JP2002211793A - Correction and setting methods for carrying error detection means in image forming device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide methods for correcting and setting the carrying error detecting conditions of an image forming device capable of easily and accurately correcting an error amount, and the image forming device. SOLUTION: On a carried sheet, reference sensors 52A and 52B are installed at specified intervals along the lateral direction of a carrying route 12. In this state, the image forming device carries the sheet to form the same reference images 54A and 54B at the same timing. Since these reference images 54A and 54B are formed at the same position in a carrying direction even if the sheet A moves aslant, the amount of displacement due to a slanting movement can be accurately detected by detecting, with the reference sensors 52A and 52B, the times T2A and T2B required to pass through the distances between the top ends of the sheets and the rear end of the reference images 54A and 54B and determining a time difference ΔT2 thereof. Thus, based on the time difference ΔT2, the slanting detection conditions can be corrected accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for correcting an abnormality detection condition for detecting skew of a sheet by a conveyance abnormality detection means in an image forming apparatus, and a method for setting an abnormality detection condition for detecting a registration error. And an image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus and the like have been provided with a conveyance abnormality detecting device for detecting skew of a sheet, registration deviation, and the like in order to accurately form an image on a sheet.

A transport abnormality detecting device for detecting skew is provided in a direction orthogonal to a transport direction on a transport path (hereinafter, referred to as a width direction).
A plurality of edge detection sensors for detecting the edge of the paper,
A transport abnormality such as skew of a sheet is detected based on a shift amount (time difference) between detection timings of a plurality of edge detection sensors (hereinafter referred to as Conventional Example 1).

The following configuration is disclosed as another conventional example of the transport abnormality detecting device.

For example, in Japanese Patent Application No. 9-346803 (hereinafter referred to as Conventional Example 2), a plurality of actuators that rotate around an axis when pressed by an end of a recording sheet are provided in a width direction. Further, a configuration is disclosed in which the passage timing of the leading edge and the trailing edge of the recording paper is detected based on the rotation timing of the actuator. Therefore, the passage time of the recording sheet in each of the plurality of actuators can be obtained, and an abnormality at the leading end or the trailing end of the recording sheet can be detected by comparing the passage time with the normal passage time.

In Japanese Patent Application No. 10-4738 (hereinafter referred to as Conventional Example 3), two sensors which are offset along the sheet conveying direction and the width direction are arranged. The elapsed time from when the leading edge of the sheet is detected to when the other sensor detects the leading edge of the sheet is measured by one counter. If the count value is equal to the time for transporting the paper by the sensor interval, a configuration is disclosed in which the paper is determined not to be skewed.

Further, a conveyance error detecting device for detecting a registration error is provided at a predetermined position on a conveyance path, and compares the elapsed time from the output timing of a reference signal until the sheet passes through the sensor with a set time. To detect a registration shift.

[0008]

However, as in the prior arts 1 and 2, when a plurality of detection sensors are provided in the width direction to detect a transport abnormality based on the amount of deviation of the detection timing, the detection is not performed. The amount of deviation of the detection timing becomes inaccurate due to a sensor mounting error or sensitivity difference, and there is a possibility that a transport abnormality is erroneously detected.

Further, even in the case where the detection sensor is offset in the transport direction as in Conventional Example 3, the transport abnormality is detected by comparing the transport time based on the sensor interval. There is a risk of erroneous detection due to a mounting error or the like.

[0010] Further, even in the conveyance error detecting device for detecting a registration deviation, there is a possibility that an erroneous detection is similarly caused due to a mounting error or a difference in sensor sensitivity.

Therefore, as a countermeasure against such erroneous detection, the operator performs test printing before using the conveyance abnormality detecting device, measures the detection timing of a plurality of sensors, and determines the skew amount of the actually discharged paper. Is visually measured to correct the detection timing. However, even if the correction is once performed, it is necessary to perform test printing again for confirmation, and if there is an error, the test printing must be performed again and setting must be performed, which is complicated.

Accordingly, in order to solve the above-mentioned inconveniences, an object of the present invention is to provide a correction method and a setting method of an abnormality detecting means of an image forming apparatus for simply and accurately correcting an error, and an image forming apparatus. I do.

[0013]

According to the first aspect of the present invention,
In the image forming apparatus, the shift amount of the edge detection timing of the sheet detected by a plurality of edge detection units arranged in a straight line at predetermined intervals in the width direction orthogonal to the sheet conveyance direction on the conveyance path is determined. A method of correcting conveyance error detecting means for detecting an abnormality in sheet conveyance based on a first step of detecting end portions of a sheet conveyed on a conveyance path by a plurality of end detection means; A second step of forming a plurality of the same reference images at the same timing by image forming means at a position on the sheet corresponding to a position where the end detecting means is provided in the width direction of the road; A plurality of measuring means are attached to a position corresponding to a position where the edge detecting means is disposed in the width direction on the transport path on the downstream side of the means, and the reference image is provided from an edge of the sheet. A third step in which each measuring means measures a passing time in which the time passes, and a deviation amount of the detection timing by the plurality of end detecting means and a deviation amount of the passing time by the plurality of measuring means are determined. And a fourth step of changing an abnormality detection condition of the transport abnormality detecting means so as to detect a transport error of the sheet based on a value obtained by adding or subtracting the difference between the two offset amounts to the deviation amount of the sheet.

The operation of the first aspect of the present invention will be described.

A plurality of edge detecting means respectively detect the edge of the sheet conveyed on the conveying path. Further, the same reference image is formed at the same timing by the image forming unit at a position on the sheet corresponding to the position of the edge detection unit in the width direction, and the sheet passes through the measuring unit. Thus, the transit time from the edge of the sheet to the reference image is measured.

Here, when the sheet is skewed, the end of the sheet reaches each measuring means at different timings, but the reference image arrives at the same timing. Therefore, the shift amount (time difference) due to skew is accurately detected based on the shift amount (time difference) of the passing time by the measuring means.
On the other hand, the deviation amount (time difference) due to the detection timing by the edge detection means includes the deviation amount of the detection timing due to the mounting error of the edge detection means and the sensitivity difference in addition to the deviation amount of the detection timing due to the skew of the sheet. ing.

Therefore, the correction means obtains the difference between the detection timing shift amount and the transit time shift amount to obtain the shift amount due to the mounting error or the sensitivity difference (the difference between the two shift amounts). The abnormality detection condition of the conveyance error detection means is changed so as to detect a sheet conveyance error based on a value obtained by adding or subtracting the difference between the two shift amounts. Therefore, the setting can be changed so that the abnormality detecting means of the sheet conveying device performs the abnormality detection based on the shift amount based only on the conveyance abnormality due to the skew.

That is, it is possible to simply and accurately correct the abnormality detection condition of the transport abnormality detecting means.

According to a second aspect of the present invention, in the image forming apparatus, the registration error is determined based on the elapsed time from the reference timing to the edge detection timing of the sheet detected by the edge detection means disposed on the conveyance path. A first step of detecting an elapsed time from the reference timing to detecting an end of a sheet conveyed on the conveyance path by the end detection unit; and A second step in which an image forming unit forms a reference image at a predetermined timing at a position on the sheet corresponding to a position where the end detection unit is provided in the width direction of the transport path; A measuring unit is attached to a position corresponding to a position where the edge detecting unit is disposed in the width direction on the transport path on the downstream side of the unit. A third step in which the measuring means measures a transit time when the reference image passes, and a difference between the transit time and the theoretical transit time is determined, and a registration deviation is calculated based on a time obtained by adding or subtracting the difference to the elapsed time. A fourth step of setting an abnormality detection condition of the transport abnormality detecting means so as to detect the abnormality.

The operation of the invention will be described.

The edge detecting means detects the edge of the sheet conveyed on the conveying path. Further, the sheet to be conveyed has a reference image formed at a predetermined timing by the image forming unit at a position on the sheet corresponding to the position of the edge detecting unit in the width direction, and the sheet passes through the measuring unit. The transit time from the edge of the paper to the reference image is measured.

An abnormality detection condition is set so as to detect a registration deviation based on a value obtained by adding or subtracting a difference between the transit time and a theoretical transit time calculated from the paper transport speed. In other words, the difference corresponds to a registration deviation, and a transit time (reference transit time) without a registration deviation can be set by adjusting the difference with respect to the transit time. That is, it is possible to accurately set the abnormality detection condition of the conveyance abnormality detection unit that detects the registration deviation.

According to a third aspect of the present invention, the correction method of the first aspect corrects a conveyance abnormality detection condition of the conveyance abnormality detection means.

The operation of the third aspect of the present invention will be described.

Since the skew detection condition is accurately corrected by the correction method according to the first aspect, the skew detection of the sheet is not affected by the sensitivity of the edge detection means and the mounting error. Can be accurately detected.

According to a fourth aspect of the present invention, a transfer abnormality detecting condition of the transfer abnormality detecting means is set by the setting method of the second aspect.

The operation of the invention will be described.

Since the registration error abnormality detection condition is set with high accuracy by the setting method according to the second aspect, the conveyance error detection means can be accurately registered without being affected by the sensitivity or mounting error of the edge detection means. It is possible to detect the ration deviation.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) An image forming apparatus including a sheet conveying device according to a first embodiment of the present invention will be described. (Schematic Description of Image Forming Apparatus) FIG.
As shown in FIG. 1, along a transport path 12, a paper supply unit 14 for supplying paper, a transport abnormality detection unit 16 described below, an image forming unit 18 for forming a predetermined image on the paper, A fixing unit 20 for fixing on paper, and a reference sensor attachment unit 2 to which reference sensors 52A and 52B described later are attached.
2 and a discharge tray 24 from which an image-formed sheet is discharged
And a purge tray 26 from which a sheet having a defective image formation is discharged.

In the image forming section 18, a charger 30, an optical scanning device 32, a developing unit 34, a transfer unit 36, and a cleaning unit 38 for removing toner are disposed around the photoreceptor belt 28.
Therefore, an electrostatic latent image is formed on the photosensitive belt 28 charged by the charger 30 by the laser beam from the optical scanning device 32, and a toner image is formed on the portion by the developing device 34. The toner image formed on the photoreceptor belt 28 is transferred from the photoreceptor belt 28 onto the sheet by the transfer device 36, and the toner remaining on the photoreceptor belt 28 is removed by the cleaning unit 38.

As shown in FIG. 5A, the conveyance abnormality detecting section 16 is arranged on a straight line at a predetermined interval in a direction perpendicular to the sheet conveyance direction of the conveyance path 12 (hereinafter, referred to as a width direction). And a pair of end detection sensors 50A and 50B. Each of the end detection sensors 50A and 50B is configured by a transmission type photoelectric switch including a light emitting element and a light receiving element. Therefore, the sheet is detected by the edge detection sensor 5.
0A, 50B each time the end detection sensor 5
The leading and trailing edges of the paper can be detected based on the output signals 0A and 50B (see FIG. 5B).

As shown in FIG. 6A, a pair of reference sensors 52A and 52B are mounted on the correction reference portion 22 in a straight line at a predetermined interval in the width direction of the transport path 12. . As shown in FIG. 3, the mounting position is the same as the position where the end detection sensors 50A and 50B are arranged in the width direction of the transport path 12.

The reference sensors 52A and 52B are reflection sensors for detecting the amount of reflected light applied to the image forming surface of the sheet. Therefore, based on the output signal (see FIG. 6B), the leading and trailing edges of the sheet are detected, and the leading and trailing edges of black reference images 54A and 54B formed on an image forming surface described later are detected. Can be. The reference sensors 52A and 52B are mounted only at the time of correction, which will be described later, and are accurately positioned and fixed.

Further, as shown in FIG. 4, the image forming apparatus 10 includes a control unit 40, and the above-described end detection sensors 50A and 50B and the reference detection sensors 52A and 52B.
In addition to the input of the output signal, an image is formed by the input from the operation unit 42, the test printing is started, and the processing state of the image forming apparatus 10 is displayed on the display 44.

In the control section 40, an end detection sensor 50A,
The time difference (shift amount) ΔT1 of the edge detection timing of the sheet is calculated based on the output signal from 50B (see FIG. 5B), and the conveyance abnormality is detected based on the time difference ΔT1. . Specifically, when the time difference ΔT1 is not within the predetermined range, it is determined that the skew of the sheet is in the allowable range or more (abnormal conveyance), and the image is formed on the purge tray 26 without forming an image on the sheet. It is set so that the sheet is discharged and an error message is displayed on the display 44.

The control unit 40 outputs the output signals of the reference sensors 52A and 52B (see FIG. 6B) when correcting the above-described transport abnormality detection condition by a correction method described later.
Is also input to the control unit 40. Reference sensors 52A, 52
In the case of B, not only the leading edge and the trailing edge of the sheet, but also the black reference images 54A and 54B formed on the sheet can be detected. That is, as shown in FIG. 6B, the detection signals of the reference sensors 52A and 52B fall at the leading edge of the sheet, rise at the leading edge of the image, and fall at the trailing edge of the image. From the change in this signal, the transit time T2A, T2B from the leading edge of the sheet to the trailing edge of the image is obtained for each of the reference sensors 52A, 52B, and the time difference ΔT2 between the reference sensors 52A, 52B = T2A−
T2B is obtained (see FIG. 8B).

Further, the control unit 40 controls the time difference Δ
The correction of the transport abnormality detection condition is performed based on T1 and the time difference ΔT2.

A description will now be given, with reference to the flowchart shown in FIG. 1, of the detection of a conveyance error in the image forming apparatus 10 configured as described above.

First, a test signal is input to the control unit 40 by an operator's input from the operation unit 42 (step 100). Based on this test signal, a drive signal is transmitted from the control unit 40 to the transport system of the apparatus, and the paper A is transported from the paper supply unit 14 to the image forming unit 18 (step 102). At the same time, a reference image creation signal (image data of the reference image) is output to the optical scanning device 32 (step 104).

When the sheet A passes through the conveyance abnormality detection section 16 in the conveyance path 12, the edge detection sensor 50
Based on the detection signals of A and 50B, the control unit 40 calculates a time difference ΔT1 of the trailing edge detection timing of the sheet A between the edge detection sensors 50A and 50B (step 106).

The time difference ΔT1 is for detecting the time difference of the detection timing due to the skew of the sheet A, but also includes the time difference due to the sensitivity difference between the end detection sensors 50A and 50B and the mounting error. For example, as shown in FIG. 7A, when the edge detection sensors 50A and 50B are slightly offset in the transport direction due to a mounting error, a time difference due to the offset is included. That is, as shown by the two-dot chain line in FIG. 7A, the time difference ΔT5 is detected even if the sheet A does not skew (see FIG. 7B).

Subsequently, an image is formed by the sheet A reaching the transfer section 20. Here, based on the image data of the test image described above, rectangular black reference images 54A, 54A, 54A, 5A at the same timing at positions corresponding to the positions of the reference sensors 52A, 52B in the paper width direction.
4B is formed.

When the sheet A on which the reference images 54A and 54B are formed reaches the correction reference section 22,
In the control unit 40, as shown in FIG. 8B, based on the output signals from the reference sensors 52A and 52B, the transit time T2 from the leading edge of the sheet to the trailing edge of the reference image, respectively.
A and T2B are obtained, and a time difference ΔT2 = T2A−T is obtained therefrom.
2B is calculated (step 108).

The passing times T2A and T2B do not depend on mounting errors of the reference sensors 52A and 52B.
That is, as shown in FIG. 8A, when the reference images 54A and 54B are formed on the sheet A by the image forming unit 18, the reference image 54
A and 54B are formed at the same timing. That is,
As shown in FIG. 8A, when the sheet A is skewed, the distance from the leading edge of the sheet to the trailing edge of the reference image varies along the transport direction. Moreover, the transit time T2
Since A and T2B detect the transit time from the leading edge of the sheet A to the trailing edges of the reference images 54A and 54B on the respective reference sensors 52A and 52B, they do not depend on the mounting error (FIG. B) (52B)). For example, even if the reference sensor 52B is offset in the transport direction (see the broken line in FIG. 8A), the passage time T2 does not change. In addition, the sensitivities of the reference sensors 52A and 52B that match each other are selected. Therefore, it can be said that the time difference ΔT2 is a time difference based only on the skew amount of the sheet A.

Subsequently, the control unit 40 determines whether or not the time difference ΔT1 is equal to the time difference ΔT2 (step 11).
0). As described above, the time difference ΔT1 may include the time difference due to the skew of the sheet A and the time difference due to the sensor mounting error and the sensor sensitivity difference. ,
It is determined whether there is a mounting error or the like between the end detection sensors 50A and 50B.

Therefore, the time difference ΔT1 and the time difference ΔT2
Are equal, it is determined that there is no mounting error (offset in the transport direction) or a sensitivity difference between the end detection sensors 50A and 50B, a message indicating that the correction processing has been completed is displayed on the display 44, and the correction processing is completed (step). 114).

On the other hand, if the time difference ΔT1 and the time difference ΔT2 are not equal, it is determined that there is a mounting error (offset in the transport direction) or a sensitivity difference between the end detection sensors 50A and 50B, and the abnormality detection condition is corrected. (Step 112). Specifically, (ΔT1−ΔT2) is set as a correction value, and when the above-described time difference ΔT1 of the skew detection sensor is detected in the abnormality detection control, (ΔT1−ΔT2) is set to ΔT1.
T2) is changed so that abnormality detection is performed based on the value obtained by adding (adding / subtracting | ΔT1−ΔT2 |).
Subsequently, a message indicating that the correction process has been completed is displayed on the display 44, and the correction process ends (step 114). After the correction is completed, the reference sensors 52A and 52B are removed from the reference sensor mounting section 22 of the image forming apparatus 10.

As described above, in this embodiment, the reference sensors 52A and 52B are attached to the transport path 12 of the image forming apparatus 10 with high accuracy, and the reference images 54A and 54B are formed on the paper. By simply transporting one sheet, the abnormality detection condition can be accurately corrected.

In particular, since the reference sensors 52A and 52B are mounted on the image forming apparatus 10 as jigs, the effects of differences in sensor sensitivity and mounting errors can be eliminated, and accurate correction can be performed. (Second Embodiment) Next, a method of setting registration deviation detection in an image forming apparatus according to a second embodiment of the present invention will be described. Components similar to those of the first embodiment include:
The same components are denoted by the same reference numerals, and detailed description thereof is omitted.

That is, only the end detection sensor 50B is provided in the conveyance abnormality detection section 16 of the image forming apparatus 10 (see FIG. 9A), and only the reference sensor 52B is provided in the reference sensor mounting section 22. (See FIG. 10A).

The control unit 40 detects the elapsed time T3 between the input timing of a reference signal described later and the rear end passage timing of the sheet A based on the output signal of the edge detection sensor 50B, and determines the elapsed time T3 and the setting method. A detection program for detecting a registration deviation based on a difference from a reference elapsed time Tp described later is stored.

The control section 40 stores a detection condition setting program for setting a registration deviation detection condition of the detection program.
The setting is automatically performed based on 0B and the input signal from the reference sensor 52B.

FIG. 11 shows a method for setting a registration deviation detection condition of the image forming apparatus having the above-described configuration.
This will be described in detail with reference to the flowchart shown in FIG.

First, a test signal is input to the control unit 40 by an operator input from the operation unit 42 (step 200). Based on this test signal, a drive signal is transmitted from the control unit 40 to the transport system of the apparatus, and the paper A is transported from the paper supply unit 14 to the image forming unit 18 (Step 202). At the same time, a reference image creation signal (image data of the reference image) is output to the optical scanning device 32 (step 204).

When the sheet A passes through the conveyance abnormality detection section 16 in the conveyance path 12, the edge detection sensor 50B
Based on the detection signal, the control unit 40 receives the reference signal (the test signal in the present embodiment) from the input of the end detection sensor 50.
The elapsed time T3 of the trailing edge detection timing of the sheet B of FIG.
(See (B)) is calculated (step 206).

Subsequently, when the sheet A reaches the transfer section 20, an image is formed. Here, based on the image data of the test image described above, a rectangular black reference image 54 is placed at a predetermined timing at the position of the sheet A corresponding to the position of the reference sensor 52B in the width direction of the sheet A.
B is formed (see FIG. 10A).

Further, when the sheet A on which the reference image 54B is formed reaches the correction reference section 22, the control section 40 causes the control section 40 to output the reference image 54B from the leading end of the sheet A based on the output signal of the edge detection sensor 52B. The transit time T4 to the rear end is obtained (see FIG. 10B) (step 2).
08).

Next, the control section 40 reads a theoretically determined set passage time Tr from the end of the sheet to the rear end of the reference image 54B passing through the reference sensor 52B (step 210).

Subsequently, the passage time T4 and the set passage time Tr
It is determined whether or not matches (step 212).

The transit time T4 does not depend on the mounting error or sensitivity difference of the reference sensor 52B. That is,
As shown in FIG. 10 (A), it depends purely on the position of the reference image 54B on the paper A. Therefore, the presence or absence of registration deviation can be determined by comparing with the set transit time Tr.

That is, the passage time T4 and the set passage time T
When r matches (T4 = Tr), there is no registration deviation. In this case, the elapsed time T
3 is set as the set elapsed time Tp (step 214).
Since the registration error does not occur in the case of the elapsed time T3, the elapsed time T3 is set as a reference value of the registration error detection.

Further, in step 212, if the transit time T4 is different from the set transit time Tr, that is, if a registration deviation has occurred, a time (Tr-T4) corresponding to the registration deviation amount elapses. The value subtracted from the time T3 is set as the set elapsed time Tp (step 216).

As described above, when the set elapsed time Tp (registration deviation detection condition) is set, a message indicating the end of the setting is displayed on the display 44 and the setting is ended (step 218).

As described above, in the present embodiment, only the reference sensor 52B is attached to the transport path 12 of the image forming apparatus 10 with high accuracy, and the reference image 54B is formed on a sheet. , It is possible to accurately set a conveyance abnormality (registration deviation) detection condition.

In particular, since the reference sensor 52B is mounted on the image forming apparatus 10 as a jig, it is possible to eliminate the influence of the difference in sensitivity of the sensor, the mounting error, etc., and to perform the correction with high accuracy.

Here, the first embodiment and the second embodiment have been described as different configurations, but they may be integrated. That is, in the configuration of the first embodiment, it is also possible to correct the skew detection condition and set the registration deviation detection condition.

[0067]

According to the present invention, it is possible to easily or accurately correct or set the abnormality detection condition of the conveyance abnormality detecting means by reliably removing the influence of the mounting error and the sensitivity difference of the end detecting means.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a method of correcting a skew detection condition according to a first embodiment of the present invention.

FIG. 2 is a schematic explanatory view of an image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is an explanatory plan view showing a positional relationship between an edge detection sensor and a reference sensor according to the first embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of an image forming apparatus according to the first embodiment of the present invention. .

FIG. 5A is a plan view illustrating a positional relationship between a sheet and an edge detection sensor in a conveyance path, and FIG. 5B is a timing chart illustrating a waveform of an output signal of each edge detection sensor when the sheet passes. It is a chart.

FIG. 6A is an explanatory plan view showing a positional relationship between a sheet and a reference sensor in a conveyance path, and FIG. 6B is a timing chart showing a waveform of an output signal of each reference sensor when the sheet passes.

FIG. 7A is an explanatory plan view showing a positional relationship between a sheet and an edge detection sensor in a conveyance path, and FIG. 7B is a timing chart showing a waveform of an output signal of each edge detection sensor when the sheet has passed; It is a chart.

8A is an explanatory plan view showing a positional relationship between a sheet and a reference sensor in a transport path, and FIG. 8B is a timing chart showing a waveform of an output signal of each reference sensor when the sheet passes.

FIG. 9A is an explanatory plan view showing a positional relationship between a sheet and an edge detection sensor in a transport path according to a second embodiment of the present invention, and FIG. 9B is an end detection sensor when the sheet has passed; 5 is a timing chart showing waveforms of an output signal and a test signal of FIG.

FIG. 10A is a plan view illustrating a positional relationship between a sheet and a reference sensor in a conveyance path according to a second embodiment of the present invention, and FIG. 10B is a plan view of an output signal of the reference sensor when the sheet passes. 6 is a timing chart showing a waveform.

FIG. 11 is a flowchart illustrating a method for setting a registration deviation detection condition according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus 12 ... Conveying path 18 ... Image forming part (image forming means) 40 ... Control part (correction means) 50A, 50B ... Edge detection sensor (edge detection means) 52A, 52B ... Reference sensor (edge) Detecting means) 54A, 54B ... reference image (measuring means)

Continued on front page F-term (reference) 2H027 DA20 DC00 DC04 DC05 EC03 EC06 EC07 EK10 GB07 HA12 2H072 AA03 AA09 AA16 AA24 AA29 AB28 CA01 3F048 AA01 AB01 BA05 BA14 BA20 BB03 BC01 CA09 CC03 DA06 DB04 DB06 DC05 EB24

Claims (4)

[Claims] In an image forming apparatus, edge detection of a sheet is detected by a plurality of edge detection means arranged in a straight line at predetermined intervals in a width direction orthogonal to a sheet conveyance direction on a conveyance path. A method of correcting conveyance error detecting means for detecting an error in sheet conveyance based on a timing shift amount, wherein a plurality of the edge detection means respectively detect end portions of a sheet conveyed on a conveyance path. And a second step of forming a plurality of the same reference images at the same timing by the image forming means at a position on the sheet corresponding to a position where the edge detecting means is provided in the width direction of the transport path. A plurality of measuring means are mounted on the transport path on the downstream side of the image forming means at a position corresponding to a position where the edge detecting means is disposed in the width direction, and a plurality of measuring means are provided in front of the edge of the sheet. A third step in which each measuring means measures a passing time until the reference image passes, and a shift amount of the detection timing by the plurality of end detecting means, and a shift amount of the passing time by the plurality of measuring means,
A fourth step of changing an abnormality detection condition of the transport abnormality detecting means so as to detect a transport error of the sheet based on a value obtained by adding or subtracting a difference between the two shift amounts to the shift amount of the detection timing. The correction method of the conveyance abnormality detection means of the image forming apparatus. 2. An image forming apparatus according to claim 1, wherein said image forming apparatus detects a registration error based on an elapsed time from a reference timing to an end detection timing of a sheet detected by an end detection unit disposed on the conveyance path. A first step of detecting an elapsed time from the reference timing to detecting an end of a sheet conveyed on the conveyance path by the end detection means; and A second step in which the image forming unit forms a reference image at a predetermined timing at a position on the sheet corresponding to a position where the edge detection unit is disposed in the width direction; Measuring means is mounted at a position corresponding to the position where the edge detection means is provided in the width direction in the conveyance path, and the distance from the edge of the paper to the reference image is measured. A third step in which the measuring means measures a passing time to pass, a difference between the passing time and a theoretical passing time is obtained, and a registration shift is detected based on a time obtained by adding or subtracting the difference to the elapsed time. A fourth step of setting an abnormality detection condition of the conveyance abnormality detection unit. The method of setting a conveyance abnormality detection unit of the image forming apparatus, comprising: 3. An image forming apparatus, wherein a conveyance abnormality detection condition of said conveyance abnormality detection means is corrected by the correction method according to claim 1. 4. An image forming apparatus, wherein a conveyance abnormality detection condition of the conveyance abnormality detection means is set by the setting method according to claim 2.