JP2016090954A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can determine the size of a recording sheet before image formation and print an image according to the size of the recording sheet.SOLUTION: A distance from a paper feed sensor S2 to a timing sensor S1 along a manual paper feed path R2 and a main conveyance path R0 is determined to be W, and a distance from the position of the leading end of a recording sheet P1 to a rear end detection sensor S5 on the manual paper feed tray 85 along a conveyance direction of the manual paper feed tray 85 is determined to be X (X<W). When an empty sensor S4 detects the recording sheet P1 and the rear end detection sensor S5 does not detect the recording sheet P1, an image forming apparatus calculates a conveyance length of the recording sheet P1 on the basis of the leading end and rear end of the recording sheet P1 detected by the paper feed sensor S2.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus that forms an image on a recording sheet and that can perform printing processing according to a plurality of types of recording sheets having different sizes.

  2. Description of the Related Art Conventionally, an image forming apparatus is provided in which a paper feed tray (manual feed tray) on which recording paper can be placed is provided outside the apparatus so as to supply recording paper desired by a user into the apparatus. In addition, a printer that can automatically recognize a standard size recording paper by providing a sensor at a position corresponding to the standard size on the paper feed tray is also widely used. However, in many cases, the manual feed tray is loaded with irregular-size recording paper, and when the irregular-size recording paper is loaded, the user has to input directly.

  On the other hand, an image forming apparatus that can automatically measure recording paper of an irregular size has been proposed (see Patent Documents 1 to 3). The image forming apparatus in Patent Document 1 detects the passing state of the recording paper upstream of the registration roller pair in the transport direction, and measures the length of the recording paper in the transport direction. The image forming apparatus in Patent Document 2 can feed the recording paper by reversing the registration roller pair after detecting the recording paper by the registration sensor provided in the vicinity of the registration roller pair and acquiring the length in the conveyance direction of the recording paper. Return to position. The image forming apparatus in Patent Document 3 detects the rotation of the plate cylinder from the detection of the leading edge of the recording paper to the detection of the trailing edge, and calculates the length in the conveyance direction of the recording paper. When it is large, a warning is displayed.

Japanese Patent No. 2743203 Japanese Patent Laid-Open No. 10-072145 Japanese Patent Laid-Open No. 2005-231254

  However, the image forming apparatus of Patent Document 1 calculates the length in the conveyance direction of the recording paper based on the time taken from the start of the registration roller pair to the detection of the trailing edge of the recording paper by the detection sensor. If the recording paper cannot be reached, the length of the recording paper in the conveyance direction cannot be measured. For this reason, even if an error occurs in the measurement of the length in the conveyance direction of the recording paper, it may be based on a paper jam due to the state of the recording paper or the conveyance path or a paper jam due to the recording paper not being a size that can be conveyed. It is not possible to automatically determine whether the error occurred for any reason.

  In addition, since the image forming layer of Patent Document 2 detects the size of the recording paper and then reversely rotates the registration roller pair to convey the recording paper in the reverse direction, the possibility of causing a paper jam increases. Therefore, it is necessary to design the conveyance path guide so that the recording paper can be fed backward. Further, since the image forming apparatus disclosed in Patent Document 3 is provided with a sensor on the downstream side of the registration roller pair (registration means) to detect the size of the recording paper, the recording paper is simultaneously formed with the image as in the image forming apparatus disclosed in Patent Document 1. Will be measured. As a result, since an image is formed without measuring the recording paper size, it may not be possible to form an image that matches the recording paper size.

  In view of such a problem, an object of the present invention is to provide an image forming apparatus capable of determining a recording paper size before image formation and printing an image corresponding to the recording paper size.

  In order to achieve the above object, an image forming apparatus of the present invention includes a paper feed tray on which recording paper is mounted, a paper feeding mechanism that feeds recording paper on the paper feeding unit one by one, and the paper feeding mechanism. A sheet feeding state detection unit that detects a recording sheet fed through the registration unit, a registration unit that synchronizes the recording sheet conveyance timing and the image formation timing, and forms an image on the recording sheet conveyed through the registration unit. In the image forming apparatus including the image forming unit, the paper feed tray includes a recording paper loading detection unit that detects whether or not the recording paper is loaded on the paper feed tray, and a conveyance tray of the paper feed tray from a most downstream position. A recording paper detection unit that detects whether or not the recording paper is placed at a position separated by a first distance along the transport direction, and a distance between the registration unit and the paper feed state detection unit When the second distance is The first distance is set shorter than the second distance, and the recording paper loading detection unit detects that the recording paper is loaded on the paper feed tray, and the recording paper detection unit detects the recording paper. When there is no detection, the paper feed detection unit detects the leading edge and the trailing edge of the fed recording paper, and based on the detection time of the recording paper leading edge and the trailing edge, the length of the recording paper in the conveyance direction Then, the image forming unit forms an image on the recording sheet based on the calculated conveyance direction length.

  In such an image forming apparatus, when the shortest length that can be conveyed in the apparatus is the third distance, the first distance is set to be longer than the third distance, and the paper feed detection unit detects the first distance. When the recording paper transport direction length calculated based on the result is shorter than the third distance, it may be notified that the recording paper cannot be used.

  At this time, when the recording paper transport direction length calculated based on the detection result of the paper feed detection unit is shorter than the third distance, the recording paper transport is stopped and the recording paper You may alert | report removal.

  Further, when the recording paper is detected by the recording paper detection unit, an input of a length in the conveyance direction of the recording paper is requested, and the image forming unit is based on the input conveyance direction length of the recording paper. May form an image on the recording paper.

In addition, the image reading unit further reads an image from the document,
When the recording paper is detected by the recording paper detection unit, the recording paper is read by the image reading unit to recognize the length in the conveyance direction of the recording paper, and the recognized conveyance direction of the recording paper Based on the length, the image forming unit may form an image on the recording paper.

  According to the present invention, since the length of the recording paper can be recognized before the recording paper reaches the image forming unit, the image forming unit forms an image according to the recording paper size and prints on the recording paper. it can. In addition, if the recording paper length is shorter than the transportable length, the user can be notified that the recording paper is unusable before image formation, so it is possible to prevent paper jamming due to unusable recording paper. In addition, toner contamination in the apparatus due to paper jams can be prevented.

  Furthermore, when it is necessary to transport the recording paper beyond the registration unit in order to measure the transport length, the input of the transport length in the recording paper direction is accepted, so that the transport length of the recording paper can be measured before image formation. Then, the image forming unit can print an image according to the recording paper size on the recording paper. In addition, if it is necessary to transport the recording paper beyond the registration unit in order to measure the transport length, an error will occur on the device side to check the transport length of the recording paper based on the reading operation of the image reading unit. Therefore, the conveyance length can be automatically measured, and the image forming unit can print an image according to the recording paper size on the recording paper.

FIG. 2 is an external perspective view of the image forming apparatus of the present invention. FIG. 2 is a schematic configuration diagram illustrating an internal configuration of the image forming apparatus illustrated in FIG. 1. These are some enlarged views of the conveyance path in FIG. FIG. 5 is a cross-sectional view illustrating a configuration of a manual feed tray. FIG. 4 is a perspective view illustrating a configuration of a manual feed tray. FIG. 6 is a partial cross-sectional view of the manual feed tray showing the configuration of the empty sensor or the trailing edge detection sensor, where (a) shows the state when no recording paper is loaded, and (b) shows the state of the recording paper. The state when there is placement is shown. These are perspective views which show the structure of an empty sensor or a rear end detection sensor, (a) shows a state when no recording paper is placed, and (b) shows a case where recording paper is placed. Indicates the state. FIG. 2 is a block diagram illustrating a configuration of a control unit in the image forming apparatus of FIG. 1. FIG. 2 is a block diagram illustrating a relationship between a control unit and a paper feed control unit in the image forming apparatus of FIG. 1. FIG. 4 is a flowchart showing a recording sheet length detection operation in the image forming apparatus of FIG. 1. FIG. 3 is a diagram showing a display screen on an operation panel in the image forming apparatus of FIG. 1. FIG. 3 is a diagram showing a display screen on an operation panel in the image forming apparatus of FIG. 1.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, when using terms indicating a specific direction or position (for example, “left / right”, “up / down”, etc.) as necessary, the direction orthogonal to the paper surface in FIG. I have to. These terms are used for convenience of explanation, and do not limit the technical scope of the present invention.

  An image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an external perspective view of an image forming apparatus according to the present invention, and FIG. 2 is a schematic diagram illustrating an internal configuration of the image forming apparatus.

  As shown in FIGS. 1 and 2, the image forming apparatus 1 includes an image reading unit 3 that reads an image from a document P2, a paper feed tray (paper feed device) 4 that stores recording paper P1 on which an image is formed, The toner image is transferred to the recording paper P1 fed from the paper feed tray 4. The fixing unit 6 fixes the toner image transferred by the transfer unit 5 to the recording paper P1. The fixing unit 6 fixes the toner image. A paper discharge tray 7 on which the recording paper P1 on which an image is formed is discharged, and an operation panel 9 for receiving an operation on the image forming apparatus 1. In the image forming apparatus 1, an image reading unit 3 is provided on the upper part of the apparatus main body 2, and a transfer unit 5 is provided below the image reading unit 3.

  A paper discharge tray 7 is provided on the upper side of the transfer unit 5 in the apparatus main body 2 to receive the recording paper P1 that has been image-recorded and discharged by the transfer unit 5 and the fixing unit 6, and the paper feed tray 4 However, it is configured to be insertable / removable below the transfer portion 5 in the apparatus main body 2. With this configuration, as will be described later, the recording paper P1 stored in the paper feed tray 4 is fed into the apparatus main body 2 and then transported upward, whereby the upper portion of the paper feed tray 4 is After the image is transferred by the transfer unit 5 disposed in the image and fixed by the fixing unit 6, the image is discharged onto a discharge tray 7 provided in a space (a recessed space) between the image reading unit 3 and the transfer unit 5. Is done.

  The image reading unit 3 provided on the upper part of the apparatus main body 2 includes a scanner unit 31 that reads an image from the document P2, and an automatic document transport unit that is provided on the scanner unit 31 and that transports the document P2 to the scanner unit 31 one by one. (ADF: Auto Document Feeder) 32. An operation panel 9 is provided on the front side (front side) of the apparatus main body 2. Then, the user performs a key operation while looking at the display screen of the operation panel 9 to perform a setting operation for a function selected from the various functions of the image forming apparatus 1 or execute an operation on the image forming apparatus 1. Can be instructed.

  Next, the internal structure of the apparatus main body 2 will be described with reference to FIG. Of the image reading unit 3 in the upper part of the apparatus main body 2, the scanner unit 31 includes a document table 33 having a platen glass (not shown) on the upper surface side, a light source unit 34 that emits light to the document P2, and a document P2. The image sensor 35 that photoelectrically converts the reflected light from the image into image data, the imaging lens 36 that forms an image of the reflected light on the image sensor 35, and the reflected light from the document P2 are sequentially reflected and incident on the imaging lens 36. And a mirror group 37 to be operated. The light source unit 34, the image sensor 35, the imaging lens 36, and the mirror group 37 are provided inside the document table 33, and the light source unit 34 and the mirror group 37 are configured to be movable in the left-right direction with respect to the document table 33. .

  An ADF 32 is provided on the upper surface side of the scanner unit 31 so as to be openable and closable with respect to the document table 33. The ADF 32 also has a function of bringing the document P2 into close contact with the platen glass (not shown) by covering the document P2 on the platen glass (not shown) of the document table 33. The ADF 32 includes a document placement tray 38 and a document discharge tray 39.

  When the image reading unit 3 having such a configuration reads a document P2 on a platen glass (not shown) of the document table 33, light is emitted from the light source unit 34 moving in the right direction (sub-scanning direction) to the document P2. Is done. The reflected light reflected from the document P2 is sequentially reflected by a mirror group 37 that moves in the right direction, like the light source unit 34, enters the imaging lens 36, and forms an image on the image sensor 35. The image sensor 35 performs photoelectric conversion for each pixel according to the intensity of incident light, and generates an image signal (RGB signal) corresponding to the image of the document P2.

  On the other hand, when reading the document P2 placed on the document placement tray 38, the document P2 is transported to the reading position by the document transport mechanism 40 including a plurality of rollers or the like. At this time, the light source unit 34 and the mirror group 37 of the scanner unit 31 are fixed at predetermined positions inside the document table 33. Accordingly, the light source unit 34 irradiates the reading position portion of the document P2 with light, and the reflected light is imaged on the image sensor 35 via the mirror group 37 and the imaging lens 36 of the scanner unit 31. Then, the image sensor 35 converts the image signal (RGB signal) corresponding to the image of the document P2. Thereafter, the document P2 is discharged to the document discharge tray 39.

  The transfer unit 5 that transfers the toner image to the recording paper P1 includes an image forming unit 51 that generates toner images of Y (Yellow), M (Magenta), C (Cyan), and K (Key tone) colors, and an image forming unit. 51, an intermediate transfer belt 53 to which a toner image of each color is transferred from the image forming unit 51 by contacting an exposure unit 52 provided below each of the image forming units 51, an image forming unit 51 of each color arranged in the horizontal direction, and an image forming unit. A primary transfer roller 54 provided at a position facing the upper side with respect to each image forming unit 51 of each color so as to sandwich the unit 51 and the intermediate transfer belt 53, a drive roller 55 for rotating the intermediate transfer belt 53, and A driven roller 56 that rotates when the rotation of the driving roller 55 is transmitted through the intermediate transfer belt 53, a secondary transfer roller 57 that is installed at a position facing the driving roller 55 across the intermediate transfer belt 53, and intermediate transfer And a cleaner unit 58 which is installed in a position facing the driven roller 56 across the belt 53, provided.

  The image forming unit 51 includes a photosensitive drum 61 that is in contact with the outer circumferential surface of the intermediate transfer belt 53, a charger 62 that charges the outer circumferential surface of the photosensitive drum 61 by corona discharge, and a toner that is charged by stirring. A developing unit 63 that adheres to the outer peripheral surface of the drum 61 and a cleaner unit 64 that removes toner remaining on the outer peripheral surface of the photosensitive drum 61 after the toner image is transferred to the intermediate transfer belt 53 are provided. At this time, the photosensitive drum 61 is installed at a position facing the primary transfer roller 54 with the intermediate transfer belt 53 interposed therebetween, and rotates in the clockwise direction in FIG. Around the photosensitive drum 61, a primary transfer roller 54, a cleaner unit 64, a charger 62, an exposure unit 52, and a developing unit 63 are sequentially arranged along the rotation direction of the photosensitive drum 61. Yes.

  Further, the intermediate transfer belt 53 is composed of an endless belt member having conductivity, for example, and is wound around the drive roller 55 and the driven roller 56 without loosening, so that the intermediate transfer belt 53 is rotated according to the rotation of the drive roller 55 as shown in FIG. In the counterclockwise direction. Around the intermediate transfer belt 53, the secondary transfer roller 57, the cleaner unit 58, and the image forming units 51 for each color of YMCK are arranged in order along the rotation direction of the intermediate transfer belt 53.

  Further, the fixing unit 6 that fixes the toner image transferred to the recording paper P1 includes a heater 59 that heats the toner image on the recording paper P1 and fixes the recording paper P1 together with the heater 59. And a pressurizer 60 that pressurizes P1. The transfer unit 5 and the fixing unit 6 constitute an image forming unit that forms an image on the recording paper P1.

  The paper feed mechanism 8 includes a feed roller 81 that feeds the recording paper P1 stored in the paper feed tray 4 from the uppermost layer to the paper feed path R1, a paper feed roller 82 that separates the fed recording paper P1 one by one, and A separating roller pair by the separating roller 83 and a vertical conveying roller pair 84 for vertically conveying the recording paper P1 fed to the paper feeding path R1 to be sent to the main conveying path R0 are provided. When the recording paper P1 in each paper feed tray 4 is fed out from the top layer one by one to the paper feed path R1 by the rotational drive of the corresponding feed roller 81, paper feed roller 82, and paper roller 83, it is It is sent out toward the main transport path R0 by the transport roller pair 84. The main transport path R0 is a main path of the recording paper P1 that passes through the image forming (printing) process.

  A manual feed tray 85 that feeds the recording paper P1 from the outside is provided on one side of the apparatus main body 2 in the left-right direction (right side in the embodiment). The manual feed tray 85 is supplementarily provided separately from the normal paper feed tray 4 in the apparatus main body 2, and is attached to the lateral side of the apparatus main body 2 so as to be openable and closable. ing. The recording paper P1 on the manual feed tray 85 is moved one by one from the top layer to the main transport path R0 via the manual feed path R2 by the rotational driving of the corresponding feed roller 81, paper feed roller 82, and separating roller 83. Sent out.

  The main transport path R0 is provided with a registration roller pair 86 as a transport roller pair for transporting the recording paper P1 to the transfer unit 5. That is, the registration roller pair 86 is disposed on the upstream side of the nip position between the intermediate transfer belt 53 and the secondary transfer roller 57 in the transfer unit 5. The registration roller pair 86 normally transfers the toner image onto the recording paper P1 in the transfer unit 5, and thus the recording paper fed to the main conveyance path R0 in synchronization with the toner image formation timing in the transfer unit 5. P1 is conveyed to the transfer unit 5. That is, the registration roller pair 86 functions as a registration unit that synchronizes the conveyance timing of the recording paper P <b> 1 and the toner image formation timing in the transfer unit 5.

  A discharge roller pair 87 for discharging the printed recording paper P1 is disposed on the downstream side of the fixing unit 6 in the main transport path R0. The printed recording paper P1 is discharged to the paper discharge tray 7 by the rotational drive of the paper discharge roller pair 87. In the present embodiment, the paper discharge roller pair 87 also functions as a reverse roller pair that reverses the recording paper P1 after single-sided printing. That is, by configuring the paper discharge roller pair 87 so as to be able to rotate forward and reverse, the paper discharge roller pair 87 is also used as a reverse roller pair. Accordingly, the recording paper P1 can be discharged out of the image forming apparatus 1 by the forward and reverse rotation of the paper discharge roller pair 87, or returned to the image forming apparatus 1 by switchback (reverse feed).

  In the apparatus main body 2 of the image forming apparatus 1, there is further provided a circulation conveyance path R3 for reversing the recording paper P1 after single-sided printing to perform double-sided printing, and a plurality of sets are provided in the circulation conveyance path R3. A duplex conveying roller pair 88 is provided. The upstream side of the circulation transport path R3 branches off from between the fixing unit 6 and the paper discharge roller pair 87 in the main transport path R0. The downstream side of the circulation conveyance path R3 joins the upstream side of the transfer unit 5. In the circulation conveyance unit R3, the recording paper P1 after single-sided printing is reversed by the paper discharge roller pair 87, and is conveyed again to the main conveyance path R0 via the circulation conveyance path R3 by the rotational drive of the double-side conveyance roller pair 88.

  As shown in FIGS. 2 and 3, the recording paper P <b> 1 fed from the paper feed tray 4 is fed to the downstream side in the transport direction of the paper feed roller 82 and the separating roller 83 in the paper feed path R <b> 1 for each of the paper feed trays 4. A paper feed sensor (paper feed state detector) S1 for detection is provided. Similarly, in the manual paper feed path R2 with respect to the manual feed tray 85, a paper feed sensor (paper feed state) that detects the recording paper P1 fed from the manual feed tray 85 on the downstream side in the transport direction of the paper feed roller 82 and the separating roller 83. Detection unit) S2 is provided. Further, a registration sensor (conveyance state detection unit) S3 for detecting the recording paper P1 is provided on the upstream side of the registration roller pair 86 in the conveyance direction.

  Each of the sheet feeding sensors S1, S2 and the registration sensor S3 is configured by, for example, a reflective optical sensor. At this time, the paper feed sensors S1, S2 and the registration sensor S3 emit light from their installation positions toward the paper feed paths R1, R2 or the main transport path R0, and reflect light from the recording paper P1 being transported. When the light is received, the passage of the recording paper P1 is detected and a detection signal indicating the passage position of the recording paper P1 is output.

  Paper feed sensors S1 and S2 detect the leading and trailing edges of the recording paper P1 fed from the paper feed tray 4 or the manual feed tray 85, respectively. Accordingly, the control unit 10 described later can check the paper feed state (conveyance state) of the recording paper P1 and calculate the length of the recording paper P1 in the conveyance direction based on the detection signals of the paper feed sensors S1 and S2. . Further, the registration sensor S3 detects the leading edge of the recording paper P1 that passes the position immediately upstream of the registration roller pair 86 on the main transport path R0. As a result, the control unit 10 to be described later temporarily stops the registration roller pair 86 until the recording paper P1 is conveyed at the transfer timing in the transfer unit 5 based on the detection signal from the registration sensor S3. The conveyance can be made to wait.

  As shown in FIG. 4, the manual feed tray 85 is provided auxiliary to one side of the apparatus main body 2 separately from the normal paper feed tray 4 in the apparatus main body 2. It is attached to one side of 2 so that it can be opened and closed. The manual feed tray 85 is configured to open and close up and down about a pair of pivot pin shafts 513 that connect the front end side and one side portion of the apparatus main body 2. As shown in FIGS. 4 and 5, the manual feed tray 85 includes a push-up plate 514 that pushes up the leading end side of the recording paper P1 placed on the tray main body 511, and the recording paper P1 before feeding as a center reference. A pair of side guide plates 515 and the like are provided.

  The push-up plate 514 is disposed on the downstream side of the tray body 511 in the transport direction, and is pivotally supported by the manual feed tray 85 via the pivot support shaft 516 on the base end side so as to be vertically rotatable. The push-up plate 514 is configured to rotate upward by a transmission mechanism (not shown) only during printing and return to the original position when printing is completed. The transmission mechanism for rotating the push-up plate 514 up and down may be a mechanism using a spring, a mechanism using a combination of a cam member and a drive motor, or a mechanism using a combination of a drive motor and a gear member. It may be. Although detailed illustration is omitted, the pair of side guide plates 515 are configured to move in close proximity to each other in the left-right width direction. By sandwiching the recording paper P1 on the manual feed tray 85 from both sides in the left-right width direction by the pair of side guide plates 515, the recording paper P1 on the manual feed tray 85 is set to the center reference regardless of the standard.

  As shown in FIGS. 3 to 5, the manual feed tray 85 detects an empty sensor (recording paper mounting detection unit) S <b> 4 that detects whether or not the recording paper P <b> 1 is placed, and the trailing edge of the recording paper P <b> 1. A rear end detection sensor (recording paper detection unit) S5 is provided in the tray body 511. On the tray main body 511, the empty sensor S4 is disposed in the vicinity of the boundary position with the push-up plate 514, and the rear end detection sensor S5 is disposed on the downstream side in the transport direction from the empty sensor S4. The empty sensor S4 and the trailing edge detection sensor S5 are configured by touch sensors that detect the contact with the recording paper P1, as will be described later.

  The relationship between the conveyance path from the manual feed tray 84 and the sensor position will be described with reference to FIG. As shown in FIG. 4, the distance from the paper feed sensor S2 to the timing sensor S1 along the manual paper feed path R2 and the main transport path R0 (hereinafter referred to as “distance between sensors on the transport path”) is W. Then, along the conveyance direction of the manual feed tray 85, the distance from the front end position of the recording paper P1 (the front end of the push-up plate 514) to the rear end detection sensor S5 in the manual feed tray 85 (hereinafter referred to as “tray front end / sensor distance”). Let X be X. At this time, the rear end detection sensor S5 is arranged so that the distance W between the sensors on the conveyance path is longer than the distance X between the front end of the tray and the sensor.

  Further, the distance X between the front end of the tray and the sensor is the shortest recording sheet that is the shortest recording sheet that can be transported in the main transport path R0, the sheet feed path R1, the manual feed path R2, and the circulation transport path R3. It is set longer than the length Y. The shortest recording paper length Y is recorded on each of the paper feed roller 82, the vertical conveyance roller pair 84, the registration roller pair 86, the secondary transfer roller 57, the fixing unit 6, the paper discharge roller pair 84, and the double-side conveyance roller pair 87. It is determined by the nip position of the paper P1. That is, the shortest recording paper length Y is set to a distance shorter than the longest distance between adjacent nips in the main conveyance path R0, the sheet feeding path R1, the manual sheet feeding path R2, and the circulation conveyance path R3.

  As shown in FIG. 5, the empty sensor S <b> 4 and the rear end detection sensor S <b> 5 are provided in the tray main body 511 at positions corresponding to the through holes 540 on the surface of the tray main body 511, and recording is performed by entering and exiting the through holes 540. The paper P1 is detected. As shown in FIGS. 6 and 7, the empty sensor S4 and the rear end detection sensor S5 include a pair of bearing bodies 542, 543, a shaft body 544 supported by the bearing bodies 542, 543, and a shaft body 544. A recording paper detection plate 545, a sensor lever 546, a torsion spring 549 wound around a shaft body 544, and a position detection sensor 550 that detects the position of the sensor lever 546 are provided.

  The bearing bodies 542 and 543 are fixed to the tray main body 511 and arranged so as to face each other along the feeding direction (conveying direction) of the recording paper P1. Here, the bearing body 542 is disposed on the upstream side in the feeding direction, and the bearing body 543 is disposed on the downstream side in the feeding direction. Each of the bearing bodies 542 and 543 has a through hole at the center, and is supported by inserting a shaft body 544 into the through hole.

  The recording paper detection plate 545 and the sensor lever 546 are sequentially arranged from the bearing body 542 side upstream in the feeding direction of the recording paper P1, and are configured to rotate integrally with the shaft body 544, respectively. The recording paper detection plate 545 and the sensor lever 546 are arranged on the other side with the central axis of the shaft body 544 in plan view. Accordingly, when the recording paper detection plate 545 rotates upward, for example, the sensor lever 546 rotates downward.

  The torsion spring 549 is provided on the bearing body 543 side of the shaft body 544 and biases the shaft body 544 so that the recording paper detection plate 545 rotates upward. The position detection sensor 550 is disposed on the side where the sensor lever 546 is located with respect to the central axis of the shaft body 544, and detects the position of the sensor lever 546. The position detection sensor 550 optically detects, for example, whether or not the sensor lever 546 is at a predetermined position, and may be constituted by a transmission type sensor using a light emitting / receiving element.

  The recording paper detection plate 545 rotates between an upper end position shown in FIGS. 6A and 7A and a lower end position shown in FIGS. 6B and 7B. When the recording paper detection plate 545 is at the upper end position, the recording paper detection plate 545 protrudes above the through hole 540 on the recording material placement surface of the tray body 511. Further, when the recording paper detection plate 545 is at the lower end position, the recording paper detection plate 545 is configured to be below the through hole 540 on the recording paper placement surface of the tray body 511. The recording paper detection plate 545 is biased by the torsion spring 549 so as to rotate upward together with the shaft body 544. In addition, when the recording paper detection plate 545 is at the upper end position, the sensor lever 546 is detected by the position detection sensor 550 (detection result ON) as shown in FIG. When the detection plate 545 is at the lower end position, as shown in FIG. 7B, the detection plate 545 rotates downward to reach a position where it is not detected by the position detection sensor 550 (detection result OFF).

  The image forming apparatus 1 includes a control unit 10 configured as shown in FIG. 8, and each unit constituting the image forming apparatus 1 is controlled by the control unit 10 to perform a printing operation on a recording sheet, an image reading operation from a document, and the like. Various operations are performed. The control unit 10 includes a CPU (Central Processing Unit) 101 that executes various arithmetic processes and controls, a ROM (Read Only Memory) 102 that stores control programs, and a RAM (Random Access) that temporarily stores arithmetic data. Memory) 103, an image processing unit 104 that generates image data that is a basis of the toner image formed by the transfer unit 5, an image memory 105 that temporarily stores the image data obtained by the image processing unit 104, and an image An input / output interface 106 that transmits and receives signals to and from each unit constituting the forming apparatus 1 and a transfer operation setting unit 107 that sets the number of times of transfer and a transfer voltage based on the type of recording paper are provided.

  When the control unit 10 configured as described above receives a signal corresponding to the operation received by the operation panel 9, the CPU 101 recognizes an operation based on the operation received by the operation panel 9. Similarly, when the control unit 10 receives a signal transmitted from an external terminal or the like via a communication network 110 such as a LAN (Local Area Network) by the input / output interface 106, the control unit 10 recognizes an operation designated by the external terminal. . Thereby, the CPU 101 reads a control program based on an operation designated via the operation panel 9 or the external terminal from the ROM 102, and the CPU 101 operates based on the control program.

  The control unit 10 gives control signals to the image reading control unit 113, the paper feed control unit 114, the conveyance control unit 115, the exposure control unit 116, the transfer control unit 117, and the fixing control unit 118. Receive signals and image signals. The image reading control unit 113 controls each unit of the image reading unit 3 to execute an image reading operation on the document P2, and transmits an image signal based on the read image to the control unit 10. The paper feed controller 114 feeds the recording paper P <b> 1 from the paper feed tray 4 or the manual feed tray 85 by driving the feeding roller 81, the paper feed roller 82, and the separation roller 83. The conveyance control unit 115 drives the recording roller pair 86, the paper discharge roller pair 87, and the double-sided conveyance roller pair 88 to convey the recording paper P1 in each of the main conveyance path R0 and the circulation conveyance path R3.

  The exposure control unit 116 controls the exposure unit 52 based on the image data from the control unit 10, and irradiates the photosensitive drum 61 of the image forming unit 51 of each color of Y, M, C, and K with each laser beam. An electrostatic latent image corresponding to each color image of Y, M, C, and K is formed on the photosensitive drum 61. The transfer control unit 117 performs primary transfer onto the intermediate transfer belt 53 by controlling the image forming unit 51 of each color of Y, M, C, and K, the primary transfer roller 54, the driving roller 55, and the secondary transfer roller 57. The transferred toner image is secondarily transferred to the recording paper P1. The fixing control unit 118 drives the heater 59 and the pressurizer 60 to heat and heat the toner image on the recording paper P1 passing through the fixing nip by the heater 59 and the pressurizer 60 to fix it.

  As shown in FIG. 9, the paper feed control unit 114 receives signals from the paper feed sensors S <b> 1 and S <b> 2 and controls the control unit 10 to feed the recording paper P <b> 1 from the paper feed tray 4 or the manual feed tray 85. Notification to the unit 10. Further, the paper feed control unit 114 receives signals from the empty sensors S41 and S4, and notifies the control unit 10 of whether or not the recording paper P1 is mounted on the paper feed tray 4 or the manual feed tray 85. The empty sensor S41 installed in the paper feed tray 4 has the same configuration as the empty sensor S4 of the manual feed tray 85 described above, and protrudes from the bottom surface of the paper feed tray 4 to determine whether or not the recording paper P1 is mounted. To detect.

  The paper feed control unit 114 drives and controls the paper feed motors 143 and 144 via the motor control units 141 and 142. Further, the paper feed controller 114 selectively engages the clutches 145 to 148 to selectively control the feeding roller 81 and the paper feed roller 82 of the paper feed tray 4 and the manual feed tray 85, respectively. Each of the clutches 145 to 148 is a well-known one-way clutch that transmits power only in one rotation direction, and when the paper feed motors 143 and 144 are rotated forward (rotation direction according to the recording paper conveyance direction). While the rotational force is transmitted to the rotation shafts of the corresponding rollers 81 and 82, when the paper feed motors 143 and 144 are stopped or reversely rotated, they rotate idly.

  When feeding the recording paper P <b> 1 from the paper feed tray 4, the paper feed control unit 114 rotates the paper feed motor 143 via the motor control unit 141. Then, when the clutch 145 is connected and the feeding roller 81 is rotated so that the uppermost recording paper P1 placed on the paper feed tray 4 is sent out toward the paper feed path R1, the clutch 146 is connected to feed the paper. The roller 82 is rotated, and the double feeding of the recording paper P1 is prevented by the paper feed roller 82 and the separating roller 83. Similarly, when feeding the recording paper P <b> 1 from the manual feed tray 85, the paper feed control unit 114 rotates the paper feed motor 144 via the motor control unit 142. When the clutch 147 is connected and the feeding roller 81 is rotated to feed the uppermost recording paper P1 placed on the manual feed tray 85 toward the manual paper feed path R2, the clutch 148 is connected to feed the paper. The roller 82 is rotated.

  The control unit 10 receives signals from the paper feed sensor S2, the empty sensor S4, and the trailing edge detection sensor S5 via the paper feed control unit 114, and the length of the recording paper P1 mounted on the manual feed tray 85 ( Recognize the length along the transport direction). Further, a recording paper width detection sensor S6 for detecting the position of the side guide plate 515 is provided in the manual feed tray 85, and the control unit 10 detects a detection signal from the recording paper width detection sensor S6 via the paper feed control unit 114. In response, the width of the recording paper P1 (width orthogonal to the transport direction) is recognized. Note that the recording paper width detection sensor S6 includes, for example, a variable resistor whose resistance value changes according to the position of the side guide plate 515 that slides in the left-right width direction.

  As a result, the image forming apparatus 1 recognizes in the control unit 10 whether the recording paper P1 loaded on the manual feed tray 85 is a standard size or an irregular size, and an image that matches the size of the recording paper P1. Data can be generated and an image can be optimally formed on the recording paper P1. Hereinafter, the operation of the image forming apparatus 1 when the manual feed tray 85 is used will be described below with reference to the flowchart shown in FIG.

  The paper feed controller 114 checks whether or not the recording paper P1 is placed on the manual feed tray 85 based on the signal from the empty sensor S4 (STEP 1). Upon receiving a signal indicating that the detection result is OFF from the position detection sensor 550 (see FIGS. 6 and 7) of the empty sensor S4, the paper feed control unit 114 determines that the recording paper P1 is mounted on the manual feed tray 85. Upon confirming that the recording paper P1 is loaded on the manual feed tray 85 (Yes in STEP1), the paper feed control unit 114 receives the detection signal from the recording paper width detection sensor S6 and calculates the width Pw of the recording paper P1. (STEP2).

  The control unit 10 communicates with the recording paper control unit 114, acquires the width PW of the recording paper P1 placed on the manual feed tray 85, searches for a standard size having the same width as the width PW of the recording paper P1, The searched standard size is displayed on the operation panel 9 (SETP3). At this time, a button display as shown in FIG. 11 is displayed on the operation panel 9 so that a plurality of regular sizes and irregular sizes based on the search result can be selected. In the example of FIG. 11, the control unit 10 receives from the recording paper control unit 114 that the width (paper width) PW of the recording paper P1 on the manual feed tray 85 is 297 mm, and performs “A4 portrait placement” and “A3 landscape placement”. ]. Buttons 911 to 913 are displayed on the operation panel 9 so that any one of “undefined” can be selected. If the standard size cannot be retrieved from the width PW of the recording paper P1, the operation panel 9 displays that it is an irregular size.

  Then, the control unit 10 confirms whether or not the recording paper P1 on the manual feed tray 85 has a standard size based on the user operation received through the operation panel 9 (STEP 4). In STEP 3, if the standard size cannot be retrieved, the control unit 10 automatically recognizes that the recording paper P1 has an irregular size. When the standard size is designated by the user (YES in STEP 4), the control unit 10 feeds the recording paper P1 from the manual feed tray 85 through the recording paper control unit 114 (STEP 5), and then executes an image forming process described later. (STEP 6).

  When the recording paper P1 on the manual feed tray 85 has an irregular size (NO in STEP 4), the paper feed control unit 114 receives a signal from the rear end detection sensor S5 and receives the signal of the length of the recording paper P1 on the manual feed tray 85. The length PL is compared with the tray tip / sensor distance X (STEP 7). When the trailing edge of the recording paper P1 on the manual feed tray 85 is positioned upstream in the feeding direction from the trailing edge detection sensor S5, the paper feed control unit 114 detects the position detection sensor 550 of the empty sensor S4 (see FIGS. 6 and 7). ) Receives a signal indicating that the detection result is OFF. At this time, the paper feed control unit 114 determines that the length PL of the recording paper P1 is longer than the tray tip / sensor distance X (YES in STEP 7), and the control unit 10 causes the operation panel 9 to record the recording paper P1. The display for acquiring the length PL of is executed (STEP 8).

  In STEP 8, the operation panel 9 causes the image reading unit 3 to read an image of the recording paper P1 to obtain the length (paper length) PL of the recording paper P1, as shown in FIG. 12, for example. , “Load paper in the scanner” is displayed. When the user places the recording paper P1 on the ADF 32 or the document table 33 and operates the set button 921 on the operation panel 9 based on the display on the operation panel 9 (Yes in STEP 9), the control unit 10 reads the image. The image reading unit 3 is driven through the control unit 113, the image of the recording paper P1 is read (STEP 10), and the length PL of the recording paper P1 is acquired (STEP 11). At this time, the acquired length PL of the recording paper P1 is displayed in an area 923 on the operation panel 9 shown in FIG.

  In STEP 8, as shown in the example of FIG. 12, on the operation panel 9, “enter the paper length” so that the user can directly input the length (paper length) PL of the recording paper P1. Simultaneously with the display, a key 922 for numerical input is displayed. When the user operates the numerical input key 922 based on the display on the operation panel 9 and inputs the length PL of the recording paper P1 (No in STEP9), the control unit 10 determines the length PL of the recording paper P1. Is acquired (STEP 11). As described above, after the length PL of the recording paper P1 is acquired in STEP11, the process proceeds to STEP5 and image formation is performed on the recording paper P1 fed from the manual feed tray 85 (STEP6).

  When the trailing edge of the recording paper P1 on the manual feed tray 85 is located downstream in the feeding direction from the trailing edge detection sensor S5, the paper feed control unit 114 detects the position detection sensor 550 of the empty sensor S4 (see FIGS. 6 and 7). ) Receives a signal indicating that the detection result is ON. At this time, the paper feed control unit 114 determines that the length PL of the recording paper P1 is shorter than the tray tip / sensor distance X (YES in STEP 7), and the control unit 10 feeds paper to the paper feed control unit 114. A control signal is given to start the operation (STEP 12).

  Upon receiving a control signal for starting a paper feeding operation from the controller 10, the paper feed controller 114 drives the paper feed motor 144 via the motor controller 142, and then connects the clutches 147 and 148 at a predetermined timing. The feed roller 81 and the paper feed roller 82 are driven to rotate. As a result, the uppermost recording paper P1 on the manual feed tray 85 is fed to the manual feed path R2. When the leading edge of the recording paper P1 fed to the manual feed path R2 passes the detection position of the paper feeding sensor S2, the paper feeding control unit 114 receives the detection signal of the paper feeding sensor S2 and passes the leading edge of the recording paper P1. The timing is stored (STEP 13). After that, when the trailing edge of the recording paper P1 passing through the manual feed path R2 passes the detection position of the paper feed sensor S2, the paper feed control unit 114 receives the detection signal of the paper feed sensor S2, and after the recording paper P1 The end passage timing is stored (STEP 14).

  The paper feed control unit 114 calculates the passage time of the recording paper P1 from the passage timings of the front and rear ends of the recording paper P1 stored in STEP 13 and STEP 14, respectively, and based on the transport speed based on the rotational speed of the paper feed roller 82. Thus, the length PL of the recording paper P1 is acquired and notified to the control unit 10 (STEP 15). The control unit 10 compares the length PL of the recording paper P1 received from the paper feed control unit 114 with the shortest recording paper length Y, and determines whether or not the recording paper P1 on the manual feed tray 85 can be conveyed. (STEP 16).

  When the length PL of the recording paper P1 is longer than the shortest recording paper length Y (YES in STEP 16), the control unit 10 performs image formation on the recording paper P1 fed from the manual feed tray 85 (STEP 6). On the other hand, when the length PL of the recording paper P1 is equal to or shorter than the shortest recording paper length Y (NO in STEP 16), the control unit 10 transmits a control signal to the paper feed control unit 114 and the conveyance control unit 115, The conveying operation of the recording paper P1 is stopped (STEP 17). Thereafter, the control unit 10 causes the operation panel 9 to display a screen (JAM processing screen) that prompts the user to remove the recording paper P1 remaining in the manual paper feed path R2 and the main transport path R0 (STEP 18). At this time, for example, on the operation panel 9, “paper in the manual feed tray cannot be used. Remove the paper from inside the device. A JAM processing screen with a character notation such as “” is displayed to prompt the user to remove the recording paper P1.

  An image forming operation by the image forming apparatus 1 in STEP 6 will be briefly described. The image forming apparatus 1 receives a start signal, an image signal, and the like and starts a printing operation. When the printing operation starts, the recording paper P1 fed out from the paper feed tray 4 or the manual feed tray 85 is transported to the image forming unit 5 along the main transport path R0. When the recording paper P1 conveyed to the main conveyance path R0 is detected by the registration sensor S3, the conveyance control unit 114 receives the signal from the registration sensor SE and stops the registration roller pair 86 after a predetermined time has elapsed. Thus, the conveyance of the recording paper P1 is stopped, and the leading edge of the recording paper P1 is positioned upstream of the transfer nip (secondary transfer roller 57 position) in the transfer unit 5 in the conveyance direction.

  The control unit 10 generates an image signal for image formation by the image processing unit 104 based on the width PW and the length PL of the recording paper P1 conveyed to the main conveyance path R0 and stores the image signal in the image memory 105. The control unit 10 transmits image data of each color of Y, M, C, and K based on the image signal stored in the image memory 105 to the exposure control unit 114 and drives the transfer unit 5 through the transfer control unit 115. The transfer unit 5 transfers an image to the recording paper P1 based on a color electrophotographic method, and adopts an intermediate transfer method using an intermediate transfer belt 53 as an image transfer method to the recording paper P1.

  At this time, in the transfer unit 5, the Y, M, C, and K color image forming unit 51 irradiates the surface of the photosensitive drum 61 charged by the charger 62 with laser light from the exposure unit 52. An electrostatic latent image corresponding to each color image is formed. The toner charged by the developing device 63 is transferred to the surface of the photosensitive drum 61 on which the electrostatic latent image is formed, and a toner image is formed on the photosensitive drum 61. The toner image carried on the surface of the photosensitive drum 61 is transferred to the intermediate transfer belt 53 by the electrostatic force of the primary transfer roller 54 when coming into contact with the intermediate transfer belt 53. In addition, a toner image in which the colors Y, M, C, and K are overlapped is formed. On the other hand, the untransferred toner remaining on the photosensitive drum 61 having the toner image transferred to the intermediate transfer belt 53 is scraped off by the cleaner unit 64 and removed from the photosensitive drum 61.

  The toner image transferred to the intermediate transfer belt 53 is moved to a transfer position where the toner image is in contact with the secondary transfer roller 57 as the intermediate transfer belt 53 is rotated by the driving roller 55 and the driven roller 56. At this time, in order to transfer the toner image on the intermediate transfer belt 53 to the recording paper P1, the transfer unit 5 starts the operation, and then the conveyance control unit 114 rotates the registration roller pair 86 so that the toner image on the main conveyance path R0. The conveyance of the recording paper P1 is resumed. Then, the recording paper P1 conveyed to the transfer position on the main conveyance path R0 reaches the transfer nip sandwiched between the intermediate transfer belt 53 and the secondary transfer roller 57, and the toner image on the intermediate transfer belt 53 is transferred. Transcribed. Untransferred toner remaining on the intermediate transfer belt 53 that has transferred the toner image onto the recording paper P 1 is scraped off by the cleaner unit 58 and removed from the intermediate transfer belt 53. In addition, the recording paper P1 onto which the toner image has been transferred at the contact position with the secondary transfer roller 57 is conveyed to the fixing unit 6 controlled by the fixing control unit 118.

  When the recording paper P1 on which the unfixed toner image is placed on one side passes through the fixing position of the fixing unit 6, the recording paper P1 is heated by the heater 59 and pressurized by the pressurizer 60, and the unfixed toner image is applied to the paper surface. It is fixed. In the case of single-sided printing, the recording paper P1 after toner image fixing (after single-sided printing) is discharged to the paper discharge tray 7 by the paper discharge roller pair 87. On the other hand, in the case of duplex printing, the above-described image forming operation is performed again by conveying the recording paper P1 after single-sided printing to the circulation conveyance path R3 for duplex printing, turning it over, and returning it to the main conveyance path R0 again. Then, the toner image is transferred and fixed on the other surface of the recording paper P1 passing through the transfer unit 5 and the fixing unit 6 and then discharged onto the paper discharge tray 7.

  The image forming apparatus according to the present invention has been described by taking an electrophotographic image forming apparatus as an example. However, the image forming apparatus is not limited to the electrophotographic system, and may be an image forming apparatus using another system such as an ink jet system. . The image forming apparatus according to the present invention may be an MFP (Multifunction Peripheral) having a copy function, a scanner function, a printer function, and a fax function, or may be a printer, a copier, a facsimile, or the like. In addition, the structure of each part is not limited to embodiment of illustration, A various change is possible in the range which does not deviate from the meaning of this invention.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Apparatus main body 3 Image reading part 4 Paper feeder 5 Transfer part 6 Fixing part 7 Paper discharge tray 8 Paper feed mechanism 9 Operation panel 10 Control part 31 Scanner part 32 ADF
33 Document Plate 34 Light Source 35 Image Sensor 36 Imaging Lens 37 Mirror Group 38 Document Placement Tray 39 Document Ejection Tray 40 Document Conveying Mechanism 51 Image Forming Unit 52 Exposure Unit 53 Intermediate Transfer Belt 54 Primary Transfer Roller 55 Drive Roller 56 Followed Roller 57 Secondary Transfer Roller 58 Cleaner 59 Heater 60 Pressurizer 61 Photosensitive Drum 62 Charger 63 Developer 64 Cleaner 81 Feed Roller 82 Feed Roller 83 Rolling Roller 84 Vertical Transport Roller Pair 85 Manual Tray 86 Register Roller Pair 87 Paper discharge roller pair 88 Double-sided conveyance roller pair P1 Recording paper P2 Document R0 Main transport path R1 Paper feed path R2 Manual paper feed path R3 Circulation paper feed path S1, S2 Paper feed sensor S3 Registration sensor S4 Empty sensor S5 Rear edge detection center Sensor S6 Recording paper width detection sensor 101 CPU
102 ROM
103 RAM
DESCRIPTION OF SYMBOLS 104 Image processing part 105 Image memory 106 Input-output interface 110 Communication network 113 Image reading control part 114 Paper feed control part 115 Conveyance control part 116 Exposure control part 117 Transfer control part 118 Fixing control part 141,142 Motor control part 143,144 Supply Paper motors 145 to 148 Clutch 511 Tray body 513 Pivot pin shaft 514 Push-up plate 515 Side guide plate 540 Through hole 542, 543 Bearing body 544 Shaft body 545 Recording paper detection plate 546 Sensor lever 549 Torsion spring 550 Position detection sensor

Claims (5)

A paper feed tray on which recording paper is mounted, a paper feed mechanism that feeds recording paper on the paper feed unit one by one, a paper feed state detection unit that detects recording paper fed through the paper feed mechanism, An image forming apparatus comprising: a registration unit that synchronizes the recording sheet conveyance timing and the image formation timing; and an image forming unit that forms an image on the recording sheet conveyed through the registration unit.
The paper feed tray is separated from the recording paper loading detection unit for detecting whether or not the recording paper is loaded on the paper feed tray by a first distance along the transport direction from the most downstream position in the transport direction of the paper feed tray. A recording paper detection unit for detecting whether or not the recording paper is placed at a position;
When the distance between the registration unit and the paper feed state detection unit is a second distance,
The first distance is set shorter than the second distance, and the recording paper loading detection unit detects that the recording paper is loaded on the paper feed tray, and the recording paper detection unit detects the recording paper. If there is no detection
The paper feed detection unit detects the leading edge and the trailing edge of the fed recording paper, calculates the conveyance direction length of the recording paper based on the detection time of the recording paper leading edge and trailing edge, and then calculates An image forming apparatus, wherein the image forming unit forms an image on the recording sheet based on the length in the transport direction. When the shortest length that can be conveyed in the apparatus is the third distance, the first distance is set longer than the third distance,
When the recording paper transport direction length calculated based on the detection result of the paper feed detection unit is shorter than the third distance, it is notified that the recording paper cannot be used. The image forming apparatus according to claim 1.   When the recording paper transport direction length calculated based on the detection result of the paper feed detection unit is shorter than the third distance, the recording paper transport is stopped and the recording paper removal is notified. The image forming apparatus according to claim 2.   When the recording paper is detected by the recording paper detection unit, the recording paper detection unit requests input of the length of the recording paper in the conveyance direction, and the image forming unit performs the input based on the input conveyance direction length of the recording paper. The image forming apparatus according to claim 1, wherein an image is formed on a recording sheet. An image reading unit for reading an image from a document;
When the recording paper is detected by the recording paper detection unit, the recording paper is read by the image reading unit to recognize the length in the conveyance direction of the recording paper, and the recognized conveyance direction of the recording paper The image forming apparatus according to claim 1, wherein the image forming unit forms an image on the recording sheet based on a length.

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