Patent Publication Number: US-6912364-B2

Title: Consumable product unit, consumable product replacement sensing system and method thereof

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of Korean Application No. 2002-41368, filed Jul. 15, 2002 and Korean Application No.  2003-43998 , filed Jun. 30, 2003, in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a consumable product unit, a consumable product replacement sensing system and a method thereof, and more particularly, to a consumable product unit, a consumable product replacement sensing system and a method thereof, for recognizing whether or not a new consumable product unit is mounted in a system, as a replacement, and determining whether or not the new consumable product unit is one to use in the system, both of which by using a single circuit. 
   2. Description of the Related Art 
   Generally, a photocopier, a printer, a facsimile machine, and a multi-function machine having multi-functions of the photocopier, the printer, and the facsimile machine are types of electrophotograph printing apparatuses. Such a printing apparatus forms an image such that the printing apparatus provides a solid type developer, such as a toner, to a photosensitive medium where an electrostatic latent image forms or the printing apparatus jets a liquid type developer onto the photosensitive medium, and prints an image corresponding to the electrostatic latent image on a paper passing through rollers rotating and in contact with the photosensitive medium. 
   Consumable products such as a developer or a photosensitive belt of the printing apparatus are consumed or wear out as a result of a continuous use thereof. Accordingly, the consumable products, such as the developer and photosensitive belt are required to be replaced with new ones at proper times. For a replacement of the consumable products, a conventional printing apparatus comprises separate determination circuits to determine whether a newly replaced consumable product is a new consumable product or a used consumable product and to determine whether or not the consumable product is usable in the printing apparatus. 
   Therefore, the conventional printing apparatus requires an intermediate path circuit having a plurality of ports to connect with the respective determination circuits to an engine control unit. Since the intermediate path circuit is fabricated by an application-specific integrated circuit (ASIC) to have the plurality of ports, a problem of increased fabrication costs exists. 
   SUMMARY OF THE INVENTION 
   The present invention solves the above problem in the conventional art. Accordingly, an aspect is to provide a consumable product unit, a consumable product replacement sensing system and a method thereof to determine whether a consumable product unit is mounted in a system, as a replacement, and whether the consumable product unit is usable in the system, both of which are determined by using a single circuit. 
   Additional aspects and/or advantages 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/or other aspects are achieved by providing a consumable product replacement sensing system including a consumable product unit to determine whether a consumable product is new and determine a type of the consumable product and a consumable product replacement sensing apparatus, where the consumable product unit is mounted, to determine whether the consumable product is new and to determine the type of the consumable product. 
   Further, the consumable product unit comprises a first determination element determining whether a replaced consumable product is a new consumable product, a second determination element determining a type of the replaced consumable product, a first connection terminal connected to a first end of the first determination element, a second connection terminal connected to a first end of the second determination element, and a third connection terminal commonly connected to second ends of the first and the second determination elements. 
   Further, the first determination element is a first fusible resistor having a predetermined first resistance value and melts to disconnect the first and third connection terminals when an over-current is supplied. 
   Further, the second determination element is a second resistor having a predetermined second resistance value. The second resistance value is higher than the first resistance value and varies according to a manufacturer of the consumable product. 
   Further, the consumable product replacement sensing apparatus comprises fourth through sixth connection terminals electrically and respectively connected to the first through the third connection terminals, a new product determining signal generating unit generating a level of electrical potential corresponding to at least one of the first and the second determination elements connected to the consumable product replacement sensing apparatus through the fourth and the fifth connection terminals to determine whether the consumable product unit is a new consumable product, an over-current supplying unit intermitting a current-flow path continuing from the fourth connection terminal through the first determination element and the sixth connection terminal by supplying an over-current to disconnect the first determination element, (i.e., disconnect the current-flow path between the first and third connection terminals) and an engine control unit controlling the over-current supplying unit to disconnect the first determination element if the consumable product is determined to be new by the level of electrical potential generated at the new product determining signal generating unit, the engine control unit determining a type of the consumable product by the level of electrical potential corresponding to the second determination element. 
   The engine control unit may determine that the consumable product is a new consumable product if the level of electrical potential outputted from the new product determining signal generating unit is a first electrical potential level corresponding to the first and the second determination elements, and may determine that the consumable product is a used consumable product if the level of electrical potential outputted from the new product determining signal generating unit is a second electrical potential level corresponding to the second determination element. The first electrical potential level may be lower than a reference level, and the second electrical potential level may exceed the reference value. 
   Further, the level of electrical potential to determine whether the consumable product unit is new and the level of electrical potential corresponding to the second determination element are inputted from the new product determining signal generating unit to the engine control unit through a shared port. 
   More specifically, the new product determining signal generating unit comprises a first power source, a third resistor having a first end connected to the first power source and a second end connected to the engine control unit and the fifth connection terminal, and a diode disposed between the fourth and fifth connection terminals to prevent an electric current of the fourth connection terminal from flowing into the fifth connection terminal. 
   Further, the over-current supplying unit comprises a second power source, and a switching element to connect or to disconnect the second power source to or from the fifth connection terminal according to a control signal of the engine control unit. 
   The consumable product may be a cartridge containing one or more predetermined color developers, the consumable product unit provided with the consumable product may be a developing device that develops an image by using the one or more color developers supplied from the consumable product, and the consumable product replacement sensing apparatus may be provided in an image forming apparatus that forms the image developed by the developing device on a paper. 
   Further, the above and/or other aspects are achieved by providing a consumable product replacement sensing method comprising mounting a consumable product unit in a consumable product replacement sensing apparatus, the consumable product unit determining whether a consumable product is a new consumable product and determining a manufacturer of the consumable product, when the consumable product unit is mounted, and determining whether the consumable product is a consumable product to use in the consumable product replacement sensing apparatus. 
   More specifically, the determining of whether the consumable product is the new consumable product comprises respectively and electrically connecting first through third connection terminals to fourth through sixth connection terminals provided in the consumable product replacement sensing apparatus, wherein the first connection terminal is connected to a first end of a first determination element to determine whether the consumable product is the new consumable product, the second connection terminal is connected to a first end of a second determination element to determine whether the consumable product is usable, and the third connection terminal is commonly connected to second ends of the first and the second determination elements; generating a level of electrical potential corresponding to at least one of the first and second determination elements connected to the consumable product replacement sensing apparatus through the fourth and fifth connection terminals; determining whether the consumable product is the new consumable product by the level of electrical potential; supplying an over-current to the first determination element to disconnect the first determination element when the consumable product is determined to be new; and determining whether the consumable product is usable by the level of electrical potential corresponding to the second determination element. The first through the third connection terminals are provided in the consumable product unit. 
   The determining of whether the consumable product is the new consumable product determines that the consumable product is the new consumable product if the level of electrical potential is a first electrical potential level corresponding to the first determination element, and determines that the consumable product is a used consumable product if the level of electrical potential is a second electrical potential level corresponding to the second determination element. The first electrical potential level is lower than a reference level. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the preferred embodiment, taken in conjunction with the accompanying drawings in which: 
       FIG. 1  is a circuit diagram showing a consumable product replacement sensing system according to an embodiment of the present invention; 
       FIG. 2  is a flow chart showing a method of sensing a consumable product replacement according to the apparatus of  FIG. 1 ; and 
       FIG. 3  is a perspective view schematically showing an image forming apparatus having the consumable product replacement sensing system of FIG.  1 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Reference will now be made in detail to the present preferred embodiment of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiment is described below in order to explain the present invention by referring to the figures. 
     FIG. 1  is a circuit diagram showing a consumable product replacement sensing system according to an embodiment of the present invention. 
   Referring to  FIG. 1 , a consumable product replacement sensing system comprises a consumable product unit  10  and a consumable product replacement sensing apparatus  100 . 
   The consumable product unit  10  is replaceably mounted on the consumable product replacement sensing apparatus  100  and is replaced with a new consumable product unit when a consumable product  12  provided in the consumable product unit  10  is completely consumed. By way of example, this embodiment uses a cartridge containing one or more color developers as the consumable product  12 , and a developing device as the consumable product unit  10 , which develops an image by utilizing the one or more color developers supplied from the consumable product  12 . The consumable product replacement sensing apparatus  100  determines whether or not the consumable product unit  10  and/or the consumable product  12  are new and usable. 
   That is, the consumable product  12  is, for example, a toner, ink, a developer or a photosensitive belt, which is consumed as a result of a continuous use thereof, and the consumable product unit  10  is a developing device including a developing roller (not shown) and a developer supplying roller (not shown). The consumable product replacement sensing apparatus  100  is mountable in an image forming apparatus  300  (see  FIG. 3 ) to form an image developed by the consumable product unit  10  on a paper. 
   The consumable product unit  10  has the consumable product  12 , a first determination element R F , a second determination element R OEM , and a first connection terminal unit  14 . 
   The consumable product  12 , which is a cartridge in this embodiment by way of example, contains a yellow developer, a magenta developer, a cyan developer and a black developer. The consumable product  12  may have additional color developers. If the image forming apparatus  300  (see  FIG. 3 ) employing the consumable product replacement sensing apparatus  100  is only a one-color device (i.e., is mono type), the consumable product  12  may contain only the black developer. 
   The first determination element RF determines whether or not replacement consumable product unit  10  and/or a replacement consumable product  12  included therewith are new. The first determination element R F  uses a fusible resistor having a predetermined first resistance value (e.g. in a range of about 50 Ω). The fusible resistor melts to disconnect from at least one of first and third connection terminals  14 a and  14 c when an over-current condition causes an over-current to flow therein. 
   The second determination element R OEM  determines whether or not the consumable product unit  10  and/or the consumable product  12  included therewith are useable in the consumable product replacement sensing apparatus  100 . The second determination element R OEM  is an OEM resistor to recognize/determine an attachment of an Original Equipment Manufacturer (hereinafter, referred to as “OEM”). 
   The second determination element R OEM , which has a second resistance value differing from that of the first resistance value and varies according to a manufacturer and a type of the consumable product  12 . Accordingly, the consumable product replacement sensing apparatus  100  determines whether or not the consumable product unit  10  and/or the consumable product  12  included therewith are useable in the consumable product replacement sensing apparatus  100 , based on a resistance value of the second determination element R OEM . The second resistance value may be in a range of approximately 7 kΩ and varies according to the manufacturer and the type of the consumable product  12 . 
   The consumable product unit  10  is provided with the first connection terminal unit  14  disposed at an end of the consumable product unit  10  to electrically connect the consumable product unit  10  and the consumable product replacement sensing apparatus  100 . The first connection terminal unit  14  has a first connection terminal  14   a  connected to a first end of the first determination element R F , a second connection terminal  14   b  connected to a first end of the second determination element R OEM  and a third connection terminal  14   c  commonly connected to second ends of the first and second determination elements R F  and R OEM . 
   Further, the consumable product replacement sensing apparatus  100  provided in the image forming apparatus  300  (see  FIG. 3 ) comprises a second connection terminal unit  110 , a new product determining signal generating unit  120 , an over-current supplying unit  130 , an ASIC  140 , an engine control unit  150  and a storage unit  160 . 
   The consumable product replacement sensing apparatus  100  determines whether or not the replaced/mounted consumable product unit  10  and/or the replaced/mounted consumable product  12  included therewith are new and determines whether or not the replaced/mounted consumable product unit  10  and/or the replaced mounted consumable product  12  included therewith are useable in the consumable product replacement sensing apparatus  100 . Since the determining operations of the consumable product unit  10  are performed in the same manner as that of consumable product  12 , hereinafter, descriptions are provided only with regard to the consumable product unit  10  for convenience of explanation, but would additionally apply to the consumable product  10 . 
   The second terminal unit  110  has forth through sixth connection terminals  110   a ,  110   b  and  110   c . The fourth through the sixth connection terminals  110   a ,  110   b  and  110   c  are respectively and electrically connected with the first through the third connection terminals  14   a ,  14   b  and  14   c.    
   The new product determining signal generating unit  120  has a first power source V CC1 , a pull-up resistor R pull-up  and a diode  122 . 
   The pull-up resistor R pull-up  has a first end serially connected to the first power source V CC1  and a second end connected with the ASIC and the fifth connection terminal  110   b . The diode  122  is disposed between the fourth connection terminal  110   a  and the fifth connection terminal  110   b  to prevent an electric current of the fourth connection terminal  110   a  from flowing to the fifth connection terminal  110   b.    
   When the first connection terminal unit  14  of the consumable product unit  10  is connected to the second connection terminal unit  110  of the consumable product replacement sensing apparatus  100  so that the consumable product unit  10  is mounted on the consumable product replacement sensing apparatus  100 , the new product determining signal generating unit  120  generates a level of electrical potential S 1  that corresponds to an effective resistance value of the consumable product unit  10  connected to the consumable product replacement sensing apparatus  100  through the fourth and the fifth connection terminals  110   a  and  110   b.    
   That is, the new product determining signal generating unit  120  generates a level of electrical potential S 1  that corresponds to at least one of the first and the second determination elements R F  and R OEM . The engine control unit  150  determines whether the consumable product unit  10  and/or the consumable product  12  included therewith are new, based on the level of electrical potential S 1 . 
   More specifically, when the consumable product unit  10  is mounted on the consumable product replacement sensing apparatus  100 , the first power source V CC1  supplies a predetermined electric potential to the pull-up resistor R pull-up . If the consumable product unit  10  is the new consumable product unit, the level of electrical potential S 1  at a node A has a ‘low’ value due to a current path that forms among the pull-up resistor R pull-up , the node A and the sixth connection terminal  110   c , which is grounded. 
   That is, if the consumable product unit  10  is the new consumable product unit, the effective resistance value has a parallel composite resistance value of the first and second determination elements R F  and R OEM . Accordingly, the effective resistance value provides a lowered electrical potential, and the new product determining signal generating unit  120  generates the ‘low’ level of electrical potential S 1  at node A. The level of electrical potential S 1 , which corresponds to the first and the second determination elements R F  and R OEM , has a low value if the level of electrical potential S 1  is lower than a reference level (e.g., in a range of about 2.4 volt). 
   If the consumable product unit  10  is a used consumable product unit, the first determination element R F  of the fusible resistor melts and is disconnected from at least one of the first and third connection terminals  14   a  and  14   c  to produce an open circuit condition such that the effective resistance value has a resistance value of the second determination element R OEM  of an OEM resistor. Thus, the effective resistance value provides an increased electrical potential, and the new product determining signal generating unit  120  generates a level of electrical potential that corresponds to the second determination element R OEM . The level of electrical potential S 1  at the node A, which corresponds to the second determination element R OEM , has a high value, since the level of electrical potential S 1  exceeds the reference level. 
   The over-current supplying unit  130  has a second power source V CC2  and a switching element  132 . The over-current supplying unit  130  intermits a current-flowing path continuing from the fourth connection terminal  110   a  through the first determination element R F  to the sixth connection terminal  110   c . Further, the over-current supplying unit  130  supplies an over-current to disconnect the first determination element R F  from at least one of the first and third connection terminals  14   a  and  14   c.    
   The second power source V CC2  supplies a predetermined electrical potential to a first resistance element R 1  serially connected to the second power source V CC2  and a second resistance element R 2  parallel connected to the first resistance element R 1 . 
   The switching element  132  supplies the predetermined voltage supplied from the second power source V CC2  to the fourth connection terminal  110   a  or the switching element  132  blocks the predetermined voltage supplied from the second power source V CC2  to the fourth connection terminal  110   a  according to a control signal (i.e., a level of electrical potential S 2 ) of the engine control unit  150 . The switching element  132  uses a PNP type transistor that performs a switching operation by adjusting an electric current flowing between an emitter terminal of the transistor and a collector terminal of the transistor according to a voltage of a base terminal of the transistor. 
   The ASIC  140  is an intermediate path circuit to output the level of electrical potential S 1  inputted from the node A to the engine control unit  150 , and is connected to the new product determining signal generating unit  120  through a single shared port, as shown in a thick solid line in FIG.  1 . That is, the ASIC  140  is input with the level of electrical potential S 1  from the node A through the single shared port. 
   The engine control unit  150  determines whether or not the consumable product unit  10  is the new consumable product unit and whether or not the consumable product  10  is useable in the consumable product replacement sensing apparatus  100 , based on the level of electric potential S 1  generated at the new product determining signal generating unit  120 . More specifically, the engine control unit  150  determines that the consumable product unit  10  is the new consumable product unit if the level of electric potential S 1  initially generated at the new product determining signal generating unit  120  is a first electrical potential level corresponding to the first and the second determination element R F  and R OEM . Also, the engine control unit  150  controls the over-current supplying unit  130  to disconnect the first determination element R F  from, at least one of the first and third connection terminals  14   a  and  14   c . That is, the engine control unit  150  supplies the switching element  132  with the level of electric potential S 2 , which is lower than a reference level, and is delivered to the switching element  132  through a third reistance element R 3 , so that the switching element  132  switches on. When the switching element  132  switches on, the first determination element R F  is disconnected by the over-current. 
   After the disconnection of the first determination element R F , the engine control unit  150  determines whether or not the consumable product unit  10  is usable in the consumable product replacement sensing apparatus  100  by the level of electric potential S 1  subsequently generated at the new product determining signal generating unit  120 . Descriptions about this will be made in detail later with reference to FIG.  2 . 
   If the level of electric potential S 1  initially generated at the new product determining signal generating unit  120  is a second electric potential level corresponding to the second determination element R OEM , the engine control unit  150  determines that the consumable product unit  10 , as mounted, is a used consumable product unit. 
   The first electric potential level is lower than a pre-set reference level, and the second electric potential level exceeds the reference level. The reference levels are pre-set in the storage unit  160  of the consumable product replacement sensing apparatus  100  to determine whether the consumable product unit  10  is the new consumable product unit or the used consumable product unit. In the case that the resistance value of the second determination element R OEM  is determined to be within a predetermined range according to the manufacturer, the reference level has a predetermined range according to a predetermined range of the second determination element R OEM . 
   Further, the engine control unit  150  controls general operations of the consumable product replacement sensing apparatus  100  and/or the image forming apparatus  300  (see  FIG. 3 ) using the new consumable product replacement sensing apparatus  100  according to the level of electric potential S 1 . For example, when the engine control unit  150  determines that the consumable product unit  10  is the used consumable product unit by the second potential level inputted from the ASIC  140 , the engine control unit  150  displays a message on a panel (not shown) of the image forming apparatus  300  (see FIG.  3 ), indicating that the consumable product unit  10  is unusable. 
   The storage unit  160  stores the reference level to determine whether the consumable product unit  10  is the new consumable product unit or the used consumable product unit and a comparison level of a predetermined range to determine whether or not the consumable product unit  10  is usable in the consumable product replacement sensing apparatus  100 . 
   Operations of the control engine unit  150  will be described in detail with reference to FIG.  2 . 
     FIG. 2  is a flow chart showing a method of sensing a consumable product replacement. 
   Referring to  FIGS. 1 and 2 , the consumable product unit  10  is mounted on the consumable product replacement sensing apparatus  100  used in the image forming apparatus  300  (see  FIG. 3 ) at operation S 200 . The new product determining signal generating unit  120  generates a level of electrical potential S 1  corresponding to the effective resistance value of the consumable product unit  10  (i.e., the first electric potential level). 
   The engine control unit  150  compares the first electric potential level with the reference level pre-set in the storage unit  160  of the consumable product replacement sensing apparatus  100  at operation S 210 , and determines that the consumable product unit  10  is the new consumable product unit if the first electric potential level is lower than the pre-set reference level at operation S 220 . 
   After the operation of S 220 , the engine control unit  150  supplies the switching element  132  with the level of electric potential S 2  lower than the reference level to supply an over-current to the first determination element R F  at operation S 230 . The switching element  132  switches on to allow a flow of the over-current to the first determination element R F , which results in a disconnection of the first determination element R F  at operation S 240 . 
   After the operation S 240 , the new product determining signal generating unit  120  outputs a level of electric potential S 1  corresponding to the second determination element R OEM  (i.e., the second electric potential level ) to the ASIC  140 . That is, as the first determination element R F  is disconnected from at least one of the first and third connection terminals  14   a  and  14   c  (i.e., is opened circuited), the effective resistance value of the consumable product unit  10  is determined by only a independent resistance of the second determination element R OEM . The ASIC  140  supplies the second electrical potential level to the engine control unit  150 . That is, the second electric potential level, corresponding to the second determination element R OEM , is inputted to the engine control unit  150  through the node A and the ASIC  140 . The second electric potential level corresponding to the second determination element R OEM  which has a difference resistance value than that of the first determination element R F , and varies according to a manufacturer and a type of the consumable product unit  10 . 
   After the operation S 240 , the engine control unit  150  receives the second electric potential level corresponding to the second determination element R OEM  from the new product determining signal generating unit  120  at operation S 250 . Then, the engine control unit  150  reads out the comparison level from the storage unit  160  and compares the second electrical potential level with the comparison level at operation S 260 . The comparison level has a predetermined range to determine whether or not the consumable product  10  is usable in the consumable product replacement sensing apparatus  100  and has different ranges according to the manufacture and the type of the consumable product unit  10 . 
   In the operation S 260 , if the second electric potential falls within the range of the comparison level, the engine control unit  150  determines that the consumable product unit  10  is usable in the consumable product replacement sensing apparatus  100  at operation S 270 . If the second electric potential does not fall within the range of the comparison level in the operations S 260 , the engine control unit  150  determines that the consumable product unit  10  is not usable in the consumable product replacement sensing apparatus  100 . Further, the engine control unit  150  displays a message informing that the consumable product unit  10  is not usable in the consumable product replacement sensing apparatus  100  on the panel of the consumable product replacement sensing apparatus  100 . An alarm sound may be used instead of or with the message. 
   Further, if the level of electric potential SI generated in the operation S 220  is higher than the pre-set reference level, the engine control unit  150  determines that the consumable product unit  10  is a used consumable product unit at operation S 290 . Thus, the level of electrical potential S 1  generated in the operation S 290  is the second electrical potential level corresponding to the second determination element R OEM . Further, the engine control unit  150  subsequently performs the operations S 260 -S 280  again. 
   If the second electrical potential level is not received in the operation S 250 , the first determination element R F  is not disconnected from at least one of the first and third connection terminals  14   a  and  14   c . Accordingly, generating the second electrical potential level is delayed until the first determination element R F  is disconnected from at least one of the first and third connection terminals  14   a  and  14   c.    
   The consumable product replacement sensing apparatus  100  as described above is mountable in a system using the consumable product unit  10 , for example, in the image forming apparatus  300 . The system is not limited to any one apparatus, thus the system may be used in, for example, a printer, a photocopier and a multi-function machine using a toner. 
     FIG. 3  is a perspective view schematically showing an image forming apparatus which has the consumable product replacement sensing system of FIG.  1 . 
   By way of example, a multi-color printer is used as the image forming apparatus  300 . Referring to  FIGS. 1 and 3 , the image forming apparatus  300  includes a plurality of consumable product units  10 ,  20 ,  30  and  40  each containing a different color of developer, a photosensitive drum  310  to transfer the developer formed in a predetermined image on a surface thereof to a printing paper, a mounting portion frame  320  to which the plurality of consumable product units  10 ,  20 ,  30  and  40  are removably mounted in a direction of arrow ‘x’, and a consumable product replacement sensing apparatus  100  to detect whether or not each of the consumable product units  10 ,  20 ,  30  and  40  which is electrically connectable with the mounting portion frame  320 , is connected, and further, whether or not the consumable product unit  10 ,  20 ,  30  and  40  has been replaced. 
   The plurality of consumable product units  10 ,  20 ,  30  and  40  are a part of a developing system to develop an image by using predetermined colors of developers being fed from cartridges. That is, the cartridges are ones of the consumable products  12  each of which containing a predetermined color of a respective developer therein such that the cartridges of the consumable product units  10 ,  20 ,  30  and  40  have different colors of the developers, respectively. 
   The consumable product unit  10 , being a first consumable product unit  10 , contains black developer, a second consumable product unit  20  contains a cyan developer, a third consumable product unit  30  contains a magenta developer, and a fourth consumable product unit  40  contains a yellow developer. 
   Because the consumable product units  20 ,  30  and  40  have an identical structure as that of the first consumable product unit  10 , description thereof will be omitted. One difference between the consumable product units  10 ,  20 ,  30  and  40  is that each consumable product unit  10 ,  20 ,  30  and  40  has a different resistance value at the second determination element R OEM  according to a corresponding color thereof. This is because the cartridges of the respective consumable product units  10 ,  20 ,  30  and  40  have the different colors of the developers. Accordingly, the consumable produce replacement sensing apparatus  100  determines the color of the developer based on a respective resistance value at the second determination element R OEM . 
   The consumable product unit  10 ,  20 ,  30  and  40 , the consumable product replacement sensing system and the method thereof, integrate elements to recognize whether the consumable product unit  10  is replaced with the new consumable product unit  10 ,  20 ,  30  and  40  and to determine whether the consumable product unit  10 ,  20 ,  30  and  40  is the consumable product unit to be used in the system, into a single circuit, thereby reducing a number of ASIC ports and providing a simplified circuit compared to that of the conventional art. Accordingly, a manufacturing cost of the ASIC is reducible. 
   The foregoing embodiments and/or advantages are merely exemplary and are not to be constructed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. 
   Although an embodiment of the present invention has 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 the claims and their equivalents.