Patent Publication Number: US-2005129416-A1

Title: Image-forming device to protect a paper feeder using a switch and method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application claims benefit from Korean Patent Application No. 2003-90964, filed on Dec. 13, 2003, the entire content of which is incorporated herein by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present general inventive concept relates to an image-forming device to protect a paper feeder using a switch and a method thereof, and more particularly, to an image-forming device and a method which can protect a paper feeder by mechanically intercepting a power supply to the paper feeder using a switch when the image-forming device malfunctions.  
      2. Description of the Related Art  
      Recently, with the spread and popularization of a computer, its peripheral devices have also been popularized. Such peripheral devices may be image-forming devices, such as printers, scanners, multifunctional devices, etc.  
      The structure of an image-forming device may be briefly divided into a controller part and an engine part. The controller part analyzes and stores image data transmitted from a computer in a RAM of a printer, communicates with the engine part so that the engine part can perform a printing operation, and then transmits the data stored in the RAM in a form of serial data.  
      The engine part includes an organic photo conductive drum, a laser scanning unit (LSU), a developer, a cleaning unit, a charge unit, a transfer unit, a fusing unit and so on. If the image data to be printed is received, the engine part performs the printing operation by performing processes of cleaning, charging, laser-scanning, writing, developing, transferring, fusing, etc., using such constituent elements.  
      Further, the engine part includes a feeder having a feeding cabinet (or feeding cassette), a pickup roller, and a driving motor for driving the pickup roller. If a printing command is inputted through the computer, the engine part supplies printing papers through a feeding unit and performs the above-described printing process, so that a desired document can be printed on the printing paper.  
      The image-forming devices recently used are mostly high-speed printers and digital multifunctional devices which typically adopt a large-capacity feeder which loads more than 500 printing papers. A feeding cassette of the large-capacity feeder adopts a technology that serves to lift up a paper loading unit using a motor so that printing papers are located in a feeding position if the printing papers are loaded on the loading unit. In this case, several sensors are required in order to accurately move the printing papers to the feeding position.  
       FIG. 1  is a block diagram illustrating a conventional image-forming device. Referring to  FIG. 1 , the conventional image-forming device includes a control unit  10 , a feeder  20  and a display unit  30 . The feeder  20  includes a motor control unit  21 , a driving voltage supply unit  23 , a feeding cassette  25 , and a sensor module  27 .  
      The control unit  10 , if a printing command is inputted from an external device, properly controls respective constituent elements of an engine part and supplies printing papers to the engine part by inputting a feeding command to the feeder  20  to perform a printing operation.  
      The feeding cassette  25  is a part that contains the printing papers, and includes a loading unit loaded with the printing papers and a motor for lifting the loading unit. If the feeding command is inputted, the motor control unit  21  lifts the loading unit up to a predetermined position (hereinafter, referred to as a “feeding position”) by driving the motor in the feeding cassette  25 .  
      The driving voltage supply unit  23  is a part which serves to supply a driving voltage of a predetermined level that is required by the motor control unit  21  to drive the motor of the feeding cassette  25 .  
      The sensor module  27  includes a sensor for sensing and confirming whether the feeding cassette is properly mounted on the image-forming device, a sensor for sensing and confirming whether the printing paper properly reaches the feeding position through a movement of the loading unit, and a sensor for sensing and confirming whether the printing papers exist in the feeding cassette  25 , so that the control unit  10  can properly control the motor control unit  21 .  
      If it is sensed by the sensor module  27  that the feeding cassette  25  is not properly mounted on the printing device, or the printing papers are insufficient, the control unit  10  outputs an error message for indicating a present state of the engine part through the display unit  30 , so that a user can be informed of the present state and take a proper step.  
      Meanwhile, in order to perform a large-capacity printing operation, the printing papers should continuously be fed. In this case, if the position of the printing paper escapes from the feeding position due to the reduction of the printing papers in the feeding cassette  25  as the printing operation is performed, this is sensed through the sensor module  27 , and the loading unit is properly lifted up, so that the printing work can continuously be done.  
       FIG. 2  is a flowchart illustrating an image-forming method of the conventional image-forming device of  FIG. 1 . Referring to  FIGS. 1 and 2 , if the image-forming device receives the printing command (operation S 81 ), the control unit judges through the sensor module  27  whether the feeding cassette  25  is properly mounted (operation S 82 ) and whether the printing papers exist in the feeding cassette  25  (operation S 83 ). If the feeding cassette is not properly mounted or no printing paper exists in the feeding cassette, the control unit outputs the corresponding error message to display the present state (operation S 86 ).  
      If the feeding cassette  25  is properly mounted and the printing papers exist in the feeding cassette, the control unit lifts up the loading unit using the motor so that the printing papers are located in the feeding position (operation S 84 ). If the printing papers are located in the feeding position (operation S 85 ), the control unit performs the printing operation (operation S 87 ).  
      That is, the control unit transfers the printing paper inside the feeding cassette using a pickup roller (operation S 87   a ), and prints a desired document on the transferred printing paper through a specified printing process (operation S 87   b ).  
      Then, it is checked whether the printing operation is completed (operation S 88 ). If so, the control unit operates to terminate the printing operation and to display the present state. Meanwhile, if the position of the printing paper escapes from the feeding position due to the reduction of the printing papers in the feeding cassette  25  as the printing operation is performed, the control unit confirms the position of the printing paper through the sensor module  27 , and controls the loading unit to continuously adjust the position of the printing papers (operation S 89 ).  
      According to the above conventional image-forming device and method, if the position of the printing papers is not accurately sensed due to an abnormal operation of the sensor module  27 , or if the motor is not stopped due to an abnormal operation of the motor control unit  21 , the loading unit in which the printing papers are loaded may continuously move in a direction of the feeding position.  
      This may cause the loading unit to collide with another feeder to bring a mechanical damage, and cause an overload of the motor in the feeding cassette  25  to cause a fire.  
     SUMMARY OF THE INVENTION  
      In order to solve the foregoing and/or other problems, it is an aspect of the present general inventive concept to provide an image-forming device and a method which can protect a paper feeder by intercepting a driving voltage to the paper feeder using a switch if the feeder is in an abnormal state.  
      Additional aspects and 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.  
      The foregoing and/or other aspects of the present general inventive concept may be achieved by providing an image-forming device which includes a motor to move a loading unit in which printing papers are loaded, a motor control unit to move the printing papers to a predetermined feeding position by driving the motor if a feeding command is received, a driving voltage supply unit to supply a driving voltage required for driving the motor to the motor control unit, and a switch to connect the driving voltage supply unit with the motor control unit to transfer the driving voltage from the driving voltage supply unit to the motor control unit, and to intercept the transfer of the driving voltage to the motor control unit if the loading unit moves over a predetermined range of a position thereof and becomes in contact with the switch.  
      In an aspect of the present general inventive concept, the image-forming device may further include a feeding cassette detection sensor to detect whether a feeding cassette provided with the loading unit and the motor is mounted on the image-forming device, a printing paper detection sensor to detect whether the printing papers are loaded in the loading unit, and a paper position detection sensor to detect whether the printing papers are located in the feeding position.  
      In another aspect of the present general inventive concept, the image-forming device may further include a power sensing unit to detect whether the driving voltage being supplied to the motor control unit is intercepted, a display unit to display predetermined messages on a screen, and a control unit to transmit the feeding command to the motor control unit if an external printing command is received, and to control the display unit to display an error message if it is detected that the driving voltage is intercepted.  
      In yet another aspect of the present general inventive concept, the switch may include a switch lever to extend over the feeding position on a moving path of the loading unit, and a switch contact to electrically connect the motor control unit with the driving voltage supply unit if the switch lever is connected to the switch contact, and to be physically disconnected from the switch lever if any one of the loading unit and the printing paper loaded in the loading unit comes into contact with the switch lever.  
      The foregoing and/or other aspects of the present general inventive concept may also be achieved by providing an image-forming method of an image-forming device having a loading unit loaded with printing papers and a motor to move the loading unit, the method including applying a driving voltage to the motor if a feeding command is received, moving the loading unit using the motor so that the printing papers reach a feeding position, performing a printing operation by feeding the printing papers, and stopping the motor by physically intercepting the driving voltage if the loading unit moves over a predetermined range of a position thereof.  
      In an aspect of the present general inventive concept, the image-forming method may further include judging whether the printing papers remain in the loading unit, and displaying a message to request a supplement of the printing papers.  
      In another aspect of the present general inventive concept, the image-forming method may further include detecting whether the driving voltage being supplied to the motor is intercepted, and displaying a predetermined error message if the driving voltage is intercepted.  
      In yet another aspect of the present general inventive concept that the applying of the driving voltage to the motor may include transferring the driving voltage to the motor through a switch lever extending over the feeding position on a moving path of the loading unit, and a switch contact connected to the switch lever.  
      In still another aspect of the present general inventive concept, the stopping of the motor may include disconnecting the switch contact from the switch lever by making any one of the loading unit and the printing paper loaded in the loading unit come into contact with the switch lever if the loading unit moves over the predetermined range of position.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      These and/or other aspects and advantages of the present 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 a conventional image-forming device;  
       FIG. 2  is a flowchart illustrating an image-forming method using the conventional image-forming device of  FIG. 1 ;  
       FIG. 3  is a block diagram illustrating an image-forming device according to an embodiment of the present general inventive concept;  
       FIG. 4  is a flowchart illustrating an image-forming method of an image-forming device according to another embodiment of the present general inventive concept; and  
       FIG. 5A-5D  are graphs illustrating operation states of respective constituent elements of the image-forming device of  FIG. 3 ; and  
       FIG. 6  is a view illustrating a switch of the image-forming device of  FIG. 3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Reference will now be made in detail to the 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.  
      The matters defined in the description such as a detailed construction and elements are nothing but the ones provided to assist in a comprehensive understanding of the invention. Thus, it is apparent that the present invention can be carried out without those defined matters. Also, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.  
       FIG. 3  is a block diagram illustrating an image-forming device according to an embodiment of the present general inventive, concept.  
      Referring to  FIG. 3 , the image-forming device may include a control unit  100 , a feeder  200  and a display unit  300 . The control unit  100  can properly control respective constituent elements (not illustrated) of a controller part upon receiving an external printing command and an engine part, and can transfer a feeding command to the feeder  200 .  
      The feeder  200  can include a motor control unit  210 , a switch  220 , a driving voltage supply unit  230 , a feeding cassette  240 , a sensor module  250 , and a power sensing unit  260 .  
      The feeding cassette  240  may be a cabinet that contains printing papers. Typically, the feeding cassette  240  can have a volume enough to contain about 250 to 500 printing papers, and various kinds of feeding cassettes can be provided in accordance with different sizes of the printing papers. The feeding cassette  240  can be generally provided with a loading unit  243  directly loaded with the printing papers and a motor  241  to transfer the printing papers to a feeding position by moving the loading unit  243 .  
      The motor control unit  210  can move the loading unit  243  by driving the motor  241  of the feeding cassette  240  upon receiving the feeding command from the control unit  100 , so that the printing papers move to the feeding position. A driving voltage to drive the motor  241  can be supplied through the driving voltage supply unit  230 .  
      Meanwhile, in order to accurately move the printing paper to the feeding position, the sensor module  250  should perform an accurate position detection. As shown in  FIG. 3 , the sensor module  250  can include a feeding cassette detection sensor  251 , a paper position detection sensor  253  and a printing paper detection sensor  255 . The feeding cassette detection sensor  251  can detect whether the feeding cassette  240  is properly mounted on the image-forming device. If the feeding cassette  240  is not properly mounted on the image-forming device, the feeding cassette detection sensor  251  can inform the control unit  100  that the feeding is impossible, and the control unit  100  can inform a user of this information through the display unit  300 .  
      The paper position detection sensor  253  can serve to detect a position of an uppermost printing paper loaded in the loading unit  243 . The position information sensed by the paper position detection sensor  253  can be inputted to the motor control unit  210 , and the motor control unit  210  can drive the motor  241  based on the inputted position information so that the printing papers are accurately located in a feeding position by moving the loading unit  243 . By continuously confirming the position of the printing paper during a printing operation, the motor control unit  210  can control the driving of the motor  241  so that the printing papers can be successively provided even if the number of the printing papers is reduced as the printing operation is performed.  
      Meanwhile, the printing paper detection sensor  255  can determine whether the printing papers exist on the loading unit  243 , and if no printing paper exists, the printing paper detection sensor  255  can inform the control unit  100  of this information, so that the control unit  100  controls the display unit  300  to display the non-existence of the printing paper.  
      If the paper position detection sensor  253  or the motor control unit  210  malfunctions and thus the driving of the motor  241  in the feeding cassette  240  is not stopped, the loading unit  243  may continue to move and collide with any constituent element in the feeder  200 , such as a pickup roller.  
      In this embodiment of the present general inventive concept, a switch  220  can be installed on a moving path of the loading unit  243 , and if the loading unit  243  moves over a predetermined position, the switch  200  is actuated to intercept the driving voltage being supplied to the motor  241  and thus to stop the motor  241 . As shown in  FIG. 3 , in a normal operation state, the switch  220  serves to connect the driving voltage supply unit  230  with the motor control unit  210  and to transfer the driving voltage to the motor control unit  210  to drive the motor  241 .  
      In an aspect of the present general inventive concept, the switch  220  can be a mechanical switch having a switch lever and a switch contact connected thereto. The switch lever can be installed in a proper position on the moving path of the loading unit, and if the loading unit  243  moves over the predetermined position, the loading unit  243  collides with the switch lever. If the loading unit  243  can collide with the switch lever, the switch lever can physically be disconnected from the switch contact, and the driving voltage being supplied to the motor  241  to move the loading unit  243  can be intercepted. Accordingly, the motor  241  can be stopped, and this causes the loading unit  243  not to move further.  
      The interception of the driving voltage as described above may be implemented by using a semiconductor switch or sensor. In this case, however, the semiconductor switch or sensor may cause the loading unit to malfunction. In an aspect of the present general inventive concept the mechanical switch can be adapted, so that the supply of the driving voltage to the motor can physically intercepted.  
      If the switch  220  is turned off due to the collision with the loading unit  243  or the printing paper, and the driving voltage being supplied to the motor driving unit  210  is intercepted, the power sensing unit  260  can detect and report this collision or interception to the control unit  100 .  
      The control unit  100 , which has received this report on the collision or interception, can determine that an error has occurred in the feeder  200 , and can generate a predetermined error message to report the error occurrence on the display unit  300 . The user may consider a plan to fix the error of the image-forming device after viewing the error message displayed on the display unit  300 .  
      Hereinafter, an image-forming method according to another embodiment of the present general inventive concept will be explained with reference to  FIG. 4 .  
      Referring to  FIGS. 3 and 4 , if the printing command is received (operation S 410 ), the control unit  100  can send the feeding command to the motor control unit  210 . If the feeding command is received, the sensor module  250  can detect whether a feeding operation can be performed. Specifically, the sensor module  250  can detect whether the feeding cassette  240  is mounted using the feeding cassette detection sensor  251  (operation S 421 ), and then detects whether printing papers remain in the feeding cassette  240  (operation S 423 ). This printing paper detecting operation may be performed later. Meanwhile, if there is any trouble for the feeding cassette or the feeding papers, it is displayed through the display unit  300  (operation S 460 ).  
      If it is detected that the printing papers remain in the feeding cassette  240 , the motor control unit  210  can drive the motor  241  in the feeding cassette  240  to lift up the loading unit  243  (operation S 431 ). This lifting operation continues until the printing paper reaches a proper feeding position, and if it is judged that the printing paper reaches the feeding position, the motor control unit  210  can stop the motor  241  (operation S 433 ).  
      In the above process, if the loading unit  243  moves over the feeding position and collides with the switch lever of the switch  220 , the driving voltage supply unit  230  can be disconnected from the motor control unit  210 , and thus the driving voltage being supplied to the motor  241  can be intercepted (operations S 440  and  450 ).  
      If the motor  241  is stopped by the interception of the driving voltage, the power sensing unit  260  can detect and inform the control unit  100  of this interception of the driving voltage, and the control unit  100  can display the error message through the display unit  300  (operation S 460 ).  
      Meanwhile, if the motor  241  is normally driven without any collision with the switch lever and the printing paper reaches the feeding position, the feeding of the printing paper can be performed (operation S 471 ). Specifically, a paper pickup roller can pick up and transfer the printing papers to a registration roller, and the registration roller arranges and moves the printing papers to a fusing roller in synchronization with image data inputted from the controller part.  
      Then, the printing operation can be performed together with the feeding operation (operation S 473 ). Specifically, as the printing paper moves, the processes of cleaning, charging, laser-scanning, writing, developing, transferring, fusing, etc., can be successively performed.  
      Meanwhile, in a case of a successive printing operation (operation S 480 ), the paper position detection sensor  253  can determine whether the printing papers are in the proper feeding position by continuously detecting the position of the printing papers, and can control the motor  241  to perform a successive feeding operation (operation S 490 ).  
       FIGS. 5A-5D  are graphs illustrating operation states of respective constituent elements of the image-forming device of  FIG. 3 .  
       FIG. 5A  shows the operation state of the feeding cassette detection sensor  251 . It can be seen from  FIG. 5A  that the feeding cassette detection sensor  251  can detect the feeding cassette mounted on the image-forming device at a time point t 1 , and can output a detection signal at the time point t 1 .  FIG. 5B  shows a waveform of an output voltage of the paper position detection sensor  253 . It can be seen from  FIG. 5B  that the printing paper can reach the feeding position at a time point t 2 . In the case of the successive printing operation, the paper position detection sensor  253  can detect that the printing paper escapes from the feeding position during a period of t 3 ˜t 4  due to a reduction of the printing papers, and output a detection signal.  
       FIG. 5C  shows a waveform of an output voltage of the motor control unit  210 . It can be seen from  FIG. 5 ( c ) that the motor control unit  210  can lift up the loading unit  243  by driving the motor  241  during a period of t 1 ˜t 2  since it is detected that the feeding cassette  240  is properly mounted at the time point t 1  and the printing paper does not reach the feeding position until the time point t 2 . After the time point t 2  when it is detected that the printing paper reaches the feeding position, the motor control unit  210  can prevent the driving voltage from being supplied to the motor  241  to fix the loading unit  243 .  
      In this case, as shown in  FIG. 5C , the motor control unit  210  can output again the motor driving voltage during periods of t 3 ˜t 4  and t 5 ˜t 7 . Referring to  FIG. 5B , in the period of t 3 ˜t 4 , the printing paper escapes from the feeding position, and this refers to a normal operation period of the motor control unit  210 . However, in the period of t 5 ˜t 7 , the motor can be driven even though no detection signal is outputted, and this period of t 5 -t 7  refers to an abnormal operation period of the motor control unit  210 . This abnormal operation of the motor control unit  210  may cause a collision between the constituent elements of the image-forming device.  
       FIG. 5D  shows the operation state of the switch to prevent the collision. It can be seen from  FIG. 5D  that until the time point t 5 , the feeder  200  can perform a normal operation, and the driving voltage supply unit  230  and the motor control unit  210  can be connected to each other through the switch  220 . However, from the time point t 5 , the feeder  200  can perform the abnormal operation, and the motor  241  can continuously be driven during the period of t 5 ˜t 7 . In this case, even if the loading unit  243  moves over the feeding position, it can collide with the switch lever at the time point t 6 , which is before the time point t 7 , and this causes the switch lever to be disconnected from the switch contact. Accordingly, after the time point t 6 , the supply of the driving voltage can be intercepted, and thus the motor can be stopped. As a result, the damage of the internal elements of the image-forming device can be prevented even if the error occurs in the feeder  200 .  
       FIG. 6  is a view illustrating the switch  220  of the image-forming device of  FIG. 3 . Referring to  FIG. 6 , a switch contact  220   a  can be connected between the motor control unit  210  and the driving voltage supply unit  230  and can be turned on and off to selectively supply the driving voltage from the driving voltage supply unit  230  to the motor control unit  210 . A switch lever  220   b  selectively contacts the loading unit  243  moving from a first position to a second position (feeding position) so that the switch contact  220   a  is turned on and off, thereby selectively supplying the driving voltage from the driving voltage supply unit  230  to the motor control unit  210 .  
      As described above, according to an aspect of the present general inventive concept, even if a motor to feed printing papers becomes uncontrollable due to an abnormal operation of a motor control unit or a sensor module, and a printing paper or a loading unit in which printing papers are loaded is continuously lifted, a collision between constituent elements of an image-forming device or an overload of the motor can be prevented by mechanically intercepting a motor driving voltage being supplied to the motor. Such a switch can be implemented by a simple switch lever and contacts, and can operate without a trouble even if an error occurs in electronic circuits.  
      Although a few embodiments of the present general inventive concept have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in the appended claims and their equivalents.