Apparatus and method for measuring developer contamination of a printer

Abstract: A developer contamination measuring apparatus of a printer includes a first pipe portion (41) having a first gap and a second pipe portion (42) having a second gap, a light emitting unit (150) for radiating light to the first pipe portion (41) and the second pipe portion (42), a light detecting unit detecting (70) for light reflected or transmitted from the first pipe portion and the second pipe portion to output first and second light receiving signals, respectively, and a developer contamination measuring unit (80) for controlling the light emitting unit, and calculating the degree of a contamination due to mixing of other developing materials with the developer from the first and the second light receiving signals. Thus, the degree of contamination of a developer mixed with other developing materials can be precisely calculated, and the developer can be replaced, when the calculated amount of contamination exceeds a predetermined allowable contamination level, to thereby prevent deterioration of print quality.

Description: The present invention relates to an apparatus and a method for measuring contamination of a developer of a printer, and more particularly to an apparatus and a method for measuring contamination of a developer of a printer using data obtained from the developer under various conditions. JP 01 210980 discloses a liquid concentration detector for detecting the concentration of developer in a liquid printer. Figure 1 is a schematic view of a typical liquid type color printer. Referring to Figure 1, a printer using a developer includes a reset apparatus 15, light scanning units 16, developing units 30, a drier 18, and a transfer apparatus 20, adjacent to the circulation path of a photosensitive belt 14 around a plurality of rollers 11, 12 and 13. The reset apparatus 15 includes an exposure apparatus 15a radiating beams to the photosensitive belt 14 to remove an electrostatic latent image, and an electrostatic charge unit 15b for charging the photosensitive belt 14 to a predetermined electric potential. Reference numeral 39 denotes a waste tank for collecting waste developer. The four light scanning units 16 scan information of yellow Y, magenta M, cyan C and black K, respectively, and the four developing units 30 supply developers of Y, M, C and K to the photosensitive belt 14, respectively. The developing unit 30 includes a developer supply unit 32 supplying a developer, and a developing bath 31 collecting developer dropped from the photosensitive belt 14 and resupplying the collected developer to the developer supply unit 32. The developing bath 31 includes a developing roller 36, a brush roller 37 for removing developer from the developing roller 36, a squeeze roller 34 for separating a liquid carrier which is regardless of image forming, from the developer supplied to the photosensitive belt 14 and a plate 35 for collecting the carrier flowing through the squeeze roller 34 to the developing bath 31. The developer stored in the developing bath 31, the liquid carrier (norpor; N) of the solvent in the developer supply portion 38, and a toner of a developing material or a developer of high concentration in the developer supply portion 38 can be supplied to the developing supply unit 32. The developer stored in the developer supply unit 32 is supplied between the developing roller 36 and the photosensitive belt 14 by driving a pump. During printing of a liquid type printer, the light scanning unit 16 scans light beams on the photosensitive belt 14 circulating past the reset apparatus 15. An electrostatic latent image is formed on the photosensitive belt 14 by the scanned light, and the electrostatic latent image is developed by the developer supplied from the developer supply unit 32. A color image is formed on the photosensitive belt 14 by the light scanning units 16 scanning light beams of different color information, and the developing units 30 developing an image by a developer of a corresponding color. Most of the liquid carrier of the developer supplied to the photosensitive belt 14 from the developing units 30 is returned into the developing bath 31. The photosensitive belt 14 moves past the drier 18 for removing liquid carrier remaining on the photosensitive belt 14. The color image formed on the photosensitive belt 14 by a toner of the developing material is then transferred to the transfer roller 21, having a portion thereof engaged to the photosensitive belt 14. The image on the transfer roller 21 is transferred to a sheet of paper 23 by rotation of the transfer roller 21 and a fixing roller 22, such that the sheet 23 is inserted and moved forward therebetween. Meanwhile, in the above-described printing operation, when toner attached to the photosensitive belt 14 during the development partially remains on the photosensitive belt 14 without being transferred to the sheet 23, the toner may drop into the developing bath 31 of the developing unit 30 during circulation of the photosensitive belt 14. Particularly, if black toner contaminates the developing bath 31 having yellow developer through the photosensitive belt 14, the appropriate color cannot be produced. Thus, contamination of developer caused by a developing material of one color mixing with the developing bath 31 of another color must be checked, and when the contamination exceeds an allowable range, the developer must be appropriately replaced. It is an aim of the present invention to provide an apparatus and method for measuring developer contamination of a printer capable of measuring the degree of a contamination of a developer recovered into a developing bath due to mixture of developing materials of other colours. According to the present invention there is provided a developer contamination measuring apparatus according to claim 1 appended hereto. Also according to the present invention there is provided a method for measuring developer contamination as set forth in claim 14 appended hereto. Other preferred features of the invention will be apparent from the dependent claims and the description which follows. According to one aspect of the present invention there is provided a developer contamination measuring apparatus for use in a printer, the apparatus comprising: a developer containing means in the form of a developer extracting pipe unit including a first pipe portion having a first gap of a first width and a second pipe portion having a second gap of a second width different from the first width; radiation detection means for detecting a signal radiated through the developer containing means; a measuring unit; and a light emitting unit for radiating light to the first pipe portion and the second pipe portion; wherein: the radiation detection means is a light detecting unit for detecting light reflected or transmitted from the first pipe portion and the second pipe portion to output first and second light receiving signals, respectively; and characterised in that: the measuring unit is a developer contamination measuring unit arranged to control the light emitting unit and includes a table in which the degree of contamination corresponding to difference between the first light receiving signal and the second light receiving signal is recorded to calculate the contamination due to mixing of other developing materials with the developer from a difference between the first light receiving signal and the second light receiving signal. Preferably, the light detecting unit comprises: a first light detector for detecting light reflected of transmitted from the first pipe portion; and a second light detector for detecting light reflected or transmitted from the second pipe portion. Preferably, the light detecting unit further comprises: an analog-to-digital converter for converting a signal output from the first and the second light detectors to a digital signal to output the converted 5 signal to the developer contamination measuring unit. Preferably, the developer contamination measuring apparatus comprises a switching unit selectively outputting one of input signals corresponding to received light from the first light detector and the second light detector in accordance with a selected signal from the developer contamination measuring unit. Preferably, the light emitting unit comprises: a first light emitting unit radiating light to the first pipe portion; and a second light emitting unit radiating light to the second pipe portion. Preferably, the first light emitting unit comprises: a first light source for radiating light to the first pipe portion; a third light detector for partially detecting light output from the first light source; a first light source controller for controlling the amount of emitted light of the first light source from the output signal corresponding to the light received from the third light detector; and a first light source driver controlled by the first light source controller to drive the first light source. Preferably, the second light emitting unit comprises: a second light source for radiating light to the second pipe portion; a fourth light detector for partially detecting light emitted from the second light source; a second light source controller for controlling the amount of emitted light by the second light source from the output signal corresponding to the light received from the fourth light detector; and a second light source driver for controlled by the second light source controller to drive the second light source. Preferably, information on the contamination calculated from the developer contamination measuring unit is indicated through a display. Preferably, the developer contamination measuring unit transmits a message informing a user to replace the developer to the display when the measured amount of contamination of the developer exceeds a predetermined allowable degree of contamination. Preferably, the developer contamination measuring unit drains the developer in a developer supply unit to a waste tank for collecting the waste developer, when the measured amount of contamination of the developer exceeds a predetermined allowable degree of contamination. Preferably, the developer contamination measuring unit supplies a new developer of the developer supply portion to the developing unit after the developer in the developing unit is drained to the waste tank. Preferably, the developer contamination measuring unit supplies information on the calculated amount of contamination to a computer connected through a communication interface. Preferably, the developer contamination measuring unit transmits a message informing a user to replace the developer to the computer, when the measured amount of contamination of the developer exceeds a predetermined allowable degree of contamination Preferably, the a developer contamination measuring apparatus of a printer comprises: a developer extracting pipe unit extracting a developer to measure the degree of contamination according to mixing of a developing material of other colors with respect to the developer in a developing unit supplying a developer to a photosensitive medium for partially recovering the supplied developer, including a first pipe portion having a first gap and a second pipe portion having a second gap; a light emitting unit radiating light to the first pipe portion and the second pipe portion; a light detecting unit detecting light reflected or transmitted from the first pipe portion and the second pipe portion to output first and second light receiving signals; respectively; and a developer contamination measuring unit controlling the light emitting unit, and calculating the degree of a contamination due to mixing of other developing materials with the developer from the first and the second light receiving signals. According to a second aspect of the present invention there is provided a method for measuring developer contamination of a printer including a developer extracting pipe unit for extracting a test developer, with a first pipe portion having a first gap, and a second pipe portion having a second gap; a light emitting unit for radiating light to the first and the second pipe portions; light detecting unit for detecting light reflected or transmitted from the first and the second pipe portions to output first and second light receiving signals, respectively; wherein the printer is characterised by comprising a developer contamination measuring unit for controlling the light emitting unit, and calculating the degree of contamination due to mixing of other developing materials into the developer from the first and the second light receiving signals output from the light detecting unit, and the method is characterised by the steps of: (a) obtaining a difference between the first light receiving signal and the second light receiving signal; and (b) finding the degree of contamination corresponding to the difference with reference to a table in which the degree of contamination corresponding to the difference between the first light receiving signal and the second light receiving signal are recorded to calculate the degree of contamination with respect to the mixing of other developing materials with the developer For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which: Figure 1 shows a typical liquid type color printer; Figure 2 shows a developer contamination measuring unit of a printer according to an embodiment of the present invention; Figure 3 is a schematic view showing the principle of generating a difference in the amounts of transmitted light in accordance with the difference in gaps of the developer extracting unit of Figure 2 with respect to the same developer; Figure 4A is a graph of an example of an output voltage of a light detector corresponding to the transmitted light of a first pipe portion according to the concentration of a pure developer with respect to a difference in contamination of the developer; Figure 4B is a graph of an example of an output voltage of a light detector corresponding to the transmitted light of a second pipe portion according to the same concentration as that of Figure 4A; Figure 4C is a graph of a difference in output voltages with respect to the concentration of the developer of Figures 4A and 4B according to the difference in contamination of the developer; Figure 5A is a graph of an output voltage corresponding to the transmitted light of the first pipe portion having a gap of 6mm with respect to the concentration of a yellow developer according to the difference in contamination of the developer; Figure 5B is a graph of an output voltage corresponding to the transmitted light of the second pipe having a gap of 1mm with respect to the concentration of a yellow developer according to the difference in contamination of the developer; Figure 6 is a circuit diagram of an internal circuit of a light detecting unit for generating an output voltage corresponding to the transmitted light of Figures 5A and 5B; and Figure 7 is a diagram of an apparatus for measuring contamination of a developer of a printer according to another embodiment of the present invention. In Figure 2, elements having the same function as those of Figure 1 are represented by like reference numerals. Referring to Figure 2, an apparatus for measuring the contamination of a developer includes a developer extracting pipe unit 40, a light emitting unit 50, a light detecting unit 70 and a developer contamination measuring unit 80. The developer extracting pipe unit 40 is provided on a developer supply pipe in which a developer supply unit 32 having a developer to be supplied to a photosensitive belt 14 is connected to a developing bath 31, and has a first pipe portion 41 and a second pipe portion 42 which are extended by gaps t1 and t2, respectively. Reference numeral 43 denotes a valve. The first gap t1 of the first pipe portion 41 and the second gap t2 of the second pipe portion 42 are determined such that the precision in measuring the contamination of an objective developer 33 is increased. The developer extracting pipe unit 40 may be provided in the developing bath 31 or the developer supply unit 32. The light detecting unit 70 includes a first light detector 71 detecting light transmitted through the first pipe portion 41 to output a signal corresponding to the received light, a second light detector 72 detecting light transmitted through the second pipe portion 42 to output a signal corresponding to the received light, a switching portion 73 selectively outputting a signal input from the first light detector 71 and the second light detector 72 in accordance with a selection signal of a developer contamination measuring unit 80, and an analog-to-digital converter 74 converting an analog signal output from the switching portion 73 into a digital signal to output the converted signal. The light emitting unit 50 includes a first light emitter 51 radiating light to the first pipe portion 41, and a second light emitter 56 radiating light to the second pipe portion 42. The first light emitter 51 includes a first light source 52 radiating light to the first pipe portion 41, a third light detector 53 detecting part of the light emitted from the first light source 52 to constantly power the light emitted from the first light source 52, a first light source controller 54 controlling the amount of light emitted from the first light source 52 in accordance with an output signal corresponding to the light received from the third light detector 53 and a first light source driving portion 55 controlled by the first light source controller 54 to drive the first light source 52. The second light emitter 56 includes a second light source 57 radiating light to the second pipe portion 42, a fourth light detector 58 detecting part of the light emitted from the second light source 57 to constantly power the light emitted from the second light source 57, a second light source controller 59 controlling the amount of light emitted from the second light source 57 in accordance with a signal output corresponding to the light received from the fourth light detector 57 and a second light source driving portion 60 controlled by the second light source controller 59 to drive the second light source 57. The developer contamination measuring unit 80 controls the first light source controller 54 and the second light controller 59, outputs a selection signal to the switching portion 73, and calculates the amount of contamination of the developer 33 using first and second light receiving signals corresponding to the received light of the first and the second light detectors 71 and 72 through the analog-to-digital converter 74. The concentration and amount of contamination in the developer 33 stored in the developer supply unit 32 are changed by mixing ratio of a solvent and/or a developer supplied from the developer supply portion (see 38 of Figure 1) and the developer supplied from the developer bath 31. Thus, when a predetermined amount of light is radiated to the developer in the developer extracting pipe unit 40, the amount of light transmitted through the developer is changed in accordance with the concentration and the amount of contamination of the developer. The concentration of the developer and amount of the contamination of the developer are changed during use by consumption of the supplied toner and evaporation of the liquid carrier even when in the case of no developer supply portion 38 (see Figure 1). Thus, the amount of contamination due to mixing of another developing material cannot be precisely measured by light receiving information obtained by irradiating light to the pipe where the developer is filled, and detecting the amount of light transmitted through or reflected from the radiated pipe. Thus, according to the present invention, first and second light receiving signals obtained from the developer in the first pipe portion 41 and the second pipe portion 42 are used to accurately calculate the amount of contamination. Importantly, the first pipe 41 is of different thickness than the second pipe 42. Referring to Figure 3 showing the case in which 20% of a developer of another color is mixed with the developer, in an area of the developer (hatched portion) of the other color projected to a cross section vertical to the optical transmission proceeding direction when light is irradiated in the direction of the arrow, the first pipe portion 41 having a relatively wider gap t1 has the other developer of a contamination material occupying all of the cross-section, while the second pipe portion 42 having a relatively narrower gap t2 has the other developer of a contamination material occupying part of the cross section. When an equal amount of light is irradiated to the first pipe portion 41 and the second pipe portion 42 with respect to the developer contaminated by the above characteristic, the amounts of transmitted light are different, so that the first and the second output light receiving signals are different. Thus, a change in the amount of transmitted light due to a change in the concentration of the pure toner or a change in the transmitted light due to mixing of other developing material can be estimated from the first light receiving signal value. When the concentration of pure toner estimated from the first light receiving signal matches the concentration of the pure toner estimated from the second light receiving signal, it can be understood that the concentration of the pure toner of the developer has changed. However, when the concentration of pure toner estimated from the first light receiving signal is different from that of the pure toner estimated from the second light receiving signal, it can be understood that the amount of light transmitted due to mixing of the contamination material is changed. From the above principle, the developer contamination measuring unit 80 includes a table in which concentrations of a pure toner and the degree of concentration corresponding to values of the first and second light receiving signals are recorded, and calculates the degree of contamination with reference to the table. To easily calculate the degree of contamination, preferably, the first gap t1 and the second gap t2 are appropriately selected such that the difference between the first and the second light receiving signals is a single value with respect to a change in concentration of the pure toner and a change due to contamination within the predetermined measurement range. Then, the contamination value and the concentration value of the pure developer corresponding to a difference between the first light receiving signal and the second light receiving signal are empirically obtained and the obtained values are recorded in a table 81 of a memory of the developer contamination measuring unit 80, and the developer contamination measuring unit 80 obtains a difference value between the received first light receiving signal and the received second light receiving signal, and calculates the contamination value corresponding to the difference with reference table of the light receiving difference and contamination value. Hereinafter, a process of calculating the difference between the first light receiving signal and the second light receiving signal, and the contamination value from the difference will be described. First and second gaps t1 and t2 having a single value within the predetermined contamination measurement range in which a difference between the first light receiving signal and the second light receiving signal is predetermined with respect to a change in concentration of the pure toner and a change due to contamination are calculated by experiments. For instance, in arbitrarily selected first and second gaps t1 and t2, the amount of received light of the first pipe portion 41 and the second pipe portion 42 in accordance with contamination of other developing materials with respect to a change in concentration of a pure toner, i.e., a first output voltage v1 and a second output voltage v2 are obtained, with contamination per interval of 0.1%, are shown in Figures 4A and 4B, and a difference value between the output voltages v1 and v2, i.e., (v1-v2) is shown in Figure 4C. Referring to Figure 4C, the concentration and the amount of contamination corresponding to the difference in output voltages V1 and V2 have a single value. Thus, when the result with respect to the arbitrarily selected gaps t1 and t2 is obtained as shown in Figure 4C, the gaps t1 and t2 are adopted to the first pipe portion 41 and the second pipe portion 42. When the gaps t1 and t2 are determined, information as shown in Figure 4C, i.e., data with respect to the concentration and the amount of contamination of the pure developer corresponding to the difference (v1 - v2) in output voltages corresponding to a difference between the first light receiving signal and the second light receiving signal is recorded in the table 81 in the developer contamination measuring unit 80. After the above described process is completed, the developer contamination can be measured. That is, the developer contamination measuring unit 80 obtains the difference between the first light receiving signal and the second light receiving signal, and calculates the contamination corresponding to the difference using the table 81. Figures 5A and 5B show first and second output voltages v1 and v2 corresponding to the light transmitted through the first pipe portion 41 and the second pipe portion 42 in the case in which a developer containing a yellow pure toner used for a liquid printer is mixed with contaminants of a black toner of 0%, 0.1%, 0.2%, 0.3%, 0.4% and 0.5% . The first gap t1 of the first pipe portion 41 is 6mm, and the second gap t2 is 1mm. Here, as shown in Figure 6, internal circuits of the light detectors 71 and 72 further include inversion circuits 71c and 72c as well as light receiving units 71b and 72b outputting a voltage signal proportional to an output current I pd corresponding to the amount of received light of the light receiving members 71a and 72a. Thus, voltage signals obtained by inverting an output voltage I pd x R 1 corresponding to the received light of the light receiving units 71b and 72b through inversion circuits 71c and 72c are output to the switching unit 73 as first and second light receiving signals. A reference voltage Vref of the inversion circuits 71c and 72c is appropriately determined with respect to the sensitivity of each of the light receiving units 71b and 72b such that a deviation of the light receiving sensitivities between the light receiving units 71b and 72b is reduced. Output voltages of the inversion circuits 71c and 72c are shown as output voltages of Figures 5A and 5B. The inversion circuits 71c and 72c are for increasing the output voltages in accordance with an increase in the amount of contamination. However, when the output signals of the light receiving units 71b and 72b are output as the first and the second light receiving signals without employing the inversion circuits 71c and 72c, the output voltage is lowered according to the increase in the contamination, which are shown in Figures 4A and 4B. The contamination values corresponding to the difference (v1-v2) of the output voltages corresponding to the light receiving signals obtained by employing a circuit of Figure 6 is shown in Figure 5C. When the concentration range of the pure developer satisfying the printing conditions is 2.4 to 3.4%, and a predetermined allowable contamination value is 0.5%, the contamination value corresponding to the difference between the light receiving signals has a single value within an error range of 0.1% and the above condition. Also, when the concentration of the pure developer in the developing bath 31 is within 2.4 ~ 3.4%, the resultant information of Figure 5C and the gaps t1 and t2 adapted to the information can be adapted to the apparatus for measuring developer contamination. Meanwhile, when the concentration range and the predetermined allowable contamination range of the pure developer are higher than the above-described range, the gaps of the first and the second pipe portions 41 and 42 having a signal difference between the light receiving signals with respect to the amount of contamination and the concentration of the pure toner must be obtained by experiments. Also, the gaps t1 and t2 of the first pipe portion 41 and the second pipe portion 42 can be adapted to any cases in which the difference between the first and the second light receiving signals has a single value with respect to the amount of contamination and concentration of the pure developer within the allowable range of the concentration of the pure developer and the predetermined contamination satisfying the printing conditions. When the amount of contamination of the developer is calculated by the above method, the developer contamination measuring unit 80 outputs information of the calculated contamination to a display 100 outside the printer body. When the display 100 is directly connected to the developer contamination measuring apparatus (denoted by dotted lines), the contamination information is directly output to the display 100, and when the display 100 is controlled by a main controller 90 controlling the total printer, the contamination information is transferred to the display 100 through the main controller 90. It is also preferable that the contamination information is transferred to a personal computer 110 connected through a communication interface through the main controller 90. When the contamination with respect to the developer is outside the allowable range, the developer contamination measuring unit 80 transfers a message requiring replacement of the developer to the display 100 and/or the computer 110. When contamination of the developer exceeds the allowable contamination value, the developer contamination measuring unit 80 drains the developer 33 in the developer supply unit 32 to the waste tank 39 for collecting waste developer. Then, new developer to be used for printing is supplied into the developer supply unit 32 from the developer supply portion 38 (see Figure 1). The main controller 90 receives print data from the computer 110 and processes the received printing data as an image data corresponding to a print engine 120 to output the processed image data to the print engine 120. The print engine 120 includes a reset apparatus, a developing unit, a light scanning unit, a drier, a transfer apparatus and a paper supply unit (not shown) (see Figure 1). Elements in Figure 7 that are the same elements as those of Figure 2 are denoted by like reference numerals. Referring to Figure 7, the developer contamination measuring apparatus includes a light emitting unit 150, a light detecting unit 70 and a developer contamination measuring unit 80. The light emitting unit 150 includes a light source 152, a light detector 153, a light source controller 154 and a light source driving unit 154. A central axis of the output light of one light source 152 is arranged facing a boundary region between the first pipe portion 41 and the second pipe portion 42 such that light is irradiated on the first pipe portion 41 and the second pipe portion 42, which is different from the developer contamination measuring apparatus of Figure 2. The light detector 153 partially detects light output from the light source 152 to output a signal corresponding to the received light, in order to monitor the bright output. The light source controller 154 controls the amount of light emitted from the light source 152 according to the feedback signal output of the light detector 153 corresponding to the received light, and the light source driving unit 155 is controlled by the light source controller 154 to drive the light source 152. The developer contamination measuring unit 80 controls the light source controller 154. The developer contamination measuring apparatus can reduce the number of elements of the light emitting unit 150.

Claims: A developer contamination measuring apparatus for use in a printer, the apparatus comprising: a developer containing means in the form of a developer extracting pipe unit (40) including a first pipe portion (41) having a first gap of a first width and a second pipe portion (42) having a second gap of a second width different from the first width; radiation detection means (70) for detecting a signal radiated through the developer containing means; a measuring unit (80); and a light emitting unit (50) for radiating light to the first pipe portion (41) and the second pipe portion (42); wherein: the radiation detection means (70) is a light detecting unit (70) for detecting light reflected or transmitted from the first pipe portion (41) and the second pipe portion (42) to output first and second light receiving signals, respectively; and characterised in that : the measuring unit (80) is a developer contamination measuring unit (80) arranged to control the light emitting unit (50) and includes a table (81) in which the degree of contamination corresponding to difference between the first light receiving signal and the second light receiving signal is recorded to calculate the contamination due to mixing of other developing materials with the developer from a difference between the first light receiving signal and the second light receiving signal. The apparatus of claim 1, wherein the light detecting unit (70) comprises: a first light detector (71) for detecting light reflected or transmitted from the first pipe portion (41); and a second light detector (72) for detecting light reflected or transmitted from the second pipe portion (42). The developer contamination measuring apparatus of any of claims 1 or 2, wherein the light detecting unit further comprises: an analog-to-digital converter (74) for converting a signal output from the first and the second light detectors (71,72) to a digital signal to output the converted signal to the developer contamination measuring unit. The developer contamination measuring apparatus of any of claims 1, 2 or 3 further comprising a switching unit (73) selectively outputting one of input signals corresponding to received light from the first light detector (71) and the second light detector (72) in accordance with a selected signal from the developer contamination measuring unit (80). The developer contamination measuring apparatus of any of claims 1 to 4, wherein the light emitting unit (50) comprises: a first light emitting unit (51) for radiating light to the first pipe portion (41); and a second light emitting unit (56) for radiating light to the second pipe portion (42). The developer contamination measuring apparatus of claim 5, wherein the first light emitting unit (51) comprises: a first light source (52) for radiating light to the first pipe portion (41); a third light detector (53) for partially detecting light output from the first light source; a first light source controller (54) for controlling the amount of emitted light of the first light source from the output signal corresponding to the light received from the third light detector; and a first light source driver (55) controlled by the first light source controller to drive the first light source. The developer contamination measuring apparatus of claims 5 or 6, wherein the second light emitting unit (56) comprises: a second light source (57) for radiating light to the second pipe portion; a fourth light detector (58) for partially detecting light emitted from the second light source; a second light source controller (59) for controlling the amount of emitted light by the second light source from the output signal corresponding to the light received from the fourth light detector; and a second light source driver (60) controlled by the second light source controller to drive the second light source. The developer contamination measuring apparatus of any of claims 1 to 7, wherein information on the contamination calculated from the developer contamination measuring unit (80) is indicated through a display (100). The developer contamination measuring apparatus of claim 8, wherein the developer contamination measuring unit (80) transmits a message informing a user to replace the developer to the display (100) when the measured amount of contamination of the developer exceeds a predetermined allowable degree of contamination. The developer contamination measuring apparatus of any of claims 1 to 9, wherein the developer contamination measuring unit (80) drains the developer in a developer supply unit (32) to a waste tank for collecting the waste developer, when the measured amount of contamination of the developer exceeds a predetermined allowable degree of contamination. The developer contamination measuring apparatus of claim 10, wherein the developer supply portion (38) supplies a new developer to the developer supply unit (32) after the developer in the developing unit is drained to the waste tank. The developer contamination measuring apparatus of any of claims 1 to 11, wherein the developer contamination measuring unit (80) supplies information on the calculated amount of contamination to a computer (100) connected through a communication interface (90). The developer contamination measuring apparatus of claim 12, wherein the developer contamination measuring unit (80) transmits a message informing a user to replace the developer to the computer (100), when the measured amount of contamination of the developer exceeds a predetermined allowable degree of contamination. A method for measuring developer contamination of a printer including a developer extracting pipe unit (40) for extracting a test developer, with a first pipe portion (41) having a first gap, and a second pipe portion (42) having a second gap; a light emitting unit (50) for radiating light to the first and the second pipe portions; a light detecting unit (70) for detecting light reflected or transmitted from the first and the second pipe portions to output first and second light receiving signals, respectively wherein the printer is characterised by comprising a developer contamination measuring unit (80) for controlling the light emitting unit, and calculating the degree of contamination due to mixing of other developing materials into the developer from the first and the second light receiving signals output from the light detecting unit, and the method is characterised by the steps of: (a) obtaining a difference between the first light receiving signal and the second light receiving signal; and (b) finding the degree of contamination corresponding to the difference with reference to a table in which the degree of contamination corresponding to the difference between the first light receiving signal and the second light receiving signal are recorded to calculate the degree of contamination with respect to the mixing of other developing materials with the developer.

Inventors: EOM YOON-SEOP, LEE WON-HYUNG, YOO YONG-BAEK, EOM, YOON-SEOP, LEE, WON-HYUNG, YOO, YONG-BAEK
Applicants: SAMSUNG ELECTRONICS CO LTD, SAMSUNG ELECTRONICS CO., LTD.
Application year: 1999
Main classification: G03G15
IPC codes: G03G15, G03G21, G01N21