JP2011190040A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of detecting the size in every direction. <P>SOLUTION: The image forming device includes an opening/closing detection means detecting the opening/closing of a tray, a paper sheet presence/absence detection means detecting the presence/absence of any paper sheet in the tray, an end face detection means detecting end faces of paper sheets, a fence for aligning the end faces of the paper sheets, a position determining means which moves the fence when the opening/closing detection means detects that the tray is closed, and the paper sheet presence/absence detection means detects that paper sheets are present, and automatically determines the position of the fence when the end face detection means detects the end faces of the paper sheets, and a size measuring means for automatically measuring the size in the main scanning direction of the paper sheet and the size of the sub scanning direction of the paper sheet based on the movement of the fence by the position determining means. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus including a paper feed tray for feeding paper.

  For example, when printing is performed by an image forming apparatus such as a printer or an MFP (Multifunction Peripheral), the output paper is changed according to the purpose. For this reason, diversification of paper feed is required in image forming apparatuses.

  In order to diversify the paper feed, there is a method of using a multi-stage construction of paper feed trays, but the cost increases. Therefore, it is desirable to be able to print various types of paper using only one paper feed tray as much as possible. Therefore, it is required to have a configuration that can arbitrarily change the paper even with only one paper feed tray.

  As an example of such a configuration, there is a method of installing a fence in the paper feed tray. In this method, when the printing paper is changed, the user manually moves the fence to match the fence with the paper. In this way, even when using paper of various sizes, it is possible to align the sheets, and it is possible to prevent image misalignment due to misalignment of the sheets and paper jam. For example, Patent Document 1 discloses a configuration in which the movement of the side-direction fence and the end-direction fence and the display of the paper size by the size display unit are linked in order to simplify the fence setting when changing the paper. Yes.

  However, in the above method, it is necessary to manually move the fence, which makes the user troublesome. Therefore, Patent Document 2 discloses a configuration in which a fence is provided with a sensor so that the size of the installed paper is automatically detected, and the position of the side fence can be automatically adjusted according to the paper size. Yes. This configuration does not require manual operation by the user.

  However, in the configuration disclosed in Patent Document 2, automatic size detection in both main scanning and sub-scanning directions cannot be performed. Further, in the automatic size detection by the sensor provided in the fence, the sheet length value itself is not measured, but the range in which the length falls is measured. Therefore, since only the approximate length is known, there is no choice but to approximate the neighborhood size, but Patent Document 2 does not define a method for approximating the fixed size after size measurement. In addition, the automatic size detection by the sensor provided in the fence cannot automatically detect the paper size when setting a non-standard size paper. However, in Patent Document 2, the size detection when setting a non-standard size paper is specified. Not. For this reason, the configuration disclosed in Patent Document 2 has difficulty in size detection accuracy.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus capable of performing size detection in all directions.

  In order to solve the above-described problems, an image forming apparatus according to the present invention includes an open / close detection unit that detects opening / closing of a tray, a sheet presence / absence detection unit that detects presence / absence of a sheet in the tray, and an end surface that detects an end surface of the sheet. Detecting means, a fence for aligning the end surfaces of the paper, and detecting that the tray is closed by the open / close detecting means, and moving the fence when the paper presence detecting means detects that the paper is present A position determining unit that automatically determines the position of the fence when the end surface of the sheet is detected by the end surface detecting unit; and a main scanning direction of the sheet based on a movement amount of the fence by the position determining unit And size measuring means for automatically measuring the size in the sub-scanning direction and the size in the sub-scanning direction.

  According to the present invention, size detection in all directions can be performed.

FIG. 6 is a diagram illustrating an example of processing operation in the image forming apparatus according to the embodiment of the present invention. FIG. 4 is a diagram illustrating a relationship between a sheet in a tray and a fence in the image forming apparatus according to the embodiment of the present invention. FIG. 5 is a diagram illustrating a relationship between a fence and a sheet end surface detection mechanism in the image forming apparatus according to the embodiment of the present invention. FIG. 6 is a diagram illustrating an example of processing operation in the image forming apparatus according to the embodiment of the present invention. FIG. 6 is a diagram illustrating an example of processing operation in the image forming apparatus according to the embodiment of the present invention. It is a figure which shows the example of the skew detection mechanism in the image forming apparatus which concerns on embodiment of this invention. FIG. 3 is a diagram illustrating an example of a skew correction mechanism in the image forming apparatus according to the embodiment of the present invention.

  An embodiment of the present invention will be described. Specifically, the process has the following characteristics when changing paper in the paper feed tray. In short, the present invention automatically moves the side-direction fence and the end-direction fence to the home position (waiting at a position wider than the maximum paper size that can be stored in the tray) when the tray is opened. When the door is closed, the side fence and the end fence are automatically moved from the home position to the paper side, the fence position is determined when the paper is detected, and the size confirmation control is automatically performed from the fence movement distance. It has become a feature. The above features will be specifically described with reference to the following drawings.

<First Embodiment>
An example of processing operation in the image forming apparatus according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram illustrating a processing operation example in the image forming apparatus according to the first embodiment. The processing operation shown in FIG. 1 is an example of a processing operation performed by the image forming apparatus when a sheet in the tray of the image forming apparatus is replenished or changed. FIG. 2 is a diagram showing the relationship between the paper in the tray and the fence, and FIG. 3 is a diagram showing the relationship between the fence and the paper end surface detection mechanism.

  First, the user pulls out the tray (S100). As the tray is pulled out, the fence moves to the home position of the fence (S200). The home position is a position outside the maximum printable paper size so that various paper sizes can be placed in the tray. A mechanical configuration is desirable in which the side fence 1 and the end fence 2 automatically move in conjunction with the operation of pulling out the tray. This writes to the configuration.

  Work such as replenishment and change of paper to the tray pulled out by the user is performed, and the tray is reset to the original position before being pulled out (S300).

  The system checks whether there is a sheet in the tray (S400). If there is no sheet in the reset tray (S400, No), it is not necessary to move the fence, and the process ends.

  If there is paper in the reset tray (400, Yes), the system performs a fence positioning operation (S501 to S503). This positioning operation is performed by both the side fence 1 and the end fence 2.

  The fence is moved to the paper side by the rotation of the motor (S501).

  It is determined whether the sheet end face has been detected (S502). As shown in FIG. 3, the fence includes a detection mechanism that detects an end surface of the sheet. The detection of the sheet end face is the determination point for fence positioning.

  In the case of the side fence 1, the fence position cannot be determined until the left and right end faces of the pair of sheets are detected. However, in the case of the end fence 2, a predetermined fixed position is determined in advance on the one end face of the pair. Therefore, the position of the fence can be determined by detecting one end surface of the paper.

  If the detection timings of the left and right end faces of the pair of sheets are different in the side fence 1, the sheets are placed out of alignment in the tray, but the fence continues to move until both end faces are detected. As a result, the sheet can be slid in accordance with the movement of the fence, so that the misalignment can be corrected and aligned. At this time, the movement distance from the home position of each side fence 1 becomes equal distance on either side.

  If the sheet end face is detected (S502, Yes), the fence is stopped after fine adjustment of the remaining moving distance of the fence (S503).

  When the distance between the fence and the paper is too short, that is, when the fence pushes the paper too much, the jam between the paper and the fence is induced by the friction between the paper and the fence. On the other hand, when the distance between the fence and the paper is too long, the paper is set in an oblique state, which causes a skew.

  Therefore, it is beneficial to finely adjust the distance between the fence and the paper to stop the fence. It is desirable that the adjustment direction can be both a shrinking direction and a widening direction. If the distance between the final fence after fine adjustment and the paper is, for example, as shown in FIG. 3, the main scanning direction is A1 [mm] and the sub-scanning direction is A2 [mm], these values are The data is stored in a nonvolatile storage medium (for example, NVRAM) provided in the image forming apparatus 100. This stored value can be changed. In this way, it is possible to cope with the situation.

  In addition, it is desirable that the fence positioning control be performed with high accuracy and speed. However, increasing the moving speed of the fence means that the positioning accuracy is adversely affected. Therefore, this speed is stored in a nonvolatile storage medium (for example, NVRAM) provided in the image forming apparatus so that the speed value can be changed. By doing so, it is possible to cope with the situation.

  The system performs a paper size calculation process (S600).

The paper size can be detected by calculating the amount of movement of the fence from the home position. The amount of movement of the fence is calculated from, for example, the fence movement speed and the fence movement time. If the fence movement time is Ftime [s], the fence movement speed is Fspeed [mm / s], and the fence movement amount is Fdistance [mm], the formula for calculating the fence movement amount is as follows.
Ftime × Fspeed = Fdistance

As shown in FIG. 2, the automatically detected paper size is set to main scanning: X1 [mm], sub-scanning: X2 [mm], and the distance to the fence home position is set to main scanning: HP1 [mm], sub-scanning. : HP2 [mm], fence movement amount is main scanning: F1 [mm], sub-scanning: F2 [mm], and the final distance between the fence and the paper after fine adjustment in step S107 is main scanning: A1 [ mm], sub-scan: A2 [mm], the paper size calculation formula is as follows.
X1 = HP1- {F1 + (A1 × 2)}
X2 = HP2- {F2 + A2}

  The system performs size abnormality determination processing (S701, S702).

  The user does not always set a printable size. For this reason, the calculated size is not always a printable size. Therefore, when a paper that does not fall within the printable size range is set, the user is prompted to reset the paper appropriately.

  It is determined whether it is a printable size (S701). Since the printable size is determined in advance by the system, whether or not the printable size is determined is determined by the following.

As shown in FIG. 2, the automatically detected paper size is main scanning: X1 [mm], sub-scanning: X2 [mm], the minimum printable size is main scanning: α1 [mm], and sub-scanning: α2 [mm] ], And the maximum printable size is set to β1 [mm] for main scanning and β2 [mm] for sub-scanning,
X1 <α1, X1> β1 X2 <α2, X2> β2
If any one of the formulas is satisfied, it is determined that the printable size is not satisfied.

  If it does not correspond to the printable size guaranteed by the system (S701, No), the user is prompted to reset paper appropriately (S702). Specifically, an operation such as displaying an alert is performed.

  The system performs size determination processing (S801 to S805). It is necessary to determine the actual print size from the calculated size.

  It is confirmed whether the setting is fixed or non-standard (S801). The calculated size includes an error due to the accuracy at the time of end face detection and the calculation accuracy. Therefore, when the paper is a standard size, it is possible to perform stable printing by ignoring the error and approximating the standard size.

  If it is an irregular size setting (S801, No), an irregular size paper is set as a size determination process (S802). In this case, the previously calculated size is set as the main scanning and sub-scanning sizes as they are. When the automatically detected paper size is set to main scanning: X1 [mm] and sub-scanning: X2 [mm], the final size is also set to main scanning: X1 [mm] and sub-scanning: X2 [mm].

  When it is the standard size setting (S801, Yes), the standard size paper is set as the size determination process (S803). Here, the calculated size is replaced with a standard size that is determined to be most appropriate depending on whether the calculated size is within the main scanning or sub-scanning range.

The automatically detected paper size is main scanning: X1 [mm], sub-scanning: X2 [mm], the standard size is main scanning: C1 [mm], sub-scanning: C2 [mm], and the conversion margin is M [ mm]
C1-M <X1 <C1 + M C2-M <X2 <C2 + M
Accordingly, it can be determined that the most appropriate standard size is when both X1 and X2 satisfy the equation. Therefore, the determined size is set to main scanning: C1 [mm] and sub-scanning: C2 [mm] on condition that both of the above expressions are satisfied.

  For C1 and C2, all standard size values that can be printed by the system are sequentially substituted. M is assumed to be as small as possible so that a plurality of fixed sizes do not satisfy the above formula. The value that M can take depends on the accuracy and calculation accuracy at the time of end face detection, that is, the mechanical configuration and the hardware configuration. Therefore, if the conversion margin: M [mm] is stored in a non-volatile storage medium (for example, NVRAM) of the image forming apparatus and this value can be changed, it is possible to cope with the situation. .

  It is determined whether the size has been determined (S804). When the size is determined in step S803, there is not necessarily a fixed size that matches the fixed size setting. Therefore, after the size determination process in step S113, it is determined whether the size has been determined. If not yet determined (No in S804), the process proceeds to the next process.

It is determined whether or not to convert to an indefinite form (S805). In step S803, if an appropriate standard size is not found even after performing the size determination process, it is determined whether or not to convert to an irregular size.
When converting to an indeterminate form (S805, Yes), the original setting is changed to an indeterminate form, and an indefinite form size determination process is performed (S802). When not converting to an indeterminate form (S805, No), the user is prompted to reset paper (S702).

  With the above control, it is possible to automatically perform “all processes from fence movement control to paper size abnormality detection and size determination processing” associated with the paper change in the tray.

  Thus, by automating the movement of the fence in the tray, it is possible to greatly save the user's trouble when changing the paper. In the present embodiment, automatic size detection in all directions is possible by automating fence movement, and the size detection accuracy is further improved. It can also detect irregular sizes. In addition, it is possible to cope with an abnormality when a non-printable size paper is placed.

<Second Embodiment>
4 and 5 are processing operation examples in the image forming apparatus according to the second embodiment. As shown in FIG. 6, the image forming apparatus according to the second embodiment has a configuration of the image forming apparatus according to the first embodiment. It has a configuration with a mechanism for detecting whether skew has occurred. With this configuration, when detecting paper, skew is detected, that is, whether the paper is tilted.If an unacceptable amount of skew occurs, abnormal control such as warning and automatic correction is performed. Do. By doing so, the second embodiment prevents a skew phenomenon that an image is printed obliquely with respect to the paper depending on how the paper is placed in the tray.

  The difference between the processing operation shown in FIG. 4 and the processing operation shown in FIG. 1 is only the fence positioning operation. That is, steps S100 to S400 and steps S600 to S805 of the processing operation shown in FIG. 4 are the same as steps S100 to S400 and steps S600 to S805 of the processing operation shown in FIG.

  The positioning operation in the processing operation illustrated in FIG. 4 is different from the processing operation illustrated in FIG. 1 in that the side fence 1 and the end fence 2 are not positioned in parallel but are performed in the order of the side fence 1 and the end fence 2 (S511). ~ S519).

  First, movement control of the side fence 1 is performed (S511 to S516).

  The side fence 1 is moved from the home position toward the paper (S511). The side fence 1 is moved to the paper side by the rotation of the motor.

  It is determined whether the sheet end face has been detected (S512). As shown in FIG. 3, the side fence 1 includes a detection mechanism that detects the end face of the sheet. The detection of the sheet end face is the determination point for fence positioning.

  In the case of the side fence 1, the fence position cannot be determined until the left and right end faces of the pair of sheets are detected. If the detection timings of the left and right end faces of the pair of sheets are different in the side fence 1, the sheets are placed out of alignment in the tray, but the fence continues to move until both end faces are detected. As a result, the sheet can be slid in accordance with the movement of the fence, so that the misalignment can be corrected and aligned. At this time, the movement distance from the home position of each side fence 1 becomes equal distance on either side.

  If the sheet end face is detected (S512, Yes), the side fence 1 is stopped after fine adjustment of the remaining moving distance of the side fence 1 (S513).

  When the distance between the side fence 1 and the sheet is too short, that is, when the side fence 1 is pushing the sheet too much, jamming is induced during conveyance due to friction between the sheet and the side fence 1. On the other hand, if the distance between the side fence 1 and the paper is too long, the paper is set in an oblique state, which causes a skew.

  Therefore, it is beneficial if the side fence 1 can be stopped by finely adjusting the distance between the side fence 1 and the sheet. It is desirable that the adjustment direction can be both a shrinking direction and a widening direction. For example, as shown in FIG. 3, when the final distance between the side fence 1 and the paper after fine adjustment is set to the main scanning direction: A1 [mm] and the sub-scanning direction: A2 [mm], The value is stored in a nonvolatile storage medium (for example, NVRAM) provided in the image forming apparatus 100. This stored value can be changed. In this way, it is possible to cope with the situation.

  Further, it is desirable that the positioning control of the side fence 1 is performed with high accuracy and speed. However, increasing the moving speed of the fence means that the positioning accuracy is adversely affected. Therefore, this speed is stored in a nonvolatile storage medium (for example, NVRAM) provided in the image forming apparatus so that the speed value can be changed. By doing so, it is possible to cope with the situation.

  A skew calculation process is performed (S514). Depending on how the user places the paper, there is a possibility that the paper is skewed, that is, a so-called skew has occurred. Therefore, in the present embodiment, the skew amount is calculated when the sheet end surface is detected when the side fence 1 is moved. As a mechanism for calculating the skew amount, for example, the mechanism shown in FIG. 6A and the mechanism shown in FIG.

  As shown in FIG. 6A, when there are a plurality of end face detection mechanisms on the same end face, if the paper is shifted, that is, if a skew is generated, the time difference until the end face is detected by the detection mechanism. Is born.

For example, assuming that the number of detection mechanisms is two on one end face, the skew amount can be obtained from the difference in detection distance at this time. If the detection distance difference is Sdif [mm], the detection time difference is Sdiftime [s], and the fence moving speed is Fspeed [mm / s], the calculation formula for the detection distance difference is as follows.
Sdiftime × Fspeed = Sdif

For example, if the skew amount is defined by an angle, assuming that the skew amount is θ [degree] and the distance between the two detection mechanisms is DtoD [mm], the skew amount calculation formula is as follows.
θ = arctan (Sdif / DtoD)

Further, as shown in FIG. 6B, in the case of a mechanism in which the side fence 1 rotates in accordance with the end face of the paper, if the paper is shifted, that is, if a skew occurs, the paper and the fence The fence rotates along the paper when it touches. If the skew amount is defined by an angle, for example, the rotation angle at this time becomes the skew amount. When the skew amount is θ [degree], the rotation distance of the central axis of the side fence 1 is Fl, and the distance from the central axis of the fence to the fence end is Fr, the calculation formula of the skew amount is as follows.
Fl = 2π × Fr × (θ / 360)
⇔ θ = (180 × Fl) / (π × Fr)

  It is determined whether the skew is within tolerance (S515). It is determined whether the calculated skew amount is within an allowable range. Since it is very difficult for the user to place the paper without inclining it a little, there is a process to correct the skew state placed obliquely in the image forming apparatus during printing even if it is placed in an oblique state. It is common. However, in a general process for correcting the skew state during printing that is pre-stored in the image forming apparatus, not only the correctable amount is determined but also the mechanism of the image forming apparatus, the conditions of the paper, and the like. Therefore, it is desirable that the calculated skew is equal to or less than the amount corrected during printing, and it is necessary to determine whether the skew amount is within an allowable range or not.

If the skew amount is θ [degree] and the skew tolerance is γ,
θ ≦ γ
If it is, it is determined that the skew is within tolerance. Further, the skew allowable value γ is preferably stored in a non-volatile storage medium (for example, NVRAM) included in the image forming apparatus so that the value can be changed. In this way, it is possible to cope with the situation.

  If the calculated skew amount is outside the permissible value compared with the permissible value (S515, No), the user is prompted to reset the paper (S702, FIG. 4). However, if the setting that does not prompt the resetting is made (S516, No), the process moves to the end-direction fence moving process.

  If there is a skew correction process associated with fence movement control, the sheet is rotated by a tray bottom plate turntable as shown in FIG. 7 in order to correct the calculated skew amount (S520). Further, since there is a possibility that a gap between the side fence 1 and the sheet may be formed after the bottom plate is rotated, the positioning process of the side fence 1 is performed once again.

  Next, movement control of the end fence 2 is performed (S517 to S519).

  The end fence 2 is moved from the home position toward the paper (S517).

  It is determined whether the sheet end face has been detected (S518).

  When the sheet end face is detected (S518, Yes), the end fence 2 is stopped after fine adjustment of the remaining moving distance of the end fence 2 (S519). The detection of the sheet end face is the determination point for fence positioning. In the case of the end fence 2, a predetermined fixed position is determined in advance for one end surface of the pair, so that the position of the end fence 2 can be determined by detecting one end surface of the sheet. However, when skew correction processing is performed, there may be a gap due to rotation between the front end side end surface in the paper transport direction and a predetermined fixed position. The fence is moved until both end surfaces of the sheet and the rear end are detected, and the leading edge of the sheet is moved to the fixed position by the pressing force of the end fence 2 so as to fill the empty gap.

  In addition, when performing skew detection processing, it is necessary to execute fence movement control in order of the side fence 1 and the end fence 2, so that it takes extra time for fence movement control. If the paper is placed carefully, there may be a user who does not need such skew detection processing and correction processing. Such a user is the side fence 1. Since the movement control of the end fence 2 can be performed at the same time, the time for the fence movement control can be shortened. Therefore, the execution / non-execution of these controls may be stored in a non-volatile storage medium (for example, NVRAM) of the image forming apparatus so that this value can be changed. In this way, it is possible to cope with the situation.

  In this way, according to the second embodiment, in addition to automatically moving the fence in the tray and automatically determining the paper size, an abnormality of a skew phenomenon in which an image is printed obliquely with respect to the paper is detected. And can be corrected. For this reason, even when the user places the paper at an angle when the paper is supplied to the tray, it is possible to print an image on the printing paper without being inclined, that is, to prevent a skew phenomenon. Become.

  The processing operation in the above-described embodiment can be executed by hardware, software, or a combined configuration of both.

  When processing by software is executed, the program is loaded from a ROM (Read Only Memory) storing a program recording a processing sequence to a memory (RAM) in a computer incorporated in dedicated hardware. The program can be read and executed, or the program can be installed and executed on a general-purpose computer capable of executing various processes.

  For example, the program can be recorded in advance on a hard disk or ROM as a recording medium. Alternatively, the program is stored on a removable recording medium such as a magnetic disk such as a floppy (registered trademark) disk, an optical disk such as a CD (Compact Disc) or DVD (Digital Versatile Disc), or a magneto-optical disk such as an MO (Magneto Optical) disk. It is possible to store (record) temporarily or permanently.

  Such a removable recording medium can be provided as so-called package software.

  The program is installed on the computer from the above-described removable recording medium, transferred wirelessly from the download site to the computer, or transferred to the computer via a network such as a LAN (Local Area Network) or the Internet. On the other hand, the computer can receive the transferred program and install it on a recording medium such as a built-in hard disk.

  In addition to being executed in time series in accordance with the processing operations described in the above embodiment, the processing capability of the apparatus that executes the processing, or a configuration to execute in parallel or individually as necessary Is also possible.

  In addition, the system described in the above embodiment can be configured to have a logical set configuration of a plurality of devices or to mix the functions of each device.

  The present invention has been described above by the preferred embodiments of the present invention. While the invention has been described with reference to specific embodiments thereof, various modifications and changes can be made to these embodiments without departing from the broader spirit and scope of the invention as defined in the claims. is there.

  The image forming apparatus according to the present invention includes a rotation unit that rotates the fence when it contacts the paper, a rotation amount detection unit that detects a rotation amount of the fence, and the rotation amount detection unit that detects the rotation amount detection unit. A skew amount measuring means for measuring the skew amount based on the amount of rotation of the fence may be further included.

  In the image forming apparatus according to the present invention, when the skew amount measured by the paper rotation means for rotating the paper and the skew amount measurement means is larger than a predetermined value, the paper rotation means rotates the paper. And a skew correction means for automatically correcting the skew.

  The image forming apparatus according to the present invention further includes a printability determination unit that determines whether the size in the main scanning direction and the size in the sub-scanning direction of the paper measured by the size measuring unit are printable sizes. Furthermore, you may make it have.

  The image forming apparatus according to the present invention may further include a unit that automatically moves the fence to a predetermined position when the opening / closing detection unit detects that the tray is opened.

1 Side fence 2 End fence

Japanese Patent Laid-Open No. 08-119467 Japanese Patent No. 423030

Claims (5)

Open / close detecting means for detecting opening / closing of the tray;
Paper presence / absence detecting means for detecting the presence / absence of paper in the tray;
End face detecting means for detecting an end face of the paper;
A fence that aligns the edges of the paper;
When the open / close detection means detects that the tray is closed, and when the paper presence / absence detection means detects that the paper is present, the fence is moved, and the end face detection means detects the end face of the paper. Position determining means for automatically determining the position of the fence when
An image forming apparatus comprising: a size measuring unit that automatically measures the size in the main scanning direction and the size in the sub scanning direction of the sheet based on the amount of movement of the fence by the position determining unit. Rotating means for rotating the fence when in contact with the paper;
A rotation amount detecting means for detecting a rotation amount of the fence;
The image forming apparatus according to claim 1, further comprising: a skew amount measuring unit that measures a skew amount based on the rotation amount of the fence detected by the rotation amount detecting unit. Paper rotating means for rotating the paper;
The apparatus further comprises skew correction means for automatically correcting the skew by rotating the paper by the paper rotation means when the skew amount measured by the skew amount measurement means is larger than a predetermined value. Item 3. The image forming apparatus according to Item 2.   The printability determination means for determining whether or not the size in the main scanning direction and the size in the sub-scanning direction of the paper measured by the size measuring means are both printable sizes. 4. The image forming apparatus according to any one of items 1 to 3.   5. The apparatus according to claim 1, further comprising: a unit that automatically moves the fence to a predetermined position when the opening / closing detection unit detects that the tray is opened. Image forming apparatus.

Images