JPH01214555A - Medium carrying mechanism - Google Patents

Abstract

PURPOSE:To detect skew quantity of medium for making it possible to correct skew in correspondence to skew quantity by counting difference in time or medium carrying quantity detected about medium by two sensors. CONSTITUTION:When it is detected that medium 1 carried in accordance with a program in a memory 14 reached to on a sensor 4 with a medium detecting circuit 11, a CPU 10 orders a counter 13 to start counting on carrying step numbers by a step motor 3a or 3b. Still, when it is detected that, on being sent, the medium 1 reached a position on a sensor 5 with the medium detecting circuit 11, the CPU 10 judges whether carrying of medium 1 is of normal or not on comparing counted value on the counter 13 with a set value within the memory 14. If the carrying is normal, the same sends order to a medium driving circuit 12 so as to continue carrying. When it is abnormal, the same send order to the medium driving circuit so as to carry in only regulated time on changing rotation speed of the step motor 3b in accordance with a program within a memory 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a medium transport mechanism, and more particularly to a medium transport mechanism capable of detecting skew (hereinafter referred to as skew) of a medium and correcting the skew.

[Prior art]

In printers and optical character recognition devices (hereinafter referred to as OCR devices) that are equipped with a mechanism for transporting media such as paper sheets, it is important to keep the skew of the media below the allowable amount in order to ensure the quality of the device. be.

For example, in a printing device such as a printer, when a printing medium is conveyed in a skewed state and printing is performed, not only is the printing not performed at the correct position, but also the printing occurs outside the medium. In such a case, the printed content becomes unclear.

Furthermore, if the printing means is a wire dot head and the medium is thick such as cardboard or a bankbook, the wire of the head may catch on the side of the medium, causing the wire to break and damage the apparatus.

In addition, in reading devices such as OCR devices, the reading area is generally determined, so if the medium is conveyed in a skewed manner, the reading sensor may move out of the reading area, or the reference side for OCR recognition may become tilted. This significantly deteriorates the reading quality, such as making it unrecognizable.

For this reason, various proposals have been made to prevent the medium from being conveyed in a skewed manner.

For example, in the method described in Japanese Patent Application Laid-Open No. 62-87370, one sensor near the side edge of the medium is used to transport the medium a certain distance and then detect the presence or absence of the medium on the sensor. Then, the skew of the medium is checked, and the conveyance of the skewed medium is stopped and a retry is performed.

[Problem to be solved by the invention]

The above-mentioned conventional technology is effective when the medium is conveyed by guiding its side edges. For example, as shown in FIG.
In a device in which the sensor 24 detects the medium 21 sent to the medium 21, the skew in the direction shown by the solid line can be detected.

However, when the medium is transported without being guided by its side surfaces, the medium may also be skewed in the direction shown by the dashed line in FIG. In this case, skew cannot be detected.

Further, after detecting a skew in a medium, it is necessary to eject the medium and retry. Normally, in the case of a retry, the operator takes out the ejected media and reinstalls it.
This complicates the operator's operations and reduces the throughput of the device.

Furthermore, devices with automatic paper feeding mechanisms generally process media continuously, and it is difficult to eject the media sucked into the device to the insertion side during continuous processing, so detected skewed media cannot be processed. It is discharged to the discharge side. but,
In a reading device such as an OCR device, unprocessed media are mixed in with a large amount of read media at the output side, and it takes a lot of time to search for unprocessed media, and there is also a risk of omission of processing. As a solution to this problem, it may be possible to provide an outlet for the skewed medium, but this would require a new gate to switch the conveyance path, which would complicate the structure.
There is a problem that the device becomes larger.

Further, as a method for correcting the skew, it is possible to provide an abutting surface against which the medium side end abuts the conveyance path, and forcibly press the medium side end against the abutting surface. This method is effective for stiff media such as passbooks and cardboard, but when using thin paper, there is a problem in that the paper may bend or warp, causing jams.

The purpose of the present invention is to improve such problems, detect the skew of the medium being conveyed, and to detect the skew of the medium being conveyed.
It is an object of the present invention to provide a medium transport mechanism that can automatically perform skew correction and maintain good transport accuracy without reducing processing capacity.

[Means to solve the problem]

In order to achieve the above object, the medium conveyance mechanism of the present invention includes a medium conveyance direction and a plurality of independently driveable medium conveyance means (conveyance rollers or conveyance belts) located facing each other in a direction perpendicular to the conveyance direction. and a plurality of sensors that are located at a distance in the medium transport direction and in a direction perpendicular to the transport direction on the medium transport path and detect the presence or absence of the medium. A means (counter) for counting either the time difference when at least two of the plurality of sensors detect the medium or the difference in the amount of medium conveyance, and the count value is within a preset tolerance range. If it is outside the range, it is determined that the medium is largely skewed, and according to the count value, means (CPU) independently controls the conveyance speed of the plurality of medium conveyance means, and the CPU determines that the medium is largely skewed. If the value is outside the allowable range, the medium is conveyed while correcting its inclination by independently changing the conveyance speed of the medium conveyance means located facing each other according to the count value.

[Effect]

In the present invention, the amount of skew of the medium is detected by calculating the time difference between the two sensors detecting the medium or the difference in the amount of conveyance of the medium, and according to the count value,
Skew correction is performed by rotating the medium by the skew amount in a direction that eliminates the skew amount by changing the feed amount of both ends of the medium using the conveyance roller or conveyance bell 1- that conveys the medium. This is the time it takes for another sensor to detect the medium after the medium passes through one sensor in the medium conveyance path, or the amount of conveyance of the medium, which is determined by the amount of skew (angle of inclination of the medium) of the medium. By being a function.

〔Example〕

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

FIG. 3 is a configuration diagram of the medium transport mechanism in the first embodiment of the present invention.

The medium conveyance mechanism of this embodiment has a conveyance roller of 2 degrees.

2b, step motor 3゜+Jb, and sensor 4゜5
Equipped with.

This conveyance roller 2°+2b conveys the medium in the direction of arrow A. Further, the conveying rollers 2°+2b are independently driven and rotated by step motors 3°+3b via drive transmission means (not shown) such as gears or belts.

Further, on the medium conveyance path, sensors 4 and 5 for detecting the presence or absence of the medium 1 are installed at a distance M in the medium conveyance direction and as far apart as a distance in a direction perpendicular to the medium conveyance direction.

In such a configuration, the conveyance amount of the medium 1 per step of the step motors 3° and 3b is S, and the inclination angle of the medium 1 is α.
Then, when the medium 1 is conveyed at an inclination α, the step motor 3 degrees until the sensor 4 detects the medium 1 and the sensor 5 further detects the medium 1.

The number of steps n in step 3b is expressed by the following equation (1,).

(1) n= (M-Ltanα) /S With this,
By converting the number of steps n to medium]-
It is possible to detect the inclination angle α.

Furthermore, the number of steps n□ of the step motors 3° and 3b when the allowable inclination angle of the medium 1 is ±α'.

By setting n2 in advance in the memory 14 (see Figure 1), if (2) n-work≦n≦02 holds true, the inclination of the medium 1 is within the permissible range and the conveyance is normal. I can judge.

Also, if this n1≦n≦n2 does not hold, the medium]
- The skew amount is large, and it is determined that the conveyance is abnormal.
Perform skew correction.

For this skew correction, the conveyance roller 2°.

Assuming that the distance 2b is &R, the difference P in the conveyance amount between the two conveyance rollers and the position 25 when the medium 1 is conveyed with an inclination of α is expressed by the following equation (3).

(3) P=Rtanα Therefore, when correcting the inclination α of the medium 1, the conveyance roller with the smaller conveyance amount should be rotated more by P, or the conveyance roller with the larger conveyance amount should be rotated by P less. Bye.

For example, the rotational speed m(p
ps), the amount of transport in seconds is t-8-m. Thereby, in order to correct the skew in seconds, the media 1 is transferred to the transport roller 2 in seconds.
It is conveyed by t-8-m at
-m-P). In other words, step motor 3. The rotation speed of step motor 3b is (t - S - m - P) / (t -
5) If (p p s) is driven and rotated for seconds, the skew is corrected.

FIG. 4 is a flowchart of medium conveyance in the second embodiment of the present invention.

In this embodiment, during conveyance of the medium 1, after the sensor 4 detects the medium 1, the step motor 3. Count the number of driving steps of l or 3b (4
01-404).

Next, the Karan 1-value n is compared with a preset value to determine whether the skew amount of the medium 1 is within the allowable value (4
05).

If the result is within the allowable value, the transport continues (4
09).

If it is outside the allowable value, the rotation speed of the step motor 3b is changed to the specified rotation speed according to the count value n (40
6), the skew amount is corrected by conveying for a specified time (407, 4.08).

After correcting the skew amount in this way, the rotational speeds of the step motors 3° and 3b are made the same and conveyance is continued (4
09).

FIG. 1 is a schematic configuration diagram of a control circuit of a medium transport mechanism in a first embodiment of the present invention.

The control circuit in this embodiment is a CPU that controls each circuit.
10, a medium detection circuit 11 that detects the presence or absence of a medium by detecting information from the sensors 4 and 5; and a step motor 3, . 3b, a step motor 3°, a counter 13 for counting the number of steps of 3b, and a memory 14 for storing a program for controlling the medium.

With such a configuration, when it is detected by the medium detection circuit 11 that the medium conveyed according to the program in the memory 14 has come onto the sensor 4, the CPU 10 causes the counter 3 to initiate the conveyance step of the step motor 34 or 35. Command to start counting.

Further, when the medium detection circuit 11 detects that the medium 1 has been conveyed and has come onto the sensor 5, the CPU 10 compares the count value of the counter 13 with the set value in the memory 14, and Determine whether it is normal or not.

If the result is normal, the CPU 10 sends a command to the medium drive circuit 12 to continue transport.

If there is an abnormality, the step motor 3. A command is sent to the medium drive circuit 12 to change the rotational speed of the medium and convey it for a specified time.

Thereafter, the rotational speeds of the step motors 3a and 3b are made the same, and the conveyance is continued.

Note that the rotational speed and conveyance time of the step motor 3b corresponding to the counter value n of the counter 13 are set in advance in the memory 14 so as to be appropriately corrected.

Further, in this embodiment, the conveyance means are conveyance rollers 2, I, 2.
b, but the conveyance roller 2. ．． Similar effects can be obtained when a conveyor belt is used instead of 2b.

Although skew correction was performed while conveying the medium 1 in the medium conveyance direction (six directions of arrows shown in FIG. 3), it is also possible to perform skew correction by reversing the conveyance rollers 2°+2b. In other words, step motor 3° + 3b
is reversed, and the step motor 3° is rotated (t -S -m-
P)/(t-8)(p p s), step motor 3b
may be rotated at m (pps) for t seconds, and then rotated again at the same rotational speed in the transport direction. In this case, the skew check can be performed again after the skew correction. Further, by conveying the medium 1 in the reverse direction, the length of the conveyance path necessary for skew correction can be omitted, so that the apparatus can be made smaller.

FIG. 5 is a configuration diagram of a medium transport mechanism in a second embodiment of the present invention.

The medium conveyance mechanism of this embodiment includes a conveyance roller 2°.

2b, step motors 3a, 3b, and sensors 4 to 7
This embodiment differs from the first embodiment in that four sensors are provided on the conveyance path.

This is because when detecting the amount of skew, the greater the distance between the sensor in the media transport direction and the direction perpendicular to the transport direction, the greater the detection accuracy, so the distance between the sensors is always the maximum for the media. The second reason is to improve the accuracy of skew detection by changing the sensor used depending on the width of the medium.

In other words, when the medium 14 with a width of 11 is conveyed, the sensor with the inter-sensor distance L□ (LL < il), the sensor 4
and sensor 5 to detect the amount of skew.

Further, when the medium 1b having a width of 1□ is conveyed, the skew amount is detected using sensors having an inter-sensor distance of L2 (L2<12.L<L2), that is, the sensor 4 and the sensor 6.

Further, when a medium having a width of 13 by 1° is conveyed, the skew amount is detected using sensors having an inter-sensor distance of L3 (r-3<13, L2<L3), that is, sensor 4 and sensor 7.

Note that control is performed by a program in the memory 14, as in the first embodiment (FIG. 1).

This allows the two sensors at the maximum distance to be selected for detection at all times depending on the width dimension of the medium.
The accuracy of skew amount detection can be improved.

〔Effect of the invention〕

According to the present invention, the amount of skew of the medium can be detected by counting the time difference between when two sensors on the medium conveyance path detect the medium or the difference in the amount of conveyance of the medium, and skew correction corresponding to the amount of skew can be performed. be.

Therefore, it is possible to provide a medium transport mechanism with high transport accuracy without significantly reducing the processing capacity for skewed media.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a control circuit of a medium transport mechanism according to a first embodiment of the present invention, FIG. 2 is an explanatory diagram of skew detection by a conventional medium transport mechanism, and FIG. FIG. 4 is a block diagram of the medium transport mechanism in the embodiment, and FIG. 4 is a flowchart of the medium transport in the first embodiment of the present invention.
The figure is a configuration diagram of a medium transport mechanism in a second embodiment of the present invention. ], 16-1c: Medium, 2, 1.2b, 22: Conveyance roller +3d+3b' step motor, 4-7, 24
．． : Distance between sensors: CPU, 11: Medium detection circuit,
12: Medium drive circuit, 13: Counter, 14: Memory. 1□～13. L, L□ to L3 Distance between the two sensors in the direction perpendicular to the medium conveyance direction 1M: Distance between the sensors in the medium conveyance direction, R: Distance of the conveyance roller, α: Inclination angle of the medium.

Claims (1)

[Claims] 1. A plurality of medium conveyance means that are located facing each other in a medium conveyance direction and a direction perpendicular to the conveyance direction and can be driven independently;
In a medium transport mechanism including a plurality of sensors that are located at a distance in a medium transport direction and a direction perpendicular to the transport direction on a medium transport path and detect the presence or absence of a medium, the plurality of sensors means for counting either the time difference when at least two detect the medium or the difference in medium conveyance amount, and a count value of the counting means;
means for determining that the inclination of the medium is abnormal if it is outside a preset range, and independently controlling the conveying speed of the medium conveying means located facing each other according to the count value; is outside the set range, the medium conveyance mechanism is characterized in that the conveyance speed of the medium conveyance means located facing each other is independently changed according to the count value, and the inclination of the medium is corrected and conveyed. .