JP2007163525A - Adjustment method of printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure high adjustment accuracy so as to sufficiently deal with a printer for business use and to avoid such a failure that stability and durability are degraded by operating each function element in optimum condition. <P>SOLUTION: The strobe time ts of printheads 3bk, 3c, 3m and 3y is controlled to successively attach a plurality of adjustment patch images V1, V2... different from each other in toner density Ct to a transfer section 5. A reflection-type density sensor 6 having a light emitting section 6s and light receiving sections 6bk and 6co for detecting the toner density Ct detects the toner densities (detected densities) Ct... of the respective adjustment patch images V1, V2... in a transfer section 5 and the strobe time ts is reset so as to obtain the detected density Ct closest to a preliminarily set reference density Co. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is suitable for use in adjusting a printing apparatus that controls a print head of an exposure unit to attach toner corresponding to print data to a photosensitive member and transfers the toner to printing paper via a transfer unit. The present invention relates to a method for adjusting a simple printing apparatus.

  In general, an image forming apparatus (printing apparatus) using an electrophotographic system controls a print head of an exposure unit to attach toner corresponding to print data to a photosensitive drum (photosensitive body) and adheres to the photosensitive drum. The toner is primarily transferred to the transfer unit, and further has a function of secondarily transferring (printing) the toner of the transfer unit onto the conveyed printing paper.

By the way, in this type of printing apparatus, as disclosed in, for example, Japanese Patent Laid-Open No. 2000-305327, print density adjustment is performed periodically or as necessary in order to ensure print quality. The printing apparatus disclosed in the publication is a printing apparatus that includes a printing unit that prints print data on a recording medium, and an adjustment unit that adjusts the print density so as to maintain print quality in the printing unit. Setting means for arbitrarily setting the execution time of the print density adjustment by the means. Further, the print density adjustment is performed by drawing a predetermined pattern on the photosensitive drum, attaching the toner, measuring the toner adhesion amount with a density sensor, and obtaining a print correction value from a comparison with an expected value. .
JP 2000-305327 A

  However, the above-described conventional printing apparatus (print density adjustment) has the following problems.

  First, in the case of a printing device that is used for business purposes, especially high quality and stability are required for print quality, but the conventional print density adjustment is, so to speak, only one-point adjustment. Therefore, there is a limit to realizing high density adjustment, and it cannot cope with high adjustment accuracy required for business use.

  Second, since one adjustment element is adjusted for the toner density, there is a possibility that appropriate adjustment is not performed. For example, if the output of the density sensor is offset due to any factor, adjustments such as compensating for it with the output of the print head are performed, so it is limited to superficial adjustments and each functional element is operated in an optimal state. Not only cannot be performed, but stability and durability may be impaired.

  An object of the present invention is to provide a method for adjusting a printing apparatus that solves the problems in the background art.

  In order to solve the above-described problems, the printing apparatus adjustment method according to the present invention controls the print heads 3bk, 3c, 3m, and 3y of the exposure unit 2 to correspond to the print data on the photoconductors 4bk, 4c, 4m, and 4y. When adjusting the printing apparatus 1 that attaches the toner to the printing paper P via the transfer unit 5 and adjusts the strobe time ts of the print heads 3bk, 3c, 3m, and 3y, the toner density Ct is controlled. A plurality of adjustment patch images V1, V2,. 5 is detected and toner density (detected density) Ct... Of each adjustment patch image V1, V2. So as to be characterized in that so as to reset the strobe time ts.

  In this case, according to a preferred aspect of the invention, it is possible to detect toner densities Ct at a plurality of positions in the adjustment patch images V1, V2,. It should be noted that the predetermined adjustment patch image V11 located in the middle of the plurality of adjustment patch images V1, V2,... Is desirably set by the reference strobe time to.

  On the other hand, another method for adjusting a printing apparatus according to the present invention controls the print heads 3bk, 3c, 3m, and 3y of the exposure unit 2 to solve the above-described problems, so that the photoconductors 4bk, 4c, 4m, and 4y are used. When adjusting the printing apparatus 1 that attaches toner corresponding to the print data and transfers the toner to the printing paper P via the transfer unit 5, the light emitting unit 6s and the light receiving units 6bk, 6co that detect the toner density Ct are provided. Calibration reference surfaces 7bk, 7co that are selectively displaced to detection positions Xbk, Xco that are detected by the density sensor 6 or to non-detection positions Xr that are not detected by the density sensor 6 are provided for the reflective density sensor 6 that is provided. At the time of adjustment, the calibration reference planes 7bk and 7co are displaced to the detection positions Xbk and Xco, and the current value Is of the light emitting unit 6s is sequentially changed, whereby the light receiving units 6bk, Detecting an output value Dr of the co, characterized in that so as to reset the current value Is of the light emitting portion 6s so that the closest output value Dr to the reference value Do previously set.

  In this case, according to a preferred aspect of the invention, it is possible to detect the concentration at a plurality of positions on the calibration reference planes 7bk and 7co and obtain the averaged output value Dr. In addition, a plurality of calibration reference surfaces 7bk and 7co are provided corresponding to the plurality of light receiving portions 6bk and 6co provided in the density sensor 6, and the calibration reference surfaces 7bk and 7co are arranged in gray colors having different densities. Can do. Further, the calibration reference surfaces 7bk and 7co can be formed on the calibration plate 7 that is rotated by the rotation drive unit 8 and displaced to the detection positions Xbk and Xco or the non-detection position Xr.

  According to the adjustment method of the printing apparatus 1 according to the present invention by such a method, the following remarkable effects are obtained.

  (1) In detecting the toner density Ct, since fine and precise detection is performed over a predetermined range, it is possible to achieve high-precision density adjustment, and in particular, high quality and stability in print quality in applications. Therefore, it is possible to sufficiently cope with the business-use printing apparatus 1 for which high-precision adjustment is required.

  (2) Calibration of the density sensor 6 and / or adjustment of the print heads 3bk, 3c, 3m, 3y can be performed individually to operate each functional element in an optimum state, and stability and durability can be improved. It is possible to avoid damaging defects.

  (3) By detecting toner densities Ct... At a plurality of positions in the adjustment patch images V1, V2,... And obtaining an average detected density Ct, a more accurate density adjustment can be effectively realized.

  (4) By detecting the density at a plurality of positions on the calibration reference planes 7bk and 7co and obtaining the averaged output value Dr according to a preferred embodiment, more accurate density adjustment can be effectively realized.

  (5) According to a preferred embodiment, a plurality of calibration reference surfaces 7bk and 7co are provided corresponding to a plurality of light receiving portions 6bk and 6co provided in the density sensor 6, and the calibration reference surfaces 7bk and 7co have different densities. If the gray color is used, optimum calibration (adjustment) for each of the light receiving portions 6bk and 6co can be realized, and more accurate density adjustment can be realized easily and effectively.

  (6) If the calibration reference planes 7bk, 7co are formed on the calibration plate 7 that is rotated by the rotation drive unit 8 and displaced to the detection position Xbk, Xco or the non-detection position Xr according to a preferred embodiment, 7bk, 7co can be set easily and reliably, and it can contribute to space saving by downsizing.

  Next, the best embodiment according to the present invention will be given and described in detail with reference to the drawings.

  First, the structure of the exposure part and transfer part which implement the adjustment method of the printing apparatus 1 which concerns on this embodiment is demonstrated with reference to FIGS.

  FIG. 3 shows an extracted color printing unit U3 provided in the printing apparatus 1. The color printing unit U3 includes an exposure unit 2 and a transfer unit 5 as main components. The transfer unit 5 includes an endless intermediate transfer belt 11, and this intermediate transfer belt 11 is bridged between a driving roller 12 disposed on the upper side, guide rollers 13 and 14 disposed on the lower side, and a secondary transfer roller 21. Configure. Reference numeral 22 denotes a pressure contact roller that presses the printing paper P to be printed (transferred) to the intermediate transfer belt 11 located on the peripheral surface of the secondary transfer roller 21.

  The exposure unit 2 is attached to the intermediate transfer belt 11 located between the driving roller 12 and the guide roller 14. The color printing unit U3 includes a yellow printing unit 67y, a magenta printing unit 67m, a cyan printing unit 67c, and a black printing unit 67bk arranged at predetermined intervals from the rear side in the transport direction of the intermediate transfer belt 11, and the exposure unit 2 includes: Photosensitive drums (semiconductor drums) 4y, 4m, 4c, and 4bk that are in contact with the intermediate transfer belt 11 are provided by being incorporated in the printing units 67y, 67m, 67c, and 67bk, respectively. Reference numerals 15y, 15m, 15c and 15bk denote primary transfer rollers for bringing the intermediate transfer belt 11 into contact with the peripheral surfaces of the photosensitive drums 4y, 4m, 4c and 4bk, respectively.

  Each printing unit 67bk, 67c, 67m, 67y includes print heads 3bk, 3c, 3m, 3y using LEDs, and each print head 3bk, 3c, 3m, 3y is connected to the print controller 72. Thus, a control signal corresponding to the print data (image data) is given from the print controller 72 to each print head 3bk, 3c, 3m, 3y, and the strobe time ts of each print head 3bk, 3c, 3m, 3y is set. Be controlled. The toner having a density corresponding to the strobe time ts adheres to the photosensitive drums 4bk, 4c, 4m, and 4y, and the toner on the photosensitive drums 4bk, 4c, 4m, and 4y is primarily transferred onto the intermediate transfer belt 11. The

  On the other hand, a reflection type density sensor 6 supported by the support plate 31 is disposed in the vicinity of the drive roller 12. As shown in FIG. 4, the density sensor 6 includes a light emitting unit 6 s using an infrared LED and light receiving units 6 bk and 6 co using a photodiode, and is connected to the print controller 72, so that it is placed on the intermediate transfer belt 11. The density (toner density) Ct of the primary transferred toner is detected. In this case, the light receiving unit 6bk detects a black density, and the light receiving unit 6co detects a color density other than black. For this reason, the sensitivity of the light receiving unit 6bk is set higher than the sensitivity of the light receiving unit 6co.

  Further, the rotation drive unit 8 using the stepping motor 8s is attached to the support plate 31, and the semicircular calibration plate 7 shown in FIG. 5A is attached to the rotation shaft of the stepping motor 8s. The calibration plate 7 bisects the surface facing the density sensor 6, and forms a calibration reference surface 7 bk with a dark gray color that performs calibration on the light receiving unit 6 bk side on one side and receives light on the other side. A calibration reference plane 7co with a light gray color for calibration on the part 6co side is formed. The stepping motor 8s is connected to the print controller 72. As a result, when the stepping motor 8s is driven and controlled, and the calibration plate 7 is rotated by a predetermined angle as shown in FIG. 5B, the calibration reference surface 7bk or 7co can be detected by the density sensor 6 (detection). The detected position Xbk or Xco can be displaced. 5A shows a non-detection position Xr where the density sensor 6 cannot detect the calibration plate 7 (non-detection state), and this non-detection position Xr is the home position of the calibration plate 7. FIG.

  In this way, a plurality of calibration reference surfaces 7bk and 7co are provided corresponding to the plurality of light receiving portions 6bk and 6co provided in the density sensor 6, and the calibration reference surfaces 7bk and 7co are arranged in gray colors having different densities. By doing so, it is possible to realize optimum calibration (adjustment) for each of the light receiving portions 6bk and 6co, and to easily and effectively realize density adjustment with high accuracy. Further, if the calibration reference planes 7bk and 7co are formed on the calibration plate 7 that is rotated by the rotation drive unit 8 and displaced to the detection positions Xbk and Xco or the non-detection position Xr, the calibration reference planes 7bk and 7co are set. There is an advantage that it can be easily and reliably performed and contributes to space saving by downsizing.

  Next, an adjustment method of the printing apparatus 1 according to the present embodiment will be described according to the flowcharts shown in FIGS. 1 and 2 with reference to FIGS.

  First, a calibration method (adjustment method) of the density sensor 6 will be described with reference to the flowchart shown in FIG. Since the calibration plate 7 is used for calibration of the density sensor 6, reference values Do... Corresponding to the calibration reference surfaces 7bk and 7co are set in advance. In this case, in the initial state (at the time of factory shipment), the rated current is passed through the light emitting unit 6s, and the output voltages (output values) of the light receiving units 6bk and 6co when the concentrations of the calibration reference surfaces 7bk and 7co are detected are obtained. It can be set as a reference value Do.

  Further, the calibration of the density sensor 6 can be performed periodically according to the period of use or the number of times of use, and can be executed by selecting a calibration mode if necessary. The calibration process of the density sensor 6 is automatically performed according to a preset sequence program.

  Assume that the set use period has elapsed and the calibration process of the density sensor 6 is executed. First, the print controller 72 drives and controls the stepping motor 8s to rotate the calibration plate 7 to the use position Xco. In this case, the calibration plate 7 rotates from the home position shown in FIG. 5A and is set to the use position Xco shown by the solid line in FIG. 5B (step S1). As a result, the density sensor 6 is in a detection state with respect to the light gray calibration reference plane 7co. Since the setting needs to be accurately positioned, if the density sensor 6 detects the edge of the calibration plate 7, the calibration plate 7 is rotated by a set angle and then stopped. Accordingly, if the density sensor 6 does not detect the edge of the calibration plate 7 even after a predetermined time has elapsed after outputting the rotation command to the stepping motor 8s, the print controller 72 performs error processing such as error display. .

  Next, the current value Is of the light emitting unit 6s is sequentially changed, that is, the current value Is is sequentially changed by N steps (for example, 1 to 128 steps), whereby the output value (output voltage) Dr of the light receiving unit 6co in each step. Are detected and temporarily stored in the memory 73 (steps S2 and S3). When the detection process in the final step is completed, the calibration plate 7 is rotated by one step (for example, 0.36 °), and the above-described detection processes in steps S2 and S3 are performed similarly (steps S4 and S5). Further, the calibration plate 7 is sequentially rotated up to M steps (for example, 10 steps) set in advance, and the same detection process is repeated for each step. When the above detection process is completed, an average value of the output values Dr... (10 times) is obtained for each current value Is... (Steps S4 and S6). Thus, if the density at a plurality of positions on the calibration reference surface 7co is detected and the averaged output value Dr is obtained, highly accurate density adjustment can be effectively realized.

  If the output value (average value) Dr is obtained, the output value Dr closest to the preset reference value Do is selected, and the current value Is corresponding to the output value Dr is reset as the current value flowing through the light emitting unit 6s. (Setting change) is performed (step S7). Therefore, when the density sensor 6 detects the density of the color toner, a current based on the reset current value Is flows to the light emitting unit 6s.

  When the above process is completed, the print controller 72 controls the stepping motor 8s to rotate the calibration plate 7 to the use position Xbk. In this case, the calibration plate 7 is rotated by a set angle from the use position Xco and is set to the use position Xbk indicated by the phantom line in FIG. 5B (steps S8 and S1). As a result, the density sensor 6 is in a detection state with respect to the dark gray calibration reference plane 7bk. At this time, the print controller 72 monitors the output value Dr of the density sensor 6 and performs error processing such as error display when there is no change exceeding a certain value.

  If the output value Dr is normal, the detection process and the calculation process in steps S2 to S7 are executed as in the case of the calibration reference plane 7co described above. As a result, the calibrated current value Is is also reset (setting change) for the light receiving unit 6bk. Therefore, when the density sensor 6 detects the density of the black toner, a current based on the reset current value Is flows to the light emitting unit 6s.

  Next, a method for adjusting the exposure unit 2 will be described with reference to a flowchart shown in FIG. First, the print controller 72 drives and controls the stepping motor 8s and rotates the calibration plate 7 at the detection position Xbk to return to the home position shown in FIG. 5A (step S11). The adjustment of the exposure unit 2 is the adjustment of the strobe time ts for the print heads 3y, 3m, 3c, and 3bk provided in the printing units 67y, 67m, 67c, and 67bk. The adjustment process is sequentially performed for each of the print heads 3y, 3m, 3c, and 3bk. The adjustment process is automatically performed according to a preset sequence program.

  First, the print head 3y is selected, and adjustment processing for the print head 3y is performed (step S12). In this case, the print controller 72 controls the strobe time ts of the print head 3y to form a plurality of adjustment patch images having different toner densities Ct on the photosensitive drum 4y. As shown in FIG. 6, the intermediate transfer belt 11 The adjustment patch images V1, V2,..., V11, V12,... V21 are sequentially attached on top (step S13). The number of adjustment patch images V1 to be illustrated is 21. In this case, the adjustment patch image V11 located in the middle (middle) is set by the reference strobe time to. Therefore, in the initial state (at the time of shipment from the factory), the toner density corresponding to the reference strobe time to is set as the reference density Co.

  Each of the adjustment patch images V1... V21 is set so that the first adjustment patch image V1 becomes the darkest and becomes gradually lighter in stages, and the last adjustment patch image V1 becomes the thinnest. At this time, a strobe time ts... Of each adjustment patch image V1... V21 is set by sequentially adding or subtracting a predetermined time with respect to the reference strobe time to. Each of the adjustment patch images V1... Is a so-called solid coating in which the entire surface is uniform.

  On the other hand, the adjustment patch images V1 attached to the intermediate transfer belt 11 are conveyed by the intermediate transfer belt 11, so that the density sensor 6 detects when the first adjustment patch image V1 reaches the position of the density sensor 6. (Step S14). Accordingly, the density sensor 6 detects the toner density (detected density) Ct in the adjustment patch image V1, and primarily stores it in the memory 73 (step S15). In this case, as shown in FIG. 6, the detection position (detection range) is an intermediate range Zm (about ½ of the whole) of the adjustment patch image V1 (see V2), and is before the intermediate range Zm. Detection is not performed for the range Zf (about ¼ of the entire range) and the rear range Zr (about ¼ of the entire range) on the rear side of the intermediate range Zm. This ensures stable detection.

  The detection process is executed X times (for example, 32 times) at predetermined intervals (step S16). When the X detection processes are completed, an average value of the detected densities Ct... Is obtained by calculation (step S17). As described above, if toner densities at a plurality of positions in the adjustment patch images V1, V2,... Are detected and the averaged detected density Ct is obtained, highly accurate density adjustment can be effectively realized.

  The above detection process is similarly executed up to the last adjustment patch image V21 (steps S18, S14...). Then, from the obtained detected density (average value) Ct, the detected density Ct closest to the preset reference density Co is selected, and the strobe time ts corresponding to the detected density Ct is set as the strobe time ts of the print head 3y. Setting (setting change) is performed (step S19). The above adjustment principle is shown in FIG. FIG. 7 shows the relationship of the detected density Ct with respect to the strobe time ts, and tss is the strobe time to be reset. Thereby, the adjustment process for the print head 3y is completed. Thereafter, the same adjustment process is sequentially performed on the remaining print heads 3m, 3c, 3bk (steps S20, S12,...). Each of the adjustment patch images V1,... Is then secondarily transferred (printed) to the printing paper P by the secondary transfer roller 21, and the printed printing paper P is discharged to the outside via the paper discharge unit. .

  Therefore, according to the adjustment method of the printing apparatus 1 according to the present embodiment, since the fine and precise detection is performed over a predetermined range when the toner density Ct is detected, the density adjustment with high accuracy is realized. In particular, it can sufficiently cope with a commercial printing apparatus 1 that requires high quality and stability in printing quality in use, and can ensure high adjustment accuracy. Further, by individually executing calibration of the density sensor 6 and / or adjustment of the print heads 3bk, 3c, 3m, and 3y, each functional element can be operated in an optimum state, and stability and durability are impaired. The trouble can be avoided.

  Although the best embodiment has been described in detail above, the present invention is not limited to such an embodiment, and the detailed configuration, shape, quantity, numerical value, and the like do not depart from the spirit of the present invention. It can be changed, added, or deleted arbitrarily.

  For example, although the case where the calibration plate 7 rotating as the calibration reference surfaces 7bk and 7co is used is illustrated, the calibration sheet can be replaced by another configuration such as moving the calibration sheet back and forth in the linear direction. Moreover, although the case where the two reference planes 7bk and 7co for calibration corresponding to the light receiving portions 6bk and 6co are provided is illustrated, it does not exclude one case. Although the adjustment method according to the present invention is suitable for application to the business printing apparatus 1, it can be applied to a printing apparatus or a device incorporating a printing mechanism for various other purposes.

The flowchart which shows the adjustment method which concerns on the best embodiment of this invention, Comprising: The process sequence of the calibration method of a density sensor, The flowchart which shows the processing procedure of the adjustment method which is the adjustment method, and the adjustment method of an exposure part (print head), Configuration diagram of the main part of a printing apparatus that implements the adjustment method, Principle configuration diagram of the concentration sensor calibrated by the adjustment method, Figure of the calibration plate (calibration reference plane) attached to the concentration sensor Pattern diagram of an adjustment patch image used in the adjustment method, Relationship diagram between strobe time and detected density showing the adjustment principle by the adjustment method,

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printing apparatus 2 Exposure part 3bk Print head 3c ... Print head 4bk Photoreceptor 4c ... Photoreceptor 5 Transfer part 6 Density sensor 6s Light emission part 6bk Light reception part 6co Light reception part 7 Calibration board 7bk Reference plane for calibration 7co Reference plane for calibration P Printing Paper ts Strobe time to Reference strobe time V1 ... Adjustment patch image Ct Detection density (toner density)
Co reference concentration Xbk detection position Xco detection position Xr non-detection position

Claims (7)

  When controlling the print head of the exposure unit to attach toner corresponding to the print data to the photoconductor, and adjusting the printing apparatus that transfers the toner to the printing paper through the transfer unit, the strobe time of the print head is set. A plurality of adjustment patch images having different toner densities are sequentially attached to the transfer unit, and each of the adjustment portions in the transfer unit is adjusted by a reflective density sensor having a light emitting unit and a light receiving unit for detecting the toner density. A method for adjusting a printing apparatus, comprising: detecting a toner density (detected density) of a patch image; and resetting the strobe time so that a detected density closest to a preset reference density is obtained.   The method of adjusting a printing apparatus according to claim 1, wherein the toner density at a plurality of positions in the adjustment patch image is detected and the averaged detected density is obtained.   3. The adjustment method for a printing apparatus according to claim 1, wherein a predetermined adjustment patch image located in the middle of the plurality of adjustment patch images is set based on a reference strobe time.   A light emitting unit that controls the print head of the exposure unit to attach toner corresponding to the print data to the photosensitive member, and detects the toner density when adjusting a printing apparatus that transfers the toner to the printing paper via the transfer unit And a reflection-type density sensor having a light receiving portion, a calibration reference plane that is selectively displaced to a detection position that is detected by the density sensor or a non-detection position that is not detected by the density sensor is provided. By displacing the calibration reference plane to the detection position and sequentially changing the current value of the light emitting unit, the output value of the light receiving unit is detected so that the output value is closest to the preset reference value. A method for adjusting a printing apparatus, comprising resetting a current value of the light emitting unit.   5. The method of adjusting a printing apparatus according to claim 4, wherein the output values obtained by detecting densities at a plurality of positions on the reference plane for calibration are obtained.   6. The calibration reference plane is provided in a plurality corresponding to a plurality of light receiving sections provided in the density sensor, and each calibration reference plane is colored by a gray color having a different density. Method for adjusting the printing apparatus.   7. The method of adjusting a printing apparatus according to claim 4, wherein the calibration reference surface is formed on a calibration plate that is rotated by a rotation drive unit and displaced to the detection position or the non-detection position.