of the paper 11, and whether the allowable value is satisfied. A determination is made (S2). If the allowable value is exceeded, the roller that is conveying the paper 11 as a paper jam is stopped (S11). If the allowable value is satisfied, the gate 6 is switched to convey the paper 11 'following the paper 11. It is determined whether an operation is necessary (S3). If necessary, time measurement is started after the trailing edge of the paper 11 is detected by the paper detection sensor 4 (S4). When the time during which the trailing edge of the paper 11 is conveyed from the paper detection sensor 4 to the gate 6 has elapsed (S5), the operation of switching the paper conveyance path of the gate 6 is started (S6). During the time measurement up to the start of the operation of the gate 6 or after the start of the switching operation of the gate 6, when the leading end of the sheet 11 ′ is detected by the sheet detection sensor 4 (S 7), the controller 10 detects the sheet 11 ′ in the sheet detection sensor 4. The conveyance advance or delay is determined, and it is determined whether the allowable value is satisfied (S8). If the allowable value is exceeded, the roller that is transporting the paper 11 'as a paper jam is stopped (S11). If the allowable value is satisfied, the interval l' between the trailing edge of the paper 11 and the leading edge of the paper 11 'is satisfied. It is determined whether 'is sufficient as compared with the time lg required for the sheet conveyance path switching operation of the gate 6 (S9). If l ″ ≧ lg, the conveyance is continued. If l ″ <lg (S12), the leading edge of the sheet 11 ′ reaches the gate 6 before the switching operation of the gate 6 is completed. Since there is a possibility that the sheet 11 ′ may be pinched by the gate 6, the control unit 10 stops the roller that is conveying the sheet 11 ′ as a sheet jam (S11).
[0017]
Here, in performing this control, the sheet detection sensor 4 for detecting the leading edge or the trailing edge of the transport sheet does not have to be at the position shown in FIG. The paper detection sensor used for this control is best mounted at a point that should be the starting point of the operation of the gate 6 to be driven, but from the viewpoint of mounting or cost, the number of paper detection sensors is minimal. It is desirable to do. Accordingly, since the sheet detection sensor cannot always be mounted at the position shown in FIG. 1, the above-described control can be performed when the distance L between the gate 6 and the sheet detection sensor 4 is sufficiently secured. In this case, this control can also be performed using the paper detection sensor 4 and the paper detection sensor 5 mounted at an appropriate and distant point upstream from the position of the paper detection sensor 4. That is, when the trailing edge of the paper 11 passes the paper detection sensor 4 and the operation of the gate 6 is not in time, the timing of starting the operation of the gate 6 is set so that the trailing edge of the paper 11 is The same control can be performed by changing the combination, for example, measuring the distance between the paper 11 and the paper 11 ′ from the output signal of the paper detection sensor 4 starting from the time of passing.
[0018]
【The invention's effect】
As described above, according to the present invention, it is possible to minimize the decrease in the paper jam detection margin with respect to the paper transport path switching device that is controlled following the transport progress or delay of the transport paper in the paper transport device. A paper transport device and a control method that can be provided can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a sheet conveying apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram of a control device for a sheet conveying apparatus according to an embodiment of the present invention.
FIG. 3 is a time chart of a conventional paper conveyance device.
FIG. 4 is a flowchart of a sheet conveying apparatus according to an embodiment of the present invention.
FIG. 5 is a time chart showing the operation of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 2, 3 ... Paper conveyance path, 4, 5 ... Paper detection sensor, 6 ... Gate, 7, 8, 9 ... Paper conveyance roller, 10 ... Control part, 11 ... Conveyance paper, 12, 13, 14, 15 ... Driving unit for rollers 7 to 9 and gate 6.

Claims (1)

In the paper conveyance path of the printing apparatus that forms an image on the paper, a conveyance roller,
A paper detection sensor for detecting transport paper;
A sheet conveying path switching device for controlling the tip arrival timing of the paper detecting sensor,
A paper transport device comprising: a second paper detection sensor provided upstream of the paper detection sensor with respect to the paper transport path switching device ;
Calculating the time of paper interval from the trailing edge detection timing and the next sheet tip detection timing of the sheet to be conveyed continuously, not meet the time of the sheet interval time required to switch the operation of the sheet conveying path switching device and detects a paper jam when the, when from the trailing edge of the sheet reaches the timing by the paper detecting sensor is not in time the operation of the sheet conveying path switching device, the operation of the sheet conveying path switching device by said second paper detection sensor A paper conveying apparatus that determines timing .

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