Abstract:
Provided is a high-voltage power supply including a board having at least one bent portion separating a first region of the board from a second region of the board, the first region not being coplanar with the second region of the board; a first circuit, on the first region of the board, generating a second voltage according to a first voltage; and a second circuit, on the second region of the board, amplifying the second voltage and then rectifying the amplified second voltage.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Patent Application No. 2008-72444, filed Jul. 24, 2008, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Aspects of the present general inventive concept relate to a power supply and more particularly, to a high-voltage power supply which generates a high-voltage signal by using a low-voltage signal. 
     2. Description of the Related Art 
     An image forming apparatus, such as a laser beam printer (LBP), includes a plurality of devices that electronically operate. Examples of the plurality of devices included in the image forming apparatus include a device for charging a surface of a photoconductive drum, a device for forming an electrostatic latent image on the surface of the photoconductive drum, and a device for transferring the electrostatic latent image onto a printing medium. Power sources for each of the plurality of devices may be different, and are a direct current (DC) high-voltage signal, such as DC 1000 V, equal to or above a predetermined voltage. However, an alternating current (AC) voltage, such as a home AC voltage of 220 Vrms (Volts root mean square) is supplied to the image forming apparatus after being converted to a predetermined DC low-voltage signal, such as DC 5 V, and thus the image forming apparatus includes a high-voltage power supply that generates a plurality of high-voltage signals by receiving a low-voltage signal. 
     Such a high-voltage power supply is one flat board including a circuit for generating a plurality of high-voltage signals by receiving one low-voltage signal. Here, contacts in the board, specifically, contacts grounded to a contact to which a high-voltage signal is applied, should be spaced apart from each other so as to prevent a spark between the contacts. Accordingly, it is difficult to reduce the size of the board, and thus difficult to apply a conventional high-voltage power supply to small home appliances. The number of circuits arranged on the board of the high-voltage power supply increases as the number of high-voltage signals generated by using one low-voltage signal increases. 
     SUMMARY OF THE INVENTION 
     Aspects of the present general inventive concept provide a high-voltage power supply having a small size, and an electronic device, such as an image forming apparatus, including the high-voltage power supply. 
     According to an aspect of the present general inventive concept, there is provided a high-voltage power supply including: a board having at least one bent portion separating a first region of the board from a second region of the board, the first region not being coplanar with the second region of the board; a first circuit, on the first region of the board, generating a second voltage according to a first voltage; and a second circuit, on the second region of the board, amplifying the second voltage and then rectifying the amplified second voltage. 
     According to another aspect of the present general inventive concept, there is provided an image forming apparatus including: a charging unit uniformly charging a surface of a photoconductive drum; a light exposing unit performing light exposure on the surface of the photoconductive drum to form an electrostatic latent image; a developing unit developing the electrostatic latent image using a developer; a transferring unit transferring the developed electrostatic latent image onto a printing medium; a fusing unit fusing the transferred developed electrostatic latent image onto the printing medium; a cleaning unit removing the developer remaining on the photoconductive drum; and a high-voltage power supply supplying power to the charging unit, the light exposing unit, the developing unit, the transferring unit, the fusing unit, and the cleaning unit, wherein the high-voltage power supply includes: a board having at least one bent portion separating a first region of the board from a second region of the board, the first region not being coplanar with the second region of the board; a first circuit, on the first region of the board, generating a second voltage according to a first voltage; and a second circuit, on the second region of the board, amplifying the second voltage and then rectifying the amplified second voltage. 
     According to another aspect of the present general inventive concept, there is provided an electronic device including: electronic components receiving power; and a high-voltage power supply supplying power, wherein the high-voltage power supply includes: board having at least one bent portion separating a first region of the board from a second region of the board, the first region not being coplanar with the second region of the board; a first circuit, on the first region, generating a second voltage according to a first voltage; and a second circuit, on the second region, amplifying the second voltage and then rectifying the amplified second voltage. 
     Additional aspects and/or advantages of the present general inventive concept will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the general inventive concept. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects and advantages of the general inventive concept will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a block diagram illustrating an image forming apparatus including a high-voltage power supply, according to an embodiment of the present general inventive concept; 
         FIG. 2  is a block diagram illustrating a high-voltage power supply according to an embodiment of the present general inventive concept; 
         FIG. 3  is a diagram for describing a high-voltage power supply according to an embodiment of the present general inventive concept; 
         FIG. 4  is a schematic diagram for describing a high-voltage power supply according to another embodiment of the present general inventive concept; and 
         FIG. 5  is a schematic diagram for describing a high-voltage power supply according to another embodiment of the present general inventive concept. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail to the present embodiments of the present general inventive concept, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present general inventive concept by referring to the figures. 
       FIG. 1  is a block diagram illustrating an image forming apparatus including a high-voltage power supply, according to an embodiment of the present general inventive concept. Referring to  FIG. 1 , the image forming apparatus includes a charging unit  110 , a light exposing unit  120 , a developing unit  130 , a transferring unit  140 , a fusing unit  150 , and a cleaning unit  160 . 
     Here, the image forming apparatus denotes a device having a printing function, such as a multi-function peripheral (MFP) having a printing function. A one-color laser beam printer and a color laser beam printer are examples of such an image forming apparatus. 
     The charging unit  110  uniformly charges the entire surface of a photoconductive drum (not shown) included in the image forming apparatus with a uniform polarity. 
     Then, the light exposing unit  120  performs light exposure on the surface of the photoconductive drum considering printing data received through an input terminal IN 1  of the light exposing unit  120 , thereby forming an electrostatic latent image corresponding to the printing data on the surface of the photoconductive drum. Here, the electrostatic latent image has a uniform polarity, such as “+”. 
     The developing unit  130  generates a developed image by developing the electrostatic latent image formed on the surface of the photoconductive drum by using a developer, such as toner. Here, the developer has a uniform polarity, such as “−”. 
     The transferring unit  140  transfers the developed electrostatic latent image formed on the surface of the photoconductive drum by the developing unit  130  onto a printing medium. Here, the printing medium denotes a medium on which the developed image is to be printed, and a material of the printing medium may vary, such as a paper or an overhead projector (OHP) film. 
     The fusing unit  150  fuses the developed electrostatic latent image transferred onto the printing medium by the transferring unit  140  onto the printing medium. In detail, the fusing unit  150  fuses the developed electrostatic latent image onto the printing medium by using heat and pressure. 
     The cleaning unit  160  starts to operate after the operation of the fusing unit  150  is completed, and removes the developer left on the surface of the photoconductive drum. All of the developer on the surface of the photoconductive drum should be transferred to the printing medium, but in reality, some developer may be left on the surface of the photoconductive drum after a transferring operation. The developer left on the surface of the photoconductive drum, after the operation of the transferring unit  140  is completed, with respect to an nth piece of printing data (wherein n is a natural number) received through the input terminal IN 1  may deteriorate the printing quality of printed matter of an n+1th piece of printing data, and thus may be completely removed by the cleaning unit  160  before the light exposing unit  120  starts to operate for the n+1th piece of printing data. 
     Each of the charging unit  110 , the light exposing unit  120 , the developing unit  130 , the transferring unit  140 , the fusing unit  150 , and the cleaning unit  160  electronically operates by receiving power from a power source. Here, the power source applied to each of the charging unit  110 , the light exposing unit  120 , the developing unit  130 , the transferring unit  140 , the fusing unit  150 , and the cleaning unit  160  may be different and a direct current (DC) high-voltage signal equal to or above a uniform voltage, such as a DC 1000 V. However, an alternating current (AC) voltage, such as a home AC voltage of 220 Vrms, is converted to a predetermined DC low-voltage signal, such as DC 5 V, and supplied to the image forming apparatus. Accordingly, the image forming apparatus includes a high-voltage power supply that generates a plurality of high-voltage signals by receiving a low-voltage signal. Additionally, a high-voltage power supply may be used to supply power to other electronic devices having electronic components using DC high-voltage power signals, such as computers, telecommunications devices, radio transmission devices, televisions, electronic visual displays, home electronic appliances and other such electronic devices. A high-voltage power supply according to several embodiments of the present general inventive concept will now be described. 
       FIG. 2  is a block diagram illustrating a high-voltage power supply according to an embodiment of the present general inventive concept. The high-voltage power supply includes a first circuit  210  and a second circuit  250 . The first circuit  210  includes a low-voltage input unit  220  and a controller  230 , and the second circuit  250  includes a high-voltage generator  260  and a high-voltage output unit  270 . 
     The low-voltage input unit  220  receives a first voltage. The controller  230  generates a second voltage according to the received first voltage. Here, the first voltage denotes the DC low-voltage signal transmitted to the image forming apparatus, such as DC 5 V, and the second voltage denotes the AC low-voltage determined according to the first voltage, such as DC 18 Vrms. Here, a relationship between the first and second voltages is predetermined. For this, the controller  230  may include an oscillating circuit. 
     The high-voltage generator  260  amplifies the second voltage with a predetermined gain, and rectifies the amplified second voltage. Here, the rectified second voltage is a DC high-voltage signal, i.e., a DC voltage equal to or above a predetermined voltage, such as 800 V. Since the rectified second voltage may include an alternating component (vibration), the high-voltage generator  260  may include an electrolyte condenser that flattens the rectified second voltage. However in the following embodiments, it is assumed that the high-voltage generator  260  does not include the electrolyte condenser for convenience of description. 
     Meanwhile, the high-voltage generator  260  may amplify the second voltage with a plurality of different gains, and generate a plurality of DC high-voltages by rectifying the amplified second voltage with different gains. The plurality of DC high-voltage signals may be power sources for each of devices that electronically operate in an image forming apparatus. For example, the high-voltage generator  260  may amplify the second voltage, such as 18 Vrms, with a plurality of different gains, and generate a DC high-voltage signal of −300 V, a DC high-voltage signal of −1200 V, and a DC high-voltage signal of +1300 V by rectifying the amplified second voltages with different gains. Then, the DC high-voltage signal of −1200 V may be supplied to the charging unit  110  of  FIG. 1  as the power source of the charging unit  110 , the DC high-voltage signal of −300 V may be supplied to the developing unit  130  of  FIG. 1  as the power source of the developing unit  130 , and the DC high-voltage signal of +1300 V may be supplied to the transferring unit  140  of  FIG. 1  as the power source of the transferring unit  140 . 
     The high-voltage output unit  270  outputs the plurality of high-voltage signals generated by the high-voltage generator  260  via a plurality of output terminals. 
     The first circuit  210  is on a first region (not shown) of a board that has a bent region and the second circuit  250  on a second region (not shown) of the board. According to aspects of the present general inventive concept, a board having a bent region may denote one board having at least one curved or bent region, a plurality of plane boards or regions that are one plane board by connecting at least one part of the plane boards or regions to each other so that one end of a plane board or region is connected to another end of another plane board or region at a predetermined angle, or combinations thereof. The latter boards are used for convenience of description. The plurality of planes or regions may be electrically connected. 
     The board having a bent region, for example, a board having a double open sided box shape, may include a plurality of planes or regions, such as a first rectangular plane or region having an area A, a second rectangular plane or region having an area  2 A and connected to the first plane or region, and a third rectangular plane or region having an area A and connected to the second plane or region, wherein A is a positive number. Here, an area of the board on which the second circuit  250  is disposed, for example, an area of the second plane or the second region, may be larger than an area of the board on which the first circuit  210  is disposed, such as an area of the first plane or the first region. However, an arrangement of the first and second circuits  210  and  250  on the board is not limited thereto, and may vary. While not required, a further circuit can be disposed on the third region or the third plane. 
     The first and second circuits  210  and  250  may be one module, for example, in one integrated chip. 
     Also, at least one region of the board may be covered with an insulator. In detail, at least one part of the board, the first circuit  210 , and the second circuit  250  may be prepared in a case, and a space in the case excluding the board, the first circuit  210 , and the second circuit  250  may be filled with the insulator. 
       FIG. 3  is a schematic diagram for describing a high-voltage power supply according to an embodiment of the present general inventive concept. For convenience of description, it is assumed that a board  310  has a box shape, and a first circuit and a second circuit are on a first region  311  and a second region  312  of the board  310 , respectively. The first region  311  and the second region  312  are separated by a bent region  313 . 
     According to the current embodiment, the high-voltage power supply does not include an insulator, and the board  310  includes a low-voltage input unit  320 , a controller  322 , a high-voltage generator  328 , and a high-voltage output unit  330 . 
       FIG. 4  is a schematic diagram for describing a high-voltage power supply according to another embodiment of the present general inventive concept. For convenience of description, it is assumed that a board  410  has a box shape, and a first circuit and a second circuit are on the first region  411  and the second region  412  of the board  410 , respectively. The first region  411  and the second region  412  are separated by a bent region  413 . 
     According to the current embodiment, the board  410  includes a low-voltage input unit  420 , a controller  422 , a high-voltage generator  428 , and a high-voltage output unit  430 . The board  410  is prepared in a case  440 , and an insulator  450  is filled in the case  440 . Accordingly, a spark is prevented from being generated between contacts of the board  410 , specifically, between contacts grounded to a contact to which a high-voltage signal is applied, from among the contacts of the board  410 . 
     Since a spark is more frequently generated between contacts of a board on which a second circuit is formed than between contacts of the board on which a first circuit is formed, a following embodiment is also suggested so as to minimize the amount of an insulator and effectively prevent generation of a spark between contacts of the board. 
       FIG. 5  is a schematic diagram for describing a high-voltage power supply according to another embodiment of the present general inventive concept. For convenience of description, it is assumed that a board  510  has a box shape, and a first circuit and a second circuit are on the first region  511  and the second region  512  of the board  510 , respectively. The first region  511  and the second region  512  are separated by a bent region  513 . 
     According to the current embodiment, the board  510  includes a low-voltage input unit  520 , a controller  522 , a high-voltage generator  528 , and a high-voltage output unit  530 . The board  510  is prepared in a case  540 , and an insulator  550  is filled only in a space between the board  510  on which a second circuit is formed and the case  540  but not filled in a space between the board  510  on which a first circuit is formed and the case  540 . Accordingly, a spark is prevented from being generated between contacts of the board  510 , specifically, between contacts grounded with a contact to which a high-voltage signal is applied, from among the contacts of the board  510 . 
     In the high-voltage power supply according to the embodiments of the present general inventive concept, a first circuit, which receives a first voltage (a DC low-voltage signal) and generates a second voltage (an AC low-voltage signal) according to the first voltage, and a second circuit, which amplifies the second voltage with a predetermined gain, is on a board having a bent region (for example, a board having a box shape), instead of a flat board. Accordingly, areas of the board can be effectively used, and thus the high-voltage power supply can be minimized. Moreover, an electronic device, such as an image forming apparatus, including the high-voltage power supply can also be minimized. Additionally, other electronic devices having electronic components using DC high-voltage power signals, such as computers, telecommunications devices, radio transmission devices, televisions, electronic visual displays, home electronic appliances and other such electronic devices may be minimized. In addition, by covering the board, the first circuit, and the second circuit with an insulator or by covering an area of the board on which the second circuit is formed and the second circuit with the insulator, a spark does not generate in contacts of the board that are covered by the insulator. Accordingly, the contacts of the board do not need to be spaced apart from each other so as to prevent the spark, and thus the high-voltage supply can be minimized by more tightly integrating the first and second circuits. 
     Although a few embodiments of the present general inventive concept have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the present general inventive concept, the scope of which is defined in the claims and their equivalents.