Patent Application
20210333740
An electrophotographic image forming apparatus forms an electrostatic latent image on the surface of a photoconductor by irradiating the photoconductor with modulated light corresponding to image information, supplies toner to develop the electrostatic latent image into a visible toner image, and transfers the toner image to a print medium to fix the toner image, thereby printing an image on the print medium.
The electrophotographic image forming apparatus may include a scanner for reading image information from a document, and the electrophotographic image forming apparatus including the scanner may be referred to as a multi-function printer.
Various examples will be described below with reference to the accompanying drawings, in which:
Hereinafter, examples of an image forming apparatus will be described with reference to the accompanying drawings. The same reference numerals are used to denote the same elements, and repeated descriptions thereof will not be given herein.
Referring to
As illustrated in
The developing device 220 accommodates the toner and supplies the toner to the electrostatic latent image formed on the photoconductor (i.e., the photosensitive drum 21) to develop the electrostatic latent image into the visible toner image. The developing device 220 may include the photosensitive drum 21, a charging roller 22, and a developing roller 23. As an example of a photoconductor on which the electrostatic latent image is formed, the photosensitive drum 21 may include a cylindrical metal pipe and a photoconductive layer formed on an outer periphery of the cylindrical metal pipe. The charging roller 22 is an example of a charger that charges a surface of the photosensitive drum 21 to a uniform electric potential. A charging bias voltage is applied to the charging roller 22. A corona charger (not shown) may be employed instead of the charging roller 22. The developing roller 23 supplies the toner accommodated in the developing device 220 to the electrostatic latent image formed on the surface of the photosensitive drum 21 to develop the electrostatic latent image. The described example employs a contact developing method in which the developing roller 23 and the photosensitive drum 21 come into contact with each other to form a developing nip. In this case, the developing roller 23 may include an elastic layer (not shown) formed on an outer periphery of a conductive metal core (not shown). When a developing bias voltage is applied to the developing roller 23, toner is moved and attached to the electrostatic latent image formed on the surface of the photosensitive drum 21 across the developing nip. When a non-contact method is employed, a surface of the developing roller 23 and the surface of the photosensitive drum 21 are spaced apart from each other by an interval of several hundred micrometers.
The developing device 220 may further be provided with a supply roller 24 for adhering toner to the developing roller 23. A supply bias voltage may be applied to the supply roller 24 to adhere toner to the developing roller 23. A regulating member 25 may regulate the amount of toner adhering to the surface of the developing roller 23. The regulating member 25 may be, for example, a regulating blade whose tip is brought into contact with the developing roller 23 at a certain pressure. A cleaning member 26 removes residual toner and foreign materials from the surface of the photosensitive drum 21 before charging. The cleaning member 26 may be, for example, a cleaning blade whose tip is in contact with the surface of the photosensitive drum 21. Hereinafter, the residual toner and foreign materials removed from the surface of the photosensitive drum 21 are referred to as waste toner.
The developing device 220 includes a toner accommodating portion 221 and a waste toner accommodating portion 222. The waste toner accommodating portion 222 accommodates waste toner removed from the surface of the photosensitive drum 21. In the example of
When a two-component developer using toner and a carrier is used as a developer, the toner accommodating portion 221 accommodates a magnetic carrier and toner. In this case, the developing roller 23 may include a rotatable sleeve and a magnet provided inside the sleeve. The carrier is attached to an outer periphery of the developing roller 23 by magnetic force of the magnet and the toner is adhered to the carrier by electrostatic force so that a magnetic brush formed of the carrier and toner is formed on the outer periphery of the developing roller 23. The toner is moved to the electrostatic latent image formed on the photosensitive drum 21 by a developing bias voltage applied to the developing roller 23. The regulating member 25 is located at a certain distance from the surface of the developing roller 23 to regulate a height of the magnetic brush formed on the outer periphery of the developing roller 23. The stirrer 27 stirs the carrier and toner to frictionally charge the toner while transferring the carrier and toner to the developing roller 23.
The exposure device 210 scans the surface of the photosensitive drum 21 charged with a uniform electric potential with light (L) modulated according to the image information. As the exposure device 210, for example, a laser scanning unit (LSU) may be employed, the LSU scanning the photosensitive drum 21 by deflecting light irradiated from a laser diode in a main scanning direction by using, for example, a polygon mirror.
The transfer device 230 may include a feed roller facing the surface of the photosensitive drum 21 to form a transfer nip. A transfer bias voltage for transferring the developed toner image on the surface of the photosensitive drum 21 onto the print medium P is applied to the feed roller. As the transfer device 230, a corona transfer device may be employed instead of the feed roller.
The toner image transferred to a surface of the print medium P by the transfer device 230 is maintained on the surface of the print medium P by electrostatic attraction. The fixing device 240 forms a permanent print image on the print medium P by applying heat and pressure to the toner image and fixing the toner image on the print medium P. The fixing device 240 may include, for example, a heater 241 and a pressing member 242 which are engaged with each other to form a fixing nip. The heater 241 may include a heating element 243 to heat the heater 241. Various types of devices may be employed as the heating element 243 depending on a structure of the fixing device 240. For example, a halogen lamp, a ceramic heater, or the like may be employed as the heating element 243.
An image forming process according to the above-described example will be briefly described. A charging bias voltage is applied to the charging roller 22, and the photosensitive drum 21 is charged to a uniform electric potential. The exposure device 210 scans the photosensitive drum 21 with modulated light corresponding to the image information to form an electrostatic latent image on the surface of the photosensitive drum 21. The toner is transferred by the stirrer 27 to the supply roller 24, and the supply roller 24 attaches the toner to the surface of the developing roller 23. The regulating member 25 forms a toner layer of a uniform thickness on the surface of the developing roller 23. A developing bias voltage is applied to the developing roller 23. The toner transferred to the developing nip as the developing roller 23 is rotated is moved towards and adhered to the electrostatic latent image formed on the surface of the photosensitive drum 21 by the developing bias voltage so that a visible toner image is formed on the surface of the photosensitive drum 21.
The print medium P drawn out from a feeding unit 250 by a pickup roller 251 is transported along the transport path PA. The print medium P is transported by a feed roller 252 to the transfer nip where the transfer device 230 and the photosensitive drum 21 face each other. When a transfer bias voltage is applied to the transfer device 230, the toner image is transferred to the print medium P by electrostatic attraction. The toner image transferred to the print medium P is fixed to the print medium P by receiving heat and pressure from the fixing device 240, whereby printing is completed. The print medium P is discharged by a discharge roller 253. The toner remaining on the surface of the photosensitive drum 21 without being transferred to the print medium P is removed by the cleaning member 26 and is accommodated in the waste toner accommodation portion 222.
The scanner 3 may include an image sensor 310 for reading image information from the document D conveyed along a document transport path DA. The image sensor 310 irradiates light onto the document D and receives light reflected from the document D. The image sensor 310 may include a photoelectric conversion element that photoelectrically converts received light and converts an optical signal into an electric signal. The image sensor 310 may include, for example, a contact image sensor (CIS), a charged-coupled device (CCD), or the like. The image sensor 310 may be a one-dimensional sensor extending in a main scanning direction, that is, in a width direction of the document D. In order to obtain two-dimensional image information, the document D is moved in a sub-scanning direction, that is, in a longitudinal direction. As another example, the document D may be located at a fixed position and the image sensor 310 may be moved in a sub-scanning direction. This type of scanner 3 is referred to as a flat-bed type scanner. The scanner 3 of the illustrated example is a bar-type scanner in which the image sensor 310 is located at a fixed position and the document D is moved in the sub-scanning direction. This type of scanner 3 may be implemented in a simpler structure and a smaller size as compared with the flat-bed type scanner.
A feed roller 320 forms a reading nip facing a contact window of the image sensor 310. The feed roller 320 may bring the document D in contact with a reading window of the image sensor 310. The feed roller 320 may transfer the document D while being pressed against the image sensor 310 and rotated. Although not shown in the drawings, a supply roller for guiding the document D to the reading nip may be on an upstream side of the reading nip, and a discharge roller for discharging the document D may be on a downstream side of the reading nip. Although not shown in the drawings, an automatic document feeder (ADF) for separating a plurality of documents D one by one and transferring them to the reading nip may be on the upstream side of the reading nip.
The image information read from the document D by the scanner 3 may be transmitted to the printing unit 2 and printed on the print medium P. The image forming apparatus 1 may include a line controller (not shown) that transmits the image information read from the document D using the scanner 3 through a communication device, such as a telephone line. The image information read from the document D using the scanner 3 may be transmitted to a host (not shown). With this configuration, it is possible to implement a multi-function printer having a printing function, a copying function, a facsimile function, and an image scanning function.
Referring to
The printing unit 2 for forming an image on the print medium P by an electrophotographic method is provided with the fixing device 240. The fixing device 240 fixes a toner image on the print medium P by heat and pressure as described above. An operating temperature of the fixing device 240 is, for example, about 160 to 200° C. The heat generated in the fixing device 240 may affect the scanner 3. For example, the image sensor 310 may deteriorate in performance when exposed to a high temperature. Therefore, an appropriate distance is required between the fixing device 240 and the scanner 3.
Referring to
The fixing device 240 is located on a downstream side of the C-shaped transport path PA, and therefore, is located close to the scanner 3 at the upper portion of the printing unit 2. The scanner 3 may be above the fixing device 240 and spaced upward from the fixing device 240 as shown by dashed lines 3-1 in
In order to reduce or minimize the footprint of the image forming apparatus 1, the scanner 3 may be located at the upper portion of the printing unit 2, and may be located in a vertical projected area X9 of the housing 4 with reference to a discharge direction A1 of the print medium P discharged from the printing unit 2. Furthermore, the scanner 3 may be located so as not to overlap with the heater 241 of the fixing device 240 in order to secure the appropriate distance between the fixing device 240 and the scanner 3. In an example, the scanner 3 is located to be spaced apart from the heater 241 of the fixing device 240 in the discharge direction A1.
In an example, the scanner 3 includes a first end 31 on the upstream side and a second end 32 on the downstream side with reference to the discharge direction A1 of the print medium P discharged from the printing unit 2. Both the first end 31 and the second end 32 of the scanner 3 are located in the vertical projected area X9 of the housing 4 with respect to the discharge direction A1. The first end 31 is located to be spaced apart from the heater 241 in the discharge direction A1. That is, the first end 31 is located on the downstream side of the heater 241 with respect to the discharge direction A1. When a vertical projected distance between the first end 31 and the heater 241 is X, 0≤X. The heater 241 may take various forms, where X is the vertical projected distance between the first end 31 and the center of the heater 241.
If X is less than 0, operation reliability of the scanner 3 may be degraded because the image sensor 310 may be affected by heat generated in the heater 241. According to an example, by arranging the scanner 3 to be spaced apart from the heater 241 in the discharge direction A1 of the print medium P so that 0≤X, an appropriate distance may be secured between the image sensor 310 and the heater 241 without increasing a dimension (e.g., the total height, the total length, etc.) of the image forming apparatus 1 and the scanner 3 may be stably operated without being affected by the heat of the fixing device 240. In addition, by arranging the scanner 3 in the vertical projected area X9 of the housing 4, it is possible to implement the image forming apparatus 1 incorporating the scanner 3 without increasing the footprint.
The scanner 3 may be installed on the upper cover 5 so as to be located in the vertical projected area X9 of the housing 4 and satisfy 0≤X with respect to the discharge direction A1 of the print medium P. In an example, the scanner 3 is integrated with the upper cover 5, which makes it possible to reduce the number of components of the image forming apparatus 1 and to reduce material cost, and also makes it possible to reduce manufacturing cost and manufacturing defect rate by simplifying a manufacturing process. In an example, the scanner 3 may be formed separate from the upper cover 5 and attached to the upper cover 5.
Referring to
Referring to
According to an example, the scanner 3 is installed in the upper cover 5 so as to be located in the vertical projected area X9 of the housing 4. In order to attach and detach the developing device 220, when the upper cover 5 is rotated, the scanner 3 is also rotated with the upper cover 5, and the opening 41 is opened. Therefore, user convenience in the process of attaching/detaching the developing cartridge 220 may be improved. Further, since the inside of the printing unit 2 is exposed to the outside by the operation of rotating the upper cover 5, a user may easily access the inside of the printing unit 2 to address a jam problem or the like.
Referring again to
In an example, a distance may be X≤100 mm. If X is greater than 100 mm, a length of the print medium P, which is discharged from the printing unit 2, guided by the lower surface 33 of the scanner 3 becomes excessively long and a jam may occur in the print medium P in the discharge process. There is also a possibility that the second end 32 of the scanner 3 is out of the vertical projected area X9 of the housing 4. The influence of the heat of the fixing device 240 on the scanner 3 and the possibility of jamming of the print medium P may be reduced under the condition of 0≤X≤100 mm. At the same time, it is easy to arrange the scanner 3 in the vertical projected area X9 of the housing 4 and the increase in the footprint of the image forming apparatus 1 may be reduced or prevented.
A structure in which the second end 32 of the scanner 3 is located inside an end 52 of the loading table 51 in the discharge direction A1 may be easily secured under the condition of X≤100 mm. With this configuration, an area between the second end 32 of the scanner 3 and the end 52 of the loading table 51 in an upper area of the loading table 51 is open, and thus, a user may easily access the print medium P loaded on the loading table 51.
A structure in which the scanner 3 is located at approximately the center of the vertical projected area X9 of the housing 4 may be realized under the condition of 0≤X≤100 mm. The scanner 3 may be operated in the vertical projected area X9 of the housing 4, and a use space of the image forming apparatus 1 may be reduced or minimized.
The lower surface 33 of the scanner 3 partially faces the loading table 51 under the condition of 0≤X≤100 mm. Therefore, when moisture in the print medium P is evaporated by heat received from the fixing device 240 in a fixing process, water vapor is covered by the scanner 3 and is not visible from the outside. Thus, the problem of mistaking the water vapor as smoke, such as smoke caused by ignition, may be reduced or prevented.
The lower surface 33 of the scanner 3 may be provided with a structure for reducing contact resistance with the print medium P. As an example, a plurality of guide ribs 34 protruding downward toward the loading table 51 and extending in the discharge direction A1 of the print medium P to guide the print medium P may be formed on the lower surface 33 of the scanner 3. The plurality of guide ribs 34 may be arranged in a width direction of the print medium P. The print medium P may be guided by the guide ribs 34 and stably discharged from the printing unit 2 to the loading table 51. Even when a curl or the like is generated on the print medium P and the print medium P is curved upward and discharged as indicated by C1 in
The moisture in the print medium P may be evaporated by the heat received from the fixing device 240 in the fixing process. The evaporated moisture may be condensed and attach to the lower surface 33 of the scanner 3 or the guide ribs 34 and then attach to the print medium P to contaminate the print medium P.
Referring to
With this configuration, water vapor evaporated from the discharged print medium P is drawn into the condensation chamber 35 through the communication hole 36. The water vapor condenses in the condensation chamber 35. Therefore, contamination of the print medium P by the condensed water may be reduced or prevented. Further, since the water vapor is drawn into the condensation chamber 35, visibility of the water vapor is reduced. Thus, the problem of mistaking the water vapor as smoke caused by ignition may be reduced or prevented.
Referring to
The inlet guide 37 may be located in the vertical projected area of the housing 4. That is, the installation angle and length of the inlet guide 37 may be determined such that the inlet guide 37 is entirely located in the vertical projected area of the housing 4. With this configuration, an increase in the footprint of the image forming apparatus 1 may be reduced or prevented.
The image forming apparatus 1 may include a discharge guide 38 for guiding the document D discharged from the scanner 3 after being scanned. The scanned document D may be loaded on the discharge guide 38. By using the discharge guide 38, it is possible to prevent the document D from falling onto the loading table 51 and mixing with the print medium P.
The discharge guide 38 may be located in the vertical projected area of the housing 4. That is, the installation angle and length of the discharge guide 38 may be determined such that the discharge guide 38 is entirely located in the vertical projected area of the housing 4. With this configuration, an increase in the footprint of the image forming apparatus 1 may be reduced or prevented.
In the above examples, it has been described that the scanner 3, the inlet guide 37, and the discharge guide 38 are located in the vertical projected area of the housing 4. The vertical projected area of the housing 4 may be substantially the same as the vertical projected area of the printing unit 2 since the housing 4 has the minimum size in which the printing unit 2 is accommodated.
A transfer direction of the document D is the same as the discharge direction A1 of the print medium P in the above-described examples but may be opposite to the discharge direction A1 of the print medium P. In the example of
It should be understood that the present disclosure described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each example should typically be considered as available for other similar features or aspects in other examples. Therefore, the scope of the present disclosure is defined not by the description of the present disclosure but by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2019-0006104 | Jan 2019 | KR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2019/055586 | 10/10/2019 | WO | 00 |
