JPS5863647A - Compensating method for feed error in paper feeder - Google Patents

Abstract

PURPOSE:To always keep the fed quantity of paper constant, by providing two secnsors which are located at a distance from each other in the direction of movement of the paper and detect its front end and by comparing the number of paper movement pulses with that of reference pulses to control the fed quantity of the paper. CONSTITUTION:A driving roller 3a and a driven roller 3b for paper 8, a pulse motor 5 for rotating the driving roller and a timing belt 7 are provided. Two sensors S1, S2 are provided at a prescribed distance of (b) from each other in the direction of movement of the paper 8 downstream to the feed rollers 3a, 3b to detect the front end of the paper. The number of reference pulses necessary to move the paper by the distance of (d) is set in the memory of a controller 14. The number of pulses actually cost to move the paper 8 from the sensor S1 to the other sensor S2 is compared with the set number of pulses to control the subsequently fed quantity of the paper.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of controlling a paper feeding device in a printer of an information processing apparatus, and relates to a method of correcting feeding errors for sheet-like paper.

A sheet of printing paper supplied to a printer is normally subjected to printing processing by being given line feed or other controlled paper feed by the frictional force of a feed roller. This feed roller is made of urethane rubber, and the amount of paper feed is controlled by the amount of rotation of this roller. The amount of paper feed corresponding to the amount of rotation of the roller changes due to roller wear and changes in the coefficient of friction, and this appears as a paper feed error.

For example, the coefficient of linear expansion of urethane rubber is about 2 x IQ - 4, and if the temperature changes by 40 degrees, when A4 size paper is fed vertically, the trailing edge of the paper will be about 3.4 mm long. A feed error occurs. In addition, the rollers include manufacturing errors of about 0.05 mm in diameter, so if a normally used roller with a circumference of 50.8 mm is used to feed A4 size paper in the vertical direction, A feed error of approximately 1.3 mm)/min occurs at the trailing edge of the paper.

Generally, in paper feeding devices using friction rollers, A4
When paper is fed vertically, the temperature changes due to temperature changes.
It must be taken into account that an error of approximately 4 mm will occur at the trailing edge of the paper due to production errors, wear and other factors of the rollers, and the paper feed device in conventional printers is Since no means had been taken to effectively correct the error, it was prohibited to add horizontal ruled lines in advance to a sheet of printing paper, and an extra margin was taken at the trailing edge of the paper.

However, documents without horizontal ruled lines have poor visibility and there is a risk of misunderstanding the written information, and if these horizontal ruled lines are printed on a printer, the load on the print head is likely to be excessive.
Printing speed also decreases significantly. Furthermore, in documents that are fed to a printer many times and new items are printed each time, such as various ledgers, the line position may shift each time the printing process is performed, resulting in very unsightly printing. There was a drawback.

It is an object of the present invention to solve these problems, that is, to provide an effective means for correcting the feeding error of sheet-like printing paper caused by the above-mentioned factors and always keeping the feeding amount constant. This was developed for the purpose of a paper feeding device in which the paper feeding amount is digitally controlled, that is, the number of pulses given to the paper feeding pulse motor or detected by a pulse generator attached to the roller drive system. This is applied to a paper feed device that controls the amount of paper feed based on the number of pulses.

The paper feed error correction method of the present invention is a paper feed error correction method in a sheet paper feed device in which the paper feed amount is digitally controlled. ) Two sensors for detecting the leading edge of the paper are provided at a predetermined distance apart in the paper running direction, and the reference number of pulses required to run the paper the predetermined distance is set in memory. The present invention is characterized in that the subsequent amount of paper feed is adjusted by comparing the number of pulses required for the paper to travel between the sensors when the paper is run at the set number of pulses. One of the two sensors can be used as is for detecting the beginning or initial position of the paper, so in order to adopt the method of this invention, only one sensor needs to be newly installed. Since the control procedure requires only a partial modification of the conventional control program, it can be implemented at an extremely low cost.

Hereinafter, further explanation will be given based on the embodiments shown in the drawings.

FIG. 1 is a side view of essential parts showing an embodiment of a paper feeding device using the method of the present invention. In the figure, 1 is the print head, 2
3 is a platen, and 3 is a feeder 90-ra consisting of a drive roller 3a and a driven roller 3b pressed against the drive roller 3a. The driving roller 3a is usually made of urethane rubber, and the driven roller 3b has a resin lobe to prevent printing ink from adhering to it. 4 is a pulley fixed to the shaft of the drive roller 3a, 5 is a pulse motor for driving the roller 3a, 6 is a pulley fixed to the shaft of the pulse motor 5, and 7 is a winding between the pulleys 4 and 6. It's a rotated timing belt. Sl and S2 are sheet-shaped paper to be supplied.
A sensor for detecting the leading edge of the paper 8, Sl is a sensor for detecting the beginning position of the paper 8, and S2 is a sensor added to carry out the method of the present invention. sensor S
1 and 82 are spaced apart by a predetermined distance d, and since this distance d serves as a reference amount for the paper feed amount, it must be set accurately. Note that N is the number of reference pulses required to travel the paper-8 by the set distance d.

9 to 13 are guide plates for guiding the paper 8; 14;
is a control device, and the broken line in the figure shows a control signal transmission path.

Control equipment manufactured by 14 companies controls the pulse motor 5 according to the control program shown in Fig. 3 (flowchart) to achieve %A.
For. Here, 8' v S '' tl is an output signal from the sensor S1.as in FIG. This means that the paper 8 does not exist at the position.M is a parameter that gives the actual number of pulses fc required to move the paper 8 by the distance d shown in Fig. 1, and J is a parameter for switching the control path. flag, D is a parameter that gives the amount of accumulated error in the paper feed amount at a certain point in time, and DD is a parameter that gives the amount of error in paper feed !7 that occurs every time the motor 5 is driven once. The value is set to 0.L is the number of pulses corresponding to the set print line spacing, and K is the actual number of pulses that the motor
is the number of pulses given to K, and K is the number of pulses given to
A value of either L+1 or L-1 is given. In addition, "drive pulse output 1" in FIG. 3 means that one drive pulse is given to the pulse motor 5, and "
"Line printing" is when the print head 1 performs a printing operation for one line.
It means. □ Next, an overview of the operation of the flowchart shown in FIG. 3 will be explained. When the paper 8 is fed, driving pulses are continuously applied to the pulse motor 5 until the paper 81 is turned on, that is, until the sensor S1 detects the leading edge of the paper 8, and the beginning of the paper 8 is performed (step 15 and 1B). Next, initial values are given to each parameter (step 17), and the first line is printed in step 18. During the beginning (until the leading edge of paper 8 is detected by sensor S2), D
Since the initial value of =0 is maintained, in step 19 the standard line leading F) /< /L/ is given to K, and steps 20 to 2 are applied until K becomes 0.
Line feed is performed by repeating step 6.

At this time, since the sensor S2 has not yet detected the paper 8, the number of drive pulses given to the pulse motor 5 is counted to M in step 23.

When the line feeding is completed, the process returns to step 36, and as long as print data exists, printing and line feeding are repeated through steps 18 to 26. And during this time/< Iv 7-E
: The number of drive pulses added to -1 will be integrated into the parameter M.

If at some point sensor S2 detects paper 8, the control path from steps 22 to 23 is immediately switched to the path from steps 22 to 27. Once the sensor S2 detects the paper 8, the sensor S2 will not be turned off until the paper 8 is ejected, so the control path will not pass through step 23 thereafter. Steps 24 and 2
Reference numeral 8 is added for an emergency stop when sensor S2 malfunctions for some reason or when paper 8 is fed diagonally and detached from sensor S2.

When the sensor S2 detects the leading edge of the paper 8, the feed error accumulated up to this point and the feed error J)1) per drive pulse are calculated in steps 29 to 31, and the flag J is set to 1. . If the actual feed amount of paper 8 is smaller than the specified feed amount, then M)N, so D and DI) will be positive values, and if the actual feed amount is larger than the specified feed amount, then l) and DD are negative values. After these have been calculated, D is changed by the value of DD every time a drive pulse is applied in step 25, so that D is always given the integrated value of errors at that point in time. After this D is calculated, the number K of line feed pulses is changed in accordance with the value of D each time the line feed operation in steps 20 to 26 is started. That is, if D is larger than 0.5, that is, if the actual feed amount of the paper 8 is smaller than the set feed amount by 0.5 pulses or more, in step 32, K is set to L+.
1 is given to increase the next line feed amount by one pulse more than the reference pulse number. Then, in step 33-, the value of D is previously subtracted by this one pulse. This is because at the time this changeover operation is completed, the accumulated feed error amount has been corrected by one pulse. Similarly, if the actual feed amount of paper 8 is greater than the set feed amount by 0.5 pulses or more, the next line feed amount is reduced by one pulse in step 34, and the next line feed amount is reduced by one pulse in step 35. Only D
The value of is corrected. Since the feed amount is not corrected until the paper 8 is detected by the sensor S2, a feed error of several pulses may have occurred when the leading edge of the paper 8 reaches the position of the sensor S2. , the error is corrected during the few line feeds after sensor S2 is activated, and then the paper is processed while correcting the number of line feed pulses so that the integrated error is maintained between plus or minus 0.5 pulses. 8 feedings will be performed. Therefore, the distance d between sensors S1 and 82
By choosing a distance that is not too large, it is possible to correct the accumulated feed error before it becomes too large. For example, in a paper feed device configured such that the distance d is 50.8 mm, which is the same as the circumference of the roller 3a, and the roller 3a rotates once with a driving pulse of 480 parnus, the temperature change of 40 degrees causes the position of the sensor S2 to change. The feeding error of the paper 8 that occurs before it comes is 0.4 mm! J
meters, and the difference between the number of pulses M and N at this time is 3.8 pulses, and this error is corrected during the subsequent 4-line feed operation, and thereafter the error is equivalent to 0.5 pulses. That is, the paper is fed with a feeding error within plus or minus 0.05 mm. When the printing example is finished, this is detected in step 38, and the paper 8
The pulse motor 5 is continuously driven until the rear end of the sheet 8 passes the position of the sensor S1, and the printing process for the sheet 8 is completed.

When implementing the method of the present invention in a feeding device in which the feed roller 3 is located upstream of the print head 1 as shown in FIG. 2, a cent St is provided immediately after the feed roller 3,
The feed error DD per drive pulse can be determined by the procedure described above with respect to the cue sensor S2. In this case, the position where the leading edge of the paper is detected by sensor S2 becomes the reference position, and since the cumulative feed error at this reference position is naturally 0, the line feed amount is corrected from the first line feed. This makes it possible to correct the paper feed amount more accurately than in the case of the paper feed device shown in FIG. 1 described above, and the control program thereof also becomes simpler.

As explained above, the present invention compares the actual number of pulses M required to run the paper for a certain set distance 6 with the reference number of pulses N, and corrects the paper feed amount after that. It is possible to accurately maintain the paper feed amount from the cue position or reference position by multiplying the
It reliably prevents feeding errors caused by temperature changes and roller wear, and it also prevents large print line misalignments at the rear edge of the printing paper, ensuring that printing is always done in the same position. Therefore, by using the method of this invention, it is possible to print horizontal ruled lines on sheet-like paper in advance, and the printing position on forms such as ledgers that are repeatedly printed is always maintained constant. This has the effect that printed forms with extremely good visibility can be obtained.

[Brief explanation of drawings]

FIG. 1 is a side view showing the main parts of an embodiment of a paper feeding device using the method of the present invention, FIG. 2 is a side view of the main parts showing another embodiment of the paper feeding device, and FIG. 3 is a flowchart showing a control procedure in the illustrated device. In the figure, 1 is a print head, 2 is a platen, 3 is a feed roller, 3a is a drive roller, 3b is a driven roller, 5 is a pulse motor, 7 is a timing belt, 8 is a sheet of paper, 14
is the control device, 81.82 is the sensor, d is the distance between the sensors,
N is the standard feed pulse number corresponding to dK, M is the actual feed pulse bush corresponding to d, D is the integrated value of feed errors, DD is the feed error per pulse, L is the reference line feed pulse number, K
is the corrected number of leading pulses. Agent Patent Attorney Takao Nishi Daiichi 14 Figure 2 Figure 31

Claims (1)

[Claims] (1) In a paper feeding device where the feed rate of a sheet of paper fed by a friction roller is controlled by the number of pulses applied to a pulse motor for driving the roller or the number of pulses detected by a pulse generator installed in the roller drive system. A feeding error correction method, wherein two sensors for detecting the leading edge of the paper are provided at a predetermined distance apart in the running direction of the paper on the downstream side of the friction roller, and the paper is made to run the predetermined distance. Set the reference number of pulses required for this in the memory, and then compare the number of pulses required to travel between these sensors when the paper is actually running with the set number of pulses. A method for correcting feeding errors in a paper feeding device, the method comprising increasing or decreasing the number of feeding pulses.