JPH1081432A - Image processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of defective printing by surely detecting the oblique running of documents and recording papers. SOLUTION: The transit time difference of the tip end part of each document, the transit time difference of the rear end part of each document and the difference in time required for each document to pass through respective paper size detection sensors 8a through 8n are computed by a document time difference computing part 122 based on the detected signal of each document from the paper size sensors 8a through 8n arranged over a line perpendicularly intersected with the document carrying direction. The difference in each computed time is compared with each threshold which is separately determined so as to be stored in a threshold memory part 2 by a document comparison part 123. And when any time difference is found to have exceeded the predetermined threshold, an warning that the document has not been normally carried out, is outputted by an error processing part 126.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus and, more particularly, to detection of a reading error and a printing error due to skew of a document and recording paper when reading a document and printing an image.

[0002]

2. Description of the Related Art In an image processing apparatus that conveys recording paper one by one and prints an image stored in an image information storage unit, normal printing may not be performed due to skew of the recording paper. Therefore, for example, a skew detecting device disclosed in Japanese Patent Application Laid-Open No. 7-112849 is provided with a first sensor and a second sensor for detecting a recording sheet on the same axis orthogonal to a recording sheet conveying direction near a recording position, If there is a difference in the time when the recording paper passes through both sensors, the presence or absence of skew of the recording paper is detected based on the time difference.

[0003]

However, the skew detecting apparatus detects skew by comparing the difference between the time when the recording paper passes through the first sensor and the time when the recording paper passes through the second sensor. The skew may not be detected depending on the state of the line and the sensor position. For example, when the recording paper is conveyed horizontally, even if skew occurs, both sensors may pass through the front side in the conveyance direction of the recording paper and the rear side in the conveyance direction, and in this case, the skew is detected. Can not.

Further, in the skew detecting device, since the sensor for detecting the recording paper is located near the recording position, the skew generated after the recording paper has passed near the recording position cannot be detected. Therefore, after the recording paper has passed the vicinity of the recording position, for example, before the fixing paper is fixed by the fixing device, the recording paper may be skewed, and the recording paper may be broken or broken. Is determined.

Further, since a sensor dedicated to skew detection must be provided, the configuration is complicated.

Further, in an image processing apparatus which conveys originals one by one and reads an image on the original, skew of the original cannot be detected.

SUMMARY OF THE INVENTION The present invention has been made to solve such a disadvantage, and an object of the present invention is to detect skew of a document and a recording sheet to reliably detect the occurrence of a printing failure.

[0008]

An image processing apparatus according to the present invention includes a time difference calculating section, a comparing section, and an error processing section,
The time difference calculation unit calculates the time when each paper size detection sensor detects the leading edge of the document based on the detection signals of the documents from at least two paper size detection sensors arranged in the range of the minimum document width on a line orthogonal to the document conveyance direction. The difference between the time required for each paper size detection sensor to detect the trailing edge of the document and the time required for the document to pass through each paper size detection sensor is calculated,
The comparison unit calculates the difference between the time when each paper size detection sensor calculated by the time difference calculation unit detects the leading end of the document, the difference between the time when each paper size detection sensor detects the rear end of the document, and the document passes through each paper size detection sensor. The error processing unit compares the time difference required to perform the operation with a predetermined threshold value, and if any of the time differences exceeds the predetermined threshold value as a result of the comparison by the comparison unit, the error processing unit performs the document conveyance correctly. A warning that the document has not been output is output, the skew of the document is reliably detected, and a warning is output.

The image processing apparatus has at least two recording paper detection sensors arranged in a range of a minimum recording paper width on a line orthogonal to the recording paper conveyance direction, a time difference calculating unit, a comparing unit, and an error processing unit. The time difference calculation unit calculates the difference between the time when each recording paper detection sensor detects the leading edge of the recording paper based on the signal from each recording paper detection sensor and the time when each recording paper detection sensor detects the rear end of the recording paper. The difference and the time required for the recording paper to pass through each recording paper detection sensor are calculated, and the comparison unit calculates the difference in the time calculated by the time difference calculation unit when each recording paper detection sensor detects the leading edge of the recording paper. Comparing the difference between the time when each recording paper detection sensor detects the trailing edge of the recording paper and the difference between the time required for the recording paper to pass through each recording paper detection sensor with a threshold individually determined in advance, The error processing unit does not recognize the result of the comparison If the time difference exceeds a predetermined threshold value, a warning indicating that the recording paper has not been properly conveyed is output, and the image data at that time is recalled from the image information storage unit to perform the printing process. In this manner, the skew of the recording paper is reliably detected, and the image having a printing failure is printed again.

The image processing apparatus has a time difference calculating section, a comparing section, and an error processing section. The time difference calculating section is provided with at least two recording paper position detecting sensors which are displaced in the recording paper conveying direction. Based on the recording paper position detection signal, a difference in time required for the recording paper to pass through each recording paper position detection sensor is calculated, and the comparing unit compares the time difference calculated by the time difference calculating unit with a predetermined threshold. However, if the difference between the time required to pass through each recording paper position detection sensor exceeds a predetermined threshold as a result of the comparison by the comparison unit, the error processing unit reports that the conveyance of the recording paper was not performed correctly. A warning is output, the image data at that time is recalled from the image information storage unit, and the printing process is controlled so that the skew of the recording paper is reliably detected, and the image having a printing failure is printed again. I do.

Further, the time difference calculation section calculates the time required for the recording paper to pass through each recording paper position detection sensor based on the signal from each recording paper position detection sensor, and the comparison section calculates the time required by the time difference calculation section. The time required for passing through each of the recording sheet position detection sensors is compared with a predetermined threshold value, so that skew can be detected at two places having different conveying speeds.

The time difference calculating section calculates the difference between the time when each recording paper position detection sensor detects the leading edge of the recording paper and the time when the trailing edge is detected, and calculates the difference based on the calculated two time differences. The comparison unit compares the difference between the detection time difference of the leading end of the recording paper calculated by the time difference calculation unit and the detection time difference of the trailing end of the recording paper with a predetermined threshold value.

Further, a recording paper position detection sensor is provided at two places which are displaced by a predetermined distance in the recording paper conveyance direction, and the time difference calculating section calculates the time during which each recording paper position detection sensor detects the recording paper. Then, the comparing unit compares the time calculated by the time calculating unit with a predetermined threshold.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image processing apparatus according to the present invention transports an original and a recording paper, each of which is formed of a fixed paper, such as a facsimile apparatus or a copying apparatus, one by one. This is to prevent a loss of image information by issuing a warning when the degree becomes larger than a predetermined degree or performing print processing again.

The image processing apparatus includes, for example, at least two paper size detecting sensors, a paper size detecting unit, a document conveying unit, a document reading unit, an image reading unit, which are provided in a range of a minimum document width on a line perpendicular to the document conveying direction. Information storage unit, time difference calculation unit,
It has a threshold storage unit, a comparison unit, and an error processing unit. The paper size detection unit detects the document size based on the output signal of each paper size detection sensor. The document transport unit transports the documents one by one to the document reading unit. The document reading unit reads an image on the document conveyed by the document conveyance unit based on the document size detected by the paper size detection unit, and stores image data of the read image in the image information storage unit.

The time difference calculating section calculates a difference between the time when each paper size detection sensor detects the leading edge of the document based on the signal from each paper size detection sensor, the difference between the time when each paper size detection sensor detects the rear edge of the document, and This is a part for calculating a difference in time required for a document to pass through each paper size detection sensor, and includes, for example, the same number of document width detection units and document length difference detection units as the paper size detection sensors. Each document width detection unit corresponds to each paper size detection sensor and one body, and the time when each paper size detection sensor detects the leading edge of the document, the time interval when each paper size detection sensor detects the document, and each paper size detection sensor The time when the trailing edge of the document is detected is detected. The document length difference detection unit detects each document based on the time when each paper size detection sensor detects the leading edge of the document, the time interval when each paper size detection sensor detects the document, and the time when each paper size detection sensor detects the rear edge of the document. The difference in the time when each paper size detection sensor detects the leading edge of the document based on the signal from the size detection sensor, the difference in the time when each paper size detection sensor detects the trailing edge of the document, and the document passes through each paper size detection sensor Calculate the difference in the time required to do so. Here, the reason for calculating the difference in the time when each paper size detection sensor detects the leading edge of the document is to detect skew occurring before the document arrives at the paper size detection sensor. The difference between the times when the trailing edge of the document is detected is calculated in order to detect the skew of the document that occurs after the leading edge of the document has passed each paper size detection sensor, and the document has passed each paper size detection sensor. The reason for calculating the difference in the time required to perform the operation is to detect a bent or skewed document. As described above, since the skew is detected based on the difference in the time when the leading edge of the document is detected, the skew can be reliably detected even when the document is conveyed horizontally.

The threshold storage unit stores, for example, a difference in time when each paper size detection sensor detects the leading edge of the document, a difference in time when each paper size detection sensor detects the trailing edge of the document, and a document passing through each paper size detection sensor. The threshold value is stored as a criterion of skew detection for each of the differences in the time required to perform the skew.
The comparison unit calculates the difference between the time when each paper size detection sensor calculated by the time difference calculation unit detects the leading end of the document, the difference between the time when each paper size detection sensor detects the rear end of the document, and the document passes through each paper size detection sensor. The difference in the time required to perform the comparison is compared with a threshold value stored in the threshold value storage unit in advance. Here, each time difference is compared with a predetermined threshold value, because even if skew occurs, the image information is not lost if the degree is small, so that in the case of slight skew, the conveyance is correct. This is to determine that the operation has been performed. The error processing unit displays a warning indicating that the document was not correctly conveyed when any time difference in the comparison result of the comparison unit exceeds a predetermined threshold, for example, on the operation display unit,
Output using a buzzer. Thus, when the document is not properly conveyed, the operator can easily know that the document has not been correctly conveyed, and by giving a read processing instruction to the document again, the loss of image information can be prevented.

The image processing apparatus may include, for example, an image information storage unit, a recording paper transport unit, a printing unit, and at least two recording paper detection units provided side by side in a range of a minimum recording paper width on a line perpendicular to the recording paper transport direction. It has a sensor, a time difference calculation unit, a threshold storage unit, a comparison unit, and an error processing unit. The image information storage unit stores, for example, image data of an image to be printed. The recording paper transport unit transports the recording paper one by one to the printing unit in accordance with the image to be printed. The printing unit reads out the image data from the image information storage unit and prints the image on the recording paper transported by the recording paper transporting unit.

The time difference calculating section detects the difference between the time when each recording paper detection sensor detects the leading edge of the recording paper based on the signal from each recording paper detection sensor, and each recording paper detection sensor detects the rear end of the recording paper. This is a part for calculating the difference between the time taken and the time required for the recording paper to pass through each recording paper detection sensor.For example, the same number of recording paper width detection units and recording paper length difference detection units as the recording paper detection sensors are used. Prepare. Each recording paper width detection unit corresponds to each recording paper detection sensor and one body, and the time when each recording paper detection sensor detects the leading edge of the recording paper, the time interval when each recording paper detection sensor detects the recording paper, and The time when each recording paper detection sensor detects the rear end of the recording paper is detected. The recording paper length difference detection unit detects the time at which each recording paper detection sensor detects the leading edge of the recording paper, the time interval at which each recording paper detection sensor detects the recording paper, and the time at which each recording paper detection sensor detects the trailing edge of the recording paper. The difference between the time when each recording paper detection sensor detected the leading edge of the recording paper based on the detected time, the difference between the time when each recording paper detection sensor detected the trailing edge of the recording paper, and the time when the recording paper detected each recording paper The difference in the time required to pass through the sensor is calculated. The comparison unit calculates the difference between the time when each recording paper detection sensor detects the leading edge of the recording paper calculated by the time difference calculation unit, the difference between the time when each recording paper detection sensor detects the rear end of the recording paper, and the recording paper. The difference in the time required to pass through the recording sheet detection sensor is compared with a predetermined threshold value. The error processing unit outputs a warning that the recording paper has not been properly conveyed when any of the time differences exceeds a predetermined threshold value in the comparison result of the comparison unit, and stores the image data at that time in image information. The recording paper transport unit and the printing unit are controlled so as to be called again from the unit and to perform the printing process.

Here, if the skew of the recording paper is detected at two places shifted in the recording paper conveyance direction, the skew of the recording paper can be detected more reliably, and for example, a recording paper position detection sensor can be used. Therefore, there is no need to provide a sensor dedicated to skew detection, and the configuration can be simplified. In this case, the time difference calculation unit calculates the time required for the recording paper to pass through each recording paper position detection sensor based on the signal from each recording paper position detection sensor, and passes the calculated recording paper position detection sensor. Calculate the difference in the time required to do so. The comparing section compares the recording paper position detection sensor passage time difference calculated by the time difference calculating section with a predetermined threshold value, and detects skew of the recording paper at two places separated in the recording paper transport direction.

Further, since the transport speed of the recording paper may vary depending on the position, the time difference calculating unit controls the recording paper to detect each recording paper position of the recording paper detection unit based on the signal from each recording paper position detection sensor. The comparing unit calculates the time required for passing, and the comparing unit compares the time required for passing through each of the recording sheet position detection sensors calculated by the time difference calculating unit with a predetermined threshold value, respectively, so that the conveying speed is different. The skew may be detected at two places.

The time difference calculating section calculates a time difference between the time when the recording paper position detecting sensor detects the leading edge of the recording paper and a time difference when the trailing edge is detected, and calculates the difference based on the calculated time differences. The comparing unit may compare a difference between the detection time difference of the leading end of the recording paper calculated by the time difference calculating unit and the detection time difference of the trailing end of the recording paper with a predetermined threshold value.

Further, a recording paper position detecting sensor is provided at two places shifted by a predetermined distance in the recording paper conveying direction, and the time difference calculating unit calculates the time during which each recording paper position detecting sensor detects the recording paper. The comparison unit may compare the time calculated by the time calculation unit with a predetermined threshold. Here, the predetermined distance is a distance that is slightly shorter than the length of the recording paper in the transport direction, and is a distance that can detect the length of the recording paper in the transport direction in relation to the transport speed of the recording paper.

[0024]

FIG. 1 is a block diagram of an image processing apparatus according to one embodiment of the present invention. As shown in the figure, a memory 1, a threshold storage unit 2, an image information storage unit 3, a document reading unit 4, a printing unit 5, an operation display unit 6, a line control unit 7, and paper size detection sensors 8a to 8 are provided.
n, recording paper detection sensors 9a to 9n, a document transport unit 10, a recording paper transport unit 11, and a main control unit 12. The threshold storage unit 2 stores in advance a threshold that is a reference for detecting skew and bend. Here, as the threshold value, for example, the difference between the time when each of the paper size detection sensors 8a to 8n detects the leading edge of the document,
The difference between the time when each of the paper size detection sensors 8a to 8n detects the trailing end of the original and the time when the original is
There is one for each of the differences in the time required to pass through n, and the threshold storage unit 2 stores these for each recording paper size, for example. The image information storage unit 3 stores image data of an image read by the document reading unit 4 and image data received from an external facsimile machine (not shown) via the line control unit 7. The document reading unit 4 reads an image from a document transported by the document transport unit 10. The printing unit 5 reads out image data from the image information storage unit 3 and prints an image on the recording paper transported by the recording paper transporting unit 11. The operation display unit 6 inputs a copy instruction, a facsimile transmission instruction, and the like, and displays the operation status. The line control unit 7 is, for example, a PSTN
The line is controlled, and facsimile communication with an external facsimile device (not shown) is performed.

The paper size detection sensors 8a to 8n are provided, for example, in the vertical direction of the document transport direction A upstream of the document reading unit 4 as shown in FIG.
Outputs a detection signal of the conveyed document. The recording paper detection sensors 9a to 9n are sensors including, for example, leaf switches. Each of the recording paper detection sensors 9a to 9n is arranged in the recording paper transport path 114 in the vertical direction of the recording paper transport direction B at a position facing the paper feed roller 113 as shown in FIG. Outputs a detection signal. The document transport unit 10 includes transport rollers 101 and the like, and transports documents one by one to the document reading unit 4. Recording paper transport unit 1
Reference numeral 1 denotes a paper feed roller 113 and the like, and conveys recording paper to the printing unit 5 one by one in accordance with printing by the printing unit 5.

The main controller 12 controls the entire image processing apparatus. Further, as shown in FIG. 4, the main control unit 12 includes a clock generation unit 121, a document time difference calculation unit 122, a document comparison unit 123, a recording paper time difference calculation unit 124, a recording paper comparison unit 125, an error processing unit. 126 and a paper size detection unit 127. The clock generator 121 outputs a clock signal which is a reference for the detection time of the document width. The document time difference calculation unit 122 includes document width detection units 21 a to 21 n and a document length difference detection unit 22. Each document width detector 21a-
21n corresponds to each of the paper size detection sensors 8a to 8n and one body 1, and for example, as shown in FIG.
a to 8n when the leading edge of the recording paper is detected, and the time interval T during which each paper size detection sensor 8a to 8n detects the original.
₁ g, T ₂ g and each paper size sensors 8a~8n detects time that has detected the trailing edge of the document portion. Time document length difference detecting unit 22 to the respective paper size detection sensor 8a~8n detects the original tip, the time interval each paper size sensors 8a~8n has detected the document T ₁ g, T ₂ g and each paper size detection The difference ΔTgf between the time when each of the paper size detection sensors 8a to 8n detects the leading edge of the document based on the time when the sensors 8a to 8n detect the trailing edge of the document, and the time when the paper size detection sensors 8a to 8n detect the trailing edge of the document. The difference ΔTgb in the detected time and the difference ΔT in the time required for the document to pass through each of the paper size detection sensors 8a to 8n.
Calculate Tg. The document comparison unit 123 is provided with each of the paper size detection sensors 8a to 8n calculated by the document time difference calculation unit 122.
Is the difference between the time when the leading edge of the document is detected, the difference between the time when each paper size detection sensor 8a to 8n detects the rear edge of the document, and the time required for the document to pass through each paper size detection sensor 8a to 8n. Each difference is compared with a threshold value stored in the threshold value storage unit 2 in advance.

The recording paper time difference calculating section 124 has the same number of recording paper width detecting sections 23a to 23n as the recording paper detecting sensors 9a to 9n.
n and a recording paper length difference detection unit 24. Each of the recording paper width detection units 23a to 23n corresponds to one of the recording paper detection sensors 9a to 9n, and corresponds to the time when each of the recording paper detection sensors 9a to 9n detects the leading end of the recording paper. 9n recording sheet detected and has a time interval T ₁ k, T ₂ k and the paper detection sensor 9a~9n detects time that detected the recording sheet rear end. The recording paper length difference detection unit 24 detects the time when each of the recording paper detection sensors 9a to 9n detects the leading edge of the recording paper, and the time interval T during which each of the recording paper detection sensors 9a to 9n detects the recording paper.
₁ k, T ₂ k and the recording paper detection sensors 9 a to 9 n based on the time when the recording paper detection sensors 9 a to 9 n have detected the rear end of the recording paper.
The difference ΔTkf in the time when n detected the leading edge of the recording paper, the difference ΔTkb in the time in which each of the recording paper detection sensors 9a to 9n detected the trailing edge of the recording paper, and the recording paper detection sensors 9a to 9
The time difference ΔTk required to pass through n is calculated.

The recording paper comparison unit 125 calculates the difference ΔTkf between the times when the recording paper detection sensors 9a to 9n detect the leading end of the recording paper calculated by the recording paper time difference calculation unit 124, and the recording paper detection sensors 9a to 9n. , The difference between the time ΔTkg at which the trailing edge of the recording paper was detected and the difference between the time required for the recording paper to pass through each of the recording paper detection sensors 9a to 9n were individually determined in advance and stored in the threshold storage unit 2. Compare with The error processing unit 127 includes a document comparison unit 123 and a recording paper comparison unit 125.
If any of the time differences exceeds a predetermined threshold value as a result of the comparison, a warning is output from the operation display unit 6 to the effect that the document or the recording paper was not conveyed correctly. Also,
If any of the time differences ΔTkf, ΔTkf, Tk of the comparison result of the recording paper comparison unit 125 exceeds a predetermined threshold value, the error processing unit 126 recalls the image data at that time from the image information storage unit 3 and performs a printing process. The recording paper transport unit 11 and the printing unit 5 are controlled so as to perform the following. Paper size detector 127
Detects a document size based on output signals from the paper size detection sensors 8a to 8n.

The document transport operation of the image processing apparatus having the above configuration will be described with reference to the flowchart of FIG. Here, two paper size detection sensors 8b and 8c will be focused on for the sake of simplicity.

When an operator sets a document on a document table (not shown) and inputs a copy processing instruction and a copy start instruction from the operation display unit 6, the main control unit 12 controls the document transport unit 10.
Is instructed to convey the document, and the conveyance of the document is started (step S1). When the document transport unit 10 receives the document transport instruction,
Documents set on the document table are conveyed one by one toward the document reading unit 4. When one of the paper size detection sensors 8b and 8c is turned on (step S2), the document time difference calculation unit 122 measures the difference in the leading edge detection time of the document and sends the turned on paper size detection sensors 8b and 8c. The measurement of the time required for the document to pass is started (step S
3).

Thereafter, when the document is further conveyed and the other paper size detection sensors 8b and 8c are turned on (step S4), the document time difference calculation unit 122 ends the measurement of the difference between the detection times of the leading edge of the document. Further, the measurement of the time required to pass through the paper size detection sensors 8b and 8c which have been turned on this time is started (step S5). Here, when both the paper size detection sensors 8b and 8c are turned on at the same time, the document time difference calculation unit 122 starts measuring the document leading edge detection time difference immediately after starting to measure the document leading edge detection time difference. It ends, and the time difference becomes zero. in this way,
By measuring the difference in the leading edge detection time of the document upstream of the document reading unit 4, it is possible to detect that the document has skewed before reaching the document reading unit 4.

Thereafter, when the original is further conveyed and one of the paper size detection sensors 8b and 8c is turned off (step S6), the original time difference calculation unit 122 passes through the turned off paper size detection sensors 8b and 8c. Then, the measurement of the time required for the end of the document is ended, and the measurement of the difference between the times at which the trailing edge of the document is detected is started (step S7).

Further, the other paper size detection sensor 8
When b and 8c are turned off (step S8), the document time difference calculation unit 122 outputs the other paper size detection sensors 8b and 8c.
The measurement of the time required to pass the document 8c and the measurement of the difference between the times when the trailing edge of the document is detected are terminated (step S).
9). When the time difference calculation unit 122 for the document finishes measuring the time required to pass the paper size detection sensors 8b and 8c, the measured paper size detection sensors 8b and 8c
Calculate the difference of the transit time with respect to. By measuring the difference between the times when the trailing edge of the document is detected, even if the document is skewed while passing through the paper size detection sensors 8b and 8c, it can be detected. Further, since the difference in the time required for the document to pass through the paper size detection sensors 8b and 8c is detected, the document is skewed while passing through the paper size detection sensors 8b and 8c and when the document is bent. This can be detected.

When the processing by the document time difference calculating section 122 is completed, the document comparing section 123 completes the document time difference calculating section 122.
The difference ΔTgf between the times when the paper size detection sensors 8b and 8c have detected the leading edge of the original is calculated by
The difference ΔTgb between the times when the originals b and 8c detect the trailing edge of the original and the difference ΔTg between the times required for the originals to pass through the respective paper size detection sensors 8b and 8c are compared with threshold values stored in the threshold storage unit 2 in advance. (Step S10). As described above, by comparing with the threshold value, it is possible to detect only a skew of a certain degree or more and a bending of the document that affect the reading of the document. Here, each threshold value stored in the threshold value storage unit 2 can be changed by the operator operating the operation display unit 6 according to the document conveyance speed in the paper size detection sensors 8a to 8n.

The error processing unit 126 includes a document comparison unit 123
If the time difference of any of the comparison results exceeds a predetermined threshold value, the operation display unit 6 outputs a warning that the document was not conveyed correctly. Thus, the operator can know that the reading of the document has not been performed normally.

Next, the recording paper transport operation will be described. Here, the skew detection process during recording paper conveyance is as follows.
This is almost the same as the skew feeding detection processing at the time of document conveyance described above.

When the operator inputs a print instruction for the image data stored in the image information storage unit 3 from the operation display unit 6, the main control unit 12 instructs the print unit 5 to print an image. When receiving an instruction to print an image, the printing unit 5 reads data of an image to be printed from the image information storage unit 3. The recording paper transport unit 11 transports recording paper of a predetermined size from the recording paper cassette 111 to the printing unit 5 one by one in accordance with the reading of the image data of the printing unit 5. When any of the recording paper detection sensors 9a to 9n is turned on, the recording paper time difference calculation unit 124 measures the time difference of the detection of the leading edge of the recording paper and outputs the turned on recording paper detection sensors 9a to 9n to the recording paper. The measurement of the time required to pass through is started.

Thereafter, when the recording paper is further conveyed and the other recording paper detection sensors 9a to 9n are turned on, the recording paper time difference calculating unit 124 ends the measurement of the difference in the detection time of the leading end of the recording paper. The measurement of the time required for the recording paper to pass through the recording paper detection sensors 9a to 9n that have been turned on this time is started. Thus, each of the recording paper detection sensors 9a to 9a
By measuring the difference in the time when the recording paper 9n detects the leading end of the recording paper, it is possible to detect that the recording paper has skewed before reaching the printing unit 5.

Thereafter, when the recording paper is further conveyed and one of the recording paper detection sensors 9a to 9n is turned off, the recording paper time difference calculating section 124 passes through the turned off recording paper detection sensors 9a to 9n. , And the measurement of the difference in the trailing edge detection time of the recording paper is started. Further, when the other recording paper detection sensors 9a to 9n are turned off, the recording paper time difference calculation unit 124 measures the time required to pass through the other recording paper detection sensors 9a to 9n and performs the measurement after the recording paper. The measurement of the difference between the end detection times ends. Further, the recording paper time difference calculation unit 124 calculates the difference between the measured times required to pass the recording paper detection sensors 9a to 9n. In this way, by measuring the difference between the detection times of the trailing edge of the recording paper, even if the recording paper is skewed while passing through the recording paper detection sensors 9a to 9n, it can be detected. Further, the recording paper is detected by each of the recording paper detection sensors 9a to 9a.
Since the difference in the time required to pass through the recording paper 9n is detected, it is possible to detect when the recording paper is skewed while passing through the recording paper detection sensors 9a to 9n and when the recording paper is bent. .

When the processing by the recording paper time difference calculating section 124 is completed, the recording paper comparing section 125 detects the difference between the leading edge detection time of the recording paper obtained by the recording paper time difference calculating section 124 and the trailing edge detection of the recording paper. The difference between the time and the difference between the recording paper passage times are compared with threshold values stored in the threshold storage unit 2 in advance. As described above, by comparing with the threshold value, it is possible to detect only the skew and the bending of the recording paper that have a certain degree or more that affect image printing.

The error processing unit 126 is a recording paper comparison unit 12
If any one of the time differences exceeds a predetermined threshold value as a result of the comparison, a warning indicating that the recording paper was not conveyed correctly is output from the operation display unit 6 and the image data at that time is displayed. The printing unit 5 and the recording paper carrying device 11 are controlled so as to be called again from the information storage unit 3 to perform the printing process. Thus, a normal image can be printed, and the operator can be notified that recording paper having a printing failure is mixed.

Here, in the above embodiment, the paper size detection sensors 8a to 8n are provided upstream of the original reading section 4, and the recording paper detection sensors 9a to 9n are provided facing the paper feed roller 113. 8a to 8n may be provided near the document discharge port, and the recording paper detection sensors 9a to 9n may be provided near the recording paper discharge port. Accordingly, it is possible to reliably detect a case where skewing occurs in any part of the transport path.

Next, as another embodiment, description will be given of a case where skew is detected by using a recording sheet position detection sensor which outputs a recording sheet position detection signal at at least two positions shifted in the recording sheet conveying direction. I do.

As shown in FIG. 7, the recording paper position detection sensor 1
3a and 13b are located apart from each other in the recording paper transport direction with the printing unit 5 interposed therebetween, for example. The main control unit 12a includes a clock generation unit 121, a document time difference calculation unit 12 as shown in FIG.
2. Document comparison unit 123, recording paper time difference calculation unit 124
a, a recording paper comparison unit 125a, an error processing unit 126, and a paper size detection unit 127. The recording paper time difference calculation unit 124a includes recording paper width detection units 25a to 25n and a recording paper length difference detection unit 26. Recording paper width detectors 25a-2
5n indicates that the recording paper is based on the signals from the recording paper position detection sensors 13a to 13n.
The time T ₁ k and the time T ₂ k passing through are measured. The recording paper length difference detecting unit 26 calculates the difference ΔTk between the two times T ₁ k and T ₂ k measured by the recording paper time difference calculating unit 124 a. The recording paper comparison unit 125a compares the time difference ΔTk calculated by the recording paper time difference calculation unit 124a with a predetermined threshold. The skew detection processing of the recording paper in this case will be described with reference to the flowchart of FIG.

When the operator inputs a print instruction for the image data stored in the image information storage unit 3 from the operation display unit 6, the printing unit 5 converts the image data of the image to be printed from the image information storage unit 3 as described above. In response to the reading of the image data by the printing unit 5, the recording paper transport unit 11 prints out recording paper of a predetermined size one by one from the recording paper cassette 111.
(Step S21). When the recording paper reaches the upstream recording paper position detection sensor 13a and the upstream recording paper position detection sensor 13a is turned on (step S2).
2), the recording paper time difference calculation unit 124a starts measuring a time T ₁ k required for the recording paper to pass through the upstream recording paper position detection sensor 13a (step S23). When the recording paper further advances and the upstream recording paper position detection sensor 13a is turned off (step S24), the recording paper time difference calculation unit 124a causes the recording paper position detection sensor 1a to detect that the recording paper is upstream.
The measurement of the time T ₁ k required to pass through 3a ends (step S25).

When the recording paper further advances and reaches the recording paper position detection sensor 13b on the downstream side, and the recording paper position detection sensor 13b on the downstream side is turned on (step S26), the recording paper time difference calculation unit 124a similarly performs recording. Measurement of the time T ₂ k required for the paper to pass through the downstream recording paper position detection sensor 13b is started (step S27), and when the downstream recording paper position detection sensor 13b is turned off (step S28),
The recording paper time difference calculation unit 124a calculates the time T ₂ k required for the recording paper to pass through the downstream recording paper position detection sensor 13b.
Measurement is completed (step S29). The recording paper time difference calculation unit 124a calculates the time T ₁ k required for the recording paper to pass the upstream recording paper position detection sensor 13a and the time required for the recording paper to pass the downstream recording paper position detection sensor 13b. The difference ΔTk from the calculated time T ₂ k is calculated (step S30).
The recording paper comparison unit 125a calculates the difference Δ between the threshold value stored in the threshold value storage unit 2 and the time measured by the recording paper time difference calculation unit 124a.
Compare with Tk. The error processing unit 126 compares the time required for the recording paper to pass through the upstream recording paper position detection sensor 13a and the time required for the recording paper to pass through the downstream recording paper position detection sensor 13b. If the difference ΔTk from the time required to pass through exceeds the threshold value (step S31), a warning that skewing or the like has occurred is displayed on the operation display unit 6 (step S32), and the printing unit 5 and the recording paper transport unit 11 are controlled to perform reprinting processing (step S33). In this way, for example, by detecting the time when the recording paper passes upstream and downstream of the printing unit 5,
If the difference exceeds the threshold value, it is determined that skew has occurred, so that it can be detected that skew or paper folding has occurred near the printing unit 5. Further, the recording paper position detection sensor 13a
.About.13n are provided at the recording sheet supply start position and at the recording sheet discharge port, and the occurrence of skew or the like therebetween can be detected.

Further, with this configuration, there is no need to provide a sensor dedicated to skew detection, and the configuration can be simplified.

Further, when the recording paper position detecting sensors 13a and 13b are provided apart from each other in the recording paper conveying direction with the printing unit 5 interposed therebetween, the recording paper width detecting units 25a to 25n of the recording paper time difference calculating unit 124a calculate the respective calculated values. Recording paper position detection sensor 1
The time T ₁ k required for the recording paper to pass through 3a, 13b,
T ₂ k is calculated, and the recording paper comparison unit 125a calculates each recording paper position detection sensor 1 calculated by the recording paper time difference calculation unit 124a.
The time T ₁ k required for the recording paper to pass through 3a, 13b,
T ₂ k may be compared with predetermined thresholds so that skew can be detected at two places where the transport speed is different. The recording paper transport operation of the image processing apparatus in this case will be described with reference to the flowchart in FIG.

When the operator inputs a print instruction for the image data stored in the image information storage unit 3 from the operation display unit 6, the recording paper comparison unit 125a stores the image data in the threshold storage unit 2 based on the size of the recording paper on which the image is to be printed. The selected threshold is selected (step S41). Further, the printing unit 5 reads out image data of an image to be printed from the image information storage unit 3, and the recording paper transport unit 11 transfers recording paper of a predetermined size from the recording paper cassette 111 in accordance with the reading of the image data of the printing unit 5. The sheets are conveyed one by one toward the printing unit 5 (step S42). Thereafter, when the upstream recording paper position detection sensor 13a is turned on (step S43), the recording paper time difference calculation unit 124a determines the time T ₁ k required for the recording paper to pass through the upstream recording paper position detection sensor 13a. Measurement is started (step S44). When the recording paper further advances and the upstream recording paper position sensor 13a is turned off (step S45), the recording paper time difference calculation unit 124a causes the recording paper position detection sensor 1a to detect that the recording paper is upstream.
The measurement of the time T ₁ k required to pass through 3a ends (step S46). The recording paper comparison unit 125a compares the selected threshold value with the time T ₁ k measured by the recording paper time difference calculation unit 124a. The error processing unit 126 determines that the time T ₁ k required for the recording paper to pass through the upstream recording paper position detection sensor 13a exceeds the threshold as a result of the comparison by the recording paper comparison unit 125a (step S47), a warning that skewing or the like has occurred is displayed from the operation display unit 6 (step S53), and the printing unit 5 and the recording paper transport unit 11 are instructed to perform reprinting processing (step S5).
4).

When the recording paper further advances and reaches the downstream recording paper position detection sensor 13b, and the downstream recording paper position detection sensor 13b is turned on (step S48), the recording paper time difference calculation unit 124a determines that the recording paper has been detected. The measurement of the time T ₂ k required to pass through the downstream recording paper position detection sensor 13b is started (step S49), and when the downstream recording paper position detection sensor 13b is turned off (step S50), the recording paper is detected. The time difference calculation unit 124a ends the measurement of the time T ₂ k required for the recording paper to pass through the downstream recording paper position detection sensor 13b (step S51). Recording paper comparison section 125
“a” compares the selected threshold value with the time T ₂ k measured by the recording paper time difference calculation unit 124a. The error processing unit 126
As a result of the comparison by the recording paper comparison unit 125a, when the time T ₂ k required for the recording paper to pass through the downstream recording paper position detection sensor 13b exceeds the threshold (step S5).
2) At the same time, a warning indicating that skew has occurred is displayed on the operation display section 6 (step S53), and the printing section 5 and the recording paper transport section 11 are controlled to perform reprinting processing (step S54). As described above, since the image processing apparatus detects that the skew or the paper has broken before and after the printing unit 5, it can more accurately detect whether the skew or the like affecting the printing has occurred.

In the case where the recording paper position detecting sensors 13a and 13b are provided apart from each other in the recording paper conveying direction with the printing section 5 interposed therebetween, the recording paper position detecting sensor 13b on the downstream side is particularly provided.
Is located near the printing unit 5, the recording paper time difference calculation unit 124a measures the time difference ΔTkf for detecting the leading edge of the recording paper and the time difference ΔTkb for detecting the trailing edge of each of the recording paper position detection sensors 13a and 13b. , The measured time difference ΔTkf,
The difference is calculated based on ΔTkb, and the difference is calculated by the recording paper comparing unit 125a.
Is the detection time difference ΔTkf of the leading end of the recording paper calculated by the recording paper time difference calculation unit 124a and the detection time difference ΔT of the trailing end of the recording paper.
The difference from kb may be compared with a predetermined threshold value in the threshold value storage unit 2. Thus, when the leading end of the recording paper is applied to the recording paper position detection sensor 13b and skew occurs during printing by the printing unit 5, it can be detected.

Further, in the case where the recording paper position detecting sensors 13a and 13b are provided apart from each other in the recording paper conveying direction with the printing section 5 interposed therebetween, the recording paper position detecting sensors 13a and 13b are particularly provided.
If b is at a close position, the recording paper time difference calculation unit 124
The recording paper length detector 26a of FIG.
n, based on the detection time of the leading edge of the recording paper and the detection time of the trailing edge of the recording paper, the time ΔT ₁₂ during which both recording paper position detection sensors 13a and 13b detect the recording paper is measured. The comparing unit 125a may compare the time measured by the recording paper time difference calculating unit 124a with a predetermined threshold. Since the length of the recording paper in the conveyance direction and the conveyance speed of the recording paper are known in advance, both recording paper position detection sensors 13
The time during which both a and 13b detect the recording paper can be known in advance. When skew or paper breakage occurs, a difference occurs between this time and the time ΔT ₁₂ measured by the recording paper time difference calculation unit 124a, so that skew or the like can be detected.
The recording paper transport operation in this case will be described with reference to the flowchart of FIG.

When the operator inputs a print instruction for the image data stored in the image information storage unit 3 from the operation display unit 6, as described above, the recording paper comparison unit 125a sets the threshold based on the recording paper size for printing the image. The threshold value stored in the storage unit 2 is selected (step S61), and the printing unit 5 sets the image information storage unit 3
The recording paper transport unit 11 transports the recording paper of a predetermined size from the recording paper cassette 111 one by one to the printing unit 5 one by one according to the reading of the image data of the printing unit 5. (Step S62). The recording paper transported by the recording paper transport unit 11 is a recording paper position detection sensor 1.
3a and 13b, the recording paper position detection sensors 13
a, the 13b is turned on (step S63), the time difference calculating section 124a for recording paper starts measuring of the recording paper passing time [Delta] T ₁₂ (step S64), the recording sheet position detection sensor 1
The measurement is continued until one of 3a and 13b is turned off (step S65). The error processing unit 126 compares the selected threshold value with the passing time ΔT ₁₂ measured by the recording paper time difference calculation unit 124a (step S66). If the transit time ΔT ₁₂ measured by the recording paper time difference calculation unit 124a exceeds the threshold, the error processing unit 126 displays a warning that skewing or the like has occurred from the operation display unit 6 (step S67). ), The printing section 5 and the recording paper transport section 11 are controlled to perform reprinting processing (step S68). As described above, the skew and the skew of the recording paper are detected based on the time when both the recording paper position detection sensors 13a and 13b are on, so that the conveyance of the recording paper may be delayed halfway. Can detect that fact.

Note that each threshold stored in the threshold storage unit 2 is
For example, if the threshold value can be changed by input from the operation display unit 6, the threshold value can be changed according to the state of each image processing apparatus and its use status, and versatility is increased.

[0055]

As described above, according to the present invention, each paper size detection sensor adjusts the leading edge of a document based on signals from the paper size detection sensors arranged in the range of the minimum document width on a line orthogonal to the document conveyance direction. The difference between the detected times, the difference between the times when each paper size detection sensor detects the trailing edge of the document, and the difference between the times required for the document to pass through each paper size detection sensor are calculated, and the difference between the calculated times is calculated. Each of them is compared with a predetermined threshold value, and if any of the time differences exceeds the predetermined threshold value, a warning is output that the document was not correctly conveyed. A warning can be output.

Further, since skew is detected using the paper size detection sensor, it is not necessary to newly provide a sensor, and the apparatus configuration can be simplified.

Also, based on the signals from the recording paper detection sensors arranged in the range of the minimum recording paper width on a line perpendicular to the document conveyance direction, the difference between the time when each recording paper detection sensor detects the leading end of the recording paper, The difference between the time when the recording paper detection sensor detects the trailing edge of the recording paper and the difference between the time required for the recording paper to pass through each recording paper detection sensor is calculated, and the calculated time difference is determined in advance. If any of the time differences exceeds a predetermined threshold value, a warning indicating that the recording paper has not been properly conveyed is output, and the image data at that time is recalled to perform the printing process. , The skew of the recording paper can be reliably detected, the image with the printing failure can be printed again, and the operator can be notified to remove the recording paper with the printing failure.

The difference between the time required for the recording paper to pass through each recording paper position detection sensor is calculated based on the signal from the recording paper position detection sensor which is shifted in the recording paper conveyance direction. Since the time difference is compared with a predetermined threshold value, it is possible to detect, for example, skew of the recording paper before and after the printing position, and detect skew occurring near the printing position. Further, if a recording sheet position detection sensor is provided at the recording sheet conveyance start position and the recording sheet discharge port, it is possible to detect the occurrence of skew or the like therebetween.

Further, since the sensor for detecting the position of the recording paper is used as the recording paper position detection sensor, it is not necessary to newly provide a sensor, and the configuration of the apparatus can be simplified.

Further, the time required for the recording paper to pass through each recording paper position detection sensor is calculated based on the signal from the recording paper position detection sensor which is shifted in the recording paper conveyance direction, and
Since the calculated time required to pass each recording paper position detection sensor is compared with a predetermined threshold value, skew can be detected at two places where the conveying speed is different, and skew can be detected more accurately. can do.

Further, based on a signal from a recording paper position detecting sensor which is shifted in the recording paper conveying direction, a difference in time when each recording paper position detecting sensor detects the leading end of the recording paper and a trailing end are detected. A time difference is measured, the difference is calculated based on the measured time difference, and the difference between the calculated detection time difference of the leading edge of the recording paper and the detected time difference of the trailing edge of the recording paper is compared with a predetermined threshold. Therefore, for example, skew occurring during printing can be detected when the downstream recording paper position detection sensor is provided near the printing position.

Further, based on a signal from a recording paper position detecting sensor which is shifted by a predetermined distance in the recording paper conveying direction, the time during which each recording paper position detecting sensor detects the recording paper together is measured and measured. Since the calculated time is compared with a predetermined threshold value, it is possible to detect a skew of the recording paper, including a change in the transport speed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a layout diagram of a paper size detection sensor.

FIG. 3 is a layout diagram of a recording paper detection sensor.

FIG. 4 is a configuration diagram of a main control unit.

FIG. 5 is a waveform diagram of outputs of a paper size detection sensor and a recording paper detection sensor.

FIG. 6 is a flowchart illustrating a document conveying operation.

FIG. 7 is a layout diagram of a recording paper position detection sensor shifted in a recording paper conveyance direction.

FIG. 8 is a configuration diagram of a main control unit that detects skew using a recording sheet position detection sensor.

FIG. 9 is a flowchart in a case where skew is detected based on a difference in a recording paper passing time between sensors.

FIG. 10 is a flowchart illustrating a case where skew is detected based on the passage time of a recording sheet through a sensor.

FIG. 11 is a flowchart illustrating skew detection from a time when a recording sheet position detection sensor is on.

[Explanation of symbols]

 2 Threshold storage unit 3 Image information storage unit 4 Document reading unit 5 Printing unit 8a to 8n Paper size detection sensor 9a to 9n Recording paper detection sensor 121 Clock generation unit 122 Document time difference calculation unit 123 Document comparison unit 124 Recording paper time difference Calculation section 125 Recording paper comparison section 126 Error processing section 127 Paper size detection section 13 Recording paper position detection sensor 21 Document width detection section 22 Document length difference detection section 23 Recording paper width detection section 24 Recording paper length detection section 25 Recording paper width detection Unit 26 Recording paper length difference detection unit

Claims (6)

[Claims] 1. An image forming apparatus comprising: at least two paper size detection sensors arranged in a range of a minimum document width on a line orthogonal to a document conveyance direction; Detects the document size based on the detection signal,
An image processing apparatus that reads an image on a document based on the detected document size has a time difference calculating unit, a comparing unit, and an error processing unit, and the time difference calculating unit detects each paper size based on a signal from each paper size detecting sensor. Calculate the difference between the time when the front edge of the document is detected, the time when each paper size detection sensor detects the rear edge of the document, and the difference between the time required for the document to pass through each paper size detection sensor. The difference between the time when each paper size detection sensor detects the leading edge of the document calculated by the time difference calculation unit, the difference between the time when each paper size detection sensor detects the trailing edge of the document, and the document passes through each paper size detection sensor The error processing unit compares the difference in the time required to perform the processing with the threshold individually determined in advance, and as a result of the comparison by the comparing unit, if any one of the time differences exceeds the predetermined threshold, the document is conveyed. Image processing apparatus and outputs a warning that has not been done properly. 2. An image processing apparatus which conveys recording paper one by one and prints images stored in an image information storage section on the recording paper, wherein the images are arranged in a range of a minimum recording paper width on a line orthogonal to a recording paper conveying direction. It has at least two recording paper detection sensors, a time difference calculation unit, a comparison unit, and an error processing unit. The time difference calculation unit is configured such that each recording paper detection sensor detects the leading end of the recording paper based on a signal from each recording paper detection sensor. The difference between the detected times, the difference between the times when each recording paper detection sensor detects the trailing edge of the recording paper, and the difference between the times required for the recording paper to pass through each recording paper detection sensor are calculated. The difference between the time when each recording paper detection sensor detects the leading end of the recording paper calculated by the time difference calculation unit, the difference between the time when each recording paper detection sensor detects the rear end of the recording paper, and the case where the recording paper detects each recording paper The difference in the time required to pass the sensor The error processing unit outputs a warning indicating that the conveyance of the recording paper has not been correctly performed if any of the time differences exceeds a predetermined threshold value as a result of the comparison by the comparison unit. And an image processing device for recalling the image data at that time from the image information storage unit and performing printing processing. 3. A recording paper position detection sensor for outputting a recording paper position detection signal on a recording paper conveyance path is provided at at least two positions shifted in the recording paper conveyance direction, and the recording paper is conveyed one by one. In an image processing apparatus that detects a recording paper position based on an output of a paper position detection sensor and prints an image stored in an image information storage unit on the recording paper based on the detected recording paper position, a time difference calculating unit includes a recording paper Based on the signal from the position detection sensor, the difference between the time required for the recording paper to pass through each recording sheet position detection sensor is calculated, and the comparison unit calculates the time difference calculated by the time difference calculation unit as a predetermined threshold. The error processing unit compares the time required to pass each recording sheet position detection sensor as a result of the comparison by the comparison unit. Is output, and the An image processing apparatus for retrieving image data from an image information storage unit and performing printing processing. 4. The time difference calculating section calculates the time required for a recording sheet to pass through each recording sheet position detection sensor based on a signal from each recording sheet position detection sensor. 4. The image processing apparatus according to claim 3, wherein the calculated time required to pass through each recording sheet position detection sensor is compared with a predetermined threshold value. 5. The time difference calculating section calculates a difference between a time when each of the recording paper position detection sensors detects the leading edge of the recording paper and a difference between a time when the trailing edge of the recording paper is detected, and calculates a difference between the calculated two times. 4. The image processing according to claim 3, wherein the difference is calculated, and the comparing unit compares the difference between the detected time difference of the leading end of the recording paper and the detected time difference of the trailing end of the recording paper calculated by the time difference calculating unit with a predetermined threshold value. apparatus. 6. A recording paper position detection sensor is provided at two places shifted by a predetermined distance in the recording paper conveyance direction, and a time difference calculation unit calculates a time during which each of the recording paper position detection sensors detects the recording paper. The image processing apparatus according to claim 3, wherein the comparing unit compares the time calculated by the time calculating unit with a predetermined threshold.