JP2010150034A - Image recorder - Google Patents

Abstract

An image recording apparatus including a mechanical mechanism having a simple configuration capable of stably supplying paper P is provided.
Regardless of the amount of paper P stored in the paper feed tray 3, the transport path length from the rear edge of the paper P in contact with the rear guide member 40 to the paper sensor 31 is made substantially constant. As described above, the rear guide surface 41 of the rear guide member 40 is configured to be positioned on the upstream side in the transport direction as the stacking height of the paper P increases, and the upstream side in the transport direction when the paper feed roller 30a rotates in the reverse direction. The rear edge of the sheet P that moves to the rear is brought into contact with the rear guide surface 41.
[Selection] Figure 6

Description

  The present invention relates to a printer having a paper feed mechanism that can maintain a constant conveyance path length for conveying a sheet to a predetermined position regardless of the amount of accumulated sheets (also referred to as cut sheets or paper) stored in a paper feed tray. The present invention relates to image recording apparatuses such as copying machines and facsimile machines.

  2. Description of the Related Art Conventionally, in image recording apparatuses such as printers, copiers, and facsimile machines, as in Patent Document 1 and Patent Document 2, a paper feed tray whose upper surface is opened at the bottom of a housing (apparatus housing) is arranged in a substantially horizontal direction. A configuration is known that can be inserted and removed. A tilt separating plate is provided on the downstream side in the insertion direction of the paper feed cassette, and a paper feed roller having an arm body that is rotatable up and down around a drive shaft is provided in the housing.

  Further, the paper feed tray is provided with a rear guide that abuts the trailing edge of the sheet (upstream edge in the transport direction) to maintain the accumulated state of the sheet. The leading edge (downstream edge in the conveyance direction) of the sheet thus formed is positioned close to the inclined separation plate.

The arm body includes a transmission mechanism that transmits power so as to rotate the paper feed roller forward and backward from the drive shaft. The sheet feeding roller is driven to rotate in a predetermined direction (the drive shaft rotates in the forward direction), so that the leading edge of the sheet abuts against the inclined separation wall formed at the downstream end of the sheet feeding tray in the conveyance direction. As a result, only the uppermost sheet is separated. The separated sheet is configured to convey the sheet to the image recording unit via a U-shaped conveyance path formed upward adjacent to the upper end of the inclined separation plate.
Japanese Patent Laying-Open No. 2006-062775 (see FIGS. 2, 6, and 11) Japanese Patent Laying-Open No. 2006-062776 (see FIGS. 2 and 6)

  As described above, when a paper feed roller is provided on a so-called pendulum type arm body, as the number of sheets fed and consumed increases, the amount of sheets deposited on the paper feed tray decreases. The height position of the paper feed roller contacting the uppermost sheet is also lowered.

  Here, from the leading edge of the sheet at a position close to the inclined separation plate, the detection by the sheet detection sensor located at the position of the registration roller pair in front of the image recording unit or upstream of the image recording unit through the conveyance path. The distance to the position (these are called predetermined positions) is defined as the tip conveyance path length. Then, in the case of the uppermost sheet when the paper tray is stacked in a full state and the case of the last sheet of the accumulated amount, at least along the surface of the inclined separation plate corresponding to the accumulated height. The length of the leading end conveyance path in the case of the last sheet is increased by the distance of the length. In other words, when the accumulated amount of sheets on the sheet feeding tray is large, the leading end transport path length is short, and the leading end transport path length becomes longer as the accumulated amount of sheets decreases.

  Therefore, assuming that the rotation speed of the paper feed roller or the drive shaft is constant, when the amount of sheets accumulated on the paper feed tray is large (the front end transport path length is short), the above-mentioned predetermined speed from the start of rotation of the paper feed roller. The rotational driving amount of the paper feed roller for conveying the sheet to the position is small. On the other hand, when the amount of accumulated sheets on the sheet feeding tray is small (the leading end conveyance path length is long), the rotation driving amount of the sheet feeding roller for conveying the sheet from the rotation start of the sheet feeding roller to the predetermined position. Will be more.

  For example, on the basis of a large amount of accumulated sheets on the sheet feeding tray, the rotation driving amount of the sheet feeding roller for conveying the sheet from the rotation start of the sheet feeding roller to the predetermined position (sheet sensor position) (or Time) is set. When the sheet feeding operation proceeds in this state, the amount of sheets deposited on the sheet feeding tray gradually decreases. Then, the rotational drive amount (or required time) required for the sheet feed roller for conveying the sheet from the start of rotation of the sheet feed roller to the predetermined position (sheet sensor position) gradually increases. As a result, the rotation driving amount (or required time) of the sheet feeding roller is set on the basis of the case where the amount of accumulated sheets is large, and when the set rotation driving amount (or setting required time) is reached, the rotation of the feeding roller is temporarily performed. If the control of stopping is executed, there is a possibility that a sheet conveyance unreasonable jam that the leading edge of the sheet does not reach the sheet sensor position may occur.

  On the other hand, when the rotation driving amount (or required time) of the sheet feeding roller is set on the basis of the case where the sheet accumulation amount in the sheet feeding tray is small, the sheet feeding roller in a state where the sheet accumulation amount in the sheet feeding tray is large. Is rotated for a set predetermined amount (or set required time), there is a possibility that paper jam such as bending of the sheet due to excessive feeding of the sheet may occur.

  In order to solve such an inconvenience, a sheet accumulation sensor or a detection sensor for detecting a rotation angle of the sheet feeding roller with respect to a reference angle and a sheet sensor are provided. Based on the detection value of the sensor, it is necessary to perform automatic control to execute a calculation for determining a necessary rotational driving amount of the paper feed roller. However, in such a configuration, there is a problem that the above-described sensor and calculation means (control means) that can continuously detect from full sheet loading to empty loading must be provided, which increases the size and cost of the apparatus. .

The present invention has been made to solve the above-described conventional problems, and the sheet conveyance path length (the trailing edge of the sheet abuts) regardless of the amount of sheets accumulated in the sheet feeding tray. The distance from the rear guide surface of the rear guide member to the predetermined position through the contact position of the sheet feeding roller and the conveying path (hereinafter the same) can be made substantially constant, and the sheet can be supplied stably. An object of the present invention is to provide an image recording apparatus provided with a mechanical mechanism.

  In order to achieve the above object, an invention according to claim 1 is a sheet feeding tray having a storage section capable of storing sheets in a stacked state, and for conveying the sheets one by one from the sheets stored in the sheet feeding tray. An image having a sheet feeding means, a conveying path for conveying the sheet from the sheet feeding tray, and an image recording unit capable of recording an image on the sheet conveyed from the sheet feeding tray via the conveying path. In the recording apparatus, the paper feeding unit is provided at an arm body rotatable about a drive shaft, and a distal end portion of the arm body, and the paper feed tray is driven by a driving force transmitted from the drive shaft. A sheet feeding roller that rotates while abutting against the uppermost sheet among the sheets stacked in the storage section, and the arm body is configured to perform the sheet feeding in accordance with forward rotation and reverse rotation of the drive shaft. Roller rotates forward and backward A rear guide member that regulates an upstream rear end edge of the sheet stored in the storage unit in the transport direction is disposed on the paper feed tray, and a rear guide surface of the rear guide member Is configured to be positioned upstream in the transport direction as the sheet stack height increases, and the transport path length from the rear guide surface to a predetermined position in the transport path is equal to the sheet stack height. Regardless of how it is configured to be substantially constant.

  According to a second aspect of the present invention, in the image recording apparatus according to the first aspect, the feeding roller is reversely rotated before the uppermost sheet is conveyed, so that the rear end side of the uppermost sheet is rotated. The edge is configured to once contact the rear guide surface.

  According to a third aspect of the present invention, in the image recording apparatus according to the first or second aspect, the positions at which the leading end portion and the trailing end portion of the conveyed sheet are detected by the sheet sensor provided in the conveying path are It is set at a predetermined position.

  According to a fourth aspect of the present invention, in the image recording apparatus according to any one of the first to third aspects, the rear guide member is movable along the conveying direction in accordance with the size of the sheet accumulated in the accommodating portion. It is composed of.

  According to a fifth aspect of the present invention, in the image recording apparatus according to any one of the first to fourth aspects, the rear guide member is configured such that its arrangement inclination angle can be changed and adjusted.

  According to a sixth aspect of the present invention, in the image recording apparatus according to any one of the first to fourth aspects, the arm body extends downstream in the insertion direction of the paper feed tray as it approaches the bottom surface of the paper feed tray. It is comprised as follows.

  As described above, according to the first aspect of the present invention, by devising the arrangement of the rear guide surface of the rear guide member provided in the paper feed tray, the transport path from the rear guide surface to a predetermined position in the transport path. The length is configured to be substantially constant regardless of the height of the stacked sheets. Therefore, even if the driving amount of the paper feed roller is substantially constant regardless of the sheet stacking height, there is no occurrence of paper jam due to insufficient feeding or excessive feeding of the sheet up to a predetermined position, and stable. There is an effect that the sheet feeding operation can be performed.

  According to the second aspect of the present invention, the sheet feeding roller is reversely rotated before the uppermost sheet is conveyed, so that the rear end side edge of the uppermost sheet once comes into contact with the rear guide surface. It is comprised as follows. Therefore, in addition to the effect of the invention of claim 1, the sensor capable of continuously detecting from full loading to empty loading of the arm body, such as the sensor for detecting the inclination angle of the arm body, the sheet sensor, and the computing means as in the prior art. There is no need to provide (control means), the structure is simplified, and there is an effect that an increase in size and cost of the apparatus can be avoided.

  According to the third aspect of the present invention, the position where the leading edge and the trailing edge of the conveyed sheet are detected by the sheet sensor provided in the conveying path is set to the predetermined position. Accordingly, the conveyance path length from the rear guide surface to a predetermined position in the conveyance path is substantially constant regardless of the amount of accumulated sheets (deposition height), and the sheet of the sheet feeding roller that is rotationally driven is fixed. A slip correction value when a slip is generated can be set easily and accurately, and a stable sheet feeding operation can be performed.

  According to the fourth aspect of the present invention, the rear guide member is configured to be movable along the conveyance direction in accordance with the size of the sheets accumulated in the accommodating portion. According to the first aspect of the present invention, it is possible to obtain the effect of the first aspect of the present invention by a simple operation of moving the rear guide member according to the size of the seat to be accommodated.

  According to the fifth aspect of the present invention, since the rear guide member is configured so that the arrangement inclination angle can be changed and adjusted, the slip ratio between the sheet feeding roller and the sheet changes. A stable sheet feeding operation can be performed according to the change of the sheet type.

  According to the sixth aspect of the invention, the arm body is configured to extend downstream in the insertion direction of the paper feed tray (downstream in the sheet conveyance direction) as it approaches the bottom surface of the paper feed tray. The slip ratio with respect to the sheet is greater when the sheet feeding roller is rotated in the reverse direction than when it is rotated in the forward direction, and the sheet protrudes from the rear guide member after the rear edge of the sheet abuts the rear guide surface of the rear guide member. Can also be eliminated.

  Next, embodiments of the present invention will be described in detail with reference to the drawings. 1 is an overall perspective view of a multifunctional image recording apparatus 1 according to an embodiment of the present invention, FIG. 2 is an image recording unit, FIG. 2 is a schematic plan view of the image recording unit, and FIG. 3 is an image recording unit and sheet fullness. 4 is a schematic side sectional view of the sheet feeding tray in a state, FIG. 4 is a schematic side sectional view of the sheet feeding tray in a state where the image recording unit and the sheet are few, and FIG. 5 is a perspective view of the sheet feeding tray in a state where the rear guide member is removed. FIG. 6A is a diagram illustrating the operation of the paper feed roller and the rear guide member when there is little slip, FIG. 6B is a diagram illustrating the operation of the paper feed roller and the rear guide member when there is a lot of slip, and FIG. FIG. 8A and FIG. 8B are cross-sectional views showing a third embodiment of the change in the rear guide member arrangement inclination, and FIG. 9 is the third embodiment. The top view of a form and FIG. 10 are the XX arrow line views of FIG.

[Basic structure of multi-function device 1]
As shown in FIG. 1, an opening 2a is opened on the front side (front side in FIG. 1) of a housing 2 (also referred to as an apparatus housing) in the multi-function device 1, and the opening 2a serves as a sheet. A paper feed tray 3 having an open top surface for storing paper (hereinafter referred to as paper) in a stacked state is mounted so as to be insertable / removable along the X-axis direction. A paper discharge tray 33 is mounted on the upper surface of the paper feed tray 3. Hereinafter, the side having the opening 2a of the housing 2 made of synthetic resin is referred to as the front (front), and is referred to as the rear (back, back), left and right of the apparatus based on this. As described above, the front-rear direction of the multi-function device 1 is the X-axis direction, and the left-right direction is the Y-axis direction. The term “insertion / removal” is not limited to the case where the paper feed tray 3 is detachable from the housing 2, and even when the paper feed tray 3 is pulled out of the housing 2, This is intended to include those in which the tray 3 cannot be removed (cannot be attached or detached).

  An image reading device 5 for reading a document in a copy function or a facsimile function is disposed on the upper part of the housing 2 made of synthetic resin. The image reading device 5 is configured to be vertically openable and closable with respect to one side end of the housing 2 via a pivot portion (not shown). Further, the upper surface of the image reading device 5 is constituted by a glass plate for placing a document, and this glass plate is a document cover body 6 that can be turned up and down around the pivot with respect to the rear end of the image reading device 5. Covered with. A document placed on the glass plate by opening and closing the document cover 6 is scanned by a document reading scanner (for example, CIS: Contact Image Sensor) that moves below the glass plate.

  On the upper surface of the housing 2 and in front of the document cover body 6, an operation panel unit 7 having various operation buttons and a liquid crystal display device 8 for displaying an operation procedure and a state of processing being executed are provided. ing. The various operation buttons include a start button, a stop button, and the like, and various operations are performed by pressing these operation buttons. In addition, the setting state of the multi-function device 1 and various operation messages are displayed as necessary.

  An external memory insertion portion 11 for inserting an external memory is provided on the front surface of the housing 2 and above the opening 2a. The external memory corresponds to, for example, CompactFlash (registered trademark), SmartMedia (registered trademark), Memory Stick (registered trademark), SD card (registered trademark), xD (registered trademark), and the like. The data stored in the external memory inserted into the external memory insertion unit 11 is read into the internal memory of the multi-function device 1 and recorded on the paper by the recording device.

  Next, the image recording unit 10 and the paper feeding unit 30 will be described with reference to FIGS. 3 and 4 are side sectional views of the image recording unit 10 and the paper feed tray.

[Image recording section]
The image recording unit 10 is supported by a box-shaped main frame 21 (see FIG. 2) having an open upper surface and a pair of left and right side plates, and extends in the Y-axis direction (main scanning direction) as shown in FIG. It is formed between the horizontally long plate-like first and second guide members 22 and 23. The carriage 13 in which the recording head 14 in the image recording unit 10 is mounted on the lower surface side is slidably supported across the first guide member 22 on the upstream side and the second guide member 23 on the downstream side in the paper transport direction. (Mounted) and can be reciprocated.

  In order to reciprocate the carriage 13, a timing belt 24 arranged to extend in the main scanning direction is provided on the pulley on the upper surface of the second guide member 23 arranged on the downstream side in the paper transport direction (arrow A direction). A CR (carriage) motor 25 that is wound and drives the timing belt 24 is fixed to the lower surface of the second guide member 23.

  A flat platen 26 extending in the Y-axis direction so as to face the lower surface of the recording head 14 in the carriage 13 is fixed between the guide members 22 and 23 and above the bottom plate of the main frame 21. . A space between the platen 26 and the bottom plate (not shown) of the housing 2 is a tray storage portion that stores a paper feed tray 3 described later and that can be inserted and removed. At least a part of the bottom plate 3 a of the paper feed tray 3 is supported on the bottom plate of the housing 2. Then, ink is supplied from the ink tank 15 accommodated in the housing 2 to the recording head 14 via the flexible ink tube 20 (see FIG. 2). The ink tank 15 can be replaced for each of the four colors of black, cyan, magenta, and yellow.

  In addition, a registration roller (conveyance roller) pair 27 for sending the sheet to the lower surface of the recording head 14 is disposed on the upstream side of the conveyance with the platen 26 interposed therebetween. When passing over the platen 26, an image is recorded on the paper P. Disposed on the downstream side of the platen 26 is a pair of paper discharge rollers 28 for transporting the recorded paper P onto a paper discharge tray section 33 provided on the upper surface of the paper feed tray 3.

[Paper Tray]
The sheet accommodated in the sheet feeding tray 3 is hereinafter referred to as a sheet for convenience. The sheet includes not only plain paper but also special paper such as postcards and envelopes, special paper such as glossy paper, and resin films. It is a concept.

  Next, the configuration of the paper feed tray 3 will be described in detail. The container 3b of the paper feed tray 3, which is an injection molded product of synthetic resin material, has an open top surface. For example, the A4 size paper P has a long side along the X-axis direction and a short side along the Y-axis direction. It is accommodated so as to be along. The accommodating portion 3b includes a bottom plate 3a, left and right side plates 3c, and an inclined separation plate 18 connected to the downstream end in the transport direction. A handle 3f is provided at the rear end of the housing 3b. An elastic separation piece 18a (see FIGS. 3, 4, and 5; in the embodiment, made of a leaf spring) is provided at the center of the inclined separation plate 18 in the Y-axis direction.

  In the embodiment, the maximum accumulation amount of the paper P on the paper feed tray 3 is about 150 sheets of plain paper, and the accumulation height is about 15 mm. The sheets P in the sheet feed tray 3 are separated one by one by the cooperative action of a pendulum-type sheet feeding means 30 (to be described later) and an elastic separation piece 18a in the inclined separation plate 18, and then conveyed in a U-turn shape. The paper is conveyed to the image recording unit 10 one by one through the road bodies 32a and 32b.

  A paper sensor 31 that detects the leading edge and the trailing edge of the paper P to be transported is provided on the transport path formed by the transport path bodies 32a and 32b. In the embodiment, the sheet sensor 31 is an optical sensor that is provided upstream of the registration roller pair 27 in the conveyance direction, and the light emitting unit and the light receiving unit are arranged with the conveyance path interposed therebetween.

[Paper Feed]
Next, the structure of the sheet feeding means (also referred to as a sheet feeding roller unit) 30 will be described in detail with reference to FIGS. 3, 4, 6 (A) and 6 (B). In the embodiment, the arm 30c made of synthetic resin in the paper feeding means 30 can be turned up and down around the drive shaft 39, and the arm 30c approaches the bottom plate (bottom surface) 3a of the paper feed tray 3. The arm body 30c extends so as to approach the inclined separation plate 18, and a paper feed roller 30a is disposed at the tip of the arm body 30c. The pair of paper feed rollers 30a in the embodiment are provided at symmetrical positions with respect to the center line in the Y-axis direction. The LF motor 52 (see FIG. 11) can rotate forward and backward, and the drive shaft 39 is rotationally driven by the LF motor 52.

  The arm body 30c is provided with a gear transmission mechanism (transmission mechanism) 35 including a plurality of gears, and transmits the rotational force from the drive shaft 39 to the paper feed roller 30a. In FIG. 6 (A) and FIG. 6 (B), the gear transmission mechanism 35 is not shown. A rotary encoder 53 (see FIG. 11) for detecting the direction and amount of rotation is provided in the gear transmission to the LF motor 52 or the drive shaft 39. In the present embodiment, the rotational force of the LF motor 52 is configured to be selectively transmitted to the drive shaft 39 and the registration roller pair 27 via a power transmission switching mechanism (not shown). The registration roller pair 27 (including the paper discharge roller pair 28) may be driven by separate motors.

[Rear guide member]
Next, the rear guide member 40 provided in the paper feed tray 3 will be described. The rear guide member 40 is provided on the downstream side of the sheet feeding tray 3 in the sheet conveying direction (a position away from the inclined separation plate 18), and upstream in the conveying direction of the paper P accumulated in the storage portion 3b of the sheet feeding tray 3. The rear end side edge of the side is regulated. In the present invention, the conveyance path length from the rear guide surface 41 to a predetermined position in the conveyance path of the rear guide member 40 is configured to be substantially constant regardless of the height of the sheet P accumulated. . Here, the predetermined position refers to a position of the registration roller pair 27 in front of the image recording unit 10 or a detection position by the paper detection sensor 31 positioned on the upstream side of the transfer. Further, the conveyance path length refers to the contact position of the paper P by the paper feed roller 30a and the conveyance path between the conveyance path bodies 32a and 32b from the rear guide surface 41 of the rear guide member 40 with which the rear edge of the paper P abuts. The distance to the predetermined position. In this embodiment, the distance to the detection position by the paper detection sensor 31. The rear guide member 40 is configured to be movable along a positioning engagement claw row 42 formed on the bottom plate 3a of the paper feed tray 3 so as to extend along the X-axis direction. Further, the rear guide member 40 is disposed so that the rear edge of the paper P abuts at a position near the center in the width direction of the paper P.

  In the present invention, the rear guide surface 41 of the rear guide member 40 is configured to be positioned on the upstream side in the transport direction as the accumulation height of the paper P increases. For example, in FIG. 3 and FIG. 4, the rear guide surface 41 increases in the conveyance direction upstream side (inclined separation plate) as the height from the bottom plate 3 a of the paper feed tray 3 becomes higher in the side sectional view of the paper feed tray 3. It is inclined so as to be biased toward the side (away from 18) and is formed in a sawtooth shape. In the embodiment shown in FIGS. 6A and 6B, the rear guide surface 41 is an inclined plane.

  Further, in the present invention, the feeding roller 30a is reversely rotated before the uppermost sheet P stacked and accommodated in the sheet feeding tray 3 so that the rear end side edge of the uppermost sheet P is once at the rear guide surface. Then, after the sheet 41 is brought into contact with the sheet 41, the sheet feeding roller 30a is rotated forward to carry the sheet P.

  In the above configuration, when separating and transporting the sheets P from the sheet feed tray 3 one by one, the LF motor 52 (see FIG. 11) rotates forward and the drive shaft 39 rotates forward. Then, the arm body 30 c is urged downward through the transmission gear group 35, and the paper feed roller 30 a at the tip of the arm body 30 c is pressed against the uppermost surface of the paper P deposited on the paper feed tray 3. On the other hand, the paper feed roller 30a is rotated in the conveying direction (clockwise direction in FIGS. 3 and 4) via the gear transmission mechanism 35.

  Accordingly, the uppermost sheet and the leading ends of the plurality of sheets P below it are moved in the direction approaching the inclined separation plate 18 by the rotationally driven paper feed roller 30a, but the cooperative action of the inclined separation plate 18 with the separating means 18a. Thus, only the uppermost sheet P in the storage section 3b is separated and conveyed (paper fed) to the conveyance path between the conveyance path bodies 32a and 32b.

  When the leading edge of the conveyed paper P crosses the location of the paper sensor 31, a predetermined signal (pre-registration signal) is output to the control device 50 (see FIG. 11). The controller 50 calculates the registration feed rotation amount of the LF motor 52 corresponding to the distance of the sheet conveyance path from the position of the sheet sensor 31 to the registration roller pair 27 using the pre-registration signal as a trigger, and if the registration rotation amount is reached. Then, the LF motor 52 is temporarily stopped and the sheet P is subjected to a resist action. Since the resist action for preventing the skew of the paper P and for cuing it is a well-known technique, its description is omitted here. Thereafter, when an image print command is output, the control device 50 performs a normal rotation of the registration roller pair 27 that transports the paper P in the direction of the carriage 13 and a rotational drive of the paper feed roller 30a in the transport direction according to the command To do.

  When the leading end portion of the paper P is nipped by the registration roller pair 27, it is left to the conveyance of the paper P by the registration roller pair 27.

  When the image recording on the preceding one sheet P is completed and the sheet sensor 31 detects the trailing edge of the sheet P, a command to convey the subsequent sheet P from the sheet feed tray 3 is output. In that case, after the drive shaft 39 is rotated in the reverse direction, the paper feed roller 30a is rotated in the reverse direction, and the rear edge of the uppermost sheet P is brought into contact with the rear guide surface 41 of the rear guide member 40. Then, the drive shaft 39 is rotated in the forward direction, and the conveyance of the paper P is started by the forward rotation of the paper feed roller 30a (hereinafter referred to as paper feed start). In this case, the arm body 30c is configured to extend to the downstream side in the insertion direction of the paper feed tray 3 (downstream side in the sheet conveyance direction) as it approaches the bottom surface of the paper feed tray 3, so the paper feed roller 30a The slip rate with respect to the sheet P becomes larger during the reverse rotation than during the forward rotation of the sheet P, and the sheet P protrudes from the rear guide member 40 after the rear edge of the sheet P contacts the rear guide surface 41 of the rear guide member 40. This problem can be solved.

  By configuring as described above, even when the leading edge of the paper P accumulated in the storage portion 3b of the paper feed tray 3 is in contact with the inclined separation plate 18, the paper P is transported before the conveyance. By rotating the paper feed roller 30 a in the reverse direction, the trailing edge of the paper P can be retracted so as to contact the rear guide surface 41. As described above, the uppermost paper P when the paper is stacked on the paper feed tray 3 and the case where the amount of the accumulated paper is the last paper P correspond to at least the height of the accumulated paper. The length of the leading end conveyance path in the case of the last sheet of paper P is increased by the distance of the length along the surface of the inclined separation plate 18. In other words, when the accumulation amount of the paper P on the paper feed tray is large, the front end conveyance path length is short, and the front end conveyance path length gradually increases as the accumulation amount of the paper P decreases. However, as described above, if the rear guide surface 41 is configured to be positioned on the upstream side in the transport direction as the accumulation height of the paper P increases, the rear edge of the paper P when the paper P is full is in contact with the rear guide surface 41. The rear end retractable distance Lk1 can be larger than the rear end retractable distance Lk0 until the rear end edge of the last sheet P contacts the rear guide surface 41 (see FIG. 6A).

  Accordingly, by appropriately setting the inclination angle β of the rear guide surface 41 (that is, the rearward inclination angle with respect to the bottom plate 3a), for example, in FIG. 6A, the conveyance path length Lu (= c0 point when full) (sheet sensor 31). The distance between the detection position of the sheet P and the position of the rear end of the sheet P with respect to the rear guide surface 41) and the transport path length Ld for the last sheet P of paper. (= C0 point → c1 point → c5 point → c6 point → c7 (distance between the abutment position of the rear end of the paper P with respect to the rear guide surface 41)) can be set to be substantially equal. Here, the length from the point c2 to the point c3 and the length from the point c5 to the point c6 correspond to the length of the paper P along the x-axis direction, and the length from the point c1 to the point c2 is the above-mentioned rear end. This corresponds to the retractable distance Lk1 (the length from the c3 point to the c4 point), and the length from the c6 point to the c7 point corresponds to the rear end retractable distance Lk0.

  If configured as described above, assuming that the rotation amount (rotation speed or unit drive amount) per unit time of the drive shaft 39 and thus the paper feed roller 30a is constant, the transport path length Lu at the time of full and the last As a result of the conveyance path length Ld for a single sheet P being substantially equal, the drive shaft 39 is driven to rotate in the positive direction required to convey the sheet to the recording unit 10 regardless of the amount of accumulation of the sheet P. The amount can be constant. As a result, the transport time Th (measured by the timer 54) of the paper P from the start of paper feeding to the paper sensor 31 can be made substantially (almost) constant regardless of the amount of the paper P accumulated. The drive amount of the drive shaft 39 can be calculated by the rotary encoder 53.

  When the slip rate of the paper feed roller 30a with respect to the paper P is small, as shown in FIG. 6A, the inclination angle β1 of the rear guide surface 41 is set large, and the slip rate of the paper feed roller 30a with respect to the paper P is large. For this, as shown in FIG. 6B, the inclination angle β2 of the rear guide surface 41 may be set small. In that case, a plurality of types of rear guide members 40 with different inclination angles of the rear guide surface 41 are prepared, and the mounting is exchanged.

  FIG. 7 shows a second embodiment in which the inclination angle of the rear guide surface 41 can be adjusted to be larger or smaller, and the first rear guide member on the lower surface side of the triangular block-shaped first rear guide member 43 in a side view. The second rear guide member 44 having a recess corresponding to the shape of 43 is configured to be detachable from the side or from above. The inclination angle β2 of the rear guide surface 41 of the second rear guide member 44 is set to be smaller than the inclination angle β1 of the rear guide surface 41 of the first rear guide member 43. According to this configuration, the replacement work of the rear guide member can be performed with one touch.

  FIGS. 8A and 8B and FIGS. 9 and 10 show a third embodiment. By changing and adjusting the arrangement inclination angle of the rear guide member 55 to be larger or smaller, the inclination angle of the rear guide surface 58a can also be changed. The rear guide member 55 includes a base body 56, a contact member 58 having a pair of serrated rear guide surfaces 58 a, and a link body 57 that is supported on the back side of the contact member 58. A base end pin 58 b of the contact member 58 is rotatably supported by a bearing portion 59 formed on the upper surface of the base body 56. A round shaft 57a at the base end (lower end) of the link body 57 rotatably connected to a pair of side surfaces of the contact member 58 is detachable from an engaging portion 60 that is formed on the upper surface of the base body 56 and can be adjusted in position. Is engaged. The engagement portion 60 is provided at a plurality of locations (two locations in the embodiment) along the perspective direction with respect to the proximal end pin 58b of the contact member 58. Therefore, when the round shaft 57a is engaged with the engaging portion 60 on the side close to the proximal pin 58b, the inclination angle of the contact member 58 is held large (closer to 90 degrees) (FIG. 8A). reference). Conversely, when the round shaft 57a is engaged with the engaging portion 60 on the side far from the proximal pin 58b, the inclination angle of the contact member 58 becomes small (see FIG. 8B).

  On the lower surface side of the base body 56, a linear guide protrusion 61 and a retaining piece 62 connected to the lower surface thereof are integrally formed. On the other hand, a linear guide groove hole 63 is formed through the bottom plate 3 a of the paper feed tray 3 between the pair of engaging claw rows 42. Accordingly, when the guide protrusion 61 is fitted into the guide groove hole 63 and is inserted from a mounting portion (not shown) so that the retaining piece 62 is positioned on the lower surface side of the bottom plate 3 a, the base plate 56 and the retaining piece 62 form the bottom plate. It can move along the X-axis direction with 3a sandwiched between the top and bottom. The pair of locking claws 65 formed on the lower surface of the elastic piece 64 provided on the rear side (upstream side in the transport direction) of the base body 56 engages with an arbitrary position of the pair of engagement claw rows 42. Thus, the position of the rear guide member 55 is maintained. The latching claw portion 65 is separated from the engagement claw row 42 by pushing the knob 64a projecting upward on the elastic piece 64 upward, and the position of the rear guide member 55 in the X-axis direction can be changed in this state. it can.

  As described above, even if the inclination angle of the contact member 58 is changed in size, the sawtooth rear guide surface 58a formed on the surface of the contact member 58 stands up to a state close to 90 degrees with respect to the surface of the bottom plate 3a. Therefore, when the rear end edge of the paper P that has been retracted by the paper supply roller 30a is brought into contact with the rear guide surface 58a, the frictional resistance of the rear guide surface 58a can be increased. It is possible to reliably prevent the member 55 from getting over the upper end of the member 55 and protruding to the upstream side of the conveyance.

  By configuring as described above, it is necessary to include a detection sensor capable of continuously detecting from full loading to empty loading of the paper, such as a sensor for detecting the inclination angle of the arm body 30c, the paper sensor 31, and a calculation means (control means). Therefore, the configuration is simplified, and the increase in size and cost of the apparatus can be avoided.

  When the drive amount or the required time of the drive shaft 39 or the paper feed roller 30a is a theoretical value when no slip occurs between the rotating paper feed roller 30a and the paper P, In the state where slip is occurring, the slip amount is the difference between the actually calculated or measured drive amount or the required time and the theoretical value. In the present invention, by determining the slip correction value based on this slip amount, it is possible to set an optimum slip correction value regardless of the amount of accumulation of the paper P. Problems related to the performance of the image recording apparatus, such as failure of the sheet P to reach the sensor, can be easily solved. Note that the slip amount (slip rate) varies depending on the type of the paper P, assuming that the friction coefficient of the outer peripheral surface of the paper feed roller 30a is constant.

  The present invention is not limited to the embodiments described with reference to the above description and drawings, and various modifications can be made without departing from the scope of the invention. For example, a pair of left and right paper feed rollers 30a as the paper feed rollers or only one of the paper feed rollers 30a may be used. Further, the outer peripheral surface of the paper feed roller 30a may be configured by a member having a large friction coefficient such as rubber. Furthermore, a surface layer (material) having a high coefficient of friction may be applied or adhered to the surface of the flat rear guide surface 41.

1 is an overall perspective view of an image recording apparatus. It is a schematic plan view of an image recording part. FIG. 3 is a side sectional view of an image recording unit and a paper feed tray when a paper P is full. 4 is a side sectional view of an image recording unit and a paper feed tray when there is only one sheet of paper P. FIG. FIG. 6 is a perspective view of a paper feed tray with a rear guide member omitted. (A) is an operation explanatory diagram in a state where the slip rate is low, and (B) is an operation explanatory diagram in a state where the slip rate is high. It is a schematic sectional side view which shows 2nd Embodiment of the replaceable rear guide member. (A) is a side view of the rear guide member according to the third embodiment in a state where the arrangement inclination angle is large, and (B) is a side view of a state where the arrangement inclination angle is small. It is a top view of 3rd Embodiment of a rear guide member. It is the XX arrow directional view of FIG. It is a functional block diagram of a control device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Paper feed tray 3a Bottom plate 30 Paper feed means 30a Paper feed roller 30c Arm body 31 Paper sensor 35 Transmission gear group 35 Transmission gear mechanism 39 Drive shaft 40, 43, 44, 55 Rear guide member 41, 58a Rear guide surface

Claims (6)

A sheet feeding tray having a storage section capable of storing sheets in a stacked state; a sheet feeding means for conveying sheets one by one from the sheets stored in the sheet feeding tray; and conveyance for conveying the sheets from the sheet feeding tray An image recording apparatus having a path and an image recording unit capable of recording an image on a sheet conveyed from the sheet feeding tray via the conveyance path,
The sheet feeding means is provided at an arm body rotatable around a drive shaft and a tip portion of the arm body, and is deposited in the accommodating portion of the sheet feed tray by a driving force transmitted from the drive shaft. A sheet feeding roller that rotates while contacting the uppermost sheet, and the arm body is configured so that the sheet feeding roller rotates forward and backward in accordance with forward and reverse rotations of the drive shaft. It has a transmission mechanism that rotates,
A rear guide member that regulates an upstream rear end side edge in the transport direction of the sheet stored in the storage unit is disposed in the paper feed tray.
The rear guide surface of the rear guide member is configured to be positioned on the upstream side in the transport direction as the accumulated height of the sheet increases.
An image recording apparatus, wherein a length of a conveyance path from the rear guide surface to a predetermined position in the conveyance path is substantially constant regardless of a stack height of the sheet.   The sheet feeding roller is reversely rotated before the uppermost sheet is conveyed, and the rear end side edge of the uppermost sheet is configured to temporarily contact the rear guide surface. The image recording apparatus according to claim 1.   3. The image recording according to claim 1, wherein a position at which a front end portion and a rear end portion of the conveyed sheet are detected by a sheet sensor provided in the conveyance path is set to the predetermined position. apparatus.   4. The image recording apparatus according to claim 1, wherein the rear guide member is configured to be movable along a conveyance direction in accordance with a size of a sheet accumulated in the storage portion. 5.   The image recording apparatus according to claim 1, wherein the rear guide member is configured so that an arrangement inclination angle thereof can be changed and adjusted.   5. The image recording apparatus according to claim 1, wherein the arm body is configured to extend downstream in the insertion direction of the paper feed tray as it approaches the bottom surface of the paper feed tray. .

Images