JP2009186798A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of detecting the direction of an envelope subjected to image formation, thereby automatically setting the direction of the image formation to be matched with the direction of the envelope. <P>SOLUTION: In the image forming apparatus, change of thickness in a paper conveying direction of the envelope subjected to image formation about image data is detected (S3) at least before an electrostatic latent image based on the image data is formed on a photoreceptor (before S8), and if the change of the thickness is detected (No side in S5), the direction of the envelope is detected according to the state of the change of thickness (S10 to S12). Then, the direction of image formation on the envelope is set to be fit to the direction of the envelope detected in the steps S10 to S12 (S13). Thus, the direction of the envelope is automatically fit to the direction of image formation and misprint is prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer that forms an image on paper based on input image data, and more particularly to a technique for preventing misprinting when address printing is performed on an envelope. It is.

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, it is possible to set an envelope on a manual feed tray and perform image formation such as address printing on the envelope.
At this time, since the envelope is an overlap of the two sheets of paper on the front and back, when the sheet is conveyed while being pressed by two rollers in the fixing device, the two sheets of paper on the front and back may be displaced to cause wrinkles. . Therefore, for example, Patent Document 1 discloses a technique for preventing the envelope from being wrinkled by reducing the pressure of the pressure roller in the fixing device when it is detected that the sheet is an envelope. ing.
JP 2007-102119 A

However, in Patent Document 1, in order to adjust the pressure of the pressure roller, it is merely detected whether the paper used for image formation is plain paper or an envelope, and the paper is an envelope. In some cases, the orientation of the envelope could not be determined.
On the other hand, when address printing is performed on an envelope with the image forming apparatus, if the envelope orientation is set in reverse with respect to the address orientation, a misprint occurs in which the address is printed upside down. In particular, since the correspondence relationship between the printing direction and the paper direction may differ depending on the image forming apparatus, the correspondence relationship may differ from the user's recognition.
Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to detect the orientation of an envelope used for image formation and automatically adjust the orientation of image formation in accordance with the orientation of the envelope. It is an object of the present invention to provide an image forming apparatus that can be set as follows.

In order to achieve the above object, the present invention is applied to an image forming apparatus that forms an image on a sheet based on input image data, and at least an electrostatic latent image based on the image data is a photosensitive member. A thickness change detecting means for detecting a change in thickness in the paper transport direction in an envelope provided for image formation of the image data, and a change in thickness detected by the thickness change detecting means In addition, an envelope direction detecting means for detecting the direction of the envelope according to the change of the thickness, and an image forming direction with respect to the envelope is set in accordance with the direction of the envelope detected by the envelope direction detecting means. The image forming apparatus includes a printing direction setting unit.
According to the present invention, even if the orientation of image formation does not match the orientation of the envelope, the orientation of image formation is automatically set to match the orientation of the envelope. Can be prevented. Thereby, for example, it is possible to save the user's trouble such as performing test printing for confirming the correspondence between the image forming direction and the envelope direction in the image forming apparatus.
Here, it is conceivable that the change in the thickness is, for example, the thinnest of the leading edge and the trailing edge of the envelope in the sheet conveyance direction. In general, a binding margin for closing the opening is provided at the upper end portion of the envelope, and the binding margin is a sheet of paper, and the binding margin portion is the smallest thickness portion in the envelope. Therefore, the direction of the envelope in the paper conveyance direction can be specified by specifying in which direction the binding margin is directed.
Further, the change in thickness may be a change pattern in thickness from the front end to the rear end in the paper transport direction of the envelope. In general, the thickness of the envelope is smaller in the order of the binding margin at the upper end (one sheet of paper), the main body (two sheets of paper), and the closing portion at the lower end (three sheets of paper). Therefore, the direction of the envelope can be specified by the change pattern. For example, if it is detected that the envelope thickness changes greatly in two stages from the front end to the rear end in the paper conveyance direction of the envelope, the direction of the envelope is reversed (the paper conveyance direction is the lower end of the envelope). I understand that.

According to the present invention, even if the orientation of image formation does not match the orientation of the envelope, the orientation of image formation is automatically set to match the orientation of the envelope. Can be prevented. Thereby, for example, it is possible to save the user's trouble such as performing test printing for confirming the correspondence between the image forming direction and the envelope direction in the image forming apparatus.
Specifically, the direction of the envelope may be specified in accordance with the thinnest of the leading edge and the trailing edge of the envelope in the paper conveyance direction and the change pattern of the thickness from the leading edge to the trailing edge in the paper conveyance direction of the envelope. Is possible.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
Here, FIG. 1 is a schematic diagram showing a schematic configuration of an image forming apparatus X according to an embodiment of the present invention, FIG. 2 is a diagram for explaining a change in sheet thickness, and FIG. 3 is an embodiment of the present invention. FIG. 4 is a flowchart for explaining an example of a procedure of image forming processing executed in the image forming apparatus X according to FIG. 4, and FIG.
First, the schematic configuration of the image forming apparatus X according to the embodiment of the present invention will be described with reference to FIG. The image forming apparatus X is a printer apparatus, a copier, a facsimile apparatus, or a complex machine of these that forms an image on a sheet based on input image data. Further, the image forming apparatus X may be either a monochrome compatible or a color compatible image forming apparatus.
As shown in FIG. 1, the image forming apparatus X includes an operation display unit 1 for performing various operation inputs and various displays by a user, and a document or document table automatically conveyed by an ADF (automatic conveyance device). An image is formed on a sheet based on the image reading unit 2 that reads an image from a set original and the image data input from the image reading unit 2 or the image data input from an external information processing apparatus (such as a personal computer). An image forming unit 3; a thickness detection sensor 4 for detecting a thickness of a sheet provided to the image forming unit 3; a manual feed tray 5 on which a sheet provided to the image forming unit 3 is placed; The paper feeding cassettes 6 and 7 that store papers to be provided to the unit 3 and a control unit 8 that comprehensively controls the image forming apparatus X are schematically configured.
The control unit 8 includes a control device such as a CPU, a RAM, and a ROM, for example. The CPU develops a control program stored in the ROM and executes the control program, which will be described later. Various control processes such as (refer to the flowchart of FIG. 2) are executed.

The image forming unit 3 exposes the surface of the charged photosensitive drum 31 by writing the electrostatic latent image by exposing the surface of the photosensitive drum 31 to the photosensitive drum 31 that carries the toner image, the charging device 32 that charges the surface of the photosensitive drum 31. An exposure device 33, a developing device 34 for developing the electrostatic latent image on the photosensitive drum 31 with toner, a transfer device 35 for transferring the toner image on the rotating photosensitive drum 31 to a sheet, and a residual toner on the photosensitive drum 31 A cleaning device 36 that removes the image, a fixing device 37 that fixes the toner image transferred onto the sheet to the sheet, and the like are provided.
Here, the sheet on which image formation is performed in the image forming unit 3 is conveyed to the image forming unit 3 from the manual feed tray 5 and the sheet feeding cassettes 6 and 7 through the sheet conveying path 50. On the paper transport path 50, pick-up rollers and transport rollers for transporting paper are provided at various locations.
A registration roller 51 for matching the timing of image writing by the image forming unit 3 with the leading edge of the paper on the paper conveyance path 50, and detection of the presence or absence of paper in the vicinity of the registration roller 51 are not shown. The registration sensor is provided.

The thickness detection sensor 4 is disposed at a predetermined position on the paper transport path 50 in order to detect a change in the thickness of the paper transported on the paper transport path 50. For example, the thickness detection sensor 4 is arranged so that the trailing edge of the paper passes through the thickness detection sensor 4 until the paper reaches the registration roller 51 on the paper conveyance path 50.
Here, FIG. 2A is a diagram of the thickness detection sensor 4 as viewed in the paper transport direction along the paper transport path 50. As shown in FIG. 2A, the thickness detection sensor 4 includes a light emitting unit 41 that emits light toward the paper P conveyed on the paper conveyance path 50, and a paper P irradiated from the light emitting unit. An optical system that receives the transmitted light, and inputs a voltage having a magnitude corresponding to the intensity of the light detected by the light receiving section 42 (a voltage that increases as the intensity increases) to the control section 8. Sensor. In this case, the control unit 8 can detect a change in the thickness of the sheet P conveyed to the sheet conveyance path 50 based on the magnitude of the voltage input from the light receiving unit 42.
Specifically, when the plain paper P1 shown in FIG. 2B is transported through the paper transport path 50, the thickness detection sensor 4 has a constant thickness from the upper end to the lower end of the plain paper P1. Is detected.
On the other hand, the envelope P2 shown in FIG. 2 (c) has an upper end portion 101 made of one sheet as a binding margin for closing the opening of the envelope P2, and a main body portion 102 in which the two sheets overlap. And the lower end 103 on which three sheets of paper are overlapped by closing the opening at the lower end. Therefore, when the envelope P2 is conveyed along the paper conveyance path 50, the thickness detection sensor 4 detects a change in thickness from the upper end to the lower end of the envelope P2. Specifically, the thickness detection sensor 4 detects that (the thickness of the upper end portion 101 <the thickness of the main body portion 102 <the thickness of the lower end portion 103).
The thickness detection sensor 4 is not limited to an optical type, and may be another sensor that can detect a change in the thickness of the paper, such as a sensor using ultrasonic waves or a contact type displacement sensor. Furthermore, the thickness detection sensor 4 can also be used as a sensor for detecting a paper jam on the paper transport path 50, for example.

By the way, when the image forming apparatus X forms an image such as an address on the envelope P2, the user sets the envelope P2 on the manual feed tray 5 in an arbitrary direction. The user can perform image formation on the envelope P2 set on the manual feed tray 5 by setting the use of the manual feed tray 5 in the print setting.
However, if the orientation of the envelope P2 set on the manual feed tray 5 at this time does not match the orientation of image formation such as the address printed on the envelope P2, the image formation such as the address is reversed on the envelope P2. Will be given.
Therefore, in the image forming apparatus X, the control unit 8 automatically performs the image forming process according to the procedure described later (see the flowchart in FIG. 3), thereby automatically changing the image forming direction such as the address according to the direction of the envelope P2. Mis-printing is prevented by making adjustments.

An example of the procedure of the image forming process executed by the control unit 8 in the image forming apparatus X will be described below with reference to the flowchart of FIG. In the figure, S1, S2,... Represent processing procedure (step) numbers.
First, in step S1, input of image data is awaited by the control unit 8 (No side of S1), and when image data is input from the image reading unit 2 or an external device (Yes side of S1). , The process proceeds to step S2. The image data also includes information about print settings such as whether the manual feed tray 5 or the paper feed cassettes 6 and 7 are used to supply paper to the image forming unit 3.
In the following, the envelope P2 (see FIG. 2C) is set in advance on the manual feed tray 5 by the user, print settings are made to execute image formation using the manual feed tray 5, and image data is input. A case will be described as a specific example.

In step S2, various paper transport rollers provided on the paper transport path 50 are driven by the control unit 8, so that the envelope P2 set on the manual feed tray 5 is transferred to the image forming unit 3. The conveyance is started.
At this time, in step S <b> 3, the control unit 8 controls the thickness detection sensor 4 to detect a change in thickness in the sheet conveyance direction in the envelope P <b> 2 conveyed through the sheet conveyance path 50. The detection process is executed before image formation is started in step S8, which will be described later, that is, at least before an electrostatic latent image based on image data is formed on the photosensitive drum 31 by the exposure device 33. . Here, the control unit 8 and the thickness detection sensor 4 when executing such detection processing correspond to thickness change detection means. The detection process continues until it is detected in the next step S4 that the rear end of the envelope P2 has passed through the thickness detection sensor 4 (No side of S4). In step S4, the control unit 8 detects whether or not the rear end of the envelope P2 only passes based on the detection result by the thickness detection sensor 4. In step S4, it may be detected that the envelope P2 has passed through the thickness detection sensor 4 when the envelope P2 reaches the registration roller 51.

Here, the change in the thickness of the envelope P2 detected by the thickness detection sensor 4 in the step S3 will be described with reference to FIG.
First, as shown in FIG. 4A, when the upper end portion 101 of the envelope P2 faces the front end in the sheet conveying direction, the envelope P2 detects the thickness in the order of the upper end portion 101, the main body portion 102, and the lower end portion 103. The sensor 4 is passed. At this time, as shown in FIG. 4B, the output voltage V from the thickness detection sensor 4 gradually decreases at the positions of the upper end 101, the main body 102, and the lower end 103, and the thicknesses increase in that order. It is small. That is, it can be seen from the detection result of the thickness detection sensor 4 that the front end of the envelope P2 in the paper transport direction is the upper end portion 101 having the smallest thickness.
On the other hand, as shown in FIG. 4C, when the lower end portion 103 of the envelope P2 faces the front end in the sheet conveying direction, the envelope P2 detects the thickness in the order of the lower end portion 103, the main body portion 102, and the upper end portion 101. The sensor 4 is passed. At this time, as shown in FIG. 4D, the output voltage V from the thickness detection sensor 4 increases stepwise at the positions of the lower end portion 103, the main body portion 102, and the upper end portion 101, and the thicknesses increase in that order. It is big. That is, it can be seen from the detection result of the thickness detection sensor 4 that the rear end of the envelope P2 in the sheet conveying direction is the upper end 101 having the smallest thickness.

Next, when the control unit 8 detects that the paper on the paper transport path 50 has passed through the thickness detection sensor 4 (Yes side of S4), the control unit 8 shifts the processing to step S5.
In step S5, the control unit 8 determines whether or not the thickness detected by the thickness detection sensor 4 is constant. If the thickness is constant (Yes in S5), the sheet is normal. It is determined that the paper is P1 (S6), and if the thickness is not constant (No side of S5), it is determined that the paper is envelope P2 (S9). As described above, the control unit 8 can detect the paper type of the plain paper P1 or the envelope P2 in accordance with the detection result of the thickness detection sensor 4.
Here, since envelope P2 is conveyed, it is detected by thickness detection sensor 4 that there is a change in thickness (No side of S5), and the process proceeds to step S9.
When the paper used for image formation is plain paper P1 (S6), the control unit 8 keeps the pressure of the paper in the fixing device 37 set to the normal pressure in the subsequent step S7. In step S8, image formation based on the image data is started.

If it is determined in step S9 that the sheet is the envelope P2, the control unit 8 determines in step S10 the sheet conveyance direction in the envelope P2 based on the change in the thickness of the envelope P2 detected by the thickness detection sensor 4. Determine which is the thinnest at the leading or trailing edge. Here, it is determined which of the front end and the rear end of the envelope P2 is the thinnest, but it may be determined which of the front end and the rear end of the envelope P2 is relatively thin. . In addition, for example, a threshold value of a voltage for detecting that the number of sheets is one is set in advance, and the light receiving unit 42 of the thickness detection sensor 4 determines which of the front and rear ends of the envelope P2 in the sheet conveyance direction. It may be determined whether one of the leading edge and the trailing edge of the envelope P2 in the sheet conveyance direction is one sheet, depending on whether a voltage equal to or higher than the threshold is output.
Here, when it is determined that the front end of the envelope P2 in the paper transport direction is the thinnest, the control unit 8 determines that the envelope P2 is transported with the upper end 101 being directed to the front end in the paper transport direction. Judgment is made (S11).
On the other hand, when it is determined that the rear end of the envelope P2 in the sheet conveyance direction is the thinnest, the control unit 8 determines that the envelope P2 is conveyed with the lower end 103 facing the front end in the sheet conveyance direction. Judgment is made (S12).
As described above, the control unit 8 responds to the aspect of the change in the thickness of the envelope P2 detected by the thickness detection sensor 4, specifically, which of the front end and the rear end in the sheet conveyance direction of the envelope P2 is the thinnest. Then, the direction of the envelope P2 is detected. The said control part 8 when performing the detection process which concerns here corresponds to an envelope direction detection means.

Next, in step S13, the control unit 8 automatically sets the image forming direction for the image data so as to match the direction of the envelope P2 specified in either step S11 or S12. Here, the control unit 8 when executing the setting process corresponds to a printing direction setting unit.
Specifically, when it is determined in step S12 that the lower end portion 103 of the envelope P2 is directed to the front end in the sheet conveying direction (reverse direction), the image forming direction is adjusted in accordance with the direction. Change so that is reversed. Note that the change in the image forming direction is to start the transfer order of the image data by the control unit 8 from the reverse, or to cause the exposure device 33 to form an electrostatic latent image in the reverse direction. What is necessary is just to implement | achieve by another known method.

Thereafter, the controller 8 sets the pressure of the sheet by the fixing roller in the fixing device 37 to a pressure at the time of the envelope that is weaker than normal (S14). In this way, by adjusting the pressure according to the paper type, it is possible to prevent the envelope P2 from being wrinkled in the fixing device 37.
Then, the control unit 8 executes image formation on the envelope P2 for the image data in the image formation direction set in step S13 (S8). Specifically, in step S8, image data is transferred to the exposure device 33 by the controller 8, and formation of an electrostatic latent image on the photosensitive drum 31 by the exposure device 33 is started. Thereafter, the electrostatic latent image formed on the photosensitive drum 31 is developed and transferred and fixed on the envelope P2.
As described above, in the image forming apparatus X, at least before the electrostatic latent image based on the image data from the exposure device 33 is formed on the photosensitive drum 31, the envelope P2 used for image formation is formed. By detecting the orientation and automatically setting the orientation of image formation in accordance with the orientation of the envelope P2, it is possible to prevent misprinting such that an image formation such as an address is applied to the envelope P2 in the reverse direction. .

By the way, in the present embodiment, after detecting the total thickness of the sheet conveyed on the sheet conveyance path 50, it is determined whether or not the sheet is the envelope P2 and the direction of the envelope P2. Was described as an example.
On the other hand, for example, if a change in thickness is detected while detecting the thickness of the sheet by the thickness detection sensor 4 in step S3, it is determined that the sheet is the envelope P2 at that time and the thickness is detected. It is conceivable that the detection by the detection sensor 4 is interrupted, and further, the orientation of the envelope P2 is determined according to the change mode.
Specifically, when a portion having a thickness larger than the front end in the paper transport direction is detected in the envelope P2, it is determined that the front end in the paper transport direction is the upper end portion 101 of the envelope P2, and the thickness is larger than that of the front end. If a small portion is detected, it may be determined that the leading end in the paper transport direction is the lower end portion 103 of the envelope P2.
By processing in this way, the detection time by the thickness detection sensor 4 is shortened, the waiting time until the start of formation of an electrostatic latent image on the photosensitive drum 31 by the exposure device 33 is shortened, and the thickness detection sensor 4 In addition, the path between the registration rollers 51 can be shortened, and the printing speed can be increased.

In the above-described embodiment, the case where the direction of the envelope P2 is detected based on which of the front end and the rear end of the envelope P2 in the sheet conveyance direction is the thinnest has been described as an example, but the present invention is not limited to this. In the present embodiment, another method for detecting the orientation of the envelope P2 will be described.
As shown in FIG. 4B, when the leading end of the envelope P2 in the paper transport direction is the upper end portion 101, the thickness of the envelope P2 detected by the thickness detection sensor 4 from the front end to the rear end in the paper transport direction. Change pattern (or voltage change pattern) and a thickness change pattern (or voltage change pattern) detected when the leading end of the envelope P2 in the paper conveyance direction is the lower end portion 103 as shown in FIG. ) Is previously stored in the ROM of the control unit 8 or the like.
As a result, the control unit 8 displays the thickness change pattern (an example of a change mode) from the leading edge to the trailing edge of the envelope P2 detected by the thickness detection sensor 4 in the step S10. It is possible to detect the orientation of the envelope P2 in the paper conveyance direction by determining which of the change patterns in 4 (b) and FIG. 4 (d) is approximate. Here, the control unit 8 when executing the detection process is also an example of the envelope direction detection means.
In this case, since the orientation of the envelope P2 can be determined by the change in the overall thickness of the envelope P2, even when a punch hole or a cutout is formed in a part of the envelope P2. , Misdetection of the orientation of the envelope P2 can be prevented.

1 is a schematic diagram showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention. The figure for demonstrating the change of the thickness of a paper. 6 is a flowchart for explaining an example of a procedure of image forming processing executed in the image forming apparatus according to the embodiment of the present invention. The figure for demonstrating the relationship between the direction of an envelope, and the aspect of a change of thickness.

Explanation of symbols

1: Operation display unit 2: Image reading unit 3: Image forming unit 4: Thickness detection sensor 41: Light emitting unit 42: Light receiving unit 5: Manual feed tray 6, 7: Paper feed cassette 8: Control units S1, S2,. Procedure (Step) Number X: Image Forming Apparatus

Claims (3)

An image forming apparatus that forms an image on a sheet based on input image data,
A thickness change detecting means for detecting a change in thickness in the paper transport direction in an envelope provided for image formation of the image data before an electrostatic latent image based on at least the image data is formed on the photoreceptor;
An envelope direction detecting means for detecting the direction of the envelope according to the thickness change mode when a change in thickness is detected by the thickness change detecting means;
A printing direction setting means for setting a direction of image formation with respect to the envelope in accordance with the direction of the envelope detected by the envelope direction detecting means;
An image forming apparatus comprising:   2. The image forming apparatus according to claim 1, wherein the change in the thickness is the thinnest of a leading edge and a trailing edge of the envelope in a sheet conveyance direction.   The image forming apparatus according to claim 1, wherein the change in thickness is a change pattern in thickness ranging from a leading edge to a trailing edge of the envelope in a sheet conveyance direction.

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