JP3754836B2 - Image forming method and apparatus, and storage medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
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.
[0002]
[Prior art]
FIG. 12 is a longitudinal side view showing a schematic configuration of a laser beam printer in which electrophotographic technology, which is a conventional image forming apparatus, is applied to a printer.
[0003]
The operation of this laser beam printer will be described below.
[0004]
The intensity of the laser beam from the scanner 1201 is modulated from an image signal sent from a host computer (not shown) to form an electrostatic latent image on the photosensitive drum 1202.
[0005]
On the other hand, the transfer material in the storage cassette 1203 is taken out one by one by the paper feed roller 1204 and the writing timing is adjusted by the registration rollers 1205 and 1206. Then, the toner image on the photosensitive drum 1202 is transferred to the transfer material by the transfer roller 1207. After that, a permanent fixed image is obtained through the conveyance belt 1208, the fixing roller 1209a, and the pressure roller 1209b, and is stacked on the tray 1212 by the paper discharge rollers 1210 and 1211.
[0006]
In addition, conventional laser beam printers that have an energy saving mode for saving toner consumption have appeared. In this type of printer, as described in Japanese Patent Publication No. 61-60480, the dot width of one pixel in the image information is narrowed to reduce the amount of toner consumed, or Japanese Patent Publication No. 9-30042 is disclosed. As described in the above, toner consumption is suppressed by thinning out the image area at a predetermined rate.
[0007]
[Problems to be solved by the invention]
However, the above-described conventional thinning-out method for a printer having an energy saving mode that saves toner consumption causes a reduction in image quality, and if a complicated processing method is employed, the memory area of the printer is compressed. Or a decrease in print speed.
[0008]
In a normal printer, when a straight line in the main scanning direction is output as an image, as shown in FIG. 13, the toner at the rear end in the sub-scanning direction of the line 1302 recorded with toner on the transfer material 1301 is scattered. The problem of disturbing the image occurred.
[0009]
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. That is, the moisture in the transfer material 1301 evaporates explosively due to a rapid temperature rise in the fixing process and compression by the upper and lower rollers (the fixing roller 1209a and the pressure roller 1209b). Get out of. At this time, the toner also scatters.
[0010]
Further, 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.
[0011]
The present invention has been made in view of such problems of the prior art described above, it is an purpose of that is, by a simple image processing, reduce the consumption amount of toner without disturbing the image It is an object of the present invention to provide an image forming method and apparatus and a storage medium that can be used.
[0016]
[Means for Solving the Problems]
To achieve the above object, an image forming method according to claim 1 is on the photosensitive member to an image forming method of scanning a light beam in the main scanning direction and the sub-scanning direction, the image pattern included in the image information Based on the determination step for determining the size , and the determination in the determination step, the thinning step for thinning out the area corresponding to the rear end of the image pattern in the sub-scanning direction at a predetermined rate, and the thinning process in the thinning step. includes an image forming step of forming an image on a photosensitive body based on image information, a transfer step of transferring the image on said photosensitive member to a transfer medium, and a fixing step of fixing the image on the transfer medium It is characterized by that.
The image forming apparatus according to claim 5 is an image forming apparatus that scans a light beam in a main scanning direction and a sub scanning direction on a photosensitive member, and corresponds to a rear end portion of an image pattern included in image information in a sub scanning direction. Thinning means for thinning out the area to be processed at a predetermined rate, determination means for determining execution of thinning processing by the thinning means based on the size of the image pattern, and photosensitivity based on image information subjected to thinning processing by the thinning means. An image forming unit that forms an image on a body, a transfer unit that transfers an image on the photosensitive member to a transfer medium, and a fixing unit that fixes the image on the transfer medium.
A storage medium according to claim 9 is a storage medium storing a control program for controlling an image forming apparatus that scans a light beam in a main scanning direction and a sub-scanning direction on a photosensitive member, and the control program stores image information. The size of the image pattern included in the image pattern is determined, and based on the determination, the area corresponding to the rear end portion in the sub-scanning direction of the image pattern is thinned out at a predetermined rate, and based on the image information subjected to the thinning process. And a control module for controlling to form an image on the photoconductor, transfer the image on the photoconductor to a transfer medium, and fix the image on the transfer medium.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS.
[0033]
(First embodiment)
First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a configuration of a laser beam printer which is an image forming apparatus according to a first embodiment of the present invention. In FIG. 1, reference numeral 10 denotes a laser beam printer (hereinafter referred to as a printer), A host computer 20 is an image information generation source.
[0034]
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.
[0035]
The input / output I / F 30 receives image information from the host computer 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.
[0036]
The main memory 42 is a memory that stores operation processing procedures, character 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.
[0037]
2 and 3 are diagrams illustrating an image processing method of the image processing unit 60. In FIG. 2, 1a represents the presence or absence of image information on one dot line in the main scanning direction, and the convex portion is printed. The part and the concave part represent the non-printing part. 1 represents the length of one dot line in the main scanning direction, and 1b1 to 1b5 represent patterns that are actually printed. Further, w represents a reference length of one dot line in the main scanning direction for performing image processing of the present invention.
[0038]
In FIG. 3, 2a1 to 2a6 indicate the presence or absence of image information on one dot line in the main scanning direction, similarly to 1a in FIG. 2, 2b is a pattern to be actually printed, and w is the image processing of the present invention. The reference length of one dot line in the main scanning direction to be performed, s, indicates an area where thinning processing is performed.
[0039]
FIG. 4 is a flowchart showing the operation of the image processing unit 60 and the operation procedure of FIGS. A series of operations will be described with reference to FIGS. 4 and 1 to 3.
[0040]
The image information sent from the host computer 20 in FIG. 1 is converted into image data in units of one dot by the bitmap memory 50 in the printer 10, and the converted image is sent to the image processing unit 60. The image processing unit 60 performs logical calculation on the sent image information according to the flowchart of FIG.
[0041]
That is, in FIG. 4, first, one dot line length is set in step S400, and in the next step S401, the image data length a for one dot in the main scanning direction is larger than the reference length w of one dot line in the main scanning direction. It is also determined whether or not it is too long. If the image data length a is longer than the reference length w, it is determined in the next step S402 whether or not the determination operation in step S401 has been repeated six times in the sub-scanning direction. If the determination operation in step S401 is not repeated six times in the sub-scanning direction, the process returns to step S401. If the determination operation in step S401 is repeated six times in the sub-scanning direction, the process proceeds to the next step S403. . That is, in FIG. 2, the image data of 1b2 and 1b5 proceeds to the next determination process, but 1b1, 1b3, and 1b4 are sent to the image composition unit without performing image processing. Only the data that has cleared the criterion six times, that is, only the image data of the image area s in FIG. 3 is sent to the thinning-out processing unit in step S403.
[0042]
On the other hand, if the image data length a is not longer than the reference length w in step S401, the process skips step S402 and step S403 and proceeds to step S404.
[0043]
In step S404, the image subjected to the image conversion in step S403 and the image not subjected to the image conversion are sent to the image combining unit, and both images are combined in the image combining unit to form one image. In the next step S405, the image synthesized in step S404 is sent to the image output unit. The image output unit prints and outputs the image on the transfer material, and the processing operation ends.
[0044]
When the method according to this embodiment is applied to a laser beam printer having a resolution of 600 dpi, the reference length w is about 100 dots, and the number of repetition determinations in the sub-scanning direction is about 6 to 8 (dots). Good results have been obtained.
[0045]
(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS.
[0046]
FIG. 5 is a diagram showing the image information extracted in the first embodiment. In FIG. 5, 5a represents the presence or absence of image information on one dot line in the main scanning direction, and the convex portion is printed. And the concave portion represents a non-printing portion. Reference numeral 5b denotes an image pattern obtained by printing the information 5a.
[0047]
FIG. 6 is a diagram showing the image information after thinning out the image information of 5a, and similarly to FIG. 5, 6a represents the presence or absence of image information on one dot line in the main scanning direction, and its convex portion Represents a printing portion, and a concave portion represents a non-printing portion. Reference numeral 6b denotes an image pattern obtained by printing the information of 6a.
[0048]
When normal image processing is performed, the image information 5a becomes a straight line having a width of 6 dots as in 5b. In the present embodiment, the image information 5a is thinned out at equal intervals for each line, and the thinned-out portions are shifted in the sub-scanning direction so that the thinned-out portions are not overlapped continuously in the sub-scanning direction. The pattern actually printed by this processing is 6b.
[0049]
FIG. 7 is an enlarged view of the thinned portion 6b. In FIG. 7, reference numeral 71 denotes a pattern in which image data is restored as it is, and 72 denotes a case where printing is performed using electrophotography. Comparing 6b and 5b, the defect in the image is conspicuous in 6b and the image quality is lowered, but when the image is actually output using an electrophotographic technique such as a laser beam printer, it is thinned out as 72. The portion is filled with the scattering of the surrounding toner, and the image is almost the same as 5b.
[0050]
If the thinning-out ratio is less than 5% of the extracted image, it has been experimentally obtained that the image quality is hardly deteriorated. In the present embodiment, the specific number of dots to be thinned out is not described. However, in the case of a 600 dpi printer, in the case of one dot per 10 dots and thinned every other dot in the sub-scanning direction. In addition, it is possible to obtain a good result that toner consumption can be suppressed to the maximum without degrading image quality.
[0051]
(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS.
[0052]
FIG. 8 is a diagram showing the image information after the image information extracted in the first embodiment is thinned out. In FIG. 8, 8a represents the presence / absence of image information on one dot line in the main scanning direction. The convex portion represents a printing portion, and the concave portion represents a non-printing portion. Reference numeral 8b denotes an image pattern obtained by printing the information 8a.
[0053]
FIG. 9 is a schematic diagram of the tailing phenomenon. In FIG. 9, reference numeral 91 denotes an image obtained by cutting out a horizontal rectangular pattern in the main scanning direction by 10 or more dots from the lower end of the image and 10 or more dots in the main scanning direction. Reference numeral 912 denotes an area in which the likelihood of the tailing phenomenon is divided in the image 91, and the ease of the tailing phenomenon is small , large , and medium in order. a91 represents an image after the tailing phenomenon of the image 91 has occurred, and 911d represents that 911 images have been tailed. Reference numeral 92 denotes an image obtained by performing image processing on an image having the same shape and size as the image 91 according to the present embodiment. a92 represents an image after the tailing phenomenon of the image 92 has occurred, and 92d represents toner scattered in the thinning portion.
[0054]
In this embodiment, only the countermeasure against the tailing phenomenon is focused, and the image extracted in the first embodiment is thinned out so that only the trailing 3 dots in the sub-scanning direction have a width of 1 dot, such as 8a. . The thinning interval in the main scanning direction is preferably 1 dot or 2 dots with respect to 10 dots.
[0055]
In the image 91, the tailing phenomenon itself is caused by the explosive generation of water vapor at a portion where the binding force between the toners or the binding force with the transfer material is small, as in 911. Will be scattered at the rear edge of the image. However, by creating an image like 92, the phenomenon can be prevented beforehand by creating a water vapor path. Further, due to the scattering of the toner around the thinning portion, the image defect at the thinning portion can be filled to some extent as in 92d.
[0056]
FIG. 10 is a diagram illustrating a relationship between an image pattern subjected to image processing, a tailing phenomenon, and image quality in the present embodiment. This is a diagram in which, with a 600 dpi laser beam printer, the main scanning direction is thinned out at a rate of 1 dot per 10 dots and the thinning length in the sub-scanning direction is changed from the rear end in the sub-scanning direction of the image pattern. As is apparent from the figure, the highest image quality can be maintained when thinning out with a width of 3 dots from the sub-scanning direction.
[0057]
In this embodiment, image processing is performed for only 3 dots from the rear end in the sub-scanning direction of the image extracted in the first embodiment, but the tailing phenomenon has a width of 100 μm to 1000 μm in the sub-scanning direction. Since this is likely to occur, the area where image processing is performed is limited by the length in the sub-scanning direction, and the image processing described in the second embodiment can be performed except for the tail image processing portion. It can be considered as an example of form development.
[0058]
(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIGS.
[0059]
In the first to third embodiments described above, the image processing is performed by the image processing unit 60 in FIG. 1, but the thinning processing causes a considerable decrease in image quality, and the tailing phenomenon is related. It is a phenomenon that occurs only in a specific environment. Therefore, in the present embodiment, a selection mode is provided for determining whether or not image processing can be performed on the operation panel 41 in FIG. That is, providing the selection mode on the operation panel 41 gives the user the right to select whether or not to perform image processing. This makes it possible to provide an image that suits the user's taste.
[0060]
FIG. 11 is a flowchart showing a flow of operations in a selection mode for determining whether image processing is possible.
[0061]
In the figure, first, in step S1101, it is determined whether or not to perform image processing. When image processing is performed, one dot line length is set in step S1102, and in the next step S1103, the image data length a for one dot in the main scanning direction is the reference length w of one dot line in the main scanning direction. It is determined whether it is longer than or not. If the image data length a is longer than the reference length w, it is determined in the next step S1104 whether or not the determination operation in step S1103 has been repeated six times in the sub-scanning direction. If the determination operation in step S1103 is not repeated six times in the sub-scanning direction, the process returns to step S1103. If the determination operation in step S1103 is repeated six times in the sub-scanning direction, the process proceeds to the next step S1104. . That is, in FIG. 2, the image data of 1b2 and 1b5 proceeds to the next determination process, but 1b1, 1b3, and 1b4 are sent to the image composition unit without performing image processing. Only the data that has cleared the discrimination criterion six times, that is, only the image data of the image area s in FIG. 3 is sent to the thinning processing unit in step S1105.
[0062]
On the other hand, if the image data length a is not longer than the reference length w in step S1103, the process skips step S1104 and step S1105 and proceeds to step S1106.
[0063]
In step S1106, the image converted in step S1103 and the image that has not been image-converted are sent to the image combining unit, and both images are combined in this image combining unit to form one image. In step S1107, the image synthesized in step S1106 is sent to the image output unit. The image output unit prints and outputs the image on the transfer material, and then ends the processing operation.
[0064]
On the other hand, if image processing is not performed in step S1101, the process skips steps S1102 to S1106, proceeds to step S1107, and outputs an image.
[0065]
In this embodiment, only a selection mode for determining whether or not to perform image processing is provided, but a plurality of modes such as a toner consumption saving mode and a tailing phenomenon countermeasure mode are provided to perform processing suitable for the application. This is also considered as an example of development of this embodiment.
[0066]
【The invention's effect】
According to the onset bright As described above in detail, it is possible to save the amount of toner without reducing the image quality, also it is possible to suppress the occurrence of trailing phenomenon, further preference of the user It is possible to provide the best image according to the environment.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an image forming apparatus according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a reference length of one dot line in the image forming apparatus according to the first embodiment of the present invention.
FIG. 3 is a diagram showing an image processing area in the image forming apparatus according to the first embodiment of the present invention.
FIG. 4 is a flowchart showing a flow of an image processing operation in the image forming apparatus according to the first embodiment of the present invention.
FIG. 5 is a diagram showing image information before image processing in an image forming apparatus according to a second embodiment of the present invention.
FIG. 6 is a diagram showing image information after image processing in an image forming apparatus according to a second embodiment of the present invention.
FIG. 7 is a diagram illustrating toner scattering in a thinning area in an image forming apparatus according to a second embodiment of the present invention.
FIG. 8 is a diagram showing image information after image processing in an image forming apparatus according to a third embodiment of the present invention.
FIG. 9 is a schematic diagram of a tailing phenomenon in an image forming apparatus according to a third embodiment of the present invention.
FIG. 10 is a diagram illustrating image tailing and image quality after image processing in an image forming apparatus according to a third embodiment of the present invention.
FIG. 11 is a flowchart illustrating a flow of an image processing operation in an image forming apparatus according to a fourth embodiment of the present invention.
FIG. 12 is a longitudinal sectional view showing a schematic configuration of a laser beam printer as a conventional image forming apparatus.
FIG. 13 is a diagram illustrating a tailing phenomenon in a conventional image forming apparatus.
FIG. 14 is a simplified diagram illustrating a trailing phenomenon occurrence mechanism in a conventional image forming apparatus.
[Explanation of symbols]
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 (12)

An image forming method of scanning a light beam on a photoconductor in a main scanning direction and a sub-scanning direction,
A determination step of determining the size of the image pattern included in the image information;
Based on the determination of the determination step, a thinning step of thinning out a region corresponding to the rear end portion in the sub-scanning direction of the image pattern at a predetermined rate;
An image forming step of forming an image on the photoreceptor based on the image information subjected to the thinning process in the thinning step;
A transfer step of transferring an image on the photoreceptor to a transfer medium;
Image forming method characterized by having a fixing step of fixing the image on the transfer medium.   The image forming method according to claim 1, wherein the determination step determines whether to perform a thinning process based on a length in the main scanning direction and a length in the sub scanning direction of the image pattern.   2. The image forming method according to claim 1, wherein in the thinning step, the thinning position is made variable for each line so that the thinning position does not continue in the sub-scanning direction.   The image forming method according to claim 1, further comprising a selection step of selecting whether or not the thinning step can be executed. An image forming apparatus that scans a light beam on a photoconductor in a main scanning direction and a sub-scanning direction,
Thinning means for thinning out a region corresponding to the rear end in the sub-scanning direction of the image pattern included in the image information at a predetermined rate;
Determining means for determining execution of thinning processing by the thinning means according to the size of the image pattern;
An image forming means for forming an image on the photosensitive member based on the image information subjected to the thinning process in the thinning means;
Transfer means for transferring an image on the photoreceptor to a transfer medium;
An image forming apparatus, comprising a fixing unit for fixing the image on the transfer medium.   The image forming apparatus according to claim 5, wherein the determination unit determines whether to perform a thinning process based on a length in the main scanning direction and a length in the sub scanning direction of the image pattern.   6. The image forming apparatus according to claim 5, wherein in the thinning unit, the thinning position is variable for each line so that the thinning position is not continuous in the sub-scanning direction.   6. The image forming apparatus according to claim 5, further comprising a selection unit that selects whether or not the thinning unit can be executed. A light beam on the photosensitive member to a storage medium storing a control program for controlling an image forming apparatus for scanning in the main scanning direction and the sub-scanning direction, wherein the control program, the size of the image pattern included in the image information Based on the determination, an area corresponding to the rear end portion in the sub-scanning direction of the image pattern is thinned out at a predetermined ratio, and an image is formed on the photoconductor based on the image information subjected to the thinning process. A storage medium comprising a control module for controlling to transfer an image on the photosensitive member to a transfer medium and fix the image on the transfer medium.   The storage medium according to claim 9, wherein the determination process determines execution of a thinning process based on a length of the image pattern in a main scanning direction and a length in a sub scanning direction.   10. The storage medium according to claim 9, wherein in the thinning process, the thinning position is made variable for each line so that the thinning position does not continue in the sub-scanning direction.   The storage medium according to claim 9, wherein the control program includes a control module for controlling to select whether or not to execute the thinning process.

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