JPH06255840A - Skew correcting method - Google Patents

Abstract

PURPOSE:To provide a skew correcting method wherein high accurate skew decision can be performed even when generated an error of a mounting position in an optical sensor of a skew detecting mechanism. CONSTITUTION:In a skew detecting mechanism, three optical sensors are arranged on a straight line in a vertical direction to a direction of conveying a cutform in a conveying path, to detect a skew amount by a detecting time difference of the optical sensors. Amounting position error of the optical sensor, detecting this skew amount, is measured and corrected, to decide a skew, and it is corrected. A time difference of each optical sensor is held (202) and corrected (203) by a previously measured registered optical sensor mounting position error. Here, a skew amount corrected in accordance with a skew with the right up or down is compared with a decision reference value (204) and corrected. Accordingly, skew detection of higher accuracy can be embodied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a skew (skew) correction method for an apparatus for printing on a single-cut sheet, and more particularly to a skew correction method for determining the presence / absence of a skew in consideration of an error in a skew detection sensor mounting position.

[0002]

2. Description of the Related Art Conventionally, in an apparatus for automatically printing and feeding cut sheets, printing is performed at a predetermined position of the cut sheets, and therefore skew of the cut sheets is detected during conveyance. We are making corrections. For example, in the method disclosed in Japanese Patent Laid-Open No. 60-229185, the skew determination is performed by comparing the value itself read by the optical sensor with the skew determination reference value. Was not considered.

[0003]

In the above-mentioned prior art, the skew detection is performed by comparing the information read by the optical sensor with the skew judgment reference value. There is a possibility that the skew judgment may differ depending on the An object of the present invention is to solve the above problems and provide a skew correction method capable of performing skew detection / correction with high accuracy even if an error occurs in the mounting position of the optical sensor of the skew detection mechanism. To do.

[0004]

In order to achieve the above object, the skew correction method of the present invention is a means for automatically feeding a single-cut sheet from a hopper and carrying it by a carrying roller to a printing section (the pulse shown in FIG. 2). (Motor 1 etc.) and means for detecting the skew of a single sheet being conveyed (skew detection mechanism 4)
In a single-cut printing apparatus having a means for storing the detection result and determining the presence or absence of skew (control section), and means for performing skew correction (skew correction mechanism 3 etc.), the skew detection is performed before actual operation. The mechanism measures the amount of skew of the standard paper that is set in the transport path without skew, and stores this in the nonvolatile memory as the mounting position error of the optical sensor of the skew detection mechanism. A skew correction method characterized by correcting the skew amount obtained during actual operation, and comparing the corrected skew amount with a skew determination reference value to determine the presence or absence of skew.

[0005]

According to the present invention, even if an error occurs in the mounting position of the optical sensor of the skew detecting mechanism, the skew determination is performed by the skew amount corrected for the error in the mounting position of the optical sensor at the time of skew determination. Skew detection and correction can be performed.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a mechanical configuration diagram of a single-cut sheet printing apparatus having a skew correction mechanism according to an embodiment of the present invention. In FIG. 2, 1 and 2 are pulse motors, 3 is a skew correction mechanism, and 4
Is a skew detecting mechanism, 5 is a printing unit, 6 is a hopper for storing cut sheets, and 7 is a clutch. This pulse motor 1
Is driven to rotate the roller of the conveying path, so that the single-cut sheet is fed from the hopper 6. In addition, the pulse motor 2 drives the rollers of the horizontal conveyance path to move the single sheet from the vertical conveyance path to the skew correction mechanism 3 and skew detection mechanism (optical sensor)
4. Transport to printing unit 5. In addition, the skew correction mechanism 3
When the clutch 7 is turned off, only the roller of the skew correction mechanism 3 is rotated in the direction opposite to the transport direction without rotating the roller in front of the correction mechanism 3 and the deviation (skew) of the leading edge of the cut sheet is detected. Make a correction. Further, the skew detection mechanism 4 has three optical sensors arranged in a straight line in the transport path in a direction perpendicular to the single-sheet transport direction A, and detects the skew by the detection time difference of the optical sensors. In addition,
The presence / absence of skew is determined by the detected / corrected skew amount by a control unit (not shown).

FIG. 3 is a block diagram showing the electric construction of a single-cut sheet printing apparatus having a skew correction mechanism according to an embodiment of the present invention. In the present embodiment, the detection information of the optical sensor 4 is read by the microprocessor (the control unit) 8 through the sensor reading circuit 11. The clutch 7 is a clutch control circuit 10, and the pulse motors 1 and 2 execute instructions of the microprocessor 8 by the pulse motor control circuits 9 and 12, respectively.

Now, the skew detection method of this embodiment will be described. FIG. 4 is a diagram showing a skew detection method according to an embodiment of the present invention. In FIG. 4, S1 to S3
Optical sensor, a ₁ ~a ₃ is detection time difference storage area of each S1 to S3, the detection time difference t ₁ is S2 and S3, t ₂ denotes the detection time difference between S1 and S3. The skew detection mechanism of the present embodiment is a mechanism in which three optical sensors are arranged in a straight line in the direction perpendicular to the transport direction A and the time difference between the optical sensor detections is used as the skew amount. Then, a detection time difference storage area is set for each of the three optical sensors, and "FF" is stored as an initial value in this area. Of the three optical sensors, "0" appears in the storage area of the sensor that detects the first cut sheet.
0 "is stored and used as a reference sensor. Then, the counting of time is started at this point, and then the time counted when the other two optical sensors detect a single slip is stored in the storage area of that sensor. to. If upward-sloping skew as shown in FIG. 4 is generated, become a skew reference is S3, S1, S2 area a _1, detection time difference t ₂ between S3. a _2, t ₁ each is stored. all where S1~S3 cases are detected noncontinuous, the skew amount of noncontinuous the detection time difference between S1 and S3. Accordingly, and t ₂ is a skew amount in the case of FIG. 4 Become.

Finally, a method for measuring the mounting position error of the optical sensor and a method for determining the presence / absence of skew will be described. FIG. 1 is a flowchart showing a skew correction method according to an embodiment of the present invention. In FIG. 1, (a)
Shows a method of measuring an optical sensor mounting position error of the skew detecting mechanism, and FIG. 9B shows a method of skew correction by correcting the mounting position error to perform skew determination. In this embodiment, when measuring the mounting position error of the optical sensor, as shown in (a), the fixed form sheet is sent out to the conveying path before the actual operation and conveyed to the skew detecting mechanism while keeping the skew-free state ( Step 101).
When the sheet is detected by the skew detection mechanism (step 102), the detection time difference of each optical sensor shown in FIG. 4 is registered in the nonvolatile memory (step 103), and the sheet is ejected (step 104). Further, in the case of performing skew determination and correction by utilizing the detection time difference (optical sensor mounting position error) registered in this way, when the skew detection mechanism detects a single slip during actual operation, as shown in (b), 201), the detection time difference of each optical sensor shown in FIG. 4 is held (step 202), and this is corrected by the optical sensor mounting position error measured and registered in advance in the procedure of (a) (step 203). At this time, it is checked whether or not the reference sensor for the skew detected this time and the reference sensor for measuring the optical sensor mounting position error match. As a result, when both reference sensors match, the mounting position error is subtracted from the optical sensor detection time difference obtained in step 202. If the reference sensors do not match, step 2
Correction is performed by adding the mounting position error to the optical sensor detection time difference obtained in 02. This is to correct the detection time difference (skew amount) according to the skew to the right or to the bottom. The skew amount thus corrected is compared with the skew determination reference value to determine the presence or absence of skew (step 204). As a result, when it is determined that there is skew (step 205), the skew correction mechanism corrects the sheet conveyance direction (step 206).

[0010]

According to the present invention, even if the optical sensor of the skew detecting mechanism has a mounting error, the skew can be determined in consideration of the sensor mounting position error measured before the actual operation. Highly accurate skew detection can be performed.

[Brief description of drawings]

FIG. 1 is a flowchart showing a skew correction method according to an embodiment of the present invention.

FIG. 2 is a mechanical configuration diagram of a single-cut sheet printing apparatus having a skew correction mechanism according to an embodiment of the present invention.

FIG. 3 is a block diagram showing an electric configuration of a single-cut sheet printing apparatus having a skew correction mechanism in one embodiment of the present invention.

FIG. 4 is a diagram showing a skew detection method according to an embodiment of the present invention.

[Explanation of symbols]

 1 pulse motor 2 pulse motor 3 skew correction mechanism 4 skew detection mechanism (optical sensor) 5 printing unit 6 hopper 7 clutch 8 microprocessor 9 pulse motor control circuit 10 clutch control circuit 11 sensor reading circuit 12 pulse motor control circuit

Claims (1)

[Claims] 1. A means for automatically feeding out a single-cut sheet from a hopper and conveying it to a printing unit by a conveying roller, a means for detecting a skew of the single-cut sheet being conveyed, and a presence / absence of skew by storing the detection result. In a skew correction method for a single-cut sheet printing apparatus having a means for determining the skew and a means for performing skew correction, the skew detecting means is used before actual operation,
It is characterized in that the mounting position error of the skew detection sensor is measured and stored, the skew amount obtained during actual operation is corrected by the mounting position error, and the presence or absence of skew is determined from the corrected skew amount. Skew correction method.