JP2007128007A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of preventing an image carrier from being damaged because of collision with a sensor when a structural body for supporting the image carrier is attached/detached in such a state that the sensor is left on a main body housing side. <P>SOLUTION: In the image forming apparatus having the sensor 532 being an image control mark detection means opposed to the surface of the image carrier 5, the structural body 501 for supporting the image carrier is constituted separately from the structural body for supporting the sensor, and also it is constituted to be attached to/detached from an apparatus main body. The image forming apparatus is provided with a shutter mechanism 212 opening/shutting the sensor. It is provided with a part 540a projecting to the side of the image carrier 5 further than the shutter and its locking member 560 on the side of the structural body 540 for supporting the sensor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus including a sensor facing a surface of an image carrier.

  2. Description of the Related Art Conventionally, an image forming apparatus including a sensor facing the surface of an image carrier is known that includes a shutter mechanism to prevent the sensor surface of the sensor from being soiled (Patent Documents 1 and 2). Patent Document 1 describes an invention in which toner is prevented from being scattered on the surface of a sensor by shutter driving means using an electromagnetic solenoid. Japanese Patent Application Laid-Open No. 2004-228561 describes an invention about shutter driving by rotation of a driving roller.

Japanese Patent Laid-Open No. 2001-100597 JP 2004-138976 A

Although the shutter is effective in preventing contamination on the sensor surface, it must be positioned between the sensor surface and the image carrier, and thus there is a restriction on component arrangement. In particular, when attaching and detaching the unitized image carrier, there is a possibility that the surface of the carrier and the shutter may rub, or a member (gear or shaft joint) that drives the carrier may collide with the shutter and be damaged. Therefore, it is necessary to carefully attach and detach the unit. That is, when attaching and detaching the unit horizontally, the unit must be pulled out while maintaining the same posture, which places a burden on the user. In particular, when the unit is pulled out more than half, the center of gravity of the unit goes out of the case, so the part outside the case hangs down and the part remaining inside jumps up due to the reaction. There was a high possibility that it would occur.
It is also known to use a stepped screw to allow the shutter covering the sensor to slide and to prevent it from coming off. If the sensor is located on the image carrier and a shutter is present between them, consideration must be given to the arrangement of the step screws. That is, when the screw is fastened downward from above, the screw tip may face the image carrier, possibly damaging the surface of the image carrier. On the other hand, when fastening upward from below, the shutter slides while constantly rubbing against the large diameter part (collar neck part) of the stepped screw, so the screw may loosen over time, and it is necessary to bond it later with a screw lock etc. was there. In addition, when the shutter has a cleaning (sliding contact with a felt member, etc.) mechanism, the entire pressure of the shutter is pushed downward by the pressure contact force, and the contact between the shutter and the step screw large diameter portion (collar neck portion) becomes strong, It was supposed to spur loosening.
The present invention has been made in view of the above background, and a first object is to cause the image carrier to collide with the sensor when the structure supporting the image carrier is attached or detached while the sensor is left on the main body housing side. It is another object of the present invention to provide an image forming apparatus that can prevent damage.
A second object of the present invention is to provide an image forming apparatus capable of avoiding loosening of the screw accompanying the movement of the shutter even if a step is used for attaching the shutter.

In order to achieve the first object, the invention of claim 1 includes an image carrier and a structure that has an image control mark detection means facing the surface of the image carrier and supports the image carrier, In the image forming apparatus in which at least the structure that supports at least the sensor of the control mark detection means is configured separately, and at least the structure that supports the image carrier is configured to be detachable from the apparatus main body. A shutter mechanism that opens / closes the sensor is provided, and a portion that protrudes closer to the image carrier side than the shutter and its locking member is provided on the structure side that supports the sensor.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the protruding portion has the image over the entire width of the structure supporting the sensor in the attaching / detaching direction of the structure supporting the image carrier. The structure projecting toward the carrier and supporting the image carrier has a portion where the surface of the image carrier projects as a result of striking the projecting portion when the structure is inclined when the structure is detached. An image forming apparatus characterized in that a contact portion for preventing collision is provided.
According to a third aspect of the present invention, in the image forming apparatus of the first aspect, the sensor is disposed so as to face the surface of the image carrier from above, and between the sensor and the surface of the image carrier. A stepped screw is used as a locking member for the shutter, and the shutter is opened / shielded at a position higher than the large diameter portion in the height direction so that the shutter does not contact the large diameter portion of the stepped screw. A guide portion for guiding the shutter so as to move for the purpose is provided.
According to a fourth aspect of the present invention, in the image forming apparatus of the first aspect, the sensor is disposed so as to face the surface of the image carrier from above, and between the sensor and the surface of the image carrier. A stepped screw is used as a locking member for the shutter, and the shutter itself or a member integrated with the shutter is extended above the sensor so that the stepped screw is used downward, and the sensor is supported. The stepped screw is attached to the structure with the stepped screw, and the tip of the stepped screw turned downward is positioned above the sensor surface of the sensor.
In order to achieve the second object, an invention according to claim 5 is an image forming apparatus having an image carrier unit and at least one image control mark detection means in the vicinity thereof, and a detection surface of the image control mark detection means. A shutter mechanism that opens / closes the image sensor, the detection means is positioned above the image carrier, the shutter is positioned below the sensor detection surface, that is, above the image carrier, and is provided as a locking member for the shutter. The sliding region of the shutter that has a threaded screw and that contacts the shutter support when the shutter is opened / closed is positioned higher than the large diameter portion of the stepped screw (in the height direction). Therefore, it is characterized by providing a regulating means.
According to a sixth aspect of the present invention, there is provided an image forming apparatus having an image carrier unit and at least one image control mark detection unit in the vicinity thereof, and a shutter mechanism for opening / blocking a detection surface of the image control mark detection unit. The shutter is positioned below the sensor detection surface of the detection means, that is, above the image carrier, a stepped screw is used as a mounting member for the shutter, and the mounting direction of the stepped screw is increased with respect to the height direction. And the tip position of the stepped screw is positioned higher than the sensor detection surface.

According to the first to fourth aspects of the present invention, the image carrier can be prevented from colliding with the sensor and being damaged when the structure supporting the image carrier is attached or detached while the sensor is left on the main body housing side. effective.
According to the fifth to sixth aspects of the present invention, even if a step is used for mounting the shutter, there is an effect that it is possible to avoid the loosening of the screw accompanying the movement of the shutter.

A first embodiment of the present invention will be described with reference to FIGS. This embodiment is an example applied to an electrophotographic color printer as an image forming apparatus. Here, FIG. 1 is a longitudinal side view schematically showing the color printer of the present embodiment.
As shown in FIG. 1, four image forming units 3 (3Y, 3C, 3M, and 3K) and an optical writing device 4 that emits a light beam are provided at a substantially central portion inside the main body case 2 of the color printer 1. An intermediate transfer belt 5 that is an intermediate transfer member is disposed. Each image forming unit 3 is a part that forms an image (toner image) of a different color. In the description of this specification and the drawings regarding these image forming unit 3 and the components of the image forming unit 3, Y, The subscripts C, M, and K indicate yellow, cyan, magenta, and black colors, respectively. The main body case 2 includes an iron frame that functions as an image carrier holding member and an intermediate transfer belt holding member that is an intermediate transfer body holding member, and a resin cover attached to the frame. The unit 3, the optical writing device 4, and the intermediate transfer belt 5 are held by a frame. A unit having a frame for holding the intermediate transfer belt 5 is a unit that can be attached to and detached from the printer main body. This unit will be described in detail later.

  The four image forming units 3Y, 3C, 3M, and 3K have different colors of images formed because the colors of toners used are different, and the basic structure is the same. Each image forming unit 3 includes a photosensitive member 6 (6Y, 6C, 6M, 6K) that is an image carrier that is rotationally driven in the direction of an arrow, a charging unit 7, a developing unit 8, and a cleaning unit disposed around the photosensitive member 6. It is comprised by the part 9 grade | etc.,. The photoreceptor 6 is formed in a cylindrical shape and is rotationally driven by a drive source (not shown). A photosensitive layer is provided on the outer peripheral surface portion of the photosensitive member 6, and the outer peripheral surface 6 a which is the surface of the photosensitive member 6 is a scanned surface. When the light beam emitted from the optical writing device 4 is spot-irradiated on the outer peripheral surface 6 a of the photosensitive member 6, an electrostatic latent image corresponding to the image data is written on the outer peripheral surface 6 a of the photosensitive member 6. The charging unit 7 uniformly charges the outer peripheral surface 6 a of the photoconductor 6, and a non-contact type is used for the photoconductor 6. The developing unit 8 supplies toner to the photoconductor 6, and the supplied toner adheres to the electrostatic latent image written on the outer peripheral surface 6 a of the photoconductor 6, thereby causing the electrostatic latent image on the photoconductor 6. The toner image is visualized as a toner image, and a non-contact type is used for the photoreceptor 6. The cleaning unit 9 cleans residual toner adhering to the outer peripheral surface 6 a of the photoconductor 6, and a brush contact type in which a brush contacts the outer peripheral surface 6 a of the photoconductor 6 is employed.

  The intermediate transfer belt 5 is a loop belt formed using a resin film or rubber as a base, and a toner image formed on the photoreceptor 6 is transferred to the intermediate transfer belt 5. The intermediate transfer belt 5 is supported by rollers 11, 12, and 13 and is driven to rotate in the arrow direction. These rollers 11, 12, 13 are attached to the frame of the main body case 2, whereby the intermediate transfer belt 5 is attached to the frame of the main body case 2 via the rollers 11, 12, 13. Accordingly, the rollers 11, 12, and 13 are used as intermediate transfer body holding members that hold the intermediate transfer belt 5 together with the frame of the main body case 2. Here, the linear expansion coefficients of these rollers 11, 12, 13 are the same as the linear expansion coefficient of the main body case 2. On the inner peripheral surface side (inside the loop) of the intermediate transfer belt 5, four transfer rollers 14 that transfer the toner image on each photoconductor 6 onto the intermediate transfer belt 5 are arranged. On the outer peripheral surface side (outside the loop) of the intermediate transfer belt 5, a cleaning unit 15 that cleans residual toner, paper dust, and the like attached to the outer peripheral surface of the intermediate transfer belt 5 is disposed.

  Below the four image forming units 3 and the optical writing device 4 in the main body case 2, a paper feed cassette 16 on which recording media (paper sheets) are stacked and held is disposed. The recording media stacked and held in the paper cassette 16 are separated and fed in order from the highest one. In the main body case 2, a conveyance path 17 is formed through which a recording medium separated and fed from the sheet feeding cassette 16 is conveyed. On the conveyance path 17, a paper feed roller 18a, a registration roller 18b, a transfer roller 19, a fixing unit 20, a paper discharge roller 21 and the like are arranged. The registration roller 18b is a roller that is rotationally driven intermittently at a predetermined timing. By intermittently driving the registration roller 18b, the recording medium conveyed to the position of the registration roller 18b and stopped is sent to a transfer position sandwiched between the intermediate transfer belt 5 and the transfer roller 19, and recorded. In the process in which the medium passes through the transfer position, the toner image on the intermediate transfer belt 5 is transferred to the recording medium. The fixing unit 20 is a part that melts and fixes the toner image on the recording medium by applying heat and pressure to the recording medium on which the toner image is transferred. The recording medium fixed by passing through the fixing unit 20 is discharged onto a paper discharge tray 22 formed on the upper surface of the main body case 2 by a paper discharge roller 21.

  FIG. 2 is a longitudinal side view showing the optical writing device 4. The optical writing device 4 includes a housing 31 and an optical element holding member 32, and various optical elements described later are held in the optical element holding member 32. The housing 31 includes a housing body 31a having an upper surface opening and a lid cover 31b that closes an opening portion of the housing body 31a. Four openings 33 through which the light beam passes are formed in the lid cover 31b, and a dustproof member 34 that allows the light beam to pass therethrough and restricts intrusion of dust is attached to these openings 33. The optical element holding member 32 is housed in the housing 31 and is connected and fixed to the housing 31. The optical elements held by the optical element holding member 32 include four light source units (LD units) that oscillate light beams, and an optical deflector 42 that deflects and scans light beams from each light source unit in two symmetrical directions. , A scanning lens (fθ lens) 43 that forms an image of the deflected and scanned light beam on the photosensitive member 6 to a desired size, a synchronous detection optical system element that detects the scanning start timing of the light beam, and the photosensitive member by folding the light beam. 6 and the like, a folding mirror 45 (45a, 45b) and the like for leading to 6 are included. The optical deflector 42 includes a two-stage polygon mirror 49, a polygon motor 50 that rotates the polygon mirror 49, a polygon mirror 49, a soundproof glass 51 that covers the polygon motor 50, and the like.

  In such a configuration, the electrostatic latent image formed on each photoconductor 6 by the optical writing device 4 is developed with Y, M, C, and K toners of each developing unit 8 to form toner images of each color. The toner images on the respective photoreceptors 6 are visualized and sequentially transferred onto the intermediate transfer belt 5, and a color toner image is formed on the intermediate transfer belt 5. The color toner image on the intermediate transfer belt 5 is transferred to the recording medium when the recording medium passes through the position sandwiched between the transfer roller 19 and the intermediate transfer belt 5, and the recording medium on which the toner image is transferred is The paper is discharged onto the paper discharge tray 22 after being fixed by the fixing unit 20.

  FIG. 3 is a perspective view showing a schematic configuration of an intermediate transfer unit 500 including the intermediate transfer belt 5. The flexible loop belt 5 is stretched by rollers 11, 12, and 13. A unit housing 501 supports these rollers. The driving roller 11 that receives the driving force from the main body housing has a shaft joint 511 at the shaft core, and meshes with the joint 601 on the main body side plate 600 side shown in FIG.

  FIG. 4 is an exploded perspective view of the mechanism in the vicinity of the joint 601. A drive shaft 602 that holds the joint 601 is connected to the main body side plate 600 via a bearing 603, and further, rotation from a drive motor (not shown) is transmitted to a gear 604 that is coaxially fixed. One shaft end is locked to the second side plate 609 via a bearing 608.

  When the intermediate transfer unit 500 is detached from the main body, as shown in FIG. 5, the front door 610 is opened, and the unit is pulled out in a direction in which the shaft joint is separated. The positioning of the unit 500 and the main body is based on the drive shaft axis shown in FIG. 1, with a second positioning protrusion 520 on the back side of the main body and a third positioning protrusion 521 on the front side. It fits in. The unit 500 and the main body housing may be fixed by screwing in the vicinity of the third positioning portion 521, or by using a means for pressing the shaft joints together by another method (not shown) lock mechanism. It doesn't matter.

  The printer according to the present embodiment includes image control mark means (sensor) 530. This is to optically detect a mark which is a detection toner image formed on the intermediate transfer belt 5 for preventing color misregistration and the like. FIG. 6 is an exploded perspective view of the image control mark means 530 and its holding mechanism. The image control mark means (sensor) 530 is composed of several elements (532, 533, 534) provided on the substrate 531, and the substrate 531 is fixed to the brackets 540f, g with screws. In addition to the sensor 530, the bracket 540 includes a shutter 545 and a solenoid 546, and a tension spring 547 for the bracket 540 and the shutter 545. The spring 547 is stretched between a hook 545d on one end side of the shutter 545 and a hook 540k on the bracket side that are exposed from holes 540b, c provided in the bracket. The hook 545d on the other end side of the shutter 545 that protrudes from the hole 540c provided in the bracket is locked to a pin (not shown) provided on the solenoid 546 in the slit portion of the plunger. Note that members denoted by reference numerals 610 and 611 in FIG. 6 are members for fastening to the casing of the printer main body.

  The shutter 530 opens the elements (532, 533, 534) of the sensor 530 only at the timing of reading the image control mark recorded on the belt 5. At other timings, the element is positioned on the side where the element is closed by the tension spring 547. The shutter 545 is screwed to the bracket screw holes 540b and 540 with a stepped screw 560 from below.

  The protrusion 540a provided on the bracket is formed by feeding and bending downward over the entire width of the bracket, and its lower end edge is located below the lowest end of the stepped screw 560, as shown in FIG. The contact portion 525 provided on the image carrier unit frame and a slight gap are held. FIG. 7 is a cross-sectional view showing a facing region between the contact portion 525 and the projection 540a of the bracket. Although this figure is drawn as if they are in contact with each other, there is a gap between them. The projection 540a of the bracket is for preventing the surface of the intermediate transfer belt 5 as an image carrier from colliding with the shutter 545 and the stepped screw 560 when the intermediate transfer unit 500 is attached / detached. When the intermediate transfer unit 500 is tilted in the left-right direction by the amount of play or tilted in the front-rear direction of the printer, which is the attachment / detachment direction, when attached / detached, the projection 540a comes into contact with the contact portion 525 on the main body side. 5 and the shutter 545 are avoided.

Next, a printer according to a modification will be described with reference to FIGS.
This printer is a modification of the shutter holding mechanism, and is otherwise the same as the printer described above. FIG. 8 is an explanatory view of the stepped screw 560, and FIG. 9 is a cross-sectional view for explaining the shutter holding mechanism. In the printer, the lower surface of the shutter 545 is in contact with the upper surface of the large diameter portion 560a of the stepped screw. However, in the printer according to this modification, as shown in FIG. The lower surface of the shutter 545 floats from the upper surface of the large-diameter portion 560a of the stepped screw. Note that the right end side of the shutter 545 in FIG. 9 does not go down. This is because the hook 545e on one end side of the shutter 545 is locked to the plunger of the solenoid 546 as shown in FIG. Thus, the sliding region of the shutter that comes into contact with the receiving portion 540k as the shutter supporting portion when the shutter is opened / closed is positioned higher than the large-diameter portion 560a of the stepped screw (in the height direction). Thus, the loosening of the screw due to the sliding region coming into contact with the large diameter portion 540a is avoided.

  FIG. 10 shows a printer according to another modification. This printer is a modification of the shutter and its holding mechanism, and is otherwise the same as the printer. As shown in FIG. 10, the shutter 545 of the printer according to this modification is screwed with a stepped screw 560 from the upper side of the bracket 560. That is, the mounting direction of the stepped screw 560 is oriented to be fastened (with respect to the height direction) from above. Moreover, the tip position (screw tip) of the stepped screw 560 is positioned higher than the sensor detection surface. This also prevents loosening of the screw due to the shutter 545 touching the large diameter portion 540a of the stepped screw 560.

As described above, according to the image forming apparatus of the present embodiment, in the image forming apparatus having the image carrier unit and at least one image control mark detection unit in the vicinity thereof, the detection surface of the image control mark detection unit is opened / closed. By providing a portion having a shutter mechanism and projecting to the image carrier side with respect to the shutter and its locking member (screws), the shutter or stepped screws do not come into contact with the image carrier, and the image carrier The effect which can prevent the damage of a surface is raised.
A shutter mechanism for opening / blocking a detection surface of the image control mark detection unit; the detection unit is positioned above the image carrier; and the shutter is below the sensor detection surface, that is, above the image carrier. And has a stepped screw as the shutter locking member, and the sliding region of the shutter is positioned higher than the large diameter portion of the stepped screw (with respect to the height direction). By providing the regulating means, the shutter does not come into contact with the stepped screw large diameter portion, and the effect of eliminating the risk of loosening of the screw over time can be improved.
Further, the detection means is positioned above the image carrier, the shutter is positioned below the sensor detection surface, that is, above the image carrier, a stepped screw is provided as a locking member for the shutter, and the step is provided. The shutter 545 has a stepped screw because the screw mounting direction (with respect to the height direction) is tightened from above and the tip position (screw tip) of the stepped screw is positioned higher than the sensor detection surface. The large diameter portion 540a of 560 is not touched, and the risk of loosening of the screw over time is eliminated.

  In the above-described embodiment, the sensor is opposed to the intermediate transfer belt serving as the image carrier, but the present invention can also be applied to a sensor opposed to the photoconductor (drum or belt) as the image carrier.

1 is a cross-sectional view illustrating a schematic configuration of a color printer according to an embodiment. FIG. 3 is a longitudinal sectional view of the optical writing device of the printer. FIG. 2 is a perspective view illustrating a schematic configuration of an intermediate transfer unit of the printer. FIG. 3 is an exploded perspective view of a joint on the main body side plate side of the printer. FIG. FIG. 3 is an exploded perspective view of the image control mark unit and the holding mechanism of the printer. A sectional view of a part of the printer. Explanatory drawing of a stepped screw. FIG. 10 is a cross-sectional view of a part of a color printer according to a modification. FIG. 10 is a partial cross-sectional view of a color printer according to another modification.

Explanation of symbols

5 Intermediate Transfer Belt 500 Intermediate Transfer Unit 501 Unit Housing 532 Sensor 560 Stepped Screw 540 Bracket 540a Projection 545 Shutter

Claims (6)

A structure having an image carrier and an image control mark detection unit facing the surface of the image carrier, and supporting the image carrier, and a structure supporting at least a sensor of the control mark detection unit In an image forming apparatus configured and configured to be removable from at least a structure supporting the image carrier,
A shutter mechanism for opening / closing the sensor;
An image forming apparatus characterized in that a portion protruding toward the image carrier side of the shutter and its locking member is provided on the structure side supporting the sensor. The image forming apparatus according to claim 1.
The protruding portion protrudes toward the image carrier over almost the entire width of the structure supporting the sensor in the attachment / detachment direction of the structure supporting the image carrier, and the structure supporting the image carrier An image formation comprising a contact portion for preventing the surface of the image carrier from colliding with the projecting portion when the structure tilts when the structure is detached apparatus. The image forming apparatus according to claim 1.
The sensor is disposed so as to face the surface of the image carrier from above,
A stepped screw is used as a locking member of the shutter located between the sensor and the image carrier surface; and
In order to prevent the shutter from coming into contact with the large diameter portion of the stepped screw, a guide portion is provided for guiding the shutter so that the shutter moves for opening / shielding at a position higher than the large diameter portion in the height direction. An image forming apparatus. The image forming apparatus according to claim 1.
The sensor is disposed so as to face the surface of the image carrier from above,
Using a stepped screw as a locking member of the shutter located between the sensor and the surface of the image carrier,
The shutter itself or a member integrated with the shutter itself is extended above the sensor so that the stepped screw is used downward, and is attached to the structure supporting the sensor with the stepped screw.
An image forming apparatus, wherein the tip of the stepped screw that faces downward is positioned above the sensor surface of the sensor. In an image forming apparatus having an image carrier unit and at least one image control mark detection means in the vicinity thereof,
A shutter mechanism for opening / blocking the detection surface of the image control mark detection means;
The detection means is positioned above the image carrier,
Position the shutter below the sensor detection surface, that is, above the image carrier,
The shutter has a stepped screw as an engaging member of the shutter, and the sliding region of the shutter that contacts the shutter support when the shutter is moved to open / shut is set to a large size (with respect to the height direction). An image forming apparatus, characterized in that a regulating means is provided so as to be positioned higher than the diameter portion. In an image forming apparatus having an image carrier unit and at least one image control mark detection means in the vicinity thereof,
A shutter mechanism for opening / blocking the detection surface of the image control mark detection means;
Position the shutter below the sensor detection surface of the detection means, that is, above the image carrier,
A stepped screw is used as an attachment member of the shutter, the mounting direction of the stepped screw is oriented to be tightened from above with respect to the height direction, and the tip position of the stepped screw is positioned higher than the sensor detection surface. An image forming apparatus.

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