JP3455018B2 - Image forming unit of image forming apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming unit of an image forming apparatus, and more particularly to an image forming unit having improved heat insulation from a fixing device.

[0002]

2. Description of the Related Art Image forming apparatuses such as copying machines and facsimiles have been downsized in recent years. To meet the demand for downsizing, a photoconductor, a developing device, In many cases, a charging device or the like is housed in a case to form an image forming unit, which contributes to downsizing of the image forming apparatus as a whole. With this configuration, the image forming photoreceptor, the developing unit,
The life of each part such as the cleaning blade, charging roller, toner recycling part, etc. can be made the same to make it more economical. Also, parts replacement is not performed at different times, but one unit is replaced collectively. There is an advantage that it can be handled only by itself.

When such an image forming unit is mounted in the main body of the image forming apparatus, the thermal fixing device is naturally located on the downstream side in the transfer sheet conveying direction, but it faces the thermal fixing device of the image forming unit. When the waste toner (recycled toner) collection means is located inside the wall, the case is made of plastic that easily conducts heat, so the heat from the heat fixing device easily causes the waste toner to be denatured and firmly fixed. , A means for blocking the heat transfer between them is necessary. In such a case, conventionally, a heat shield plate separately formed of a heat insulating material is arranged between the image forming unit and the heat fixing device to deal with the problem. However, using such a separate member means
Needless to say, problems such as an increase in parts and an increase in cost occur correspondingly, and a solution to this point has been desired.

Further, resource saving has become an important issue in recent years due to an increasing tendency to protect the environment, and it is necessary to design and manufacture the image forming unit and other components of the image forming apparatus so that they can be reused as much as possible. It has become to. However, the heat shield plate formed as a separate component as described above can hardly be recycled, and a solution to this problem is also desired.

Therefore, the present invention has been made in view of the above-mentioned conventional problems.
An object of the present invention is to provide an image forming unit of an image forming apparatus having a reusable structure that does not increase the number of parts and does not cause a particular increase in cost.

[0006]

In order to achieve the above-mentioned object, the image forming unit of the image forming apparatus of the present invention has a case in which a photoconductor, a developing device, a charging device and the like are integrated. In the image forming unit of the image forming apparatus housed inside, the outer wall portion of the case located on the thermal fixing device side on the downstream side in the transfer paper conveyance direction when mounted in the image forming apparatus main body has a gap as a double wall. Form and partition this void
It is characterized by forming a plurality of small chambers .

The invention according to claim 2 is characterized in that the upper part of the small chamber is opened.

A third aspect of the present invention is characterized in that an opening is provided at the bottom of the small chamber .

[0009]

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of an image forming unit of an image forming apparatus according to the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an appearance of an embodiment of an image forming unit of an image forming apparatus according to the present invention, and FIG. 2 is a diagram showing an image forming unit, a transfer / separation device, a fixing device, etc. according to the embodiment of the present invention. FIG. 3 is a cross-sectional view showing the arrangement, FIG. 3 is a perspective view showing the structure of the photosensitive member surrounding case of the image forming unit of FIG. 1, and FIG.

In these figures, 10 is an image forming unit, 11 is a transfer / separation device, and 12 is a fixing device. The image forming unit 10 is formed in a cartridge shape and is not shown in the main body of the image forming apparatus. It is removable.
The transfer / separation device 11 is provided with a transfer roller 13 and is rotatable in a vertical direction in the drawing by a rotation fulcrum 14.
The fixing device 12 includes a pressure roller 15 and a heating roller 16.

Further, the illustrated image forming unit 10 includes a photoconductor 1 in a case 17 (hereinafter referred to as a case) around the photoconductor.
8, charging roller 19 constituting the charging device, developing device 2
0, a cleaning device 21, and a toner recycling belt 22 for feeding the residual toner collected by the cleaning device 21 to the developing device 11, a toner conveying screw 42, an agent stirring member 43, and the like. In the figure, 37 is the case 17
An upper cover attached so as to cover the upper side prevents a person from coming into contact with the photoconductor 18, the charging roller 19, and the like.

An image forming operation using the image forming unit thus constructed will be briefly described. First, with the main body of the image forming apparatus mounted in a predetermined position, the photoconductor 18 can be rotated in the direction of the arrow in FIG. 2 by a drive source (not shown), and when the image forming operation starts, The surface of the surface is neutralized by irradiating static elimination light from a static elimination lamp (not shown), and the surface potential is averaged to a reference potential of 0 to -150 V, for example. Next, a high voltage is applied to the charging roller 19 which is in contact with the surface of the photoconductor 18 to charge the photoconductor 18, and the surface potential thereof is set to, for example, about -1100V. Then, by exposing the charged potential surface, the surface potential of an image becomes 0 to
-290V latent image portion is formed.

When this latent image portion moves to the position of the developing sleeve 23 of the developing device 20 due to the rotation of the photosensitive member 18, the latent image portion is held on the surface of the developing sleeve 23 which is biased, for example, about -800V. The formed toner adheres and the latent image portion is developed to form a toner image (visible image).

On the other hand, the transfer paper P fed from a paper feed unit (not shown) is moved by the registration roller pair 24 so that the front end of the transfer paper P and the front end of the toner image on the photoconductor 18 are aligned at the position of the transfer roller 13. The toner image on the photoconductor 18 is transferred to the transfer paper P by the transfer roller 13 with the timing adjusted. The transfer paper P is conveyed between the pressure roller 15 and the heating roller 16 of the fixing device 12, where the toner transferred by heat and pressure is fused to the transfer paper P, and is transferred to a discharge tray or the like (not shown) outside the machine. Discharge.

The residual toner remaining on the photoconductor 18 after the image transfer is scraped off by the cleaning blade 25 of the cleaning device 21, and it is assumed that almost no toner is attached and remains on the surface of the photoconductor 18 in the next image forming step. Move to. The residual toner collected by the cleaning device 21 is transferred to the developing device 20 by the toner recycling belt 22.
Of the agent stirring member 43.
And the toner is recycled by supplying it to the developing sleeve 23 again. In the figure, 41 is the cleaning blade 2.
5 holders.

By the way, the illustrated image forming unit 10 includes the outer wall portion 4 of the case 17 which is located on the downstream side in the transport direction of the transfer paper P.
The toner conveying screw 42 is located inside the toner container 4. There is residual toner scraped off by the cleaning blade 25 in this portion, and when heat from the heating roller 16 of the fixing device 12 is applied to this residual toner, the toner is denatured or adhered as described above. Therefore, the case 1 of the present embodiment
7, the outer wall portion 44 has a double wall structure as shown in the drawing, and a gap 47 is formed between the inner wall 45 on the toner conveying screw 42 side and the outer wall 46 exposed to the outside.
The air existing inside 7 blocks the heat from the fixing device 12, and the strength of the case 17 is enhanced by the double wall structure.

The void 47 is, as shown in FIGS.
It is divided into a plurality of small chambers 48 by a partition 49 connecting the inner wall 45 and the outer wall 46 to prevent heat transfer due to convection of the internal air, and the air heated by opening the upper part easily goes out of the small chamber 48. The heat is more difficult to be transferred to the inside of the case 17.

Although not shown, the inner wall 45 and the outer wall 4
It is also possible to provide holes or slits in the bottom portion 50 that connects the lower portions of 6 to facilitate the replacement of the air in the void 47 with the air outside the case 17 by convection.

[0021]

As described above, the image forming unit of the image forming apparatus according to the first aspect of the present invention is an image forming unit of the image forming apparatus in which the photoconductor, the developing device, the charging device, etc. are housed in a case. Since the outer wall of the case located on the heat fixing device side is formed as a double wall to form the void, there is an effect that the heat of the heat fixing device can be shielded without increasing the number of parts or increasing the cost. In addition, since it is not necessary to use a separate member for shielding heat, there is no member to be discarded for reuse, and there is an effect that efficient recycling becomes possible. Before
In addition to the effects described above, multiple small chambers are created by partitioning the void.
Therefore, it becomes difficult for the air in the void to convect inside.
Therefore, there is an effect that the heat insulating property is further improved.

In the image forming unit of the image forming apparatus according to the second aspect, since the upper portion of the small chamber is opened, in addition to the common effect described above , heated air is easily discharged from the small chamber having the upper portion opened. This has the effect of further improving the heat insulation.

The image forming unit of the image forming apparatus according to claim 3, is provided with the opening in the bottom of the chamber, in addition to the above common effect, air in the chamber having an opening on the bottom of the outer casing There is an effect that it is easier to be replaced by air and convection, and the heat insulating property is further improved.

[0024]

[Brief description of drawings]

FIG. 1 is a perspective view showing an appearance of an embodiment of an image forming unit of an image forming apparatus according to the present invention.

FIG. 2 is a cross-sectional view showing an arrangement of an image forming unit, a transfer / separation device, a fixing device and the like according to the embodiment of the present invention.

FIG. 3 is a perspective view showing a structure of a case around a photoconductor of the image forming unit of FIG.

FIG. 4 is a perspective view showing an external appearance by enlarging a main part of the image forming unit in FIG.

[Explanation of symbols]

10 Imaging unit 11 Transfer / separation device 12 Fixing device 13 Transfer roller 14 Rotation fulcrum 15 Pressure roller 16 heating roller 17 Photoconductor case 18 photoconductor 19 Charging roller 20 Developing device 21 Cleaning device 22 Toner recycling belt 23 Development sleeve 24 Pair of registration rollers 25 cleaning blade 26 Developer Stirring Section 37 Top cover 41 Cleaning blade holder 42 Toner transport screw 43 agent stirring member 44 outer wall 45 Inner wall 46 Outer wall 47 void 48 small rooms 49 partitions 50 Bottom of outer wall P transfer paper

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeru Watanabe 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Kenzo Tatsumi 1-3-6 Nakamagome, Ota-ku, Tokyo In stock company Ricoh (72) Inventor Takeo Suda 1-3-6 Nakamagome, Ota-ku, Tokyo Stock company Ricoh (72) Inventor Hiroshi Yoshinaga 1-3-6 Nakamagome, Tokyo Company Ricoh (72) Inventor Ken Amamiya 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh (72) Inventor Mayumi Ohori 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Company (56) References JP-A-6-236083 (JP, A) JP-A-63-313185 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 15/00 550 G03G 21/16-21/18 G03G 21/10-21/12 G03G 21/00 370-540

Claims (3)

(57) [Claims] 1. An image forming unit of an image forming apparatus comprising a photosensitive member, a developing device, a charging device, etc., which are housed in an integrated case, and when mounted in the main body of the image forming device, heat on the downstream side in the transfer paper conveyance direction. A space is formed by using the outer wall of the case located on the fixing device side as a double wall and partitioning the space into a plurality of small spaces.
An image forming unit for an image forming apparatus, which is characterized by forming a chamber . 2. The image forming unit of the image forming apparatus according to claim 1, wherein an upper portion of the small chamber is opened. 3. The image forming unit of the image forming apparatus according to claim 1, wherein an opening is provided at the bottom of the small chamber .