JP2007226269A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain height of an image forming apparatus to be low without largely changing the arrangement of a paper housing part, a paper supply roller, a processing unit and a scanner unit in the image forming apparatus which forms an image by developing an electrostatic latent image formed on a photoreceptor. <P>SOLUTION: In a printer 1, a resist roller 12 and a fixing unit 18 are arranged at positions where they are superposed in a horizontal direction, and a paper ejection tray 46 has a recessed part, whose base on a side near to a discharge port 24 is at a position lower than the uppermost surface of the fixing unit 18. Therefore, the height of the printer 1 is made low. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that forms an image by developing an electrostatic latent image formed on a photoreceptor.

  2. Description of the Related Art Conventionally, in an image forming apparatus that forms an image by developing an electrostatic latent image formed on a photoconductor with toner, paper is stored using a paper feed roller from a paper storage unit disposed below the apparatus. The paper stored in the section is supplied to the paper transport path one by one, an image is formed on this paper transport path, and the paper after image formation is discharged to a paper discharge tray located above the image forming apparatus Is known (see, for example, Patent Document 1).

  In this image forming apparatus, a process unit including a photoconductor and a toner tank, a scanner unit including a polygon mirror for forming an electrostatic latent image on the photoconductor by scanning a laser beam, and a sheet are transferred to a sheet. And a fixing unit for fixing the visible image.

  In the vicinity of the paper feed roller, the paper storage unit, the paper feed roller, the process unit, and the scanner unit are arranged in a state of being sequentially stacked in the height direction of the image forming apparatus.

Further, in the vicinity of the fixing unit, the paper storage unit, the fixing unit, and the paper discharge tray are arranged in a state of being sequentially stacked in the height direction of the image forming apparatus.
Further, in this image forming apparatus, the process unit is configured to be removable by passing between the paper feed roller and the scanner unit and moving in the horizontal direction. For example, the process unit is configured to remove the toner in the toner tank. When the remaining amount is low, the toner can be replenished by replacing the process unit.
JP 2003-271030 A

  However, in the vicinity of the paper feed roller of the image forming apparatus, the sheet storage unit, the paper feed roller, the process unit, and the scanner unit are arranged in a stacked state. The height of the sum of the lengths is required. For this reason, the height of the image forming apparatus is increased, and there is a problem that it cannot be reduced in size.

In the vicinity of the fixing roller, the paper storage unit, the fixing unit, and the paper discharge tray are arranged in a stacked state, and thus the same problem occurs.
In addition, if the arrangement of the above-described parts is greatly changed in order to reduce the height of the image forming apparatus, it may be necessary to arrange extra parts or it may be difficult to remove the process unit.

  Therefore, in view of such problems, in an image forming apparatus that forms an image by developing an electrostatic latent image formed on a photoconductor, a paper storage unit, a paper feed roller, a process unit, and a scanner unit An object of the present invention is to keep the height of the image forming apparatus low without significantly changing the arrangement.

  The invention made to achieve such an object is to scan a laser beam with a polygon mirror, and to irradiate the photoconductor with the scanned laser beam, thereby forming an electrostatic latent image on the photoconductor, and An image forming apparatus that generates a visible image by developing an electrostatic latent image formed on a body with a developer, and transfers the visible image generated on the photosensitive member to a recording medium at an image forming position. A recording medium storage unit that stores the recording medium in a stacked state below the image forming apparatus, and is positioned above the recording medium storage unit and stored in the recording medium storage unit. The recording medium is positioned above a conveyance path for conveying the recorded medium to the outside of the image forming apparatus via the image forming position, and near the end of the recording medium storage unit. Recorded at the top of the section A supply roller for supplying a medium to the transport path, and a development for storing at least the developer supplied to the photosensitive member, disposed above the recording medium storage unit and in a position close to the supply roller. A process unit that has an agent storage portion and passes through the upper portion of the supply roller and can be removed from the image forming apparatus in a substantially horizontal detaching direction; and is disposed above the process unit, and at least the polygon mirror A scanner unit, and the scanner unit has a tapered shape with a small thickness on the supply roller side in the attachment / detachment direction so that the process unit can be taken out, and a part of the transport path is An image located on the transport path is formed in an area between the process unit and the recording medium storage unit. Forming position is characterized in that in a position lower than the upper end of the feed roller.

  In this image forming apparatus, a height corresponding to the sum of the heights of the recording medium storage unit, the supply roller, the process unit, and the scanner unit is required. That is, the thickness of the component located in the region directly above the supply roller has the most influence on the height of the image forming apparatus.

  For this reason, in the present invention, in order to reduce the height of the image forming apparatus, the components located in the region immediately above the supply roller are configured to be as thin as possible. Further, the components are arranged so that the space in the height direction of the image forming apparatus can be used effectively in the region other than directly above the supply roller. In addition, the process unit, which is one of the constituent elements, is configured to be able to be taken out in a substantially horizontal attaching / detaching direction through the upper part of the supply roller.

  That is, the scanner unit in the image forming apparatus of the present invention has a tapered shape with a small thickness on the supply roller side in the attaching / detaching direction so that the process unit can be taken out.

  In addition, a part of the transport path is formed in an area sandwiched between the process unit and the recording medium storage unit, and the image forming position located on the transport path is lower than the upper end of the supply roller. It is set as follows.

  Therefore, according to this image forming apparatus, the process unit can be easily taken out, and the height of the image forming apparatus at the position of the supply roller is reduced compared to the case where the scanner unit is not tapered. can do.

  Further, since the position of the process unit or the like can be lowered by the amount that the image forming position is lower than the upper end of the supply roller, the height of the image forming apparatus at the image forming position can be lowered.

Further, the image forming position located on the transport path may be arranged at a position lower than the upper end of the transport path from the recording medium storage unit to the image forming position.
The process unit preferably includes a photoconductor.

According to such an image forming apparatus, the photosensitive member can be replaced when the process unit is replaced.
Furthermore, it is preferable that the process unit includes a transfer roller that transfers a visible image on the photosensitive member to a recording member.

  According to such an image forming apparatus, the transfer roller can be replaced when the process unit is replaced. In addition, by providing a transfer roller in the process unit, the height of the process unit in the vertical direction is increased. However, the above configuration increases the space for removing and attaching the process unit without increasing the height of the apparatus main body. It can be secured.

In addition, when the scanner unit includes an upper plate and a lower plate constituting the outer wall, it is desirable that the lower plate is arranged to be inclined from the horizontal direction with respect to the upper plate.
According to such an image forming apparatus, the height in the vicinity of the supply roller can be reliably reduced.

  The scanner unit further includes a polygon motor that rotates the polygon mirror, and two reflecting mirrors that sequentially reflect the laser beam scanned by the polygon mirror and guide it to the photosensitive member, and reflects the laser beam first. In the scanner unit, the reflecting mirror is positioned on the supply roller side in the attaching / detaching direction, and the polygon mirror, the polygon motor, and the reflecting mirror that reflects the laser beam later are opposite to the supplying roller in the attaching / detaching direction in the scanner unit. It is desirable to be on the side.

  According to such an image forming apparatus, since the scanner unit can be surely formed into a tapered shape with a small thickness on the supply roller side, the height in the vicinity of the supply roller can be reduced.

Further, it is preferable that the conveyance path is inclined downward in the entire section from the upper end of the supply roller to the image forming position.
With such an image forming apparatus, the upper area in the area from the paper feed roller to the image forming position in the area near the conveyance path can be used effectively, so the image forming apparatus can be further downsized. be able to.

  By the way, the photosensitive member and the developer accommodating portion are relatively thick among the constituent elements and require a large space. Therefore, the photosensitive member and the developer accommodating portion are preferably located in a region located directly above the roller for conveying the recording medium. It is desirable not to arrange. Specifically, the photosensitive member and the developer storage unit may be arranged in a region closer to the image forming position in the attaching / detaching direction than the region directly above the supply roller. In addition, when a registration roller disposed on the conveyance path from the supply roller to the image forming position is provided, the photosensitive member and the developer storage section form an image in the detaching direction rather than the area directly above the registration roller. It may be configured to be arranged in the region on the position side.

  According to such an image forming apparatus, the photosensitive member and the developer accommodating portion are arranged without being stacked with the supply roller or the registration roller, so that the size of the photosensitive member and the position developer accommodating portion is ensured. The image forming apparatus can be reduced in size.

  The scanner unit has a taper shape with a small thickness on the supply roller side. Since the taper portion also has a constant thickness, the scanner unit has an image forming apparatus in the attachment / detachment direction rather than the region directly above the supply roller. It is desirable to arrange in the side area.

According to such an image forming apparatus, since the scanner unit is disposed without being stacked with the supply roller, the height of the image forming apparatus at the position where the supply roller is disposed can be reduced.

  Furthermore, a fixing roller that fixes the developer transferred to the recording medium to the recording medium, and a discharge roller that is disposed in the vicinity of the discharge port that discharges the fixing roller and the recording medium to the outside of the image forming apparatus are provided on the conveyance path. And a guide for guiding the recording medium in a section from the fixing roller to the discharge roller, and a section from the fixing roller to the discharge roller is a conveyance direction of the smallest recordable recording medium It is desirable to be shorter than the length at.

  In such an image forming apparatus, since it is not necessary to provide other rollers between the fixing roller and the discharge roller in the conveyance path, a space for arranging the other rollers can be saved. As a result, the image forming apparatus can be reduced in size.

  In order to reduce the size of the image forming apparatus, the recording medium that has passed through the fixing roller may be immediately bent and discharged from the discharge port. However, if the recording medium that has passed through the fixing roller is immediately bent, There is a risk that the recording medium discharged from the discharge port will remain curved. For this reason, it is preferable that the guide constituting the conveyance path is set so that the curvature in the vicinity of the discharge roller in the guide is larger than the curvature in the vicinity of the fixing roller.

According to such an image forming apparatus, the position where the discharge roller is disposed can be set as low as possible while effectively curling the recording medium.
Furthermore, the conveyance path has a shape that reverses the recording medium downstream of the image forming position in the conveyance direction of the recording medium and in the vicinity of the supply roller, and the conveyance path is viewed from the axial direction of the supply roller. In this case, it is desirable to form in an S shape.

  According to such an image forming apparatus, it is possible to form a transport path that is long for the size of the image forming apparatus, and thus it is possible to efficiently arrange the components to be disposed in the vicinity of the transport path.

  In the image forming apparatus, a fixing unit including a fixing roller for fixing the developer transferred to the recording medium to the recording medium, and a recording medium on which the developer is fixed by the fixing unit are arranged above the image forming apparatus. A recording medium stacking unit that stacks the recording medium that has passed through the conveyance path and is discharged from the discharging port at the upper part of the image forming apparatus. It is preferable that the recording medium stacking section includes a recess such that the bottom surface on the side close to the discharge port is positioned lower than the uppermost surface of the fixing unit.

  According to such an image forming apparatus, since the concave portion of the recording medium stacking portion is formed at a position lower than the uppermost surface of the fixing unit, the position of the discharge port can be set without reducing the loading amount of the recording medium. Can be lowered. For this reason, the height of the image forming apparatus in the vicinity of the discharge port can be reduced.

  In addition, a heating unit that generates heat upon energization in the fixing unit, a blocking unit that is disposed above the fixing roller and blocks the energization of the heating unit at a predetermined temperature, and a supply roller that is located immediately below the fixing roller. And a pressing roller that is pressed in the direction of the rotation center of the fixing roller, and the blocking means has the rotation centers of the fixing roller and the pressure roller. It is preferable to lie on a plane orthogonal to the connecting virtual straight line.

  In other words, since the blocking means detects heat generated from the fixing roller, it is desirable that the blocking means is disposed above the fixing roller. However, the blocking means is located above the fixing roller or directly above the fixing roller. In order to secure a space for disposing the blocking means, it is also arranged in the transport direction of the recording medium (that is, a position shifted to the opposite side of the direction of the supply roller from the position directly below the fixing roller). Since the position of the concave portion of the recording medium lamination portion becomes a high position, the blocking means of the present invention is configured to be positioned on a plane orthogonal to a virtual straight line connecting the rotation centers of the fixing roller and the pressure roller. It is.

Therefore, according to such an image forming apparatus, since the position of the concave portion in the recording medium stacking portion can be lowered, the height of the image forming apparatus can be further reduced.
Further, when the image forming apparatus includes a cover that covers the fixing roller and the blocking unit in a state where the pressure roller is exposed, the cover is an imaginary straight line that connects the rotation centers of the fixing roller and the pressure roller. It is preferable to support the blocking means on a plane perpendicular to.

  According to such an image forming apparatus, it is possible to employ a configuration in which a cover is not provided below the fixing unit. Therefore, the height of the image forming apparatus can be reduced by the thickness of the cover.

  Further, when the image forming apparatus includes a substrate on which an electronic circuit for electrically controlling each part of the image forming apparatus is mounted, the substrate is provided on one side of the image forming apparatus. It is desirable that they are arranged along a vertical plane parallel to the desorption direction.

  In such an image forming apparatus, since the thickness of the substrate can be prevented from being reflected in the height of the image forming apparatus, the height of the image forming apparatus can be reduced as compared with the case where the substrate is laid down. Can do.

  Furthermore, the photosensitive member has a cylindrical shape extending in a direction orthogonal to the conveyance direction of the recording medium, and after the surface of the photosensitive member is charged by a charger, the surface is irradiated with laser light, thereby electrostatic latent images. In the image forming apparatus, a charger for charging the photosensitive drum is provided at a position within 45 degrees from the horizontal in the radial direction of the photosensitive drum. It is desirable to arrange for charging.

  According to such an image forming apparatus, the charger can be prevented from protruding upward from the upper end of the photosensitive drum, so that the height of the charger can be hardly reflected in the height of the image forming apparatus.

  Further, the recording medium stacked in the recording medium storage unit is disposed in the vicinity of a position where the recording medium can be conveyed by the supply roller, a feeding roller that conveys the recording medium to a position where the recording medium can be conveyed by the supply roller, A separation pad that engages with the supplied recording medium when only a plurality of recording media are supplied by the delivery roller, and allows only the recording medium positioned at the top of the recording medium storage unit to pass through; It is desirable to have.

  According to such an image forming apparatus, since the load applied to the recording pad by the recording medium can be reduced by providing the feeding roller, it is possible to prevent the separation pad and the recording medium from being worn.

  Next, in the invention made to achieve the above object, a laser beam is scanned by a polygon mirror, and an electrostatic latent image is formed on the photosensitive member by irradiating the scanned laser beam to the photosensitive member. The latent electrostatic image formed on the photosensitive member is developed with a developer to generate a visible image, and the visible image generated on the photosensitive member is transferred to a recording medium at an image forming position. An image forming apparatus comprising: a recording medium storage unit that stores the recording medium in a stacked state below the image forming apparatus; and the recording medium storage unit that is positioned above the recording medium storage unit. A recording medium accommodated in the recording medium, a conveyance path for conveying the recording medium to the outside of the image forming apparatus via the image forming position, and fixing the developer transferred to the recording medium to the recording medium. Fixing unit with fixing roller A discharge port for discharging the recording medium on which the developer is fixed by the fixing unit to the upper portion of the image forming apparatus, and the discharge port passing through the conveyance path at the upper portion of the image forming apparatus. A recording medium stacking unit that stacks the recording medium discharged from the recording medium, and the recording medium stacking unit has a bottom surface closer to the discharge port located at a lower position than the uppermost surface of the fixing unit. It is characterized by having a concave portion.

  According to such an image forming apparatus, since the concave portion of the recording medium stacking portion is formed at a position lower than the uppermost surface of the fixing unit, the position of the discharge port can be set without reducing the loading amount of the recording medium. Can be lowered. For this reason, the height of the image forming apparatus in the vicinity of the discharge port can be reduced.

  Furthermore, a fixing roller that fixes the developer transferred to the recording medium to the recording medium, and a discharge roller that is disposed in the vicinity of the discharge port that discharges the fixing roller and the recording medium to the outside of the image forming apparatus are provided on the conveyance path. And a guide for guiding the recording medium in a section from the fixing roller to the discharge roller, and a section from the fixing roller to the discharge roller is a conveyance direction of the smallest recordable recording medium It is desirable to be shorter than the length at.

  In such an image forming apparatus, since it is not necessary to provide other rollers between the fixing roller and the discharge roller in the conveyance path, a space for arranging the other rollers can be saved. As a result, the image forming apparatus can be reduced in size.

  Further, the guide constituting the conveyance path has a predetermined curvature for curving the recording medium after passing through the fixing roller, and the curvature in the vicinity of the discharge roller in the guide is larger than the curvature in the vicinity of the fixing roller. It is preferable that it is comprised.

According to such an image forming apparatus, the position where the discharge roller is disposed can be set as low as possible while effectively curling the recording medium.
In addition, a heating unit that generates heat upon energization in the fixing unit, a blocking unit that is disposed above the fixing roller and blocks the energization of the heating unit at a predetermined temperature, and a supply roller that is located immediately below the fixing roller. And a pressing roller that is pressed in the direction of the rotation center of the fixing roller, and the blocking means has the rotation centers of the fixing roller and the pressure roller. It is preferable to lie on a plane orthogonal to the connecting virtual straight line.

According to such an image forming apparatus, since the position of the concave portion in the recording medium stacking portion can be lowered, the height of the image forming apparatus can be further reduced.
Further, when a cover that covers the fixing roller and the blocking means is provided in a state where the pressure roller is exposed, the cover is on a plane orthogonal to a virtual straight line connecting the rotation centers of the fixing roller and the pressure roller. It is preferable to support the blocking means.

  According to such an image forming apparatus, it is possible to employ a configuration in which a cover is not provided below the fixing unit. Therefore, the height of the image forming apparatus can be reduced by the thickness of the cover.

Embodiments according to the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional side view of a main part of the printer 1. In FIG. 1, the printer 1 is viewed from the axial direction of various rollers, which will be described later. The right side in this figure is referred to as the near side, and the left side is referred to as the back side.

In FIG. 1, a printer 1 forms a predetermined image on a feeder 3 for feeding paper 3 (recording medium in the present invention) or a fed paper 3 in a main body casing 2. The image forming unit 5 is provided.

In addition, an upper portion of the printer 1 is provided with a paper discharge tray 46 (recording medium stacking portion referred to in the present invention) used for holding the paper 3 on which an image has been formed by the printer 1 and discharged.
The feeder unit 4 is provided above a paper feed tray 6 (recording medium storage unit in the present invention), a paper pressing plate 7 provided in the paper feed tray 6, and one end side end of the paper feed tray 6. The sheet feeding roller 11, the sheet feeding roller 8 (supply roller in the present invention) and the separation pad 9, the pinch roller 10 facing the sheet feeding roller 8, the paper dust removing roller 50, and the paper dust removing roller 50. 3 and a registration roller 12 provided on the downstream side in the conveying direction.

  The paper feed tray 6 is detachably attached to the bottom of the main casing 2 and is used for stacking and storing the paper 3 therein. The paper feed tray 6 is pulled out to the front side (right side in FIG. 1) of the printer 1 when the paper 3 is replenished therein. At this time, the feeder unit 4 is separated between the paper feed roller 8 and the separation pad 9, and the pinch roller 10, the separation pad 9, and the spring 13 disposed on the back side of the separation pad 9 are connected to the paper feed tray 6. And pulled out together.

  The paper pressing plate 7 is swingably supported at the end far from the paper feed roller 8 so that the end near the paper feed roller 8 can move in the vertical direction. It is biased upward by a spring (not shown). For this reason, the sheet pressing plate 7 is swung downward against the urging force of the spring with the end farther from the sheet feeding roller 8 as a fulcrum as the amount of stacked sheets 3 increases.

  The feed roller 11 is set so as to abut on the uppermost sheet 3 in the sheet feed tray 6 by the sheet pressing plate 7, and the position where the sheet 3 can be conveyed by the sheet feed roller 8 (the sheet feed roller 8 And a position between the separation pad 9).

  Next, the separation pad 9 is disposed at a position facing the paper feed roller 8. Then, it is pressed toward the paper feed roller 8 by a spring 13 disposed on the back side of the separation pad 9. In addition, the separation pad 9 has a function for preventing the plurality of sheets 3 from being supplied into the transport path in a state where they overlap each other. That is, the sheet 3 sent by the sending roller 11 comes into contact with the sheet feeding roller 8 and the separation pad 9. At this time, since an appropriate frictional force is applied between the separation pad 9 and the paper 3, even if a plurality of papers 3 are sent to the separation pad by the feed roller 11, the paper 3 positioned at the uppermost position. The other sheets 3 are locked by the separation pad 9. For this reason, the paper 3 is supplied from the paper feed roller 8 one by one.

  Then, the paper 3 fed by the paper feed roller 8 is sent to the paper 3 conveyance path (indicated by a two-dot chain line in FIG. 1). At this time, the paper 3 is sent to the registration roller 12 after the paper dust is removed by the paper dust removing roller 50. In addition, this conveyance path is formed downward in the horizontal direction in the entire section from the upper end of the paper feed roller 8 to the image forming position P. A large portion of the transport path from the paper feed roller 8 to the image forming position P is formed by a guide member 51 formed on the main body side of the printer 1 and a bottom surface portion of the process unit 17.

  Here, the paper feed roller 8 changes the direction of the paper 3 by about 180 degrees and sends the paper 3 to the registration roller 12. At this time, if the curvature of the paper 3 being curved by the paper feed roller 8 is large, the paper 3 becomes postcard or the like. If the sheet 3 is thick, the sheet 3 may be bent or the sheet 3 may not be conveyed to the registration roller 12 due to resistance when the sheet 3 is bent.

  Therefore, the diameter of the paper feed roller 8 is set larger than that of the photosensitive drum 27 (photosensitive member in the present invention) and the fixing roller 41 (for example, the diameter of the photosensitive drum 27 is 24 mm, The diameter of the feed roller 8 is 33 mm with respect to the diameter of the fixing roller 41 of 25 mm). Thus, if the diameter of the paper feed roller 8 is set relatively large and the curvature of the paper 3 is reduced, the paper 3 can be transported satisfactorily without being bent by the paper feed roller 8.

  Further, the registration roller 12 is composed of a pair of rollers, and based on the detection timing by the position sensor 64 arranged in the vicinity of the paper feed roller 8, the driving and stopping operations are arranged in a substrate 90 described later. It is controlled by a control device (not shown). The skew of the sheet 3 is corrected by this control. That is, the control device sets the registration roller 12 to be driven when the paper 3 is conveyed by the paper feed roller 8, and stops the registration roller 12 when the position sensor 64 detects the leading edge of the paper 3. Then, when the sheet 3 comes into contact with the registration roller 12 and becomes loose, the control device drives the registration roller again to send the sheet 3 to the image forming unit 5.

The position sensor 64 is a mechanical sensor, and is configured to be displaced from a predetermined position before the sheet 3 comes into contact with the sheet 3 when pressed by the sheet 3.
Further, a manual paper feed port 14 for feeding the paper 3 directly from the front side of the printer 1 to the position of the registration roller 12 is formed slightly above the paper feed roller 8. The paper 3 can be supplied to the transport path without storing the paper 3.

Next, the image forming unit 5 includes a scanner unit 16, a process unit 17, a fixing unit 18, and the like.
The scanner unit 16 is provided in the upper part of the main casing 2 and includes a laser light emitting unit (not shown), a polygon mirror 19 that is rotationally driven by a polygon motor 25, lenses 20 and 21, reflecting mirrors 22 and 23, and the like. The laser beam based on the predetermined image data emitted from the laser light emitting part passes or reflects in the order of the polygon mirror 19, the lens 20, the reflecting mirror 22, the lens 21, and the reflecting mirror 23 as shown by the one-dot chain line in FIG. Thus, the surface of the photosensitive drum 27 in the process unit 17 described later is irradiated by high-speed scanning.

More specifically, in this scanner unit 16, the polygon mirror 19 is disposed immediately above the photosensitive drum 27 and an image forming position P described later, and the laser beam reflected by the polygon mirror 19 is applied to the reflecting mirror 22. It progresses in a substantially horizontal direction. The laser beam is reflected by the reflecting mirror 22 toward the reflecting mirror 23 located immediately below the polygon mirror 19. That is, the reflecting mirror 22 changes the incident laser beam 15 from the horizontal direction.
Reflects at an acute angle downwards about a degree. The scanner unit 16 including these parts (polygon mirror 19, lenses 20 and 21, reflecting mirrors 22 and 23) is set to a size and shape that do not interfere with the optical path of the laser beam. In other words, the upper surface (upper plate) of the scanner unit 16 is arranged in a substantially horizontal direction (strictly, it is inclined so that the side far from the paper feed roller 8 becomes lower). Further, the lower surface (lower plate) of the scanner unit 16 is inclined more greatly than the upper surface so that the one farther from the paper feed roller 8 becomes lower. Therefore, the scanner unit 16 has a tapered shape in which the image forming position P side where the polygon mirror 19 is located is thick and the paper feed roller 8 side is thin.

  The process unit 17 is disposed below the scanner unit 16 and is detachably attached to the main body casing 2 in a substantially horizontal direction and in the front-rear direction (left-right direction: attachment / detachment direction in FIG. 1). The drum cartridge 26 and the developing cartridge 28 are included. A space is formed between the process unit 17 and the scanner unit 16.

In the process unit 17, the drum cartridge 26 includes a photosensitive drum 27, a scorotron charger 29 (charger in the present invention), and a transfer roller 30.
The developing cartridge 28 includes a developing roller 31, a layer thickness regulating blade 32, a toner supply roller 33, a toner box 34, and the like. The developing cartridge 28 is detachably attached to the drum cartridge 26.

  Here, among the constituent elements constituting the process unit 17, the photosensitive drum 27 and the toner box 34 require a relatively large space. For this reason, the photosensitive drum 27 and the toner box 34 are set so as not to be disposed directly above the paper feed roller 8 and the registration roller 12 that require a relatively large space in the vicinity of the process unit 17. Yes.

  The toner box 34 is filled with toner (developer). Then, the toner in the toner box 34 is agitated by the rotation of the agitator 36 supported by the rotation shaft 35 provided at the center of the toner box 34 in the arrow direction (clockwise direction), and is provided in the toner box 34. Released from the toner supply port 37.

  A toner supply roller 33 is rotatably disposed in a side position of the toner supply port 37, and the developing roller 31 rotates counterclockwise so as to face the toner supply roller 33. It is arranged to be possible. The toner supply roller 33 and the developing roller 31 are in contact with each other in a state where each of them is compressed to some extent.

  The toner supply roller 33 has a metal roller shaft covered with a roller made of a conductive foam material. The developing roller 31 has a metal roller shaft covered with a roller made of a conductive rubber material having no magnetic characteristics. More specifically, the roller part of the developing roller 31 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 developing bias is applied to the developing roller 31.

  In addition, a layer thickness regulating blade 32 is disposed in the vicinity of the developing roller 31. The layer thickness regulating blade 32 includes a pressing portion 40 having a semicircular cross section made of insulating silicone rubber at the tip of a blade body made of a metal leaf spring material. 28, the pressing portion 40 is configured to be pressed against the developing roller 31 by the elastic force of the blade body.

  The toner discharged from the toner supply port 37 is supplied to the developing roller 31 by the rotation of the toner supplying roller 33. At this time, the toner is positively frictionally charged between the toner supplying roller 33 and the developing roller 31, The toner supplied onto the developing roller 31 enters between the pressing portion 40 of the layer thickness regulating blade 32 and the developing roller 31 as the developing roller 31 rotates, and is further sufficiently frictionally charged here. , And is carried on the developing roller 31 as a thin layer having a constant thickness.

  The photosensitive drum 27 is disposed at a side position of the developing roller 31 so as to be able to rotate in the clockwise direction so as to face the developing roller 31. The photosensitive drum 27 has a drum main body grounded and a surface portion formed of a positively chargeable photosensitive layer made of polycarbonate or the like. The photosensitive drum 27 is configured to be rotationally driven by power from a main motor (not shown).

  The scorotron charger 29 is disposed at a predetermined interval so as not to contact the photosensitive drum 27. The scorotron charger 29 is disposed approximately 30 degrees above the horizontal direction in the radial direction of the photosensitive drum 27. The scorotron charger 29 is a positively charged scorotron charger that generates corona discharge from a charging wire such as tungsten, and uniformly charges the surface of the photosensitive drum 27 to a positive polarity. It is configured as follows.

  The surface of the photosensitive drum 27 is first uniformly charged positively by the scorotron charger 29 as the photosensitive drum 27 rotates, and then exposed by high-speed scanning of the laser beam from the scanner unit 16. Then, an electrostatic latent image based on predetermined image data is formed.

  Next, the electrostatic charge formed on the surface of the photosensitive drum 27 when the positively charged toner carried on the developing roller 31 comes into contact with the photosensitive drum 27 by the rotation of the developing roller 31. The latent image, that is, the surface of the photosensitive drum 27 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 visualized by being selectively carried. Thereby, reversal development is achieved.

  The transfer roller 30 is disposed below the photosensitive drum 27 so as to face the photosensitive drum 27, and is supported by the drum cartridge 26 so as to be able to rotate counterclockwise. The transfer roller 30 is configured such that a metal roller shaft is covered with a roller made of an ion conductive rubber material, and a transfer bias (transfer forward bias) is applied during transfer. Therefore, the visible image carried on the surface of the photosensitive drum 27 is transferred to the paper 3 while the paper 3 passes between the photosensitive drum 27 and the transfer roller 30 (image forming position P).

  The fixing unit 18 is disposed downstream of the process unit 17 in the sheet conveyance direction (back side), and includes a fixing roller 41 formed with a gear, and a pressure roller 42 that presses the fixing roller 41 (the pressure roller in the present invention). ) And a thermostat 18a (blocking means in the present invention). Also, the fixing roller 41 and the thermostat 18a are covered with a cover 18b.

The fixing roller 41 is made of metal and includes a halogen lamp for heating.
The pressing roller 42 includes a spring 42 a that presses (biases) the pressing roller 42 from below so as to be rotatable in the central axis direction of the fixing roller 41. The pressing roller 42 is in close contact with the fixing roller 41 or the sheet 3 and is configured to rotate in synchronization with the fixing roller 41.

  The thermostat 18a is made of, for example, a bimetal, and turns on / off the power of the heater for heating the fixing roller 41 according to the heat generated from the fixing roller 41 so that the heating roller 42 is not heated to an abnormally high temperature. ing.

  The thermostat 18 a is disposed above the fixing roller 41 and on an extension line (imaginary line) connecting the rotation center of the pressing roller 42 and the fixing roller 41. For this reason, compared to the case where the thermostat 18a is disposed directly above the fixing roller 41 or deeper than the fixing roller 41 (left side in FIG. 1: downstream in the conveyance direction of the paper 3), the paper is discharged. The position of the recess 46a of the tray 46 can be set low.

  The cover 18b prevents heat generated from the fixing roller 41 from being released from the fixing unit 18 to the outside of the fixing unit 18 and adversely affecting other devices (for example, the scanner unit 16) in the main body casing 2. The fixing roller 41 has a shape that covers the side and upper side of the fixing roller 41. Here, the cover 18b only supports the pressing roller 42 so that only the central axis (not shown) is movable and rotatable in the urging direction of the spring 42a. The lower half is exposed from the cover 18b. For this reason, the height of the printer 1 is set lower by the thickness of the cover 18b than when the cover 18b covers the lower side of the pressing roller 42.

  In such a fixing unit 18, the fixing roller 41 heats and presses the toner transferred on the paper 3 in the process unit 17 while the paper 3 passes between the fixing roller 41 and the pressing roller 42. To fix. Further, the fixing roller 41 conveys the sheet 3 after image fixing to the discharge roller 45 through a discharge path formed by guide members 52 and 53 (guides in the present invention). Then, the discharge roller 45 discharges the fed paper 3 onto the paper discharge tray 46. The pair of discharge rollers 45 function as a discharge port 24 for discharging the paper 3 to the outside of the printer 1.

  Here, if the sheet 3 is suddenly bent while being heated by the fixing roller 41, the sheet 3 may not return from the bent state to the original uncurved state. For this reason, the guide members 52 and 53 with which the paper 3 after passing through the fixing roller 41 comes into contact are gently bent after passing through the fixing roller 41 in a heated state, and suddenly bend as the paper approaches the discharge roller 45. It is set to do.

  With this configuration, the position of the discharge port 24 can be made lower than when all the discharge paths of the paper 3 are gently curved, and the printer 3 can be prevented from being permanently bent. It becomes easy to make the height of 1 low.

  The paper discharge tray 46 has a shape that gradually falls from the front side of the printer 1 toward the back side (left side in FIG. 1). The most depressed portion (concave portion 46 a) of the discharge tray 46 is set to a position lower than the upper end of the fixing unit 18. Therefore, the discharge roller 45 can be disposed at a lower position without reducing the number of sheets 3 that can be stacked on the discharge tray 46. For this reason, the height of the printer 1 at the portion where the scanner unit 16 is disposed can be made closer to the height of the printer 1 at the position where the discharge roller 45 is disposed, and the design (appearance) is good. ing.

  In the printer 1, a substrate 90 on which a control device for driving and controlling the various rollers, the polygon mirror 19 and the like is mounted on a substrate 90 as shown by a broken line in FIG. Are arranged on both side surfaces (position where the process unit 17 is sandwiched from the side surface: one side).

  Next, removal of the process unit 17 performed by the user will be described with reference to FIGS. FIG. 2 is an explanatory view showing a state in which the process unit 17 is removed, and FIG. 3 is an explanatory view showing a state in which only the developing cartridge 28 is removed from the process unit 17.

  In removing the process unit 17 in the state shown in FIG. 1, first, the user opens the cover 49 of the printer 1 to the front side of the printer to bring it into the state shown in FIG. At this time, the cover 49 rotates with a support shaft (not shown) as a fulcrum.

  Then, the process unit 17 is pulled out from the state of FIG. 1 in the substantially horizontal direction toward the front side (detachment direction) of the printer 1 and passes over the sheet feed roller 8 and is removed. At this time, since the space is formed between the process unit 17 and the scanner unit 16 as described above, the user is positioned in front of the process unit 17 (side closer to the paper feed roller 8). The process unit 17 can be pulled out as it is by lifting the handle 17a toward the scanner unit 16. With this configuration, the back side (image forming position P side) of the process unit 17 is not easily caught by the main body of the printer 1, and the process unit 17 can be pulled out smoothly.

  Further, when removing the process unit 17, as shown in FIG. 3, only the developing cartridge 28 can be removed while the drum cartridge 26 constituting the process unit 17 is left inside the printer 1. ing.

  In the printer 1 described in detail above, the paper feed tray 6 that stores the sheets 3 in a stacked state below the printer 1, and is positioned above the paper feed tray 6 and stored in the paper feed tray 6. The sheet 3 is positioned above the vicinity of the end of the sheet feeding tray 6 and the conveyance path for conveying the sheet 3 to the outside of the printer 1 via the image forming position P, and is stacked on the top of the sheet feeding tray 6. A paper feed roller 8 for supplying the paper 3 to the transport path, a photoconductor drum 27 and a toner box 34 for storing toner, which are disposed above the paper feed tray 6 and close to the paper feed roller 8. A process unit 17 that passes through the upper part of the paper feed roller 8 and can be taken out from the printer 1 in a substantially horizontal attachment / detachment direction, and is disposed above the process unit 17 and includes at least a polygon mirror 19. Sca It includes a unit 16, a.

  The scanner unit 16 has a taper shape with a small thickness on the side of the paper feed roller 8 in the attaching / detaching direction so that the process unit 17 can be taken out, and a part of the transport path is formed between the process unit 17 and the paper feed tray 6. The image forming position P located on the transport path is lower than the upper end of the paper feed roller 8.

  Accordingly, the process unit 17 can be easily taken out, and the scanner unit 16 is tapered in a region just above the paper feed roller 8, so that the scanner unit 16 is tapered. The height of the printer 1 at the position of the paper feed roller 8 can be reduced as compared with the case where it is not.

  Further, since the position of the process unit 17 or the like can be lowered by the amount that the image forming position P is lower than the upper end of the paper feed roller 8, the height of the printer 1 at the image forming position P can be lowered. .

  Further, since the process unit 17 includes the photosensitive drum 27 and the transfer roller 30, when the process unit 17 is replaced, the photosensitive drum 27 and the transfer roller 30 can also be replaced.

  In addition, the scanner unit 16 includes an upper plate and a lower plate that constitute an outer wall, and the lower plate is disposed so as to be inclined from the horizontal direction with respect to the upper plate. The height can be lowered.

  Further, the scanner unit 16 includes a polygon motor 25 for rotating the polygon mirror 19, two reflecting mirrors 22 and 23 for sequentially reflecting the laser beam scanned by the polygon mirror 19 and guiding it to the photosensitive drum 27, In the scanner unit 16, the reflecting mirror 22 that reflects the laser beam is positioned on the paper feed roller 8 side in the attaching / detaching direction of the process unit 17, and the polygon mirror 19, the polygon motor 25, and the laser beam afterwards. The reflecting mirror 23 that reflects is configured to be located on the opposite side of the scanner unit 16 from the paper feed roller 8 in the attaching / detaching direction of the process unit 17.

Therefore, since the scanner unit 16 can be surely formed into a tapered shape with a small thickness on the paper feed roller 8 side, the height in the vicinity of the paper feed roller 8 can be reduced.
Further, since the conveyance path is inclined downward in the entire section from the upper end of the paper feed roller 8 to the image forming position P, the area from the paper feed roller 8 to the image forming position P in the area near the conveyance path. The upper area in the portion can be used effectively, and the printer 1 can be downsized.

  Further, the photosensitive drum 27 and the toner box 34 constituting the process unit 17 are arranged in a region directly above the paper feed roller 8 and a region on the image forming position P side in the attaching / detaching direction with respect to the registration roller 12. 27 and the toner box 34 are not stacked with the paper feed roller 8 or the registration roller 12, the sizes of the photosensitive drum 27 and the toner box 34 are secured, and the photosensitive drum 27 and the toner box 34 are made small. Therefore, the printer 1 can be downsized.

  In addition, the scanner unit 16 is disposed in the area on the printer 1 side in the attaching / detaching direction with respect to the area directly above the sheet feed roller 8, and the scanner unit 16 is disposed without being stacked with the sheet feed roller 8. Therefore, the height of the printer 1 at the position where the paper feed roller 8 is disposed can be reduced.

  Further, the conveying path is arranged on a conveying path between the fixing roller 41 for fixing the toner transferred to the sheet 3 to the sheet 3 and the discharge roller 24 for discharging the sheet 3 to the outside of the printer 1. A discharge roller 45 disposed in the vicinity of the discharge port 24 and guide members 52 and 53 for guiding the paper 3 in a section from the fixing roller 41 to the discharge roller 45. ing. The section from the fixing roller 41 to the discharge roller 45 is set to be shorter than the length of the smallest recordable sheet 3 in the transport direction.

  Accordingly, since the printer 1 has no other rollers from the fixing roller 41 to the discharge roller 45, a space for arranging the other rollers can be saved, and the printer 1 can be downsized. it can.

  In addition, the guide members 52 and 53 constituting the conveyance path are set so that the curvature of the guide members 52 and 53 near the discharge roller 45 is larger than the curvature of the vicinity of the fixing roller 41, so that the curl of the sheet 3 is effective. Thus, the position where the discharge roller 45 is disposed can be set as low as possible.

Furthermore, the conveyance path has a shape that reverses the sheet 3 in the conveyance direction downstream side of the sheet 3 from the image forming position P and in the vicinity of the sheet feed roller 8, and the conveyance path extends from the axial direction of the sheet feed roller 8. When viewed, it is formed in an S shape.

  Therefore, according to this printer 1, since a conveyance path long for the size of the printer 1 can be formed, components to be arranged in the vicinity of the conveyance path can be efficiently arranged.

  In addition, since the discharge tray 46 has a recess whose bottom surface on the side close to the discharge port 24 is lower than the uppermost surface of the fixing unit 18, the area near the fixing roller 41 can be used effectively. And the position of the discharge port 24 can be lowered. For this reason, the height of the printer 1 in the vicinity of the discharge port 24 can be reduced.

  Further, the pressing roller 42 is disposed in the conveyance direction of the sheet 3 with respect to the fixing roller 41 (that is, a position shifted to the opposite side to the direction of the paper feeding roller 8 from the position directly below the fixing roller 41). The thermostat 18 a is configured to be positioned on a plane orthogonal to a virtual straight line connecting the rotation centers of the fixing roller 41 and the pressing roller 42.

Therefore, according to such a printer 1, since the position of the recessed part 46a in the paper discharge tray 46 can be set to a lower position, the height of the printer 1 can be further reduced.
Further, since the fixing unit 18 can be arranged along the curve formed by the paper discharge tray 46, a useless space in the printer 1 can be reduced.

Further, the cover 18b is configured to cover the fixing roller 41 and the thermostat 18a constituting the fixing unit 18 with the pressing roller 42 exposed.
Therefore, according to such a printer 1, since the cover 18b is not provided below the fixing unit 18, the height of the printer 1 can be reduced by the thickness of the cover 18b.

  Further, the substrate 90 on which electronic circuits for electrically controlling each part of the printer 1 are mounted is directed toward a vertical plane parallel to the attaching / detaching direction of the process unit 17 on one side of the printer 1 (paper feeding). When viewed from the axial direction of the roller 8, the thickness of the substrate 90 can be prevented from being reflected in the height of the printer 1. The height of the printer 1 can be reduced as compared with the case where the printer 90 is laid down.

  In addition, the scorotron charger 29 for charging the photosensitive drum 27 is arranged to charge the photosensitive drum 27 at a position within 45 degrees from the horizontal in the radial direction of the photosensitive drum 27. The scorotron charger 29 can be prevented from protruding upward from the upper end of the photosensitive drum 27, and the height of the scorotron charger 29 can be hardly reflected in the height of the printer 1.

  In addition, in the printer 1, the paper 3 stacked on the paper feed tray 6 is transported to a position where the paper 3 can be transported by the paper feed roller 8, and the paper 3 is transported by the paper feed roller 8. Arranged in the vicinity of a possible position, when a plurality of sheets 3 are supplied by the delivery roller 11, to engage with the supplied sheet 3 and pass only the sheet 3 positioned at the top of the sheet feed tray 6. The separation pad 9 is provided.

  Therefore, according to this printer 1, since the load applied to the separation pad 9 can be reduced by providing the delivery roller 11, the wear of the separation pad 9 and the paper 3 can be prevented.

The embodiment of the present invention is not limited to the above-described embodiment, and can take various forms as long as it belongs to the technical scope of the present invention.
For example, in the printer 1 of the present embodiment, an image is formed on the paper 3. However, this is not particularly necessary, and for example, an OHP sheet or cloth may be used.

  In the present embodiment, the thermostat 18a is used to prevent the fixing roller 41 from being abnormally heated. However, the present invention is not limited to this configuration, and for example, a temperature sensor may be arranged.

FIG. 3 is a side sectional view of a main part of the printer. It is explanatory drawing which shows the state which removed the process unit. It is explanatory drawing which shows the state which removed only the developing cartridge among process units.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Printer, 2 ... Main body casing, 3 ... Paper, 4 ... Feeder part, 5 ... Image forming part, 6 ... Paper feed tray, 7 ... Paper press plate, 8 ... Paper feed roller, 9 ... Separation pad, 10 ... Pinch Roller, 11 ... Sending roller, 12 ... Registration roller, 13 ... Spring, 14 ... Manual feed port, 16 ... Scanner unit, 17 ... Process unit, 17a ... Handle, 18 ... Fixing unit, 18a ... Thermostat, 18b ... Cover 19 ... polygon mirror, 20 ... lens, 21 ... lens, 22 ... reflecting mirror, 23 ... reflecting mirror, 24 ... discharge port, 25 ... polygon motor, 26 ... drum cartridge, 27 ... photosensitive drum, 28 ... developing cartridge, 29 ... Scorotron charger, 30 ... transfer roller, 31 ... developing roller, 32 ... layer thickness regulating blade, 33 ... toner supply roller, 34 ... toner box 35 ... Rotating shaft, 36 ... Agitator, 37 ... Toner supply port, 40 ... Pressing part, 41 ... Fixing roller, 42 ... Pressing roller, 42a ... Spring, 45 ... Ejecting roller, 46 ... Ejecting tray, 46a ... Recessed part, 49 ... cover, 50 ... paper dust removing roller, 51 ... guide member, 52 ... guide member, 53 ... guide member, 64 ... position sensor, 90 ... substrate.

Claims (7)

A laser beam is scanned by a polygon mirror, an electrostatic latent image is formed on the photoconductor by irradiating the scanned laser beam to the photoconductor, and the electrostatic latent image formed on the photoconductor is developed by a developer. An image forming apparatus that generates a visible image by developing and transfers the visible image generated on the photoreceptor to a recording medium at an image forming position,
A recording medium storage unit for storing the recording medium in a stacked state below the image forming apparatus;
A transport path for transporting the recording medium stored in the recording medium storage unit to the outside of the image forming apparatus via the image forming position, located above the recording medium storage unit;
A registration roller that is arranged in the middle of the conveyance path and supplies a recording medium to the image forming position;
A fixing unit comprising a fixing roller for fixing the developer transferred to the recording medium to the recording medium;
A discharge port for discharging the recording medium on which the developer is fixed by the fixing unit to the top of the image forming apparatus;
A recording medium stacking unit that stacks the recording medium discharged from the discharge port through the transport path at the top of the image forming apparatus,
The registration roller and the fixing unit are arranged at positions overlapping in the horizontal direction,
The image forming apparatus according to claim 1, wherein the recording medium stacking portion has a recess such that a bottom surface near the discharge port is positioned lower than an uppermost surface of the fixing unit. The transport path includes
A fixing roller for fixing the developer transferred to the recording medium to the recording medium;
A discharge roller disposed in the vicinity of a discharge port for discharging the recording medium to the outside of the image forming apparatus;
A guide for guiding the recording medium in a section from the fixing roller to the discharge roller,
The image forming apparatus according to claim 1, wherein a section from the fixing roller to the discharge roller is shorter than a length in a conveyance direction of a recording medium having the smallest size that can be recorded. The guide constituting the transport path has a predetermined curvature for curving the recording medium after passing through the fixing roller,
The image forming apparatus according to claim 1, wherein a curvature of the guide in the vicinity of the discharge roller is configured to be larger than a curvature of the vicinity of the fixing roller. The fixing unit includes:
A heating element that generates heat when energized;
A blocking means disposed above the fixing roller and configured to block power supply to the heating element at a predetermined temperature;
A pressure roller that is disposed at a position shifted to a side opposite to the direction of the supply roller from a position directly below the fixing roller, and is pressed toward the rotation center direction of the fixing roller,
4. The image forming apparatus according to claim 1, wherein the blocking unit is positioned on a plane orthogonal to a virtual straight line connecting the rotation centers of the fixing roller and the pressure roller. 5. The fixing unit includes a cover that covers the fixing roller and the blocking unit in a state where the pressure roller is exposed,
The image forming apparatus according to claim 4, wherein the cover supports the blocking unit on a plane orthogonal to a virtual straight line connecting the rotation centers of the fixing roller and the pressure roller. The image forming position positioned on the transport path is disposed at a position lower than the upper end of the transport path from the recording medium storage unit to the image forming position. An image forming apparatus according to claim 1. A laser beam is scanned by a polygon mirror, an electrostatic latent image is formed on the photoconductor by irradiating the scanned laser beam to the photoconductor, and the electrostatic latent image formed on the photoconductor is developed by a developer. An image forming apparatus that generates a visible image by developing and transfers the visible image generated on the photoreceptor to a recording medium at an image forming position,
A recording medium storage unit for storing the recording medium in a stacked state below the image forming apparatus;
A transport path for transporting the recording medium stored in the recording medium storage unit to the outside of the image forming apparatus via the image forming position, located above the recording medium storage unit;
A supply roller that is positioned above the vicinity of the end of the recording medium storage unit and supplies the recording medium stacked on the top of the recording medium storage unit to the transport path;
An upper portion of the supply roller is provided above the recording medium storage portion and disposed at a position close to the supply roller, and has at least a developer storage portion for storing the developer supplied to the photoreceptor. A process unit that can be taken out from the image forming apparatus in a substantially horizontal detaching direction,
A scanner unit that is disposed above the process unit and includes at least the polygon mirror;
With
The scanner unit has a taper shape with a small thickness on the supply roller side in the detaching direction so that the process unit can be taken out in the detaching direction.
A part of the transport path is formed in a region sandwiched between the process unit and the recording medium storage unit,
An image forming apparatus, wherein an image forming position positioned on the transport path is disposed at a position lower than an upper end of a transport path from the recording medium storage unit to the image forming position.

Images