JP2513326Y2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a copying machine in which a developing unit having a developer carrying member carrying a developer is held so as to be able to come into contact with and separate from a latent image carrying member. And an image forming apparatus such as a printer.

[Conventional technology]

In image forming apparatuses such as copiers, printers and facsimiles, for example, a non-contact developing method in which a developer carrying member made up of a developing roller and a latent image carrying member made up of a photosensitive drum are arranged to face each other with a predetermined gap, or both. There is known an apparatus that employs a contact development method in which the toners are brought into contact with each other via a developer. In either case, the relative positions of the developer bearing member and the latent image bearing member deviate from each other. It is necessary to set so as to have a uniform positional relationship at all the positions along the axial direction.

For this reason, an image forming apparatus is disclosed in, for example, Japanese Patent Laid-Open No. 62-81650.
As shown in FIG. 10 of the publication, the developing unit 50
An urging member 53 formed by, for example, a leaf spring is provided on the right side surface of a supporting member 52 that rotatably supports the developing roller 51 of FIG. 10, and the entire developing unit 50 is left in FIG. 10 by the urging force. There is one in which the developing roller 51 is pressed against the photosensitive drum 55 by urging it toward one side.

In addition, a compression coil spring is used as an urging member to similarly press and urge the entire developing unit to press the developing roller against the photosensitive drum (Japanese Patent Laid-Open No. 62-192771).
Japanese Patent Publication) is also proposed.

[Problems to be solved by the device]

However, such a biasing member such as a leaf spring or a compression coil spring is used to directly bias the side surface of the supporting member supporting the developing roller to bias the developing roller at all positions along the axial direction of the photosensitive member. When it is attempted to set a uniform positional relationship with the drum, two or more urging members are normally used.

Therefore, for example, when two urging members are used, it is necessary to use the same spring constant in order to make the pressing force uniform. However, it is difficult to make them the same because the individual parts have variations within unavoidable tolerances in manufacturing the parts.

Also, sometimes it is desired to adjust the pressing force of the developing roller against the photosensitive drum, but in the case of the conventional image forming apparatus as described above, this can be done unless the biasing member such as the spring is replaced. There was also the inconvenience of not being able to do it.

The present invention has been made in view of the above problems, and a biasing member allows a developer carrying member such as the developing roller to be uniformly positioned with respect to a latent image carrying member such as the photosensitive drum. It is an object of the present invention to press so as to be in a relationship so that the pressing force can be easily adjusted.

[Means for solving the problem]

In order to achieve the above object, the present invention provides a developing unit having a developer carrying member carrying a developer, and an electrostatic latent image carried on the surface by the developer being adhered by the developer carrying member. An image forming apparatus, comprising: a latent image carrier for making a visible image, wherein the developing unit is held by a holding member so that the developing unit can come into contact with and separate from the latent image carrier. On a side surface of the support member that rotatably supports the body on the side opposite to the latent image carrier, a pair of engaging members whose amount of protrusion with respect to the side surface can be adjusted are spaced in the axial direction of the developer carrier. A pressing member that is provided to correspond to the pair of engaging members and presses a pair of pressing members interlocking with the holding member by one biasing member to bring the force point portions into contact with and press the engaging members. A mechanism is provided, and the pressing mechanism supports the developer. The is obtained so as to uniformly pressed to the latent image bearing member.

[Action]

According to the image forming apparatus configured as described above, the force application points of the pair of pressing members of the pressing mechanism that is interlocked by one urging member and the latent image carrier of the supporting member that supports the developer carrier. A pair of engaging members provided at intervals on the opposite side surface in the axial direction of the developer carrying member respectively abuts and presses them, and the developer carrying member is urged by the urging force of the one urging member. Since the latent image carrier is pressed through the pair of pressing members, the pair of engaging members, and the supporting member, the biasing force does not vary as in the case of using a plurality of biasing members. The relative position along the axis of the carrier and the latent image carrier has a uniform positional relationship without deviation.

In addition, since the pair of engaging members can adjust the amount of protrusion with respect to the side surface of the support member, changing the amount of protrusion facilitates the pressing force of the developer carrier to the latent image carrier side. It can also be adjusted to.

〔Example〕

An embodiment of the present invention will be specifically described below with reference to the drawings.

FIG. 1 is a configuration diagram showing the vicinity of a developing unit of a laser printer as an image forming apparatus embodying the present invention, and FIG. 2 is an overall configuration diagram showing the same laser printer as a whole.

In this laser printer, the recording paper 2 fed from the paper feeding device 1 shown in FIG. 2 in the arrow A direction is rotatable in the drum-shaped arrow direction at a timing by the registration roller pair 3. It is conveyed to the latent image carrier composed of the photosensitive drum 4.

The surface of the photoconductor drum 4 is charged by the charging charger 5, and the laser beam from the laser optical system 6 is applied to the surface to form an electrostatic latent image.

The latent image is visualized with toner T when passing through the developing roller 7 which serves as a developer bearing member of the developing unit 8, and the visible image is conveyed to the photosensitive drum 4.
Is transferred onto the recording paper by the action of the transfer charger 9, and the visible image on the recording paper is fixed by the fixing device 11.

Then, the recording paper 2 coming out of the fixing device 11 is the printer body.
The paper is ejected in the direction of arrow B to the paper ejection unit 12 provided on the upper surface of 10.

On the other hand, the photosensitive drum 4 after the transfer of the visible image is
The residual toner on the surface is removed by the cleaning device 13 having the cleaning blade 14, and the charge is removed by the charge removing device 17, and the removed toner is impeller.
The toner is collected and stored in the toner collecting chamber 16 by 15.

Next, the developing unit 8 will be described in detail with reference to FIG.

The developing unit 8 includes a case 21 for accommodating the toner T which is a developer, the above-mentioned developing roller 7 serving as a developer carrying member for carrying the toner which is arranged to face the photosensitive drum 4, and the developing roller 7 on the developing roller 7. It has a regulating blade 19 for making the toner layer thickness uniform and thin, a supply roller 23 for supplying toner to the developing roller 7, and an agitator 30 for stirring the toner T in the case 21.

The developing roller 7 is rotatably supported by the shaft 7a on the front and rear side plate portions 21a of the case 21, which also functions as a supporting member, and the toner is attached to the adjacent photosensitive drum 4 (latent image carrier). T is attached to make the electrostatic latent image carried on the surface visible.

The developing unit 8 as a whole is supported by the image forming unit case 22 serving as a holding member through the bearing (not shown) of the shaft 7a of the developing roller 7 (see also FIG. 4), and the developing unit 8 is moved relative to the photosensitive drum 4. It is held so that it can be moved in and out (movable to the left and right in FIG. 1).

Further, the regulation blade 19 is attached to the case 21, and the toner cartridge 32 is detachably attached to the case 21 and is attached until the toner remaining in the case 21 becomes low. The toner cartridge is replaced with a new toner cartridge containing a new toner inside, and the case 21 is replenished with toner.

In the developing operation by the developing unit 8, the toner T in the case 21 rotates in the direction shown by the arrow in FIG.
Is supplied to the developing roller 7 rotating in the counterclockwise direction, the toner T is thinned by the regulation blade 19, and the toner T is conveyed to a region where the photoconductor drum 4 and the developing roller 7 face each other, and is exposed. The electrostatic latent image on the body drum 4 is visualized.

The developing roller 7 is made of urethane rubber, for example, and has JIS hardness A.
The mold is made of an elastic material of about 30 °, a film layer of conductive particles is formed on the surface layer, and a predetermined pressure suitable for development is applied to the photosensitive drum 4 as shown in FIG. It is pressed and deformed by the deformation amount d in the pressed state.

The regulating blade 19 is formed of, for example, silicon rubber such as methyl vinyl polysiloxane, or other resin material, and the front and rear ends in FIG. 1 are vertically moved by guide grooves (not shown). It is slidably guided and is urged downward by a spring 38 provided between the spring receiving portion 21b formed above the case 21 and the lower end edge of the case 38 is brought into contact with the developing roller 7.

In this laser printer, the latent image carrier composed of the photosensitive drum 4 and its associated parts such as the cleaning device 13 and the charging charger 5 are configured as one latent image carrier unit, and the latent image carrier unit is formed. The developing unit 8 and the developing unit 8 are detachably attached to the image forming unit case 22, respectively.

Next, a pressing mechanism for uniformly pressing the developing roller 7 against the photosensitive drum 4 will be described with reference to FIGS. 4 to 6 in addition to FIG.

As shown in FIG. 1, on the side surface 21c on the right side of the figure on the side opposite to the photosensitive drum 4 of the case 21, by loosening and re-tightening the set screw 18, 18 once for the protrusion amount L with respect to the side surface 21c. A pair of adjustable engaging members 24 and 25 which are clearly shown in FIGS. 4 to 6 are provided at intervals in the axial direction of the developing roller 7.

Then, a pair of pressing members 27, 28 are interlocked with the image forming unit case 22 corresponding to the pair of engaging members 24, 25 by a tension coil spring 26 which is one urging member, and the fifth A pressing mechanism 20 is provided which presses the force points 27a and 28a shown in the drawing against the end surfaces of the engaging members 24 and 25, respectively.

That is, as shown in FIG. 5, the pair of engaging members 24, 2
5, a pair of pressing members 27 and 28 are formed in L-shapes having the same size, respectively, and are arranged so as to be opposed to each other in a symmetrical positional relationship, and they are imaged by supporting pins 29 and 29. Support parts 22a, 22 formed on the inner surface of the unit case 22
It is swingably supported on b, and tension coil springs 26 are respectively attached to inner ends 27c and 28c of the pressing members 27 and 28, respectively, to pull and bias them inward, and force points 27a and 28
At a, the engaging members 24 and 25 are pressed in the direction of arrow C, respectively.
Each of them is pressed by F ₁ and F ₂ , so that the developing roller 7 is pressed toward the photosensitive drum 4 side via the case 21.

FIG. 6 is a perspective view showing a mechanism capable of adjusting the amount of protrusion of the engaging member with respect to the side surface of the case.
Two guide rods 31 and 31 are vertically fixed to 21c so as to correspond to the respective force point portions 27a and 28a (Fig. 5) of the pressing members 27 and 28, and the guide rods 31 and 31 have block-shaped engagement. Sliding holes 2 formed in the mating members 24 and 25 along the longitudinal direction, respectively
4a and 25a are fitted so as to be movable in the direction of arrow D.

The screw holes 24b, 2 which are penetrated from the respective upper surfaces of the engaging members 24, 25 toward the sliding holes 24a, 25a in the fitted state
By screwing the set screws 18 and 18 to 5b,
The engaging members 24 and 25 are fixed at predetermined positions.

With such a configuration, the case 21 is constantly pressed by the pressing mechanism 20 toward the photosensitive drum 4 side (the direction of arrow C in FIG. 5), and the pressing mechanism is the same as that of the tension coil spring 26 shown in FIG. The tensile force acts on each one end 27c, 28d of the pressing members 27, 28 with the same force, and the pressing force causes the pressing members 27, 2 to
8 swings in the directions of arrows E and F with each support pin 29 as a fulcrum.

Accordingly, the force application points 27a and 28a of the pressing members 27 and 28 are
However, the engaging members 24 and 25 are respectively pressed in the arrow C direction by the pressing forces F ₁ and F ₂ corresponding to the urging force (tensile force) of the tension coil spring 26.

And the pressing forces F ₁ and F ₂ are
Since the force is exerted by 26, if the pressing members 27 and 28 are formed to have the same dimensions (dimensions of portions related to the action of force), they are substantially the same.

Further, in this embodiment, the engaging members 24 and 25 are attached to the case 21.
Since the protrusion amount (L in FIG. 1) can be adjusted with respect to the side surface 21c of the developing roller 7, the pressing force of the developing roller 7 against the photosensitive drum 4 does not change the tension coil spring 26 to one having a different spring constant. And it can be easily adjusted.

FIGS. 7 and 8 show other different embodiments in which a pair of pressing members are supported at the same fulcrum, and the portions corresponding to the above-mentioned embodiments are designated by the same reference numerals. The description is omitted.

In the embodiment shown in FIG. 7, scissors-shaped pressing members 33 and 34 intersecting each other are rotatably supported by a single support pin 35 in the direction of arrow G, and the pressing members 33, 34 are Engaging members 24, 25
A tension coil spring 26 is attached to each end 33a, 34a on the opposite side.

Even in this case, the same effect as that of the above-described embodiment can be obtained.

The embodiment of FIG. 8 is similar to the embodiment of FIG. 7 in that the pressing members 36 and 37 are crossed with each other and supported by the support pin 35 so as to be rotatable in the H direction shown by the arrow. An extension coil spring 26 is attached at a position a little distance from the intersection of 36 and 37 toward the engaging members 24, 25.

Even in this case, it is possible to obtain the same effects as the embodiments of FIGS. 1 to 6 and 7.

FIG. 9 shows an embodiment in which a compression coil spring is used as the urging member, and the portions corresponding to the respective embodiments of FIGS. 1 to 8 are designated by the same reference numerals, and the description thereof will be omitted.

In this embodiment, a pair of pressing members 41 and 42 formed in the same V-shape and having the same size are arranged at symmetrical positions with a space therebetween, and they are respectively rocked in the directions of the arrows by the support pins 43, 43. The movably supported engaging members 24 of the pressing members 41 and 42
A compression coil spring 44 is attached to each of the ends on the opposite side to 25 and 25.

Even in this case, the same operational effects as those of the above-described respective embodiments can be obtained.

As the urging member for urging the pressing member, a leaf spring, a rubber, an air spring or the like can be used in addition to the tension coil spring and the compression coil spring as described above.

As described above, according to the above-described embodiments, the pressing force of the pressing mechanism can be adjusted by changing the amount of protrusion of the engaging member from the side surface of the case. It is possible to easily make the pressing force on the side closer to the driving side of the roller different from the pressing force on the opposite side.

Further, unlike the above embodiments, a non-contact developing type image forming apparatus in which a developer carrying member (developing roller) is arranged to face a latent image carrying member (photosensitive drum) at a predetermined interval is provided. However, according to this invention, the relative positions of the developer bearing member and the latent image bearing member can be maintained in a uniform positional relationship at all positions along the axis.

[Effect of device]

As described above, according to the present invention, one biasing member interlocks a pair of pressing members to press an engaging member whose amount of protrusion can be adjusted to push the developer carrier to the latent image carrier side. Since it is pressed to, the relative positions of the developer carrying member and the latent image carrying member can be made to have a uniform positional relationship at all positions, and the pressing force can be easily adjusted only by changing the position of the engaging member. Therefore, when it is desired to adjust the pressing force, it is not necessary to change the biasing member to one having a different spring constant, which is convenient.

Further, since the developer bearing member is pressed by one urging member, even if the developer bearing member or the latent image bearing member is displaced or deformed due to some disturbance, it is against vibration. Since the guarantee is excellent, an appropriate pressing force can always be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing the vicinity of a developing unit of a laser printer as an image forming apparatus embodying the present invention, FIG. 2 is an overall configuration diagram showing the same laser printer as a whole, and FIG. 3 is a photosensitive drum of a developing roller. And FIG. 5 are perspective views and plan views for explaining a pressing mechanism that uniformly presses the developing roller against the photosensitive drum, and FIG. 6 is a case of the engaging member. FIG. 7 is a perspective view showing a mechanism for adjusting the amount of protrusion with respect to the side surface of each of FIGS. 7 and 8 is a view showing another embodiment in which a pair of pressing members are supported at the same fulcrum. FIG. 9 is a plan view similar to FIG. 9, FIG. 9 is a plan view similar to FIGS. 5, 7, and 8 showing an embodiment using a compression coil spring as a biasing member, and FIG. 10 is a conventional image forming apparatus. FIG. 3 is a schematic view illustrating the vicinity of a developing unit. 4 ... Photosensitive drum (latent image carrier) 7 ... Developing roller (developer carrier) 8 ... Developing unit, 18 ... Set screw 20 ... Pressing mechanism, 21 ... Case (support member) 21c ... … Side surface 22 …… Imaging unit case (holding member) 23 …… Supply roller, 24,25 …… Engagement member 26 …… Tension coil spring (biasing member) 27,28,33,34,36,37,41 , 42 ...... Pressing member 27a, 28a ...... Force point 31 ...... Guide rod 44 ...... Compression coil spring (biasing member) T ...... Toner (developer)

Claims (1)

(57) [Scope of utility model registration request] 1. A developing unit having a developer carrying member carrying a developer, and the electrostatic latent image carried on the surface to which the developer is adhered by the developer carrying member is visualized. An image forming apparatus, comprising: a latent image carrier, wherein the developing unit is held by a holding member so that the developing unit can be brought into contact with and separated from the latent image carrier, wherein the developer carrier of the developing unit is rotatable. On a side surface of the supporting member that supports the opposite side of the latent image carrier, a pair of engaging members that can adjust the protrusion amount with respect to the side surface are provided at intervals in the axial direction of the developer carrier. The holding member is provided with a pressing mechanism corresponding to the engaging member, the pressing mechanism interlocking a pair of pressing members by one urging member to bring the force points thereof into contact with the engaging members to press the engaging members. The pressing mechanism uniformly disperses the developer bearing member to the latent image bearing member side. An image forming apparatus characterized in that so as to press the.