Method and apparatus for controlling high-voltage output in image forming system

A method and an apparatus to control a high voltage output in an image forming system. The method includes setting a master processor to control an engine, and setting a slave processor to control a high voltage output; transmitting a command, which includes a timing and a level of the high voltage output, from the master processor to the slave processor; and determining the timing and level of the high voltage output after analyzing the received command, and controlling the high voltage output according to a predetermined high voltage output synchronization signal by the slave processor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Korean Patent Application No. 2003-53907, filed on Aug. 4, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image forming system, and more particularly, to a method and an apparatus to control a high voltage output while reducing loads on a main processor in an engine controlling module by simplifying a control signal line.

2. Description of the Related Art

In an image forming system using an electro-photographic method, when light corresponding to image information is scanned by an exposure device onto a photosensitive medium which is thus charged to a predetermined electric potential, an electrostatic latent image is formed on the photosensitive medium. Then, a developer provides toner on the electrostatic latent image to form a toner image. In a color electro-photographic method, four developers, each of which contains a color toner such as cyan, magenta, yellow, and black, are required to form an image. The formed toner image is transferred to a sheet of paper directly from a photosensitive medium or by passing through an intermediate transfer medium. When the transferred toner image passes through a fuser, the toner image is fused on the paper by heat and pressure. The mono-color image or multiple color image is printed on the paper via the above processes.

A color image can be formed with, for example, a single-pass method, wherein four exposure units and four photosensitive media are used, or a multi-pass method, wherein one exposure unit and one photosensitive medium are used. In both methods, four color toners as described above are required. The printing speed in the single-pass method is the same for mono-color printing and multiple color printing, thus high speed color printing can be performed. In the multi-pass method, it takes at least four times longer to print a multiple color image as opposed to a mono-color image. However, a printing operation in the multi-pass method can be performed with an apparatus having a simpler structure than that used to perform a printing operation in the single-pass method.

In the above image forming system, a plurality of high voltages are required to charge, develop, transfer, clean, and paper adsorb. In the single-pass method, 20 pulse width modulation output ports including 4 ports to supply charging high voltage, 4 ports to supply developing high voltage, 4 ports to supply a first transfer high voltage, 4 ports to supply cleaning high voltage, and 2 ports to supply paper adsorbing high voltage, and 19 control ports are required. On the other hand, the multi-pass method requires 4 PWM output ports including a port to supply charging high voltage, one port to supply developing high voltage, one port to supply a first transfer high voltage, and one port to supply second transfer high voltage, and control ports corresponding to the PWM ports.

In the single-pass method, since more control ports for high voltage output are used, more control signal lines between a main processor including an engine controlling module and a high voltage output module are required. Additionally, more pins are necessary and a total length of a harness increases. Thus, the single-pass method has disadvantages such as high fabrication cost and high sensitivity to errors due to various noises. Also, since control signals of the high voltage output module are generated in the main processor of the engine controlling module, the main processor should operate the engine and control the high voltage output simultaneously. Thus, an expensive main processor operating at a higher speed is required.

SUMMARY OF THE INVENTION

Accordingly, it is an aspect of the present invention to provide a method and an apparatus to control a high voltage output, while reducing loads on a main processor in an engine controlling module, by simplifying a control signal line, and an image forming system using the method and apparatus.

The foregoing and/or other aspects of the present invention may be achieved by providing a method of controlling a high voltage output in an image forming system, the method including setting a master processor to control an engine, and setting a slave processor to control the high voltage output, transmitting a command, which includes a timing and a level of the high voltage output, from the master processor to the slave processor, receiving and analyzing the transmitted command by the slave processor; and deciding the timing and the level of the high voltage output, and controlling the high voltage output according to a predetermined high voltage output synchronization signal received by the slave processor.

The method of controlling a high voltage output may further include measuring detection values for environment recognition in the image forming system during a predetermined time, and transmitting the measured values to the master processor by the slave processor, and controlling the timing and the level of the high voltage output according to the command transmitted by the master processor.

The foregoing and/or other aspects of the present invention may also be achieved by providing an apparatus to control a high voltage output in an image forming system, the apparatus including: a first memory storing a control program and a timing and a level of the high voltage, which are used in a previous printing operation; a master processor performing engine controlling operations using the control program stored in the first memory, and transmitting a command including the timing and the level of the high voltage output stored in the first memory; a slave processor deciding the timing and the level of the high voltage output by analyzing the generated command, which is received from the master processor, and controlling the high voltage output according to a high voltage output synchronization signal; and a second memory storing the timing and the level of the high voltage output decided by the slave processor.

The foregoing and/or other aspects of the present invention may also be achieved by providing an image forming system including an image processor converting printing data, which is received from a computer requiring a printing operation, into image data driving an engine, an engine controller receiving the image data from the image processor, performing an engine controlling operation using a predetermined control program, and generating a command including a timing and a level of a high voltage output, a high voltage controller deciding the timing and the level of the high voltage output by analyzing the generated command, which is received from the engine controller, and controlling the high voltage output according to a predetermined high voltage output synchronization signal, a high voltage output unit generating and outputting a plurality of high voltages required in the printing operation under the control of the high voltage controller, and an engine unit forming an image on a sheet of paper from the image data provided from the engine controller using the high voltage output provided from the high voltage output unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1is a side cross-sectional view of an image forming system using a method of controlling a high voltage output of the present invention. The image forming system includes a loading device110, a pickup device120, a paper feeding device130, an exposure device140, a developing device150, a transfer device160, a fusing device170, and a paper discharging device180.

Referring toFIG. 1, the loading device110, which generally includes a cassette to carry sheets of paper therein, is removably installed in a lower portion of a main body100. The paper P is picked up by the pickup device120, which is rotatably installed to rotate in the main body100, and carried inside the main body100in a direction of the arrow.

The pickup device120generally includes a pickup roller to draw the paper P out of the loading device110. The paper feeding device130generally includes a paper feeding roller to carry the paper P drawn out of the loading device110into the main body100. A paper feeding sensor131detects a front end of the paper P, and senses whether the pickup operation of the paper P from the loading device110is successfully performed by the pickup device120according to a detection result of the front end of the paper P.

The exposure device140scans light corresponding to an image signal onto a photosensitive drum151, charged to have a uniform potential, to form an electrostatic latent image. The exposure device140generally includes a laser scanning unit, which uses a laser diode as a light source, and a light window141, through which the laser beam radiated from the laser diode is radiated outward, is disposed to face the photosensitive drum151.

The developing device150includes a plurality of ink cartridges, which are installed to contact the photosensitive drum151to develop the electrostatic latent image formed on a surface of the photosensitive drum151into a predetermined color image by the exposure device140in response to the image signal. A developing agent stored in the plurality of ink cartridges overlaps on the electrostatic latent image formed on the photosensitive drum151, thus forming a predetermined visible image.

The transfer device160includes a transfer belt162, which is supported by a plurality of transfer belt backup rollers161and rotates in a closed loop shape and on which the toner image formed on the surface of the photosensitive drum151is transferred. The transfer device160further includes a transfer roller163, which is installed to face one of the plurality of transfer belt backup rollers161to hold the transfer belt162therebetween to press the paper P toward the transfer belt162. Therefore, the color toner image transferred from the photosensitive drum151to the transfer belt162is re-transferred onto the paper P. Here, it is desirable that a traveling linear velocity of the transfer belt162be equal with a rotation linear velocity of the photosensitive drum151. Also, a length of the transfer belt162should be the same or longer than the paper P, on which the color toner image is finally transferred.

In the transfer device160, the transfer roller163is installed to face the transfer belt162. The transfer roller163is separated from the transfer belt162while the color toner image is transferred on the transfer belt162, and contacts the transfer belt162when the color toner image is completely transferred onto the transfer belt162, to transfer the image onto the paper P.

The fusing device170includes a fusing roller171, and a pressing roller172, which is installed to face the fusing roller171to hold the conveyed paper P therebetween and press the paper toward the fusing roller171. The fusing roller171fuses the visible image on the paper P by heating the paper P, on which the visible image is formed. The paper discharging device180generally includes a paper discharging roller to discharge the paper, on which the visible image is formed, outwardly. In order to perform a duplex printing, the paper discharging roller is inversely rotated, and the paper P is reversed and transferred on a reverse path.

FIG. 2Ais a block diagram of an apparatus to control a high voltage output according to an embodiment of the present invention. The apparatus includes an image processor210, an engine controller220, a high voltage controller230, a high voltage output unit240, and an engine unit250.

Referring toFIG. 2A, the image processor210converts printing data, which is received from an external device connected to a communication interface, for example, a personal computer (PC), into image data. The image data is suitable for the operation of the engine unit250, according to printing conditions set in a printer driver, and stores the image data in an internal or external storing medium. The storing medium stores various control programs required to implement functions of the image forming system, various data generated by the image processor210, and the printing data and printing information received from the personal computer.

The engine controller220controls the high voltage controller230and the engine unit250, so that an image corresponding to the image data received from the image processor210is printed on the paper. When the engine controller220receives a command for printing from the image processor210, the engine controller220controls the engine unit250so that various devices120through180are prepared to perform the printing operation. Preparations for the printing operation may include rotation of a polygonal rotating mirror or a scan disk, that is, a deflection unit of the exposure device140at a predetermined speed required during the printing operation, heating of the fusing device170to a predetermined temperature, or inspections of the devices120,130,140,160,170and180. Therefore, when the engine controller220decides that the printing operation can be performed via the preparations of the printing operation after receiving the command for printing from the image processor210, the engine controller220applies a printing start signal to the image processor210and provides the exposure device140with the image data stored in the storing medium through the engine controller220.

The high voltage controller230analyzes the command received from the engine controller220to decide a predetermined timing and output level for the high voltage output, and provides the high voltage output unit240with the decided time and output level.

The high voltage output unit240generates charging high voltage, developing high voltage, first and second transferring high voltages, cleaning high voltage, or paper adsorbing high voltage, and provides each device of the engine unit250with the generated high voltage. Here, PWM ports and controlling ports disposed between the devices of the high voltage output unit240and the engine unit250operate according to the high voltage output timing and control duties of PWM signals. The ports decide whether the high voltage is output or not while changing a high voltage output level, or to decide whether the high voltage is output or not via an on/off controlling operation in a case where the high voltage output level is fixed.

The engine unit250includes various devices required to perform the printing operation, i.e., the pickup device120, the paper feeding device130, the exposure device140, the developing device150, the transfer device160, the fusing device170, and the paper discharging device180shown inFIG. 1. The engine unit250may have various structures according to the printing method.

FIG. 2Bis a block diagram of detailed structures of the engine controller220and the high voltage controller230ofFIG. 2A. The engine controller220includes a master processor221and a first memory222, and the high voltage controller230includes a slave processor231and a second memory232.

Referring toFIG. 2B, the master processor221in the engine controller220controls the entire operation of the engine unit250according to a control program stored in the first memory222. The master processor221also provides the slave processor231in the high voltage controller230with a synchronization signal to output high voltage, the high voltage output timing, and the high voltage output level stored in the first memory222. The synchronization signal for the high voltage output may be generated when the paper feeding sensor131senses the paper P, or may be generated by a page synchronization signal, which is generated when the first transfer operation is performed on the paper after the sensor131senses the paper. The first memory222stores image data, various control programs, developing conditions, timing for high voltage output and high voltage output level provided from the image processor210. The developing conditions stored in the first memory222are updated at every printing operation.

In the high voltage controller230, the slave processor231analyzes the command, which includes the synchronization signal for the high voltage output, provided from the master processor221, to generate a control signal for the high voltage output including a high voltage output timing and output level with respect to each color, and provides the control signal for the high voltage output to the high voltage output unit240. The second memory232may include an EEPROM, and stores the high voltage output timing and the high voltage output level decided by the slave processor231.

Communication between the master processor221and the slave processor231may be performed by a wired serial communication such as a serial input output or a universal asynchronous receiver/transmitter, or by a wireless radio frequency communication. In the wired serial communication, the number of wires can vary if a communication between the master processor221and the slave processor231meets a predetermined interface protocol. Here, a control signal line between the master processor221and the slave processor231includes a transmission signal, a receive signal, and a synchronization signal.

In the above structure, since the slave processor231is an independent module, which is different from the master processor221, it is easy to re-design the slave processor231even when a platform of the master processor221is changed. In addition, since the number of pins in a harness, which is used in the communication between the master processor221and the slave processor231, is reduced, noise is reduced. Also, since the slave processor231actually performs the control of the high voltage, usable time of the master processor221increases and the master processor221can be realized by a processor having a low price.

FIG. 3is a flow chart of a method of controlling a high voltage output according to the embodiment of the present invention.

Referring toFIG. 3, the system is initialized when the power of the image forming system is turned on. When the initialization is completed in operation310, the high voltage output timing and the high voltage output level are transmitted from the master processor221of the engine controller220to the slave processor231of the high voltage controller230in operation320. Here, if the high voltage output timing and level with respect to the previous printing operation are stored in the slave processor231, operation320may be omitted.

When the transmission of the high voltage output timing and level is completed from the master processor221to the slave processor231in operation320, if the high voltage output synchronization signal is supplied from the master processor221, the slave processor231controls the high voltage output unit240according to the high voltage output timing in operation330.

The slave processor231measures a detection value for environment recognition in the image forming system and transmits the value to the master processor221, so that the high voltage timing and level can be controlled by the master processor221depending on an elapsed lifespan of the engine unit250.

Referring toFIG. 4, in operation410, it is determined whether the power of the image forming system is turned on/off. If the power of the image forming system is turned on, developing conditions of the previous printing operation are downloaded from the master processor221to the slave processor231in operation420.

The master processor221controls the devices120,130,140,150,160and180of the engine unit250to be prepared to perform the printing operation in operation430, and decides whether the preparations for the printing operation are completed or not. If the preparations for the printing operation are completed in operation440, it is decided whether a printing instruction command is input in operation450. If the printing instruction command is input, operation320is performed.

FIG. 5is a flow chart of sub-operations of operation320shown inFIG. 3. Referring toFIG. 5, it is decided whether the slave processor231requires the master processor221to transmit the high voltage output timing and level.

If the slave processor231requires the master processor to transmit the high voltage output timing and level in operation510, the master processor221generates commands corresponding to the high voltage output and level, which are stored in the first memory222, and transmits the commands to the slave processor231in operation520. On the other hand, if the slave processor231does not require the master processor to transmit the high voltage output timing and level, it means that the high voltage output timing and level, which are used in the previous printing operation, are stored in the second memory232.

The slave processor231analyzes the commands transmitted from the master processor221to decide the high voltage output timing and level, and stores the timing and level in the second memory232. Outputs of the high voltage are set in operation540according to the high voltage output timing and level decided in operation530.

It is monitored that the high voltage output synchronization signal is transmitted from the master processor221in operation550. In a case where the high voltage output synchronization signal is not transmitted within a predetermined time in operation550, it can be decided that a jam is generated, and predetermined operations for processing the jam are performed and operation440in the initialization process is performed. If the high voltage output synchronization signal is transmitted from the master processor221within a predetermined time in operation550, the PWM ports corresponding to the devices of the engine unit250are controlled according to the high voltage outputs in operation560.

FIG. 6is a flow chart of sub-operations of operation340shown inFIG. 3. Referring toFIG. 6, detection values for environment recognition of the image forming system are measured at every predetermined time by the engine unit250, since the image forming system is operated in operation610. The detection values may be roll resistance values of the charging roller, the first transfer roller, and the second transfer roller. The roll resistance values are changed due to elements such as the elapsed lifespan of the system, and rising of the inner temperature of the system, and accordingly, the charging high voltage, or the first and second transfer high voltages should be controlled. The measured detection values are converted into digital data via an analog/digital conversion operation.

In operation620, an average value of the detection values, which are measured N times in operation610, is calculated by the slave processor231, and the average value of the detection values is stored in the second memory232in operation630. The slave processor231decides whether the detection values must be transmitted to the master processor221or not in operation640. If a difference between the average value, which is previously stored in the second memory232, and the average value of the detection values, which is calculated in operation620, is in a predetermined tolerance range, the detection values are not transmitted to the master processor221. However, the difference between the average values is out of the predetermined tolerance range, the detection values are transmitted to the master processor221in operation650.

In a case where the detection values are transmitted to the master processor221, the slave processor231transmits the detection values to the master processor221, and the master processor221controls the high voltage output timing and level according to the received detection values and stores the controlled timing and level in the first memory222.

The method of controlling high voltage output according to the present invention can be applied to numerous image forming systems, regardless of the image forming methods such as the single-pass method and the multi-pass method.

The method of the present invention can be realized as a computer-readable code in a computer-readable recoding medium. The computer-readable recording medium includes all kinds of recording media, in which the computer-readable data is stored. The recording medium may be a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, or an optical data recording medium, or also can be realized as a carrier wave. Also, the computer-readable paper is distributed to the computer systems connected by a network, and can store and perform the computer-readable code in a distributed way. In addition, functional program, code, and code segment for realizing the present invention can be easily detected by those skilled in the art.

According to the present invention, the control signal line between the engine control module and the high voltage output module is simplified, thus simplifying the equipment such as the harness. As such, since a structure of the harness can be simplified, assembly and fabrication of the system can be made conveniently, thus reducing the fabrication cost. Also, since the high-voltage output module is operated independently from the engine control module, the system can be realized using a low price master processor having low operational speed, and it is easy to re-design the high voltage output module when the platform of the master processor is changed. Also, PWM clock signals included in the control signal line between the engine control module and the high voltage output module can be reduced, thus an additional driver is not required and an electromagnetic interference output level can be reduced.