JP4306516B2 - Image forming apparatus - Google Patents

Description

The present invention relates to an image forming apparatus .

2. Description of the Related Art Conventionally, there has been provided an image forming apparatus such as a laser printer in which a transfer roller is detachably attached to an apparatus main body. The transfer roller is usually mounted in the main body of the image forming apparatus while being rotatably held by a bearing. However, in order to be able to easily handle maintenance, replacement, etc., the transfer roller is required to be easily attached and detached. It has been.
Japanese Patent Laid-Open No. 07-168510

  By the way, although the transfer roller is disposed inside the image forming apparatus, access to the transfer roller becomes a problem when trying to reduce the size of the apparatus. That is, an image carrier and a paper guide for transporting paper are present in the vicinity of the transfer roller. However, in order to reduce the size of the entire apparatus, these must be arranged closer to each other. As a result, an operation space for operating the transfer roller cannot be secured. On the other hand, Patent Document 1 discloses a technique for forming a transfer roller and a registration roller pair as one unit. According to this technology, since the transfer roller and the registration roller pair can be handled integrally, the handling property is improved. However, an operator is required for the transfer roller arranged at the internal position (particularly the recessed position) of the image forming apparatus. However, it has not been possible to solve the problem of how to access from the outside and how to attach and detach, and a configuration in which the transfer roller can be easily and easily attached and detached from the apparatus main body is still desired.

  The present invention has been made based on the above circumstances, and an object thereof is to provide a configuration in which a transfer roller can be easily attached to and detached from an apparatus main body.

As means for achieving the above-mentioned object, the invention of claim 1 includes a process cartridge provided with an image carrier and a storage portion for storing the process cartridge, and an opening communicating with the storage portion is at one end. An image forming apparatus comprising: an apparatus main body portion formed on a side; a transfer roller having a roller portion disposed to face the image carrier and a shaft member that holds the roller portion; The transfer roller is rotatably held, and a base part mounted on the apparatus main body part and the base part are slid in a direction substantially orthogonal to the axial direction of the shaft member with respect to the apparatus main body part. comprising a slide mechanism to withdraw to the opening side, wherein the base unit includes a mounting means for mounting the process cartridge detachably, in a state of mounting the process cartridge The serial sliding mechanism, characterized in that it is configured to slidably.

According to a second aspect of the invention, in the image forming apparatus according to claim 1, in the lower of the base portion, the paper cassette is provided for housing the paper, the paper cassette, so as to be drawable to the opening side It is attached to the apparatus main body.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect , the base portion is provided with a paper guide portion that supports the paper and guides it to the transfer roller. To do.

According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, a paper support inclined surface that is inclined so as to become higher toward the transfer roller side at an end portion of the paper guide portion on the transfer roller side. The transfer roller is formed and held by the base portion so that the entire transfer roller is positioned below the upper end portion of the sheet supporting inclined surface.

According to a fifth aspect of the present invention, in the image forming apparatus according to the third or fourth aspect , the paper guide portion cantilevered from the end on the transfer roller side to the transfer roller side. A flexible paper support member for supporting paper is provided, and the transfer roller is held by the base portion so as to be positioned below the upper end of the paper support member. To do.

A sixth aspect of the present invention is the image forming apparatus according to any one of the first to fifth aspects, further comprising positioning means for positioning the base portion and the apparatus main body portion.

According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the base portion is slid by the slide mechanism until the transfer roller is positioned outside the apparatus main body portion. It is configured to be possible.

According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to seventh aspects, the base portion is configured to be removable from the apparatus main body.

A ninth aspect of the present invention is the image forming apparatus according to any one of the first to eighth aspects, wherein the shaft member of the transfer roller is a gear for transmitting power from the outside to the transfer roller. A member is provided.

According to a tenth aspect of the present invention, in the image forming apparatus according to any one of the first to eighth aspects, a sheet is sandwiched between the transfer roller and the image carrier, and the image carrier is rotated to rotate the image carrier. The transfer roller is configured to rotate in conjunction with the movement of the sheet by a frictional force generated between the transfer roller and the sheet.

According to an eleventh aspect of the present invention, in the image forming apparatus according to any one of the first to tenth aspects, a registration roller is rotatably provided on the base portion.

According to a twelfth aspect of the present invention, in the image forming apparatus according to any one of the first to eleventh aspects, the image forming apparatus directs a sheet fed from one end side in the longitudinal direction of the sheet feeding cassette toward the other end side. The first direction changing portion that changes the direction and sends it to the transfer roller side disposed above the sheet feeding cassette, and changes the direction of the sheet that has passed through the transfer roller toward the one end side, and And a second direction changing section that feeds the sheet discharge section disposed above the transfer roller.

According to a thirteenth aspect of the present invention, in the image forming apparatus according to any one of the first to twelfth aspects, the transfer roller is exposed to the accommodating portion side in a state where the process cartridge is removed from the main body of the device. It is comprised so that it may be comprised.

<Invention of Claim 1>
In this way, the transfer roller can be pulled out to the opening side by the sliding operation of the base portion, and the transfer roller can be easily maintained.

Furthermore, according to this configuration, the process cartridge and the base portion can be pulled out together. In particular, this configuration is advantageous when performing maintenance of both the process cartridge and the transfer roller at the same time.

<Invention of Claim 2 >
In this way, the process cartridge, the base portion, and the paper cassette can all be operated from the same side (that is, the side provided with the opening), so that the operability is further enhanced.

<Invention of Claim 3 >
As described above, if the transfer roller and the sheet guide portion for guiding the sheet to the transfer roller are integrated as a unit, the base portion can be slidable and can be advantageously reduced in size.

<Invention of Claim 4 >
In this way, an inclined sheet supporting inclined surface that becomes higher toward the transfer roller side is formed and the entire transfer roller is positioned below the upper end of the sheet supporting inclined surface. Therefore, it is more effective to apply the above configuration in which the base portion is slid to such a configuration.

<Invention of Claim 5 >
In such a configuration in which the entire transfer roller is positioned below the upper end of the sheet support member, the sheet support member becomes an obstacle and it is difficult to access the transfer roller. It is more effective to apply the above-described configuration to slide.

<Invention of Claim 6 >
If it does in this way, a base part can be stably positioned to a device main part.

<Invention of Claim 7 >
According to this configuration, since the transfer roller can be slid until it reaches the position outside the apparatus main body, the transfer roller can be accessed outside the apparatus main body, so that it is difficult to restrict space and is easy to operate. The device configuration is high.

<Invention of Claim 8 >
If it does in this way, a base part can be removed from an apparatus main-body part and can be handled freely, and it will become the structure which is easier to operate a base part.

<Invention of Claim 9 >
In this way, a suitable configuration can be obtained in which a driving force can be transmitted from the outside to the transfer roller mounted on the base portion.

<Invention of Claim 10 >
According to this configuration, the transfer roller can be driven, and a power transmission member such as a gear member can be omitted to simplify the configuration.

<Invention of Claim 11 >
In this way, the registration roller and the transfer roller can be integrated into a unit, which is advantageous for downsizing.

<Invention of Claim 12 >
According to this configuration, the apparatus can be reduced in size, and on the other hand, the transfer roller can be easily detached by operating the base member, so that it is difficult to remove the transfer roller due to the downsizing of the apparatus. This is an effective configuration.

<Invention of Claim 13 >
With this configuration, the transfer roller can be maintained using the housing portion that houses the process cartridge separately from the slide operation of the base member or together with the slide operation of the base member.

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS.
1. Configuration of the Present Embodiment FIG. 1 is a side sectional view of an essential part showing an embodiment of a laser printer as an image forming apparatus of the present invention. In FIG. 1, a laser printer 1 includes a feeder unit 4 for feeding a sheet as a recording medium in a main body casing 2, an image forming unit 5 for forming a predetermined image on the fed sheet, and the like. It has.

(1) Configuration of Feeder Unit The feeder unit 4 includes a paper feed cassette 43 that is detachably attached to the bottom of the main body casing 2, a paper pressing plate 6 provided in the paper feed cassette 43, and a paper feed cassette. The paper feed roller 7 and the paper feed pad 8 provided above one end of the paper 43, the transport roller 59 provided on the downstream side in the paper transport direction with respect to the paper feed roller 7, and the paper with respect to the transport roller 59 And a registration roller 9 provided on the downstream side in the conveying direction.

  The sheet pressing plate 6 can stack sheets in a stacked manner, and an end far from the sheet feeding roller 7 is supported so as to be swingable, and a near end is rotatable in the vertical direction. Moreover, it is urged | biased upwards by the spring which is not shown in figure from the back side. Therefore, the sheet pressing plate 6 is rotated downward against the urging force of the spring, with the end portion far from the sheet feeding roller 7 as a fulcrum as the amount of stacked sheets increases. The paper feed roller 7 and the paper feed pad 8 are arranged to face each other, and the paper feed pad 8 is pressed toward the paper feed roller 7 by a spring 10 provided on the back side of the paper feed pad 8. .

  The uppermost sheet on the sheet pressing plate 6 is pressed toward the sheet feeding roller 7 by a spring (not shown) from the back side of the sheet pressing plate 6, and the sheet feeding roller 7 and the sheet feeding pad are rotated by the rotation of the sheet feeding roller 7. After being sandwiched between 8, the paper is fed one by one. The fed sheet is guided by the guide unit 61 so as to be folded back to the side opposite to the fed sheet side, and further fed to the registration roller 9 by the conveying roller 59. The registration roller 9 is composed of two rollers, a driving roller 44 and a driven roller 45 provided in the base portion, respectively, and the sheet sent from the conveying roller 59 is sandwiched between the driving roller 44 and the driven roller 45. After a predetermined registration, the image is sent to the image forming unit 5. In this embodiment, the guide part 61 and the conveyance roller 59 correspond to a first direction changing part. As a result, the direction of the sheet fed from one end side (front side) in the longitudinal direction of the sheet feed cassette 43 is changed toward the other end side (rear side) and sent to the transfer roller 26 side.

(2) Configuration of Image Forming Unit The image forming unit 5 includes a scanner unit 11, a process unit 12 as a process cartridge referred to in the claims, a fixing unit 13, and the like.

(A) Configuration of Scanner Unit The scanner unit 11 is provided in the upper part in the main body casing 2, and includes a laser light emitting unit (not shown), a polygon mirror 14 that is driven to rotate, lenses 15 and 16, and reflecting mirrors 17 and 18. , 19, and the like, and a polygon beam 14, a lens 15, reflecting mirrors 17 and 18, a lens 16, and a reflecting mirror 19, as indicated by a chain line, a laser beam based on predetermined image data emitted from the laser emitting section. Are passed or reflected in this order to irradiate the surface of the photosensitive drum 21 of the process unit 12 described later by high-speed scanning. In the present embodiment, the photosensitive drum 21 corresponds to an image carrier in the claims.

(B) Configuration of Process Unit Next, the process unit 12 will be described with reference to FIG.
FIG. 2 is an enlarged side sectional view showing the process unit 12. In the figure, a process unit 12 is disposed below the scanner unit 11 and is detachably mounted on the main body casing 2, and a photosensitive drum 21, a developing cartridge 36, and a scorotron charger 25. Etc. The developing cartridge 36 is detachably attached to the drum cartridge 20 and includes a developing roller 22, a layer thickness regulating blade 23, a supply roller 24, a toner box 27, and the like.

  The toner box 27 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.

  The toner in the toner box 27 is agitated by an agitator 29 supported by a rotating shaft 28 provided at the center of the toner box 27 and discharged from a toner supply port 30 opened at a side portion of the toner box 27. . Note that a toner remaining amount detection window 40 is provided on the side wall of the toner box 27 and is cleaned by a cleaner 39 supported by the rotary shaft 28.

  A supply roller 24 is disposed at a side position of the toner supply port 30 so as to be rotatable in the direction of the arrow (counterclockwise), and the developing roller 22 faces the supply roller 24 in the direction of the arrow ( It is arranged to be rotatable counterclockwise. The supply roller 24 and the developing roller 22 are in contact with each other in a state where each of them is compressed to some extent.

  The supply roller 24 has a metal roller shaft covered with a roller made of a conductive foam material. The developing roller 22 has a metal roller shaft covered with a roller made of a conductive rubber material. More specifically, the roller portion of the developing roller 22 has a urethane rubber or silicone rubber coating layer containing fluorine on the surface of a roller body made of conductive urethane rubber or silicone rubber containing carbon fine particles. It is covered. A predetermined developing bias is applied to the developing roller 22 with respect to the photosensitive drum 21.

  In addition, a layer thickness regulating blade 23 is disposed in the vicinity of the developing roller 22. The layer thickness regulating blade 23 includes a blade body 37 made of a metal leaf spring material, and a pressing portion 38 having a semicircular cross section made of an insulating silicone rubber provided at the tip of the blade body 37. The end of the blade body 37 opposite to the pressing portion 38 is supported by the developing cartridge 36 near the developing roller 22, and the pressing portion 38 is pressed against the developing roller 22 by the elastic force of the blade body 37. It is configured as follows.

  The toner discharged from the toner supply port 30 is supplied to the developing roller 22 by the rotation of the supplying roller 24. At this time, the toner is positively frictionally charged between the supplying roller 24 and the developing roller 22, and further developed. As the developing roller 22 rotates, the toner supplied onto the roller 22 enters between the pressing portion 38 of the layer thickness regulating blade 23 and the developing roller 22, where the toner is more sufficiently frictionally charged and constant. It is carried on the developing roller 22 as a thin layer.

  The photosensitive drum 21 is disposed at a side position of the developing roller 22 so as to be rotatable in the arrow direction (clockwise) in a state of facing the developing roller 22 with a predetermined interval. The photosensitive drum 21 is formed of a positively chargeable photosensitive layer having a drum body grounded and a surface portion made of polycarbonate or the like.

  The scorotron charger 25 is disposed above the photosensitive drum 21 at a predetermined interval so as not to contact the photosensitive drum 21. The scorotron charger 25 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 21 to a positive polarity. ing.

  The surface of the photosensitive drum 21 is uniformly positively charged by the scorotron charger 25 and then exposed by high-speed scanning of the laser beam from the scanner unit 11 to form an electrostatic latent image based on predetermined image data. Is done. Next, the electrostatic latent image formed on the surface of the photosensitive drum 21 when the positively charged toner carried on the developing roller 22 comes into contact with the photosensitive drum 21 by the rotation of the developing roller 22. That is, the surface of the photosensitive drum 21 that is uniformly positively charged is supplied to a portion of the photosensitive drum 21 that is exposed to a laser beam and the potential of which is lowered, and is selectively carried to be visualized. Development is achieved.

(C) Configuration of Transfer Roller Next, the configuration of the transfer roller and its vicinity will be described.
As shown in FIG. 4, the transfer roller 26 according to the present embodiment holds a roller portion 26 a disposed opposite to the photosensitive drum 21 (see FIG. 1) corresponding to an image carrier, and the roller portion 26 a. The shaft member 26b is configured to be detachably attached to the base portion 200. The base part 200 is configured to hold the transfer roller 26 in a rotatable manner and to be mounted on the apparatus main body 1a. The base part 200 supports both ends of the shaft member 26b in order to hold the transfer roller 26. A pair of bearing portions 80 and 80 are provided. Each of the bearing portions 80 has a structure in which a slit 80a is formed on the photosensitive drum 21 side, and the shaft member 26b can be detached in a direction perpendicular to the axial direction through the slit 80a.

  In the present embodiment, as shown in FIG. 3, the base portion 200 is configured to be slidable toward the opening 74. Specifically, the side conceptual diagram of FIG. 8 and the front conceptual diagram of FIG. A slide mechanism for sliding the base portion 200 is provided so as to briefly explain the state where the portion 74 is opened conceptually (front cover 65 (FIG. 1 is omitted)). This slide mechanism is configured to slide in the direction substantially perpendicular to the axial direction of the shaft member 26b with respect to the apparatus main body 1a and to be drawn out toward the opening 74, and is formed on the apparatus main body 1a side. The guide groove 77 and the guided portion 203 formed in the base portion 200 are configured. The guide groove 77 is formed along a direction substantially orthogonal to the axial direction of the shaft member 26 b, and a pair of guided portions formed so as to protrude sideways in the base portion 200. By moving 203, the base part 200 slides back and forth.

  The base unit 200 is configured to be movable relative to the apparatus main body 1a and the process unit 12, and is configured to be slidable until the transfer roller 26 is positioned outside the apparatus main body 1a by a slide mechanism. Has been. That is, the base portion 200 slides until at least the entire transfer roller 26 is positioned further forward than the front end portion 1b of the apparatus main body portion 1a. In the present embodiment, the base unit 200 moves until the entire base unit 200 is completely exposed to the outside, and is configured to be removable from the apparatus main body unit 1a. Further, as shown in FIG. 8, a stopper 78 is provided for positioning the base 200 and the apparatus main body 1a in a state where the base 200 is accommodated in the apparatus main body 1a. (This stopper 78 corresponds to the positioning means in the claims).

  Returning to FIG. 4, a gear member 82 for transmitting power from the outside to the transfer roller 26 is provided at the end of the shaft member 26 b of the transfer roller 26. The gear member 82 is rotated by being driven by the apparatus main body 1a or another gear member provided in the process unit 12. In addition, although the structure which transmits a driving force via the gear member 82 was illustrated here, it is good also as a structure which does not provide the gear member 82. FIG. The sheet is sandwiched between the transfer roller 26 and the photosensitive drum 21, and the sheet is moved by the rotation of the photosensitive drum 21. The transfer roller 26 moves the sheet by a frictional force generated between the transfer roller 26 and the front sheet. You may make it rotate in conjunction with.

  In the present embodiment, as shown in FIG. 3, an opening 74 is formed on one end side of the apparatus main body 1 a, and an accommodation section 70 is formed in communication with the opening 74. In a state where it is removed from the portion 1a, the transfer roller 26 is exposed to the accommodating portion side.

  Further, as described above, the paper cassette 43 that stores the paper is provided below the base portion 200. The paper cassette 43 is also provided on the opening 74 side (that is, on the front side), like the base portion 200. It is attached to the apparatus main body 1a so that it can be pulled out.

  In such a laser printer 1, the base 201 of the base portion 200 (the portion to be held with the transfer roller 26 and the registration roller 9) has a transfer roller receiving portion 255 for receiving the transfer roller 26, as shown in FIG. A sheet guide unit 210 that is disposed upstream of the transfer roller receiving unit 255 and guides the sheet 3 toward the photosensitive drum 21 is provided continuously and integrally. In addition to the transfer roller 26, a pair of registration rollers 9 is rotatably provided in the base unit 200, and the paper guide unit 210 is configured to transfer paper between the pair of registration rollers 9 and the transfer roller 26. It is provided so as to be supported and guided to the transfer roller 26.

  The transfer roller receiving portion 255 is formed in a concave shape in cross section along a width direction (hereinafter simply referred to as a width direction) orthogonal to the paper transport direction, and the transfer roller 26 is a transfer roller receiving portion having the concave shape. The transfer roller receiving portion 255 rotatably supports the transfer roller receiving portion 255 in a state of being opposed to and in contact with the photosensitive drum 21 below the photosensitive drum 21.

  The paper guide part 210 forms a part of the base part 201, and the rear end part (the end part on the upstream side in the paper transport direction, the same applies hereinafter) to the front end part (the end part on the downstream side in the paper transport direction, the same applies hereinafter) .) Is formed in a substantially flat plate shape that is slightly inclined upward, and includes a holding portion 257 and an introduction portion 259 provided with a rib member 258 continuously and integrally. The holding portion 257 is fixed to the transfer roller receiving portion 255, and its front end portion is continuous with the rear end portion of the transfer roller receiving portion 255 and its rear end portion is continuous with the front end portion of the introducing portion 259. A step 261 is formed for holding a film member 213 which is formed and will be described later.

  The step 261 is formed as a step having a substantially L-shaped cross section that is recessed downward, and the height H of the step is such that the step 261 has a rear end of the film member 213 as shown in FIG. The upper surface of the film member 213 (described later) when the portion 264 is supported is set to be equal to or lower than the height H of the step.

  As shown in FIG. 5, the introduction portion 259 is formed such that its front end portion is continuous with the rear end portion of the holding portion 257 and its rear end portion extends in the vicinity of the side of the registration roller 9. The introduction portion 259 is provided with a rib member 258. The rib member 258 is formed for the purpose of reinforcing the base 201 and reducing the frictional resistance during paper conveyance. The rib member 258 is plate-shaped and is erected on the introduction portion 259 along the paper conveyance direction. In FIG. 2, a plurality of sheets are formed at predetermined intervals along the width direction of the sheet 3. Further, the front end portion of each rib member 258 is provided at a height substantially equal to the height of the rear end portion of the step portion 261, that is, the higher surface of the high surface and the low surface forming the step. Yes.

  As shown in FIGS. 5 and 6, a flexible film member 213 that supports the paper by cantilevering from the end on the transfer roller 26 side of the paper guide portion 210 to the transfer roller 26 side. The film member 213 corresponds to a paper support member in the claims). The film member 213 is configured to guide the sheet toward the photosensitive drum 21, is configured so that a leading end portion close to the photosensitive drum 21 is bent, and a rear end portion opposite to the leading end portion is fixed in position. . In the illustrated example, a film member 213 as a flexible member, which is a paper support member, is supported on the step portion 261 of the holding portion 257. On the other hand, as shown in FIG. 5, the transfer roller 26 is held by the base part 200 so that the whole is positioned below the upper end part 213 a of the film member 213.

  The film member 213 is made of an insulating material, for example, a resin such as polyethylene terephthalate, and is formed as a substantially rectangular film having a thickness of 80 to 200 μm by pressing. This film member 213 has a Young's modulus E in a direction parallel to the conveyance direction of the paper 3 and a cross-sectional secondary moment in a direction parallel to the axial direction of the photosensitive drum 21 and perpendicular to the widest surface of the film member 213. The product EI with I is formed to be in the range of 3.49 × 10 −5 ≦ EI ≦ 1.18 × 10 −3, for example.

  The film member 213 has a rear end portion 264 attached to the upper surface of the step portion 261 with a double-sided tape 262 so that the front end portion 263 bends in the vicinity of the photosensitive drum 21. Therefore, it is necessary to set the height of the step portion 261 in consideration of not only the thickness of the film member 213 but also the thickness of the double-sided tape 262. When the film member 213 is attached in this manner, the film member 213 has its surface, that is, a press, when the surface on the side in contact with the cutting blade is the front surface and the surface on the opposite side is the back surface. The processing surface is disposed so that the upper surface is in contact with the sheet 3, and the rear surface is disposed so as to be the lower surface opposite to the upper surface of the stepped portion 261.

  Further, the leading end portion 263 of the film member 213 that can be bent and deformed (that is, the portion not facing the upper surface of the step portion 261 in the film member 213) has a length l (see FIG. 6) set to 1 mm or more, Further, the edge thereof does not come into contact with the photosensitive drum 21 and connects a contact portion (transfer position) between the photosensitive drum 21 and the transfer roller 26 and a contact portion between the two registration rollers 9 arranged to face each other. It is arranged on the upper side with respect to the line segment L.

Further, as shown in FIG. 7A, the film member 213 is orthogonal to the conveyance direction of the paper (here, the paper is illustrated by the broken line 3) in the film member 213 and is substantially parallel to the axial direction of the photosensitive drum 21. The width Wg in this direction, that is, the width Wg in the width direction is provided so as to satisfy the following relationship with respect to the maximum width Wp of the paper 3 on which an image can be formed by the laser printer 1.
Wg ≧ Wp−0.04 (m)
In addition, in this base part 200, it is suitable to satisfy | fill said relationship, However, The film member 213 may be continuously formed in the width direction of the paper 3, as shown to Fig.7 (a). Moreover, as shown in FIG.7 (b), you may divide and form. That is, in FIG.7 (b), the some film member 213 is provided in parallel at predetermined intervals in the width direction, and the total width Wg of the width Wgi of each film member 213 satisfy | fills said relationship. Is preferred.

  In this way, in the film member 213 supported by the step portion 261, the contact position of the front end of the sheet 3 with respect to the photosensitive drum 21 can be set using the bending of the front end portion 263 of the film member 213. The photosensitive drum 21 is provided at a position where it can be guided such that the contact angle θ between the photosensitive drum 21 and the paper 3 is θ <90 °.

  According to such a configuration, the rear end portion of the film member 213 is fixed in position, and the front end portion is configured to bend. Therefore, when guiding thin paper, the thin paper is weak. Even when the leading edge of the thin paper comes into contact with the image carrier, the film member 213 can guide the thin paper as it is to the transfer position without being bent so much as it is. Therefore, it is possible to prevent the occurrence of discharge patterns due to the discharge of thin paper. In the case of guiding a thick sheet, when the leading end of the thick sheet comes into contact with the image carrier, the film member 213 corresponds to the direction of the leading end of the thick sheet because the thick sheet is strong. The leading end of the thick paper can be guided to the transfer position so as not to be bent. Therefore, it is possible to prevent a ghost from being generated due to the leading edge of a thick sheet being folded.

  In addition, the arrangement in which the film member 213 is arranged as described above has the above advantages and is effective, but the entire transfer roller 26 is positioned below the film member 213 as in the present embodiment. In the configuration in which the film member 213 is simply accessed by inserting the hand from the side, the film member 213 is disposed in a manner that interferes with the access path on the front side of the transfer roller 26, and thus becomes an obstacle. It becomes difficult to access. In order to deal with such a problem, in the present embodiment, the base unit 200 can be slid and the transfer roller 26 can be easily accessed. Therefore, an easy-to-operate configuration can be realized while taking advantage of the film member.

  In the above configuration, the upper end 213b of the film member 213 is inclined at the end on the transfer roller 26 side of the paper guide portion 210 so as to become higher toward the transfer roller 26, and the upper surface 213b is claimed in the claims. This corresponds to the sheet support inclined surface. Such a paper support inclined surface may be realized without providing the film member 213. In any case, the transfer roller 26 can be held by the base portion 200 so that the entire transfer roller 26 is located below the upper end portion of the sheet support inclined surface.

(D) Configuration of Fixing Unit As shown in FIG. 1, the fixing unit 13 is disposed on the downstream side of the process unit 12, and includes a heating roller 32, a pressing roller 31 pressed against the heating roller 32, and these heating units. A pair of conveying rollers 33 provided on the downstream side of the roller 32 and the pressing roller 31 is provided. The heating roller 32 is made of metal and includes a halogen lamp for heating. The toner transferred on the paper in the process unit 12 is heated while the paper passes between the heating roller 32 and the pressing roller 31. After fixing, the paper is conveyed to the paper discharge path 56 by the conveyance roller 33. The sheet sent to the paper discharge path 56 is sent to a paper discharge roller 34 described later, and is discharged onto the paper discharge tray 35 by the paper discharge roller 34. In the present embodiment, the transport roller 33, the paper discharge path 56, and the paper discharge roller 34 correspond to a second direction changing portion referred to in the claims, and the sheet that has passed through the transfer roller 26 by these is the front side. The direction is changed so as to be directed to the paper discharge tray 35 (the paper discharge tray 35 corresponds to a paper discharge portion in the claims) side.

  In the laser printer 1, the toner remaining on the photosensitive drum 21 after being transferred onto the sheet by the transfer roller 26 is collected by the developing roller 22, and the remaining toner is collected by a so-called cleanerless system. If the toner remaining on the photosensitive drum 21 is collected by such a cleaner-less method, there is no need to provide a cleaning device such as a blade or a waste toner storage unit, so that the configuration of the device is simplified, the size is reduced, and the cost is reduced. Can be achieved.

(3) Configuration of Double-sided Image Forming Unit The laser printer 1 is provided with a reversal conveyance unit 52 as a double-sided image forming unit in order to form images on both sides of the paper. The reverse conveyance unit 52 includes a paper discharge roller 34, a reverse conveyance path 53, a flapper 54, and a reverse conveyance roller 55.

  The paper discharge roller 34 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 34 rotates in the forward direction when the paper is discharged onto the paper discharge tray 35, but rotates in the reverse direction when the paper is reversed. The reverse conveyance path 53 is provided along the vertical direction so that the paper can be conveyed from the paper discharge roller 34 to the reverse conveyance roller 55 disposed below the image forming unit 5. The end portion is disposed near the paper discharge roller 34, and the downstream end portion thereof is disposed near the reverse conveyance roller 55.

  The flapper 54 is swingably provided so as to face a branch portion between the paper discharge path 56 and the reverse conveyance path 53, and the paper is reversed by the paper discharge roller 34 by excitation or non-excitation of a solenoid (not shown). Is configured to be able to be switched from the direction toward the paper discharge path 56 to the direction toward the reverse conveyance path 53. The reverse conveyance roller 55 is located above the sheet feeding cassette 43, and its upstream end is disposed near the rear end of the reverse conveyance path 53, and its downstream end is the end of the registration roller 9. It is provided in a substantially horizontal direction so as to be disposed below.

  When forming images on both sides of the paper, the reversing conveyance unit 52 is operated as follows. That is, when a sheet with an image formed on one side is sent from the sheet discharge path 56 to the sheet discharge roller 34 by the transport roller 33, the sheet discharge roller 34 rotates forward with the sheet sandwiched therebetween. When the paper is once transported outward (discharge tray 35 side), most of the paper is sent to the outside, and the rear end of the paper is sandwiched between paper discharge rollers 34, the forward rotation is stopped. Next, the paper discharge roller 34 rotates in the reverse direction, and the flapper 54 switches the conveyance direction so that the paper is conveyed to the reverse conveyance path 53, and conveys the paper to the reverse conveyance path 53 in the reverse direction. To do. The flapper 54 is switched to the original state, that is, the state in which the paper fed from the transport roller 33 is sent to the paper discharge roller 34 when the transport of the paper is completed. Next, the sheet conveyed in the reverse direction to the reverse conveyance path 53 is conveyed to the reverse conveyance roller 55, reversed from the reverse conveyance roller 55 in the upward direction, and sent to the registration roller 9. The sheet conveyed to the registration roller 9 is turned upside down and again sent to the image forming unit 5 after a predetermined registration, whereby a predetermined image is formed on both sides of the sheet.

<Embodiment 2>
Next, Embodiment 2 will be described with reference to FIGS. 10 and 11.
The base part 200 of the present embodiment includes mounting means for detachably mounting the process unit 12, and as shown in FIG. 10, the point that the process unit 12 and the base part 200 slide integrally is the same as in the first embodiment. Since other points are substantially the same as those of the first embodiment, the same parts are denoted by the same reference numerals, and detailed description thereof is omitted. Specifically, a pair of unit holding portions 205 are provided at both ends in the width direction of the base portion 200, and the unit holding portions 205 correspond to the mounting means described above. The unit holding unit 205 is configured with the upper side opened, and configured to hold the shaft portion 21a of the photosensitive drum 21.

  When the shaft portion 21a of the photosensitive drum 21 is held as shown in FIG. 11, the process unit 12 has an opening formed in the front-rear direction (in this embodiment, in the direction orthogonal to the axial direction) with respect to the base portion 200. The relative movement of the front and rear direction is restricted with the front side as the front and the opposite side as the rear. In this state, by pulling out the base part 200 toward the opening 74, both are pulled out as shown in FIG. 10 with the process unit 12 mounted on the base part 200. The base unit 200 may be configured to slide until the whole comes out of the apparatus main body unit 1a, or may be configured to stop at a certain position. In the present embodiment, the base portion 200 is slid until at least the process unit 12 can be detached upward. In addition, the slide mechanism in this embodiment can also be comprised similarly to Embodiment 1. FIG. Also in the example of FIG. 11, a stopper 78 is provided as positioning means for positioning the base portion 200 and the apparatus main body portion 1 a as in the first embodiment.

  Note that the mounting configuration shown in FIG. 11 is merely an example, and other configurations may be used as long as the process unit 12 can be attached to and detached from the base unit 200. Further, FIG. 11 illustrates a configuration in which the base unit 200 and the process unit 12 are engaged at one place on the rear side of the process unit 12, but a plurality of engagement places may be provided.

<Embodiment 3>
Next, Embodiment 3 will be described with reference to FIGS.
The present embodiment is an example in which the present invention is applied to a so-called tandem type laser printer including a plurality of image forming units corresponding to a plurality of colors. FIG. 12 conceptually shows the internal configuration of the laser printer 90 according to the third embodiment, and FIG. 13 illustrates a state where the base unit 300 including the transfer roller 112 is slid from the laser printer 90.

  Specifically, as shown in FIG. 12, in the laser printer 90, for example, image forming units 91 corresponding to four colors of yellow, magenta, cyan, and black are arranged in a line, and a tandem belt mechanism is provided below the image forming units 91. 92 is arranged. The paper 96 transported by the paper feed roller 94 and the transport roller 95 from the paper storage portion 93 provided on the lower side of the tandem belt mechanism 92 is provided in the transport path between the transport roller 95 and the tandem belt mechanism 92. Then, it is placed on the transport belt 92a of the tandem belt mechanism 92 through the guide portion 97. The paper 96 placed on the transport belt 92a is sequentially transported to the image forming position of each image forming unit 91 by the tandem belt mechanism 92.

Each image forming unit 91 has the same configuration except for the color of the toner accommodated therein. Each image forming unit 91 includes a process unit 98 and a scanner unit 99. Among these, the process unit 98 includes a photosensitive drum 100, a cleaner (not shown) arranged so as to surround the peripheral surface of the photosensitive drum 100, a charger 101, and a developing device 102.
The developing device 102 also serves as the toner container 103 and forms a housing on the front end side of the process unit 98. The photosensitive drum 100, the cleaner, and the charger 101 are held by a frame of the casing on the rear end side of the process unit 98.
The developing device 102 contains toner of each color inside, and a developing roller 104 is rotatably held in a lower opening. A supply roller 105 is pressed against the developing roller 104, and the toner is supplied to the peripheral surface of the developing roller 104 so that the toner is rubbed by the supply roller 105.

  The scanner unit 99 includes a laser light emitting unit (not shown), a polygon mirror that is rotationally driven, lenses 107 and 108, reflecting mirrors 109, 110, and 111, and the like, and each color image data emitted from the laser light emitting unit. As shown by a chain line in FIG. 12, the photosensitive drum 100 of the process unit 98 is passed through or reflected in the order of the polygon mirror, the lens 107, the reflecting mirrors 109 and 110, the lens 108, and the reflecting mirror 111. An electrostatic latent image is formed on the surface of the substrate by high-speed scanning.

  The electrostatic latent image formed on the surface of the photosensitive drum 100 of each process unit 98 is developed with toner of each color by the developing device 102 and transferred onto the paper 96 by the transfer roller 112. As a result, on the paper 96 conveyed on the conveyance belt 92 a of the tandem belt mechanism 92, the respective color images are sequentially transferred by the image forming units 91 to form a color image. In FIG. 12, reference numeral 114 denotes a fixing device including a heating roller and a pressing roller, and reference numeral 115 denotes a paper discharge roller corresponding to the paper discharge roller 34 of the first embodiment.

  Also in this embodiment, the base portion 300 including the transfer roller 112 is configured to be slidable in a direction substantially orthogonal to the axial direction of the transfer roller 112. 12 includes a transfer roller 112, a tandem belt mechanism 92, a guide portion 97 (corresponding to a paper guide portion in the claims), and a conveyance roller 95, and is unitized. As shown in FIG. 1, these are configured to be slidable integrally. The slide configuration of the base unit 300 can be performed by the guide groove 90b formed in the apparatus main body unit 90a and the guided unit 300b formed in the base unit 300, as in the first embodiment.

  The base unit 300 may be configured to slide independently so that each image forming unit 91 and the transfer roller 112 are separated from each other. As shown in FIG. The unit 91 may be configured to slide integrally with the unit 91 mounted. In the example of FIG. 13, similarly to the holding configuration of the second embodiment, each unit holding unit 305 provided corresponding to each image forming unit 91 in the base unit 300 includes the photosensitive drum 100 of each image forming unit 91. The shaft portions 100a are respectively held, and are integrally slid in a state where they are engaged. Although the fixing configuration is not illustrated, in the present embodiment, the scanner unit 99 is also held in a fixed state by the base unit 300. Each unit holding part 305 is provided as a pair so as to support both ends of the shaft part 100a of the photosensitive drum 100. Note that the image forming unit 91 may be supported by a part other than the unit holding unit 305. Here, an example in which the image forming unit 91 is mounted on the base unit 300 is shown, but the configuration for mounting each image forming unit 91 on the base unit 300 may be other than this.

1 is a side sectional view of a main part of a laser printer according to Embodiment 1 of the present invention. Side cross-sectional view showing enlarged process cartridge The principal part sectional side view which expands and shows the state which slid the base part The principal part top view which expands and principally shows the principal part of a base part FIG. 1 is an enlarged view of the main part showing the main part configuration of FIG. FIG. 5 is an enlarged view of a part of FIG. Explanatory drawing explaining a film member Explanatory drawing explaining notionally about attachment / detachment operation of a base part The conceptual diagram which illustrates notionally the state from which a process cartridge and a base part are accommodated in an accommodating part from the front The principal part sectional side view which expands and shows the state which made the base part slide in the laser printer which concerns on Embodiment 2. FIG. Explanatory drawing explaining the structure of the laser printer of Embodiment 2 notionally. Sectional side sectional view of the laser printer of the laser printer of Embodiment 3 Explanatory drawing explaining the structure of the laser printer of Embodiment 3 notionally.

Explanation of symbols

1. Laser printer (image forming device)
DESCRIPTION OF SYMBOLS 1a ... Main part of apparatus 9 ... Registration roller 12 ... Process unit (process cartridge)
21 ... Photosensitive drum (image carrier)
26: Transfer roller 26a ... Roller part 26b ... Shaft member 35 ... Paper discharge tray (paper discharge part)
43: Paper feeding cassette 70: Housing part 74 ... Opening 77 ... Guide groove (sliding mechanism)
78. Stopper (positioning means)
82 ... Gear member 200 ... Base part 203 ... Guide part (sliding mechanism)
210: Paper guide portion 213: Film member (paper support member)
213 ... Upper surface of the film member (paper support inclined surface)

Claims (13)

A process cartridge having an image carrier;
An apparatus main body having an accommodating portion for accommodating the process cartridge and having an opening communicating with the accommodating portion on one end side;
A transfer roller having a roller portion arranged to face the image carrier and a shaft member for holding the roller portion;
An image forming apparatus comprising:
While holding the transfer roller rotatably, a base part mounted on the apparatus main body part,
A slide mechanism that slides the base portion in a direction substantially orthogonal to the axial direction of the shaft member with respect to the apparatus main body portion, and pulls the base portion toward the opening portion;
With
The image forming apparatus according to claim 1, wherein the base portion includes a mounting unit that detachably mounts the process cartridge, and is configured to be slidable by the slide mechanism in a state where the process cartridge is mounted. Below the base portion, a paper cassette for storing paper is provided,
The image forming apparatus according to claim 1 , wherein the sheet cassette is attached to the apparatus main body so that the sheet cassette can be pulled out toward the opening. In the base unit, the image forming apparatus according to claim 1 or claim 2, characterized in that the paper guide portion for guiding to the transfer roller supporting the sheet are provided. At the end of the paper guide portion on the transfer roller side, a paper support inclined surface that is inclined so as to become higher toward the transfer roller side is formed,
The image forming apparatus according to claim 3 , wherein the transfer roller is held by the base portion so that the entire transfer roller is positioned below the upper end portion of the sheet support inclined surface. A flexible paper support member is provided which extends in a cantilevered manner from the end on the transfer roller side of the paper guide portion to the transfer roller side, and supports the paper.
5. The image forming apparatus according to claim 3 , wherein the transfer roller is held by the base portion so that the entirety of the transfer roller is positioned below an upper end portion of the paper support member. The image forming apparatus according to any one of claims 1 to claim 5, characterized in that it comprises a positioning means for positioning said device body portion and the base portion. The image according to any one of claims 1 to 6 , wherein the base portion is configured to be slidable by the slide mechanism until the transfer roller is positioned outside the apparatus main body portion. Forming equipment. The base unit, the image forming apparatus according to any one of claims 1 to claim 7, characterized in that it is configured to be removable from the apparatus body. The image according to any one of claims 1 to 8 , wherein the shaft member of the transfer roller is provided with a gear member for transmitting power to the transfer roller from the outside. Forming equipment. A sheet is sandwiched between the transfer roller and the image carrier, and the sheet is moved by rotation of the image carrier.
The transfer roller, the frictional force generated between the paper, the image forming apparatus according to any one of claims 1 to claim 8, characterized in that rotates in conjunction with movement of the paper. The image forming apparatus according to any one of the base unit, according to claim 1 to claim 10 registration rollers, characterized in that it is rotatable. The image forming apparatus changes the direction of a sheet supplied from one end side in the longitudinal direction of the sheet feeding cassette toward the other end side, and sends the sheet to the transfer roller side disposed above the sheet feeding cassette. A direction change part,
A second direction changing portion that changes the direction of the paper that has passed through the transfer roller toward the one end side and sends the paper to the paper discharge portion side disposed above the transfer roller;
Claims 1, characterized in that with a to the image forming apparatus according to claim 11. The image forming according to any one of the transfer roller, according to claim 1 to claim 12, characterized in that it is constituted of the process cartridge so as to be exposed at the housing part side in a state removed from the apparatus main body apparatus.

Images