JP4083655B2 - Document feeder - Google Patents

Description

  The present invention relates to a document feeding device that is used in an image forming apparatus such as a copying machine and transports a document to a document reading position.

  In general, an image forming apparatus includes a document feeding device that separates a large number of documents (document bundle) one by one and feeds (conveys) them to an image reading position such as a scanner device. Such a document feeder is provided with a document feed tray on which documents are stacked (set), and the document set on the document feed tray is sent to an image reading position by a document transport mechanism, where the document After reading, the document is discharged to the document discharge tray.

  Also, in a paper feeding device that feeds recording paper to the image forming unit via the paper transport path, the recording paper is separated one by one from the paper tray on which the recording paper is stacked, and then passed through the paper transport path. The image is fed to the image forming unit.

  In a document feeding device or a paper feeding device, it is necessary to separate and transport the document or the recording paper one by one, regardless of the amount of the document or the recording paper. Guide pins are planted outward in a direction perpendicular to the paper feeding direction on the side surface of the bottom plate on which recording paper is stacked, and a vertical guide groove is provided in the bottom plate guide of the paper feeding cassette corresponding to the guide pins, A guide pin is inserted into the guide groove, a compression spring is engaged between the bottom plate and the paper feed cassette to urge the bottom plate upward, and the bottom plate is raised while maintaining a horizontal state. As a result, the angle of contact with the inclined surface of the inclined member of the sheet fed by the sheet feeding roller loaded on the bottom plate is always kept constant regardless of the amount of the sheet, and the separation performance is stabilized. (See Patent Document 1).

  Furthermore, in the document feeder, when the document is set in the document feed tray, the bottom plate portion of the document feed tray is raised and the document reaches the position where the document can be fed, and then feeding of the document is started. For example, in a copying machine, when a copy button (copy button) is operated after a document or a bundle of documents is set in a document feed tray, the bottom plate of the document feed tray is raised so that the document can be fed. After reaching the position, the document is fed to the document reading position.

  As described above, even when the copy button is operated, the original feeding operation is not started until the original reaches the original feedable position, and as a result, the time from the setting of the original to the start of copying is delayed. A first operation mode for raising the bottom plate portion of the document feed tray immediately after the document is set on the document feed tray in order to shorten the time from setting the document to the start of copying (image formation start); There is a second operation mode in which the first and second operation modes can be selected by providing a second operation mode in which the bottom plate is raised when the copy button is operated after the set is detected (see Patent Document 2).

JP 2002-274663 A (paragraphs (0017) to (0022), FIGS. 1 to 4) JP 11-237770 A (paragraph (0022) to paragraph (0025), FIGS. 4 to 6)

  However, in Patent Document 1, although the angle of contact with the inclined surface of the inclined member of the sheet fed by the sheet feeding roller is always kept constant regardless of the amount of the sheet, the bottom plate itself is maintained in a horizontal state. When the entire bottom plate is raised, the bottom plate receives the full load of the sheet, resulting in a large drive mechanism such as a biasing means when the entire bottom plate is raised. There is.

  Further, in Patent Document 2, when the first operation mode is selected, the bottom plate portion of the document feed tray rises to the document feedable position immediately after the document set is set, but the document is set. There is a problem that it is necessary for the user to select an operation mode before, and it takes time to start image formation.

  Therefore, in view of the problems of the prior art, the present invention can stably feed a document with a simple configuration regardless of the number of documents loaded on the document feed tray, and sets the document on the document feed tray. It is an object of the present invention to provide a document feeder capable of shortening the time until the start of subsequent image formation.

In order to solve such problems, the present invention provides a document stacking unit on which documents are stacked, and a document feeding mechanism that feeds documents one by one from the document stacking unit in a predetermined transport direction. In the document feeder including the device housing that supports the document stacking unit, the document stacking unit is positioned on the downstream side in the transport direction and on the upstream side in the transport direction. It is separated into the second stacking portion, wherein the first stacking portion is supported in the device housing to be movable in the vertical direction, and a drive mechanism for moving the first stacking portion to the vertical direction, before Symbol Control means for driving the drive mechanism to move the first stacking portion upward to position the uppermost original at a position where the original can be fed with respect to the original feeding mechanism; and A bridge that communicates with the second loading section; The upstream end in the transport direction of the first stacking unit is supported at the downstream end in the transport direction so as to be rotatable about an axis extending in the width direction of the first stacking unit, and the upstream end in the transport direction of the bridge portion is It is in contact with the upper surface of the second stacking unit .

(Delete)

  Further, in the present invention, a speed selection unit that selects a rising speed of the first stacking unit is provided, and the control unit controls the rising speed of the first stacking unit with the rising speed selected by the speed selecting unit. You may make it do.

  In the present invention, it is used in an image forming apparatus that forms an image according to image data obtained by reading the document, and the image is formed after the first stacking unit reaches the document feedable position. When the image forming mode is selected, the control unit starts feeding the document, and when the lowering mode is selected after the first stacking unit reaches the document feeding available position, the control unit The means performs a return control for returning the first stacking unit from the document feedable position to the initial position, and then releases the first stacking unit again to the document feedable position when the lowering mode is released. Control to raise. It is preferable that a descent mode selection unit for selecting and canceling the descent mode is provided, and the descent mode selection unit is disposed on the surface of the apparatus housing.

In the present invention, a document stacking unit on which documents are stacked, a document feeding mechanism that feeds documents one by one from the document stacking unit in a predetermined transport direction, and an apparatus housing that supports the document stacking unit The document stacking unit is separated into a first stacking unit located on the downstream side in the transport direction and a second stacking unit located on the upstream side in the transport direction, The first stacking unit is supported by the apparatus housing so as to be movable in the vertical direction, and a driving mechanism for moving the first stacking unit in the vertical direction, and driving the drive mechanism to control the first stacking unit. And a control means for positioning the uppermost document at a position where the document can be fed with respect to the document feeding mechanism, and the first stacking unit has reached the document feedable position. Whether the first stacking unit is at the document feedable position. Then comprises a position detecting means for sending the arrival detection signal, the control means stops the first rise of the loading unit from the start and do not receive the arrival detection signal within a predefined time the drive mechanism Then, after stopping the drive mechanism, the drive mechanism is controlled to lower the first stacking portion to an initial position, and when the load applied to the drive mechanism exceeds a predetermined load You may make it provide the load reduction means to reduce the load concerning the said drive mechanism.

In the present invention, there is provided a document stacking height detection unit that detects a stacking height of the document stacked on the document stacking unit and sends a document stacking height detection signal, and the control unit detects the document stacking height detection signal. The rising speed of the first stacking unit is determined based on the first stacking unit, and the control means determines the first stacking unit as the document stacking height indicated by the document stacking height detection signal increases. Decrease the ascending speed set value . A speed variable selection section for selecting cancellation of the speed variable control, and when the speed variable control is canceled by the speed variable selection section, the control means cancels the speed variable control. Also good.

  As described above, the document feeder of the present invention separates the document stacking unit into the first stacking unit located downstream in the transport direction and the second stacking unit positioned upstream in the transport direction. The first stacking unit is supported by the apparatus housing so as to be movable in the vertical direction, and when the loading of the document on the document stacking unit is detected, the first stacking unit is moved upward to the uppermost position. Since the positioned original is positioned at the position where the original can be fed with respect to the original feeding mechanism, when the uppermost original is positioned at the position where the original can be fed, the original stacking unit that applies the entire original load is driven. Therefore, there is an effect that the original can be moved up and down with a small driving source. As a result, the sheet can be stably fed regardless of the number of sheets stacked on the sheet stacking tray with a simple configuration and at a low cost, and immediately after the document is set, the first stacking unit Is raised to a position where the document can be fed, so that the time from when the document is set to when image formation is started can be shortened.

  In the sheet feeding device of the present invention, the bridging portion that connects the first and second stacking units is connected to the downstream end of the first stacking unit at the downstream end of the first stacking unit. Since the upstream end of the bridging portion in the conveyance direction is in contact with the upper surface of the second stacking portion, the first stacking portion is moved when the sheet is conveyed. Even if it moves in the vertical direction, the bridging portion rotates around the fulcrum axis in accordance with the movement of the first stacking unit, so that the sheet conveyance from the sheet stacking unit is not hindered.

  According to the present invention, when an image forming mode for image formation is selected after the first stacking unit reaches the document feedable position, document feeding is started, and the first stacking unit starts to feed the document. When the lowering mode is selected after reaching the feedable position, the first stacking unit is returned from the document feedable position to the initial position when the lowering mode is canceled. Since it has been raised to the feedable position, it can be easily handled even if it is desired to add a document after it has been stacked on the document stacking unit. It can be loaded on the loading section.

  In the present invention, if the document feeding ready position is not reached within a predetermined time after the first stack unit starts to rise, the drive mechanism is stopped and then the drive mechanism is controlled to control the first stack. Since the portion is lowered to the initial position, an excessive load is not applied to the drive mechanism for a long time, and the failure and breakage of the tray drive mechanism can be prevented beforehand.

  In the present invention, the rising speed of the first stacking unit is determined according to the document stacking height, and when the document stacking height is low, the rising speed of the first stacking unit is increased. In this case, the time required for document feeding can be shortened.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  First, referring to FIG. 1, an illustrated document feeder 10 is used together with an image forming apparatus (for example, a copying machine), and is arranged on the upper surface side of a main body of an image forming apparatus (not shown). The document feeder 10 includes a document feed tray (document stacking unit) 11 and a document feed mechanism 12, and a bundle of documents is stacked on the document feed tray 11. The document feeding mechanism 12 separates the documents one by one from the bundle of documents stacked on the document feeding tray 11, and conveys the documents to the first image reading position GP1.

  Then, after an image on one side of the original is read by the first scanner unit (not shown) at the first image reading position GP1, the original is sent to the second original reading position GP2, and then the second image reading position GP1. The document on the other side of the document is read by the scanner unit 13. Then, the original is discharged to the original discharge tray 15 disposed below the original feed tray 11 by the discharge roller pair 16.

  The illustrated document feeder 10 is compatible with double-sided printing. When single-sided printing is performed, for example, an image on a document is read only at the first image reading position GP1. Although not shown, in the image forming apparatus, an image carrier such as a photosensitive drum is exposed based on image data obtained by reading a document, and an electrostatic latent image is formed on the image carrier. . Then, after the electrostatic latent image is developed by the developing device, the toner image on the image carrier is transferred to the recording paper, the toner image on the recording paper is fixed, and the paper is discharged onto a paper discharge tray.

  As shown in FIG. 1, the document feeding mechanism 12 is disposed on the rear side (downstream in the document transport direction) of the document feeding tray 11, and the document feeding mechanism 12 includes a document feeding roller unit (hereinafter simply referred to as “sheet feeding roller unit”). The document feed roller unit 14 includes a roller housing 14a, a pickup roller (pickup roller) 14b, a feed mechanism 14c, and a separation roller 14d.

  The feed mechanism 14 c includes a pair of feed rollers (feed rollers) 141, a feed belt 142 is stretched around the feed rollers 141, and a separation roller 14 d is in contact with the feed belt 142. The pickup roller 14b and the feed mechanism 14c are housed in a roller housing 14a, and the separation roller 14d is provided on the base side of the document feeding mechanism 12. Instead of the above-described feed mechanism 14c, a single feed roller 141 may be provided, and the feed roller 141 may be disposed to face the separation roller 14d.

  As illustrated, the document feed tray 11 includes a first tray unit (first stacking unit) 11a located on the document feeding mechanism 12 side (that is, downstream in the document transport direction) and an upstream side in the document transport direction. And a second tray portion (second stacking portion) 11b, which is rotated to an automatic document feeder housing (hereinafter simply referred to as a device housing) 21. It is installed as possible.

  The first tray section 11a is attached to the apparatus casing 21 so as to be movable in the vertical direction in the figure (the direction indicated by the solid line arrow in the figure) with respect to the apparatus casing 21. A bridging portion 11c is attached to the upstream end in the direction so as to be rotatable about a fulcrum shaft 22 extending in the width direction of the apparatus housing 21, and a portion of the bridging portion 11c on the upstream side in the document conveying direction is It is in contact with the upper surface of the second tray portion 11b.

  As shown in the drawing, the second tray portion 11b forms an inclined surface 11d whose upper surface is inclined obliquely downward at the downstream side in the document conveying direction, and the document of the bridging portion 11c is formed on the inclined surface 11d. The upstream portion in the conveyance direction is in contact. A document guide 23 for defining the document width is provided on the upper surface of the first tray unit 11a. The first tray unit 11a is fixedly attached to the document feeding mechanism 12, and the first tray unit 11a The downstream end in the document transport direction is located downstream of the pickup roller 14b.

  The first tray portion 11a is driven upward from the reference position (initial position) shown in FIG. When the first tray portion 11a is at the reference position, as shown in FIG. 1, the lower surface of the bridging portion 11c is in contact with the inclined surface 11d, and the first tray portion 11a It is located below the second tray portion 11b.

  Now, referring also to FIG. 2, when a bundle of documents is stacked (set) on the document feed tray 11, a document set is detected by a document set detection sensor (document stack detection means) 31 (not shown in FIG. 1). The document set detection sensor 31 turns on a document set detection signal (that is, sends a document set detection signal to the controller 32). When the document set detection signal is turned on, the controller (control means) 32 controls the tray driving mechanism 24 to drive the first tray portion 11a by the tray driving mechanism 24, and the first tray portion 11a is initialized. Raise from position.

  When the document at the uppermost position contacts the pickup roller 14b, the pickup roller 14b is pressed upward, and when the pressing of the pickup roller 14b is detected by the document position detection sensor 33 (not shown in FIG. 1) (that is, the document) The position detection sensor 33 detects the document at the highest position), and the controller stops the tray driving device 24 so that the document at the highest position is in contact with the pickup roller 14b (the highest position). The state in which the original at the position is in contact with the pickup roller 14b is hereinafter referred to as an original feedable position).

  In this way, when the document is set on the document feed tray 11, the first tray portion 11a is immediately driven from the initial position to the document feedable position, and the first tray portion 11a at the document feedable position. Is in a standby state. When the copy button (copy button) 35 of the image forming apparatus is operated, the controller 32 drives the document feeding mechanism 12 to start the document feeding operation. The document is picked up by the pickup roller 14b, and the separation roller. Only one of the originals picked up by the pickup roller 14b is separated by 14d, and is sent downstream by the feed mechanism 14c.

  As shown in FIG. 1, the document feeding mechanism 12 has a document feeding section 20 disposed on the downstream side of the feed mechanism 14c. The document feeding section 20 includes a large-diameter driving roller 25 and a small-diameter driving roller 25. The driven rollers 26 and 27 are provided, and the peripheral surfaces of the driven rollers 26 and 27 are in contact with the peripheral surface of the drive roller 25. Then, the document is sent to the first document reading position GP1 by the document feeding section 20, and then passes through the second document reading position GP2 and is discharged to the document discharge tray 15.

  As the document is fed, the number of documents on the document feed tray 11 decreases. As described above, the document position detection sensor 33 detects the uppermost document on the document feed tray 11, and this In accordance with the detection result, the controller 32 controls the tray driving mechanism 24 to always position the uppermost document at the same position with respect to the pickup roller 14b (that is, the uppermost document is positioned at a document feedable position). ). At this time, the bridging portion 11c rotates around the fulcrum shaft 22 in the direction indicated by the dashed arrow (clockwise) as the first tray portion 11a rises, as if the bridging portion 11c is upstream in the document conveyance direction. It will turn as if it is a fulcrum.

  FIG. 3 shows the position of the first tray portion 11a in a state where all the documents on the document feed tray 11 are fed. In this state, the upper surface of the first tray portion 11a is the pickup roller 14b. It will be in the state close to. When all the documents are fed, the document set detection sensor 31 turns off the document set detection signal. Accordingly, the controller 32 controls the tray driving mechanism 24 to move the first tray portion 11a downward and return it to the reference position (initial position).

  As shown in FIG. 3, the tray drive mechanism 24 described above has a rotating shaft body 24a extending in the width direction of the apparatus housing 21 and a driving stay portion 24b having one end attached to the rotating shaft body 24a. The stay portion 24b extends in the document transport direction along the lower surface of the first tray portion 11a. When the rotary shaft body 24a is rotationally driven, the drive stay portion 24b rotates about the rotary shaft body 24a, and thereby the first tray portion 11a moves upward. Further, the tray driving mechanism 24 has a guide portion 241, and the first tray portion 11 a is guided in the vertical direction by the guide portion 241. Specifically, the guide unit 241 includes a rack 24c and a pinion 24d, the pinion 24d is disposed on the lower surface of the first tray unit 11a, and the rack 24c is disposed on the apparatus housing 21 side. 24c and the pinion 24d are meshed.

  When the rotating shaft body 24a is rotated forward, the first tray portion 11a moves upward by the rotation of the drive stay portion 24b. At this time, the first tray portion 11a moves upward while being guided by the rack 24c and the pinion 24d. On the other hand, when the rotary shaft body 24a is rotationally driven in the reverse direction, the first tray portion 11a moves downward by the rotation of the drive stay portion 24b. Also at this time, the first tray portion 11a moves downward while being guided by the rack 24c and the pinion 24d.

  As described above, the document feed tray 11 includes the first tray portion 11a positioned on the document feeding mechanism 12 side (downstream side in the document transport direction) and the second tray portion 11b positioned on the upstream side in the document transport direction. In other words, only the first tray portion 11a is moved in the vertical direction in accordance with the number of documents, and the uppermost document end is brought into contact with the pickup roller 14b. Considering that it is applied to the entire first and second tray portions 11a and 11b, the load applied to the first tray portion 11a is reduced, and a drive source for driving the first tray portion 11a is reduced accordingly. It can be downsized.

  Further, a bridging portion that is rotatable around a fulcrum shaft provided at the upstream end in the document transport direction of the first tray portion 11a is disposed between the first tray portion 11a and the second tray portion 11b. Therefore, even if the first tray portion 11a is driven in the vertical direction, the communication with the first and second tray portions 11a and 11b is maintained well, and document feeding is not hindered. .

  When the document is set on the document feed tray 11, the first tray unit 11a is immediately driven from the initial position to the document feedable position, and waits for the first tray unit 11a at the document feedable position. Therefore, if the copy button or the like is operated, the document reading is immediately started and the image formation is executed. As a result, it is possible to shorten the time until the image formation is started after the document is set on the document feed tray. .

  It should be noted that a speed selection button (speed selection section) 34 (FIG. 2) for selecting the rising speed of the first tray section 11a is provided on the operation panel (not shown) of the image forming apparatus, and a first selection is made by the user. You may enable it to select the raising speed of tray part 11a. For example, when one rising speed is selected from several speed settings by the speed selection button 34, the controller 32 raises the first tray unit 11a according to the selected speed. In this way, the user can arbitrarily set the rising speed of the first tray portion 11a, and can select a speed according to the user.

  A second embodiment of the document feeder according to the present invention will be described with reference to FIG. The document feeder in the second embodiment has the same components as those described in FIG. 1, and the controller 32 described in FIG. 2 has a function different from that in the first embodiment.

  As described in the first embodiment, when a document is set on the document feed tray 11 (step S1), the raising control of the first tray unit 11a is started, and the controller 32 moves the first tray unit 11a. The position is raised from the reference position (initial position) (step S2). When the first tray portion 11a reaches the document feedable position, the first tray portion 11a enters a standby state at that position.

  As described above, the operation panel of the image forming apparatus is provided with the copy button 35 (indicated by a broken line block in FIG. 2). Here, the operation panel further includes an up / down operation button (down mode selection unit: FIG. 2). 36 (shown by a broken line block) is provided, and when the copy button 35 is operated, the controller 32 shifts to the normal mode (copy mode (image forming mode)). On the other hand, when the up / down operation button 36 is operated, the controller 32 shifts to the document addition mode (descent mode). That is, when the mode is selected by the copy button 35 and the lift operation button 36 (step S3), and the copy button 35 is operated, the controller 32 enters the normal mode (step S4), as described in the first embodiment. Thus, document feeding from the document feeding tray 11 to the document reading position is started and image formation is performed.

  On the other hand, when the up / down operation button 36 is operated in step S3, the controller 32 enters the document addition mode (step S5), and controls the tray driving mechanism 24 to lower the first tray 11a to the initial position. That is, when it is desired to add a document after the document is once stacked, if the elevating operation button 36 is operated, the first tray portion 11a returns from the document feedable position to the initial position. Then, when the user adds the original and then operates the up / down operation button 36 again, the original addition mode is canceled (step S6), and the controller 32 returns to step S2 to control the tray driving device 24 to control the first. The tray unit 11a is raised from the initial position to the document feedable position.

  It should be noted that the above-described lifting operation button 36 may be provided on the surface of the apparatus housing 21. In this way, the mode switching operation is facilitated when it is desired to add a document after setting the document. .

  In this way, it is possible to easily cope with the case where it is desired to add a document after the document is set on the document feed tray 11, and when the number of documents is very large, the document is divided into the document feed tray 11. Can be set.

  Referring to FIGS. 1 and 2 again, as described in the first embodiment, when the document is set on the document feeding tray 11, the first tray portion 11a is immediately moved from the initial position to the document feedable position. However, for example, a foreign object may be caught and the rise of the first tray 11a may stop. In such a state, a large load is applied to the tray driving mechanism 24, and the tray driving mechanism 24 may break down or be damaged.

  For this reason, here, when the controller 32 starts to raise the first tray unit 11a, the controller 32 drives a built-in timer (not shown) to start measuring time, that is, when the built-in timer times a predetermined time (that is, If the first tray portion 11a does not reach the position where the document can be fed at the time when the built-in timer is counted up (that is, if no detection signal is received from the document position detection sensor (position detection means) 33), the tray The operation of the drive mechanism 24 is temporarily stopped, the tray drive mechanism 24 is reversed, and the first tray portion 11a is returned to the initial position.

  In this way, an excessive load is not applied to the tray drive mechanism 24 for a long time, and failure / breakage of the tray drive mechanism 24 can be prevented beforehand.

  Here, referring to FIG. 5, the tray drive mechanism 24 described above has a drive source (motor) 41, and the motor 41 is fixed to the position of the support frame body 42. The shaft of the motor 41 passes through the support frame body 42, and a gear 43 is attached to the shaft of the motor 41. A gear 44 is rotatably disposed on the support frame body 42, and the gear 44 meshes with the gear 43.

  At the center of the gear 43, the rotary shaft body 24a described above is mounted, and a torque limiter (load reducing means) 45 is mounted on the rotary shaft body 24a (in FIG. 5, the rotary shaft body 24a A part is omitted, and the rotary shaft body 24a is connected to another rotary shaft body 47 through a gear group 46). A pair of flange portions 42 a are formed in the support frame body 42, and the support frame body 42 is attached to the side surface of the apparatus housing 21 by these flange portions 42 a. At this time, the support frame 42 is attached to the apparatus casing 21 so that the motor 41 is positioned outside the apparatus casing 21, and the rotary shaft 24 a extends into the apparatus casing 21.

  Now, when the motor 41 is driven, the rotary shaft body 24a is driven to rotate, and as described above, the drive stay portion 24b (FIG. 1) rotates about the rotary shaft body 24a as a fulcrum. The tray portion 11a moves up and down.

  As described above, when the rising of the first tray 11a stops due to a foreign object or the like being sandwiched, an excessive load is applied to the motor 41, but the torque limiter 45 is mounted on the rotary shaft body 24a. Therefore, when the torque applied to the rotating shaft body 24a exceeds a predetermined torque value (set torque) set by the torque limiter 45, the torque applied to the rotating shaft body 24a is limited by the torque limiter 45. As a result, the motor 41 There is no excessive load. That is, as a result of the torque being limited by the torque limiter 45, an excessive load is not applied to the tray drive mechanism 24. Note that the set value of the torque limiter is set, for example, {(motor torque at the time of setting the maximum number of original sheets) + (safety factor)} ≧ torque limiter set value.

  In the above example, the torque applied to the rotating shaft body 24a (that is, the motor 41) is regulated using the torque limiter 45. However, the torque applied to the shaft of the motor 41 is detected by the torque detector, and the torque of the motor shaft is determined. When the set torque is exceeded, the controller 32 may turn off the motor.

  Referring to FIGS. 6 and 7, FIGS. 6 and 7 are simplified views of the document feeder 10 shown in FIG. 1, and FIG. 6 shows a small amount (several sheets) of documents on the document feed tray 11. FIG. 7 shows a state in which a large amount (for example, 200 sheets) of documents are set on the document feed tray 11.

  As shown in FIG. 6, the document set detection sensor 31 described with reference to FIG. 2 is disposed at the front end (upstream end in the document transport direction) of the document feeding mechanism 12, and a document is set on the document feed tray 11. Then, the front end of the document is detected by the document set detection sensor 31, and the first tray portion 11a is driven upward as described above.

  On the other hand, a stack height detection sensor (document stack height detection means) 51 (indicated by a one-dot chain line block in FIG. 2) for detecting the document stack height is disposed on the first tray portion 11a. When a document is set on the document feed tray 11, a stack height detection signal indicating the document stack height is sent from the stack height detection sensor 51 to the controller 32.

  The stack height detection sensor 51 is, for example, a switch group disposed at a predetermined interval along the height direction on the inner surface of the document guide 23. When the document is set on the document feed tray 11, the document height is detected. The switches are sequentially turned on according to the height, but the controller 32 knows the document stacking height according to the on / off state of the switches arranged in the height direction (that is, the switches are turned on in the height direction). The position changed from to off is recognized as the document stacking height).

  The distance from the reflective sensor to the bottom surface of the document feeding tray 11 before the document is set is obtained by using the reflective sensor, and the distance from the reflective sensor to the uppermost document is subsequently obtained after the document is set. Thus, the document stacking height may be obtained according to these distances.

  In the fourth embodiment, the controller 32 shown in FIG. 2 is set with a stacking height-speed table that defines the relationship between the document stacking height and the rising speed setting value of the first tray section 11a. Then, when the document stacking height is obtained, the controller 32 refers to the stacking height-speed table and obtains the rising speed setting value of the first tray unit 11a. Then, the controller 32 controls the tray drive mechanism 24 based on the ascending speed setting value, and raises the first tray portion 11a at the speed indicated by the ascending speed setting value. The other control has been described with reference to FIG.

As shown in FIG. 6, when the number of documents set on the document feed tray 11 is small (when the document stacking height is low), the controller 32 sets the ascending speed setting value to v ₁ mm / sec. As a result, the first tray portion 11a is raised. On the other hand, as shown in FIG. 7, when the number of documents set in the document feed tray 11 is large (when the document stacking height is high), the controller 32 sets the ascending speed setting value to v ₂ mm / sec. As a result, the first tray section 11a is raised (v ₁ > v ₂ ).

  In the stacking height-speed table, as the document stacking height increases, the rising speed setting value may be decreased stepwise, and as the document stacking height increases, the rising speed setting is set. The value may be decreased linearly. In any case, the stacking height-speed table is set so that the time for the first tray unit 11a to rise from the initial position to the document feedable position is substantially constant regardless of the number of documents. Become.

  In addition, as shown by the one-dot chain line block in FIG. 2, when the speed variable selection button (speed variable selection section) 52 is provided on the operation panel of the image forming apparatus and the speed variable selection button 52 is operated, the controller 32 can change the ascent speed. In the release mode, the controller 32 may control the rising speed of the first tray unit to be constant regardless of the document stacking height. When the controller 32 operates the speed variable selection button 52 in the ascending speed variable release mode, the controller 32 enters the ascending speed variable mode, and the first according to the document stacking height as described above. The rising speed of the tray part 11a is changed. The speed variable selection button 52 described above may be provided in the casing of the document feeder 10.

  Further, when the rising speed of the first tray portion 11a is increased, it is desirable to reduce the rising speed immediately before the first tray portion 11a reaches the document feedable position. At this time, the distance between the uppermost document and the pickup roller may be measured by a reflection type sensor or the like provided separately, and decelerated according to the measured distance.

  The document stacking unit is separated into a first stacking unit positioned downstream in the document transport direction and a second stacking unit positioned upstream in the document transport direction, and the first stacking unit is moved up and down. When the loading of the document on the document stacking unit is detected by supporting it in the apparatus housing, the drive mechanism is driven and controlled, and the first stacking unit is moved upward to feed the document at the topmost position. Since the mechanism is positioned at a position where the document can be fed, printing is performed immediately when an image forming button or the like is operated. As a result, printing can be performed in a short time, and an image forming apparatus such as a copying machine can be used. Applicable.

FIG. 3 is a cross-sectional view illustrating an example of a document feeding device according to the present invention in a state where a first tray portion is in an initial position. It is a block diagram which shows an example of the control system of the document feeder by this invention. FIG. 3 is a cross-sectional view illustrating an example of a document feeding device according to the present invention in a state where a first tray portion is at a maximum raised position. 6 is a flowchart for explaining an example of document elevation control of the document feeder according to the present invention. It is a perspective view which shows an example of the drive system of the document feeder by this invention with a torque limiter. FIG. 3 is a diagram schematically illustrating a state in which a small amount (several sheets) of originals are set on the original feeding device according to the present invention. FIG. 3 is a diagram schematically illustrating a state in which a large amount of originals are set on an original feeding device according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Document feeder 11 Document feed tray 12 Document feed mechanism 13 Second scanner unit 14 Document feed roller section 15 Document discharge tray 16 Discharge roller pair 11a First tray section 11b Second tray section 11c Bridge portion 11d Inclined surface 21 Device housing 22 Support shaft 24 Tray drive mechanism 31 Document set detection sensor 32 Controller 33 Document position detection sensor 34 Speed selection button 35 Copy button 36 Lifting operation button 45 Torque limiter 51 Document stacking height detection sensor

Claims (9)

A document feeding unit comprising a document stacking unit on which documents are stacked, a document feeding mechanism that feeds documents one by one from the document stacking unit in a predetermined transport direction, and an apparatus housing that supports the document stacking unit. In the device
The document stacking unit is separated into a first stacking unit located on the downstream side in the transport direction and a second stacking unit located on the upstream side in the transport direction,
The first stacking unit is supported by the apparatus housing so as to be movable in the vertical direction,
A drive mechanism for moving the first stacking unit in the up-down direction ;
And control means to position the document at the top is moved upward to the front SL drive mechanism controls and drives the first stacking portion to the original feed can position with respect to the document feeding mechanism,
A bridging portion connecting the first and second loading portions;
The bridging portion is supported at the downstream end in the transport direction so as to be rotatable around an axis extending in the width direction of the first stacking portion at the upstream end in the transport direction of the first stacking portion.
The document feeding apparatus according to claim 1, wherein an upstream end of the bridge portion in the conveyance direction is in contact with an upper surface of the second stacking portion . A speed selection unit that selects a rising speed of the first stacking unit; and the control unit controls the rising speed of the first stacking unit with the rising speed selected by the speed selection unit. The document feeder according to claim 1, wherein: An image forming mode that is used in an image forming apparatus that forms an image according to image data obtained by reading the original and that forms an image after the first stacking unit reaches the original feedable position. 2. The document feeding apparatus according to claim 1, wherein the control means starts feeding the document when is selected . Used in an image forming apparatus that forms an image according to image data obtained by reading the original, and when the first stacking unit reaches the original feedable position and the lowering mode is selected, The control means performs a return control for returning the first stacking unit from the original document feedable position to the initial position, and then the first stacking unit can be fed again when the lowering mode is released. 2. The document feeder according to claim 1, wherein control for raising the position is performed . 5. The document feeding apparatus according to claim 4, further comprising a lowering mode selection unit for selecting and canceling the lowering mode, wherein the lowering mode selection unit is disposed on a surface of the apparatus housing . A document feeding unit comprising a document stacking unit on which documents are stacked, a document feeding mechanism that feeds documents one by one from the document stacking unit in a predetermined transport direction, and an apparatus housing that supports the document stacking unit. In the device
The document stacking unit is separated into a first stacking unit located downstream in the transport direction and a second stacking unit positioned upstream in the transport direction,
The first stacking unit is supported by the apparatus housing so as to be movable in the vertical direction,
A drive mechanism for moving the first stacking unit in the up-down direction;
Control means for driving the drive mechanism to move the first stacking portion upward to position the uppermost original at a position where the original can be fed with respect to the original feeding mechanism;
Position detecting means for detecting whether or not the first stacking unit has reached the document feedable position and sending an arrival detection signal when the first stacking unit reaches the document feedable position. The control means stops the drive mechanism if it does not receive the arrival detection signal within a predetermined time after starting to raise the first stacking unit,
After stopping the driving mechanism, the document feeding apparatus is characterized in that the driving mechanism is controlled to lower the first stacking unit to an initial position . 7. The document feeding device according to claim 6, further comprising load reducing means for reducing a load applied to the drive mechanism when a load applied to the drive mechanism exceeds a predetermined load. A document feeding unit comprising a document stacking unit on which documents are stacked, a document feeding mechanism that feeds documents one by one from the document stacking unit in a predetermined transport direction, and an apparatus housing that supports the document stacking unit. In the device
The document stacking unit is separated into a first stacking unit located on the downstream side in the transport direction and a second stacking unit located on the upstream side in the transport direction,
The first stacking unit is supported by the apparatus housing so as to be movable in the vertical direction,
A drive mechanism for moving the first stacking unit in the up-down direction;
Control means for driving the drive mechanism to move the first stacking portion upward to position the uppermost original at a position where the original can be fed with respect to the original feeding mechanism;
A document stacking height detection means for detecting a stacking height of the document stacked on the document stacking unit and sending a document stacking height detection signal;
The control means determines the rising speed of the first stacking unit based on the document stacking height detection signal, and sets the rising speed setting value of the first stacking unit as the document stacking height increases. A document feeding device characterized in that variable speed control is performed to reduce the size . A speed variable selection section that selects cancellation of the speed variable control is provided, and when the speed variable control is canceled by the speed variable selection section, the control means cancels the speed variable control. The document feeder according to claim 8 .

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