JPH0344656A - Automatic document feeder - Google Patents

Abstract

PURPOSE:To surely set a document at a specified position by counting number of pulses in a certain time when a conveyance belt is driven in a reverse rotating direction, comparing the counted value with a reference value and correcting the driving quantity of the belt based on the comparison output. CONSTITUTION:A CPU 23 counts the number of pulses X outputted from a pulse output switch 17 for a time Tmsec which is the sum of the normal rotating period of a belt motor 25 for conveyance, a brake signal output time and a reverse driving signal output time. The CPU 23 obtains a difference between the number of pulses X and the reference value N previously set at the time of an experiment and adds it to a CPSET as a correction pulse X' to calculate the CPSET. Thus, the variation of the moving quantity of the belt caused by the difference of the size of the document or the kind of paper, in other words, an error caused by the variance of a stopping position is corrected and the document is surely set at the specified position.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an automatic document feeding device that is installed in a copying machine or the like and automatically sets a document in a predetermined position. The present invention relates to an automatic document feeder that conveys documents using a conveyor belt.

<Prior Art> An automatic document feeder including a mechanism for conveying a document by a conveyance belt is known.

In this type of automatic document feeder, in order to accurately align the trailing edge of the document with the reference line provided at the set position, the document is slightly overrun from the set position, and then the conveyor belt is driven in the opposite direction. switch back the manuscript,
Some documents employ a method in which the edge of the document collides with a protrusion provided at a reference line position.

<Problems to be Solved by the Invention> However, when a document is conveyed by a conveyor belt, the difference between the conveyor belt and the conveyor path surface (
For example, the contact ratio with contact glass (for example, contact glass) changes. Usually, the surface of the conveyor belt is roughened to increase the coefficient of friction. Therefore, when transporting a small-sized original, the contact area between the transport belt and the transport path surface is large, and a large force is required to drive the transport belt. On the other hand, the larger the size of the document is transported, the smaller the contact area between the transport belt and the transport path surface, and the smaller the driving force is required. As described above, the difference in document size causes load fluctuations in a driving means, such as a motor, for driving the conveyor belt.

Similarly, differences in document types, such as paper quality and thickness, also cause motor load fluctuations.

Therefore, if the size and type of the original changes, the amount of overrun will vary when the set position is overrun, and when the original is switched back, the trailing edge of the original will not collide with the protrusion properly and will not stop accurately on the reference line. Something happened.

The present invention has been made to eliminate these drawbacks, and an object of the present invention is to provide an automatic document feeder that can accurately set documents at predetermined positions.

Means for Solving the Problems> The present invention relates to an automatic document feeder in which a document to be set at a predetermined position is conveyed by a conveyor belt. belt driving means for driving the conveying belt in a first direction by a predetermined amount and then driving the conveying belt in a second direction opposite to the first direction for a certain period of time; and driving the conveying belt in the second direction. a pulse counting means for counting the number of pulses output from the pulse output means within a certain period of time; a comparing means for comparing the counted value of the pulse counting means with a predetermined reference value; and a drive amount correction stage for continuing to drive the conveyor belt in the second direction by a predetermined number of pulses even after the predetermined time has elapsed.

Effects> When the size and type of the document changes, variations occur in the driving amount even if the conveyor belt is driven in the second direction for a certain period of time.

Therefore, the above-mentioned variations due to the type and size of the document are detected by counting the number of pulses output from the pulse output means, and based on the detection result, the conveyor belt is additionally driven by a certain amount in the second direction. , so that the edge of the document coincides with a predetermined reference line.

<Embodiment> FIG. 3 is a schematic sectional view for explaining the configuration of an automatic document feeding device according to an embodiment of the present invention.

This automatic document feeder 1 is installed on the top surface of the copying machine main body 2, and includes a paper feed section 3, a belt conveyance section 4, and a reversing section 5.
It is equipped with

The paper feed section 3 includes a document setting table 6, a document setting detection switch 7 for detecting that a document has been set on the document setting table 6, a forward feeding recolo 8 for feeding the document, and a double feeding device. Paper feed roller 9 for feeding documents one by one while preventing
and a pair of reversing rollers 10, and a pair of registration rollers 11 for feeding the original to the belt conveyance section 4 at a constant timing.
and a document detection sensor 12 for detecting the document sent to the belt conveyance section 4.

The belt conveying section 4 is provided with a belt 13 for each document. The original plate 13 has a protruding edge that has a step with the surface of the contact glass 14 disposed on the top surface of the copying machine main body 2, and this edge forms a reference line 15 when setting the original on the contact glass 14. is forming.

The belt conveyance unit 4 further includes a conveyor belt 16, a pulse output switch 17 that outputs a pulse in conjunction with the drive of the conveyor belt 16, and a paper discharge tray 18 disposed above the conveyor belt 16. ing. This paper output tray 1
Reference numeral 8 denotes a tray from which the original, on which a one-sided copy has been made, is discharged.

The reversing unit 5 includes one transport switch for detecting the original sent out from the belt transport unit 4, an original reversing roller 20, and a switch for refeeding the original reversed by the original reversing roller 2o to the belt transport unit 4. , a document detection sensor 21 for detecting the leading edge of the document, and a paper output tray 2.
2 is provided. This paper ejection tray 22 is a tray on which originals, on which both the front and back sides have been copied, are ejected.

Note that a switching claw (not shown) is arranged in connection with the reversing roller 20, and the destination of the document can be switched by the switching claw.

FIG. 4 is a block diagram showing part of the electrical configuration of the control section of the automatic document feeder 1 according to this embodiment. Fourth
The figure shows only the parts necessary for the control operation that is a feature of this embodiment, which will be described later.

The electrical configuration includes a CPU 23 as a control center and a C
It includes a memory 24 connected to the PO 23 and a belt motor 25 to which a drive control signal is given from the CPU 2B. Further, the output of the document detection sensor 12 and the output of the pulse output switch 17 are provided to the CPU 23 .

The memory 24 includes a CPRUN area, a CPSET area, a timer 1 area, a timer 2 area, a timer 3 area, and a counter area necessary for control to be described later.

FIG. 1 is a diagram showing details of drive control of the belt motor 27 in the automatic document feeding apparatus 1 having the configuration shown in FIGS. 3 and 4. As shown in FIG. Further, FIG. 2 shows the drive control details of the conventional PELTOMO drive for comparison with the control details shown in FIG. 1.

Furthermore, FIG. 5 shows a flowchart of control operations executed by the CPU 23 of FIG. 4.

The flowchart in FIG. 5 is for executing the control contents shown in FIG. 1.

Next, in accordance with the flow shown in FIG. 5, and with reference to FIGS. 1 to 4, control operations that are characteristic of the automatic document feeding apparatus 1 according to this embodiment will be explained.

When the paper feeding section 3 starts feeding out the document and the document being fed into the belt conveying section 4 is detected by the document detection sensor 12, a detection output is given to the CPU 23. In response,
The CPU 23 gives a normal rotation drive signal to the belt motor 25 (
In step S1), the belt motor 25 is rotated in the forward direction, and the belt motor 25 causes the conveyor belt 16 to convey the document from the paper feed section 3 toward the reversing section 5.

The CPU 23 provides a normal rotation drive signal to the belt motor 25, and at the same time decrements the count value preset in the CPRUN area of the memory 24 (
Step S2), the belt motor 25 is rotated in the forward direction until the count value becomes "0". And the count value is “
0'' (step S3), timer 1 is started (step S4). Timer 1 is a timer that measures a predetermined period of time, for example 10 n+sec. Until this timer 1 times up, CPU2
3 applies a brake to the belt motor 25 (steps S5 and S6).

Further, while applying the brake to the belt motor 25, the CPU 23 counts the number of pulses X given from the pulse output switch 17 (step S7).

When the timer 1 times up, the CPU 23 gives a reverse drive signal to the belt motor 25 (step S white) and starts the timer 2 (step S9). Timer 2 is
A predetermined time, for example 25 m5ec, is measured.

The CPU 23 then controls the number of pulses X given from the pulse output switch 17 until the timer 2 times up.
is counted (step 511).

That is, the number of pulses X output from the pulse output switch 17 is counted during the total time Tfflsec of the brake signal output time to the belt motor 25 and the subsequent inverted drive signal output time in FIG. .

In this way, when giving a reverse drive signal to the belt motor 25, it is managed by time, and the pulse output switch 17 outputs a pulse within that time (in this embodiment, including the brake signal output time). The feature of this embodiment is that the number X is counted.

Controlling in this way has the following advantages.

That is, as shown in FIG. 1, when a forward rotation drive signal t= is output to the belt motor 25, a brake signal is applied, and a reverse drive signal is further applied, the conveyor belt 16 driven by the belt motor 25 is The belt motor 25 does not stop or reverse without any time lag in response to each signal applied to the belt motor 25, but rather stops and reverses with a certain time lag. This time lag varies depending on the size and type of the document conveyed by the conveyor belt 16. This is because, as described above, when the size of the document changes, the force required to drive the conveyor belt 16 changes.

Therefore, the document conveyed by the conveyor belt 16 rotates from normal rotation (the first movement direction in which it moves from the sheet feeding section 3 to the reversing section 5 in FIG. 3) to reversing (moves from the reversing section 5 to the direction of the sheet feeding section 3). The stopping position A of the trailing edge of the document in the second moving direction) varies depending on the size and type of the document.

If the stop position A varies, the document will stop if it is managed based on the number of pulse outputs when giving a reverse drive signal to the belt motor 25, as in the conventional control shown in FIG. It was not possible to deal with variations in position, and ultimately it was not possible to stop the trailing edge of the document so that it coincided with the reference line 15.

Therefore, in this embodiment, when giving a reverse drive signal to the belt motor 25, it is managed by time, and the actual movement amount of the conveyor belt 16 within that time is given from the pulse output switch 17. This was determined by the number of pulses.

In other words, a certain period of time T (total time of timer 1 + timer 2)
The actual movement amount of the conveyor belt 16, in other words, the variation in the stop position A can be detected by the number of pulses output within the range. Specifically, when the document size is small, the contact area between the conveyor belt 16 and the contact glass 14 is large, so the amount of movement of the conveyor belt 16 is small, and the stop position A shifts to the left in FIG. However, when the document size is large, the stop position A shifts to the right. This amount of deviation is proportional to the number of pulses given from the pulse output switch 17.

Therefore, in step S12 in FIG.
Step 3 is to find the difference between the counted pulse number
- and adds it to CPSET to calculate CPSET- (step 513).Then, even after the timer 2 has timed up, the timer 2 continues to give a reverse drive signal to the belt motor 25,
During this time, each time a pulse is applied from the pulse output switch 17, the value of CPSET- is decremented, and when CPSET- reaches "0" (step S14
．． 515), start timer 3 (step 5
16).

In this way, in steps S14 and S15, the stop position A
Since a reversal drive signal is subsequently applied to the separating belt motor 25 in consideration of variations in the document size, even if the stop position A varies depending on the size of the document, the adverse effects caused by this variation can be eliminated.

Then, a certain period of time determined by timer 3, for example 20
Give a brake signal to the belt motor 25 during m5ec (
Step 517. 518), and the belt motor 25 is turned off (step 819).

Note that in step S12, the time set by the timer 2 is normally set so that X>N. Therefore, even if timer 2 times up, the correction amount will always remain and CPSET- will never become a negative value.

Further, during brake control in step S5 and step S near, it is preferable to short-circuit both terminals of the belt motor 25 by grounding them, since higher braking force can be obtained than by opening both terminals.

<Effects of the Invention> Since the present invention is configured as described above, the original can be reliably set at a predetermined setting position even if the size or type of the original is different.

Further, when the document is switched back by the conveyor belt, since the conveyor belt does not convey the document more than necessary, there is no need to worry about the edge of the document being bent.

Furthermore, since there is no need to add new elements to the conventional device, the present invention can be realized without increasing costs.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a control operation that is a feature of a device according to an embodiment of the present invention. FIG. 2 is a diagram showing the control operation of a conventional device for comparison with FIG. 1. FIG. 3 is a schematic sectional view showing the configuration of an embodiment of the present invention. FIG. 4 is a block diagram showing a partial configuration of an electric circuit necessary for control operation in an embodiment of the present invention. FIG. 5 is a flowchart showing control operations in one embodiment of the present invention. In the figure, 1... automatic document feeder, 2... copying machine main body, 3... paper feed section, 4... belt conveyance section, 5...
...Reversing section, 10... Document detection sensor, 15... Reference line, 16... Conveyance belt, 17... Pulse output switch, 23... CPU, 24... Memory, 25...
...Indicates a belt motor.

Claims (1)

[Claims] 1. Place the original to be set in the specified position on the transport bench. automatic document feeder, such as one that is transported by A sending device, Pulses are generated in conjunction with the drive of the conveyor belt. a pulse output means for outputting; The conveyor belt is moved to the first side by a predetermined amount. After driving in the first direction, the first direction is opposite to the first direction. The conveyor belt is driven in the second direction for a certain period of time. a belt drive means for The conveyor belt is driven in the second direction. is output from the pulse output means within a fixed time. pulse counting means for counting the number of pulses generated; The count value of the pulse counting means is determined in advance. a comparison means for comparing with the reference value determined; Based on the output of the comparison means, the said constant Even after the time has elapsed, the pulse continues to be delivered for the predetermined number of pulses. Drive amount to drive the feed belt in the second direction a correction means; An automatic document feeder characterized by comprising: Place.