Patent Document

CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Patent Application No. 2001-70013, filed Nov. 12, 2001, in the Korean Industrial Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an image scanning device, and more particularly, to a method and an apparatus for detecting an error in an image scanning device, determining either the exchange of a light source or the presence of a contaminant in an optical path and then informing of the result of the determination. 
     2. Description of the Related Art 
     Generally, an image scanning apparatus is incorporated in a copier, a facsimile machine and a copier-facsimile system. One example of the image scanning apparatus is shown in FIG.  1 . 
     FIG. 1 shows an image scanning apparatus disclosed in U.S. Pat. No. 5,978,614, to Takeuchi, issued Nov. 2, 1999, and FIG. 2 is a flowchart showing a method of measuring a quantity of light of a lamp by using the image scanning apparatus of FIG.  1  and informing of a time for lamp replacement. 
     Referring to FIG. 1, the image scanning apparatus includes a scanning table unit  11  provided to scan a sheet of document placed on a scanning plate  10 , and a document feeding unit  12  automatically feeding a plurality of sheets of documents for an automatic and sequential scanning of the documents. First and second scanning units  13  and  14  are driven within the stand-by position P 1 , white panel position P 2 , and first and second scanning start positions P 3  and P 4 . The first and second scanning units  13  and  14  are changed to a standby mode when moving to the standby position P 1  by a certain translating means, scan the white panel  15  in the white panel position P 2 , and scan the document in the first and second scanning positions P 3  and P 4 . 
     Referring to FIG. 2, in a so-called Flat Bed Scanner (FBS) that performs a scanning operation by using the scanning table unit  11 , a controller determines whether a start key is selected from a user&#39;s manipulation of keys in operation S 10 . If the start key is determined as being selected, the first scanning unit  13  moves to the second scanning position P 4  in operation S 11 . Next, the first scanning unit  13  scans the document while moving to a job completion position P 5 , and at the same time, the image data obtained upon scanning the document is stored in a storage means in operation S 12 . Then the first scanning unit  13  moves to the white panel position P 2  in operation S 13 . The white panel  15  is scanned and detected by a charge coupled device (CCD) sensor  17  in operation S 14 . 
     The controller determines whether or not white pixels of the image data of the scanned document are less than 90% of a predetermined reference in operation S 15 . When the white pixels of the image data are greater than 90% of the reference, the controller determines a light source  16  emits light appropriately, and compensates the data stored in S 12  and prints an image on the sheets in operation S 16 . Then the first scanning unit  13  moves to the standby position P 1  in operation S 17 . 
     When the white pixels of the image data are less than 90% of the reference, the controller determines whether the light source  16  emits the light inappropriately. And in this case, the controller deletes the image data stored in the storage means in operation (step S 18 ). Then the controller indicates through a certain display device a need for a lamp replacement in operation (step S 19 ). Accordingly, the user notices the message in the display and replaces the lamp with a new one so as to maintain the appropriate scanning. 
     A so-called Automatic Document Feeder (ADF) performs the scanning operation by using the document feeding unit  12 , in a similar manner as the scanning operation of the FBS. The only difference between the FBS and the ADF is that the ADF first scans the white panel  15 , scans the document, and then compares/determines the white pixels of the image data. This is generally because the white panel  15  is placed between the document scanning positions of the FBS and the ADF. 
     According to the conventional image scanning apparatus as described above, the controller determines that the light quantity of the lamp is inappropriate if the white pixels of the image data of the scanned white panel are less than 90% of the reference. However, the white pixels are sometimes determined as being less than 90% of the reference when there are contaminants disposed in the optical path having a white panel, a mirror, etc. 
     If the message for the replacement of the lamp is due to the contaminants contained in the optical path, it would be disadvantageous for the user to buy a new lamp that is not actually required. Also, if there is not a sufficient quantity of light due to the presence of the contaminants, the light quantity will still be insufficient even if the user replaces the lamp with a new one. 
     Also, even when the light quantity of the lamp drops, if taking into account of the fact that the amplifier could compensate the lamp, the detection of error of the scanning apparatus can hardly be accurate only by comparing and determining the light quantity of the lamp. 
     SUMMARY OF THE INVENTION 
     The present invention has been made to overcome the problems of the related art, and accordingly, it is an object of the present invention to provide a method of detecting an error in an image scanning device, which is improved so as to distinguish a need for a lamp replacement from a contamination of an optical path, and inform the result of the detection accordingly. 
     Additional objects and advantageous of the invention 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 invention. 
     The above and other objects are accomplished by a method of detecting an error in an image scanning device that obtains image data when a document is scanned by using a light beam radiated from a lamp according to the present invention. The method includes a setting operation of obtaining initial reference values of a light quantity of the lamp and storing the obtained initial reference values in a memory, a storing operation of measuring the light quantity of the lamp during use of an image scanning system, obtaining measured values for comparing with the initial reference values, and storing the measured values in the memory, and a comparing/determining operation of determining whether to check a presence of error in the lamp or to check a presence of contaminant in an optical path by comparing the initial reference values with the measured values. 
     The setting operation includes scanning a white panel, extracting a light quantity from the scanned white panel, calculating a reference value R and an initial average value A from the extracted light quantity of the white panel, storing the calculated reference value R and the initial average value A in the memory, dividing the white panel into a number of pixel divisions n, and calculating initial divisional values B 1 ˜Bn of light quantities of the respective pixel divisions and storing the calculated initial divisional values B 1 ˜Bn in the memory. 
     The storing operation includes extracting a light quantity of a white value by scanning a white panel, obtaining measured average value a and a minimum value m of the light quantity from the extracted light quantity of the white value, storing the obtained average value a and the minimum value m in the memory, dividing the white value into divided values of pixel divisions n, and calculating measured divisional values b 1 ˜bn of the light quantity of the respective n pixel divisions n and storing the calculated measured divisional values b 1 ˜bn in the memory. 
     A first checking operation is further provided in the comparing/determining operation, for checking a presence of abnormality of the lamp when a difference between the initial reference values and the measured values is more than a predetermined reference. 
     The first checking operation includes searching the pixel divisions n for a pixel division to which the minimum value m falls; determining whether the pixel division having the minimum value m is a first division or a nth division, such as a last division, the first and nth divisions disposed at opposite outside portions of the white panel, comparing and thus determining whether the minimum value m is smaller than the calculated reference value R, when the pixel division having the minimum value m is the first or the nth division, and displaying an urging message for a lamp replacement when the minimum value m is smaller than the reference value R. 
     A second checking operation is also provided either when the pixel division having the minimum value m is not the first nor the nth division, or when the minimum value m is smaller than the reference value R, wherein the second checking operation includes checking the presence of contaminants in the optical path. 
     The second checking operation is also provided after the display of the urging message for the lamp replacement, and includes checking the presence of contaminants in the optical path. 
     The second checking operation includes comparing the initial divisional average values B 1 ˜Bn of the light quantity of the respective pixel divisions n with the measured divisional average values b 1 ˜bn of the light quantity of the respective pixel divisions, respectively, determining whether there is a pixel division where a difference between the initial average values B 1 ˜Bn and the measured divisional values b 1 ˜bn is greater than a predetermined reference, and displaying a message indicating a contamination of the optical path when there is the pixel division having the difference of the initial divisional values B 1 ˜Bn, b 1 ˜bn greater than the predetermined reference. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects and advantages of the present invention will be more apparent and more readily appreciated from the following description of the preferred embodiment of the present invention, taken in conjunction with the accompanying drawings, of which: 
     FIG. 1 is a schematic sectional view showing a conventional image scanning apparatus; 
     FIG. 2 is a flowchart for explaining a method of checking the conventional image scanning apparatus for a time for lamp replacement; 
     FIG. 3 is a block diagram of an image scanning apparatus according to an embodiment of the present invention; 
     FIG. 4 is a view showing a scanning unit of the image scanning apparatus of FIG. 3; 
     FIG. 5 is a flowchart explaining a method of detecting an error in an image scanning device according to an embodiment of the present invention; 
     FIG. 6 is a flowchart explaining a system setting mode of FIG. 5; 
     FIG. 7 is a graph showing the quantity of light measured when there is a need for lamp replacement; 
     FIG. 8 is a flowchart explaining a comparing/determining operation of FIG. 5; and 
     FIG. 9 is a graph showing the quantity of the light measured when there is contamination in an optical path of the image scanning device of FIG.  5 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described in order to explain the present invention by referring to the figures. 
     From now on, the present invention will be described in greater detail by referring to the appended drawings. 
     FIG. 3 is a block diagram showing an image scanning device according to an embodiment of the present invention. The scanning device includes a charge coupled device (CCD) sensor  31  that receives a signal generated from a document scanned by using a scanning unit  20 , an amplifier that amplifies the received signal of the CCD sensor  31  by a predetermined amount, an A/D converter  33  that converts the amplified analogue signal into a digital signal, a controller  36  that stores the digitalized image in a storage unit  34  and controls so that the data can be edited or outputted by an image processor  35  and an operation panel  39  having a key input portion  37  operable by a user and a display  38 . 
     The controller  36  controls a general document reading operation by controlling the driving of the scanning unit  20  according to a control program. The controller  36  controls so as to move a first carriage  23  having a lamp  21  and a mirror  22  and a second carriage  25  having mirrors  25   a,  which are shown in FIG.  4 . The controller  36  also controls the driving of the lamp  21  so as to scan a document  24 . 
     The storage unit  34  includes a RAM or EEROM, and stores various data generated during the execution of the program, and various reference data. 
     The key input portion  37  has numeral keys and function keys for operation of the respective components, and generates and sends to the controller  36  the data required for controlling the image scanning device. 
     The display  38  is an indicating device such as a Liquid Crystal Display (LCD), and displays a certain message while being driven by the controller  36 . 
     In FIG. 4, a reference numeral  26  denotes a white panel, and a reference numeral  27  denotes a condensing lens. The scanning unit  20  shown in FIG. 4 is a typical example of a so-called optical path moving type of a reduced optical system that scans the image while the first and second carriages  23  and  25  move along the optical path. 
     During driving of the image scanning device constructed as above, a method distinguishes the need for a lamp replacement from the existence of contaminants in the optical path and selectively indicates either the need for the lamp replacement or the existence of the contaminants in the optical path. 
     Referring to FIG. 5, first, the entire system of the image scanning device is set in operation S 20 . The operation S 20  is performed through a key manipulation at the time of shipping the product, or in a serviceman mode, i.e., when some parts are replaced or repaired. In this embodiment, initial references for the lamp  21  are obtained and stored in the storage unit  34 . The operation S 20  will be described in detail in a later part of the description and FIG.  6 . 
     With the system being set as described above, the user turns the power on to use the device in operation S 21 . Accordingly, by a control program, the data are initialized, and the image scanning device is ready for the scanning operation in operation S 22 ). 
     Next, the quantity of light of the lamp  21  is measured, and the comparison/determination operation is selectively performed as to whether the lamp  21  operates appropriately or there are contaminants in the optical path including the white panel  26  in operation S 23 . 
     In the operation S 23 , appropriate measures are taken according to the result of the comparison/determination operation to perform a normal scanning operation of the image scanning device. That is, the component can be replaced, repaired, or the device can be cleaned to remove the contaminants disposed in the optical path. The detailed description about the operation S 23  will be made in a later part of the description and FIG.  8 . 
     After the operation S 23 , the controller  36  determines whether an operation start command has been input through the key input or the like in operation S 24 , and performs the corresponding operation according to the key input in operation S 25  That is, the controller  36  either performs the scanning by driving the scanning unit  20 , or performs operations like print, copy, etc., by driving the image processor  35 . 
     After the operation S 25 , the system is in a standby mode. The controller  36  compares/determines whether a counting time Tc counted from the operation S 23  till the standby mode exceeds a predetermined reference time Ts, i.e., 24 hours for example in operation S 26 . When it is determined that the counting time Tc exceeds the reference time Ts, the operation S 23  repeats, and if not, the device is in the standby mode until the key input. 
     The system setting mode in the operation S 20  will be described in greater detail below with reference to FIG.  6 . 
     The setting mode in the operation S 20  is performed at the time of the shipping, or at the end of the component replacement or repair. Referring to FIG. 6, in the setting mode in the operation S 20 , the controller  36  first controls the driving of the scanning unit  20  to scan the white panel  26  in operation S 31 , and extracts a quantity of light of the white value in operation S 32 . As shown in FIG. 7, the light quantity of the white value obtained from the scanned white panel is measured and extracted by the CCD sensor  31  by a predetermined voltage in the available pixels, respectively. According to the light quantity of the white value, the controller  36  determines a predetermined reference value R. The reference value R is for determining the appropriateness of the light quantity, and is programmable in consideration of the various types of lamps  21  and performance of the amplifier  32 . 
     Next, the determined reference value R is stored in the storage unit  34  in operation S 34 . Further, the controller  36  calculates an initial average A of light quantity from the light quantity of the extracted white value in operation S 35 . The initial average value A is obtained with respect to the entire area of the available pixels of the white panel  26 . The initial average value A is stored in the storage unit  34  in operation S 36 . 
     The controller  36  also divides the extracted white values into pixel divisions n in operation S 37 . Next, the controller  36  calculates initial divisional average values B 1 ˜Bn of the respective divisions of pixels in operation S 38 . The initial divisional values B 1 ˜Bn are stored in the storage unit  34  and set in operation S 39 . The initial divisional values B 1 ˜Bn may be an average value of a plurality of pixels disposed within each of the divisions n corresponding to each portion of the white panel  26 . 
     As described above, when the initial references of the light quantity of the lamp  21 , i.e., the reference value R, the initial average (A), and the initial divisional values (B 1 ˜Bn) are obtained and stored in the storage unit  34 , the initial setting in operation S 20  is completed. 
     With the initial references being set as described above, the devices are shipped and sold. In the home, when the user turns on the system for the first time, the initial references that are set before the shipping are initialized as stored in the storage unit  34 . 
     Accordingly, the comparison/determination of the light quantity is performed in operation S 23 ). The comparison/determination mode of operation S 23  will be described below in detail with reference to FIG.  8 . 
     In operation S 23 , first, the white panel  26  is scanned to re-extract the quantity of light of the lamp  21  and to obtain the respective measured values with which the initial reference values as set are compared. The CCD sensor  31  extracts the quantity of light of the white value of the scanned white panel  26  in operation S 42 . 
     The controller  36  calculates an average value a and a minimum value m from the extracted quantity of light of the white value. Then the controller  36  divides the extracted white value into divisions n, and calculates each light quantity of measured divisional values b 1 ˜bn for the respective pixels of the divisions n in operation S 43 ). The calculated measured values, i.e., the average value a, the minimum value m and the measured divisional values b 1 ˜bn are stored in the storage unit  34 , respectively in operation S 44 . The measured divisional values b 1 ˜bn may be a measured average value of a plurality of pixels of divisions n corresponding to the white panel  26 . 
     Next, the controller  36  compares the average value A initially set and stored in the storage unit  34  with the extracted average value a in operation S 45 . Then the controller  36  determines whether the initial and measured average values A, a are different from each other by more than 10% in operation S 46 . 
     When it is determined that the light quantities of the initial and measured average values are different from each other by more than 10%, the controller  36  performs a first checking in operation S 50  in which the controller  36  checks if there is abnormality in the lamp  21 . In the first checking operation S 50 , the controller  36  first searches the divisions to determine to which of the divisions the minimum value m falls in operation S 47 . Then it is determined whether the minimum value m of the light quantity is in the first division or in the nth division in operation S 48 . The first and nth divisions correspond to respective opposite end sides of the white panel  26 . 
     Here, as shown in FIG. 7, when the minimum value m of the measured light quantity L 2  is in the first or in the nth division, the minimum value m is compared with the reference value R of the light quantity L 1  as set in operation S 49 . 
     Next, the controller  36  determines whether the minimum value m is less than the reference R in operation S 51 . In operation S 51 , when the minimum value m is less than the reference R as shown in FIG. 7, the controller determines that the quantity of light of the lamp  21  is not enough, and displays a message urging a lamp replacement in the display device  38  in operation S 52 . That is, when the minimum value m is smaller than the reference value R, the light quantity from both ends of the lamp  21  are insufficient, which is because of blackening. When using the lamp  21  in such a condition, there are considerable distortions in the images. Accordingly, noticing the message for lamp exchange in the display  38 , the user replaces the lamp  21  with a new one by himself/herself or has the repairman do the replacement. 
     Meanwhile, when the difference between the initial and measured averages A, a compared in operation S 46  is smaller than 10%, a second checking in operation S 56  is performed. In operation S 56 , it is checked whether there is a contaminant in the optical path that includes a white panel  26  and mirrors  22  and  25   a.    
     In operation S 56 , first, the initially set averages of the respective initial divisional values B 1 ˜Bn are compared with the measured averages of the respective measured divisional values b 1 ˜bn, respectively in operation S 53 . Then it is determined whether there is any division where the difference between the initial divisional values B 1 ˜Bn and newly measured divisional values b 1 ˜bn is more than a predetermined reference, i.e., more than 10% for example in operation S 54 . In operation S 54 , when the difference of the initial and measured divisional values B 1 ˜Bn, b 1 ˜bn is more than 10% in the seventh division, for example (see FIG.  9 ), the controller  36  drives the display  38  to indicate a warning message about the contaminations in the optical path in operation S 55 . That is, as shown in FIG. 9, when the more than 10% of difference is found in the seventh division instead of the first or the nth division, it is assumed that a certain location of the white panel  26  that corresponds to the seventh division, or the mirrors  22  and  25   a  are contaminated. Accordingly, the warning message, like “WHITE PANEL, MIRROR CONTAMINATION!!” is displayed. Noticing the warning message, the user can check and clean or have the repairman clean the contaminated area. 
     Meanwhile, when there is no division where the difference if more than 10%, since it is assumed that the optical path inclusive of the lamp  21  is in a normal condition, the controller  36  performs the next step, i.e., the controller  36  maintains the standby mode and waits for a key input. 
     Further, in operation S 48 , even when it is determined that the minimum value m does not fall neither to the first division nor to the nth division, the second checking in operation S 56  can still be performed to check the contamination of the optical path. 
     Further, after displaying the message urging the lamp replacement in operation S 52 , the presence of contaminants in the optical path can still be checked by performing the second checking operation S 56 ). This is in consideration of the possibility that the lamp replacement time would coincide with the contamination of the optical path. Accordingly, by checking the need for lamp replacement together with the presence of contaminants in the optical path at one time, the user can be prepared for the possible errors of various kinds appropriately. 
     As described above, with the method of detecting an error in an image scanning device according to the present invention, it is determined whether to check a need for lamp replacement or a presence of contaminants in an optical path by comparing initially set reference values with newly measured values. 
     Accordingly, unlike the conventional way, the checking of the need for lamp replacement and the checking of the presence of contaminants in the optical path, can either be distinguishably and selectively performed, or simultaneously performed, so that the accurate error detecting and indicating is guaranteed. 
     Further, since the user appropriately deals with the error according to the indicated error message, replacing the lamp or cleaning the contaminated area, there is no possibility that the user replaces the lamp, which is still good, and accordingly, the costs can be reduced. Also, the user can maintain the machine with more convenience. 
     Although a few preferred embodiments of the present invention 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 sprit of the invention, the scope of which is defined in the claims and their equivalents.

Technology Category: 3