JP4565649B2 - Color image forming apparatus - Google Patents

Description

The present invention is a color image forming equipment for transferring superimposed on the transfer sheet to form a respective color color developed image on the photosensitive member, and more particularly, color adjustment between several different colors imaging of automatic control of color adjustment About.

Japanese Patent No. 2573855 Japanese Patent Laid-Open No. 11-65208 Japanese Patent Laid-Open No. 11-102098 JP-A-11-249380 JP 2000-112205 A.

  This type of color matching adjustment and test pattern detection used therefor are disclosed in, for example, Patent Document 1, and several types of test pattern detection methods are disclosed in Patent Document 2, Patent Document 3, Patent Document 4, and Patent Document 5. ing. These toners support the transfer paper and are transported along the arrangement of the photosensitive drums of each color, and the toners of the respective colors are located near the both ends of the width on the transfer belt for transferring the toner image on each photosensitive drum to the transfer paper. The marks are formed in a predetermined arrangement pattern, the toner marks at each end are read by each of the pair of optical sensors, and the positions of the marks in the mark arrangement (pattern) are calculated based on the read signals. The shift amount dy of each color image from the reference position in the sub-scanning direction y (transfer belt moving direction), the shift amount dx in the main scanning direction x (transfer belt width direction), and the effective line length of the main scanning line The shift amount dLx and the main scanning line skew dSq are calculated.

  According to the specification of Japanese Patent No. 2573855, the reflection mirror in the laser beam path for image exposure is actuated by using a stepping motor in correspondence with these deviation amounts, magnification, sub-scanning direction inclination, parallel movement, etc. It has been proposed to perform registration correction by adjusting, and to perform registration correction by controlling the driving of the photosensitive drum and the transfer belt.

  Incidentally, actual image formation cannot be performed between the detection of the deviation amount and the correction of registration, that is, the color matching adjustment. In addition, the developer may be consumed or the transfer belt may become dirty.

  The first object of the present invention is to automatically perform color matching adjustment in a situation where the necessity thereof is high, and to detect a shift between superimposed images of each color in color image formation relatively easily. The second object is to improve the reliability of detection.

(1) A plurality of image forming mechanisms (6a-6d / 7a-7d) that can be attached to and detached from the aircraft,
Transfer means (10, 11a to 11d) including a transfer belt (10);
Replacement detection means (41, 69a to 69d / 79a to 79d) for detecting replacement of the image forming mechanism;
When the replacement detection unit detects replacement of the image forming mechanism, a test pattern forming unit (1) for forming a test pattern including a plurality of marks by the image forming mechanism on the transfer belt;
An optical sensor (20r / 20f) that reads the plurality of marks;
Calculating the end edges position of each mark which the light sensor is read, correctness check means based on mark reading or position difference between the two edges are in the mark width corresponding value determines whether successful (41) ,
A color image forming apparatus comprising:

  In addition, in order to make an understanding easy, the code | symbol of the corresponding element or the corresponding matter of the Example which is shown in drawing and mentions later is added to the parenthesis for reference. The same applies to the following.

(2) In the color image forming apparatus according to (1), the correctness / incorrectness check means (41) determines in advance that the number of data samples within a predetermined output range among the photosensor outputs at the edge of the mark. A color image forming apparatus , wherein correctness / incorrectness is checked based on whether or not it is within a specified range (31 in FIG. 12) .

(3) The color image according to (1) or (2), wherein the correctness check means (41) calculates a mark position based on read data of a mark determined to be normal except for a mark determined to be incorrect. Forming equipment.

(4) In the color image forming apparatus according to (1) or (2), the test pattern forming means (1) forms a plurality of sets of test patterns, and the correctness check means (41) further includes each test. It calculates the respective center positions of the plurality of marks of the pattern, to verify the appropriateness of the distribution of the calculated center position color image forming apparatus according to claim (SPC in Fig. 9).

(5) In the color image forming apparatus of (4), wherein the distribution of pre-Symbol centric position to remove the mark reading data of a test pattern distribution is determined to be unsuitable prior SL-centered position is in proper performing the color matching adjustment to correct the colors shift on the basis of the mark reading data of the determined test pattern (SPC in Fig. 9, DAC of FIG. 8, DAD) color image forming apparatus according to claim.

  Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

  FIG. 1 shows an outline of the mechanism of an image forming apparatus that implements the present invention in one mode. This image forming apparatus is a digital color copier having a multi-function, in which an image scanner SCR, an automatic document feeder ADF, a sorter SOR, and others are assembled in a color printer PTR. In addition, when print data as image information is given from a host PC such as a personal computer (hereinafter referred to as PC) via a communication interface, the system configuration can print it out (image output).

  FIG. 2 shows the mechanism of the color printer PTR. The image data of each color generated by the scanner SCR is image data for color recording (hereinafter referred to as Bk (black), Y (yellow), C (cyan)) and M (magenta) in the image processing 40 (FIG. 3). , Recorded image data or simply image data) and then sent to a writing unit (exposure device) 5 of the printer PTR. The writing unit 5 is a laser that is modulated with image data for M, C, Y, and Bk recording on each of the photosensitive drums 6a, 6b, 6c, and 6d for M, C, Y, and Bk recording in accordance with the recorded image data. The light beam is scanned and projected to form an electrostatic latent image. Each electrostatic latent image is developed with each of the M, C, Y, and Bk toners by the developing units 7a, 7b, 7c, and 7d to form toner images (visual images) of the respective colors.

  On the other hand, the transfer paper is conveyed from the paper feed cassette 8 onto the transfer belt 10 of the transfer belt unit, and each color image (developed image) developed and formed on each photosensitive drum is transferred to the transfer units 11a, 11b, 11c and 11d. Are sequentially transferred onto the transfer paper, and after being superimposed, are fixed by the fixing device 12. After the fixing, the transfer paper is discharged out of the machine.

  The transfer belt 10 is a translucent endless belt supported by the driving roller 9, the tension roller 13a, and the driven roller 13b. The tension roller 13a pushes down the belt 10 with a spring (not shown), and therefore the tension of the belt 10 is substantially constant. It is.

  In order to prevent the above-described color shift (color shift) in the overlay transfer, the printer PTR uses the exposure device 5 to bring the photoconductor drums 6a, 6b, 6c and 6d to the front (front side in FIG. A test pattern for position detection (FIG. 5) is written and developed on the front and back (back side in FIG. 2; hereinafter referred to as rear), developed, transferred onto the transfer belt 10, and transferred to the transfer belt 10. Is detected by the reflection type optical sensors 20f (front side) and 20r (rear side), thereby detecting the writing position deviation, inclination, magnification, and the like of the exposure device 5 with respect to the photosensitive drums 6a, 6b, 6c, 6d. In addition, the writing timing of the exposure device 5 with respect to each photosensitive drum is corrected so as to eliminate the color misregistration due to these.

  FIG. 3 shows an electric system of the copying machine shown in FIG. In the document scanner SCR that optically reads a document, the reflected light of the lamp irradiation on the document is condensed on a light receiving element by a mirror and a lens in the reading unit 24. The light receiving element (CCD in this embodiment) is in a sensor board unit SBU (hereinafter simply referred to as SBU), and an image signal converted into an electric signal in the CCD is a digital signal, that is, a read image. After being converted to data, the data is output from the SBU to the image processing 40.

  The system controller 26 and the process controller 1 communicate with each other via the parallel bus Pb and the serial bus Sb. The image processing 40 performs data format conversion for the data interface between the parallel bus Pb and the serial bus Sb.

  The read image data from the SBU is transferred to the image processing 40, and the image processing corrects the signal deterioration due to the quantization to the optical system and the digital signal (signal deterioration of the scanner system: distortion of the read image data due to the scanner characteristics). Then, the image data is transferred to the copy function controller MFC and written into the memory MEM. Alternatively, processing for printer output is performed and given to the printer PTR.

  That is, in the image processing 40, the read image data is stored in the memory MEM and reused, and the laser printer PTR is output to the video data control VDC (hereinafter simply referred to as VDC) without storing it in the memory MEM. There are some jobs that output images. As an example of storing in the memory MEM, when copying a plurality of originals, the reading unit 4 is operated only once, the read image data is stored in the memory MEM, and the stored data is read out a plurality of times. As an example in which the memory MEM is not used, when only one original is copied, the read image data may be processed as it is for printer output, so there is no need to write to the memory MEM.

  First, when the memory MEM is not used, the image processing 40 performs image reading correction on the read image data and then performs image quality processing for conversion into area gradation. The image data after the image quality processing is transferred to the VDC. With respect to the signal changed to the area gradation, post-processing relating to dot arrangement and pulse control for reproducing the dots are performed by the VDC, and a reproduction image is formed on the transfer paper in the exposure unit 5 of the laser printer PTR.

  When data is stored in the memory MEM and additional processing is performed at the time of reading, for example, image direction rotation, image composition, etc., the image data subjected to image reading correction is accessed through the parallel bus Pb. It is sent to the control IMAC (hereinafter simply referred to as IMAC). Here, based on the control of the system controller 26, the access control of the image data and the memory module MEM (hereinafter simply referred to as MEM), the development of the print data of the external personal computer PC (hereinafter simply referred to as PC) (character code / Character bit conversion) and compression / decompression of image data for effective use of memory. The data sent to the IMAC is stored in the MEM after data compression, and the stored data is read out as necessary. The read data is expanded, returned to the original image data, and returned from the IMAC to the image processing 40 via the parallel bus Pb.

  After returning to the image processing 40, image quality processing and pulse control at VDC are performed, and a visible image (toner image) is formed on the transfer paper in the exposure unit 5.

  The FAX transmission function, which is one of the composite functions, performs image reading correction on the read image data of the document scanner SCR by the image processing 40, and passes to the FAX control unit FCU (hereinafter simply referred to as FCU) via the parallel bus Pb. Forward. The FCU performs data conversion to a public line communication network PN (hereinafter simply referred to as PN), and transmits the data to the PN as FAX data. In FAX reception, line data from the PN is converted into image data by the FCU, and transferred to the image processing 40 via the parallel bus Pb and CDIC. In this case, special image quality processing is not performed, dot rearrangement and pulse control are performed in the VDC, and a visible image is formed on the transfer paper in the exposure unit 5.

  In a situation where a plurality of jobs, for example, a copy function, a FAX transmission / reception function, and a printer output function operate in parallel, the system controller 26 and the process allocate the reading unit 24, the exposure unit 5, and the right to use the parallel bus Pb to the job. Control is performed by the controller 1.

  The process controller 1 controls the flow of image data, and the system controller 6 controls the entire system and manages the activation of each resource. The function selection of this digital multi-function copier is selected and input through the operation board OPB, and processing contents such as a copy function and a FAX function are set.

  The printer engine 4 shown in FIG. 3 includes an electric device and an electric sensor such as a motor, a solenoid, a charger, a heater, a lamp, and an electric circuit (driver) that are incorporated in the printing mechanism, that is, the image forming mechanism shown in FIG. ) And a detection circuit (signal processing circuit), the operation of these electric circuits is controlled by the process controller 1, and the detection signal (operation state) of the electrical sensor is read by the process controller 1.

  Refer to FIG. 2 again. Four latent image carrying units 60a to 60d (6a are shown in FIG. 4), each of which includes a charging roller, a photosensitive drum, a cleaning mechanism, and a static elimination lamp, each centering on the photosensitive drums 6a, 6b, 6c, and 6d. 60a; the other symbols 60b to 60d are not shown), and the four developing units 7a to 7d each have a unit configuration that can be attached to and detached from the machine body.

  FIG. 4 (a) shows the unit front surface of the latent image carrying unit 60a including the photosensitive drum 6a and the developing unit 7a for developing the latent image on the photosensitive drum 6a. The front end 61 of the shaft of the photosensitive drum 6a of the latent image carrier unit 60a protrudes through the front cover 67 ((b) of FIG. 4) of the unit 60a. The end 61 is pointed in a conical shape so that it can easily enter a positioning hole for the photosensitive drum 6a (not shown) opened in the face plate 81 (FIG. 4B) of the face plate unit 80 for axial alignment. ing.

  The face plate 81 has positioning holes for receiving the shafts (61) of the photosensitive drums 6a to 6d and the developing roller shafts (71) of the developing units 7a to 7d, respectively, by fixing the face plate 81 to the base frame. The positions of the front end portions of the shafts of the photosensitive drums 6a to 6d and the developing roller shafts of the developing units 7a to 7d are determined precisely. The face plate 81 has large-diameter holes into which normally closed micro switches 69a to 69d and 79a to 79d (FIG. 6) for detecting the presence / absence of each latent image carrier unit and for detecting the presence / absence of each development unit are fitted. The microswitch is supported by a printed circuit board 82. The inner surface of the face plate 81 is covered with an inner cover 84, and the outer surface on the printed circuit board 82 side is covered with an outer surface cover 83.

  The developing unit 7a has a threaded pin 64 protruding from the front of the unit for operating the micro switch 69a, and a similar threaded pin 74 is also present in the developing unit 7a. The same applies to other latent image carrying units and developing units.

  4 (b) and 4 (c) show longitudinal sections of the latent image carrying unit 60a of the 64 pins with screws. (B) shows a state in which the latent image carrier unit 60a mounted on the copying machine is new and the charging roller 62 has not been driven to rotate yet. (C) shows that the charging roller 62 has already been driven to rotate. Indicates that there is a state.

  The charging roller 64 for uniformly charging the photosensitive drum 6a contacts the photosensitive drum 6a and rotates at substantially the same peripheral speed as the photosensitive drum 6a. Dirt on the surface of the charging roller 64 is wiped off with the cleaning pad 63. The rotating shaft 62a of the charging roller 64 is rotatably supported by a front side support plate 68 of the latent image carrying unit 60a via a bearing. The connecting sleeve 65 is fixed to the tip of the rotating shaft 62a and rotates integrally with the rotating shaft 62a. At the center of the connecting sleeve 65, there is a hole having a square cross section, into which a substantially square prismatic leg 64b of a threaded pin 64 is fitted. The region having a length of about 2/3 on the male screw 64s side of the leg 64b is a square prism that engages with the square hole of the connecting sleeve 65, but the remaining length of about 1/3 on the tip side of the leg 64b. This area is in the shape of a round bar that can idle with respect to the connecting sleeve 65.

  As shown in FIG. 4 (b), there is a large-diameter male screw 64s between the leading pin 64p and the leg 64b of the threaded pin 64. In the new (unused) latent image carrying unit 60a, The return spring 66 is compressed by being screwed into the female screw hole of the cover 67. In this state, the protruding length of the pin 64 from the front surface of the unit is short. However, when the charging roller 62 is rotationally driven in this state, the threaded pin 64 is rotated thereby, and is moved in a direction approaching the face plate 81 due to screw connection with the female screw hole, so that the switching operation of the microswitch is performed. Hit the child. Just before the male screw 64s of the threaded pin 64 penetrates the female screw hole by this movement, the normally closed micro switch is switched from closed to open.

  As shown in FIG. 4C, when the male screw 64 s penetrates the female screw hole, the pin 64 is protruded by the return spring 66. As a result, the prismatic portion of the leg 64b of the pin 64 comes out of the square hole of the sleeve 65, and the pin 64 does not rotate even if the charging roller 62 rotates.

  Therefore, when a latent image carrier unit (for example, 60a) that has already been used is mounted on the copying machine as it is, the microswitch (69a) is always open (off). Even if a new (unused) latent image carrier unit (60a) is mounted, that is, the unit is replaced, the micro switch (69a) is closed until the charging roller (62) is driven to rotate ( ON). When the copier power is turned on, the micro switch (69a) is closed (on), and when the drive of the image forming mechanism is started and switched to open (off), it is understood that the power was turned on for the first time after unit replacement. . That is, it can be seen that the unit has been replaced immediately before the power is turned on. Similarly, detection of attachment of other latent image carrying units and developing units and detection of replacement with new ones are also performed. In the developing units 7 a to 7 d, a threaded pin 74 similar to the threaded pin 64 is provided on the leveling roller 73 that rotates in the same direction in synchronization with the developing roller 72, and the front cover 67 portion of the transfer roller 62. It is connected via a support mechanism similar to the support mechanism.

  When “color matching” is performed, a test pattern is formed on the transfer belt 10 of the printer PTR as shown in FIG. In other words, eight mark sets are sequentially formed at a set pitch (constant pitch) 7d + A + c after a vacant space of 4 pitches 4d of the mark pitch d starting from the start mark Msr of black Bk.

The first mark set is a next orthogonal mark group parallel to the main scanning direction x (the width direction of the transfer belt 10),
Black Bk first orthogonal mark Akr,
Yellow Y second orthogonal mark Ayr,
A cyan C third orthogonal mark Acr, and
The fourth orthogonal mark Amr of magenta M,
And the following oblique mark group forming an angle of 45 ° with respect to the main scanning direction x,
Bk first oblique mark Bkr,
Y second oblique mark Byr,
C third oblique mark Bcr, and
M fourth oblique mark Bmr,
Is included. The contents of the second to eighth mark sets are the same as the first mark set. The same test pattern as the above-described rear test pattern is also formed on the front at the same time. Of the symbols attached to the marks included in these test patterns, the suffix r indicates the rear side, and f indicates the front side.

  FIG. 6 shows the above-described microswitches 69a to 69d, 79a to 79d and optical sensors 20r and 20f for unit mounting detection, and an electric circuit for reading these detection signals. At the mark detection stage, a microcomputer (hereinafter referred to as MPU) 41 (hereinafter referred to as MPU) mainly composed of ROM, RAM, CPU, and FIFO memory for storing detection data, etc. is connected to D / A converters 37r, 37f, optical sensors 20r, Energization data designating energization current values of the 20f light emitting diodes (LEDs) 31r and 31f is given, and the D / A converters 37r and 37f convert the analog data into analog voltages, which are given to the LED drivers 32r and 32f. These drivers 32r and 32f energize the LEDs 31r and 31f with a current proportional to the analog voltage.

  The light generated by the LEDs 31r and 31f hits the transfer belt 10 through a slit (not shown), and most of the light is transmitted therethrough and slidably contacted with the back surface of the transfer belt 10 to suppress vertical vibration of the belt 10. The light is reflected by the plate 21, passes through the transfer belt 10, and further strikes the phototransistors 33r and 33f through a slit (not shown). As a result, the impedance between the collector and emitter of the transistors 33r and 33f becomes low, and the emitter potential rises. When the above-mentioned mark Msr or the like arrives at a position facing the LEDs 31r and 31f, the mark blocks light, so that the collector / emitter between the transistors 33r and 33f becomes high impedance, and the emitter voltage, that is, the photosensors 20r and 20f. The level of the detection signal decreases. Therefore, as described above, when the test pattern is formed on the moving transfer belt 10, the detection signals of the optical sensors 20r and 20f fluctuate between high and low. A high voltage means no mark, and a low voltage means a mark.

  The detection signals of the optical sensors 20r and 20f pass through the low-pass filters 34r and 34f for high-frequency noise removal, and are further calibrated to 0 to 5 V by the level calibration amplifiers 35r and 35f, and the A / D converter 36r, 36f.

  FIG. 13 shows the calibrated detection signal Sdr. Referring again to FIG. 6, the detection signals Sdr and Sdf are supplied to the A / D converters 36r and 36f, and further supplied to the window comparators 39r and 39f through the amplifiers 38r and 38f.

  The A / D converters 36r and 36f are provided with a sample hold circuit on the input side thereof and a data latch (output latch) on the output side, and when the MPU 41 gives the A / D conversion instruction signals Scr and Scf, The voltages of the detection signals Sdr and Sdf are held, converted into digital data, and held in the data latch. Therefore, when it is necessary to read the detection signals Sdr and Sdf, the MPU 41 can read the digital data representing the levels of the detection signals Sdr and Sdf, that is, the detection data Ddr and Sdf by giving the instruction signals Scr and Scf.

  The window comparators 39r and 39f generate level determination signals Swr and Swf at a low level L when the detection signals Sdr and Sdf are within a range of 2V or more and 3V or less, and when they are outside the range. The MPU 41 can immediately recognize whether or not the detection signals Sdr and Sdf are within the range by referring to these level determination signals Swr and Swf.

  FIG. 7 shows an outline of printer engine control, that is, print control of the MPU 41. When the operating voltage is applied to itself, the MPU 41 sets the signal level of the input / output port to the standby state, and also sets the internal registers and timers to the standby state (step m1). In the following, step No. is enclosed in parentheses. Alternatively, when indicating a step symbol, the word “step” is omitted, and the “No. Write only numbers or symbols.

  When the initialization (m1) is completed, the MPU 41 reads the state of each part of the mechanism and the electric circuit to check whether there is an abnormality that hinders image formation (m2, m3), and the micro switches 69a to 69d, 79a to If any of 79d is closed (on), the copier power is turned on immediately after the unit (latent image forming unit or developing unit) is not installed at the position of the closed microswitch or after being replaced with a new unit. It is.

  In order to check which is the case, the MPU 41 temporarily drives the image forming system (m21, m22). As a result, the transfer belt 10 is driven in the transfer paper conveyance direction, and the photosensitive drums 6a to 6d and the charging rollers 62,... Contacting with the photosensitive drums 6a to 6d and the developing rollers 72,. However, if it is immediately after replacement with a new unit, the micro switch that has been closed is switched to open (with attachment). If the unit is not installed, it remains closed.

  When the micro switch that has been closed is switched to open as a result of driving the image forming system, the MPU 41 closes from the open (PSd = H) to the micro switch that detects attachment / detachment of the Bk latent image forming unit, for example. When PSd = L), the print accumulation number register (one area on the non-volatile memory) addressed to the Bk latent image forming unit is cleared (Bk print accumulation number is initialized to 0), and the unit is replaced with the register FPC. Write “1” indicating that there is a hit (m24).

  When the micro switch is not switched to the open position, it is assumed that the unit is not installed, and an abnormality notification indicating that is given (m23-m4). If there is any other abnormality, it is displayed on the operation display board OPB (m21-m4). The state reading (m2) is repeated until there is no abnormality.

  If there is no abnormality, the energization of the fixing device is started, and it is checked whether the fixing temperature is the fixing possible temperature. If the fixing temperature is not, the standby display is displayed. (M5).

  Also, it is checked whether the fixing temperature is 60 ° C. or higher (m6). If the fixing temperature is lower than 60 ° C., the power of the copier is turned on after a long pause (not used) (for example, the first power source in the morning) On: Temporarily assume that the in-flight environment during suspension is large), display the color matching execution on the operation display board OPB (m7), and store it in the register (one area of memory) RCn of the MPU 41 in the nonvolatile memory at that time. Is written (m8), the machine temperature at that time is written in the register RTr of the MPU 41 (m9), “adjustment” (m25) is executed, and when that is finished, the register FPC is cleared. (M26). The content of “adjustment” (m25) will be described later with reference to FIG.

  When the fixing temperature is 60 ° C. or higher, it can be considered that the elapsed time from the previous power-off of the copier is short. In this case, it can be inferred that the change in the in-flight environment from just before the previous power-off to the present is small. However, it is checked whether the latent image forming unit 60a,... Or the developing units 7a to 7d of any color has been replaced, that is, whether information representing unit replacement has been generated in step m24 described above. (M10). If the information is present, that is, if the unit has been replaced, the above steps m7 to m9 are executed, and “adjustment” (m25) described later is executed.

  When the image forming unit (latent image forming unit or developing unit) has not been replaced, the MPU 41 waits for an operator input via the operation display board OPB and a command from the personal computer PC (m11). Here, when a “color matching” instruction is given from the operator via the operation display board OPB (m12), the MPU 41 executes the above-described steps m7 to m9 and executes “adjustment” (m25) described later. .

  When the fixing temperature is fixable temperature and each part is ready, if there is a copy start instruction from the operation display board OPB, or if there is a print start instruction corresponding to the print command from the personal computer PC from the system controller 26 The MPU 41 forms a specified number of images (m13, m14). In this image formation, every time one sheet is formed and ejected, the MPU 41, when it is color recording, print total number register, color print integration number register PCn, and Bk allocated to the nonvolatile memory. , Y, C, and the M print accumulated number register are incremented by one. When monochrome recording is performed, the data in the total print number register, monochrome print integration number register, and Bk print integration number register are incremented by one.

  The data in the Bk, Y, C, and M print integration number registers are initialized (cleared) to data representing 0 when the Bk, Y, C, and M latent image forming units are replaced with new ones, respectively.

  The MPU 41 checks whether there is an abnormality such as a paper trouble every time an image is formed, and reads the development density, fixing temperature, in-machine temperature, and other statuses after completing the designated number of printouts ( m15). If there is an abnormality, it is displayed on the operation display board OPB (m17), and the state reading (m15) is repeated until there is no abnormality.

  When the image formation can be resumed, that is, when normal, the MPU 41 checks whether the internal temperature at that time has changed by more than 5 ° C from the internal temperature at the previous color matching (data RTr in the register RTr). (M18). When there is a temperature change exceeding 5 ° C., the MPU 41 executes the above steps m7 to m9, and executes “color matching” (CPA) described later. When there is no temperature change exceeding 5 ° C, the value PCn of the color print accumulation number register PCn is 200 or more more than the value RCn (data of the register RCn) of the color print accumulation number register PCn at the previous color matching. When the number is 200 or more, the above steps m7 to m9 are executed, and “color matching” (CPA) described later is executed. If it is less than 200 sheets, it is checked whether or not the fixing temperature is the fixing possible temperature, and if it is not the fixing possible temperature, a standby display is displayed, and if it is the fixing possible temperature, a printable display is displayed (m20). Then, the process proceeds to “input reading” (m11).

  According to the control flow shown in FIG. 7, the MPU 41 (1) when the power is turned on when the fixing temperature is less than 60 ° C., (2) any of the Bk, Y, C and M imaging units is new. (3) When there is a color matching instruction from the operation display board OPB, (4) Complete the specified number of printouts, and the in-machine temperature is 5 ° from the in-machine temperature at the previous color matching. When the change exceeds C, and (5) the designated number of printouts are completed, and the color print cumulative number PCn is 200 or more than the value RCn at the previous color matching. Then, “adjustment” (m25) described below is executed.

  FIG. 8A shows the contents of “adjustment” (m25). In this “adjustment” (m25), first, in “process control” (m27), all image forming conditions such as charging, exposure, development and transfer are set to reference values, and the rear r or front f on the transfer belt 10 is set. In addition, Bk, Y, C, and M images are formed, the image density is detected by the optical sensor 20r or 20f, and the charging roller applied voltage, exposure intensity, and developing bias are adjusted so that they become reference values. Set. Then, “color matching” (CPA) is executed.

  FIG. 8B shows the contents of “color matching” (CPA). When proceeding to this “color matching” (CPA), the MPU 41 first transfers the image under the image forming conditions (parameters) set in the “process control” (m27) in “test pattern formation and measurement” (PFM). As shown in FIG. 5, start marks Msr, Msf and 8 sets of test patterns are formed on the belt 10 on the rear r and front f, and the marks are detected by the optical sensors 20r, 20f. The detection signals Sdr and Sdf are converted into digital data, that is, mark detection data Ddr and Ddf by the A / D converters 36r and 36f and read. Then, the position (distribution) of the center point of each mark on the transfer belt 10 is calculated. Further, an average pattern of the rear side 8 sets (an average value group of mark positions) and a similar average pattern of the front side 8 sets are calculated. The contents of this “test pattern formation and measurement” (PFM) will be described later with reference to FIG.

  When the average pattern is calculated, an image shift amount by each of the Bk, Y, C, and M image forming units is calculated based on the average pattern (DAC), and an adjustment for eliminating the shift based on the calculated shift amount. (DAD).

  FIG. 9 shows the contents of “test pattern formation and measurement” (PFM). As shown in FIG. 5, the MPU 41 proceeds to the surface of the rear side r and the front side f of the transfer belt 10 that is driven at a constant speed of, for example, 125 mm / sec. Formation of start marks Msr, Msf and 8 sets of test patterns with w of 1 mm, length A in the x direction of, for example, 20 mm, pitch d of, for example, 6 mm, and interval c between the sets of, for example, 9 mm is started. , Msf starts a timer Tw1 whose time limit value is Tw1 for the timing immediately before the light sensors 20r and 20f arrive immediately below (1), and waits for the timing. That is, it waits for the timer Tw1 to time out (2). When the timer Tw1 times out, this time, the timer Tw2 with a time limit value of Tw2 is started to time the last of the eight test patterns on the rear and front ends through the optical sensors 20r and 20f. (3).

  As already described, when the Bk, Y, C, or M mark is not present in the field of view of the optical sensors 20r and 20f, the detection signals Sdr and Sdf of the optical sensors 20r and 20f are at the high level H (5V) and the mark is present. The detection signal Sdr is at a low level L (0 V), and the detection signal Sdr varies as shown in FIG. A part of the fluctuation is enlarged and shown in FIG. In this case, the descending area where the level of the mark detection signal is reduced corresponds to the leading edge area of the mark, and the ascending area where the mark is rising corresponds to the trailing edge area of the mark. Between these is the area of the mark width w.

  In Step 4 of FIG. 9, the start comparator Msr, Msf arrives at the field of view of the optical sensors 20r, 20f and the detection signals Sdr, Sdf change from H to L, and the window comparator 39r or 39f of FIG. It waits for the detection signal Swr = L or Swf = L indicating that the signal Sdr or Sdf is at 2 to 3V. That is, it is monitored whether at least one edge region of the start marks Msr and Msf has arrived in the visual field of the optical sensors 20r and 20f.

  When the timer arrives, the timer Tsp whose time limit value is Tsp (for example, 50 μsec) is started. When the timer Tsp expires, the “timer Tsp interrupt” (TIP) shown in FIG. 10 is executed, and the timer interrupt is permitted (5). Then, the sampling number value Nos of the sampling number register Nos is initialized to 0, and writing to the r memory (rear side mark reading data storage area) and the f memory (front side mark reading data storage area) allocated to the FIFO memory in the MPU 41 is performed. The addresses Noar and Noaf are initialized to the start address (6). Then, it waits for the timer Tw2 to time out. That is, it waits for all of the eight sets of test patterns to finish passing through the visual fields of the optical sensors 20r and 20f (7).

  Here, with reference to FIG. 10, the content of the “interrupt of timer Tsp” (TIP) will be described. It should be noted that this process is executed every time the timer Tsp whose time limit value is Tsp expires. At the beginning of this processing, the MPU 41 restarts the timer Tsp (11) and instructs the A / D converters 36r and 36f to perform A / D conversion (12). That is, the instruction signals Scr and Scf are temporarily set to the A / D conversion instruction level L. Then, the sampling number value Nos in the sampling number register Nos, which is the number of instructions, is incremented by one (13).

  Thereby, the Nos × Tsp has elapsed since the detection of the leading edge of the start mark Msr or Msf (= light in the belt moving direction y along the surface of the transfer belt 10 based on the start mark Msr or Msf. This represents the current detection position on the transfer belt 10 by the sensors 20r and 20f.

  Then, it is checked whether the detection signal Swr of the window comparator 39r is L (the optical sensor 20r is detecting the edge portion of the mark and 2V ≦ Sdr ≦ 3V) (14). At the address Noar, the sampling number value Nos of the sampling number register Nos and the A / D conversion data Ddr (value of the mark detection signal Sdr of the optical sensor 20r) are written as write data (15). Then, the write address Noar of the r memory is incremented by 1 (16). When the detection signal Swr of the window comparators 39r and 39f is H (Sdr <2V or 3V <Sdr), data is not written to the r memory. This is for reducing the amount of data written to the memory and simplifying subsequent data processing.

  Next, similarly, it is checked whether the detection signal Swf of the window comparator 39f is L (the optical sensor 20f is detecting the edge of the mark and 2V ≦ Sdf ≦ 3V) (17). The sampling number value Nos of the sampling number register Nos and the A / D conversion data Ddf (value of the mark detection signal Sdf of the optical sensor 20f) are written as write data in the address Noaf of the f memory (15). Then, the write address Noaf of the f memory is incremented by 1 (19).

  Since such interrupt processing is repeatedly executed in the Tsp cycle, when the mark detection signals Sdr and Sdf of the optical sensors 20r and 20f change to high and low as shown in FIG. 14A, the FIFO in the MPU 41 In the r memory and the f memory allocated to the memory, only the digital data Ddr and Ddf of the detection signals Sdr and Sdf within the range of 2V to 3V shown in FIG. Stored. Since the sampling number value Nos of the sampling number register Nos is incremented by 1 in the Tsp cycle, and the transfer belt 10 moves at a constant speed, the number value Nos is determined on the transfer belt 10 based on the detected start mark. It shows the y position along the surface.

  Note that, as shown in FIG. 14B, the center position a of the descending area where the level of the mark detection signal is reduced and the center position of the ascending area which is rising next is within the range of 2V to 3V. The middle point Akrp of b is the center position of one mark Akr in the y direction, and similarly, the center position c of the descending region where the level of the mark detection signal that appears next to the mark is lowered, and the next rise The middle point Ayrp of the center position d of the rising area is the center position in the y direction of another mark Ayr. These mark center positions Akrp, Ayrp,... Are calculated by calculation CPA (FIGS. 11 and 12) of mark center point positions described later.

  Reference is again made to FIG. After the last mark of the last eighth set in the test pattern passes through the optical sensors 20r and 20f, the timer Tw2 times out. Then, the MPU 41 prohibits interruption of the timer Tsp (7, 8). As a result, the A / D conversion of the detection signals Sdr and Sdf in the Tsp cycle shown in FIG. 10 is stopped. The MPU 41 calculates the center position of the mark (CPA) based on the detection data Ddr and Ddf in the r memory and f memory of the FIFO memory therein, and each of the eight sets of patterns of the rear r and the front f. The appropriateness of the distribution of the detected mark center point position is verified, the inappropriate detection pattern (set) is deleted (SPC), and the average pattern of the appropriate detection pattern is obtained (MPA).

  FIG. 11 and FIG. 12 show the contents of “calculation of mark center point position” (CPA). Here, “calculation of mark center point position of rear r” (CPAr) and “calculation of mark center point position of front f” (CPAf) are executed.

  In the “calculation of mark center point position of rear r” (CPAr), the MPU 41 first initializes the read address RNoar of the r memory allocated to the FIFO memory inside thereof, and the data of the center point number register Noc is transferred to the first edge. It is initialized to 1 which means (21). Then, the data Ct of the one-edge region sample number register Ct is initialized to 1, and the data Cd and Cu of the descending number register Cd and the ascending number register Cu are initialized to 0 (22). Then, the read address RNoar is written in the edge area data group start address register Sad (23). The above is preparation processing for data processing of the first edge region.

  Next, the MPU 41 receives data (y position Nos: N · RNoar, detection level Ddr: D · RNoar) from the r memory address RNoar, and data (y position Nos: N · (RNoar + 1) from the next address RNoar + 1. ), Detection level Ddr: D · (RNoar + 1)), and first, whether the y position difference between the two data is E (for example, E = w / 2 = for example, a value corresponding to 1/2 mm) or less (on the same edge region). Check (24). If so, check whether the mark detection data Ddr is in a downward trend or an upward trend (25). If the mark detection data Ddr is in a downward trend, the data Cd in the downward count register Cd is incremented by 1 (27). If the tendency is upward, the data Cu of the upward number register Cu is incremented by 1 (26). Then, the data Ct in the one-edge sample number register Ct is incremented by one (28). Then, it is checked whether the r memory read address RNoar is the end address of the r memory (29). If the r memory read address RNoar is not the end address, the memory read address RNoar is incremented by 1 (30), and the above processing (24-30) is performed. ) Is repeated.

  When the y position (Nos) of the read data is changed to that of the next edge region, the position difference between the position data of the front and rear memory addresses checked in step 24 is larger than E, and the MPU 41 starts from step 24 in FIG. Proceed to step 31. Here, all the sampling data of one mark edge (leading edge or trailing edge) area have been checked for downward and upward tendency. Therefore, it is checked whether the sample number data Ct in the one-edge sample number register Ct at this time is an equivalent value in one edge region (in the range of 2V to 3V). That is, it is checked whether F ≦ Ct ≦ G (31). F is a lower limit (setting of the number of times of writing the sample value Ddr to the r memory while the detection signal Sdr is 2 V or more and 3 V or less when the leading edge or the trailing edge of the mark formed normally is detected. Value) and G are upper limit values (set values).

  If Ct is F ≦ Ct ≦ G, the correctness / incorrectness of the data of one mark edge that has been normally read and stored is completed, and the result is “appropriate”. It is checked whether the obtained detection data group has a downward trend or an upward trend as a whole of the edge region (2V or more and 3V or less) (32, 34). In this embodiment, if the data Cd of the descending number register Cd is 70% or more of the sum Cd + Cu of the data Cu of the descending number register Cu and the data Cu of the ascending number register Cu, the memory edge No. If the address Down is written to the address addressed to Noc (33), and the data Cu in the ascending number register Cu is 70% or more of Cd + Cu, the memory edge No. Information Up indicating an increase is written in the address addressed to Noc (35). Further, the average value of the y position data of the edge region, that is, the center point position (a, b, c, d,... Write to the address addressed to Noc (36).

  Next, the edge No. It is checked whether Nos has become 130 or more, that is, calculation of the center positions of the leading edge region and trailing edge region of all of the start mark Msr and the eight sets of mark patterns has been completed. If this has been completed, or if all of the stored data has been read from the r memory, the mark center point position is calculated based on the edge center point position data (y position calculated in step 36). (39). That is, the memory edge No. The address data (falling / rising data & edge center point position data) is read, and the position difference between the center point position of the preceding falling edge area and the center point position of the immediately following rising edge area is the width of the mark in the y direction. It is checked whether it is within the range corresponding to w. If it is out of range, these data are deleted. If it is within the range, the average value of these data is set as the center point position of one mark. Write to memory. If mark formation, mark detection, and detection data processing are all appropriate, with respect to rear r, start mark Msr and 8 sets of marks (1 set 8 marks × 8 sets = 64 marks), a total of 65 mark center points Position data is obtained and stored in memory.

  Next, the MPU 41 executes “calculation of the mark center point position of the front f” CPAf, and performs the data processing of the above-mentioned “calculation of the mark center point position of the rear r” CPAr similarly to the measurement data in the f memory. carry out. With respect to the front f, if mark formation, measurement, and measurement data processing are all appropriate, start mark Msf and 8 sets of marks (64 marks), a total of 65 mark center point position data are obtained and stored in memory. Is done.

  Refer to FIG. 9 again. When the mark center point position is calculated as described above (CPA), the MPU 41 shows the mark center point position data group written in the memory in the next “verification of pattern of each set” (SPC) as shown in FIG. The central point distribution corresponding to the mark distribution is verified. Here, data deviating from the mark distribution equivalent to that shown in FIG. 5 is deleted in units of sets, and only the data set corresponding to the mark distribution shown in FIG. leave. If all are appropriate, 8 sets of data remain on the rear r side and 8 sets of data remain on the front f side.

  Next, the MPU 41 changes the center point position data of the first mark in each set after the second set to the first center point position of the first set (first set) of the data set on the rear r side. The center point position data of the second to eighth marks are also changed by the changed difference value. That is, the center point position data group of each set after the second set is changed to a value shifted in the y direction so that the top of each set is aligned with the top of the first set. Similarly, the center point position data in each set after the second set on the front f side is also changed.

Next, the MPU 41 calculates average values Mar to Mhr (FIG. 15) of the center point position data of each mark in all sets on the rear r side by “calculation of average pattern” (MPA), and also on the front f side. Average values Maf to Mhf (FIG. 15) of the center point position data of each mark of all sets are calculated. These average values are virtual average position marks distributed as shown in FIG.
MAkr (representative of Bk rear orthogonal mark),
MAyr (representative of Y rear orthogonal mark),
MAcr (representative of C rear orthogonal mark),
MAmr (representative of M rear orthogonal mark),
MBkr (representative of Bk rear diagonal mark),
MByr (representative of the Y rear oblique mark),
MBcr (representative of C rear oblique mark), and
MBmr (representative of M rear diagonal mark), and
MAkf (representative of Bk front orthogonal mark),
MAyf (representative of Y front orthogonal mark),
MAcf (representative of C front orthogonal mark),
MAmf (representative of M front orthogonal mark),
MBkf (representative of Bk front oblique mark),
MByf (representative of Y front oblique mark),
MBcf (representative of the front diagonal mark of C), and
MBmr (representative of M front diagonal mark)
The center point position of is shown.

  The above is the content of “test pattern formation and measurement” (PFM) shown in FIG.

  Reference is again made to FIG. See also FIG. In the displacement amount calculation (DAC) shown in FIG. 8B, the MPU 41 calculates the image formation displacement amount as follows. The calculation (Acy) of the image forming deviation amount of Y is specifically shown below.

Sub-scanning deviation amount dyy:
Deviation amount of the difference (Mbr−Mar) in the center point position between the Bk orthogonal mark MAkr and the Y orthogonal mark MAyr on the rear r side with respect to the reference value d (FIG. 5)
dyy = (Mbr−Mar) −d.

Main scanning deviation amount dxy:
Deviation amount with respect to the reference value 4d (FIG. 5) of the difference (Mfr−Mbr) in the center point position between the rear r-side orthogonal mark MAyr and the oblique mark MByr
dxyr = (Mfr−Mbr) −4d
And the deviation of the difference (Mff−Mbf) between the center point positions of the orthogonal mark MAyf on the front f side and the oblique mark MByf with respect to the reference value 4d (FIG. 5)
dxyf = (Mff−Mbf) −4d
And average value
dxy = (dxyr + dxyf) / 2
= (Mfr-Mbr + Mff-Mbf-8d) / 2.

Skew dSqy:
Difference in center point position between the orthogonal mark MAyr on the rear r side and the orthogonal mark MAyf on the front f side
dSqy = (Mbf−Mbr).

Main scanning line length deviation amount dLxy:
A value obtained by subtracting the skew dSqy = (Mff−Mfr) from the difference (Mff−Mfr) of the center point position between the rear r side oblique mark MByr and the front f side oblique mark MByf.
dLxy = (Mff−Mfr) −dSqy
= (Mff-Mfr)-(Mbf-Mbr).

  The other C and M image forming deviation amounts are calculated in the same manner as the calculation related to Y (Acc, Acm). Although Bk is substantially the same, in this embodiment, since color matching in the sub-scanning direction y is based on Bk, the positional deviation amount dyk in the sub-scanning direction is not calculated for Bk (Ack). .

  In the deviation adjustment (DAD) shown in FIG. 8B, the MPU 41 adjusts the image formation deviation amount of each color as follows. The Y shift amount adjustment (Ady) is specifically shown below.

Adjustment of sub-scanning deviation amount dy:
The start timing of image exposure (latent image formation) for forming the Y toner image is set by shifting the calculated shift amount dyy from the reference timing (y direction).

Adjustment of main scanning deviation amount dxy:
The transmission timing (x direction) of the image data at the head of the line to the exposure laser modulator of the writing unit 5 with respect to the line synchronization signal representing the head of the line in image exposure (latent image formation) for Y toner image formation, It is set by shifting the calculated deviation amount dxy from the reference timing.

Adjustment of skew dSqy:
The rear r side of the mirror extending in the x direction is supported by a fulcrum and the front f side of the writing unit 5 is projected to the photosensitive drum 6b by reflecting the laser beam modulated by the Y image data facing the photosensitive drum 6b. , And is supported by a block slidable in the y direction. The skew dSqy can be adjusted by moving this block back and forth in the y direction by a y drive mechanism mainly composed of a pulse motor and a screw. In “adjustment of skew dSqy”, the pulse motor of this y driving mechanism is driven to drive the block from the reference y position by an amount corresponding to the calculated skew dSqy.

Adjustment of main scanning line length deviation amount dLxy:
The frequency of the pixel synchronization clock for allocating image data in units of pixels on the line is set to reference frequency × Ls / (Ls + dLxy). Ls is the reference line length.

  The other adjustments of C and M image formation deviation amounts are adjusted in the same manner as the adjustment for Y (Adc, Adm). Although Bk is generally the same, in this embodiment, since color matching in the sub-scanning direction y is based on Bk, the positional deviation amount dyk in the sub-scanning direction is not adjusted for Bk (Adk). . Until the next “color matching”, a color image is formed under the adjusted conditions.

1 is a perspective view showing an external appearance of a color copying machine that implements the present invention in one mode. FIG. It is a block diagram which shows the outline | summary of the internal mechanism of print PTR shown in FIG. It is a block diagram which shows the outline | summary of the system configuration | structure of the electric system of the color copying machine shown in FIG. (A) is a front view showing the front surface of the latent image forming unit 60a and the developing unit 7a shown in FIG. 2, (b) and (c) are longitudinal cross-sectional views of the threaded pin 64 part shown in (a), ( (b) shows a state immediately after the unit 60a is new and mounted on the copying machine, and (c) shows a state after the charging roller 62 is rotationally driven after mounting. FIG. 3 is a plan view of the transfer belt 10 shown in FIG. 2, schematically showing each color mark formed on the surface thereof. It is a block diagram which shows the structure of a part of the process controller 1 shown in FIG. It is a flowchart which shows the outline | summary of the print control of the microcomputer (MPU) 41 shown in FIG. (A) is a flowchart showing an outline of “adjustment” m25 shown in FIG. 7, and (b) is a flowchart showing an outline of “color matching” CPA shown in (a). FIG. 9 is a flowchart showing the contents of a “test pattern formation and measurement” PFM shown in FIG. FIG. 10 is a flowchart showing the contents of interrupt processing permitted in step 5 shown in FIG. 9. FIG. 10 is a flowchart showing a part of the content of “calculation of mark center point position” CPA shown in FIG. 9. 10 is a flowchart showing the remainder of the “calculation of mark center point position” CPA shown in FIG. 9. FIG. 3 is a plan view showing a distribution of color marks formed on a transfer belt 10 shown in FIG. 2 and a time chart showing a level change of a detection signal Sdr obtained by reading a color mark of an optical sensor 20r. (A) is a time chart showing an enlarged part of the time chart of the detection signal Sdr shown in FIG. 13, and (b) is the A / D conversion data of the detection signal shown in (a) shown in FIG. 6 is a time chart showing only the range written in the FIFO memory inside the MPU 41 shown in FIG. The average value data Mar,... Calculated by the “average pattern calculation” MPA shown in FIG. 9 and the virtual marks MAkr,. It is a top view which shows a row | line | column.

Explanation of symbols

PTR: color printer SCR: scanner ADF: automatic document feeder SOR: sorter PC: personal computer 5: writing unit 6a to 6d: photosensitive drums 7a to 7d: developing unit 8: paper feed cassette 9: drive roller 10: transfer belt 11a to 11d: transfer device 12: fixing device 13a: tension roller 13b: driven roller 20r, 20f: optical sensor 24: reading unit SBU: sensor board unit Pb: parallel bus Sb: serial bus 41: MPU (microcomputer)
60a: latent image forming unit 61: end of shaft body 62: charging roller 62a: rotating shaft 63: cleaning pad 64: screwed pin 65: sleeve 66: return spring 67: front cover 68: support plates 69a to 69d: micro Switch 71: End of shaft 72: Developing roller 73: Leveling roller 74: Screwed pins 79a to 79d: Micro switch 80: Face plate unit 81: Face plate 82: Printed circuit board 83: Outer cover 84: Inner cover

Claims (5)

Multiple image forming mechanisms that can be attached to and detached from the aircraft,
A transfer means including a transfer belt;
Replacement detection means for detecting replacement of the image forming mechanism;
Test pattern forming means for forming a test pattern composed of a plurality of marks by the image forming mechanism on the transfer belt when the replacement detecting means detects replacement of the image forming mechanism;
An optical sensor for reading the plurality of marks;
And correctness check means for calculating the end edges position of each mark which the light sensor is read, based on the mark reading or position difference between the two edges are in the mark width corresponding values to determine whether successful,
A color image forming apparatus comprising:   The color image forming apparatus according to claim 1, wherein the correctness / incorrectness check unit is configured to determine whether a number of data samples within a predetermined output range is within a predetermined range among the optical sensor outputs at the edge of the mark. A color image forming apparatus that performs a correctness check based on the above.   3. The color image forming apparatus according to claim 1, wherein the correctness check unit calculates a mark position based on read data of a mark determined to be normal except for a mark determined to be a read error. Calculated in the color image forming apparatus according to claim 1 or 2, wherein the test pattern forming unit forms a test pattern of a plurality of sets, the correctness checking means further each center position of the plurality of marks of each test pattern And verifying the suitability of the calculated distribution of the center position. In the color image forming apparatus according to claim 4, distribution before Symbol centric position to remove the mark reading data of a test pattern distribution is determined to be unsuitable prior SL-centered position is determined to be suitable test A color image forming apparatus that performs color matching adjustment for correcting a color shift based on pattern mark reading data .

Images