JP2005164922A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the waiting and starting time for an image data print in which not much gradation property of the image is required by carrying out simple gradation control in which the number of patches for gradation control in waiting time is reduced and furthermore, carrying out formal gradation in idle time for a job, etc. <P>SOLUTION: In an image forming apparatus, by having control simplifying automatic gradation compensation instructed and at the same time, having simplified automatic gradation control carried out only when judged that simplification is necessary and carrying out the conventional automatic gradation control anew by utilizing the idle time of the image forming apparatus, starting of the image forming apparatus is thus speeded up and the gradation property of the image forming apparatus is not spoiled. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  In the image forming apparatus that requires automatic image adjustment represented by image density level adjustment at the time of starting up the main body, the present invention waits until the image can be formed after starting up the main body by shortening the adjustment time. The present invention relates to an image forming apparatus characterized in that the time can be shortened and the usability of an operator can be improved.

  In recent years, with the improvement in image quality of image forming apparatuses represented by color copiers, the state of the image forming unit of the apparatus has changed greatly, such as immediately after the power is turned on or left for a long time, in order to maintain the high image quality. When there is a factor to be obtained, it is indispensable to appropriately perform calibration control such as automatic gradation correction so that the density level of the image output is optimally corrected. FIG. 1 shows a color copying machine. The image output unit 1P is roughly divided into an image forming unit 10 (four stations a, b, c, and d are arranged in parallel, and the configuration is the same), a paper feeding unit 20, an intermediate transfer unit 30, and a fixing unit. The unit 40 and a control unit described later are included.

  Further, each unit will be described in detail. The image forming unit 10 is configured as described below. Photosensitive drums 11a, 11b, 11c, and 11d as image carriers are pivotally supported at their centers and are driven to rotate in the direction of the arrow. The primary chargers 12a, 12b, 12c, and 12d, optical systems 13a, 13b, 13c, and 13d, and developing devices 14a, 14b, 14c, and 14d are arranged in the rotation direction facing the outer peripheral surfaces of the photosensitive drums 11a to 11d. Yes. In the primary chargers 12a to 12d, charges of a uniform charge amount are given to the surfaces of the photosensitive drums 11a to 11d. Next, an optical latent image is formed on the photosensitive drums 11a to 11d by exposing the photosensitive drums 11a to 11d with light beams such as laser beams modulated by the optical systems 13a to 13d. Further, the electrostatic latent images are visualized by developing devices 14a to 14d that respectively store four color developers (toners) such as yellow, cyan, magenta, and black. On the downstream side of the image transfer areas Ta, Tb, Tc, and Td for transferring the visualized visible image to the intermediate transfer member, the photosensitive drums 11a to 11d are not transferred to the transfer material by the cleaning devices 15a, 15b, 15c, and 15d. The toner remaining on 11d is scraped off to clean the drum surface. By the process described above, image formation with each toner is sequentially performed.

  The paper feeding unit 20 includes cassettes 21a and b and a manual tray 27 for storing the recording material P, pickup rollers 22a and b and 26 for feeding the recording material P one by one from the cassette or from the manual tray, and each pickup roller. For feeding the recording material P sent out from the sheet to the registration roller pair 23 and the paper feeding guide 24 for conveying the recording material P to the registration roller, and for feeding the recording material P to the secondary transfer area Te in accordance with the image forming timing of the image forming unit. It consists of registration rollers 25a and 25b.

  The intermediate transfer unit 30 will be described in detail. The intermediate transfer belt 31 (for example, PET [polyethylene terephthalate] or PVdF [polyvinylidene fluoride] is used as its material) is energized by a driving roller 32 that transmits driving to the intermediate transfer belt 31 and a spring (not shown). As a result, the intermediate transfer belt 31 is wound around a tension roller 33 that applies appropriate tension, and a driven roller 34 that faces the secondary transfer region Te across the belt. Among these, a primary transfer plane A is formed between the driving roller 32 and the tension roller 33. The drive roller 32 is coated with rubber (urethane or chloroprene) having a thickness of several millimeters on the surface of the metal roller to prevent slippage with the belt. The drive roller 32 is rotationally driven by a pulse motor (not shown). Primary transfer blades 35 a to 35 d are disposed on the back of the intermediate transfer belt 31 in primary transfer regions Ta to Td where the photosensitive drums 11 a to 11 d and the intermediate transfer belt 31 face each other. A secondary transfer roller 36 is disposed opposite to the driven roller 34, and a secondary transfer region Te is formed by a nip with the intermediate transfer belt 31. The secondary transfer roller 36 is pressed with an appropriate pressure against the intermediate transfer member. A cleaning device 50 for cleaning the image forming surface of the intermediate transfer belt 31 is disposed on the intermediate transfer belt and downstream of the secondary transfer region Te. The cleaning device 50 includes a cleaner blade 51 (as a material, And a waste toner box 52 for storing waste toner.

  The fixing unit 40 includes a fixing roller 41a having a heat source such as a halogen heater inside, a 41b to which the roller is pressed (this roller may also have a heat source), and a transfer material to the nip portion of the roller pair. The guide 43 includes a guide 43 for guiding P, and an inner discharge roller 44 and an outer discharge roller 45 for guiding the transfer material P discharged from the roller pair to the outside of the apparatus.

  The control unit includes a control board 70 for controlling the operation of the mechanism in each unit, a motor drive board (not shown), and the like. Next, a description will be added in accordance with the operation of the apparatus.

  When the image forming operation start signal is issued, first, the transfer material P is sent out one by one from the cassette 21a by the pickup roller 22a. Then, the transfer material P is guided between the paper feed guides 24 by the paper feed roller pair 23 and conveyed to the registration rollers 25a and 25b. At that time, the registration roller is stopped, and the leading edge of the paper hits the nip portion. Thereafter, the registration roller starts rotating in accordance with the timing at which the image forming unit starts image formation. The rotation timing is set so that the transfer material P and the toner image primarily transferred from the image forming unit onto the intermediate transfer belt exactly coincide with each other in the secondary transfer region Te.

  On the other hand, in the image forming unit, when an image forming operation start signal is issued, a high voltage is applied to the toner image formed on the photosensitive drum 11d that is the most upstream in the rotation direction of the intermediate transfer belt 31 by the process described above. Further, primary transfer is performed on the intermediate transfer belt 31 in the primary transfer region Td by the primary transfer charger 35d. The primarily transferred toner image is conveyed to the next primary transfer region Tc. In this case, image formation is delayed by a time during which the toner image is conveyed between the image forming portions, and the next toner image is transferred with the resist aligned on the previous image. The same process is repeated thereafter, and the four color toner images are primarily transferred onto the intermediate transfer belt 31 after all.

  Thereafter, when the recording material P enters the secondary transfer region Te and contacts the intermediate transfer belt 31, a high voltage is applied to the secondary transfer roller 36 in accordance with the passing timing of the recording material P. Then, the four color toner images formed on the intermediate transfer belt by the process described above are transferred onto the surface of the recording material P. Thereafter, the recording material P is accurately guided to the fixing roller nip portion by the conveyance guide 43. The toner image is fixed on the paper surface by the heat of the roller pairs 41A and 41B and the pressure of the nip. Thereafter, the paper is conveyed by the inner and outer paper discharge rollers 44 and 45, and the paper is discharged outside the apparatus.

  FIG. 2 is a schematic view of the vicinity of the pattern image detecting means 60 for detecting the automatic gradation correction pattern image of the image forming apparatus in the conventional example. The detection means 60 is configured to include an LED and a PD, and among the plurality of photosensitive drums, located on the downstream side of the photosensitive drum 11a located on the most downstream side in the belt traveling direction, at a position Sa on the intermediate transfer belt 31, A gradation correction pattern image formed on the intermediate transfer belt is read. Correction is performed based on the gradation correction amount detected by the detection means 60. As shown in FIG. 3, the detection means 60 is disposed at the center of the intermediate transfer belt. Correction is performed based on the gradation correction amount detected by the detection means 60.

  FIG. 4 shows a pattern image for automatic gradation correction of an image forming apparatus in a conventional example. In the automatic tone correction pattern 401, patch rows of four primary colors of yellow, magenta, cyan, and black are continuously arranged. Further, as indicated by 402 and 403, patches of the respective colors are successively arranged from the highest density (d = 255) to the lowest density level (d = 0) from the beginning to the rear end of the patch. Since the density resolution of the image forming apparatus in the conventional example is 256 levels, 256 patches are arranged for each color. The detection unit 60 reads the patch image formed on the intermediate transfer belt, and obtains output signals S255 to S0 from the detection unit 60 for the density of each patch. Here, although not shown, the detection means 60 is a reflection type sensor, and the output signal is a signal obtained by converting the sensor output value into a digital value.

FIG. 5 describes parameter generation for correcting the output image density of the image forming apparatus based on the output signal of the automatic gradation correction patch in the conventional example. The characteristic curve 501 is generated by plotting the output signals S255 to S0 sampled in FIG. As is apparent from the curve, the characteristic curve 501 has a larger difference than the ideal density output curve 502, and with this characteristic curve, an image with the correct gradation can be obtained with respect to a document read by the image reading apparatus 1R. It is impossible to output. Therefore, a look-up table 503 that cancels the tone-density characteristic of the characteristic curve 501 is generated, and the input image density signal is corrected to the input image density signal at each density level. It becomes possible to approach. (For example, refer to Patent Document 1.)
JP 2000-238341 A

  However, since the image quality becomes high and the length of the above-described automatic gradation correction patch becomes long, it takes a lot of time to read the patch. Therefore, it is necessary to form an image immediately after starting up the image forming apparatus. This is a factor that impairs the operability for an unsatisfactory operator. In recent years, the color of office texts has increased, but in general color office documents have many opportunities to output images that do not necessarily require strict gradation reproducibility, such as graphs and color characters. For such an operator, a large amount of waiting time for automatic gradation correction every time the image forming apparatus is started up is a problem in an office that requires quickness. .

  Therefore, the present invention shows control for simplifying automatic gradation correction, and performs the simplified automatic gradation control only when it is determined that simplification is necessary, and uses the idle time of the image forming apparatus. By performing the original automatic gradation control again, the image forming apparatus can be quickly started up and the gradation of the image forming apparatus is not impaired.

  According to the present invention, it is possible to reduce the waiting time from the power-on to the start of printing without impairing the gradation as desired by the operator.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The image forming apparatus described in this embodiment is the same as that shown in FIG. The pattern image detection means for detecting the automatic gradation correction pattern image of the image forming apparatus described in the present embodiment is the same as that shown in FIGS. FIG. 6 shows an operation panel in the image forming apparatus described in the present embodiment. First, the operation panel has a hard key unit 601 for information to be input at a high frequency such as the number of prints, a magnification, and a color mode, and a display unit having a touch panel function for displaying information and inputting various setting modes. 602. In the display unit 602, the start-up mode in the image forming apparatus can be selected from two stages of quick and normal. When the normal mode is selected, the automatic chairman correction described in the conventional example is performed when the image forming apparatus is started up next time. In addition, when the quick mode is selected, the next automatic image forming apparatus startup will perform the simplified automatic gradation correction described in FIG. 7 and subsequent figures, and the image forming apparatus can be copied in a shorter time than the normal mode. It can be in a state. The operator determines the start-up mode according to the type of image to be output. In other words, when outputting an image that emphasizes gradation such as a photograph, the normal mode is selected, and the gradation of a document or the like is not regarded as important, and as soon as the image forming apparatus is started up, a little as soon as possible. Select Quick mode if you want to get output.

  FIG. 7 shows an automatic gradation correction pattern image of the image forming apparatus according to the present embodiment. In the automatic tone correction pattern 701, patch rows of four primary colors of yellow, magenta, cyan, and black are continuously arranged. In addition, as indicated by reference numeral 702, each color patch has four patches in total from the beginning to the end of the patch, the highest density (d = 255), the middle two density patches, and the lowest density level (d = 0). Are arranged continuously. In other words, the number of patches is reduced to 1/64 compared to the conventional example. The detection unit 60 reads the patch image formed on the intermediate transfer belt and obtains output signals S255, S169, S84, and S0 from the detection unit 60 for the density of each patch, as indicated by reference numeral 703.

  FIG. 8 illustrates parameter generation for correcting the output image density of the image forming apparatus based on the output signal of the simplified automatic gradation correction patch in the present embodiment. The characteristic approximate curve 801 is composed of a polygonal line in which the output signals S255, S169, S84, and S0 sampled in FIG. 8 are plotted and the intermediate density is linearly complemented. Next, a look-up table 803 that cancels the tone-density characteristic of the characteristic approximation curve 801 is generated, and the input image density signal at each density level is corrected to thereby approximate the intermediate density. Although not necessarily ideal, it becomes possible to bring the output density closer to the ideal output curve 802 to some extent.

  FIG. 9 is a flowchart describing a generation routine of the characteristic approximation curve 801 in the present embodiment. By applying any of the interpolation routines 906, 907, and 908 to all density levels from 902 to 905, the approximate output signal value for the unsampled density based on the output signal values of the two approximate sampling densities Can be easily obtained.

  FIG. 10 describes a schedule for executing the automatic gradation correction described in the present embodiment. After turning on the power in 1002, it is determined whether the warm-up mode shown in FIG. 6 is the quick mode or the normal mode (1003). In the normal mode, the automatic gradation correction described in the conventional example is performed at 1005, and a standby state is entered (1006). On the other hand, when the quick mode is selected, the simple automatic gradation correction described in the present embodiment is performed in 1004, and a standby state is set (1006). Next, in the standby state, it is determined whether the copy start key has been pressed and copying has started (1007). When copying does not start, the elapsed time (idle time) after entering the standby state is detected (not shown), but only simple automatic gradation correction is performed after power-on, and the idle time has reached a certain time. If it is determined that there is no other copy request frequency to the image forming apparatus (1009), the automatic gradation control described in the conventional example is performed using the idle time (1100). On the other hand, when the copying operation is being performed (1008) or when the idle time has not reached the predetermined time, it is determined that there are many print requests to the image forming apparatus, and the conventional example is described from the viewpoint of not waiting for the operator. Does not perform automatic gradation control. Further, although not particularly illustrated, when only the simple automatic gradation correction described in FIG. 10 is performed and the operator wants to output an image with more correctly corrected gradation even when the idle time has not been reached, FIG. A key for automatic gradation correction may be provided immediately from the operation panel described in FIG.

  In this embodiment, the operator determines whether or not to perform simple automatic gradation correction. For example, when the operator determines that he wants a reserved copy when the power is turned on, the operation screen is displayed. After issuing a warning that the gradation is somewhat degraded, it may be automatically determined to perform simple automatic gradation correction and start a reserved copy. Furthermore, only when it is determined that the copy mode of the reserved copy is monochrome, it is determined that strict gradation is not necessary, and it is automatically determined that the reserved copy starts after performing simple automatic gradation correction. good.

It is a diagram illustrating an image forming apparatus according to a conventional example and this embodiment. FIG. 6 is a schematic diagram in the vicinity of a sensor 60 that detects an automatic gradation correction pattern in a conventional example and in the present embodiment. It is a top view of the schematic shown in FIG. 2 in a conventional example and this embodiment. It is a figure explaining the automatic gradation correction patch in a prior art example. It is a figure explaining the gradation correction table in a prior art example. It is a figure explaining the operation panel in this embodiment. It is a figure explaining the gradation correction table in this embodiment. It is a figure explaining the characteristic characteristic curve approximated in this embodiment. It is a figure explaining the approximation routine of the characteristic approximation curve in this embodiment. It is a figure explaining the implementation timing of simple automatic gradation correction and automatic gradation correction in this embodiment.

Claims (9)

  Patch image forming means for forming a continuous patch array of a plurality of density levels by toner images by transferring a transfer material onto a transfer belt by electrophotography, and each patch of the patch array formed on the belt. In the image forming apparatus, the image forming apparatus is characterized by performing gradation control including a patch reading unit that reads the density of the image and a parameter determination unit that determines a density parameter of the image according to a read value of the patch by the patch reading unit. An image forming apparatus characterized in that the number of patches in a patch row differs depending on timing at which gradation control is performed.   2. The image forming apparatus according to claim 1, wherein the number of patches is the smallest during a warm-up operation after the image forming apparatus is powered on.   2. The image forming apparatus according to claim 1, wherein a density parameter corresponding to a patch having a density level that has not been imaged by gradation control is complemented based on another density parameter determined based on the patch. .   2. The image forming apparatus according to claim 1, wherein the density level patch that has not been formed in the gradation control is performed during an idle time during which the image forming apparatus does not process an image forming job.   The idle time in claim 4 is a time until the first image forming job is input after the image forming apparatus completes warm-up.   The image forming apparatus according to claim 1, further comprising selection means for an operator to select whether or not to switch the number of patches for gradation control.   The image forming apparatus according to claim 1, wherein whether or not to switch the number of patches for gradation control during warm-up is determined by the temperature of the fixing device at the start of warm-up.   The image forming apparatus according to claim 1, wherein whether or not to switch the number of patches for gradation control during warm-up is determined by whether or not a print reservation is made at the start of gradation control. 2. The image forming apparatus according to claim 1, wherein whether or not to switch the number of patches for gradation control during warm-up depends on data contents of image data reserved for printing at the start of gradation control.

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