JP2007176695A - Image forming device and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the occurrence of a jam resulting from unconformity of a curve of carrying passages and flexibility of recording paper, by switching the carrying passages by taking into consideration a physical parameter on the flexibility of the recording paper. <P>SOLUTION: This image forming device has a plurality of carrying passages for carrying the recording paper and a plurality of paper delivery parts respectively arranged on the tail end of the carrying passages. The image forming device also switches the carrying passages in response to a detected parameter by detecting the physical parameter on the flexibility of the recording paper. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for conveying recording paper in an image forming apparatus.

  2. Description of the Related Art Conventionally, there has been proposed an image forming apparatus in which an image forming apparatus having a plurality of paper discharge trays and a paper discharge option apparatus having a plurality of paper discharge bins can be mounted. Such a plurality of paper discharge trays and paper discharge bins are convenient, for example, when sorting recording sheets on which images are recorded.

  However, there are cases in which a plurality of paper discharge bins cannot receive a relatively large size recording paper. In this case, there is a drawback that the print job stops when the user designates an inappropriate paper discharge bin. In the case of a printer connected to a network, this becomes a factor that extremely reduces the operation rate.

As a countermeasure against this, there has been proposed a method of switching a paper discharge destination to a paper discharge tray capable of paper discharge when a recording paper having a size that cannot be discharged to the paper discharge tray designated by the user is detected ( Patent Document 1).
JP-A-9-188455

  Incidentally, a conveyance path for guiding recording paper to a plurality of paper discharge trays and paper discharge bins generally includes a relatively straight portion and a curved portion having a certain curvature.

  On the other hand, the types of recording paper used in image forming apparatuses are increasing year by year. Among the recording sheets, there are recording sheets with relatively high flexibility and recording sheets with relatively low flexibility.

  In particular, when the user uses an inappropriately thick recording paper, the recording paper may be jammed at the curved portion of the conveyance path. In the above-described prior art, the paper discharge tray is switched according to the size of the recording paper, but the size is not necessarily related to flexibility. For this reason, it has not been possible to reduce the jam that occurs due to insufficient flexibility of the recording paper.

  Accordingly, the present invention has been made to solve such a problem, and an object thereof is to reduce a jam that occurs due to a lack of flexibility of recording paper.

  The present invention can be suitably applied to an image forming apparatus having a plurality of conveyance paths for conveying recording paper and a plurality of paper discharge units provided at the end of the conveyance path. The image forming apparatus detects a physical parameter related to the flexibility of the recording paper, and switches the conveyance path according to the detected parameter.

  According to the present invention, the occurrence of a jam due to the flexibility of the recording paper can be reduced by switching the conveyance path in consideration of the parameter relating to the flexibility of the recording paper.

  An embodiment of the present invention is shown below. Of course, the individual embodiments described below will be helpful in understanding various concepts such as the superordinate concept, intermediate concept and subordinate concept of the present invention. Further, the technical scope of the present invention is determined by the scope of the claims, and is not limited by the following individual embodiments.

[First Embodiment]
FIG. 1 is a diagram illustrating a schematic configuration of an exemplary image forming apparatus according to the embodiment. The image forming apparatus 100 is an electrophotographic printer. However, the present invention does not depend on the image forming method. Therefore, the present invention can be suitably applied to an image forming apparatus that employs another method such as an ink jet method.

  The image forming unit 110 is a so-called electrophotographic image forming engine. The recording paper stored in the recording paper cassette 113 and the recording paper fed from the hand tray 114 are conveyed to the image forming unit 110 to form an image.

  In this embodiment, a paper thickness sensor 116 is employed as a detection unit for detecting a physical parameter related to the flexibility of the recording paper. The paper thickness sensor 116 is a leading sensor that measures the thickness of the recording paper. In place of the paper thickness sensor 116 or together with the paper thickness sensor 166, a sensor capable of detecting the weight, stiffness, density, etc. of the recording paper may be employed. Here, “koshi” is a term representing the ease of bending of the recording paper.

  The paper detection sensor 121 is a sensor for detecting the recording paper on which an image is formed and conveyed. The paper discharge roller 122 is a roller that conveys the recording paper on which the image is formed to the flapper 123.

  The flapper 123 is a mechanism for switching the conveyance path according to the detected parameter. For example, the types of paper discharge include face-up paper discharge and face-down paper discharge. Face-up discharge refers to discharging recording sheets one by one with the image forming surface facing upward. On the other hand, face-down paper discharge means that the recording paper is discharged one by one in the order of the pages with the image forming surface facing down.

  In the case of face-up paper discharge, the flapper 123 is controlled by the control unit 150 and switched so as to guide the recording paper to the transport path 130. In this case, the recording paper is discharged to the face-up discharge tray 125 by the discharge roller 124. On the other hand, in the case of face-down paper discharge, the flapper 123 is controlled by the control unit 150 and switched to guide the recording paper to the transport path 131. In this case, the recording paper is transported by the transport rollers 126 and 127 and discharged to the face-down paper discharge tray 128.

  FIG. 2 is a block diagram illustrating a control unit according to the embodiment. The image forming controller 201 expands image data (such as PDL data) received from a host computer or the like into bitmap data. Note that the image forming controller 201 communicates with the engine control unit 202 to recognize the state inside the image forming apparatus and to send a command for switching the operation mode of the image forming apparatus.

  The engine control unit 202 controls each unit in the image forming apparatus based on a command transmitted from the image forming controller 201. The engine control unit 202 receives a detection signal from the paper thickness sensor 116 and a detection signal from the paper detection sensor 121. The engine control unit 202 uses the detected signal for transport control and transport path switching control.

  The conveyance control unit 203 drives a paper conveyance system inside the image forming apparatus based on an instruction from the engine control unit 202. The flapper drive motor 204 is a motor for switching the flapper 123 based on an instruction from the conveyance control unit 203.

  FIG. 3 is a diagram illustrating an example of a paper thickness sensor. The paper thickness sensor is an optical reflective displacement sensor, but the paper thickness sensor of the present invention is not limited to the optical reflective displacement sensor.

  The paper thickness sensor 116 irradiates a detection medium (eg, recording paper) with light from a light emitting element (eg, LED) 301 and detects reflected light from the detection medium with a lens 302 and a position detection element (PSD) 303. is doing. The reflected light from the detection medium is collected on the PSD 303 by the lens 302.

  For example, when the thickness of the detection medium is x, the reflected light is collected at point B on the PSD 303 (solid line). On the other hand, when there is no detection medium, the reflected light is collected at point A on the PSD 303 (dotted line). As described above, the position of the center of gravity of the collected reflected light changes according to the thickness x of the detection medium. Therefore, the thickness x of the detection medium can be measured by processing the output signal from the PSD 303.

  FIG. 4 is a diagram illustrating the relationship between the output signal from the position detection element and its position information. Output currents from the PSD 303 are I1 and I2. Let L be the total length of the PSD 303. If the distance from the center of the PSD 303 to the center of gravity of the reflected light is y, the following equation is established.

(I1-I2) / (I1 + I2) = 2y / L
FIG. 5 is a circuit diagram illustrating a portion of an exemplary paper thickness sensor. That is, the above equation is expressed by this circuit diagram. The output currents I1 and I2 are input to the subtraction circuit 503 and the addition circuit 504 via current-voltage conversion elements 501 and 502, respectively. The output of the subtraction circuit 503 and the output of the addition circuit 504 are input to the division circuit 505. Then, position information is output from the division circuit 505. Since the output position information is a voltage value, it is converted into a digital value by the A / D converter in the engine control unit 202. The engine control unit 202 multiplies the digital value by a predetermined coefficient to obtain final position information.

  FIG. 6 is a flowchart illustrating the paper conveyance control according to the embodiment. In step 601, the engine control unit 202 stands by until a print command is issued from the image forming controller 201. When the print command is received, the process proceeds to step 602.

  In step 602, the engine control unit 202 determines whether or not the face-down discharge tray 128 is designated as a discharge destination. As shown in FIG. 1, a curved section exists in a part of the conveyance path to the paper discharge tray 128. Therefore, this determination processing determines whether or not a paper discharge tray (or paper discharge bin) provided at the end of the conveyance path having a curved section where paper jam can occur is designated as a paper discharge destination. It is synonymous with. Of course, the conveyance path 131 having such a curved section is a conveyance path that requires flexibility for the recording paper. That is, the conveyance path 131 is a conveyance path that can convey a recording sheet having a predetermined flexibility or more. If a recording sheet that does not have a predetermined flexibility (less flexible) passes through such a conveyance path 131, a jam is likely to occur. The value of the predetermined flexibility or more is determined by the physical characteristics (friction coefficient, curvature, etc.) of the conveyance path.

  If the paper discharge tray 128 is designated, the process proceeds to step 603. On the other hand, if the paper discharge tray 128 is not designated, the engine control unit 202 ends the processing according to this flowchart. That is, if the paper discharge tray 125 is designated as the paper discharge destination, the switching of the flapper 123 is not executed. This is because the conveyance path 130 to the paper discharge tray 125 is almost straight, so that flexibility is not required for the recording paper. In other words, the conveyance path 130 is a conveyance path that can convey recording paper that does not have a predetermined flexibility or more (insufficient flexibility). Therefore, the conveyance path 130 can be said to be a conveyance path that is relatively less likely to cause jams than the conveyance path 131.

  In step 603, the engine control unit 202 starts feeding recording paper from the designated paper feed cassette 113 or manual feed tray 114. In step 604, the engine control unit 202 captures the detection result (recording paper thickness information) from the paper thickness sensor 116.

  In step 605, the engine control unit 202 determines whether the thickness of the recording paper exceeds a predetermined threshold value. As the threshold value, a value of the thickness of the recording paper that makes it difficult or substantially impossible to convey to the paper discharge tray 128 is adopted. Therefore, this threshold value depends on the curvature of the curved portion of the conveyance path 131, the friction coefficient, and the like. It should be noted that the threshold value is desirably determined experimentally for each image forming apparatus. If the detected thickness does not exceed the threshold value, the processing according to this flowchart is terminated without switching the flapper 123. On the other hand, if the detected thickness exceeds the threshold value, the process proceeds to step 606.

  In step 606, the engine control unit 202 sends a flapper 123 switching command to the transport control unit 203 in order to switch the paper discharge destination to the paper discharge tray 125. The transport control unit 202 drives the flapper drive motor 204 in response to this command. As a result, the conveyance path of the recording paper is switched to the conveyance path 130 provided with the discharge tray 125 at the end.

  As described above, according to the present embodiment, the flexibility of the recording paper is insufficient by switching the conveyance path according to the physical parameter (for example, the thickness of the recording paper) regarding the flexibility of the recording paper. The occurrence of jams associated with being present can be reduced or suppressed.

  That is, a paper discharge tray 128 provided at the end of the conveyance path 131 that requires relatively flexibility with respect to the recording paper, and a paper discharge tray provided at the end of the conveyance path 130 that does not require relatively flexibility. The present invention will be preferably applied when 125 is present. That is, the engine control unit 202 switches the conveyance path so that the recording sheet is discharged to the discharge tray 125 when the parameter (for example, thickness) regarding the recording sheet to be discharged exceeds a threshold value. As a result, recording paper that is likely to jam in the transport path 131 of the paper discharge tray 128 can be discharged to the paper discharge tray 125. Therefore, occurrence of jam can be preferably suppressed.

  In addition, when the parameter exceeds the threshold value, the engine control unit 202 sets a conveyance path so that the recording sheet is discharged to the discharge tray 125 even if it is designated in advance to discharge the recording sheet to the discharge tray 128. Switch. Of course, if it is originally designated to discharge the recording paper to the paper discharge tray 128, switching of the transport path is not necessary. As described above, there is an advantage that the conveyance path only needs to be switched when jamming is likely to occur.

  In the above-described embodiment, the thickness of the recording paper is used as an example of the parameter. However, the present invention is not limited to this. For example, weight (basis weight), stiffness, density, or the like may be adopted as a parameter regarding flexibility. The basis weight indicates the weight per certain area. In this case, it goes without saying that a separate sensor for detecting the weight, stiffness, density, etc. is required.

[Second Embodiment]
In the first embodiment, the recording paper conveyance control in the image forming apparatus main body has been described. Therefore, in the second embodiment, conveyance control in a state where the option device is mounted on the image forming apparatus 100 will be described.

  FIG. 7 is a diagram illustrating a schematic configuration of an image forming apparatus according to the second embodiment. In addition, description is simplified by attaching | subjecting the same referential mark to the already demonstrated location. The image forming apparatus 100 is equipped with a paper discharge option device 700.

  When paper is discharged to the paper discharge option device 700, the flapper 123 is switched to the upper side (the state of the broken line in FIG. 7). Accordingly, the recording paper is guided into the paper discharge option device 700 by the paper discharge roller 124.

  When the paper detection sensor 121 detects the leading edge of the recording paper, the engine control unit 202 starts driving the reverse flapper 730. When the recording paper is carried into the paper discharge option device 700, the engine control unit 202 starts rotating the reversing roller 731 and further draws the recording paper into the paper discharge option device 700.

  When the trailing edge of the recording paper passes through the reverse sensor 732, the engine control unit 202 reversely rotates the reverse roller 731 and switches the reverse flapper 730 to the position indicated by the solid line in FIG. To drive.

  The reversed recording paper is conveyed above the apparatus. The engine control unit 202 appropriately switches the flappers 739 to 741 corresponding to the paper discharge trays 736 to 738 to discharge the conveyed recording paper to a desired paper discharge tray. The paper discharge tray 742 is a strong paper discharge tray for recording paper.

  FIG. 8 is a block diagram illustrating a control unit according to the second embodiment. In addition, description is simplified by attaching | subjecting the same referential mark to the already demonstrated location. The control unit 800 is a control unit of the paper discharge option device 700.

  The option control unit 810 communicates with the engine control unit 202 and controls each unit in the paper discharge option device 700. A conveyance control unit 803 drives a paper conveyance system inside the paper discharge option device. The conveyance control unit 803 controls, for example, a flapper driving motor 804 that individually drives the flappers 730 and 739 to 741. The option control unit 801 obtains detection results from various sensors inside the paper discharge option device such as the reverse sensor 732.

  FIG. 9 is a flowchart showing the paper transport control of the paper discharge option device according to the second embodiment.

  In step 901, the option control unit 801 waits until a carry-in advance notice command is received from the engine control unit 202. The carry-in advance command is a command for notifying that the recording paper is carried from the image forming apparatus 100 to the paper discharge option device 700. When the carry-in advance command is received, the process proceeds to step 902.

  In step 902, the option control unit 801 determines whether or not the face-down paper discharge trays 736 to 738 are designated as paper discharge destinations based on the information received from the engine control unit 202. Note that the conveyance path to the paper discharge trays 736 to 738 has a curved section in a part thereof, and is a conveyance path capable of conveying flexible recording paper. If the paper discharge trays 736 to 738 are designated, the process proceeds to step 903. On the other hand, if the paper discharge trays 736 to 738 are not designated, the option control unit 801 ends the processing according to this flowchart. That is, if the face-up discharge tray 742 is designated as the discharge destination, the switching of the flapper 730 is not executed. This is because the conveyance path to the paper discharge tray 742 is almost straight and the flexibility of the recording paper is not required. That is, the conveyance path to the paper discharge tray 742 is a conveyance path for discharging recording paper that does not have flexibility.

  In step 903, the option control unit 801 determines whether the thickness of the recording paper exceeds a predetermined threshold value. Note that the option control unit 801 may receive information on the thickness of the recording paper from the engine control unit 202. Alternatively, the option control unit 801 may receive a determination result from the engine control unit 202 as to whether or not the recording paper thickness exceeds a predetermined threshold.

  Note that the threshold value is the thickness of the recording paper that is difficult or substantially impossible to convey to the paper discharge trays 736 to 738. Therefore, this threshold value depends on the curvature of the curved portion of the conveyance path to the paper discharge trays 736 to 738, the friction coefficient, and the like. It may also be desirable to determine the threshold experimentally for each optional device. If the detected thickness does not exceed the threshold value, the processing according to this flowchart is terminated without switching the flapper 123. On the other hand, if the detected thickness exceeds the threshold, the process proceeds to step 904.

  In step 904, the option control unit 801 sends a switching command for the flapper 730 to the transport control unit 803 in order to switch the paper discharge destination to the paper discharge tray 742. The transport controller 803 drives the flapper drive motor 804 in response to this command. As a result, the conveyance path of the recording paper is switched to the conveyance path provided with the discharge tray 742 at the end.

  As described above, according to the present embodiment, the transport path in the paper discharge option device can also be suitably switched based on the parameters relating to the flexibility of the recording paper. Thereby, the occurrence of a jam in the paper discharge option device can be suitably reduced.

  Note that a sensor for detecting a parameter relating to the flexibility of the recording paper may be provided in the paper discharge option device 700. In this case, even when the image forming apparatus 100 is not provided with the sensor, the paper discharge option device 700 can reduce the occurrence of a jam in the paper discharge option device.

  Needless to say, the first embodiment and the second embodiment may be combined. For example, a recording sheet that should be discharged to the face-down discharge tray 128 may be discharged to the face-up discharge tray 742.

  In each of the embodiments described above, a printer is used as an example of the image forming apparatus 100. However, the image forming apparatus according to the present invention may be a copying machine, a multifunction machine, a facsimile machine, or the like.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment. It is a block diagram which shows the control part which concerns on embodiment. It is a figure which shows an example of a paper thickness sensor. It is a figure showing the relationship between the output signal from a position detection element, and its positional information. FIG. 3 is a circuit diagram illustrating a portion of an exemplary paper thickness sensor. It is a flowchart which shows the paper conveyance control which concerns on embodiment. It is a figure which shows schematic structure of the image forming apparatus which concerns on 2nd Embodiment. It is a block diagram which shows the control part which concerns on 2nd Embodiment. 10 is a flowchart illustrating sheet conveyance control of a sheet discharge option device according to a second embodiment.

Claims (7)

A plurality of conveyance paths for conveying recording paper;
A plurality of paper discharge sections provided corresponding to each of the plurality of transport paths;
A detection unit for detecting a parameter relating to the flexibility of the recording paper;
An image forming apparatus comprising: a switching unit that switches the conveyance path according to a parameter detected by the detection unit. The plurality of paper discharge units are
A first paper discharge unit corresponding to a conveyance path that requires relatively flexibility with respect to the recording paper;
A second paper discharge unit corresponding to a conveyance path that does not require flexibility relative to the recording paper,
The switching unit switches the conveyance path so that the recording paper is discharged to the second paper discharge unit when the parameter relating to the recording paper to be discharged exceeds a threshold value. The image forming apparatus described in 1.   If the parameter relating to the recording paper to be discharged exceeds a threshold value, the switching unit is configured to discharge the recording paper to the first paper discharging unit even if it is designated in advance. The image forming apparatus according to claim 2, wherein the conveyance path is switched so that the recording paper is discharged to a paper portion.   The image forming apparatus according to claim 1, wherein the parameter is a thickness, weight, stiffness, or density of the recording paper. An image forming system including a paper discharge option device and an image forming apparatus to which the paper discharge option device can be connected,
A plurality of conveyance paths for conveying the recording paper provided in the paper discharge option device;
A plurality of paper discharge units provided corresponding to each of the transport paths in the paper discharge option device;
A detection unit for detecting a parameter relating to the flexibility of the recording paper;
An image forming system comprising: a switching unit that switches the conveyance path in accordance with the parameter detected by the detection unit. A paper discharge option device attached to the image forming apparatus,
A plurality of conveyance paths for conveying recording paper;
A plurality of paper discharge units provided corresponding to each of the conveyance paths;
A paper discharge option device comprising: a switching unit that switches the conveyance path according to a parameter relating to flexibility of the recording paper detected in the image forming apparatus or the paper discharge option device. A control method of an image forming apparatus having a plurality of transport paths and a paper discharge unit corresponding to each of the transport paths,
A detection process for detecting parameters relating to the flexibility of the recording paper;
And a switching step of switching the transport path according to the detected parameter.

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