Color image forming apparatus and color misalignment adjusting
Contents
1. 0136 Furthermore since the main control portion 300 performs rough adjustment of color misalignment based on the first data D1 having an interval larger than that of the second data D2 and then performs fine adjustment of color misalignment based on the second data D2 having an interval smaller than that of the first data D1 the correction of color misalignment can be precisely performed 0137 Furthermore since the first data D1 and the second data D2 are used to perform adjustment of color misalign ment based on the preset conditions rough adjustment of color misalignment using the first data D1 can be performed based ona preset condition e g at the time of initial settings where the color misalignment amount may be significant and fine adjustment of color misalignment using the second data D2 can be periodically performed based on a preset condition in ordinary use e g the time As a result since the rough adjustment of color misalignment using the first data D1 has been performed in advance misalignment in the fine adjust ment of color misalignment using the second data D2 is slight and the adjustment of color misalignment can be more precisely performed On the other hand if the adjustment of color misalignment using the second data D2 is performed under for example the conditions at the time of initial set tings since the range in which the adjustment of color mis alignment can be performed is narrow misalignme2. 0078 The image forming apparatus 100 includes a docu ment reading device 108 and an apparatus main body 110 The apparatus main body 110 is provided with an image forming portion 102 and a paper transport system 103 0079 The image forming portion 102 includes a light exposure unit 1 a plurality of development units 2 a plurality of photosensitive body units 4 an intermediate transfer belt unit 6 a pre transfer charging unit 8 a plurality of toner cartridge units 21 and a fixing unit 7 In this embodiment the light exposure unit 1 the development units 2 the photosen sitive body units 4 the intermediate transfer belt unit 6 and the toner cartridge units 21 function as a plurality of freely detachable image forming units 200 that perform different image forming operations Here it is assumed that the pho tosensitive body units 4 are units each formed by combining a unit for photosensitive operations a unit for charging and a unit for cleaning into one unit 0080 Furthermore the paper transport system 103 includes a paper feed tray 81 a manual paper feed tray 82 and a paper discharge tray 91 0081 A document placement platen 92 made of transpar ent glass on which a sheet such as a document hereinafter referred to as a document is to be placed is provided above the apparatus main body 110 and an optical unit 90 for reading a document is provided below the document place ment platen 92 Furthermore the documen
3. 0050 91 Paper discharge tray 0051 92 Document placement platen 0052 100 Image forming apparatus 0053 102 Image forming portion 0054 103 Paper transport system 0055 108 Document reading device 0056 110 Apparatus main body 0057 200 Image forming unit 0058 300 Main control portion 0059 301 Input portion 0060 302 Display portion 0061 303 Storage portion 0062 304 Image processing operation portion 0063 305 Network 0064 306 Network interface 0065 307 Telephone line 0066 308 Facsimile portion US 2013 0039680 Al 0067 309 Bus 0068 310 Sensor portion 0069 D1 First data 0070 D2 Second data 0071 P1 P2 P3 P4 Detection pattern 0072 PB Detection pattern block 0073 S Paper transport path DESCRIPTION OF THE EMBODIMENT 0074 Hereinafter an embodiment according to the present invention will be described with reference to the drawings 0075 lt Description of the Overall Configuration of the Image Forming Apparatus gt 0076 FIG 1 is a schematic cross sectional front view showing the overall configuration of an image forming appa ratus 100 according to this embodiment 0077 Theimage forming apparatus 100 shown in FIG 1 is a color image forming apparatus that forms an image using at least one color a plurality of colors or a single color on a sheet such as a recording paper hereinafter referred to as a recording paper according to image data transmitted from the outside
4. FAX via a tele phone line 307 These constituent components are connected to each other via a bus 309 such that image data signals can be transmitted and received 0105 The main control portion 300 controls the input portion 301 the display portion 302 the storage portion 303 the image processing operation portion 304 the network interface 306 the optical unit 90 the image forming portion 102 and the facsimile portion 308 For example the main control portion 300 causes the image forming portion 102 to perform a printing process image forming process based on image data received via the network interface 306 Further more the main control portion 300 causes the facsimile por tion 308 to perform a facsimile transmitting process that dials a designated destination phone number and transmits image data that is a transmission target Furthermore the main con trol portion 300 causes the optical unit 90 to perform a scan ning process that reads an image formed on a document In this manner the main control portion 300 causes these con stituent components of the image forming apparatus 100 to perform various operations based on input from the input portion 301 input from the outside via the network interface 306 input from the outside via the facsimile portion 308 and the like 0106 The image forming portion 102 is a so called imag ing engine that is controlled by the main control portion 300 and refers to a group consist
5. Patent Application Publication Feb 14 2013 Sheet 4 of 4 US 2013 0039680 A1 FIG 5 START Si Perform NO rough adjustment YES Perform ordinary S7 operation Read patterns for rough S adjustment Form pattern images S3 Continue image formation Detect pattern images S4 S5 Color misalignment NO A between colors Read patterns for fine S10 YES S6 adjustment Correct color misalignment Form pattern images Sil A Detect pattern images S12 S15 NO Perform fine adjustment Detect YES Detect color misalignment between colors Correct color misalignment END US 2013 0039680 Al COLOR IMAGE FORMING APPARATUS AND COLOR MISALIGNMENT ADJUSTING METHOD BACKGROUND OF THE INVENTION 0001 This application claims priority under 35 U S C 119 a on Patent Application No 2011 177010 filed in Japan on Aug 12 2011 the entire contents of which are herein incorporated by reference 0002 The present invention relates to a color image form ing apparatus and a color misalignment adjusting method that correct color misalignment of images using a plurality of colors 0003 Conventionally in a color image forming apparatus hereinafter referred to as an image forming apparatus an electrostatic latent image is formed by irradiating a photosen sitive body such as a photosensitive drum with laser beams modulated according to image data the electrostatic latent image formed
6. a thickness of approxi mately 100 um to 150 um 0092 Toner images are transferred from the photosensi tive drums 3 to the intermediate transfer belt 61 by means of the intermediate transfer rollers 64 that are in contact with the back face of the intermediate transfer belt 61 The intermedi ate transferrollers 64 are supplied with a high voltage transfer bias high voltage having a polarity opposite the polarity of the charged toner for transferring toner images The intermediate transfer rollers 64 are each made by forming its core with a metal e g stainless steel shaft having a diameter of 8 mm to 10 mm and covering the surface of the core with a conductive elastic material e g EPDM ethylene propy lene diene rubber or resin material such as foamed urethane The intermediate transfer rollers 64 function as transfer elec trodes that apply a high voltage uniformly to the intermediate transfer belt 61 with the conductive elastic material Although roller like transfer electrodes are used as the transfer elec trodes in this embodiment other transfer electrodes such as brush like transfer electrodes can be used 0093 As described above toner images that are made visible according to the color phases on the respective pho tosensitive drums 3 are superimposed on the intermediate transfer belt 61 When the intermediate transfer belt 61 is revolved the toner images superimposed on the intermediate transfer belt 61 are tra
7. images having different intervals as data of detection images including the plurality of detection patterns 0012 According to the present invention since the adjust ment of color misalignment is performed using at least two types of data of detection images having different intervals a plurality of adjustment choices can be provided for the adjust ment of color misalignment As a result the adjustment of color misalignment can be performed with a given level of precision depending on occasions such as those when per forming initial settings or when performing maintenance after use of the color image forming apparatus That is to say the detection can be performed with an optimal level of pre cision depending on the conditions Furthermore the amount of toner consumed can be suppressed whichever type of data of detection images is used to perform the adjustment of color misalignment In a specific embodiment of the present inven tion since a plurality of types of data of detection images are used the adjustment of color misalignment can be performed in a sequential or stepwise manner from rough adjustment to fine adjustment and the correction of color misalignment can be precisely performed 0013 Theabove described configuration may be such that the data of detection images include two types of data com posed of first data of detection images and second data of detection images having an interval smaller than that of the first da
8. intermediate transfer belt 61 will cause mixture of toner colors in subsequent processes There fore the toner that has remained on the intermediate transfer belt 61 is removed and recovered by the cleaning unit 65 Specitically the cleaning unit 65 includes a cleaning member e g acleaning blade that is in contact with the intermediate transfer belt 61 The idler roller 63 supports the intermediate transfer belt 61 from the inside back face side and the cleaning member is in contact with the intermediate transfer belt 61 so as to press the intermediate transfer belt 61 toward the idler roller 63 from the outside 0096 The pre transfer charging unit 8 in this example has a pre transfer charger PTC and is provided near the inter mediate transfer belt 61 on the upstream side of the transfer nip between the transfer roller 10 and the intermediate trans Feb 14 2013 fer belt 61 and on the downstream side of the photosensitive body units 4 in the movement direction M of the intermediate transfer belt 61 0097 Incidentally the toner images that are transferred from the photosensitive drums 3 to the intermediate transfer belt 61 include halftone areas or solid areas or include areas having different numbers of toner layers and therefore the charge level may vary from area to area Furthermore the charge level within a toner image on the intermediate transfer belt 61 after the primary transfer may vary due to exfoliation disc
9. interval of 6 3 mm three detection pattern blocks PB can be formed with respect to one revolution of the photosensitive drums 3 0113 The second data D2 of detection images is used as reference interval data for fine adjustment of color misalign ment As shown in FIG 4 the detection image are respec tively formed at portions corresponding to both sides in the width direction upper and lower sides in the drawing on the intermediate transfer belt 61 the detection patterns P1 P2 P3 and P4 are formed as rectangles having the same size and the same shape and the longitudinal direction of the patterns matches the main scanning direction According to the sec ond data D2 of the detection images having an interval of 3 8 mm five detection pattern blocks PB can be formed with respect to one revolution of the photosensitive drums 3 US 2013 0039680 Al 0114 The first data D1 and the second data D2 are differ ent from each other only in terms of the interval in the sub scanning direction and are the same in terms of the width the length in the sub scanning direction the length the length in the main scanning direction and the color arrangement order of the detection patterns of the respective colors Thus the amount of toner consumed in fine adjustment using the second data D2 is only 5 3 of the amount of toner consumed in rough adjustment using the first data D1 Accordingly it is possible to improve the detection precision wh
10. under for example the conditions at the time of initial settings since the range in which the adjustment of color misalignment can be performed is narrow misalignment between installation posi tions when installing the image forming portion such as a plurality of photosensitive body units has to be substantially eliminated Thus with the technique at the time of the present application it is difficult to perform adjustment of color mis alignment using the second data when the color misalignment amount may be significant for example at the time of initial settings 0017 In order to achieve the above described object the present invention is further directed to a color misalignment adjusting method ofa color image forming apparatus includ ing a formation step of forming a plurality of detection pat terns respectively corresponding to a plurality of colors from a plurality of photosensitive body units respectively corre sponding to the plurality of colors onto a transfer member in a sub scanning direction of the transfer member and an adjustment step of detecting intervals between detection pat terns adjacent to each other in the sub scanning direction among the plurality of detection patterns formed in the for mation step and performing adjustment of color misalign ment based on the detected intervals wherein the plurality of detection patterns have the same size and the same shape and the adjustment of color misalignment is p
11. wherein the data of detection images includes two types of data composed of first data of detection images and second data of detection images having an interval smaller than that of the first data and after the adjustment of color misalignment using the first data is performed the adjustment of color misalignment using the second data is performed 3 The color image forming apparatus according to claim 2 wherein the adjustment of color misalignment is performed based on a preset condition using the first data and the second data 4 A color misalignment adjusting method of a color image forming apparatus comprising a formation step of forming a plurality of detection patterns respectively corresponding to a plurality of colors from aplurality of photosensitive body units respectively cor responding to the plurality of colors onto a transfer member ina sub scanning direction of the transfer mem ber and an adjustment step of detecting intervals between detection patterns adjacent to each other in the sub scanning direc tion among the plurality of detection patterns formed in the formation step and performing adjustment of color misalignment based on the detected intervals wherein the plurality of detection patterns have the same size and the same shape and the adjustment of color misalignment is performed in the adjustment step using at least two types of data of detec tion images having different intervals as data of detec t
12. 2 Feb 14 2013 0124 The data actually detected in Step S12 and the sec ond data D2 are compared with each other to detect color misalignment Step S13 0125 Ifthere is color misalignment in Step S13 YES in Step S13 the optical path length is corrected according to the color misalignment amount Step S14 which corresponds to the adjustment step in the present invention and the fine adjustment of color misalignment ends thereby ending the adjustment of color misalignment 0126 Furthermore if there is no color misalignment in Step S13 NO in Step S13 the fine adjustment of color misalignment ends thereby ending the adjustment of color misalignment 0127 Furthermore if there is no request to perform initial settings of the image forming apparatus 100 for example when performing inspection in the plant or when installing the image forming apparatus 100 NO in Step S1 the ordi nary image forming operation image forming process is performed Step S7 and the image forming operation image forming process is performed based on a preset condition Step S8 The preset condition in this example may be a condition relating to the image forming process or may be a condition relating to the image forming time Specifically the preset condition may be the number of recording papers that have undergone image formation or may be the time at which image formation was performed 0128 Ifthe preset condition is not satisfie
13. 4 formed on the intermediate transfer belt 61 are detected by the sensor portions 310 the detected data and the reference interval data are compared with each other to detect color misalignment and the optical path length is corrected according to the color misalignment amount 0111 Regarding the adjustment of color misalignment using the above described adjustment means in this embodi ment data of detection images having two different intervals see FIGS 3 and 4 is stored in the storage portion 303 as reference intervals Specifically data of detection images having a reference interval of 6 3 mm as shown in FIG 3 hereinafter referred to as first data D1 and data of detec tion images having a reference interval of 3 8 mm which is smaller than that of the first data D1 as shown in FIG 4 hereinafter referred to as second data D2 are stored 0112 The first data D1 of detection images is used as reference interval data for rough adjustment of color mis alignment As shown in FIG 3 the detection images are respectively formed at portions corresponding to both sides in the width direction upper and lower sides in the drawing on the intermediate transfer belt 61 the detection patterns P1 P2 P3 and P4 are formed as rectangles having the same size and the same shape and the longitudinal direction of the patterns matches the main scanning direction According to the first data D1 of the detection images having an
14. US 20130039680A1 a2 Patent Application Publication o Pub No US 2013 0039680 A1 as United States KUMAGAT et al 43 Pub Date Feb 14 2013 54 COLOR IMAGE FORMING APPARATUS AND COLOR MISALIGNMENT ADJUSTING METHOD 76 Inventors Yuji KUMAGAI Osaka JP Norio Tomita Osaka JP Kiyoshi Sasoh Osaka JP 21 Appl No 13 554 478 22 Filed Jul 20 2012 30 Foreign Application Priority Data Aug 12 2011 JP 2011 177010 Publication Classification 51 Int Cl G03G 15 01 2006 01 START Perform rough adjustment Si NO YES Read patterns for rough S2 adjustment Form pattern images S3 Detect pattern images S4 5 Color misalignment NO between colors S6 YES Correct color misalignment 652 US Ck seins nae o Su eae as 399 301 57 ABSTRACT According to a color image forming apparatus a plurality of detection patterns respectively corresponding to a plurality of colors are formed from a plurality of photosensitive body units respectively corresponding to the plurality of colors onto a transfer member in a sub scanning direction of the transfer member intervals between detection patterns adja cent to each other in the sub scanning direction among the plurality of formed detection patterns are detected and adjustment of color misalignment is performed based on the detected intervals The plurality of detection patterns have the same s
15. an intermediate transfer belt 61 functioning as an intermediate transfer member a drive roller 62 an idler roller 63 a plurality of intermediate transfer rollers 64 and a cleaning unit 65 0089 Four intermediate transfer rollers 64 are provided respectively corresponding to colors Y M C and K The drive roller 62 supports the intermediate transfer belt 61 in a tensioned state in cooperation with the idler roller 63 and the intermediate transfer rollers 64 When the drive roller 62 is driven to rotate the intermediate transfer belt 61 is revolved in the movement direction direction indicated by arrow M in FIG 1 which causes the idler roller 63 and the intermediate transfer rollers 64 to be idly rotated 0090 The intermediate transfer rollers 64 are supplied with a transfer bias for transferring toner images formed on the photosensitive drums 3 to the intermediate transfer belt 61 0091 The intermediate transfer belt 61 is provided so as to be in contact with each of the photosensitive drums 3 Toner images of the respective colors formed on the photosensitive drums 3 are sequentially transferred to the intermediate trans fer belt 61 so as to be superimposed one after another so that a color toner image multicolor toner image can be formed on the surface of the intermediate transfer belt 61 The inter US 2013 0039680 Al mediate transfer belt 61 is for example formed in the form of an endless belt made of a film having
16. d in Step S8 NO in Step S9 the image forming operation image forming process is continuously performed Step S8 0129 Furthermore if the preset condition is satisfied in Step S8 YES in Step S9 the main control portion 300 automatically periodically or forcibly performs fine adjust ment of color misalignment YES in Step S9 and the second data D2 the patterns for fine adjustment is read from the storage portion 303 Step S10 0130 After the second data D2 is read in Step S10 the image forming portion 102 uses the photosensitive body units 4 corresponding to the four respective colors to form the detection patterns P1 P2 P3 and P4 on the intermediate transfer belt 61 based on the second data D2 and its related data reference interval etc Step S11 which corresponds to the formation step in the present invention 0131 After the detection patterns P1 P2 P3 and P4 are formed on the intermediate transfer belt 61 in Step 11 actual intervals between adjacent detection patterns P1 P2 P3 and P4 are detected by the sensor portions 310 Step 12 0132 The data actually detected in Step S12 and the sec ond data D2 are compared with each other to detect color misalignment Step S13 0133 Ifthere is color misalignment in Step S13 YES in Step S13 the optical path length is corrected according to the color misalignment amount Step S14 which corresponds to the adjustment step in the present invention and the
17. data D1 are compared with each other to detect color mis alignment Step S5 0120 If there is color misalignment in Step S5 YES in Step 5 the optical path length is corrected according to the color misalignment amount Step S6 which corresponds to the adjustment step in the present invention and the rough adjustment of color misalignment ends Next in order to perform fine adjustment using the second data D2 the second data D2 the patterns for fine adjustment is read from the storage portion 303 Step S10 0121 Furthermore if there is no color misalignment in Step S5 NO in Step S5 the rough adjustment of color misalignment ends Next in order to perform fine adjustment using the second data D2 the patterns for fine adjustment the second data D2 is read from the storage portion 303 Step S10 0122 After the second data D2 is read in Step S10 the image formingportion 102 uses the photosensitive body units 4 corresponding to the four respective colors to form the detection patterns P1 P2 P3 and P4 on the intermediate transfer belt 61 based on the second data D2 and its related data reference interval etc Step S11 which corresponds to the formation step in the present invention 0123 After the detection patterns P1 P2 P3 and P4 are formed on the intermediate transfer belt 61 in Step S11 actual intervals between adjacent detection patterns P1 P2 P3 and P4 are detected by the sensor portions 310 Step S1
18. dge of the recording paper 0101 The fixing unit 7 fixes an unfixed toner image onto the recording paper and includes the heat roller 71 and the pressure roller 72 that function as fixing rollers The heat roller 71 is heated with a heater 71a provided inside it and is kept at a predetermined fixing temperature based on a signal from a temperature detector 71b The fixing unit 7 is further provided with an external heating belt 73 for heating the heat roller 71 from the outside 0102 Inthe thus configured image forming apparatus 100 when there is a request for simplex printing on a recording paper a recording paper fed from the paper feed tray 81 or the manual paper feed tray 82 is transported to the registration rollers 13 with the transport rollers 12a arranged along the paper transport path S and is transported by the transfer roller 10 at a timing where the leading edge of the recording paper is aligned with the leading edge of the toner image on the intermediate transfer belt 61 and then the toner image is transferred to the recording paper Subsequently the record ing paper passes through the fixing unit 7 so that unfixed toner on the recording paper is melted by heat and adheres to the recording paper and then the recording paper is dis charged to the paper discharge tray 91 through the transport rollers 12b 0103 When there is a request for duplex printing on a recording paper in a state where the simplex printing as desc
19. erformed in the adjustment step using at least two types of data of detection images having different intervals as data of detection images including the plurality of detection patterns 0018 According to the present invention since the method includes the formation step and the adjustment step and the adjustment of color misalignment is performed using at least two types of data of detection images having different intervals a plurality of adjustment choices can be provided for the adjustment of color misalignment As a result the adjustment of color misalignment can be performed with a given level of precision depending on occasions such as those when performing initial settings or when performing mainte nance after use ofthe color image forming apparatus That is to say the detection can be performed with an optimal level of precision depending on the conditions Furthermore the amount oftoner consumed can be suppressed whichever type of data of detection images is used to perform adjustment of color misalignment In a specific embodiment of the present invention since a plurality of types of data of detection images are used the adjustment of color misalignment can be performed in a sequential or stepwise manner from rough Feb 14 2013 adjustment to fine adjustment In this case the correction of color misalignment can be precisely performed BRIEF DESCRIPTION OF THE DRAWINGS 0019 FIG 1 is a schematic cross sectional fron
20. fine adjustment of color misalignment ends thereby ending the adjustment of color misalignment 0134 Furthermore if there is no color misalignment in Step S13 NO in Step S13 the fine adjustment of color misalignment ends thereby ending the adjustment of color misalignment 0135 In this manner according to the image forming apparatus 100 according to this embodiment or the color misalignment adjusting method using the image forming apparatus 100 since the first data D1 and the second data D2 having different intervals are used to perform adjustment of US 2013 0039680 Al color misalignment two adjustment choices can be provided for the adjustment of color misalignment As a result the adjustment of color misalignment can be performed with a given level of precision depending on occasions such as those when performing initial settings or when performing mainte nance after use of the image forming apparatus 100 That is to say the detection can be performed with an optimal level of precision depending on the conditions Furthermore the amount of toner consumed can be suppressed whichever type of data of detection images is used to perform adjustment of color misalignment In this embodiment since the first data D1 and the second data D2 are used the adjustment of color misalignment can be sequentially performed from rough adjustment to fine adjustment In this case the correction of color misalignment can be precisely performed
21. fter the adjustment of positional misalign ment using the adjustment means will be described in more detail First the detection patterns P1 P2 P3 and P4 respec tively corresponding to the four respective colors which function as references are set It is assumed that the detection patterns P1 P2 P3 and P4 are arranged at constant intervals Furthermore four detection patterns P1 P2 P3 and P4 form one detection pattern block symbol PB shown in FIGS 3 and 4 and such a detection pattern block PB is repeatedly formed a plurality of times in the sub scanning direction of the sensor portions 310 imaging devices hereinafter referred to as a sub scanning direction thereby forming a plurality of detection pattern blocks PB The storage portion 303 stores data of detection images of four detection patterns P1 P2 P3 and P4 and a plurality of detection pattern blocks PB that have been formed in this manner and intervals between the detec tion patterns P1 P2 P3 and P4 hereinafter referred to as reference intervals as data of reference detection images 0109 At the time of detection in the adjustment of color misalignment four image stations sequentially form the detection patterns P1 P2 P3 and P4 see FIGS 3 and 4 respectively corresponding to the four respective colors in the sub scanning direction on the intermediate transfer belt 61 0110 The intervals between the detection patterns P1 P2 P3 and P
22. harges generated in a gap on the downstream side adja cent to the primary transfer portion in the movement direction M of the intermediate transfer belt 61 Such variations in the charge level in the same toner image decrease the transfer margin when transferring a toner image on the intermediate transfer belt 61 to a sheet 0098 Therefore the pre transfer charging unit 8 is used to uniformly charge a toner image before transfer to a sheet so that the variations in the charge level in the same toner image are cancelled which makes it possible to improve the transfer margin in the secondary transfer 0099 Furthermore the apparatus main body 110 is pro vided with a paper transport path S such that a recording paper from the paper feed tray 81 and the manual paper feed tray 82 is transported via the transfer roller 10 and the fixing unit 7 to the paper discharge tray 91 Arranged in the vicinity of the paper transport path S are pickup rollers 11a and 11b a plurality of transport rollers 12a to 124 registration rollers 13 the transfer roller 10 and a heat roller 71 and a pressure roller 72 in the fixing unit 7 0100 The registration rollers 13 temporarily hold a recording paper that is being transported on the paper trans port path S Then the registration rollers 13 transport the recording paper to the transfer roller 10 at a timing where the leading edge of the toner image on the photosensitive drums 3 is aligned with the leading e
23. ile suppressing the amount of toner consumed in correction of color mis alignment 0115 Next the color misalignment adjusting method using the above described adjustment means the first data D1 and the second data D2 will be described in detail with reference to FIG 5 0116 Ifthere is a request to perform initial settings of the image forming apparatus 100 for example when performing inspection in the plant when installing the image forming apparatus 100 or when performing correction of color mis alignment as designated by the user manual operation these occasions being conditions preset by the user YES in Step S1 the first data D1 the patterns for rough adjustment is read from the storage portion 303 Step S2 0117 After the first data D1 is read in Step S2 the image forming portion 102 uses the photosensitive body units 4 corresponding to the four respective colors to form the detec tion patterns P1 P2 P3 and P4 on the intermediate transfer belt 61 based on the first data D1 and its related data refer ence interval etc Step 83 which corresponds to the forma tion step in the present invention 0118 After the detection patterns P1 P2 P3 and P4 are formed on the intermediate transfer belt 61 as shown in FIG 3 in Step S3 actual intervals between adjacent detection patterns P1 P2 P3 and P4 are detected by the sensor portions 310 Step S4 0119 The data actually detected in Step S4 and the first
24. ing of a device that forms out puts an image on a recording paper at an image formation position based on document image data printing image data and the like and a constituent component such as an MPU that controls the device 0107 Incidentally the image forming apparatus 100 according to this embodiment is provided with an adjustment means for adjusting positional misalignment in order to cor rect color misalignment of an image The adjustment means includes sensor portions 310 that are provided in the image forming portion 102 see FIGS 3 and 4 The main control portion 300 controls the image forming portion 102 to per form adjustment of positional misalignment using the adjust ment means so that detection patterns respectively corre sponding to the four respective colors see P1 P2 P3 and P4 shown in FIGS 3 and 4 are formed on the intermediate transfer belt 61 the sensor portions 310 are used to detect whether or not there is positional misalignment between the detection patterns P1 P2 P3 and P4 and if there is posi tional misalignment the optical path length in the LSU is corrected As the sensor portions 310 in this example an imaging device such as a CCD is used The detection patterns formed on the intermediate transfer belt 61 are detected by Feb 14 2013 scanning and irradiating the imaging device and if color misalignment has occurred the optical path length in the LSU is corrected 0108 Hereina
25. ion images including the plurality of detection patterns
26. ize and the same shape In this color image forming apparatus the adjustment of color misalignment is performed using at least two types of data of detection images having different intervals as data of detection images including the plurality of detection patterns Perform ordinary operation S7 Continue image formation Perform fine adjustment YES Read patterns for fine adjustment S10 Form pattern images S11 Detect pattern images S12 S13 NO Detect color misalignment between colors Correct color misalignment END Patent Application Publication Feb 14 2013 Sheet 1 of 4 US 2013 0039680 A1 FIG 1 108 amo 100 li OJ Lezo pe es OF 90 7 72 71b 12c TO ACG 19 103 OO OO OTO TOC TN DA eae Pe 13 12d EZ E Patent Application Publication Feb 14 2013 Sheet 2 of 4 US 2013 0039680 A1 FIG 2 100 300 Main control portion Input portion Display portion 302 90 Storage portion Optical unit Image processing operation portion Facsimile portion Image forming Network I F portion Patent Application Publication Feb 14 2013 Sheet 3 of 4 US 2013 0039680 A1 FIG 3 Sub scanning D1 310 Patterns for rough adjustment Gc lo IN ae 61 TLE EEE PB E 35 3 Blocks ss 310 pitaj KC HLL FIG 4 Sub scanning D 510 Patterns for fine adjustment direction W mari a Main scanning direction 310
27. nsferred to a recording paper by a transfer roller 10 that forms a second transfer mechanism portion disposed in a contact position where the recording paper is in contact with the intermediate transfer belt 61 Note that as the configuration of the second transfer mechanism portion not only transfer rollers but also other transfer con figurations such as those employing corona chargers or trans fer belts can be used 0094 At this time the transfer roller 10 is supplied with a voltage high voltage having a polarity opposite the polar ity of the charged toner for transferring toner to the recording paper in a state where a transfer nip is formed between the transfer roller 10 and the intermediate transfer belt 61 The transfer nip is formed between the transfer roller 10 and the intermediate transfer belt 61 by the transfer roller 10 and the drive roller 62 pressing against each other In order to maintain the transfer nip steadily either one of the transfer roller 10 and the drive roller 62 is a hard roller made of a hard material e g metal and the other is an elastic roller made of a soft material e g elastic rubber or resin material such as foamed resin 0095 When transferring a toner image from the interme diate transfer belt 61 to a recording paper with the transfer roller 10 toner may remain on the intermediate transfer belt 61 without being transferred to the recording paper The toner that has remained on the
28. nt between installation positions when installing the image forming por tion 102 such as the plurality of photosensitive body units 4 has to be substantially eliminated Thus with the technique at the time of the present application it is difficult to perform adjustment of color misalignment using the second data D2 when the color misalignment amount may be significant for example at the time of initial settings 0138 In this embodiment although the adjustment of color misalignment is performed with respect to four colors the number of colors is not limited to this For example any number is possible as long as it is a plural 0139 Furthermore in this embodiment although the first data D1 and the second data D2 are used to perform adjust ment of color misalignment the number of data types of detection images is not limited to this For example three or more data types of detection images may be used In this case the adjustment of color misalignment can be performed in a stepwise manner from rough adjustment to fine adjustment and therefore the correction of color misalignment can be more precisely performed 0140 Note that the color image forming apparatus accord ing to the present invention showing this embodiment as an Feb 14 2013 example is applicable also to other image forming appara tuses such as copiers printers and facsimile machines 0141 The present invention may be embodied in various other forms
29. on the photosensitive body is developed with toner and the toner image is formed on a transfer member such as an intermediate transfer belt see JP 2003 149907A Patent Document 1 for example 0004 The image forming apparatus according to Patent Document 1 includes a plurality of image forming portions respectively corresponding to a plurality of colors wherein images of the respective colors are transferred in a superim posed manner from the plurality of image forming portions to an endless belt transfer member and then the images trans ferred in a superimposed manner are transferred in a batch to a recording paper forming a color image on the recording paper 0005 In the image forming apparatus as described in Patent Document 1 due to factors such as misalignment between installation positions of a plurality of image forming portions occurring when installing the plurality of image forming portions errors in the optical path length of a laser beam changes in the optical path warping of an LED func tioning as a light source caused by the environmental tem perature or the like misalignment between the positions of images of the respective colors formed on the photosensitive bodies may occur Due to this misalignment when transfer ring the respective colors from the plurality of photosensitive bodies in a superimposed manner the respective colors can not be transferred to desired positions on the endless belt and theref
30. onsumed the outline of the toner images becomes blurred and as a result the detection precision decreases In order to avoid a decrease in the detection precision it is necessary to increase the size of the detection patterns but this countermeasure is problem atic in that the amount of toner consumed cannot be sup pressed as described above 0010 Inorder to solve the above described problems it is an object of the present invention to provide a color image forming apparatus and a color misalignment adjusting method that can improve the detection precision while sup pressing the amount of toner consumed SUMMARY OF THE INVENTION 0011 In order to achieve the above described object the present invention is directed to a color image forming appa ratus wherein a plurality of detection patterns respectively corresponding to a plurality of colors are formed from a plurality of photosensitive body units respectively corre sponding to the plurality of colors onto a transfer member in a sub scanning direction of the transfer member intervals between detection patterns adjacent to each other in the sub scanning direction among the plurality of formed detection patterns are detected and adjustment of color misalignment is performed based on the detected intervals the plurality of detection patterns have the same size and the same shape and the adjustment of color misalignment is performed using at least two types of data of detection
31. ore color misalignment occurs on the endless belt 0006 In order to correct this color misalignment conven tional image forming apparatuses are provided with adjust ment means for adjusting positional misalignment 0007 According to this adjustment means detection pat terns respectively corresponding to a plurality of colors are formed on an endless belt in a sub scanning direction by a plurality of image forming portions specifically photosen sitive bodies Then the intervals between detection patterns adjacent to each other in the sub scanning direction among the detection patterns formed on the endless belt are detected using light from an optical sensor such as a CCD color misalignment at the time of development is detected using the detected data and the optical path length is automatically corrected according to the color misalignment amount 0008 In the conventional correction of color misalign ment as described in Patent Document 1 since toner images for detection are formed on the transfer member endless belt toner is consumed for the detection The amount of toner consumed increases in proportion to the detection pat Feb 14 2013 tern data as the size of the detection pattern data increases Thus in order to reduce the amount of toner consumed it is desirable to reduce the area of the detection patterns 0009 However if the area of the detection patterns is reduced in order to reduce the amount of toner c
32. polygon mirror to the photosensitive drums 3 Furthermore for the light exposure unit 1 other concepts can be used such as a concept employing a writing head in which light emitting elements such as EL electroluminescence elements or LEDs light emitting diodes are arranged in an array 0085 The light exposure unit 1 irradiates the photosensi tive drums 3 that are charged according to input image data thereby forming electrostatic latent images according to the image data on the respective surfaces of the photosensitive drums 3 0086 The toner cartridge units 21 are units containing toner and are configured such that the toner is supplied to development baths of the development units 2 In the appa ratus main body 110 of the image forming apparatus 100 the toner supplied from the toner cartridge units 21 to the devel opment baths of the development units 2 is controlled such that the toner concentration ofa developer in the development baths is constant 0087 The development units 2 make the electrostatic latent images formed on the respective photosensitive drums 3 visible with toner of the four colors Y M C and K Furthermore the photosensitive body units 4 further have a cleaning function of removing and recovering toner that has remained on the surfaces of the photosensitive drums 3 after development and image transfer 0088 The intermediate transfer belt unit 6 disposed above the photosensitive drums 3 includes
33. ribed above is completed and the trailing edge of the recording paper that has passed through the fixing unit 7 is positioned between the last transport rollers 126 and a branching portion Sa on the paper transport path S the trans port rollers 12b are rotated in reverse and therefore the recording paper is guided to the transport rollers 12c and 124 US 2013 0039680 Al Then the recording paper that has been transported to the transfer nip through the registration rollers 13 undergoes printing on its back face and then is discharged onto the paper discharge tray 91 0104 The thus configured image forming apparatus 100 according to this embodiment includes essential constituent components shown in FIG 2 Specifically the image forming apparatus 100 is provided with a main control portion 300 that controls various operations of the image forming apparatus 100 an input portion 301 on which a user directly performs an input operation a display portion 302 that displays informa tion such as an image a storage portion 303 that stores image data and the like an image processing operation portion 304 that performs an image processing operation a network inter face 306 network I F that is connected to the outside via a network 305 the optical unit 90 that scans a document the image forming portion 102 that forms an image ofa document on a recording paper and a facsimile portion 308 that is connected to the outside that transmits a
34. t reading device 108 is provided above the document placement platen 92 0082 Image data processed in the image forming appara tus 100 corresponds to a color image using a plurality of colors colors consisting of black K cyan C magenta M and yellow Y in this example Accordingly for each unit group of the development units 2 the photosensitive body units 4 including photosensitive bodies in the present inven tion and the toner cartridge units 21 a plurality of units four units respectively corresponding to black cyan magenta and yellow in this example are provided in order to form a plurality of types four types in this example of images corresponding to the respective colors and these units form image stations for the respective colors four colors in this example Feb 14 2013 0083 In the photosensitive body units 4 charging units 5 are charging means for uniformly charging the surfaces of photosensitive drums 3 to a predetermined potential and as the charging units 5 charging units of contact type such as rollers or brushes can be used as well as those of charger type as shown in FIG 1 0084 The light exposure unit 1 is configured as a laser scanning unit LSU including a laser emitting portion and reflective mirrors The light exposure unit 1 is provided with a polygon mirror scanned by a laser beam and optical ele ments such as lenses and mirrors for guiding the laser beam reflected by the
35. t view showing the overall configuration an image forming appara tus according to an embodiment 0020 FIG 2 is a schematic block diagram showing essen tial constituent components of the image forming apparatus according to this embodiment 0021 FIG 3 is a diagram showing detection patterns for rough adjustment used in the adjustment of color misalign ment according to this embodiment 0022 FIG 4 is a diagram showing detection patterns for fine adjustment used in the adjustment of color misalignment according to this embodiment 0023 FIG 5 is a flowchart for the adjustment of color misalignment according to this embodiment DESCRIPTION OF REFERENCE NUMERALS 0024 1 Light exposure unit 0025 2 Development unit 0026 3 Photosensitive drum 0027 4 Photosensitive body unit 0028 5 Charging unit 0029 6 Intermediate transfer belt unit 0030 7 Fixing unit 0031 8 Pre transfer charging unit 0032 10 Transfer roller 0033 11a 116 Pickup roller 0034 12a 12b 12c 12d Transport roller 0035 13 Registration roller 0036 21 Toner cartridge unit 0037 61 Intermediate transfer belt 0038 62 Drive roller 0039 63 Idler roller 0040 64 Intermediate transfer roller 0041 65 Cleaning unit 0042 71 Heat roller 0043 71a Heater 0044 715 Temperature detector 0045 72 Pressure roller 0046 73 External heating belt 0047 81 Paper feed tray 0048 82 Manual paper feed tray 0049 90 Optical unit
36. ta and that after the adjustment of color misalignment using the first data is performed the adjustment of color misalignment using the second data is performed 0014 According to the present invention since the rough adjustment of color misalignment is performed based on the first data having a large interval after which the fine adjust ment of color misalignment is performed based on the second US 2013 0039680 Al data having a small interval the correction of color misalign ment can be precisely performed 0015 Theabove described configuration may be such that the adjustment of color misalignment is performed based on a preset condition using the first data and the second data 0016 Inthis case the rough adjustment ofcolor misalign ment using the first data can be performed based on a preset condition e g at the time of initial settings where the color misalignment amount may be significant and the fine adjust ment of color misalignment using the second data can be periodically performed based on a preset condition in ordi nary use e g the time As a result since the rough adjust ment of color misalignment using the first data has been performed in advance misalignment in the fine adjustment of color misalignment using the second data is slight and the adjustment of color misalignment can be more precisely per formed On the other hand if the adjustment of color mis aligament using the second data is performed
37. without departing from the spirit gist or essen tial characteristics thereof The embodiments disclosed in this application are to be considered in all respects as illustrative and not limiting The scope of the invention is indicated by the appended claims rather than by the foregoing description All variations and modifications falling within the meaning and range of equivalency of the appended claims are intended to be embraced therein 0142 Furthermore the present invention is effective for color image forming apparatuses What is claimed is 1 A color image forming apparatus wherein a plurality of detection patterns respectively cor responding to a plurality of colors are formed from a plurality of photosensitive body units respectively cor responding to the plurality of colors onto a transfer member ina sub scanning direction of the transfer mem ber intervals between detection patterns adjacent to each other in the sub scanning direction among the plu rality of formed detection patterns are detected and adjustment of color misalignment is performed based on the detected intervals the plurality of detection patterns have the same size and the same shape and the adjustment of color misalignment is performed using at least two types of data of detection images having dif ferent intervals as data of detection images including the plurality of detection patterns 2 The color image forming apparatus according to claim 1
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