JP2014102471A - Toner image forming device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce variations in distance between a photoreceptor drum and a developing roller in assembly due to the accuracy of components, and reduce variations of a development gap in assembly or a twist of a toner image forming device, so as to obtain a stable development gap.SOLUTION: A toner image forming device includes: a toner image carrier device 410 that has a toner image carrier 1 carrying an electrostatic latent image, and a toner image obtained by developing the electrostatic latent image with toner; a developing device 3 that has a developer carrier 302 conveying a toner to develop the electrostatic latent image on the toner image carrier; and a gap holding member 420 that determines a development gap PG between the toner image carrier and the developer carrier. The toner image forming device further includes an urging member 430 that urges the toner image carrier device and the developing device in a direction to be separated from each other.

Description

  The present invention relates to a technique capable of effectively preventing variation in a developing gap between a photosensitive member and a developing roller in a toner image forming apparatus provided in an electrophotographic image forming apparatus.

In electrophotographic image forming apparatuses such as copiers, printers, and facsimile machines, an electrostatic latent image is formed by irradiating exposure light onto a uniformly charged photosensitive drum (toner image carrier). The electrostatic latent image is developed with toner supplied from a two-component developing type developing device to obtain a toner image. The toner image that moves as the photosensitive drum rotates is transferred onto a recording medium that has been supplied to the transfer position at a predetermined timing. The recording medium holding the toner image is conveyed to a fixing device and is pressurized while being heated, so that the toner image is fixed and then discharged outside the apparatus.
The developing device includes a developing roller (developer carrier) at a position facing the photosensitive drum with a predetermined gap therebetween, and the toner carried by the developing roller is transferred onto the electrostatic latent image on the photosensitive drum. Development is performed.

By the way, in a conventional two-component developing type developing device, a pair of gap holding members (face plates or side plates) or gap rollers are used as means for maintaining a constant gap (developing gap) between the developing roller and the photosensitive drum. It has been.
FIG. 10A is a schematic view of a gap management type toner image forming apparatus using a gap holding member (face plate).
The toner image forming apparatus 500 includes a photosensitive drum device (toner image carrier device) including a photosensitive drum (toner image carrier) 502 that carries an electrostatic latent image and a toner image obtained by developing the electrostatic latent image with toner. ) 501, a developing device 510 including a developing roller (developer carrying member) 511 that holds and conveys toner to the electrostatic latent image on the photosensitive drum 502, and the photosensitive drum device 501 and the developing device 510. A pair of left and right gap holding members (face plates) 520 that determine the facing distance (development gap) PG between the photosensitive drum 502 and the developing roller 511 by holding them simultaneously are provided.

The photosensitive drum 502 is rotatably supported by shaft mounting portions 503a as bearings provided on the photosensitive member casing 503 with shafts 502a at both ends thereof. Further, the developing roller 511 is fixedly supported by shaft attachment portions 512 a as shaft holes provided in the developing casing 512 with shafts 511 a at both ends thereof. The photosensitive drum shaft 502a protruding from the photosensitive member casing 503 and the developing roller shaft 511a protruding from the developing casing 512 are respectively supported by a shaft mounting portion 521 and a shaft mounting portion 522 provided in the gap holding member.
Each gap holding member 520 includes a shaft mounting portion 521 that rotatably supports both ends of the shaft 502a of the photosensitive drum, and a shaft mounting portion 522 that fixedly supports both ends of the shaft 511a of the developing roller. The distance between the shaft mounting portions 521 and 522 is constant. The gap holding member manages the developing gap by simultaneously supporting the photosensitive drum shaft and the developing roller shaft.
A gap roller (not shown) is a means for managing the development gap by being sandwiched between the photosensitive drum shaft and the developing roller shaft.

However, the conventional development gap management method has the following problems.
First, in the development gap management method using the gap holding member 520, as shown in FIG. 10B, the gap holding member 520 is inclined in the axial direction of the photosensitive drum or the like, whereby the photosensitive drum shaft 502a with respect to the gap holding member. In addition, the positional relationship between the developing roller shaft 511a may be in a non-orthogonal state or may be inclined from a target angle. In such a case, the development gap becomes narrower than the target value. That is, FIG. 10B shows an example in which the longitudinal positions of the photosensitive drum device 501 and the developing device 510 are deviated from the target, and the gap holding member is attached obliquely. When each device is screwed to the image forming apparatus main body in this state, the gap holding member for managing the developing gap between the developing roller and the photosensitive drum is attached obliquely, so the developing gap is more than intended. Will become narrower.

One of the causes of such a malfunction is the presence of play between the shafts 502a and 511a and the shaft mounting portions 503a and 512a provided in the photosensitive member casing 503 and the developing casing 512, respectively. The position of the developing roller and the photosensitive drum is not determined by this amount of play. Another cause is the presence of backlash between the shaft mounting portions 521 and 522 of the gap holding member and the shafts 502a and 511a, and the positions of the developing roller and the photosensitive drum by the backlash. Is that it is not decided. Another cause is that a gap occurs in the longitudinal positions of the photosensitive drum device 501 and the developing device 510 during assembly, and the gap holding member is set obliquely.
Further, as shown in FIG. 10C, when the toner image forming apparatus 500 in which the photosensitive drum device 501 and the developing device 510 are connected and fixed by the gap holding member 520 is set in the image forming apparatus main body, it is twisted and set. Even in the case of a jam, the development gap is likely to deviate from the target. That is, this example is a case where each gap holding member is twisted and set from a normal posture. In this case as well, the development gap is narrowed.

Further, the gap management method using the gap roller has a problem that the developing gap widens when the toner adheres to and adheres to the periphery of the gap roller.
Patent Document 1 discloses a configuration in which the shaft of the developing roller is urged in a direction away from the shaft of the photosensitive drum by a compression coil spring having one end supported on a pedestal fixed to a side plate (gap holding member). This is intended to be solved by energizing the play against the side plate of the developing roller and to keep the developing gap constant.
However, fluctuations in the development gap due to abnormalities in the mutual positional relationship (inclination of the face plate due to twisting or longitudinal displacement) that occur when the developing device or the photosensitive drum device is assembled to the image forming apparatus cannot be suppressed.

  The present invention not only determines the developing gap between the developing roller and the photosensitive drum by a gap holding member (face plate), but also supports the photosensitive drum device supporting the photosensitive drum and the developing roller. By biasing the positional relationship with the developing device in a direction away from each other (a direction orthogonal to the axial direction of the photosensitive drum or the like), the gap holding member is prevented from falling. In addition, rattling caused by component accuracy reduces assembly variation during assembly by separating the photosensitive drum and the developing roller by the biasing member, assembling variations in the developing gap, twisting of the toner image forming apparatus, etc. The purpose is to obtain a stable development gap.

  In order to solve the above problems, the invention according to claim 1 is a toner image carrier that supports an electrostatic latent image and a toner image carrier that carries a toner image obtained by developing the electrostatic latent image with toner. A developing gap between the toner image carrier and the developer carrier, and a developing device that supports the developer carrier for developing the electrostatic latent image on the toner image carrier. A toner image forming apparatus including a bias holding member that biases the toner image carrier device and the developing device in a direction of separating the toner image forming device.

  If the present invention is applied to a toner image forming apparatus (photosensitive drum apparatus and developing apparatus) of an image forming apparatus, the developing gap can be stabilized. That is, it is possible to suppress variations in the development gap when assembling the toner image forming apparatus. Further, it is possible to prevent the position of the developing device and the photosensitive drum device from being displaced in the longitudinal direction and to incline the gap holding member, so that the developing gap is stabilized. Further, it is possible to prevent the developing roller and the photosensitive device from being twisted to narrow the developing gap, and the developing gap is stabilized.

1 is a configuration explanatory diagram of a color image forming apparatus including a toner image forming apparatus according to an embodiment of the present invention. FIG. FIG. 2 is an explanatory diagram showing the arrangement of a photosensitive drum, a two-component developing device, and respective members around the photosensitive drum. It is a figure which shows magnetic flux density distribution formed in a developing roller. It is sectional drawing which shows the structure of a developing roller. FIG. 3 is a schematic view of the toner image forming apparatus as viewed from above. 1 is a schematic view of a toner image forming apparatus as viewed from the front. It is explanatory drawing which showed the dispersion | variation in the development gap after an apparatus assembly | attachment in the case where an urging member is present and not. FIG. 6 is a front view of a toner image forming apparatus according to another embodiment of the present invention. FIG. 6 is a front view of a toner image forming apparatus according to another embodiment of the present invention. (A) is a cross-sectional view showing a configuration of a toner image forming apparatus according to a conventional example, (b) is a cross-sectional view showing a state in which a deviation occurs in the longitudinal direction, and (c) is a diagram showing a gap holding member. It is a side view at the time of being twisted and set.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.
In the toner image forming apparatus according to the present invention, when managing the developing gap between the photosensitive drum and the developing roller connected by the gap holding member, the biasing member moves the photosensitive drum device and the developing device away from each other (photosensitive member). Urging in the direction perpendicular to the axial direction of the body drum or the like. Thereby, it is possible to prevent the positional relationship between the photosensitive drum and the developing roller from deviating due to component tolerances, backlash of the shaft mounting portion provided in the gap holding member, and the developing gap can be stabilized.

FIG. 1 is an explanatory diagram of a configuration of a color image forming apparatus including a toner image forming apparatus according to an embodiment of the present invention.
In this color image forming apparatus, an electrostatic latent image is formed by irradiating light from a light writing means onto a uniformly charged image carrier, and the electrostatic latent image is visualized by a developing device. 1 is an example of an electrophotographic image forming apparatus that obtains a recorded image by transferring to a sheet.
In the color image forming apparatus, a plurality of image forming units 17K, 17M, 17Y, and 17C are arranged in order from the upstream side in the moving direction (conveying direction) of the conveying belt 15 along the conveying belt 15 that conveys the transfer paper 8. The so-called tandem type.
Each of these image forming units is composed of a combination of a plurality of members and performs image formation. The image forming unit 17K forms black, the image forming unit 17M forms magenta, the image forming unit 17Y forms yellow, and the image forming unit 17C forms cyan. The image forming units have different colors. However, the internal configuration is the same for each image forming unit. Therefore, in the following, the outline of the image forming unit 17K will be described. For other image forming units, K added to the end of the reference numeral of each member in the image forming unit 17K, M for the image forming unit 17M, and the image forming unit 17Y. For Y, the image forming unit 17C is replaced with C, and description thereof is omitted.

The transport belt 15 is an endless belt that is rotatably supported by transport rollers 18 and 19, one of which is a driving roller and the other is a driven roller. Below the transport belt 15, paper feed trays 20, 21, and 22 that store the transfer paper 8 are provided.
For example, among the transfer sheets 8 stored in the sheet feed tray 20, the transfer sheet 8 at the uppermost position is sent out at the time of image formation and is temporarily put on standby by the registration roller 23. Next, the image forming unit 17 </ b> K sends out the image formation in synchronism with the image formation, and is attracted to the transport belt 15 by electrostatic attraction. In this way, the transfer paper 8 adsorbed to the conveyance belt 15 is conveyed to the first image forming unit 17K, where a black image is transferred.

The image forming unit 17K includes members having the same functions as those of the members described later with reference to FIG. The members having the same configuration functions are denoted by the same reference numerals as those in FIG. 2 with the suffix K, and are indicated by the photosensitive drum 1K, the charging device 2K, the developing device 3K, and the like. Although the conveyance belt 15 is omitted in FIG. 2, the transfer device 5 </ b> K is actually disposed on the back side of the upper stretched portion of the conveyance belt 15 as shown in FIG. 1. Further, writing means 16 is provided as means for irradiating the photosensitive drum 1 with exposure light L to form an electrostatic latent image.
When forming a color image, in the image forming unit 17K, the peripheral surface of the photosensitive drum 1K is uniformly charged by the charging device 2K in the dark, and then the exposure light corresponding to the black image from the optical scanning device 16K. L is exposed to form an electrostatic latent image. The electrostatic latent image is visualized with black toner in the developing device 3K, and a black toner image is formed on the drum-shaped photosensitive drum 1K.
The toner image is transferred onto the transfer paper 8 by the action of the transfer device 5K in alignment with the transfer paper 8 at a position where the drum-shaped photosensitive drum 1K and the transfer paper 8 on the conveying belt 15 contact each other, so-called transfer position. A monochrome (black) image is formed on the transfer paper 8. After the transfer, unnecessary toner remaining on the peripheral surface of the photosensitive drum 1K is removed by the cleaning device 6K to prepare for the next image formation.

In this way, the transfer paper 8 on which the single color (black) is transferred by the image forming unit 17K is transported to the next image forming unit 17M by the transport belt 15. In the image forming unit 17M, the magenta toner image formed on the photosensitive drum 1M by the same process as that in the image forming unit 17K is superimposed and transferred onto the black toner image on the transfer paper 8.
The transfer paper 8 is further conveyed to the next image forming unit 17Y, and the yellow toner image formed on the photosensitive drum 1Y in the same manner is superimposed on the black and magenta toner images already formed on the transfer paper 8. Transcribed. Similarly, in the next image forming unit 17C, a cyan toner image is transferred and overlapped to obtain a full color image.
The transfer paper 8 on which the full-color superimposed image is formed in this way passes through the image forming unit 17C, is peeled off from the conveyance belt 15, and then fixed by the fixing unit 24 while passing between the pair of fixing rollers. The paper is discharged to the paper discharge tray 25.

FIG. 2 is an explanatory view showing the arrangement of the photosensitive drum (photosensitive member) 1, the two-component developing device 3, and the surrounding members. The photosensitive drum 1 is rotationally driven in a clockwise direction as indicated by an arrow. The charging device 2 is disposed at an approximately 11 o'clock position on the top of the photosensitive drum 1 in terms of a clock face. In this example, the charging device 2 is composed of a rotating body that rotates at the same speed as that of the photosensitive member.
After the surface of the photosensitive drum 1 is uniformly charged in the dark by the charging device 2, an electrostatic latent image is formed by receiving exposure light L from writing means (not shown). This electrostatic latent image moves downstream as the photosensitive drum 1 rotates and reaches the developing device 3.

The developing device 3 includes a supply chamber conveying member 304 and a collection chamber conveying member 305 for agitating and conveying a developer (carrier, toner) 320 and a rotating member such as a developing roller 302 and other members in a casing 301.
The developing roller 302 is disposed in close proximity so as to form a developing nip region A by being opposed to the photosensitive drum 1 at a position between 2 o'clock and 3 o'clock (position at 2:30). A portion of the casing 301 corresponding to the portion facing the photosensitive drum 1 is opened to expose the developing roller 302.
The developer 320 in the casing 301 is conveyed to the development nip area A by the developing roller 302. The toner in the developer 320 adheres to the electrostatic latent image formed on the surface of the photosensitive drum 1 in the development nip region A and is visualized as a toner image.

The toner image moves downstream as the photosensitive drum 1 rotates and reaches the transfer device 5. The transfer device 5 is disposed at the bottom of the photosensitive drum 1 at the 6 o'clock position. In this example, the transfer device 5 is composed of a rotating body. A region where the photosensitive drum 1 and the transfer device 5 face each other is referred to as a transfer region B.
The toner image on the photosensitive drum 1 is transferred to the transfer paper 8 in the transfer region B and becomes an image on the transfer paper 8. It can also be applied to an intermediate transfer belt method in which the toner on the photosensitive member is temporarily transferred to an intermediate transfer member (such as an intermediate transfer belt) and then the multicolor toners are transferred to a transfer sheet in a batch. In the region B, the toner on the photosensitive member is transferred to the intermediate transfer member (intermediate transfer belt).

After the transfer, the photosensitive drum 1 moves downstream with the rotation of the photosensitive drum 1 and reaches the cleaning device 6.
The cleaning device 6 is arranged at the 10 o'clock position. The cleaning device 6 uses a cleaning blade 601 to remove toner remaining on the surface of the photosensitive drum 1 without being completely transferred onto the transfer paper. The surface of the photosensitive drum 1 that has passed through the cleaning device 6 is then uniformly charged by the charging device 2 and the next image forming process is repeated.
The developing device 3 includes a developing roller 302, a supply chamber conveying member 304, a recovery chamber conveying member 305, and a developer regulating member 303 inside the casing 301, and the developer 320 is agitated and conveyed to circulate.

FIG. 3 is a diagram showing a magnetic flux density distribution formed on the developing roller. As shown in the figure, the developing roller 302 has a magnet roller 302d in which a plurality of magnets MG (only one is shown in order to prevent complication of the drawing) arranged in the circumferential direction. A cylindrical sleeve 302c is configured to rotate integrally with the rotating shaft 302e.
The sleeve 302c is made of a nonmagnetic metal such as aluminum. The magnet roller 302d is fixed to an immovable member such as the casing 301 so that each magnet MG faces a predetermined direction, and the sleeve 302c rotates around the periphery of the magnet roller MG to convey the developer 320 attracted by the magnet MG. .
In the cross-sectional view of FIG. 4 showing the structure of the developing roller 302, the developing roller 302 is mainly composed of a fixed shaft 302a fixed to a casing 301 as a stationary member, and a magnet roller 302d having a cylindrical shape integrated with the fixed shaft 302a. The sleeve 302c covers the periphery of the magnet roller 302d through a gap, and the rotating shaft 302e is integrated with the sleeve 302c. The rotation shaft 302e is rotatable with respect to the fixed shaft 302a via a bearing 302f, and the rotation shaft 302e is driven to rotate by receiving power from a rotation driving means (not shown).

A plurality of magnets MG are fixed to the outer periphery of the magnet roller 302d at a predetermined interval as shown in FIG. The sleeve 302c is rotated around these magnets MG.
These magnets MG are for forming a magnetic field so that the developer can be spiked on the peripheral surface of the sleeve 302c, and can be cut off. Magnetic carriers are gathered to form a magnetic brush along the normal magnetic field lines emitted from these magnets MG.
The developing roller 302 and the photosensitive drum 1 are not in direct contact with each other in the developing nip region A (see FIG. 2), but are opposed to each other while maintaining a developing gap GP at a constant interval suitable for development.
On the developing roller 302, the developer 320 is raised and brought into contact with the photosensitive drum 1, whereby toner is attached to the electrostatic latent image on the surface of the photosensitive drum 1 to be visualized.

In the developing device 3, as shown in FIG. 3, a grounding bias power source (not shown) is connected to the fixed shaft 302a. The voltage of the power source VP connected to the fixed shaft 302a is applied to the sleeve 302c through a conductive bearing (not shown) and a conductive rotating shaft 302e. On the other hand, the lowermost conductive support constituting the photosensitive drum 1 is grounded.
Thus, an electric field for moving the toner separated from the carrier to the photosensitive drum 1 side is formed in the developing nip region A, and the potential difference between the sleeve 302c and the electrostatic latent image formed on the surface of the photosensitive drum 1 is formed. Thus, the toner is moved toward the photosensitive drum 1 side.

Next, FIG. 5 is a schematic view of the toner image forming apparatus as viewed from above.
The toner image forming apparatus 400 of the present invention includes a photosensitive drum device (toner image) including a photosensitive drum (toner image carrier) 1 that carries an electrostatic latent image and a toner image obtained by developing the electrostatic latent image with toner. A developing device 3 including a carrier device) 410, a developing roller (developer carrier) 302 that holds and conveys toner to the electrostatic latent image on the photosensitive drum 1, and develops the photosensitive drum device 410 and the developing device. 3, a gap holding member 420 that determines the distance between the toner image carrier and the developer carrier, a biasing member 430 that biases the photosensitive drum device and the developing device in a direction of separating, It is characterized by having.
A pair of gap holding members 420, also referred to as face plates, are provided with a shaft mounting portion 421 that rotatably supports both ends of the photosensitive drum shaft 1a, and a shaft mounting that fixedly supports both ends of the developing roller shaft 302a. Part 422.

The developing roller and the photosensitive drum are set by inserting the respective shafts into the shaft mounting portions 421 and 422 of the gap holding member (face plate) 420, thereby developing according to the distance between the two shaft mounting portions of the gap holding member. The gap is managed. The position of the developing device 3 is determined by the developing roller 302 and the gap holding member 420, and the position of the photosensitive drum device is determined by the photosensitive drum 1 and the gap holding member 420.
When assembling the image forming apparatus main body, after the developing device 3 and the photosensitive drum device 410 are assembled, the two gap holding members 420 are set, and the position is fixed by screwing.

However, in the developing device, the developing roller shaft 302a is supported in a non-rotatable manner by the shaft mounting portion 301a provided in the casing 301, and the positions of both parts are equal to the backlash between the shaft mounting portion 301a and the developing roller shaft 302a. The relationship can be indeterminate. Similarly, there is a backlash between the developing roller shaft 302a and the shaft attaching portion 421 of the gap holding member, and the position of the developing roller can be uncertain with respect to the gap holding member. Such an indeterminate element is the play between the shaft mounting portion 411a provided on the casing 411 of the photosensitive drum device and the photosensitive drum shaft 1a, and between the photosensitive drum shaft and the shaft mounting portion 422 of the gap holding member. It also occurs due to backlash.
That is, the developing roller shaft and the photosensitive drum shaft are not only supported by the shaft mounting portion 301a and the shaft mounting portion 411a provided in the respective casings 301 and 411, but also the shaft mounting portion 421 provided in the gap holding member, the shaft The mounting portion 422 is also supported. The shaft mounting portion is disposed in each casing or the gap holding member 420 and supports each shaft end portion in a fixed or rotatable manner. A backlash due to component tolerances may be formed between the shaft mounting portions and the shafts 302a and 1a, and the development gap PG may become non-uniform due to the backlash.

In order to deal with such a problem, in the present invention, an urging member 430 that constantly urges the developing device and the photosensitive drum device in a direction to separate them is provided between the casings 411 and 301. The urging direction by the urging member is in a plane including the developing roller shaft and the photosensitive drum shaft, and is a direction orthogonal to each axis.
The casing 411 is a casing that directly supports the photosensitive drum, and the casing 301 is a casing that directly supports the developing roller.

Of course, the urging member 430 is disposed at a position that does not interfere with the development gap. In the plan view of FIG. 5, one urging member 430 is arranged between the casings 411 and 301 corresponding to both axial ends that avoid the development gap. In this case, each urging member 430 is arranged at an appropriate position in the middle in the height direction of each casing 411, 301 so that the pressure balance is stable. Alternatively, as illustrated in FIG. 6, a plurality of urging members may be arranged in the height direction of the casings 411 and 301.
Note that an elastic body or a spring is used as the biasing member 430. In addition, if the urging member is in the image forming area, it may interfere with image formation. Therefore, the urging member is preferably arranged outside the image forming area. In this embodiment, a rubber-like elastic body such as rubber or elastic resin is used as the elastic member.

A spring-like elastic body such as a coil spring or a leaf spring can be applied as long as the photosensitive drum device and the developing device can be energized.
If the urging forces of the plurality of urging members 430 vary or the urging position and the urging direction are not appropriate, the urging directions of both devices may not be constant.
In the example of FIG. 5, the urging members 430 are provided one by one at the left and right axial positions (between the casings) of the toner image forming apparatus 400. However, for example, when one gap holding member 420 is fixed to the main body of the image forming apparatus with a screw or the like, the biasing member does not have to be disposed on the fixed gap holding member side. Thus, when one gap holding member is fixed without rattling or twisting, the other biasing member may be provided only between the casings on the gap holding member side that are not screw-fixed.

Next, FIG. 6 is a schematic view of the toner image forming apparatus as viewed from the front.
A gap holding member 420 indicated by a chain line manages the distance between the photosensitive drum 1 and the developing roller 302 (developing gap). In this example, the urging member 430 is disposed at two locations, upper and lower, near both ends of the developing device 3 and the photosensitive drum device 410 in the axial direction. Since the developing device and the photosensitive drum device are subjected to a force away from the biasing member before the gap holding member is attached, the maximum distance between the devices is ensured even if there is a tolerance or backlash in the shaft attachment part or other parts. A gap holding member is attached and fixed at a widened separation position.
In FIG. 6, the urging members are arranged at two positions in the upper and lower positions. However, as long as there is no backlash such as the shaft mounting portion and the gap holding member can be prevented from being inclined, the position may be one instead of two. Absent.

Next, FIG. 7 is an explanatory diagram showing the variation in the development gap after assembling the apparatus with and without the urging member.
The vertical axis in FIG. 7 represents the development gap standard deviation when the operation of assembling the same toner image forming apparatus is repeated 10 times.
When the photosensitive drum device, the developing device, and the gap holding member were assembled to the image forming apparatus main body without the urging member, the standard deviation of the developing gap was about 10 μm. However, by attaching the biasing member, the inclination and twist of the gap holding member were eliminated, and the standard deviation of the developing gap was improved to 3 μm or less.

Next, FIG. 8 is a front view of a toner image forming apparatus according to another embodiment of the present invention.
The toner image forming apparatus 400 is different from the above-described embodiment in that the gap holding member 420 is provided with two elliptical support holes 425 and 425, and further, a pin 427 is provided at an appropriate position below the casing 411 of the photosensitive drum of the developing roller. The pin 427 is protruded at an appropriate position below the casing 301 of the developing roller. The pins 427 and 427 are inserted into the support holes 425 and 425, respectively. Further, an urging member 430 is disposed between upper casings on the opposite side to the lower portions where the pins 427 and 427 are provided, and urged in a direction to separate the casings.

In this configuration example, the shaft mounting portions 421 and 422 provided on the gap holding member 420 support the developing roller shaft 302a and the photosensitive drum shaft 1a, thereby determining the distance between the shafts. Further, the developing roller shaft and the photosensitive drum shaft can be positioned by supporting the pins 427 and 427 in the support holes 425 and 425 serving as positioning references.
For this reason, in this embodiment, it is sufficient to arrange the required number of urging members 430 between the upper parts of the casings, and it is not necessary to arrange them in the lower parts between the casings.
Of course, the support holes 425 and 425 and the pins 427 and 427 as positioning references may be arranged at the upper part of each casing, and the urging member may be arranged at the lower part of the casing.

Next, FIG. 9 is a front view of a toner image forming apparatus according to another embodiment.
The toner image forming apparatus 400 differs from the above embodiment in that the urging member 430 is not disposed between the casing 301 and the casing 411 (between the opposing surfaces), but is disposed at another part of each casing. The distance between the casings is separated.
In this example, each urging member 430 is disposed (fixed) on the outer side surface (the side opposite to the opposing surface) of each casing 301 and 411, and the other end portion of each urging member is a fixing portion (non-moving) of the image forming apparatus main body. Part). And each urging | biasing member is comprised so that it may pull in the direction which separates each karing mutually.
In addition, the position where the urging member 430 is attached to each casing may be, for example, the upper surface, the lower surface, and other side surfaces of each casing other than the outer surface as illustrated. In this case, protrusions are provided on the upper surface, the lower surface, and the side surfaces, and an urging member is disposed between the protrusion and the fixing portion.
With this configuration, the photosensitive drum device and the developing device can be separated in the farthest positional relationship by the force of the urging member.

  As described above, in the present invention, the photosensitive drum device (toner image carrier device) supporting the photosensitive drum and the developing device supporting the developing roller are away from each other, that is, the photosensitive drum or the like. By energizing in a separating direction orthogonal to the axial direction, the photosensitive drum and the developing device are in the most separated positional relationship. In other words, if there is a variation in accuracy of components, looseness in assembly, misalignment between the photosensitive drum and the developing roller during assembly, twisting or tilting of the gap holding member, etc. It can not be. For this reason, there exists a possibility that a development gap may become narrow.

In the present invention, since the photosensitive drum device and the developing device are separated from each other by the force of the biasing member, the positional deviation between the photosensitive drum and the developing roller during assembly, the twist and the inclination of the gap holding member, and the like. It will be resolved. When the developing device and the photosensitive drum device are separated as much as possible, the positional relationship between the developing roller and the photosensitive drum is naturally stabilized at the farthest positional relationship. The developing roller and the photosensitive drum are most separated from each other in a state where the developing roller and the photosensitive drum are biased in a direction in which they are separated from each other while being set on the gap holding member. That is, in this state, it is fixed in a state where the play between the developing roller and the gap holding member and the play between the photosensitive drum and the gap holding member are eliminated. Therefore, the development gap is stabilized. Further, even when a force that twists with an external force is applied when the toner image forming apparatus is set on the image forming apparatus main body, a force against the twist is exerted by the urging force from the urging member. Even after setting, the development gap can be stabilized.
In the above-described embodiment, the present invention is applied to the two-component developing system developing device, but the present invention can also be applied to a one-component developing system that forms a toner image by managing the gap between the developing roller and the photosensitive member.

  DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum (toner image carrier), 1a ... Photosensitive drum axis | shaft, 1K ... Photosensitive drum, 1M ... Photosensitive drum, 1Y ... Photosensitive drum, 2 ... Charging device, 3 ... Developing device, 5 ... Transfer Device 6 ... Cleaning device 8 Transfer paper 15 Transport belt 16 Writing means 16K Optical scanning device 17C Image forming unit 17K Image forming unit 17M Image forming unit 17Y Image Forming unit, 18 ... conveying roller, 20 ... feed tray, 23 ... registration roller, 24 ... fixing unit, 25 ... discharge tray, 301,411 ... casing, 302 ... developing roller (developer carrier), 302a ... developing Roller shaft, 302c ... sleeve, 302d ... magnet roller, 302e ... rotating shaft, 302f ... bearing, 303 ... developer regulating member, 304 ... supply chamber transport member, 305 ... collection chamber transport member, 320 Developer, 400 ... toner image forming apparatus, 410 ... photosensitive drum unit (toner image bearing member unit), 420 ... gap retaining member, 421 ... shaft mounting portion, 422 ... shaft mounting portion, 430 ... urging member

JP 2009-288279 A

Claims (6)

A toner image carrier device supporting a toner image carrier that carries an electrostatic latent image and a toner image obtained by developing the electrostatic latent image with toner, and transporting toner to the electrostatic latent image on the toner image carrier A toner image forming apparatus comprising: a developing device that supports a developer carrying member to be developed; and a gap holding member that determines a developing gap between the toner image carrying member and the developer carrying member.
A toner image forming apparatus comprising an urging member that urges the toner image carrier device and the developing device in a direction to separate them.   The toner image forming apparatus according to claim 1, wherein the urging member is disposed between opposing surfaces of the toner image carrier device and the developing device.   The toner image forming apparatus according to claim 1, wherein the urging member is a rubber-like elastic body.   The toner image forming apparatus according to claim 1, wherein the biasing member is a spring-like elastic body.   The toner image forming apparatus according to claim 1, wherein the urging member is disposed at a position avoiding the development gap.   An image forming apparatus comprising the toner image forming apparatus according to claim 1.

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