JPH0830912B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus such as a laser beam printer or an electrophotographic copying machine, and more particularly to a small-sized image forming apparatus.

[Conventional technology]

Conventionally, for example, a laser beam printer used as an output device of an information processing system is configured as shown in FIG.

That is, in the figure, 1 is a main body of the apparatus, 2 is a process cartridge detachably mounted in the main body 1, and a photosensitive drum 3 as an image carrier is provided in the cartridge 2.
In addition, well-known process equipment such as a charger 4, a developing device 5, a cleaner 6 and the like arranged around it are built in. 7 is a scanner unit that emits and scans a laser beam,
By irradiating the photosensitive drum 3 uniformly charged by the charger 4 with the radar light L emitted from the unit 7 through the mirror 8, a latent image corresponding to desired print (image) information is formed, The latent image is developed by the developing device 5.

Reference numeral 9 is a cassette for accommodating a sheet material S such as transfer paper, 10 is a feeding roller for feeding one sheet material S from the cassette 9, and the sheet material S fed by the roller 10 is a photosensitive drum by a registration roller 11. It is conveyed toward the drum 3 in synchronization with the rotation of the drum 3. 12 is the developing device 5
Is a transfer charger for transferring the developed image formed on the photosensitive drum 3 onto the sheet material, and 13 is a conveyor belt unit for guiding the sheet material S on which the image is transferred by the charger 12 to the fixing device 14.

In the above configuration, when a print start command is input from a computer, an image reader, or the like (not shown), the printing (image forming) operation is started, and the sheet material S in the cassette 9 is started.
Is conveyed by the feeding roller 10 and the registration roller 11 so as to traverse the inside of the apparatus main body from the right side to the left side in the figure, and passes between the photosensitive drum 3 and the transfer charging device 12 and the fixing device 14 so that the known electronic It is printed according to the photographic process and is discharged to the outside of the device.

The apparatus of the illustrated example is provided with two types of discharging methods. When discharging the sheet face up, that is, with the printing surface facing upward, the discharging roller for face up is used.
When the sheet is discharged from 15a to the discharge tray 16a and is discharged face down, that is, with the print side facing down, to the page side, the sheet material conveying direction switching mechanism such as a flapper and the sheet omitted from the above face-up discharge roller 15a The sheet is guided upward through a material guide member or the like and discharged from the face-down discharge roller 15b to the discharge tray 16b. These sheet material discharging methods are arbitrarily selected by the operator and designated by a computer or the like.

Further, when performing maintenance of the apparatus, that is, jam processing, cartridge replacement, etc., the upper portion 1a of the apparatus main body 1 is rotated upward with respect to the lower portion 1b about the support shaft P as shown by the chain line in FIG. Is opened and the hand is inserted from the direction of the arrow A in the figure to perform the work.

[Problems to be solved by the invention]

However, the above-mentioned conventional example has some drawbacks in the internal structure and the like as follows.

That is, since the sheet material is conveyed laterally in the apparatus main body over the entire length as described above, conveying members such as rollers are arranged in the entire apparatus, and although not shown, a transmission mechanism such as a gear for driving these conveying members. Belts and belts must also be placed throughout the device. Therefore, the number of parts is increased and the cost is increased, the space for disposing the transmission mechanism is increased, and the driving torque is increased. Therefore, there are problems such as an increase in the size of the motor and the like and an increase in noise and power consumption. It was

In addition, since the sheet material conveying path is formed over the entire device, the cross-sectional space inside the device is divided, and electric components such as the electric circuit board and the power supply must be stored separately in the empty space. Limited storage efficiency due to limited space. Further, when the above electric parts are not divided and are concentratedly housed in the lateral side surface and the bottom of the device, the whole device becomes large, and there is a disadvantage that a useless space is generated inside.

Further, since the cassette for accommodating the sheet material is projected from the main body of the apparatus, there is a problem that the occupied area becomes large even when the apparatus is miniaturized during use. Further, when carrying out jam processing or cartridge replacement, the sheet material conveying path is constructed so as to traverse the entire apparatus, so the entire apparatus must be divided into two large sections and opened as shown by the chain line in FIG. did not become. In addition, since the sheet material conveying system is arranged on the lower side of the cartridge and the optical system is arranged on the upper side in the structure of the apparatus, it is necessary to move an optical system requiring particularly precise positional accuracy, for example, a mirror etc. It becomes a technical problem. In particular, if the rigidity of the main body of the apparatus is insufficient, the printing condition and printing accuracy will deteriorate due to distortion and vibration of the optical system. Therefore, especially on the rotating side, sufficient rigidity is required to maintain the position and accuracy of the parts, which not only increases the weight and deteriorates the operability, but also causes a problem that the manufacturing cost increases.

An object of the present invention is to solve the above problems of the conventional example.

B. Structure of the Invention [Means for Solving the Problems] The present invention relates to an image forming apparatus for forming an image on a sheet material, in which the image forming process on the sheet material is performed in a vertical direction and in a straight line. The sheet material for double-sided image formation which is carried out in the sheet material conveyance path and is extended in the vertical direction to guide the sheet material from the downstream side of the sheet material conveyance path to the upstream side of the sheet material conveyance path again. It is characterized in that a transport path is provided.

[Action]

With the above configuration, the sheet material conveying member and the driving means thereof can be arranged centrally on the front side inside the apparatus, and the sheet material can be efficiently conveyed with a small number of parts. Further, since the sheet material conveying path does not divide the space in the apparatus, the internal space can be used without waste in the arrangement of electrical components and the like. Further, the cassette for accommodating the sheet material can be mounted on the top or bottom of the device, and the protrusion from the device body is reduced, so that the area occupied by the installation can be reduced. Further, at the time of maintenance of the apparatus, it is possible to open the sheet material conveyance path by configuring at least a part of the sheet material conveyance path located on the front side of the apparatus so as to be able to rotate forward. . In this case, since the optical component is fixed to the apparatus main body side, the positional accuracy and stability of the optical component are excellent.

〔Example〕

FIG. 1 is a cross-sectional view of a laser beam printer as an image forming apparatus showing an embodiment of the present invention. Members having the same functions as those in FIG. 3 are designated by the same reference numerals and their repeated description is omitted. To do.

First, the internal configuration of the apparatus will be described according to the sheet material conveyance path. The cassette 9 for accommodating the sheet material S is arranged on the upper part of the apparatus main body 1, and is directed toward the front surface (front surface) side of the main body 1, that is, the right side surface side in the drawing by the sheet feeding roller 10.
Are sent out one by one from the top. The feeding cassette 9
The sheet material S sent out from the sheet is sent between the photosensitive drum 3 and the transfer charger 12 through the feed guide member 17 and the registration roller 11 which are curved downward, and the sheet material S is well known in the same manner as in the conventional example. After the image is transferred according to the process, the conveying belt unit 13 guides the image to the fixing device 14 to form an image on the sheet material. The above registration rollers
The conveying path of the sheet material S from 11 to the fixing device 14 is configured to be substantially vertical in the up-down direction while being slightly inclined in the front-rear direction.

The sheet material S that has passed through the fixing device 14 is conveyed by the conveying roller 18
After being guided to the discharge guide member 19 which is curved in the opposite direction to the feed guide member 17, by the flapper 36 in the case of one-sided printing, the flapper 20 guides the face-up discharge roller 15a to the same discharge tray. 16a or from the face-down discharge roller 15b to the discharge tray 16b.
Selectively discharged on.

In the illustrated example, the sheet material discharging directions of the face-up discharging tray 16a and the discharging roller 15a are arranged in a direction opposite to the direction in which the sheet material passes through the fixing device 14 and are substantially parallel to each other. The sheet discharging direction of the sheet discharging tray 16b and the discharging roller 15b is configured so as to be slightly upward in a direction substantially perpendicular to the direction in which the sheet material passes through the fixing device 14.

In the illustrated example, one common tray is selectively arranged between the face-up discharge tray mounting position 16a shown by the solid line in FIG. 1 and the face-down discharge tray mounting position 16b shown by the chain line in FIG. The flapper 20 is automatically switched according to the arrangement position.

That is, when the discharge tray is located on the face-up side 16a, the flapper 20 is at the position indicated by the solid line, and the sheet material S that has passed through the fixing device 14 passes through the guide member 19 and the face-up discharge roller 15a, and then moves about. The direction is changed by 180 °, and the sheet is discharged onto the discharge tray 16a with the image surface (print surface) facing upward. When the discharge tray is located on the face-down side 16b, the flapper 20 is at the position indicated by the chain line in the figure,
The guide member 19 and the face-down discharge roller 15b change the conveying direction by about 90 °, and the sheets are stacked on the face-down discharge tray 16b with the image surface facing downward in page order.

The face-up discharge tray 16a and the face-down discharge tray 16b may be provided separately,
Further, the flapper 20 may be configured so that the operator can switch it arbitrarily.

As described above, the sheet material conveying path is formed in a substantially vertical direction on the front side of the apparatus body, and the sheet material conveying member and the transmission mechanism such as a gear for transmitting power to the sheet material conveying member are centrally arranged in this portion. be able to. Therefore, the space used in the apparatus body is small, and the number of parts can be reduced. In addition, the number of parts can be reduced and the torque can be reduced as compared with the case where many gears and chains are used due to the concentrated arrangement, and the noise can be reduced.

Further, by shortening and concentrating the sheet material conveying path, it is possible to form a collective space K in the portion surrounded by the chain line in FIG. 1 inside the apparatus, so that electrical components such as an electric circuit board and a power source can be efficiently accommodated. It becomes possible to downsize the entire device. Even when it is necessary to provide a shield so that the noise generated from these electrical components is not radiated to the outside of the device, the electrical components are concentrated inside the device, so the shielding is easy and the cost is low. It is possible to prevent the generation of radiation noise efficiently.

Further, since the sheet material accommodating cassette 9 is arranged in the upper part of the device, the cassette 9 does not extend to the front of the device in the installed state and the occupied area on the desk does not increase. To attach and detach the cassette 9, in this example, a lever (not shown) or the like is provided on the front upper part, and by operating this lever, the cassette 9 becomes a state shown by a chain line, and from this state, the operator moves the cassette 9 in the arrow direction. The drawer can be replaced or the sheet material can be replenished. After that, the cassette 9 is reinserted and pushed down from above so that the cassette 9
Is in the normal printing state and can be fed. Therefore, all the cassettes can be attached and detached on the front side of the device.

Further, the sheet material fed from the cassette 9 is immediately turned downward by the guide member 17 in the clockwise direction to enter the vertical transport section, that is, the printing section (image forming section), and the sheet material is guided after the printing is completed. It is discharged by changing the traveling direction counterclockwise by 19. In general, since the sheet material is curled in the conveying path in accordance with the curving direction of the conveying path, conventionally, a curl removing roller or the like was provided in the conveying path. As described above, since the two curved portions 17 and 19 are formed on the upper side and the lower side of the vertical transport unit and the curving directions are opposite, as a result, the sheet material discharged onto the tray 16a or 16b. Has little curl, and not only the handling property of the sheet material is good, but also the stacking property is good.

Reference numeral 30 denotes a sheet material re-conveying path that reverses the sheet material having one side printed to guide printing to both sides of the sheet material and guides the sheet material to the upstream side of the registration roller again.

The sheet material re-conveying path 30 includes sheet material conveying rollers 31 and
32 and guide members 33 to 35 and the like. A flapper 36 guides the sheet material to the re-conveyance path 30.

When printing on both sides of the sheet material, single-sided printing is performed with the flapper 36 in the solid line position and the flapper 20 in the solid line position or the chain line position, and the discharge roller 15a is printed.
Alternatively, it is once conveyed by 15b toward the discharge tray 16a or 16b. When the trailing edge of the sheet material passes through the flapper 36, the flapper 36 moves to the position indicated by the chain line in the figure, and the discharge rollers 15a or 15b reversely rotate so that the sheet material enters the re-conveying path 30 and the conveying rollers 31 and 32 are conveyed. Is guided to the registration roller 11 by the rotation. After that, printing is performed on the back side by the same process as in the case of single-sided printing described above, the flapper 36 returns to the chain line position, and is ejected to the ejection tray 16a or 16b by the ejection roller 15a or 15b via the flapper 20.

Also in the present embodiment, most of the sheet material conveying paths including the sheet material re-conveying path 30 are concentratedly arranged on the front side of the apparatus, so that the number of parts of the conveying member and the drive transmission member is small and efficient conveyance is possible. It is possible. Further, since the space K for accommodating electrical components and the like is formed without being divided in the device, it can be used without waste.

Further, in the present embodiment, the re-conveying path 30 for double-sided printing is provided between the printing section for the sheet material and the sheet discharging section in the image forming apparatus capable of printing only one side as shown in FIG. When developing from the single-sided printing device shown in FIG. 2 to the double-sided printing device of this example, in order to provide a re-conveying path for double-sided printing at the bottom of the device as in the conventional device, the base part which is structurally basic is modified. Compared with the above, there is little influence on other parts, and only the front part of the device needs to be modified. Further, in the case of connecting a sorter (not shown) as an option, there is also an advantage that the same sorter can be attached because the paper discharge positions (height) are the same in both devices.

C. Effects of the Invention As described above, the present invention has the following effects.

Since the sheet material conveying path is concentrated, the number of parts for sheet material conveying parts such as rollers and rollers and transmission parts such as gears for transmitting rotational force to these parts is reduced, and the driving torque and noise are small, and the sheet is efficiently transferred. Material can be transported.

Since the sheet material conveying path is on the front side of the apparatus and is not arranged in the entire apparatus unlike the above-described conventional example, a wide space that is not divided can be formed inside the apparatus. Therefore, this space can be used without waste for housing electrical components.

It is possible to dispose the sheet material feeding cassette at the top or bottom of the apparatus body and discharge the sheet material to the front of the apparatus. Therefore, there is no protrusion of the cassette in front of the device, the area occupied by the device installation is small, and the device looks small visually. Further, since the sheet material is discharged in front of the device, it is easy to take out.

Forming sheet material conveying paths that are curved in opposite directions on the upstream side and the downstream side of the sheet material conveying path in the image forming unit for the sheet material so that the curling directions of the sheet materials are opposite to each other and cancel each other. It is also possible to reduce the curl of the sheet material output by and improve the handleability.

Since the sheet material conveying paths are concentrated on the front side of the apparatus, the sheet material conveying section is very compact. Therefore, at the time of maintenance such as jam processing and cartridge replacement, it is easy to move the sheet material conveying portion toward the front of the apparatus to open the sheet material conveying path greatly. Further, in that case, the optical parts such as lasers and mirrors, which are particularly required to have positional accuracy and mounting stability, are configured so as not to move during maintenance of the above-mentioned device, thereby facilitating the mounting of those parts and improving the accuracy. It can be installed well.

[Brief description of drawings]

FIG. 1 is a sectional view of a laser beam printer as an image forming apparatus showing a first embodiment of the present invention, and FIG. 2 shows an image forming apparatus capable of only single-sided printing without a re-conveyance path for double-sided printing. A sectional view and FIG. 3 are sectional views of a conventional laser beam printer. 1 is an apparatus main body, 2 is a process cartridge, 9 is a sheet material accommodating cassette, 10 is a feeding roller, 11 is a registration roller, 12 is a transfer charger, 13 is a sheet material conveying belt unit, 14 is a fixing device, and 15a and 15b. Is a discharge roller, and 16a and 16b are discharge trays.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Ishii 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Tsuyoshi Waratani 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Incorporated (56) Reference JP-A-49-18329 (JP, A) JP-A-63-15262 (JP, A) JP-A-63-301057 (JP, A)

Claims (4)

[Claims] 1. An image forming apparatus for forming an image on a sheet material, wherein an image forming process on the sheet material is carried out in a sheet material conveying path in which the sheet material is vertically and linearly conveyed. An image forming apparatus comprising: a re-conveyance path for double-sided image formation, which extends in the vertical direction and guides a sheet material from the downstream side of the material conveyance path toward the upstream side of the sheet material conveyance path. 2. The sheet conveying path and the re-conveying path for double-sided image formation are arranged between the image forming process means and a side surface of the apparatus main body. Image forming device. 3. A sheet material conveying path which is curved in an upstream side and a downstream side in a sheet material conveying direction of a sheet material conveying path in which the sheet material is vertically and linearly conveyed, and the curved sheet. The image forming apparatus according to claim 1, wherein the material conveying paths are curved in opposite directions. 4. The image forming apparatus according to claim 1, wherein the sheet material feeding means and the sheet material storing means are provided at the top or bottom of the apparatus main body.