JP4640100B2 - Sheet size detection apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a sheet size detection apparatus and an image forming apparatus, and more specifically, a sheet size applied to a sheet size detection apparatus that detects the size of a sheet-like recording medium such as a sheet stacked on a sheet feeding unit. The present invention relates to a detection apparatus and an image forming apparatus that forms an image on a sheet-like recording medium whose size is detected.

In a paper size detection device that is mounted on an image forming apparatus and detects the size of an image forming paper loaded on a paper feeding unit, a replaceable identification member for identifying the paper size is provided according to the paper size. The identification member is detected by a switch provided in the image forming apparatus (for example, see Patent Document 1), or the position of the paper guide is changed according to the paper size, and a plurality of switches are used. The paper size is detected based on a combination of ON / OFF switching of a plurality of switches, such as detecting the guide position (see, for example, Patent Documents 2 and 3).
JP-A-4-59517 Japanese Patent Laid-Open No. 5-92820 JP-A-5-132154

  However, in the above configuration, when trying to increase the number of switches to cope with an increase in the types of paper sizes to be detected, if digital ports are used for all switches, the number of ports is required by the number of switches. Circuit design becomes complicated. In addition, since there is usually an upper limit on the number of I / O ports, other necessary ports are insufficient. Also, if all ports are input via a single A / D conversion port, the number of switches that can be used is limited because the resolution is limited due to variations in resistance values and the accuracy of A / D conversion. There is a problem that the number of types of paper sizes that can be detected cannot be increased.

  In consideration of the above-described facts, the present invention provides a sheet size detection device and an image forming apparatus that can detect more types of sheet sizes while suppressing the number of input ports required to detect the sheet size. The task is to do.

In order to achieve the above object, the invention according to claim 1 is a size identification means including a side guide for identifying the size in the width direction of the sheet, and an end guide for identifying the size in the sheet conveyance direction. , A plurality of switches that can be switched ON / OFF according to the operation of the size identification means are provided, and the resistance value of the switch circuit is changed by changing the combination of the resistances of the switch circuit by switching each switch ON / OFF. And a switch set for converting an analog signal corresponding to the resistance value to a digital signal via an A / D conversion circuit and outputting the digital signal, and an ON / OFF signal to the digital port according to the operation of the size identification means to detect the size of the sheet on the basis of one or more switches for outputting, to the output of the said switch set of output switches And an end actuator that is moved by operating the end guide and formed with a stepped groove, and outputs ON / OFF to the digital port. The above switches are turned on / off in contact with or separated from the stepped groove of the end actuator, and the switch set has different heights with respect to the stacking direction of the sheet members, and transports the sheet. And two switches which are arranged at the same position with respect to the direction and which are turned on / off in contact with or separated from the stepped groove of the end actuator.

  In the present invention, for example, the sheet size is identified by size identifying means such as a guide or an actuator that changes the position according to the sheet size, and the switch unit turns on / off a plurality of switches according to the identification result. Is switched.

  Here, in the switch set provided in the switch unit, the resistance value of the switch circuit is changed by changing the combination of the resistances of the switch circuit by switching ON / OFF of each switch, and the analog value corresponding to the resistance value is changed. The signal is converted into a digital signal via an A / D conversion circuit and output. In one or more switches provided in the switch unit, an ON / OFF signal is directly output to the digital port.

  As a result, in this switch unit, since a large number of signal output patterns can be obtained for a small number of ports by switching each switch ON / OFF, the number of input ports required to detect the sheet size is suppressed. However, more types of sheet sizes can be detected.

The image forming apparatus according to the invention of claim 2 is an image in claims including a sheet size detecting device according to claim 1, the image forming section to a sheet-like recording medium in which size is detected by the sheet size detecting device It is characterized by forming.

  If the image forming apparatus includes the above sheet size detection device, the above sheet size detection device can detect the size of a larger number of types of sheet-like recording media. It is possible to cope with image formation on a recording medium.

  According to the sheet size detection apparatus and the image forming apparatus of the present invention, it is possible to detect more types of sheet sizes while suppressing the number of input ports necessary for detecting the sheet size.

  Hereinafter, a sheet feeding device to which a sheet feeding apparatus according to an embodiment of the present disclosure is applied and an image forming apparatus equipped with the sheet feeding device will be described with reference to the drawings.

  An image forming apparatus 10 according to this embodiment shown in FIG. 1 is a copying machine using an electrophotographic system. As shown in the drawing, a document placed on a document tray is imaged on the upper surface of an image forming apparatus main body 12. An automatic document feeder 14 is provided that automatically feeds the document to the reading position and automatically ejects it after reading the image.

  Inside the image forming apparatus main body 12, a document reading unit 16 that reads an image of a document sent from the automatic document feeder 14 and converts it into an image signal, and an image (paper) based on the image signal from the document reading unit 16. An image forming unit 18 that forms a toner image), a paper feeding device 20 that supplies paper to the image forming unit 18, and a paper aligning device 80 that corrects bending in the transport direction of the paper supplied to the image forming unit 18 Is provided.

  As shown in FIG. 2, the paper feeder 20 has two small paper cassettes 22A, 22B, A3 size and other large size papers PL in which small size paper PS such as A4 size and letter size frequently used is stored. Large paper cassettes 24A and 24B, and paper feed mechanisms 26A, 26B, 26C, and 26D that send out paper P (PS, PL) from these paper feed cassettes 22A, 22B, 24A, and 24B. A paper transport path 28 for guiding the paper P to the image forming section 18 and a plurality of transport roll pairs 30 for transporting the paper to the image forming section 18 side along the paper transport path 28 are provided.

  The small paper cassettes 22A and 22B have the same configuration and common components, and have the same paper feed capacity and accommodate a large amount (for example, 1500 sheets) of small-size paper PS stacked. Is done. In addition, each of the paper cassettes 22A on the upstream side (the right side in FIG. 2) is located on the downstream side (the left side in FIG. 2). ) Are slightly above the paper feed cassette 22B and are arranged in steps.

  Inside the paper feed cassettes 22 </ b> A and 22 </ b> B, there is provided a tray 32 that can be moved up and down by an elevating mechanism (not shown) using a motor as a drive source, and small-size paper PS is stacked on the tray 32. Are accommodated in the paper feed cassettes 22A and 22B.

  The large paper cassettes 24A and 24B are arranged in substantially two layers above the paper cassettes 22A and 22B arranged in parallel, and are accommodated in a state in which large-size papers PL are stacked.

  The paper feed mechanisms 26 (26A to 26D) provided corresponding to the paper feed cassettes 22A, 22B, 24A, and 24B have the same configuration and share components. The paper feed mechanism 26 includes a pickup roll 34 for feeding the uppermost paper P in the paper feed cassette in the paper feed direction, a feed roll 36 and a retard roll 38 for feeding the fed paper P one by one, Is provided with a support mechanism that rotatably supports each of these rolls, a motor as a drive source for rotationally driving each roll, and a rotational force transmission mechanism that transmits the rotational force of the motor to each roll. These parts are housed in a frame 40.

  Further, for the paper feed mechanism 26A corresponding to the upstream paper feed cassette 22A, the lower frame 40A constituting the lower surface portion of the frame 40 is a small size paper PS stacked on the tray 32 of the downstream paper feed cassette 22B. It is arranged close to the upper end with respect to the rear end portion.

  Above the sheet feeding device 20, a sheet aligning device 80 is connected to the downstream end (upper end portion) of the sheet conveying path 28, and the sheet aligning apparatus 80 includes a sheet P (PS) from the sheet conveying path 28. , PL) is sent.

  The sheet aligning device 80 includes a sheet conveying path 82 that connects between the sheet conveying path 28 on the paper feeding apparatus 20 side and the image forming unit 18, and a pair of conveying rolls (auxiliary rolls) that are disposed on the upstream side of the sheet conveying path 82. ) 84 and a pair of resist rolls (correction rolls) 86 disposed on the downstream side, although not shown, a support mechanism that rotatably supports each of these rolls, a motor as a drive source that rotationally drives each roll, and A rotational force transmission mechanism that transmits the rotational force of the motor to each roll is provided, and the paper P is transported to the downstream side by the rotation of the transport roll 84. Thus, the bending of the paper P with respect to the transport direction is corrected (loop aligning). Then, the registration roll 86 and the transport roll 84 are rotated at a predetermined timing (image formation timing) after the bending correction, and the paper P is fed into the image forming unit 18.

  Further, the paper transport system of the image forming apparatus 10 transports the paper P with a substantially central reference in the width direction of the paper transport paths 28 and 82, that is, in a state where the approximate center in the paper width direction is aligned with the approximate center. It is a center cash register method for transporting.

  The image forming apparatus 10 has the above-described configuration. In the image forming apparatus 10, an image of a document sent from the automatic document feeder 14 is converted into a read image signal by the document reading unit 16, and the image signal is converted into the image signal. Based on this, the image forming unit 18 feeds the paper feed cassettes 22A, 22B, 24A, and 24B by the paper feed mechanisms 26A, 26B, 26C, and 26D, transports the paper transport path 28 by the transport roll pair 30, and the paper aligning device 80. An image of the original is copied onto the paper P by forming an image on the supplied paper P with the bending in the conveyance direction corrected.

(First embodiment)
Next, the paper size detection apparatus according to the first embodiment of the present invention will be described in detail by taking the above-described paper feed cassette 24A provided with the size identification mechanism of the paper size detection apparatus as an example.

  As shown in FIG. 3, the paper feed cassette 24A is slidably attached to the image forming apparatus main body 12 in a direction (arrow A / B direction) orthogonal to the paper transport direction (arrow Y direction). The paper P is loaded and accommodated on the placement surface 25 in the cassette in a state where the paper feed cassette 24A is pulled out from the image forming apparatus main body 12 (arrow A direction), and the paper feed cassette 24A is stored in the image forming apparatus main body. When pushed into 12, supply from within the cassette becomes possible.

  On the placement surface 25, a pair of slides that slide in the left-right direction (arrow C direction) that is orthogonal to the paper transport direction and abut against the side edges of the paper P to regulate the placement position in the paper width direction. The side guides 102A and 102B and an end guide 104 that slides in the front-rear direction (arrow D direction), which is parallel to the paper transport direction, contacts the rear end of the paper P and regulates the placement position in the paper transport direction. The size identifying mechanism 100 for identifying the size of the paper P includes the side guides 102A and 102B and the end guide 104.

  As shown in FIG. 4, a pair of racks 110 </ b> A and 110 </ b> B are provided at the lower ends of the side guides 102 </ b> A and 102 </ b> B so as to extend toward the center of the cassette along the left-right direction. The rack surfaces are opposed to each other and meshed with the two pinion gears 112.

  An engagement protrusion 114 is provided on the rear end side of the side guide 102B disposed on the rear side in the cassette. A slide plate 116 slidably mounted in the front-rear direction is disposed on the rear end side of the side guide 102B. The slide plate 116 extends in the left-right direction and is formed in a substantially step shape. The guide hole 118 is connected to the side guide 102 </ b> B by being engaged with the engaging protrusion 114. Further, a side actuator 120 is provided at an end on the back side of the slide plate 116, and the side actuator 120 includes two switch pressing portions that are arranged at a predetermined interval in the front-rear direction and protrude toward the back. 122A and 122B are provided.

  Accordingly, when the user slides the side guide 102A disposed on the labor side in the cassette, the side guide 102B slides in the reverse direction in conjunction with the slide operation, and the pair of side guides 102A and 102B is moved on the placement surface 25. The placement position in the paper width direction is regulated by contacting the side edge of the paper P placed on the paper. Further, in conjunction with the side guides 102A and 102B, the slide plate 116 slides in the front-rear direction, and accordingly, the side actuator 120 also slides in the front-rear direction.

  On the other hand, the end guide 104 is arranged on one end side (cassette rear side) of the link 124 that extends linearly, and an engagement protrusion (not shown) provided on the lower surface portion is provided on one end portion of the link 124. By being fitted into and engaged with the formed guide hole 126, it is connected to one end of the link 124.

  As shown in FIG. 5, an end actuator 130 slidably mounted in the front-rear direction is disposed on the other end portion side (cassette back side) of the link 124, and the end actuator 130 is disposed on the lower surface portion. An engagement protrusion (not shown) provided is connected to the other end portion of the link 124 by being fitted into and engaged with a guide hole 128 formed in the other end portion of the link 124.

  The end actuator 130 is formed with two openings arranged at a predetermined interval in the front-rear direction, and the switch press release parts 132A and 132B are formed by the openings. One switch pressing release portion 132A opens in a straight line along the front-rear direction, which is the operation direction of the end actuator 130, corresponding to the push switches 144D and 144E of the switch unit 140, and the other switch press releasing portion As for 132B, the press release part of each switch is opening along the front-back direction corresponding to push switch 144C-144E.

  The link 124 connecting the end guide 104 and the end actuator 130 has a shaft 136 in which a circular hole 134 formed slightly closer to the end actuator 130 than the center portion is provided on the bottom surface of the paper feed cassette 24A. Is attached so as to be rotatable about the shaft 136.

  Thus, when the user slides the end guide 104, the link 124 rotates and the end actuator 130 slides in the reverse direction in conjunction with the end guide 104. By placing the end guide 104 in contact with the rear end portion of the paper P placed on the placement surface 25, the placement position in the paper conveyance direction is regulated.

  In the present embodiment, the size identification mechanism 100 is configured by the side guides 102A and 102B, the end guide 104, the slide plate 116, the side actuator 120, the link 124, the end actuator 130, and the like described above.

On the other hand, in the image forming apparatus main body 12, as shown in FIGS. 3 to 5, a switch unit 140 is attached at a position corresponding to the side actuator 120 and the end actuator 130 (see FIG. 3).
As shown in FIG. 6, the switch unit 140 has five push switches 144 </ b> A to 144 </ b> E mounted on one surface of the substrate 142 facing the actuators 120 and 130. Among the push switches 144A to 144E, the two push switches 144A and 144B arranged in parallel on the upper side correspond to the side actuator 120, and the central push switch 144C and the two push switches arranged in parallel on the lower side. A total of three switches 144D and 144E correspond to the end actuator 130.

  A switch circuit 150 shown in FIG. 7A is formed on the substrate 142 of the switch unit 140. In this switch circuit 150, four push switches 144A to 144D (SW1 to SW4) are set as one set, and the combination of resistances (R1 to R4, etc.) of the switch circuit 150 is changed by switching each switch ON / OFF. Then, when the resistance value of the switch circuit 150 is changed, the output voltage changes with respect to the supply voltage (5 V) from the power source. The analog voltage signal is output to the A / D conversion port 1 in a controller (not shown) in the image forming apparatus 10. Thereby, the analog voltage signal is converted into a digital signal via the A / D conversion circuit.

  The remaining one push switch 144E directly outputs an ON / OFF (High / Low) signal to the digital port of the controller.

  The switch unit 140 is configured as described above, and the paper size detection device 90 is configured by the switch unit 140 and the size identification mechanism 100 described above (see FIG. 4).

  Next, paper size detection and its operation by the sheet size detection device 90 of this embodiment will be described.

  As described above, when the side guides 102A and 102B of the paper feed cassette 24A are slid, the side actuator 120 slides, and the switches for the push switches 144A and 144B of the switch unit 140 as shown in FIG. 8A. The relative positions of the pressing parts 122A and 122B are changed. Thereby, pressing / release of push switches 144A and 144B by switch pressing parts 122A and 122B is switched, and ON / OFF of push switches 144A and 144B is switched.

  Further, when the end guide 104 is slid, the end actuator 130 is slid, and as shown in FIG. 8B, switch pressing release portions 132A and 132B (opening portions) for the push switches 144C to 144E of the switch unit 140. The relative position of is changed. Accordingly, the push actuators 144C to 144E are switched to be pressed / released by the end actuator 130 and the switch pressing release portions 132A and 132B, and the push switches 144C to 144E are switched ON / OFF.

  As shown in FIG. 7B, the analog voltage level output from the switch circuit 150 to the A / D conversion port of the controller is 0 to 0 by switching the ON / OFF of the push switches 144A to 144D as one set. It changes in 16 steps up to 4.66 (V). Further, the high / low of the signal output to the digital port of the controller is switched by the ON / OFF switching of the push switch 144E.

  As a result, in this switch unit 140, it is possible to output 32 patterns of signals to two ports by switching ON / OFF of five switches. In the sheet size detection device 90, 32 types of paper sizes are available at the maximum. Detection is possible.

  As described above, in the sheet size detection device 90 of the present embodiment, the number of input ports necessary for detecting the paper size can be suppressed, and more types of paper sizes can be detected. Further, the image forming apparatus 10 of this embodiment provided with the sheet size detecting device 90 can cope with image formation on more types of paper P.

(Second Embodiment)
Next, a second embodiment of the present invention will be described.

  FIG. 9A shows a switch circuit configured in the switch unit of the present embodiment.

  As shown in FIG. 9A, in the present embodiment, the switch unit 160 is provided with six push switches (SW1 to SW6), and two switch circuits 160A and 160B each including three switches are configured. Has been.

  In one switch circuit 160A, the resistance value of the switch circuit 160A is changed by changing the combination of resistors (R1 to R3, etc.) by switching ON / OFF of the three push switches (SW1 to SW3). The output voltage changes with respect to the supply voltage (5V) from The analog voltage signal is output to the A / D conversion port 1 of the controller.

  Similarly, in the other switch circuit 160A, the resistance value of the switch circuit 160B is changed by changing the combination of resistors (R4 to R6, etc.) by switching ON / OFF of the three push switches (SW4 to SW6). The output voltage is changed with respect to the supply voltage (5 V) from the power source. The analog voltage signal is output to the A / D conversion port 2 of the controller.

  Further, with respect to such six push switches (SW1 to SW6), in the size identification mechanism described in the first embodiment, each switch is turned on by changing the shape of each side and end actuator. It is configured so that / OFF switching is possible.

  As described above, in this embodiment, the ON / OFF switching of the two sets of push switches (SW1 to SW3 / SW4 to SW6) constituting the two switch circuits 160A and 160B is shown in FIGS. 9B and 9C. As described above, the analog voltage level output from the switch circuits 160A and 160B to the A / D conversion ports 1 and 2 of the controller changes from 0 to 4.66 (V) in 8 steps. As a result, in this switch unit 160, it is possible to output 64 patterns of signals to the two ports by switching on / off the six switches, and the sheet size detection device can detect a maximum of 64 types of paper sizes. Is possible.

  Further, in the circuit configuration of the present embodiment, the voltage level per step can be increased (about twice) as compared with the circuit of the first embodiment, and therefore depends on the resistance value variation and the accuracy of A / D conversion. A margin for the resolution can be secured, and the circuit design becomes easy.

  Although the present invention has been described in detail with the first and second embodiments described above, the present invention is not limited to them, and various other modes can be implemented within the scope of the present invention. is there.

  Further, the present invention is not limited to the above-described copying machine, but can be applied to other image forming apparatuses such as a laser printer and an ink jet printer, and a paper size detecting apparatus mounted on these printers. Furthermore, the present invention is not limited to the above-described paper size detection device that detects the size of a sheet-like recording medium, but is also applied to a sheet size detection device that detects the size of the sheet in order to process a sheet such as a polymer film. Can be applied.

1 is a configuration diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a configuration diagram illustrating a schematic configuration of a paper feeding device and a paper aligning device installed in the image forming apparatus of FIG. 1. FIG. 3 is a perspective view showing a paper feed cassette provided with a size identification mechanism of the paper size detection device according to the first embodiment of the present invention. 1 is a perspective view showing a paper size detection device according to a first embodiment of the present invention. FIG. 5 is a perspective view showing a size identification mechanism and a switch unit on the end guide side in the paper size detection device of FIG. 4. FIG. 5 is a front view showing a switch unit provided in the paper size detection device of FIG. 4. (A) is a circuit diagram which shows the switch circuit formed in the switch unit which concerns on the 1st Embodiment of this invention, (B) is a table | surface figure which shows the output pattern of the voltage level output from the switch circuit of (A) It is. (A), (B) is explanatory drawing explaining the combination of ON / OFF switching of the five push switches provided in the switch unit which concerns on the 1st Embodiment of this invention. (A) is a circuit diagram which shows the switch circuit formed in the switch unit which concerns on the 2nd Embodiment of this invention, (B), (C) is an output pattern of the voltage level output from the switch circuit of (A) FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 18 Image forming part 90 Paper size detection apparatus (sheet size detection apparatus)
100 Size identification mechanism 102A, 102B Side guide 104 End guide 116 Slide plate 120 Side actuator 122A, 122B Switch pressing part 124 Link 130 End actuator 132A, 132B Switch pressing release part 140 Switch units 144A-144E Push switch 150 Switch circuit 160 Switch unit 160A, 160B Switch circuit P Paper (sheet / recording medium)
PS paper (sheet / recording medium)
PL paper (sheet / recording medium)

Claims (2)

A size identifying means configured to include a side guide for identifying the size in the width direction of the sheet, and an end guide for identifying the size in the conveyance direction of the sheet;
A plurality of switches that can be switched ON / OFF according to the operation of the size identification means are provided, and the resistance value of the switch circuit is changed by changing the combination of the resistances of the switch circuit by switching each switch ON / OFF. A switch set that is changed and converts an analog signal corresponding to the resistance value into a digital signal via an A / D conversion circuit and outputs the digital signal;
One or more switches for outputting an ON / OFF signal to the digital port in response to an operation of the size identifying means ;
A controller that detects a sheet size based on an output result of the switch set and an output result of the switch;
The end guide is connected to an end actuator that is moved by operating the end guide and has a stepped groove formed therein.
One or more switches that output ON / OFF to the digital port are turned on / off by contacting or separating from the stepped groove of the end actuator,
The switch set includes
ON / OFF at different heights with respect to the stacking direction of the sheet members, at the same position with respect to the sheet conveying direction, and in contact with or apart from the stepped groove of the end actuator. Two switches to be
A sheet size detection apparatus comprising: An image forming apparatus comprising the sheet size detecting device according to claim 1, wherein an image forming unit forms an image on a sheet-like recording medium whose size is detected by the sheet size detecting device.

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