JP2005060028A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of placing a recording medium on a placing surface without generating cylindrical curl. <P>SOLUTION: In a replaceable adapter 16 installed on a bottom surface 13 of a paper discharging tray 11, one end side surface from a top portion 16c of a projecting portion 16b is formed to tilt upward at 30° from one end side relative to a horizontal direction, and the other end side surface from the top portion 16c of the projecting portion 16b is formed to make an angle with a horizontal surface in a range wherein a paper sheet α does not move in a paper discharging direction by the weight of the paper sheet α itself, when the paper sheet α is placed. When the paper α is placed on the placing surface 17 of a laser printer 1, the paper sheet α is placed so as to make a middle part of the paper sheet α bulge upward in a cross section view along the paper discharging direction. The paper sheet α is regulated to displace in a right-and-left direction which is vertical to the paper discharging direction, thereby preventing the generation of the cylindrical curl. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus.

Conventionally, in the laser printer 100, as shown in FIG. 7, an image developed with toner is formed on a photosensitive drum 62, and the image is transferred to a paper α and pressed with a heating roller 81 heated to about 200 ° C. The image is fixed on the paper α by melting the toner with heat generated from the heating roller 81 with the paper α sandwiched between the rollers 82. Then, the paper α on which the image is fixed is discharged onto a paper discharge tray 11 formed on the upper surface of the main body casing 10 via a paper discharge roller 92. As this type of laser printer, for example, those disclosed in the following publications are known.
JP 2001-146355 A

  Incidentally, the paper α generally contains several percent of water with respect to its weight. The moisture evaporates when the paper α passes through the heating roller 81 and the like, and the amount of moisture evaporated is larger on the front side (the side on which the image is transferred) of the paper α on which the heating roller 81 hits. Since the amount is larger than that on the back side, the moisture content of the paper α is biased.

  Also, the sheet α is bent in a complicated manner when it is conveyed from the tray 30 via the heating roller 81 and the like to the sheet discharge roller 92. When being conveyed between the two, it is conveyed in a state of being curled in the conveying direction.

  Therefore, after the paper α is discharged onto the paper discharge tray 11, a so-called cylindrical curl is generated in which the end in the width direction of the paper (left and right direction perpendicular to the paper transport direction) is rounded inward. was there.

  When this cylinder curl occurs, the paper α previously discharged to the paper discharge tray 11 becomes higher in the thickness direction of the paper α, so that it is pushed by the paper α discharged after the paper discharge roller 92. There is a problem in that the paper α cannot be stacked on the paper discharge tray 11 by a height that causes the paper to jump out of the paper discharge tray 11 or curl.

  Therefore, an object of the present invention is to provide an image forming apparatus capable of placing a recording medium on a placement surface without causing a cylinder curl.

  In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that a mounting surface on which a sheet-like recording medium can be placed is formed on the upper surface of the casing of the apparatus main body, and image formation in the casing is performed. An image forming apparatus configured to dispose one end of the mounting surface below a discharge roller that discharges the recording medium on which the image is formed on the stacking surface onto the stacking surface. The placement surface has a convex portion that is raised upward between the one end and the other end, which are upstream in the paper discharge direction of the paper discharge roller, and the surface on the one end side from the top of the convex portion. Is inclined at an angle in the range of 25 ° to 55 ° above the one end side with respect to the horizontal direction.

  When the paper is placed on the placement surface of the image forming apparatus, the paper is placed so that it is slightly bent with the middle of the paper raised upward when viewed in a section along the paper discharge direction. Therefore, the sheet is restricted from being displaced inward in the left and right ends perpendicular to the sheet discharge direction, and the above-described cylinder curl is prevented from occurring.

Therefore, the image forming apparatus of the present invention can place the recording medium on the placement surface without causing cylinder curl.
In addition, since the image forming apparatus of the present invention does not generate a cylindrical curl, more recording media can be placed on the paper discharge tray than a conventional image forming apparatus having a paper discharge tray of the same depth. . For this reason, when manufacturing an image forming apparatus capable of mounting the same number of recording media on a paper discharge tray, the image forming apparatus of the present invention has a shallower discharge than a conventional image forming apparatus in which cylindrical curling occurs. Since it is sufficient to form a paper tray, the entire apparatus can be reduced in size.

In addition, it is more preferable that the surface on the one end side from the top of the convex portion is inclined at an angle in the range of 27 ° or more and 50 ° or less above the one end side with respect to the horizontal direction.
In the image forming apparatus of the present invention, one end side of the paper placed on the placement surface is placed above the horizontal at the angle as described above, and the paper is placed on the other end side from the convex portion. It is preferable to form in a shape that can be placed horizontally or slightly below horizontal. With this configuration, the paper on one end side does not jump up, so that it is possible to prevent the paper discharge roller from blocking the paper discharge port that discharges the paper.

  Next, as in the image forming apparatus according to the second aspect, the length from one end on the discharge roller side to the top of the convex portion is about half the length of the recording medium in the sheet discharge direction. Preferably it is formed. If comprised in this way, generation | occurrence | production of a cylinder curl can be suppressed effectively. The length from one end on the paper discharge roller side to the top of the convex portion is preferably 40-60% of the length of the recording medium in the paper discharge direction, and is 45% -55% long. More preferably.

  Next, as in the image forming apparatus according to the third aspect, it is preferable that the mounting surface is formed to have a size capable of mounting an A4 size recording medium. This is because A4 size recording media are most in demand.

  Next, as in the image forming apparatus according to the fourth aspect, the surface on the other end side from the top of the convex portion and the upper surface of the housing of the apparatus main body connected to the surface are placed when the recording medium is placed. The recording medium is preferably formed so as to form an angle with the horizontal plane as long as the recording medium moves in the paper discharge direction due to the weight of the recording medium and does not fall from the mounting surface. In this way, the recording medium can be placed on the placement surface without dropping from the other end side of the placement surface.

  Next, as in the image forming apparatus according to claim 5, the convex portion has an angle formed between a surface on one end side from the top of the convex portion and a surface on the end side from the top portion of 120 ° or more and 165. It is preferable to configure so as to be within a range of less than or equal to °. When configured within an angle within this range, tube curling is particularly difficult to occur. In addition, it is more preferable that the angle described above is 130 ° to 150 °.

  Next, as in the image forming apparatus according to the sixth aspect, the mounting surface is formed in a shape in which the recording medium bends in accordance with the shape of the convex portion until at least 100 recording media are stacked. It is preferable that In this image forming apparatus, the recording medium bends at least 100 sheets following the shape of the convex portion, so that the recording medium can be placed on the placement surface without being shifted in the paper discharge direction.

  Next, as in the image forming apparatus according to the seventh aspect, it is preferable that one end of the placement surface has a sheet rear end contact surface orthogonal to the horizontal plane. In this way, the recording medium can be placed on the placement surface along the sheet rear end contact surface.

  Next, as in the image forming apparatus according to the eighth aspect, it is preferable to include a sheet pressing member that comes into contact with the recording medium on the downstream side of the sheet discharge roller in the sheet discharge direction from above. When the paper pressing member is provided, the recording medium is pressed from above, so that it is possible to more effectively prevent the recording medium placed on the placement surface from being displaced in the paper transport direction or the left-right direction. .

  Next, as in the image forming apparatus according to the ninth aspect, the convex portion is provided with a width wider than the paper length in the same direction as the left-right direction with respect to the left-right direction perpendicular to the paper discharge direction. preferable. If the convex portion is configured in this way, the recording medium can be mounted on the mounting surface in a state where cylinder curling can be effectively prevented even when the recording medium is displaced in the left-right direction.

  Next, as in the image forming apparatus according to the tenth aspect, the housing includes a main body case that forms a main body portion of the housing, and a convex portion that is formed of a separate member from the main body case. The convex portion may be placed on the upper surface of the main body case. And when formed in this way, as described in Claim 11, you may comprise a convex-shaped part so that attachment or detachment is possible on a main body case upper surface.

Preferred embodiments of the present invention will be described below with reference to the drawings. The same devices as those shown in the background art column are denoted by the same reference numerals and will be described below.
FIG. 1 is a side sectional view showing an embodiment of a laser printer as an image forming apparatus of the present invention, and FIG. 2 is a schematic diagram of the laser printer 1. As shown in FIG. 1, the laser printer 1 according to this embodiment includes a feeder unit 3 for feeding a sheet α as a recording medium and a sheet fed into a main body casing 10 as a casing of the apparatus main body. An image forming unit 5 for forming a predetermined image on the paper α, a paper discharge unit 9 for discharging the paper α on which the image is formed by the image forming unit 5, and the like are provided.

  The feeder unit 3 includes a paper feed tray 30 that is detachably attached to the bottom of the main body casing 10, a paper pressing plate 31 provided in the paper feed tray 30, and one end side end of the paper feed tray 30. A pair of paper feed rollers 32 (32 a, 32 b) and a paper feed pad 33 provided above, registration rollers 34 and 35 provided on the downstream side of the paper feed roller 32 in the conveyance direction of the paper α, and registration rollers 35 On the other hand, a paper dust removing roller 36 provided on the downstream side in the conveyance direction of the paper α and a registration roller 37 provided on the downstream side of the paper dust removing roller 36 are provided.

  The paper pressing plate 31 can stack the paper α in a laminated form, and is supported so as to be swingable at the end far from the paper feed roller 32, so that the near end moves up and down. It is made possible, and is biased upward by a spring (not shown) from the back side. Further, when the paper pressing plate 31 is urged upward, the paper α placed on the plate surface at the near end is disposed at a position where the paper α comes into contact with one paper feed roller 32a. For this reason, the thickness of the paper α sandwiched between the paper feed roller 32a and the plate surface of the paper pressing plate 31 increases as the amount of stacked paper α increases. It moves downward against the energizing force of panes, with the end of the fulcrum as a fulcrum.

  Of the pair of paper feed rollers 32, the paper feed roller 32 b and the paper feed pad 33 on the downstream side are arranged to face each other, and the paper feed pad 33 is moved by a spring 38 arranged on the back side of the paper feed pad 33. It is pressed toward the paper feed roller 32b. The uppermost sheet α on the sheet pressing plate 31 is conveyed to the downstream side by the rotation of the sheet feeding roller 32a, and is fed one by one after being sandwiched between the sheet feeding roller 32b and the sheet feeding pad 33 on the downstream side. Paper. The fed paper α is sent further downstream by registration rollers 34, 35, paper dust is removed by a paper dust removing roller 36, and then sent to a registration roller 37. The registration roller 37 is composed of a pair of rollers, and sends the paper α to the image forming unit 5 after a predetermined registration.

  The feeder unit 3 further includes a multi-purpose tray 40, a multi-purpose side feed roller 41 and a multi-bar pass side feed pad 42 for feeding sheets α stacked on the multi-purpose tray 40. The multi-purpose-side paper feed roller 41 and the multi-purpose-side paper feed pad 42 are arranged so as to face each other, and the multi-purpose-side paper feed pad 42 is arranged on the back side of the multi-purpose-side paper feed pad 42 by a spring (not shown). The side paper feed pad 42 is pressed toward the multi-purpose side paper feed roller 41. The sheets α stacked on the multi-purpose tray 40 are fed one by one after being sandwiched between the multi-purpose side feed roller 41 and the multi-purpose side feed pad 42 by the rotation of the multi-purpose side feed roller 41. Is done. The fed paper α is sent further downstream by the registration roller 35, and after the paper dust is removed by the paper dust removing roller 36, it is sent to the registration roller 37. The registration roller 37 is composed of a pair of rollers, and sends the paper α to the image forming unit 5 after a predetermined registration.

The image forming unit 5 includes a scanner unit 50, a process unit 60, a fixing unit 80, and the like.
The scanner unit 50 is provided in the upper part of the main body casing 10, and includes a laser diode (not shown), a polygon mirror 51 that is driven to rotate, lenses 52 and 53, reflecting mirrors 54, 55, and 56, and the like, and emits light from the laser diode. The laser beam based on the predetermined image data is passed through the polygon mirror 51, the fθ lens 52, the reflecting mirrors 54 and 55, the cylinder lens 53, and the reflecting mirror 56 in this order, as indicated by the hollow line with the symbol β. The light is reflected and irradiated at high speed onto the surface of a photosensitive drum 62 of the process unit 60 described later.

  The process unit 60 is disposed below the scanner unit 50, and in a drum cartridge 61 that is detachably attached to the main body casing 10, a photosensitive drum 62, a developing cartridge 63, a scorotron charger 64, and a transfer roller 65. And a conductive brush 66 and the like.

  The developing cartridge 63 is detachably attached to the drum cartridge 61, and includes a developing roller 67, a layer thickness regulating blade 68, a supply roller 69, a toner box 70, and the like.

  The toner box 70 is filled with a positively charged non-magnetic one-component toner as a developer. Examples of the toner include polymerizable monomers such as styrene monomers such as styrene, and acrylic monomers such as acrylic acid, alkyl (C1 to C4) acrylate, and alkyl (C1 to C4) methacrylate. Polymerized toners obtained by copolymerization by a known polymerization method such as suspension polymerization are used. Such a polymerized toner is spherical and has very good fluidity. Such a toner is blended with a colorant such as carbon black, wax, and the like, and an additive such as silica is added to improve fluidity. The particle diameter is about 6 to 10 μm.

  Then, the toner in the toner box 70 is agitated by an agitator 72 supported by a rotating shaft 71 provided at the center of the toner box 70, and then from the toner supply port opened on the side of the toner box 70 to the supply roller 69 side. Released.

  A supply roller 69 is rotatably disposed at a side position of the toner supply port 73, and a developing roller 67 is rotatably disposed opposite to the supply roller 69. The supply roller 69 and the developing roller 67 are in contact with each other in a state where they are compressed to some extent.

  The supply roller 69 has a metal roller shaft covered with a roller made of a conductive foam material. In the developing roller 67, a metal roller shaft is covered with a roller made of a conductive rubber material. More specifically, the roller portion of the developing roller 67 is made of a urethane rubber or silicone rubber coating layer containing fluorine on the surface of a roller body made of an electrified urethane rubber or silicone rubber containing carbon fine particles. Has been revealed. A predetermined developing bias is applied to the developing roller 67 with respect to the photosensitive drum 62.

  A layer thickness regulating blade 68 is disposed in the vicinity of the developing roller 67. The layer thickness regulating blade 68 includes a pressing portion 68a having a semicircular cross section made of insulating silicone rubber at the tip of a blade body made of a metal leaf spring material. 73, the pressing portion 68a is configured to be pressed against the developing roller 67 by the elastic force of the blade body.

  The toner discharged from the toner supply port 73 is supplied to the developing roller 67 by the rotation of the supplying roller 69. At this time, the toner is positively frictionally charged between the supplying roller 69 and the developing roller 67, and further developed. As the developing roller 67 rotates, the toner supplied onto the roller 67 enters between the pressing portion of the layer thickness regulating blade 68 and the developing roller 67, where it is further sufficiently frictionally charged to have a constant thickness. It is carried on the developing roller 67 as a book layer.

  The photosensitive drum 62 is rotatably disposed at a side position of the developing roller 67 so as to face the developing roller 67. The photosensitive drum 62 is formed of a positively chargeable photosensitive layer having a drum main body grounded and a surface portion formed of a polycarbonate or the like.

  The scorotron charger 64 is disposed above the photosensitive drum 62 at a predetermined interval so as not to contact the photosensitive drum 62. The scorotron charger 64 is a positively charged scorotron charger that generates corona discharge from a charging wire such as tungsten, and is configured to uniformly charge the surface of the photosensitive drum 62 to a positive polarity. ing.

  The surface of the photosensitive drum 62 is positively charged like a scorotron charger 64 and then exposed by high-speed scanning of laser light from the scanner unit 16, and an electrostatic latent image based on predetermined image data is generated. It is formed. Next, the electrostatic latent image formed on the surface of the photosensitive drum 62 when the toner carried on the developing roller 67 and positively charged comes into contact with the photosensitive drum 62 by the rotation of the developing roller 67. That is, the surface of the photosensitive drum 62 that is uniformly positively charged is supplied to an exposed portion that is exposed to a laser beam and the potential is lowered, and is selectively carried to be visualized. By means of this, reversal development is achieved.

  The transfer roller 65 is disposed below the photosensitive drum 62 so as to face the photosensitive drum 62, and is rotatably supported by the drum cartridge 61. The transfer roller 65 is covered with a roller made of an elastic body in which an ionic substance such as lithium perchlorate is added to a metal roller shaft. According to the transfer roller 62, the sheet α can be favorably conveyed while the electrostatic latent image formed on the photosensitive drum 62 is transferred to the sheet α.

  The transfer roller 65 is configured such that a predetermined transfer bias is applied to the photosensitive drum 62 by a transfer bias application circuit (not shown) during transfer. Therefore, the visible image carried on the surface of the photosensitive drum 62 is transferred to the sheet α while the sheet α passes between the photosensitive drum 62 and the transfer roller 65 so as to face the transfer roller 65. .

  The conductive brush 66 is provided in contact with the surface of the photosensitive drum 62 on the downstream side of the transfer roller 65 in the rotation direction of the photosensitive drum 62 and on the upstream side of the scorotron charger 64. The conductive brush 66 removes paper dust adhering to the surface of the photosensitive drum 62 after transfer.

  As shown in FIG. 1, the fixing unit 80 is disposed on the downstream side of the process unit 60, and includes a heating roller 81, a pressing roller 82 that presses the heating roller 81, and the heating roller 81 and the pressing roller 82. A conveyance roller 83 provided on the downstream side is provided. The heating roller 81 is made of metal and includes a halogen lamp for heating. In the fixing unit 80, the toner transferred on the paper α in the process unit 60 is heated on the paper α while the paper α passes between the heating roller 81 and the pressure roller 82 by heat generated from the halogen lamp. Then, the paper α is transported to the paper discharge unit 9 by the transport roller 83. The transport roller 83 includes a pair of small rollers 83a and 83b installed in parallel in the axial direction, and a large roller 83c provided to face the small rollers 83a and 83b. The paper α is passed between the small rollers 83a and 83b and the large roller 83c and conveyed to the paper discharge unit 9 side.

  The paper discharge unit 9 includes a pair of paper discharge rollers 92 installed in the paper discharge unit 90, and the paper α is discharged onto the paper discharge tray 11 by the paper discharge rollers 92. The paper discharge unit 9 includes a paper discharge sensor 96 on the downstream side of the paper discharge roller 92, and the paper discharge sensor 96 discharges the paper α from the paper discharge roller 92 onto the paper discharge tray 11. It is for detecting whether or not.

  In addition, the laser printer 1 is provided with a reverse conveyance unit 20 in order to form images on both sides of the paper α. The reverse conveyance unit 20 includes the paper discharge roller 92, the reverse conveyance path 22, the reverse conveyance roller 24, and the flapper 26 described above.

  The paper discharge roller 92 includes a pair of rollers and is configured to be able to switch between forward rotation and reverse rotation. As described above, the paper discharge roller 92 rotates in the forward direction when the paper α is discharged onto the paper discharge tray 11, but rotates in the reverse direction when the paper α is reversed.

  The reverse conveyance path 22 passes through the outer periphery of the fixing unit 80 so that the sheet α can be conveyed from the paper discharge roller 92 to the reverse conveyance roller 24 disposed below the image forming unit 5. The upstream end is disposed near the paper discharge roller 92, and the downstream end is disposed near the reverse conveying roller 24.

The reverse conveyance roller 24 is provided near the paper feed roller 32 at the downstream end of the reverse conveyance path 22.
The flapper 26 is provided so as to face a branch portion between the paper discharge path 85 and the reverse conveyance path 22, and is formed so that the reversed paper α is not sent to the paper discharge path 85 side.

  Further, on the downstream side of the reverse conveying roller 24, a re-sending path 28 through which the paper α sent from the reverse conveying roller 24 passes above the paper supply roller 32 and the registration roller 34 and is conveyed to the registration roller 35. Is formed.

  When images are formed on both sides of the paper α, the reverse conveyance unit 20 operates as follows. That is, when the sheet α having an image formed on one surface is sent from the sheet discharge path 85 to the sheet discharge roller 92 by the transport roller 83, the sheet discharge roller 92 rotates forward with the sheet α interposed therebetween. When the paper α is once transported outward (discharge tray 11 side), most of the paper α is sent to the outer side, and the rear end of the paper α is sandwiched between the paper discharge rollers 92, it rotates forward. To stop. Next, the paper discharge roller 92 rotates in the reverse direction, and the paper α is conveyed to the reverse conveyance roller 24 via the reverse conveyance path 22 and further sent to the registration roller 35 via the retransmission insertion path 28. The sheet α conveyed to the registration roller 35 is turned over and sent again to the image forming unit 5 after a predetermined registration, whereby a predetermined image is formed on both sides of the sheet α.

  Further, in this laser printer 1, the toner remaining on the surface of the photosensitive drum 62 after being transferred to the paper α by the transfer roller 65 is recovered by the developing roller 67, so that the residual toner is recovered by a so-called cleanerless system. ing. If the toner remaining on the photosensitive drum 62 is collected by such a cleaner-less method, there is no need to provide a cleaning device such as a blade or a storage unit for waste toner, so that the configuration of the device is simplified, the size is reduced, and the cost is reduced. Can be achieved.

Next, the paper discharge tray 11 of this embodiment will be described.
As shown in FIG. 1, the paper discharge tray 11 of the laser printer 1 of the present embodiment is formed in a shape in which the upper surface of the main body casing 10 is dug down. The cross section is formed in a substantially triangular shape so as to have the same height as the upper surface of the main casing 10.

  The wall surface 12 on one end side of the discharge tray 11 forms a surface orthogonal to the horizontal plane. Hereinafter, this wall surface is referred to as a sheet rear end contact surface 12. A paper discharge roller 92 is provided at the upper end of the sheet rear end contact surface 12, and a paper discharge sensor 96 is provided in front of it.

  The bottom surface 13 of the paper discharge tray 11 is directed from the lower end of the paper rear end contact surface 12 toward the other end side of the paper discharge tray 11, that is, downstream of the paper α discharged from the paper discharge roller 92 in the paper discharge direction. It is formed in a shape that is inclined obliquely upward and reaches the upper surface of the main body casing 10. On the back side of the bottom surface 13 (inside the main body casing 10), the above-described scanner unit 50 is disposed along the bottom surface 13.

Side surfaces 14 on the left and right sides of the bottom surface 13 (both sides in the left-right direction perpendicular to the paper discharge direction) are formed perpendicular to the bottom surface 13.
Moreover, the upper surface of the main body casing 10 on the other end side of the bottom surface 13 is provided with a lid portion 15 that is rotatably attached. The lid portion 15 is formed in a size that covers the entire portion where the paper discharge tray 11 is open with respect to the upper surface of the main body casing 10, and closes the paper discharge tray 11 when moved to the closed position. When moved to the open position, an inclined surface is formed which is continuous with the bottom surface 13 and extends upward from the upper surface of the main body casing 10 toward the downstream side in the paper discharge direction.

Further, the paper discharge tray 11 includes a replacement adapter 16 as a convex portion that can be placed on the bottom surface 13.
The replacement adapter 16 is configured to be detachable from the bottom surface 13. The replacement adapter 16 is formed to have a size that covers the bottom surface 13. When the replacement adapter 16 is installed on the bottom surface 13, the paper rear end abutting surface 12 that is one end on the upstream side of the paper discharge roller 92 in the paper discharge direction. A curved mounting surface 17 having a convex portion 16b swelled upward is formed between the lower end of the sheet and the other end that is the downstream side of the sheet discharge roller 92 in the sheet discharge direction.

  Specifically, when the replacement adapter 16 is placed on the bottom surface 13, the surface on one end side from the top portion 16c of the convex portion 16b is 30 ° above the one end side in the horizontal direction. (Θ = 30 ° in FIG. 2), and the surface on the other end side of the top portion 16c of the convex portion 16b is placed on the paper α in the paper discharge direction when the paper α is placed. It is formed so as to form an angle with a horizontal plane as long as it does not move due to its own weight.

  Further, the replacement adapter 16 is formed with a width wider than the paper width in the left-right direction (direction perpendicular to the paper surface of FIG. 1) perpendicular to the paper discharge direction, and the convex portion 16b is also larger than the paper width. The paper is formed in a wide width, and the length from one end on the paper discharge roller 92 side to the top 16c of the convex portion 16b (corresponding to r in FIG. (In this embodiment, the length in the vertical direction of A4 size paper) is half the length.

  Next, a specific example of the replacement adapter 16 is as described above. However, since the shape of the replacement adapter 16 in which the shape of the replacement adapter 16 does not generate a cylinder by changing its shape in various ways will be described below. To do.

  Here, FIG. 3 is an r-θ graph showing the relationship of r-θ in FIG. FIG. 3 is a graph showing the state of the sheet when the distance r and the angle θ are variously changed and the sheet is placed on the placement surface 17 of the replacement adapter 16.

As shown in FIG. 2, the angle at which the surface on one end side from the top portion 16c of the convex portion 16b of the replacement adapter 16 placed on the bottom surface 13 is inclined upward from the one end side with respect to the horizontal direction. The replacement adapter 16 was manufactured by changing θ and the distance r from one end of the replacement adapter 16 to the top 16c of the convex portion 16b as parameters. The paper used in the experiment is A4 size 80 g / m ² paper called DATA COPY (trade name) manufactured by Modo and RECYCLING COPY (trade name) manufactured by STEINBEIS.

  As a result, as shown in FIG. 3, the replacement adapter 16 designed with parameters within the range of the outermost graph (the graph surrounded by the points a to e) is full of the allowable loading capacity although the cylinder curl occurs. Sheets of paper could be stacked on the tray 11.

  The replacement adapter 16 designed with parameters in the middle of the graph (the graph surrounded by the points f to k) can stack sheets of full stackable capacity on the tray 11 although light cylinder curl occurs. did it.

  The replacement adapter 16 designed with the parameters within the range of the inner graph (the graph surrounded by the points 1 to p) does not cause any cylinder curl and can stack a sheet of a stackable amount on the tray 11. did it.

The replacement adapter 16 designed with parameters not surrounded by these causes cylinder curl, and paper cannot be stacked on the tray 11 to the full load capacity.
The distance r and the angle θ of each point are represented by (r, θ) in the coordinate format, a (60, 55), b (60, 50), C (110, 20), d (155, 20), e (155, 50), f (80, 50), g (80, 45), h (112, 27), i (150, 27), j (152, 37), k (130, 40), l (105, 40), m (122, 33), n (145, 33), o (145, 34), p (122, 35).

  As can be seen from the graph of FIG. 3, the angle θ is preferably 20 ° or more and 55 ° or less (point a, point c), and is inclined at an angle in the range of 27 ° or more and 55 ° or less. Are more preferable (point h, point f), and most preferably 33 ° to 40 ° (point l, point m). The distance r is preferably 60 mm (20%) or more and 155 mm (52%) or less (point a, point d), more preferably 80 mm (27%) or more and 152 mm (51%) or less ( Most preferably, the point f and the point j) are 105 mm (35%) or more and 145 mm (49%) or less (point l, point n). Note that% display is a ratio to the vertical length (297 mm) of A4 size paper.

  Further, the angle formed between the surface (reference A) on the one end side from the top 16c of the convex portion 16b and the surface (reference B) on the other end side from the top 16c is in the range of 120 ° to 165 °. It is preferable that it is comprised. More preferably, it is configured to be within a range of 130 ° to 150 °.

When the laser printer 1 described above is used, the following operations and effects are obtained.
When the paper α is placed on the placement surface 17 of the laser printer 1 described above, the paper α is placed in a state in which the middle of the paper α is raised upward when viewed in a section along the paper discharge direction. For this reason, the sheet is restricted from being displaced inward at the edge in the left-right direction perpendicular to the sheet discharge direction, thereby preventing the above-described cylinder curl from occurring. Therefore, the laser printer 1 according to the present embodiment does not cause a cylindrical curl, so that more paper α can be placed on the paper discharge tray 11 than a conventional laser printer having a paper discharge tray of the same depth. it can. Therefore, when manufacturing a laser printer capable of placing the same number of sheets α on the paper discharge tray 11, the laser printer 1 of the present embodiment has a shallower discharge than a conventional laser printer in which cylindrical curling occurs. Since the paper tray 11 may be formed, the entire apparatus can be reduced in size.

  Next, the length r from one end on the paper discharge roller 92 side to the top 16c of the convex portion 16b is formed to be approximately half the length of the paper α in the paper discharge direction (vertical direction in the present embodiment). Therefore, the occurrence of cylinder curl can be effectively suppressed. From the above consideration, the length from one end on the paper discharge roller 92 side to the top 16c of the convex portion 16b is preferably 40 to 60% of the length of the paper α in the paper discharge direction. More preferably, the length is 45% to 55%.

  Next, the surface on the other end side from the top portion 16c of the convex portion 16b (symbol B) and the upper surface of the main body casing 10 connected to this surface (symbol B) (upper surface further downstream from the lid 15: symbol C) When the paper α is placed, the paper α is preferably formed so as to form an angle with the horizontal plane in a range in which the paper α moves by its own weight in the paper discharge direction and does not fall from the placement surface 17. In this way, the paper α can be placed on the placement surface 17 without dropping from the other end side of the placement surface 17. The convex portion 16b has an angle between a surface (reference A) on one end side from the top portion 16c of the convex portion 16b and a surface (reference symbol B) on the other end side from the top portion 16c of 120 ° or more and 165 °. It is preferable to configure so as to be within the following range. When configured within an angle within this range, tube curling is particularly difficult to occur.

  Next, when the replacement adapter 16 places a sheet on the placement surface 17 described above, the sheet α bends in accordance with the shape of the convex portion 16b until at least 100 sheets α are stacked. Therefore, the sheet α bends in accordance with the shape of the convex portion up to at least 100 sheets, so that the sheet α can be placed on the placement surface 17 so that the sheet α does not shift in the sheet discharge direction.

Next, since the paper rear end contact surface 12 orthogonal to the horizontal plane is provided on one end side of the placement surface 17, the paper α is placed on the placement surface 17 following the paper rear end contact surface 12. Can be placed.
Next, since the convex portion 16b is provided with a width wider than the paper width in the paper width direction orthogonal to the paper discharge direction, even if the paper α is displaced in the paper width direction, the shape of the convex portion 16b. The paper α can be placed on the placement surface 17 according to the above.

  Next, although the replacement adapter 16 is of A4 size, if a replacement adapter for other sizes is formed, sheets of other sizes can be stacked on the tray 11 without the occurrence of cylinder curl. . In addition, the laser printer 1 according to the present embodiment includes the replacement adapter 16, so that the heat of various devices provided in the main body casing 10 is not easily transmitted to the paper. Therefore, in the laser printer 1 of the present embodiment, it is possible to prevent the occurrence of cylinder curl due to this heat.

The embodiment of the present invention is not limited to the above-described embodiment, and it goes without saying that various forms can be adopted as long as it belongs to the technical scope of the present invention.
For example, a sheet pressing member that comes into contact with the sheet α on the downstream side of the sheet discharge roller 92 in the sheet discharge direction may be provided. If this paper pressing member is provided, it is possible to prevent the paper placed on the placement surface 14 from being displaced from the placement surface 17 and falling off the placement surface 17.

  In the above embodiment, the laser printer 1 including the replacement adapter 16 has been described. However, as illustrated in FIG. 4, the second bottom surface 13 a is formed on the bottom surface 13 along the mounting surface 17 described in FIG. 1. It may be formed. At this time, it is preferable that a space is formed between the bottom surface 13 and the second bottom surface 13a. With such a configuration, the heat in the main body casing 10 becomes difficult to be transmitted to the second bottom surface 13a, and as a result, the heat is hardly transmitted to the paper α, so that the occurrence of cylinder curl is prevented more effectively. Because it can. The space between the bottom surface 13 and the second bottom surface 13a is more preferably a vacuum.

Furthermore, although the example provided with the bottom face 13 and the second bottom face 13a has been described in FIG. 4, as shown in FIG. 5, the second bottom face 13a may be provided only.
Furthermore, in the above-described embodiment, the replacement adapter 16 having such a shape that the mounting surface 17 draws a substantially parabolic cross section has been described. However, as illustrated in FIG. 6, the replacement adapter 16 may be formed in a triangular cross section.

It is a sectional side view showing one embodiment of a laser printer. It is a schematic diagram of a laser printer and is explanatory drawing for demonstrating r and (theta). It is an r-θ graph. It is a sectional side view of the modification of this embodiment. It is a sectional side view of the modification of this embodiment. It is a sectional side view of the modification of this embodiment. It is a sectional side view of the conventional modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Laser printer, 3 ... Feeder part, 5 ... Image forming part, 9 ... Paper discharge part, 10 ... Main body casing, 11 ... Paper discharge tray, 12 ... Paper rear end contact surface, 13 ... Bottom surface, 13a ... Bottom surface , 14 ... side face, 15 ... lid part, 16 ... scanner unit, 16 ... replacement adapter, 16b ... convex part, 16c ... top part, 17 ... mounting surface, 20 ... reverse transfer part, 22 ... reverse transfer path, 24 ... Reverse conveying roller 26. Flapper 28. Retransmission pass 30. Paper feed tray 31 31 Paper pressing plate 32 Paper feed roller 33 Paper feed pad 34 Register roller 35 Register roller 36 ... Paper dust removing roller, 37 ... Registration roller, 40 ... Multi-purpose tray, 41 ... Multi-purpose feeding roller, 42 ... Multi-bar feeding sheet, 42 ... Multi-purpose feeding pad, 50 ... Scanner Knit, 51 ... Polygon mirror, 52 ... fθ lens, 53 ... Cylinder lens, 54-56 ... Reflector, 60 ... Process unit, 61 ... Drum cartridge, 62 ... Transfer roller, 63 ... Developer cartridge, 64 ... Scorotron charger , 65 ... transfer roller, 66 ... conductive brush, 67 ... photosensitive drum, 67 ... developing roller, 68 ... layer thickness regulating blade, 68a ... pressing part, 69 ... supply roller, 70 ... toner box, 71 ... rotating shaft, 72 ... Agitator 73 ... Toner supply port 73 ... Developing cartridge 80 ... Fixing unit 81 ... Heating roller 82 ... Pressing roller 83 ... Conveying roller 83a, 83b ... Small roller 83c ... Large roller 85 ... Discharge Pass 92 discharge roller 96 discharge sensor 96

Claims (11)

A placement surface on which a sheet-like recording medium can be placed is formed on the upper surface of the housing of the apparatus main body, and the recording medium on which an image is formed by the image forming unit in the housing is discharged onto the stacking surface. An image forming apparatus configured such that one end of the mounting surface is disposed below the paper roller,
The mounting surface described above is
Between the one end and the other end on the upstream side in the paper discharge direction of the paper discharge roller, having a convex portion raised upward,
The image forming apparatus, wherein the surface on one end side from the top of the convex portion is inclined at an angle in a range of 25 ° to 55 ° above the one end side with respect to a horizontal direction. The length from the one end on the paper discharge roller side to the top of the convex portion is formed to be approximately half the length of the recording medium in the paper discharge direction. The image forming apparatus according to 1. An image forming apparatus, wherein the mounting surface is formed to have a size capable of mounting the recording medium of A4 size. The surface on the other end side from the top of the convex portion and the upper surface of the housing of the apparatus main body connected to the surface are arranged so that the recording medium is in the paper discharge direction when the recording medium is placed. 4. The image forming apparatus according to claim 1, wherein the image forming apparatus is formed so as to form an angle with a horizontal plane within a range in which it moves by its own weight and does not fall from the placement surface. 5. The convex portion is configured such that an angle formed between the surface on the one end side from the top of the convex portion and the surface on the other end side from the top is in a range of 120 ° to 165 °. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. 2. The mounting surface according to claim 1, wherein the mounting surface is formed in a shape in which the recording medium bends in accordance with the shape of the convex portion until at least 100 recording media are stacked. The image forming apparatus according to claim 5. The image forming apparatus according to claim 1, wherein the one end of the placement surface has a sheet rear end contact surface orthogonal to a horizontal plane. The image forming apparatus according to claim 1, further comprising a sheet pressing member that comes into contact with the recording medium downstream of the sheet discharge roller in the sheet discharge direction from above. 9. The convex portion according to claim 1, wherein the convex portion is provided with a width wider than a paper length in the same direction as the left-right direction with respect to a left-right direction perpendicular to the paper discharge direction. Image forming apparatus. The housing includes a main body case that forms a main body portion of the housing, and a convex portion that is configured by a member different from the main body case.
The image forming apparatus according to claim 1, wherein the convex portion has the convex portion placed on an upper surface of a main body case. The image forming apparatus according to claim 1, wherein the convex portion is configured to be detachable from an upper surface of the main body case.

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