JP2012220699A - Image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing method in which both processing speed satisfying productivity and thinning performance are achieved by determining the processing speed required for thinning processing, from a situation, and then switching thinning processing methods.SOLUTION: In an image forming method, a light beam is scanned on a photoreceptor in a main scanning direction and a sub-scanning direction in an image processing unit that includes a parameter acquisition section (200) for acquiring a parameter related to productivity; and a thinning processing operation switching section (220) for switching thinning processing (221, 222) in response to the parameter acquired in the parameter acquisition section. The image forming method includes: an image forming step of forming an image on the photoreceptor on the basis of image information subjected to thinning processing; a transferring step for transferring the image on the photoreceptor to a transfer medium; and a fixing step for fixing the image on the transfer medium, in the thinning processing switched to by the thinning processing operation switching section.

Description

  The present invention relates to an image forming apparatus using electrophotographic technology, and more particularly to an image forming method and apparatus for printing out an image based on print data sent from a host device on a predetermined recording medium.

  FIG. 7 is a longitudinal side view showing a schematic configuration of a laser beam printer in which electrophotographic technology as a conventional image forming apparatus is applied to a printer.

  The operation of this laser beam printer will be described below.

  The intensity of the laser beam from the scanner 701 is modulated from an image signal sent from a host computer (not shown) to form an electrostatic latent image on the photosensitive drum 702. On the other hand, the transfer material in the storage cassette 703 is taken out one by one by the paper feed roller 704, and the writing timing is adjusted by the registration rollers 705 and 706. Then, the toner image on the photosensitive drum 702 is transferred to the transfer material by the transfer roller 707. After that, a fixed image is formed through the conveyance belt 708, the fixing roller 709, and the pressure roller 710, and is stacked on the tray 713 by the paper discharge rollers 711 and 712.

  In such a normal printer, when a straight line in the main scanning direction is output, as shown in FIG. 8, the toner at the rear end in the sub-scanning direction of the line 802 recorded by the toner on the transfer material 801 scatters. The problem of disturbing the image occurred. It has been found that this problem occurs in a normal office environment and is more likely to occur especially at higher humidity.

  This is caused by the cause shown in FIG. Moisture in the transfer material 801 evaporates all at once due to a rapid temperature rise in the fixing process and compression by the upper and lower rollers (fixing roller 709 and pressure roller 710), and in the case of toners, water vapor escapes from the rear end where the force is weak. At this time, the toner also scatters.

  It is empirically known that this phenomenon is likely to occur when the linear width in the sub-scanning direction is about 100 μm to 1000 μm.

  In order to solve this problem, there is a technique in which the size of the image pattern included in the image information is determined, and a region corresponding to the rear end in the sub-scanning direction of the image pattern is thinned out at a predetermined ratio based on the determination. . The thinned portion is filled with toner splattering, so that the toner splattering at other locations is not easily produced. (For example, patent document 1).

Japanese Patent No. 3754836

  The above-described conventional example is realized by simple image processing, and a high printing speed can also be realized by using a large image pattern. However, increasing the image pattern reduces the pattern matching accuracy, and the range that can be thinned out depending on the image information has been reduced. Thus, because of the fixed processing method, there is a trade-off between processing speed and image quality.

  In recent years, as the output resolution of printers has increased in resolution and speed, to satisfy this, it is necessary to take a large image pattern and reduce the pattern matching accuracy, or reduce the productivity a little in order to be in time. It is gone.

  Therefore, an object of the present invention is to provide an image processing method that supports both the processing speed and the image quality by appropriately switching the thinning processing method according to the required processing speed.

  The configuration of the image forming method according to the present invention is an image forming method for scanning a light beam in a main scanning direction and a sub-scanning direction on a photoconductor, and a parameter acquisition unit (200) for acquiring parameters related to productivity. In the thinning process, the thinning process operation switching unit (220) for switching the thinning process (221, 222, 300) according to the parameter obtained by the parameter acquisition unit is switched by the thinning process operation switching unit. An image forming process for forming an image on the photoconductor based on the image information subjected to the thinning process, a transfer process for transferring the image on the photoconductor to the transfer medium, and a fixing for fixing the image on the transfer medium And a process.

  According to the image forming method of the present invention, by switching the thinning method according to the required processing speed, even if the processing time is short, the thinning is performed without causing a decrease in the printing speed, and the toner is roughly scattered. Can respond. Further, when there is a sufficient processing time, the effect on toner scattering can be enhanced by performing the thinning process in detail.

1 is a block diagram illustrating a configuration of an image forming apparatus. 2 is a block diagram illustrating a configuration of an image processing unit of the image forming apparatus. FIG. 3 is a flowchart illustrating a flow of an image processing operation in the image forming apparatus. It is a figure which shows the thinning pattern in an image forming apparatus. FIG. 3 is a diagram illustrating an outline of a thinning unit in the image forming apparatus. 3 is a diagram illustrating an image processing area in the image forming apparatus. FIG. 1 is a longitudinal sectional view illustrating a schematic configuration of a laser beam printer which is an image forming apparatus. FIG. 4 is a diagram illustrating a tailing phenomenon in the image forming apparatus. FIG. 3 is a simplified diagram illustrating a mechanism for generating a tailing phenomenon in an image forming apparatus. 6 is a correspondence table between a Print status and a request thinning-out processing speed in the image forming apparatus.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIG. 1, FIG. 2, and FIG. FIG. 1 is a block diagram showing a configuration of a laser beam printer which is an image forming apparatus according to Embodiment 1 of the present invention. Note that each processing unit shown in FIG. 1 is centrally controlled by a CPU in the image processing apparatus. Similarly, a program defining the processing content performed by each processing unit is stored in a state where it can be stored in a storage medium (HDD, flash memory, CD-ROM, DVD) in the image processing apparatus. Therefore, the CPU comprehensively controls the processing contents of the respective processing units by sequentially reading the programs stored in the storage medium.

  In FIG. 1, 10 is a laser beam printer (hereinafter referred to as a printer), and 20 is a host computer (hereinafter referred to as a host) which is a generation source of image information and print settings. The printer 10 includes an input / output I / F (interface) 30, a CPU (central processing unit) 40, an operation panel 41, a main memory 42, a bitmap memory 50, an image processing unit 60, and a printer engine 70.

  The input / output I / F 30 receives image information and print settings from the host 20 and transmits status information from the printer 10 to the host computer 20. A CPU (Central Processing Unit) 40 controls the entire printer 10. The operation panel 41 has operation buttons for performing various operations and a display unit for displaying various information, and is a panel for operating the printer 10.

  The main memory 42 is a memory that stores operation processing procedures, character patterns, thinning patterns, and the like of the CPU 40. The bitmap memory 50 is a memory capable of developing a dot image for one page to be printed. The image processing unit 60 performs image processing and has a characteristic configuration of the present invention, and details thereof will be described later. The printer engine 70 prints an image on a transfer material.

  FIG. 2 is a diagram illustrating an image processing method of the image processing unit 60. The parameter acquisition unit 200 acquires parameters related to productivity. The page position, the print job scheduling status, the rendering setting, the output resolution setting, the paper size, the paper orientation, and the like.

  The thinning performance calculation unit 210 obtains the processing speed / processing priority required for the thinning process from these parameters. FIG. 10 shows an example in which the processing speed required for thinning out is determined from several parameters.

  When the host issues a new PrintJOB in response to a user instruction, if the printer's PrintJOB is congested, the page processing of the new PrintJOB does not need to be urgent and the processing speed requirement for thinning is low. On the other hand, in the case of TopJOB with no other PrintJOB, if it is TopPage processing, the processing speed requirement for thinning processing is high. If the output resolution setting is 1200 dpi, the number of processing pixels is large, so that the demand for processing speed is further increased. In this way, the processing speed requirement for thinning changes according to the setting and situation.

  Then, based on the result output by the thinning performance calculation unit 210, the thinning processing operation switching unit 220 switches and operates thinning modules having different processing speeds. The thinning processing operation switching unit 220 has a plurality of thinning modules such as the thinning module 221 and the thinning module 222, and the processing speed and the thinning performance are different from each other.

  Although the result of the thinning performance calculation unit 210 is used here, a speed priority / image quality priority selection button may be prepared on the operation panel 41 and the thinning module to be used may be switched depending on the state. .

  As described above, an image processing method that supports both performance and image quality is provided by switching the thinning method according to the required processing speed.

<Embodiment 2>
In the second embodiment, only differences from the first embodiment are described.

  In the first embodiment, the thinning modules having different processing speeds are switched and operated. In contrast, the second embodiment uses a variable speed thinning module 300 that can change the thinning processing speed by a parameter in the same thinning module. Hereinafter, the variable speed thinning module 300 will be described. The thinning processing operation switching unit 220 changes parameters related to the processing speed of the variable speed thinning module 300 in accordance with the processing speed / processing priority calculated from the thinning performance calculation unit 210.

  FIG. 3 is a flowchart of the variable speed thinning module 300. Briefly, it is a thinning module that can change the number of execution commands and change the processing speed by switching the thinning processing unit as shown in Fig. 5. This will be described in detail with reference to FIG.

  A setting value 310 is given to the variable speed thinning module 300. The thinning pattern M_Pt is stored in the main memory 42. Here, FIGS. 4A to 4D are given as an example. Although a large pattern is stored in the main scanning direction, only the minimum repetitive pattern may be stored, and the pattern may be repeatedly developed for the required size when used.

  Note that, as shown in FIG. 4, the thinning pattern is assumed to hold a value indicating the pattern size and the upper / lower limit line width to be thinned.

  The thinning unit setting M_unit indicates the main scanning width of the unit for thinning. The image pattern determination unit setting P_unit indicates a main scanning width of a unit for performing pattern determination for specifying a thinned portion.

  Reference numeral 320 denotes a coordinate system with respect to the paper transport direction of an image for one page developed in the bitmap memory 50. D (X, Y) represents dot information at the coordinate position (X, Y). Hereinafter, the X axis may be expressed as the main scanning direction and the Y axis may be expressed as the sub scanning direction.

  Next, the flow will be described.

  First, in S3001, data initialization is performed. The coordinates are cleared so that the image pattern to be thinned out is from the downstream side in the paper conveyance direction. Also, the black line counter used for black line width determination is cleared. Also, parameters related to the thinning pattern set in 310 are read.

  In step S3002, a thinning pattern mask process is performed according to the thinning unit setting. Specifically, the portion exceeding the thinning unit stored in the thinned-out pattern is repainted with black dots.

  Next, in S3003, it is determined whether or not the dots corresponding to the image pattern determination unit P_unit at the current coordinate position D (X, Y) are all black.

  If it is determined that the color is all black, the process proceeds to S3004, and the black line counter is incremented by one. If it is determined that it is not all black, the process proceeds to S3005, and thinning is performed according to the counter value of the black line counter. The thinning method will be described later with reference to FIG.

  In S3006, it is determined whether or not the dots corresponding to the image pattern determination unit P_unit at the current coordinate position D (X, Y) are all white. If it is determined that all white, it proceeds to S3007 and clears the black line counter. If it is determined that it is not all white, the process proceeds to S3008, and the black line counter is changed to the upper limit of the thinning line width. As a result, the thinning process is not performed until all white comes.

  When the determination of the image pattern at the current coordinate position D (X, Y) is completed, the process proceeds to S3009, where it is determined whether or not the processing has been completed up to the first line. If not completed, the coordinate position in the Y-axis direction is advanced and the image pattern determination is repeated. When the first line is completed, the process proceeds to S3005, and thinning is performed according to the current state of the black line counter.

  In step S3007, the black line counter is cleared.

  In S3010, it is determined whether any unprocessed portions remain in the X-axis direction. If an unprocessed portion corresponding to the thinning unit setting M_unit remains, it moves in the X-axis direction, and in S3011 moves to the last end line of the Y-axis. If there is no unprocessed part, the process ends.

  Next, how the thinning is applied to the input image will be described with reference to FIG. Reference numeral 600 denotes a setting example of the variable speed thinning module 300, which corresponds to S3001.

  Reference numeral 610 denotes that a portion outside the thinning unit setting in the main scanning direction is masked with black for the thinning pattern PT01. This corresponds to S3002.

  Reference numeral 620 denotes an example in which an input image is referred to in units of image pattern determination and black lines are counted. In the case of the input image shown here, the count is cleared with all white (corresponding to S3007), and after the black line continues for 3 lines, other than all black comes, so it is determined that the black line width is 3 lines.

  In 630, since the black line width determined in 620 is within the lower limit / upper limit line width set to 600, AND processing between the input image and the thinned pattern image after masking is performed within the range of black line width -1. This shows the situation where decimation is performed. This part shows the internal operation of S3005 not described in detail in FIG.

  As described above, it is possible to realize a thinning process having a variable processing speed. As a result, it is possible to realize thinning processing that supports both performance and image quality by switching operations according to the required processing speed.

<Other examples>
The object of the present invention can also be achieved by a computer (or CPU or MPU) of a system or apparatus reading out and executing the program code from a storage medium storing the program code for realizing the above-described processes. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment. Therefore, this program code and a computer-readable storage medium storing the program code also constitute one aspect of the present invention.

  As a storage medium for supplying the program code, for example, a floppy (registered trademark) disk, HDD, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM, or the like is used. be able to.

  Further, when the program code read out by the computer is executed and the functions of the above-described embodiments are realized by the execution of the program code, it constitutes one aspect of the present invention.

10 Image forming device (laser beam printer)
20 Host computer 30 Input / output I / F (interface)
40 CPU (Central Processing Unit)
41 Operation Panel 42 Main Memory 50 Bitmap Memory 60 Image Processing Unit 70 Printer Engine

Claims (10)

An image forming method for scanning a light beam in a main scanning direction and a sub-scanning direction on a photoreceptor, a parameter acquisition unit (200) for acquiring parameters related to productivity, and the parameters obtained by the parameter acquisition unit The thinning processing operation switching unit (220) for switching the thinning processing (221, 222, 300) according to the image processing is performed on the basis of the image information subjected to the thinning processing in the thinning processing switched by the thinning processing operation switching unit. An image forming process comprising: an image forming process for forming an image on a photoconductor; a transfer process for transferring an image on the photoconductor to a transfer medium; and a fixing process for fixing the image on the transfer medium. Method. The thinning-out process includes a determination step (620) for determining an image pattern included in the image information, and a predetermined ratio in the main scanning direction is thinned out at the rear end portion in the sub-scanning direction of the image pattern based on the determination in the determination step. The image forming method according to claim 1, further comprising a thinning step (630). The image forming method according to claim 1, wherein the parameter is information related to the number of processing pixels (FIG. 10) of paper size / layout setting / output resolution setting. The image forming method according to claim 1, wherein the parameter is information (FIG. 10) necessary for calculating a print job scheduling status and a time taken to print a page position. The image forming method according to claim 1, wherein the parameter is a setting indicating image quality priority / speed priority. The image forming method according to claim 1, wherein the thinning operation switching unit selects a thinning processing operation (221, 222, 300) having the highest image quality effect while satisfying productivity. The image forming method according to claim 1, wherein the thinning operation switching unit switches between a plurality of thinning processing modules (221, 222). 2. The image forming method according to claim 1, wherein the thinning operation switching unit switches and uses a parameter related to the speed of the thinning processing module (300) whose processing speed is variable. 3. The image forming method according to claim 2, wherein in the thinning process, the size of the image pattern is variable in the determination step. In the thinning-out process, the thinning-out unit is variable when thinning out a predetermined ratio in the main scanning direction at the rear end in the sub-scanning direction of the image pattern based on the determination in the determination process. The image forming method according to claim 2.