JP6217574B2 - Image reading apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image reading apparatus that reads an image formed on a recording medium, and an image forming apparatus that forms an image on recording paper.

  2. Description of the Related Art Conventionally, as an image reading apparatus that reads an image formed on a recording medium, an image reading apparatus including an automatic conveyance unit and an image reading unit is known. The automatic conveying unit has a document tray on which documents are placed. The image reading unit has a first reading position for reading a document conveyed from the automatic conveying unit and a second reading position for reading an individual document.

  In such an image forming apparatus, an image reading apparatus with a reduced number of sensors is disclosed (see Patent Document 1). In the image reading apparatus described in Patent Document 1, the open / close state of the pressure plate for pressing the document on the document table is determined by monitoring the pixel level of a specific spot outside the document placement area.

  Patent Document 1 describes that according to this image reading apparatus, a pressure plate opening / closing sensor that has been conventionally required can be removed, which is advantageous in terms of cost.

JP 2007-110655 A

  However, in the image reading apparatus described in Patent Document 1, since the lamp is irradiated when monitoring the pixel level of a specific spot outside the document placement area, it may be dazzling for the user when the pressure plate is open. is there. Further, since the open / close state of the pressure plate is determined by monitoring the pixel level of a specific spot, complicated processing is required.

  SUMMARY An advantage of some aspects of the invention is that it provides an image reading apparatus and an image forming apparatus that can reduce the number of sensors with a simple configuration.

  An image reading apparatus of the present invention is an image reading apparatus that reads an image formed on a document, and includes an automatic conveyance unit, an image reading unit, a first cover, a second cover, a first sensor, a second sensor, and a third sensor. And a determination unit. The automatic conveyance unit has a document tray on which documents are placed. The image reading unit has a first reading position for reading a document conveyed from the automatic conveying unit and a second reading position for reading an individual document. The first cover covers the first reading position and the second reading position so as to be freely opened and closed. The second cover covers the document transport path from the document tray to the first reading position of the image reading unit so as to be freely opened and closed. The first sensor outputs ON when the first condition that both the first cover and the second cover are closed satisfies the first condition, and outputs OFF when the first condition is not satisfied. . The second sensor outputs OFF when no document is placed on the document tray and the second condition that the second cover is closed satisfies the second condition. If it does not exist, ON is output. The third sensor outputs OFF when there is no document in the transport path and the third condition that the second cover is closed, and when the third condition is not satisfied, the third sensor outputs Outputs ON. The determination unit determines whether the first cover and the second cover are opened or closed based on outputs of the second sensor and the third sensor before and after the first sensor changes from on to off. judge.

  An image forming apparatus of the present invention is an image forming apparatus that forms an image on a recording sheet, and includes an automatic conveyance unit, an image reading unit, a first cover, a second cover, a first sensor, a second sensor, a third sensor, And a determination part is provided. The automatic conveyance unit has a document tray on which documents are placed. The image reading unit has a first reading position for reading a document conveyed from the automatic conveying unit and a second reading position for reading an individual document. The first cover covers the first reading position and the second reading position so as to be freely opened and closed. The second cover covers the document transport path from the document tray to the first reading position of the image reading unit so as to be freely opened and closed. The first sensor outputs ON when the first condition that both the first cover and the second cover are closed satisfies the first condition, and outputs OFF when the first condition is not satisfied. . The second sensor outputs OFF when no document is placed on the document tray and the second condition that the second cover is closed satisfies the second condition. If it does not exist, ON is output. The third sensor outputs OFF when there is no document in the transport path and the third condition that the second cover is closed, and when the third condition is not satisfied, the third sensor outputs Outputs ON. The determination unit determines whether the first cover and the second cover are opened or closed based on outputs of the second sensor and the third sensor before and after the first sensor changes from on to off. judge.

  According to the image reading apparatus and the image forming apparatus of the present invention, the number of sensors can be reduced with a simple configuration.

1 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an arrangement of three sensors in the image forming apparatus illustrated in FIG. 1. 3 is a chart showing a relationship between outputs of three sensors shown in FIG. 2 and determination results. It is a flowchart which shows operation | movement of the determination part shown in FIG. FIG. 5 is a flowchart (first half) showing in detail a process of determination processing in step S107 of the flowchart shown in FIG. 4; FIG. 5 is a flowchart (second half) showing in detail a process of determination processing in step S107 of the flowchart shown in FIG. 4;

  Embodiments of the present invention will be described below with reference to the drawings (FIGS. 1 to 6). In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof is not repeated.

  First, an image forming apparatus 100 according to the present embodiment will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration of an image forming apparatus 100 according to the present embodiment. Here, the image forming apparatus 100 is a multi-function peripheral (MFP). The image forming apparatus 100 has functions of a scanner, a copier, a printer, and a facsimile. The image forming apparatus 100 includes an image forming unit 1, an image reading unit 2, a document transport unit 3, an operation panel 4, and a control unit 5. The operation panel 4 includes a touch panel 41. The control unit 5 includes a determination unit 51.

  The image forming unit 1 forms an image on a recording sheet P that is an example of a recording medium. The image reading unit 2 reads an image formed on a document. The document transport unit 3 transports a document to be read. The operation panel 4 includes a touch panel 41 and receives an operation from the user for the image forming apparatus 100. The control unit 5 controls the operation of the entire image forming apparatus 100.

  The image forming unit 1 includes a paper feed cassette 11, a paper feed roller 12, a transport roller 13, a registration roller 14, an image forming unit 15, a fixing device 16, a discharge roller 17, and a discharge tray 18. The paper feed roller 12 feeds the recording paper P from the paper feed cassette 11 one by one. The recording paper P fed out by the paper supply roller 12 is conveyed to the image forming unit 15 by the conveyance roller 13 and the registration roller 14.

  The image forming unit 15 forms an image on the recording paper P conveyed from the paper feed cassette 11. The image forming unit 15 includes a photosensitive drum 151, a charging unit 152, an exposure unit 153, a developing unit 154, a transfer roller 155, and a cleaning unit 156. The photosensitive drum 151 is a cylindrical rotating body, and an electrostatic latent image is formed on the peripheral surface thereof. The charging unit 152 charges the photosensitive drum 151 to a predetermined potential. The exposure unit 153 irradiates the photosensitive drum 151 with laser light based on the image data to form an electrostatic latent image corresponding to the image data on the photosensitive drum 151. As the image data, for example, image data generated by the image reading unit 2 reading a document, or image data received from an external computer via a communication network (not shown) is used. The recording paper P on which the image is formed by the image forming unit 15 is conveyed to the fixing device 16.

  The developing unit 154 supplies toner to the electrostatic latent image formed on the photosensitive drum 151 and develops it, thereby forming a toner image on the photosensitive drum 151. The transfer roller 155 transfers the toner image on the photosensitive drum 151 onto the recording paper P. The cleaning unit 156 removes residual toner remaining on the photosensitive drum 151 after the transfer.

  The fixing device 16 thermally fixes the image formed on the recording paper P to the recording paper P. The fixing device 16 includes a heating roller containing a heating element and a pressure roller. The heating roller and the pressure roller form a fixing nip portion by being pressed against each other. As the recording paper P passes through the fixing nip portion, the toner adhering to the surface of the recording paper P is melted and heated, and the toner image is fixed on the recording paper P. The recording paper P on which the toner image is fixed is discharged to a discharge tray 18 by a discharge roller 17.

  The controller 5 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). A control program is stored in the ROM. The CPU functions as various functional units including the determination unit 51 by reading and executing the control program stored in the ROM. The RAM is used as a work area when the CPU executes the control program.

  Next, with reference to FIG. 2, the image reading unit 2 and the document transport unit 3 will be described, and then the three sensors S1 to S3 will be described. FIG. 2 is a diagram showing the arrangement of the three sensors S1 to S3 in the image forming apparatus 100 shown in FIG. Here, the image reading unit 2 and the document conveying unit 3 correspond to an example of an “image reading apparatus”.

  The image reading unit 2 includes a contact glass 210, a light source 22, a first mirror 231, a second mirror 232, a third mirror 233, a first carriage 26, a second carriage 27, an imaging lens 28, and a CCD (Charge Coupled Device) 29. And a first sensor S1. The light source 22 and the first mirror 231 are supported by the first carriage 26, and the second mirror 232 and the third mirror 233 are supported by the second carriage 27. The contact glass 210 has a wide document placing glass 212 and a long and narrow document automatic reading glass 211 located on the left side of the document placing glass 212 in FIG.

  There are two types of document reading methods by the image reading unit 2: a flatbed reading mode and an ADF (Auto Document Feeder) reading mode. In the flat bed reading mode, an image of a document placed on the document placement glass 212 is read. In the ADF reading mode, the original is conveyed by the original conveying unit 3, and the original image is read when the original passes the first reading position 211a.

  Specifically, in the flat bed reading mode, the light source 22 irradiates a document placed on the document placement glass 212, and reflected light from the document is reflected by the first mirror 231, the second mirror 232, The light is reflected in the order of the three mirrors 233 and enters the imaging lens 28. The light incident on the imaging lens 28 is imaged by photoelectric conversion on the light receiving surface of the CCD 29 and output as an image signal. Here, the upper surface of the document placement glass 212 corresponds to an example of a “second reading position”. When reading for one line is completed, the first carriage 26 and the second carriage 27 move in a direction (sub-scanning direction, arrow Y direction) orthogonal to the main scanning direction of the document (direction perpendicular to the paper surface of FIG. 2). Then, the next line is read.

  On the other hand, in the ADF reading mode, when the original conveyed by the original conveying unit 3 passes through the first reading position 211a that is the gap between the automatic document reading glass 211 and the reading guide 36 as described later, 22 irradiates the original with light via the automatic original reading glass 211. Here, the first reading position 211a corresponds to an example of a “first reading position”. Then, the reflected light from the original is reflected in the order of the first mirror 231, the second mirror 232, and the third mirror 233, enters the imaging lens 28, and the light incident on the imaging lens 28 is the light receiving surface of the CCD 29. And imaged by photoelectric conversion and output as an image signal. When the reading for one line is completed, the original is conveyed by the original conveying unit 3 and the next line is read.

  As shown in FIG. 2, the document transport unit 3 includes an open / close cover C2, a document tray 31, a pickup roller 32, a separation roller 33, a transport roller 34, a registration roller 35, a reading guide 36, a transport roller 37, a discharge roller 38, and A document discharge tray 39 is provided to constitute an ADF. The document transport unit 3 includes a second sensor S2 and a third sensor S3. Here, the document conveyance unit 3 corresponds to an example of an “automatic conveyance unit”. As will be described later, the document transport unit 3 corresponds to an example of a “first cover”.

  The opening / closing cover C <b> 2 is a cover that covers the document conveyance path from the document tray 31 to the first reading position 211 a of the image reading unit 2 in the document conveyance unit 3 so as to be freely opened and closed. Here, the opening / closing cover C2 corresponds to an example of a “second cover”. For example, when a paper jam (hereinafter, also referred to as “jam”) occurs in the transport path, the user opens the open / close cover C2 (the state indicated by the phantom line in FIG. 2) and removes the document from the transport path. Can be removed.

  The document tray 31 is a place where a plurality of documents are placed. On the bottom surface of the document tray 31, there is provided a lift mechanism (not shown) that lifts the document upward, for example, by moving the lift plate with an upward biasing force. When the document is placed on the document tray 31, the lift plate is lifted upward by a lift mechanism (not shown), and the uppermost document contacts the pickup roller 32.

  The pickup roller 32 contacts the uppermost document on the document tray 31 and is rotated to feed the uppermost document one by one toward the separation roller 33. The pickup roller 32 starts feeding the next document after a predetermined time between sheets has passed after feeding the trailing edge of the document.

  The separation roller 33 sends out the documents fed from the pickup roller 32 one by one toward the conveyance roller 34. The transport roller 34 feeds the documents transported from the separation roller 33 one by one toward the registration roller 35. The registration roller 35 sends the conveyed document to the first reading position 211a at a predetermined timing.

  The reading guide 36 is disposed on the downstream side of the registration roller 35 so as to face the contact glass 210 of the image reading unit 2. The reading guide 36 is long in the document width direction (main scanning direction), and is biased toward the contact glass 210 by a biasing force of a coil spring (not shown) provided at both ends in the length direction, for example. Is done. The lower surface of the reading guide 36 is formed such that both end portions in the length direction (direction perpendicular to the paper surface of FIG. 2) protrude below the center portion. When the document transport unit 3 is in the closed posture, both end portions in the length direction are in contact with the upper surface of the contact glass 210. The document is configured to pass through a certain gap formed between the central portion in the length direction of the lower surface of the reading guide 36 and the contact glass 210. In this way, in the ADF reading mode, when the document passes between the reading guide 36 and the automatic document reading glass 211, the image formed on the document surface is read.

  The transport roller 37 is disposed downstream of the first reading position 211a in the document transport direction, and transports the document read at the first reading position 211a to the discharge roller 38. The discharge roller 38 discharges the document transported from the transport roller 37 to the document discharge tray 39. The document discharge tray 39 is positioned below the discharge roller 38 in the vicinity of the discharge roller 38 and can stack the discharged document.

  The document transport unit 3 also functions as a “document presser” that presses a document placed on the contact glass 210. The document transport unit 3 is rotatably supported by the image reading unit 2 by, for example, a hinge unit (not shown) disposed on the back side of the image forming apparatus 100 (the back side of the paper surface in FIGS. 1 and 2). . The document transport unit 3 can take a closed posture that covers the contact glass 210 and an open posture that exposes the contact glass 210 by rotating about the hinge portion. Here, the document transport unit 3 also functions as a cover that covers the first reading position 211a and the second reading position 213 so as to be freely opened and closed, and therefore corresponds to an example of a “first cover”. In the flat bed reading mode, the document transport unit 3 is set in the open posture, the document is placed on the document placement glass 212, and then the document transport unit 3 is closed. Then, the document placed on the document placement glass 212 is pressed, and the image formed on the document is read by the operation of the operation panel 4 by the user.

  Next, the first sensor S1, the second sensor S2, and the third sensor S3 will be described. For example, as shown in FIG. 2, the first sensor S <b> 1 is disposed on the lower surface of the contact glass 210, and mainly detects opening / closing of the document transport unit 3. However, the first sensor S <b> 1 is disposed at a position that does not affect the reading operation of the image of the document placed on the document placement glass 212 by the image reading unit 2. For example, the document placement glass 212 is disposed on the front side (or back side) of FIG.

  Specifically, the first sensor S1 outputs ON when satisfying the first condition that both the document transport unit 3 and the opening / closing cover C2 are closed, and when the first condition is not satisfied. Outputs off. Here, since the specific structure of 1st sensor S1 is described in Unexamined-Japanese-Patent No. 2011-153007, the description is abbreviate | omitted here, for example.

  The open / close cover C2 is opened when a jam occurs in the transport path, but is normally used in a closed position. Therefore, assuming that the open / close cover C2 is in the closed position, the first sensor S1 outputs ON when the document transport unit 3 is closed, and turns OFF when the document transport unit 3 is open. Output. Therefore, the opening / closing of the document conveying unit 3 can be detected by the output of the first sensor S1.

  For example, as shown in FIG. 2, the second sensor S <b> 2 is disposed at the downstream end of the document tray 31 in the document conveyance direction, and mainly detects whether or not a document is placed on the document tray 31. . Specifically, the second sensor S2 outputs OFF when no document is placed on the document tray 31 and the second condition that the open / close cover C2 is closed is satisfied. The second sensor S2 outputs ON when the second condition is not satisfied.

  Here, the second sensor S2 can be specifically configured as follows, for example. The second sensor S2 has a configuration in which the second sensor S2 is mechanically turned on when the opening / closing cover C2 is opened, in addition to a normal sensor for detecting whether or not a document is placed. . The configuration in which the second sensor S2 is mechanically turned on when the opening / closing cover C2 is opened is that the second sensor S2 is mechanically turned on via a link mechanism or the like in conjunction with the movement of the opening / closing cover C2. To.

  The open / close cover C2 is opened when a jam occurs in the transport path, but is normally used in a closed position. Therefore, assuming that the opening / closing cover C2 is in the closed position, the second sensor S2 outputs OFF when no document is placed on the document tray 31, and the document is placed on the document tray 31. If it is, output ON. Accordingly, it is possible to detect whether or not a document is placed on the document tray 31 based on the output of the second sensor S2.

  For example, as shown in FIG. 2, the third sensor S <b> 3 is arranged on the upstream side in the document conveyance direction with respect to the conveyance roller 34, and the document is mainly in the conveyance path between the separation roller 33 and the conveyance roller 34. Detect if there is any. Specifically, the third sensor S3 is turned off when there is no document in the transport path between the separation roller 33 and the transport roller 34 and the third condition that the open / close cover C2 is closed is satisfied. Is output, and if the third condition is not satisfied, ON is output.

  Here, specifically, the third sensor S3 can be configured as follows, for example. As the third sensor S3, in addition to a normal sensor (jam sensor) for detecting whether or not there is a document in the conveyance path between the separation roller 33 and the conveyance roller 34, when the opening / closing cover C2 is opened. The third sensor S3 is mechanically turned on. The configuration in which the third sensor S3 is mechanically turned on when the opening / closing cover C2 is opened is that the third sensor S3 is mechanically turned on via a link mechanism or the like in conjunction with the movement of the opening / closing cover C2. To.

  The open / close cover C2 is opened when a jam occurs in the transport path, but is normally used in a closed position. Therefore, assuming that the opening / closing cover C2 is in the closed posture, the third sensor S3 outputs OFF when there is no document in the conveyance path between the separation roller 33 and the conveyance roller 34, and the separation roller ON is output when there is a document in the transport path between 33 and the transport roller 34. Therefore, it is possible to detect whether or not there is a document in the transport path between the separation roller 33 and the transport roller 34 based on the output of the third sensor S3.

  Here, the determination unit 51 shown in FIG. 1 will be described with reference to FIGS. 2 and 3. FIG. 3 is a chart showing the relationship between the outputs of the three sensors S1 to S3 shown in FIG. 2 and the determination results. In FIG. 3, outputs X1 to X3 indicate the outputs of the first sensor S1 to the third sensor S3 before the first sensor S1 changes from on to off (when the first sensor S1 is in the on state). Outputs Y1 to Y3 indicate respective outputs of the first sensor S1 to the third sensor S3 after the first sensor S1 changes from on to off (when the first sensor S1 is in the off state). The rightmost column is a determination result of the determination unit 51.

  When the first sensor S1 changes from on to off, the determination unit 51 determines whether the document transport unit 3 and the second document S2 are output based on the outputs X2 and Y2 of the second sensor S2 and the outputs X3 and Y3 of the third sensor S3. The opening / closing posture of the opening / closing cover C2 is determined.

  The determination unit 51 does not change the outputs of the second sensor S2 and the third sensor S3 before and after the first sensor S1 changes from on to off (Y2 = X2 and Y3 = X3), and When the output (X3 and Y3) of the sensor S3 is OFF (in the case of the first line from the top or the sixth line from the top shown in FIG. 3), it is determined that the document transport unit 3 is open. To do.

  The determination unit 51 does not change the outputs of the second sensor S2 and the third sensor S3 before and after the first sensor S1 changes from on to off (Y2 = X2 and Y3 = X3), and When the output (X3 and Y3) of the sensor S3 is off (in the case of the first line from the top or the sixth line from the top shown in FIG. 3), the following determination is further performed. When the output Y2 of the second sensor S2 is off (first line from the top shown in FIG. 3) after the first sensor S1 changes from on to off, the determination unit 51 puts the document on the document tray 31. Is determined not to be placed. In addition, when the output Y2 of the second sensor S2 is on after the first sensor S1 changes from on to off (in the case of the sixth line from the top shown in FIG. 3), the determination unit 51 It is determined that the document is placed on the tray 31.

  In the determination unit 51, the output (X3, Y3) of the third sensor S3 changes from off to on before and after the first sensor S1 changes from on to off, and the first sensor S1 changes from on to off. When the output Y2 of the second sensor S2 is turned on later (in the case of the third line from the bottom or the fourth line from the bottom shown in FIG. 3), it is determined that the opening / closing cover C2 is open.

  The determination unit 51 includes the second sensor S2 before and after the first sensor S1 changes from on to off, and after the output of the third sensor S3 is on and the first sensor S1 changes from on to off. When the output Y2 is ON (in the case of the first line from the bottom or the second line from the bottom shown in FIG. 3), there is a document in the conveyance path between the separation roller 33 and the conveyance roller 34. It is determined that a jam has occurred. The determination unit 51 does not change the outputs of the second sensor S2 and the third sensor S3 before and after the first sensor S1 changes from on to off (Y2 = X2 and Y3 = X3), and Even when the output (X3 and Y3) of the third sensor S3 is ON (in the case of the sixth line from the bottom shown in FIG. 3), the document is placed in the conveyance path between the separation roller 33 and the conveyance roller 34. It is determined that there is a jam (jam has occurred).

  In other cases, the determination unit 51 determines that the sensor is abnormal (see FIG. 3). The determination unit 51 displays the determination result on the touch panel 41. Here, “sensor abnormality” means that at least one of the first sensor S1 to the third sensor S3 is abnormal.

  Next, the operation of the determination unit 51 will be described with reference to FIGS. FIG. 4 is a flowchart showing the operation of the determination unit 51 shown in FIG. FIG. 5 is a flowchart (first half) showing in detail the determination process in step S107 of the flowchart shown in FIG. FIG. 6 is a flowchart (second half) showing in detail the determination process in step S107 of the flowchart shown in FIG. 4 to 6 are all performed by the determination unit 51.

  First, as shown in FIG. 4, the output X2 of the second sensor S2 and the output X3 of the third sensor S3 are stored in the RAM of the control unit 5 shown in FIG. 1 (step S101). Next, it is determined whether or not the output of the first sensor S1 has changed from on to off (step S103). If it is determined that the output of the first sensor S1 has not changed from on to off (NO in step S103), the process returns to step S101, and the processes after step S101 are repeatedly executed.

  When it is determined that the output of the first sensor S1 has changed from on to off (YES in step S103), the output Y2 of the second sensor S2 and the output Y3 of the third sensor S3 are controlled as shown in FIG. The data is stored in the RAM of the unit 5 (step S105). Then, the determination process described with reference to FIGS. 5 and 6 is executed (step S107), the determination result is displayed on the touch panel 41 shown in FIG. 1 (step S109), and the process ends.

  Next, the determination process executed in step S107 of the flowchart shown in FIG. 4 will be described with reference to FIGS. First, as shown in FIG. 5, whether or not the output Y2 of the second sensor S2 matches the output X2 of the second sensor S2, and the output Y3 of the third sensor S3 matches the output X3 of the third sensor S3. Is determined (step S201). If it is determined that the condition that the output Y2 matches the output X2 and the condition that the output Y3 matches the output X3 is not satisfied (NO in step S201), the process proceeds to step S215 shown in FIG.

  When it is determined that the output Y2 matches the output X2 and the output Y3 matches the output X3 (YES in step S201), it is determined whether or not the output Y3 of the third sensor S3 is off ( Step S203). If it is determined that the output Y3 is not OFF (ON) (NO in step S203), a jam has occurred (the document is in the transport path between the separation roller 33 and the transport roller 34 shown in FIG. 2). Is determined (step S205), and the process proceeds to step S109 shown in FIG. If it is determined that the output Y3 is off (YES in step S203), it is determined that the document transport unit 3 is in the open posture (step S207).

  Then, it is determined whether or not the output Y2 of the second sensor S2 is off (step S209). If it is determined that the output Y2 is off (YES in step S209), it is determined that no document is placed on the document tray 31 (step S211), and the process proceeds to step S109 shown in FIG. If it is determined that the output Y2 is not OFF (ON) (NO in step S209), it is determined that a document is placed on the document tray 31 (step S213), and step S109 shown in FIG. 4 is performed. Proceed to

  Next, when it is determined in step S201 shown in FIG. 5 that the condition that the output Y2 matches the output X2 and the condition that the output Y3 matches the output X3 is not satisfied (NO in step S201), FIG. As shown, it is determined whether the output Y2 of the second sensor S2 is on and the output Y3 of the third sensor S3 is on (step S215). If it is determined that the condition that the output Y2 is on and the output Y3 is on is not satisfied (NO in step S215), the sensor is abnormal (the first sensor S1 to the third sensor S3). It is determined that at least one of them is abnormal) (step S219), and the process proceeds to step S109 shown in FIG.

  If it is determined that the output Y2 is on and the output Y3 is on (YES in step S215), it is determined whether or not the output X2 of the second sensor S2 is on (step S217). ). If it is determined that the output X2 is not on (is off) (NO in step S217), the process proceeds to step S223. If it is determined that the output X2 is on (YES in step S217), it is determined whether or not the output X3 of the third sensor S3 is on (step S221).

  If it is determined that the output X3 is ON (YES in step S221), it is determined that a jam has occurred (a document is in the transport path between the separation roller 33 and the transport roller 34 shown in FIG. 2). (Step S225), the process proceeds to Step S109 shown in FIG. If it is determined that the output X3 is not ON (OFF) (NO in step S221), it is determined that the open / close cover C2 is in the open posture (step S227), and the process proceeds to step S109 shown in FIG.

  If NO in step S217, it is determined whether or not the output X3 of the third sensor S3 is on (step S223). If it is determined that the output X3 is on (YES in step S223), it is determined that a jam has occurred (a document is in the transport path between the separation roller 33 and the transport roller 34 shown in FIG. 2). (Step S229), the process proceeds to Step S109 shown in FIG. If it is determined that the output X3 is not ON (OFF) (NO in step S223), it is determined that the opening / closing cover C2 is in the open posture (step S231), and the process proceeds to step S109 shown in FIG.

  In this way, the number of sensors can be reduced with a simple configuration. Hereinafter, this effect will be described. Conventionally, a sensor for detecting whether or not there is a document on the document tray 31, a sensor for detecting opening / closing of the document transport unit 3, a sensor for detecting opening / closing of the opening / closing cover C2, and the separation roller 33 shown in FIG. Four sensors for detecting whether or not there is a document in the conveyance path between the conveyance rollers 34 are arranged. In contrast, in the present invention, all the detection targets of the four sensors are detected using the outputs of the second sensor S2 and the third sensor S3 before and after the output of the first sensor S1 changes from on to off. can do. Therefore, the number of sensors can be reduced from four to three.

  Specifically, before and after the first sensor S1 changes from on to off, the outputs of the second sensor S2 and the third sensor S3 do not change (Y2 = X2 and Y3 = X3), and the third When the output (X3 and Y3) of the sensor S3 is OFF (in the case of the first line from the top or the sixth line from the top shown in FIG. 3), it is determined that the document transport unit 3 is open. can do.

  Also, before and after the first sensor S1 changes from on to off, the outputs of the second sensor S2 and the third sensor S3 do not change (Y2 = X2 and Y3 = X3), and the third sensor S3 When the outputs (X3 and Y3) are off (in the case of the first line from the top or the sixth line from the top shown in FIG. 3), the following determination can be further made. If the output Y2 of the second sensor S2 is off after the first sensor S1 changes from on to off (first line from the top shown in FIG. 3), the document is placed on the document tray 31. It can be determined that there is no. Further, when the output Y2 of the second sensor S2 is on after the first sensor S1 changes from on to off (in the case of the sixth line from the top shown in FIG. 3), the document is placed on the document tray 31. It can be determined that it is placed.

  Also, the output (X3, Y3) of the third sensor S3 changes from off to on before and after the first sensor S1 changes from on to off, and the first sensor S1 changes from on to off. When the output Y2 of the 2-sensor S2 is on (in the case of the third line from the bottom or the fourth line from the bottom shown in FIG. 3), it can be determined that the open / close cover C2 is open.

  In addition, before and after the first sensor S1 changes from ON to OFF, the second sensor X3 outputs (X3, Y3) are ON and the first sensor S1 changes from ON to OFF. When the output Y2 of the sensor S2 is ON (in the case of the first line from the bottom or the second line from the bottom shown in FIG. 3), the document is placed in the conveyance path between the separation roller 33 and the conveyance roller 34. It can be determined that there is jam (occurrence of jam). Also, before and after the first sensor S1 changes from on to off, the outputs of the second sensor S2 and the third sensor S3 do not change (Y2 = X2 and Y3 = X3), and the third sensor S3 Even when the output (X3 and Y3) is on (in the case of the sixth line from the bottom shown in FIG. 3), there is a document in the conveyance path between the separation roller 33 and the conveyance roller 34 (jam is jammed). It is possible to determine that it has occurred.

  Further, in cases other than the above, it can be determined that the sensor is abnormal (see FIG. 3).

  The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof (for example, (1) to (3) shown below). In order to facilitate understanding, the drawings schematically show each component as a main component, and the thickness, length, number, and the like of each component shown in the drawings are different from the actual for convenience of drawing. . Moreover, the shape, dimension, etc. of each component shown by said embodiment are an example, Comprising: It does not specifically limit, A various change is possible in the range which does not deviate substantially from the structure of this invention.

  (1) In this embodiment, the image forming apparatus 100 according to the present invention has been described. However, any apparatus including the image reading unit 2 and the document conveying unit 3 may be used. For example, a scanner having an ADF may be used.

  (2) In the present embodiment, the determination unit 51 opens / closes the document transport unit 3, opens / closes the opening / closing cover C 2, determines whether or not a document is placed on the document tray 31, and between the separation roller 33 and the transport roller 34. In the above description, the determination unit 51 determines whether the document conveyance unit 3 is opened and closed and the opening / closing cover C2 is opened / closed. That's fine.

  (3) In the present embodiment, the case where the first sensor S1 to the third sensor S3 are respectively arranged at the positions shown in FIG. 2 has been described. However, the first sensor S1 to the third sensor S3 are the other sensors. It may be arranged at a position.

  The present invention is applicable to an image reading apparatus that reads an image formed on a recording medium and an image forming apparatus that forms an image on a recording sheet.

100 Image forming apparatus 1 Image forming unit 2 Image reading unit (part of image reading apparatus)
210 contact glass 211 original automatic reading glass 211a first reading position 212 original placing glass 213 second reading position 3 original conveying unit (first cover, automatic conveying unit, part of image reading apparatus)
31 Document Tray 32 Pickup Roller 33 Separation Roller 34 Transport Roller 35 Registration Roller 36 Reading Guide 37 Transport Roller 38 Discharge Roller 39 Document Discharge Tray 4 Operation Panel 5 Control Unit 51 Judgment Unit C2 Open / Close Cover (Second Cover)
S1 1st sensor S2 2nd sensor S3 3rd sensor

Claims (7)

An image reading apparatus for reading an image formed on a document,
An automatic transport unit having a document tray on which the document is placed;
An image reading unit having a first reading position for reading a document conveyed from the automatic conveyance unit and a second reading position for reading an individual document;
A first cover that opens and closes the first reading position and the second reading position;
A second cover that opens and closes a document transport path from the document tray to the first reading position of the image reading unit;
A first sensor that outputs ON when the first condition that both the first cover and the second cover are closed satisfies the first condition, and outputs OFF when the first condition is not satisfied;
When no document is placed on the document tray and the second condition that the second cover is closed is satisfied, OFF is output, and when the second condition is not satisfied, ON is output. A second sensor to output;
If there is no document in the transport path and the third condition that the second cover is closed is satisfied, OFF is output, and if the third condition is not satisfied, ON is output. A sensor,
A determination unit that determines an open / closed state of the first cover and the second cover based on outputs of the second sensor and the third sensor before and after the first sensor changes from on to off; An image reading apparatus comprising: In the case where the output of the second sensor and the third sensor does not change before and after the first sensor changes from on to off, and the output of the third sensor is off, Determining that the first cover is open;
The image reading apparatus according to claim 1. The determination unit is configured such that the outputs of the second sensor and the third sensor do not change before and after the first sensor changes from on to off, the output of the third sensor is off, and the first sensor If the output of the second sensor is off after the sensor changes from on to off, it is determined that no document is placed on the document tray, and the first sensor changes from on to off. Before and after, the outputs of the second sensor and the third sensor do not change, the output of the third sensor is off, and the output of the second sensor after the first sensor changes from on to off There If it is oN, it is determined that the document on the document tray that is placed, an image reading apparatus according to claim 2.   The determination unit may change the output of the third sensor from off to on before and after the first sensor changes from on to off, and the second sensor after the first sensor changes from on to off. 4. The image reading apparatus according to claim 1, wherein when the output of the sensor is on, it is determined that the second cover is open. 5.   The determination unit is configured such that the output of the third sensor is on before and after the first sensor changes from on to off, and the second sensor outputs after the first sensor changes from on to off. The image reading apparatus according to claim 1, wherein when the output is on, it is determined that there is a document in the conveyance path.   In the case where the outputs of the second sensor and the third sensor are not changed before and after the first sensor is changed from ON to OFF, and the output of the third sensor is ON, The image reading apparatus according to claim 1, wherein the image reading apparatus determines that there is a document in the conveyance path. An image forming apparatus for forming an image on a recording paper,
An automatic transport unit having a document tray on which a document is placed;
An image reading unit having a first reading position for reading a document conveyed from the automatic conveyance unit and a second reading position for reading an individual document;
A first cover that opens and closes the first reading position and the second reading position;
A second cover that opens and closes a document transport path from the document tray to the first reading position of the image reading unit;
A first sensor that outputs ON when the first condition that both the first cover and the second cover are closed satisfies the first condition, and outputs OFF when the first condition is not satisfied;
When no document is placed on the document tray and the second condition that the second cover is closed is satisfied, OFF is output, and when the second condition is not satisfied, ON is output. A second sensor to output;
If there is no document in the transport path and the third condition that the second cover is closed is satisfied, OFF is output, and if the third condition is not satisfied, ON is output. A sensor,
A determination unit that determines an open / closed state of the first cover and the second cover based on outputs of the second sensor and the third sensor before and after the first sensor changes from on to off; An image forming apparatus.

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