JP2022141424A - Image formation device - Google Patents

Abstract

To provide a technique that enables skew detection of a sheet by a simple constitution.SOLUTION: An image formation device includes: a transport path where a sheet is transported; a member that abuts a center part in a width direction that intersects with a transport direction; first timing detection means that detects first timing when the sheet passes through a first position on the transport path; an abutting member that has a first abutting part that abuts the sheet passing through a second position that is more downstream in the sheet transport direction on the transport path than the first position and can contact at least one end side in the sheet width direction and a second abutting part that can contact the other end side in the sheet width direction, and moves from a non-detection position to a detection position by abutting of the sheet on either the first abutting part or the second abutting part; second timing detection means that detects timing when the abutting member has moved to the detection position; and skew detection means that detects the skew of the sheet based on respective time differences.SELECTED DRAWING: Figure 2

Description

The present invention relates to a sheet feeding device, an image forming device, and a skew detection system.

A conventional sheet feeding apparatus includes a conveying mechanism that conveys a sheet placed on a tray and a plurality of sensors that detect skew of the conveyed sheet in the width direction perpendicular to the conveying direction. (Patent Document 1). In addition, there is a configuration in which two skew detection means are provided for one sheet width direction, and two or more sets of skew detection means are provided when these are set as one set, that is, four or more skew detection means are provided ( Patent document 2). However, with the configuration of the detecting means described in Japanese Patent Application Laid-Open No. 2002-200313, the size of the sheet for which skew feeding can be detected is limited. Further, in the detection configuration described in Patent Document 2, the number of detection units must be increased in order to widen the range of sheet sizes that can be handled.

Japanese Patent Application Laid-Open No. 2020-147408 Japanese Unexamined Patent Application Publication No. 2020-147409

SUMMARY OF THE INVENTION An object of the present invention is to provide a technology capable of accurately detecting sheet skew by obtaining detection information between sensors with a low-cost and simple configuration that can reduce the number of detection sensors.

In order to achieve the above object, the image forming apparatus of the present invention includes:
a conveying path for conveying the sheet;
A member that abuts on a central portion of the sheet in the width direction that intersects the sheet conveying direction, the sheet passing through the first position in the conveying path by contacting the center portion of the sheet in the width direction. a first timing detection means for detecting timing;
A contact portion that contacts a sheet passing through a second position downstream of the first position in the conveying direction of the sheet in the conveying path, the contact portion being at least one end portion of the sheet in the width direction. and a second contact portion capable of contacting the other end side of the sheet in the width direction, wherein the first contact portion and the a contact member configured to move from a non-detection position to a detection position when the sheet contacts at least one of the second contact portions;
a second timing detection means for detecting a second timing when the contact member moves to the detection position;
skew detection means for detecting skew of the sheet based on the time difference between the first timing and the second timing;
characterized by comprising
In order to achieve the above object, the image forming apparatus of the present invention includes:
a conveying path for conveying the sheet;
A member that abuts on a central portion of the sheet in the width direction that intersects the sheet conveying direction, the sheet passing through the first position in the conveying path by contacting the center portion of the sheet in the width direction. a first timing detection means for detecting timing;
a contact portion that contacts a sheet passing through a second position downstream of the first position in the conveying direction of the sheet in the conveying path, the contact portion being in contact with one end side of the sheet in the width direction; a contactable first contact portion and a second contact portion contactable with the other end side of the sheet in the width direction; a contact member configured to move from a non-detection position to a detection position by contacting the sheet with both of the contact portions of the
a second timing detection means for detecting a second timing when the contact member moves to the detection position;
skew detection means for detecting skew of the sheet based on the time difference between the first timing and the second timing;
characterized by comprising

According to the present invention, detection information between sensors can be obtained with a small number of detection sensors, a low cost, and a simple configuration, and skew feeding of a sheet can be accurately detected.

Schematic cross-sectional view showing an image forming apparatus according to Embodiment 1 Schematic cross-sectional view of a sheet conveying unit according to Embodiment 1 Schematic perspective view of a registration shutter unit according to the first embodiment. Operation diagram of the sheet conveying unit according to the first embodiment (at the time of contact with the register shutter) Operation diagram of the sheet conveying unit according to the first embodiment (at the time of passage through the register shutter) Schematic cross-sectional view of a sheet conveying unit according to Embodiment 2 Schematic perspective view of a paper width sensor unit according to the second embodiment Schematic perspective view of sheet conveying unit according to embodiment 2 Operation diagram of the paper width link sensor unit according to the third embodiment Flowchart diagram of side restriction set error determination according to the first embodiment Flowchart diagram of side restriction set mistake determination according to the fourth embodiment Functional block diagram according to the first embodiment Functional block diagram according to the fourth embodiment

<Example 1>
An image forming apparatus equipped with a sheet feeding device according to the present invention will be described below. Modes for carrying out the present invention will be exemplarily described in detail based on examples. However, the dimensions, materials, shapes, and relative arrangement of the components described in these examples should be appropriately changed according to the configuration of the device to which the invention is applied and various conditions. It is not intended to limit the scope to the following embodiments.

Here, an electrophotographic color laser printer (hereinafter referred to as LBP) will be described as an example of the image forming apparatus with reference to the drawings. Although the sheet feeding device of the embodiment of the present invention is applied to the LBP, the present invention is not limited to this, and may be applied to copiers, inkjet printers, and the like.

First, a schematic configuration of the LBP 100 as an image forming apparatus will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view of an LBP 100 according to an embodiment of the invention. First, the image forming portion 100A will be described in the conveying path from the formation of an image on the sheet S until the sheet S is conveyed to the discharge portion 113. FIG. An image forming unit 100A is provided in the LBP apparatus main body 100 and is an image forming unit that forms an image by electrophotography. The image forming section 100A has four photosensitive drums 101Y, 101M, 101C, and 101K for forming toner images of four colors of yellow, magenta, cyan, and black. An endless intermediate transfer belt 102 is in contact with these four photoreceptor drums and onto which the toner images formed on the four photoreceptor drums 101Y, 101M, 101C, and 101K are primarily transferred. A nip is formed from the inner peripheral side of the intermediate transfer belt 102 with respect to the photoreceptor drums 101Y, 101M, 101C, and 101K, and a potential difference is generated between the photoreceptor drums 101Y, 101M, 101C, and 101K and the intermediate transfer belt 102. This causes the toner image to be primarily transferred. Further, from primary transfer rollers 106Y, 106M, 106C, and 106K and a secondary transfer roller 105 that forms a nip with the outer peripheral side of the intermediate transfer belt 102 and secondarily transfers the image transferred to the intermediate transfer belt 102 onto the sheet S, It is configured.

When the image forming operation is started in the image forming section 100A, the laser scanner 103 irradiates the photosensitive drums 101Y, 101M, 101C, and 101K charged to a constant potential with light according to image signals. Then, electrostatic latent images are formed on the photosensitive drums 101Y, 101M, 101C, and 101K. Next, toner images (visible images) are formed on the photosensitive drums 101Y, 101M, 101C, and 101K by developing with the toner stored in the developing cartridges 104Y, 104M, 104C, and 104K. The toner images formed on the photosensitive drums 101Y, 101M, 101C, and 101K are then primarily transferred to the intermediate transfer belt 102, and the toner images on the intermediate transfer belt 102 are intermediately transferred to the secondary transfer portion. It is conveyed by belt 102 .

In parallel with such a toner image forming operation, sheets S are fed one by one from the sheet feeding device 20 . The sheet S is conveyed by the registration roller 30 to the secondary transfer portion formed by the nip between the intermediate transfer belt 102 and the secondary transfer roller 105 . Here, since the position of the sheet S in the sheet conveying direction needs to be aligned with the toner image formed on the intermediate transfer belt 102, the timing of the sheet S can be adjusted by controlling the conveying speed of the registration rollers 30. done. Then, the toner image is transferred from the intermediate transfer belt 102 to the sheet S by applying a bias to the secondary transfer roller 105 at the secondary transfer portion. The sheet S onto which the toner image has been transferred is then conveyed to fixing means 111 , and the toner image is fixed onto the sheet S by being heated and pressurized by the fixing means 111 . After the fixing, the sheet S is discharged by the discharge roller 112 to the discharge section 113 at the top of the apparatus.

Here, the sheet conveying section in this embodiment will be described in detail with reference to FIGS. 2, 3, 4A, and 4B. 2 is a schematic cross-sectional view of the sheet conveying portion according to the first embodiment, FIG. 3 is a schematic perspective view of the registration shutter 32 portion according to the first embodiment, and FIG. 4A is a contact sheet S of the sheet conveying portion according to the first embodiment. FIG. 4B is an operation diagram when the sheet S passes through the sheet conveying unit according to the first embodiment.

2, there are a registration roller 31 facing the registration roller 30, a registration shutter 32, a registration shutter holder 33, a registration sensor detecting section 34, and a registration sheet metal 35. FIG. Furthermore, a transport roller 39, a transport roller 40 facing the transport roller 39, a transport sensor 41, and a transport sensor detector 42 are arranged on the upstream side where these are arranged.

FIG. 4A(a) is a cross-sectional view of the vicinity of the registration shutter 32 immediately before the greatly skewed sheet comes into contact with the registration shutter 32, and FIG. 4A(b) is a registration shutter just before the greatly skewed sheet comes into contact with the registration shutter 32. Fig. 32 is a perspective view of the vicinity of 32; 4B(a) is a cross-sectional view of the vicinity of the registration shutter 32 immediately after the greatly skewed sheet comes into contact with the registration shutter 32 and passes through, and FIG. It is a perspective view near the registration shutter 32 immediately after passing in contact. 4A and 4B, some of the parts shown in FIG. 2 are not shown in order to explain the operation in an easy-to-understand manner.

First, the schematic configuration of the sheet conveying section will be described with reference to FIG. As shown in FIG. 2, a sheet fed from a sheet feeding device is guided to a nip formed by a conveying roller 39 and a conveying roller 40 and passes through the conveying roller 40 arranged near the nip. Thereafter, the sheet is conveyed to the registration shutter 32 through the conveying path formed by the upper conveying guide 38 and the lower conveying guide 37 . If the sheet is slightly skewed, the skew is corrected by the registration shutter 32, guided to the nip formed by the registration roller 30 and the registration roller 31, and sent to the downstream image forming section 100A and fixing means 111. and transported. The nip portion formed by the registration rollers 30 and the registration rollers 31 and the registration shutter 32 are arranged at fairly close positions in the sheet conveying direction.

Next, the configuration around the registration shutter 32 will be described with reference to FIG. The registration shutter 32 is engaged with the registration shutter holder 33 so as to be rotatable about the rotation center A with respect to the registration shutter holder 33 . The registration shutter holder 33 is attached to a registration sheet metal 35, and is urged by a registration biasing member 36, so that the three parts of the registration shutter 32, the registration shutter holder 33, and the registration sheet metal 35 can rotate about the rotation center B. configuration. Further, the registration shutter holder 33 has a downstream sensor light blocking portion X, and the downstream sensor light blocking portion X does not block the registration sensor detection portion 34 at the non-detection position where the registration shutter 32 is not rotated. Then, the conveyed sheet passes, the registration shutter 32 rotates (moves), and the downstream sensor light shielding portion X shields the registration sensor detection portion 34, whereby the rotation state of the registration shutter 32 is detected. The position at which the registration shutter 32 is rotated is defined as the detection position.

Further, the operation of the conveying roller 40 and the registration sensor when a skewed sheet is conveyed will be described with reference to FIGS. 2, 4A, and 4B. Here, it is assumed that sheet conveyance acceleration/deceleration control is not performed between the sheet conveying units, that is, between the conveying roller 39 and the registration roller 30 . First, as shown in FIG. 2, the conveying roller 40 provided at the first position in the sheet conveying path is arranged substantially in the center (central portion) with respect to the width direction intersecting the sheet conveying direction. Here, as the first timing detection means, a transport sensor detection section 42 composed of the transport roller 40, the upstream sensor light shielding section Y, and the transport sensor 41 is configured. The upstream sensor light shielding portion Y is a flag member that moves in contact with the sheet. The upstream sensor light shielding portion Y rotates when the central portion of the sheet in the width direction passes the first position in the transport path (first timing), and switches between the transmission and light shielding states of the transport sensor 41 . Note that the upstream sensor light shielding portion Y is arranged substantially in the center with respect to the sheet width direction. Therefore, the timing at which the upstream sensor light shielding portion Y rotates to shield the conveying sensor 41 is the same timing when a skewed sheet is conveyed and when a non-skewed sheet is conveyed. becomes. Therefore, it is possible to detect the skewed state of the sheet based on the time difference from the second detection timing, which differs in detection timing depending on the skewed state of the sheet.

Next, the operation of the second timing detection means is shown in FIGS. 4A and 4B. Here, as the second timing detection means, a registration sensor, a registration shutter 32, a registration sensor detection section 34 including a registration shutter holder 33 and a downstream sensor light shielding section X (for second timing detection), a registration sheet metal 35, and a registration urging member 36 are configured. The second timing detection means is provided at a second position downstream in the transport direction from the first position where the transport rollers 40 are located. The registration shutter 32 has a first contact portion with which one end side of the conveyed sheet S in the width direction contacts, and a second contact portion capable of contacting the other end side of the sheet S. It is an abutment member that abuts on S. Further, the first contact portion is provided so as to be able to contact a region closer to one end than the center portion in the width direction of the sheet, and the second contact portion is provided to contact the center portion in the width direction of the sheet. It is provided so as to be able to abut on a region closer to the other end than the other end. Further, the registration shutter 32 rotates when the contact portion comes into contact with the conveyed sheet, and the second timing of moving from the non-detection position to the detection position is detected by the downstream sensor light shielding portion X blocking the registration sensor. (second timing detection means).

The operation timing of the registration sensor is mainly divided into two operation timings depending on the amount of skew of the conveyed sheet. The first timing is a timing that is not significantly different from that for a non-skewed sheet. With respect to the amount of skew that can be corrected by the registration shutter 32 due to conveyance variations, the leading edge of the sheet that precedes in the conveyance direction first contacts the registration shutter 32 to form a loop in the conveyance path. After that, the leading edge of the sheet on the delayed side comes into contact with the registration shutter 32, and only after the leading edges of the sheets are aligned, the registration shutter 32 is retracted and rotated from the sheet being conveyed, so that the sheet is moved to the registration roller 30 on the downstream side. Sheets can be conveyed. Therefore, in the case of skew feeding that can be corrected by the registration shutter 32, the operation timing is not much different from that of a non-skewed sheet.

The second timing is the timing at which the registration sensor operates earlier than for a non-skewed sheet. This is because the leading edge of the preceding sheet S is conveyed around the contact portion of the registration shutter 32 without substantially forming a loop with respect to the amount of skew (large skew) that cannot be corrected by the registration shutter 32 . Occur. First, when a sheet S is conveyed whose far side is far ahead in the sheet width direction, the state shown in FIG. If the sheet is skewed by a correctable amount, the leading sheet back side forms a loop by the registration shutter 32 , and the registration biasing member 36 is applied until the leading edge of the sheet on the front side of the sheet comes into contact with the registration shutter 32 . The sheet S is dammed up by force. However, as shown in FIG. 4A, when the skew is large, the amount of loop formation inevitably becomes large. Then, in the loop forming space in the conveying path formed by the upper conveying guide 38 and the lower conveying guide 37, before the leading edge of the sheet on the front side of the sheet abuts on the registration shutter 32, the loop that must be formed on the back side. quantity is not formed. The reason for this is that the sheet S looped on the far side hits the upper conveying guide 38 immediately, and the reaction force of the sheet S immediately causes the registration shutter 32 to rotate. As a result, the registration shutter 32 is hardly able to correct the skew, and its operation timing is earlier than that for a non-skewed sheet.

Therefore, the timing for detecting the second timing is different between a sheet that is greatly skewed and a sheet that is not skewed. Therefore, if the time difference between the detection timings of the conveyance sensor detection unit 42 that detects the first timing and the registration sensor detection unit 34 that detects the second timing is compared for a non-skewed sheet and a skewed sheet, , skew can be detected. As described above, the first timing detects the timing at which the conveying roller 40 rotates, but since the position of the conveying roller 40 is arranged substantially in the center (central portion) with respect to the sheet width direction, the sheet travels greatly obliquely. The detection timing is the same for a skewed sheet and a non-skewed sheet. That is, in the sheet width direction, the passage of the sheet is detected by the first timing detection means at a position different from the contact position of the second timing detection means. This is the part where the timing of detection is the same for sheets that are not being fed. As the skew detection means, it is also possible to calculate an approximate amount of skew by calculation. become smaller.

One of the causes of the large skew of the sheet is that the side regulation 24 that regulates the width direction of the conveyed sheet in the cassette 23 (sheet containing portion) that accommodates a plurality of sheets is larger than the width of the conveyed sheet. There is a setting mistake that sets the sheet in a spread state. The purpose of this embodiment is to notify this. However, if the skew detection method described above detects a large skew of only one sheet and determines that it is due to a setting error, for example, the uppermost sheet when setting the sheet in the cassette 23 In some cases, only the paper is set incorrectly by the user, so there is a risk of false alarms. Therefore, in order to report with certain confidence without false reporting, it is necessary to process the detected skew in units of a certain unit by a specific algorithm.

An algorithm for this arithmetic processing will be described with reference to FIG. FIG. 9 is a flow chart showing the main flow up to notification of a side regulation set error. Here, the value of the time difference between the first timing by the transport sensor detection unit 42 and the second timing by the registration sensor detection unit 34 is defined as the T value. As described above, the T value when the sheet is greatly skewed is smaller than the T value when the sheet is not skewed. First, the T value is reset using the opening and closing of the cassette 23 as a trigger, and when the sheet feeding starts, the T value is acquired one by one and accumulated (a plurality of time difference values are acquired). Then, according to the principle described above, the T value of the least skewed sheet, that is, the sheet conveyed most straightly becomes the theoretical maximum value. value). After that, the difference between the T values other than the T_MAX value from the T_MAX value is calculated for a predetermined number of sheets, for example, 100 sheets, and the sum of each 100 sheets is defined as an index value (accumulated value of difference). This index value is a value that indicates the degree of skew of the sheet accommodated in the sheet accommodation portion, and if it exceeds a certain threshold, it is determined that there is a possibility of a side restriction setting error.

ここでＴ値の差分で１以下のものは搬送バラツキによる影響によるもので、サイド規制セットミスの判定正確度を上げるために、Ｔ値の差分を２乗してその寄与度を小さくしてしまってもよい。その場合の指標値は以下のような数式となる。

なお、Ｔ値の差分を用いた指標値とすることで、搬送センサ検知部４２に到達するまでの各搬送ローラアライメント等が要因で生じる斜行の影響を計算上でキャンセルできるメリットがある。また、耐久が進んで搬送ローラ３９が摩耗してきた場合においては、搬送ローラ３９径が小さくなるためＴ値が長くなるが、Ｔ値の差分を用いた指標値とすることで、閾値を耐久進行度合いによって変える必要もなく、固定で設定できるというメリットもある。また、紙種によってＴ値は変わってしまうが、所定の閾値は差分を取っているため
変える必要がなく、固定で設定できるというメリットもある。 If a predetermined number of sheets (for example, 100 or more) have not been passed and the opening/closing of the cassette 23 is detected, the number of data for calculating the index value is small and the reliability of determination is low. Therefore, UNKNOWN is notified without performing the side restriction set error determination, and the T value and T_MAX value for the number of sheets that have not reached the predetermined number are reset. Even if 100 or more sheets have not been passed, the opening and closing of the cassette 23 is not detected, and the sheet type discriminating means (not shown) detects that the sheet type does not change. For example, an index value is calculated to determine whether the side regulation is set incorrectly. Note that the predetermined number of sheets, for example, 100 sheets, does not necessarily have to be this number, and can be arbitrarily set depending on the detection accuracy. After that, based on the result of the side regulation set mistake determination, trouble shooting or the like is notified. As described above, the index values described above are mathematically represented as follows when the predetermined number of sheets is 100 sheets.

Here, the difference in the T value of 1 or less is due to the influence of conveyance variation, and in order to increase the accuracy of the determination of the side regulation set mistake, the difference in the T value is squared to reduce its contribution. may The index value in that case is expressed by the following formula.

By using the index value using the difference in the T value, there is an advantage that the influence of skew caused by factors such as the alignment of each conveying roller until reaching the conveying sensor detection unit 42 can be canceled in calculation. Further, when the transport roller 39 wears as the endurance progresses, the diameter of the transport roller 39 becomes smaller and the T value becomes longer. There is no need to change it depending on the degree, and there is also an advantage that it can be set fixedly. Also, although the T value changes depending on the paper type, there is an advantage that the predetermined threshold does not need to be changed because the difference is taken, and can be set as a fixed value.

Furthermore, since the index value obtained by the above method is different from the standard deviation and the dispersion value, which are values that indicate variations, for example, in the side regulation setting error state, the user can tilt the sheet bundle uniformly in one direction and set it in the cassette 23. Even if it has been done, it is possible to accurately report a setting mistake. In this case, if the standard deviation or variance value is used as an index value, the sheet will be skewed, but the skew amount is substantially constant and does not vary. Therefore, if the standard deviation or the variance value is used as the index value, it is not possible to correctly report the side regulation set error.

As described above, by arithmetically processing the T value and using it as an index value (accumulated value of the difference), side regulation setting mistakes can be reliably determined within the LBP device main body 100, and troubleshooting can be performed with a high degree of confidence. can do. As described above, the registration shutter 32 needs to be configured so that the registration sensor can be detected with high accuracy in order to match the transfer timing in the secondary transfer section. Efforts have been made to make Therefore, by using the registration sensor detection unit 34 as one of the means for calculating the T value, it is possible to obtain a T value with higher accuracy than when a normal conveyance sensor detection unit is used, and the skew detection accuracy is also improved. can be improved.

In this embodiment, the T value is calculated at the timing of detecting the leading edge of the sheet, but the T value may be calculated at the timing of detecting the trailing edge of the sheet. Alternatively, the distance between the transport sensor detection section 42 and the registration sensor detection section 34 may be calculated from the number of revolutions of a transport motor (not shown) that rotates the transport roller 39, and that value may be treated in the same manner as the T value.

As a comparative example, the contents of Patent Document 1 are shown. Japanese Patent Application Laid-Open No. 2002-200003 mainly includes a sheet detection sensor, a sheet detection sensor, a sheet detection sensor, and a paper feed tray, and the position of the sheet detection sensor is arranged at the center in the sheet width direction. At least two detection means are selected from a plurality of positions in accordance with the designation as to whether or not the width of the stacked sheets is uniform, and the sheet is conveyed based on the difference in the detection timing of the selected detection means. It determines an abnormal state such as skewed sheet feeding. However, when the sizes are mixed and the small size sheet is mixed, the small size sheet may not be conveyed to the position of the sheet detection sensor. In this case, skew feeding cannot be correctly detected using the sheet detection sensor and the sheet detection sensor. Therefore, one of a plurality of sensors provided in the width direction (the sheet detection sensor in this case) and the sheet detection sensor are used, and the approximate amount of skew is calculated based on the elapsed time of these sensors. .

However, in Japanese Patent Application Laid-Open No. 2002-200011, regardless of whether the size of the sheet passed by the user is small or large, a plurality of detection means must be provided at one detection position, which increases the cost. In addition, means for determining whether or not small-size sheets are mixed and determining which sheet detection sensor is to be used at one detection position is required, which increases the cost.

Further, in Japanese Patent Application Laid-Open No. 2002-100002, at least two or more sets of skew detection means including detection units in the main scanning direction are provided so as to form a pair centering on the central portion in the width direction of the document. Each set includes a set capable of detecting only a narrow document and a set capable of detecting a wide document as well. The reason why it is used according to the width of the document is to accurately detect skew. In this manner, by maximizing the distance between the two sensors in the width direction with respect to the width of the sheet to be passed, skew feeding can be detected with high accuracy.

However, if the sensor interval in the document width direction is increased in order to increase the skew detection accuracy, small-sized documents cannot be detected. higher cost.

In the present embodiment, the number of detection sensors is reduced compared to the skew detection means of prior art documents 1 and 2, and detection information between sensors is obtained with a low-cost and simple configuration, thereby accurately detecting the skew of a sheet. It is configured to be able to detect lines.

A control block of this embodiment will be described with reference to FIG. Here, only the part related to the present embodiment is extracted and explained. In the image forming apparatus 500 , the signals of the first timing detection means 511 in the sheet conveying path 510 and the signals of the second timing detection means 513 by the contact member 512 are input to the skew detection section 515 . These signals are input to the arithmetic processing unit 514 in the skew detection unit 515, and the arithmetic processing described above is performed. Then, when skew of the sheet is detected as a result of the arithmetic processing, a signal is input to the notification unit 530 . The control unit 520 also has a CPU 521 that controls various operations, a RAM 522 that temporarily stores control data, and a ROM 523 that stores programs and control tables required for operations in a non-volatile manner. 500 control.

<Example 2>
A second embodiment will be described with reference to FIGS. 5 and 6. FIG. FIG. 5 is a schematic cross-sectional view of a sheet conveying section according to the second embodiment, and FIG. 6 is a schematic perspective view of a paper width sensor 52 section according to the second embodiment. The same reference numerals are given to the portions that overlap with the description of the above-described embodiment, and the description thereof is omitted. As shown in FIGS. 5 and 6, this embodiment is characterized by using a paper width sensor detection section 53 instead of the registration sensor detection section 34 used for calculating the T value in the first embodiment.

In FIG. 5, the configuration of the transport sensor detection unit 42 located upstream of the paper width sensor detection unit 53 is the same as that of the first embodiment, so the description thereof will be omitted. As shown in FIGS. 5 and 6, the paper width sensor 52 has two contact portions that contact the sheet, a rear 52R of the paper width sensor contact portion, a front 52F of the paper width sensor contact portion, and a downstream sensor light shielding portion X. have. Then, it is urged by the paper width sensor urging member 54 and supported so as to be rotatable about the center of rotation C. As shown in FIG. Here, for example, a sheet that is greatly skewed with its back side in the sheet width direction first is conveyed and comes into contact with the back 52R of the sheet width sensor abutment portion, and the front edge of the sheet on the front side in the sheet width direction is aligned with the front 52F of the sheet width sensor abutment portion. The sheet width sensor 52 rotates due to the sheet conveying force even if it is not in contact. Then, the rotation state is detected by the paper width sensor detecting portion 53 . As a result, in this embodiment, the T value in the skewed state is smaller than the T value in the non-skewed state, which is the same as in the first embodiment. In this embodiment, the index value is calculated by this configuration as the second timing detection means. The algorithm for judging the side regulation set mistake is also the same as that of the first embodiment.

As described above, in the present embodiment as well, it is possible to reliably determine the side restriction setting error in the LBP apparatus main body 100 by using the index value. In addition, in this embodiment, the position of the registration shutter 32 can be arbitrarily set, such as arranging it upstream of the paper width sensor 52 in the conveying direction. This is because, as described in the first embodiment, it is difficult to correct skew by the registration shutter 32 in the case of large skew. For example, in this embodiment, the transport sensor 41, the registration shutter 32, and the paper width sensor 52 are arranged from the upstream side in the transport direction. is placed in Then, when the conveyed sheet is greatly skewed, the skew is not corrected by the registration shutter 32, so the sheet width sensor 52 can detect the skew of the sheet.

<Example 3>
This embodiment will be described with reference to FIGS. 7 and 8. FIG. FIG. 7 is a schematic perspective view of the sheet conveying section according to the third embodiment, and FIG. 8 is an operation diagram of the paper width link sensor 74 section according to the third embodiment. Reference numeral 72 denotes a back paper width flag, 73 a front paper width flag, and 74 a paper width link sensor. The paper width link sensor 74 has a downstream sensor light shielding portion X. As shown in FIG. The same reference numerals are given to the portions that overlap with the description of the above-described embodiment, and the description thereof is omitted.

As shown in FIGS. 7 and 8, this embodiment is characterized by using a rear paper width flag 72, a front paper width flag 73, and a paper width link sensor 74 instead of the registration shutter 32 used in the first embodiment. In FIG. 7, the operations of the paper width flag front 73, the paper width flag rear 72, and the paper width link sensor 74 upstream of the paper width link sensor 74 function as first timing detection means, and have the same function as the conveyance sensor 41 in the first embodiment. omitted. First, the operation of the paper width flag back 72, the paper width flag front 73, and the paper width link sensor 74 will be described with reference to FIG. FIG. 8(a) shows the home position state (the sheet is not conveyed) of each of the paper width flag back 72, the paper width flag front 73, and the paper width link sensor 74. FIG. The paper width flag rear 72 is rotated clockwise by the paper width flag rear urging member 76, the paper width flag front 73 is rotated clockwise by the paper width flag front urging member 77, and the paper width link sensor 74 is rotated counterclockwise by the paper width link sensor urging member 78. held in that position. The biasing force of the paper width link sensor biasing member 78 biasing in the counterclockwise direction is the biasing force of the paper width flag rear biasing member 76 biasing in the clockwise direction, and the biasing force of the paper width flag front biasing member 77 is set smaller than the biasing force of

Here, for example, when a greatly skewed sheet with the far side in the sheet width direction leading is conveyed, and the leading edge of the leading sheet comes in contact with and passes through the paper width flag depth 72, the paper width flag depth 72 is in the state shown in FIG. 8B. . At this point, the front paper width flag 73 is not in contact with the leading edge of the sheet on the delayed side, and the contact portion α between the rear paper width flag 72 and the paper width link sensor 74 is separated, but the front paper width flag 73 and the paper width link sensor 74 are separated. The contact portion β is in contact. Since the biasing force of the paper width link sensor biasing member 78 is smaller than the biasing force of the paper width flag front biasing member 77, the position of the paper width link sensor 74 is maintained unchanged from the state shown in (a). After that, when the greatly skewed sheet is further conveyed and the leading edge of the sheet on the side behind the front paper width flag 73 abuts, the front paper width flag 73 is in the state shown in FIG. 8(c). At the same time, the paper width link sensor 74 also operates following the contact portion β of the front paper width flag 73, resulting in the state shown in FIG. 8(c). As shown in FIG. 8C, when both the paper width flag back 72 and the paper width flag front 73 fall down, the downstream sensor light shielding portion X of the paper width link sensor 74 moves for the first time to detect the paper width link sensor. It transmits light through the portion 75 and detects the rotation state of the paper width link sensor 74 .

以上述べたように、本実施例で示したセンサ同士をリンクさせた構成においても、指標値を利用してサイド規制セットミスを確実にＬＢＰ装置本体１００内で判定することが可能である。 Therefore, in this embodiment, unlike the first and second embodiments, the T value in the case of large skew is larger than the T value in the case of non-skew. Therefore, the reference data described in Example 1 should be changed to the MIN value instead of the MAX value of the T value. Since the reference data is changed to the MIN value, the index value described in Example 1 may become a negative value if not squared. Therefore, in this embodiment, the following formula is used for the index value, but the basic algorithm for judging the side restriction set error is the same as in the first embodiment.

As described above, even in the configuration in which the sensors are linked as shown in the present embodiment, it is possible to reliably determine the side restriction setting error in the LBP apparatus main body 100 using the index value.

<Example 4>
A fourth embodiment of the image forming apparatus according to the present invention will be described with reference to FIG. FIG. 10 is a flow chart showing the main flow up to notification of a side restriction set error in this embodiment. The same reference numerals are given to the portions that overlap with the description of the above-described embodiment, and the description thereof is omitted.

In Example 1, the side regulation set mistake determination as shown in FIG. It is characterized by performing analysis. As shown in FIG. 10, this embodiment comprises control by an image forming apparatus 500 in the LBP apparatus main body 100, and an analysis apparatus 501 and a management office 502 outside the LBP apparatus main body 100. FIG. As shown in FIG. 10 , data accumulated in image forming apparatus 500 is transmitted from a communication unit (not shown) in LBP apparatus main body 100 to analysis apparatus 501 outside LBP apparatus main body 100 . In analysis device 501, the transmitted data is received by a communication unit (not shown) in analysis device 501, and analyzed according to the algorithm shown in FIG. The analysis device 501 is equipped with a CPU with higher performance than the CPU in the LBP device main body 100 and a large-capacity memory, and is capable of analyzing large-scale data. Therefore, when the number of sheets to be passed increases and the amount of data to be handled increases, the processing load on the CPU and memory in the LBP device main body 100 becomes excessive, and skew detection analysis may become difficult. Therefore, a large amount of data can be processed by performing skew detection analysis with the high-performance analysis device 501 described above.

The results of analysis and determination are displayed on a display unit (not shown) provided in the analysis device 501, and are transmitted from a communication unit (not shown) in the analysis device 501 to the management office 502. It is also displayed on the provided display unit (not shown). Regarding the display contents, for example, the display of the analysis device 501 is a specific index value and an OK or NG judgment, while the display of the management office 502 is "Possibility that the side regulation 24 is not set correctly. Please check it because there is", it will be more specific. As described above, in this embodiment, the analysis of the detected oblique data is performed by the high-performance analysis device 501 outside the LBP apparatus main body 100, making it possible to handle more data.

A control block of this embodiment will be described with reference to FIG. Here, only the part related to the present embodiment is extracted and explained. In the image forming apparatus 500 , the signals of the first timing detection means 511 in the sheet conveying path 510 and the signals of the second timing detection means 513 by the contact member 512 are input to the time difference acquisition section 516 in the control section 520 . . A signal from the time difference acquisition unit 516 is input to the arithmetic processing unit 534 in the analysis device 501 connected to the image forming apparatus 500 . In the arithmetic processing unit 534, the arithmetic processing described above is performed, and when skew of the sheet is detected as a result of the arithmetic processing, a signal is input to the control center 502, and the skew is notified by the control center 502. be. Furthermore, the analysis device 501 has a CPU 531, a RAM 532, and a ROM 533 that have higher performance than the image forming device 500, and can process a large amount of data.

30: registration roller, 32: registration shutter, 37: lower transport guide, 38: upper transport guide, 39: transport roller, 40: transport roller, 41: transport sensor, 42: transport sensor detector, S: sheet, A, B , C: rotation center, X: downstream sensor light shielding part, Y: upstream sensor light shielding part

Claims (9)

a conveying path for conveying the sheet;
A member that abuts on a central portion of the sheet in the width direction that intersects the sheet conveying direction, the sheet passing through the first position in the conveying path by contacting the center portion of the sheet in the width direction. a first timing detection means for detecting timing;
A contact portion that contacts a sheet passing through a second position downstream of the first position in the conveying direction of the sheet in the conveying path, the contact portion being at least one end portion of the sheet in the width direction. and a second contact portion capable of contacting the other end side of the sheet in the width direction, wherein the first contact portion and the a contact member configured to move from a non-detection position to a detection position when the sheet contacts at least one of the second contact portions;
a second timing detection means for detecting a second timing when the contact member moves to the detection position;
skew detection means for detecting skew of the sheet based on the time difference between the first timing and the second timing;
An image forming apparatus comprising: The first contact portion is provided so as to contact a region closer to the one end than the central portion in the width direction of the sheet,
2. The image forming apparatus according to claim 1, wherein the second contact portion is provided so as to contact a region of the sheet closer to the other end than the center portion in the width direction. The first timing detection means detects the timing at which a portion of the sheet at which the first contact portion and the second contact portion do not contact each other passes through the first position as the first timing. 3. The image forming apparatus according to claim 1, wherein the image forming apparatus detects as . a conveying path for conveying the sheet;
A member that abuts on a central portion of the sheet in the width direction that intersects the sheet conveying direction, the sheet passing through the first position in the conveying path by contacting the center portion of the sheet in the width direction. a first timing detection means for detecting timing;
a contact portion that contacts a sheet passing through a second position downstream of the first position in the conveying direction of the sheet in the conveying path, the contact portion being in contact with one end side of the sheet in the width direction; a contactable first contact portion and a second contact portion contactable with the other end side of the sheet in the width direction; a contact member configured to move from a non-detection position to a detection position by contacting the sheet with both of the contact portions of the
a second timing detection means for detecting a second timing when the contact member moves to the detection position;
skew detection means for detecting skew of the sheet based on the time difference between the first timing and the second timing;
An image forming apparatus comprising: The first contact portion is provided so as to contact a region closer to the one end than the central portion in the width direction of the sheet,
5. The image forming apparatus according to claim 4, wherein the second contact portion is provided so as to be able to contact an area of the sheet closer to the other end than the center portion in the width direction. The first timing detection means detects the timing at which a portion of the sheet at which the first contact portion and the second contact portion do not contact each other passes through the first position as the first timing. 6. The image forming apparatus according to claim 4, wherein the image forming apparatus detects as . 7. The first timing detection means detects, as the first timing, the timing at which the center portion of the sheet in the width direction passes through the first position. 1. The image forming apparatus according to item 1 or 1. 8. The method according to any one of claims 1 to 7, wherein the skew detection means detects that the sheet is skewed when the value of the time difference is different from the value when the sheet is not skewed. The image forming apparatus according to any one of items 1 to 3. further comprising a sheet storage unit that stores a plurality of sheets to be transported along the transport path;
The skew detecting means is
obtaining the value of the time difference for each of the plurality of sheets conveyed from the sheet storage unit;
obtaining, as a comparative value, the value of the time difference with the lowest degree of skew of the sheet from among the plurality of values of the time difference;
obtaining a difference between the comparison value and a value other than the lowest time difference value among the plurality of time difference values;
The integrated value of the plurality of differences is compared with a predetermined threshold value as a value indicating the degree of skew of the sheet accommodated in the sheet accommodating portion, and if the value exceeds the predetermined threshold value, the sheet 9. The image forming apparatus according to any one of claims 1 to 8, wherein it is determined that the sheet accommodated in the accommodation unit is skewed.

Images