CN100438552C - Image forming apparatus and image forming method - Google Patents

Abstract

When copying an object that has faded markings of color fadable toner and is printed with the color fadable toner, a threshold value changing key is displayed on a liquid crystal display of an operation panel to be pressed down. A main CPU sets a threshold value 1 a and a threshold value 2 a in an image processing unit upon detecting the threshold value changing key displayed on the liquid crystal display of the operation panel via a touch panel. The image processing unit eliminates a background image by using the set threshold value 1 a and threshold value 2 a, thereby providing dark printing with an excellent image.

Description

Image forming apparatus and image forming method

technical field

The present invention relates to an image forming apparatus (such as a copier, a printer, a facsimile, or a multifunctional peripheral integrated copier, a printer, and a facsimile) and an image forming method.

Background technique

In general, printing on the unprinted side of paper, double-sided printing, and printing on recycled paper have become common due to increased environmental awareness (as seen in conservation activities for forests as paper resources), which can reduce The amount of paper used by an image forming apparatus such as a copier, a printer, a facsimile, or a multifunction peripheral-integrated copier, a printer, and a facsimile.

In addition, there are known methods of recycling paper, that is, methods of mechanically or chemically separating the toner (also known as toner) on the paper from the paper and when heat, light, or chemicals are applied A method using a fadeable toner (for example, USP No. 5,605,777 and Japanese Patent Application Laid-Open Publication No. 5-191607).

In the above method of reducing the amount of paper used for printing, the latter method of separating toner on the paper or using fadeable toner compared with the former method of printing on the unprinted side of the paper or double-sided printing, It has the effect of saving paper more effectively.

The above method of separating the toner on the paper damages the paper by peeling the toner from the paper, reducing the durability of the toner after printing on the paper, is stripped on every page, so this method is not efficient. Also, the method of using chemicals has the problem of the process of handling the chemicals.

The method of using fadeable toner is more effective than the method of separating the toner from the paper. Although the color of the toner can be erased, the ingredients other than the coloring ingredients will remain. For this reason, slight print traces are left, and the process of printing → erasing → printing → erasing is repeated, producing many trace layers that darken the surface. Also, to ensure an effective fading function, set the image density lower than when using general fast toner.

Due to the above two problems, when copying paper printed with fadeable toner (the toner has been wiped off one or more times before printing), the background with residual traces is recognized as an "image" and read After taking it as image processing, the actual printing on recycled paper is usually very light due to its low density, so the actual printing part is recognized as light image printing. Then, when the printed paper is copied, portions of the image on the paper become lighter and erased portions on the background of the paper appear on the copied paper, making it difficult to read the copy. As for facsimile, due to the image in the case of copying described above, ideal images cannot be transmitted, and in addition, ideal images cannot be obtained even with a scanner.

In particular, in order to improve these problems, fadeable toner can be used, and when the image forming apparatus has an image processing adjustment function, operations such as adjusting the background and density of paper, or changing the range correction strength can be performed.

However, multiple steps are required in order to perform these operations, which makes it more complicated and needs to go through these steps whenever copying, facsimile, or scanning functions are used, thus greatly reducing efficiency. Also, there is no way to obtain an ideal image by using an image forming apparatus without using an image processing adjustment function that enables a user to perform variable adjustment.

Contents of the invention

An object of the present invention is to provide an image forming apparatus and an image forming method using a fadeable toner, which provide an effective image processing adjustment function.

According to an aspect of the present invention, there is provided an image forming apparatus including: reading means for reading an image on an object; image processing means for processing the image read by the reading means; storage means for Threshold information different from that used in general image formation which is stored in advance for use in image processing for fadeable image formation with respect to the image processing apparatus; indicating means for indicating threshold information for image processing by the image processing apparatus; and Control means for, when the threshold information is indicated by the indicating means, controlling reading of the indicated threshold information from the storage means and setting of the information in the image processing means.

According to another aspect of the present invention, there is provided an image processing method including: reading an image on an object; processing the image read by the reading step; Threshold information used in different from that used in general image processing; threshold information indicating image processing for a processing step; and when the threshold information is indicated, reading the indicated threshold information from pre-stored threshold information and Information is set in the processing step.

Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objects and advantages of an aspect of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.

Description of drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate the embodiments of the invention and together with the general description above and the specific description of the embodiments below, serve to explain the principles of one aspect of the invention.

FIG. 1 is a block diagram showing a schematic structure of an image forming apparatus according to an embodiment of the present invention;

FIG. 2 is a view showing an example of an object printed using conventional toner;

Figure 3 is a graph showing concentration histogram data (concentration histogram data) for the subject in Figure 2;

4 is a graph showing density frequency curve data after image processing for copying an object printed using a conventional toner;

FIG. 5 is a view showing an example of an object printed using fadeable toner;

6 is a view showing an example of an image after erasing the color of an image printed using a fadeable toner;

FIG. 7 is a view showing an example of an object printed with an eradicable toner on a faded trace remaining on a target paper after fading;

FIG. 8 is a graph showing density frequency curve data of the image in FIG. 7;

FIG. 9 is a view showing an image processing result of the image in FIG. 7;

FIG. 10 is a graph showing an example of setting thresholds 1a and 2a different from thresholds 1 and 2;

FIG. 11 is a view showing an example of an image using threshold 1a and threshold 2a;

12 is a block diagram showing a schematic configuration of a color image forming apparatus related to a modification of the present invention;

FIG. 13 is a view showing an example of the structure of a control panel;

14 is a view showing an example of a display of a liquid crystal display unit;

FIG. 15 is a view showing another example of a display of a liquid crystal display unit.

Detailed ways

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a schematic structure of an image forming apparatus according to an embodiment of the present invention. This image forming apparatus includes a main control unit 1 , a scanning unit 2 , a printing unit 3 , and an operation panel 4 .

Main control unit 1 comprises: main CPU 10, is used for carrying out the integral control of equipment; ROM 11, wherein stores control program etc.; RAM 12, is used for temporarily storing data; Used to process images by setting density thresholds.

The scanning unit 2 is a reading device for reading an image on an object (usually paper).

The printing unit 3 is an image forming device for forming an image on paper based on the image data processed at the image processing unit 13 . For example, the printing unit 3 includes: a photoreceptor as an image carrier; a laser exposure device for forming an electrostatic latent image on the photoreceptor; a developing device for developing by supplying toner as a developer; and a transfer device , for transferring the toner image to paper.

The operation panel 4 includes: a liquid crystal display 42, which has a touch panel 41; a plurality of operation keys 43; a panel CPU 44, connected with the liquid crystal display 42 and the operation keys 43, and connected to the main CPU 10.

Then, an image reading operation in the case of using a fadeable toner in an image forming apparatus having such a structure will be described below.

First, in order to explain this embodiment, a conventional case will be described.

FIG. 2 is a view showing an example of an object printed using conventional toner.

FIG. 3 is a graph showing concentration-frequency curve data of the subject in FIG. 2 .

FIG. 4 is a graph showing density-frequency curve data for copying an object printed using conventional toner after image processing.

The dynamic range width between the lower density side and the higher density side of the density frequency curve data in FIG. 3 is expanded in the density frequency curve data in FIG. 4 (expansion of the dynamic range width). This is because the lower density side is set so that image processing is performed when a density not higher than a certain threshold is recognized as a white background surface to create a better quality even for images with certain images such as newspapers. concentration of objects (threshold 1 in Figure 4). In addition, on the higher density side, in order to increase the reproducibility and better quality of objects written by pencil, image processing is performed so that the density not lower than a certain threshold is deepened (threshold 2 in FIG. 4 ). These image manipulations are called range corrections.

Also, at an intermediate density between Threshold 1 and Threshold 2, image processing is performed to make the density slightly higher than that of the subject to improve document reproducibility.

On the other hand, FIG. 5 is a view showing an example of an object printed using fadeable toner. Here, the image density is set to be relatively low relative to an image printed using general toner to ensure fading properties. In addition, fadeable toners having different colors from general black toners are generally used in order to be easily distinguished from general printing materials.

FIG. 6 is a view showing an example of an image after fading of an image printed using a fadeable toner. As described above, after fading, the coloring properties of the toner disappear, but the components of the toner remain on the paper. Therefore, slight print marks may be visible, depending on the viewing angle.

If you print with fadeable toner on paper that has faded print marks, you get the image shown in Figure 7. As shown in FIG. 7 , the image is a case where printing using fadeable toner is performed on a background surface with slightly visible print traces.

FIG. 8 is a graph showing density-frequency curve data of the image in FIG. 7 . At this time, there are traces of printing remaining on the background surface of the paper, thus having a density of threshold 1 or higher, and the higher density side is light printing, thus providing data having a threshold of 2 or less.

Also, if general image processing is performed using the image shown in FIG. 7 with the density-frequency curve data of FIG. 8, the result will be described below.

FIG. 9 is a view showing the result of the image processing described above. As shown in Figure 9, both characters and faded background surface traces were recognized for printing, making it difficult to view the image. Also, the characters are printed lightly, which do not undergo the aforementioned range correction which does not give dark printing, and thus blend with the printed background surface, which further makes the image difficult to view.

Here, embodiments of the present invention are designed to eliminate problems that arise when copying, scanning, faxing objects obtained by printing paper with faded toner traces with fadeable toner. In other words, when using an object obtained by printing with a fadeable toner on paper with faded traces of fadeable toner, the embodiment of the present invention is designed to switch one of threshold 1 and threshold 2 different from the image processing described above. or multiple image processing to obtain ideal high-quality images.

More particularly, for an object obtained by printing paper with faded traces of fadeable toner using fadeable toner, threshold 1a and threshold 2a different from threshold 1 and threshold 2 described above are prepared for conversion.

FIG. 10 is a graph showing an example of setting the threshold 1a and the threshold 2a.

In this embodiment, a threshold change key (not shown) is shown on the liquid crystal display 42 of the operation panel 4 .

When copying an object obtained by printing paper with faded traces of fadeable toner using fadeable toner, a threshold change key (not shown) is displayed on the liquid crystal display 42 of the operation panel 4 and pressed .

The main CPU 10 sets the threshold 1a and the threshold 2a in the image processing unit 13 when a threshold change key (not shown) displayed on the liquid crystal display 42 of the operation panel 4 is detected by the touch panel 41.

The image processing unit 13 eliminates the background surface as shown in FIG. 11 by using the set threshold 1a and threshold 2a, thereby realizing printing with a darker high-quality image.

Moreover, due to the repetition of printing, erasing, printing, erasing, etc., the residual trace layer after fading gradually becomes darker. Therefore, the levels of both threshold 1 and threshold 2 need to be changed, and threshold 1b and threshold 2b are set on the higher density side than threshold 1 and threshold 2 after the second erasing. Threshold 1c and threshold 2c, threshold 1d and threshold 2d, etc. should be prestored in a nonvolatile memory (not shown) in the same manner.

For example, the main CPU 10 displays the selection key on the liquid crystal display 42 after the first erasing, the second erasing, the third erasing, and the fourth erasing.

In addition, a threshold value change key (not shown) is provided in the operation key 43 . The main CPU 10 changes the setting of the thresholds by setting the thresholds 1a and 2a once, setting the thresholds 1b and 2b a second time, setting the thresholds 1c and 2c a third time, and so on.

Due to this structure, this embodiment can provide a high-quality image on an appropriate background surface according to the number of times of erasing processing.

It should be noted that the conversion of the image processing described above is not limited to copying, but may also have thresholds optimal for scanning and facsimile, respectively.

Also, the threshold can be adjusted without any grades.

Now, modifications of the above-described embodiment will be described.

Fig. 12 shows a schematic structure of a modified color image forming apparatus according to the present invention. This color image forming apparatus includes: a main control unit 5 , a scanning unit 6 , a printing unit 7 , and an operation panel 8 .

Main control unit 5 comprises: main CPU 50, is used for carrying out the overall control of equipment; ROM 51, wherein stores control program etc.; RAM 52, is used for temporarily storing data; for image processing.

The scanning unit 6 includes: a CCD unit 62 having a full-color CCD 61; a reading control unit 63; an optical mechanism unit 64; and a platen glass 65 on which an object is placed. Here, the 4-line color CCD can be used as the full-color CCD 61.

The printing unit 7 is an image forming device for forming an image on paper based on image data.

The operation panel 8 includes: a liquid crystal display 82 with a touch panel 81; various operation keys 83; and a panel CPU 84 connected with the liquid crystal display 82 and the operation keys 83 and connected to the main CPU 10.

Then, an image reading operation using fadeable toner in the image forming apparatus having such a structure will next be described.

A variant of the invention serves to eliminate the problems that arise when copying, scanning, faxing objects obtained by printing with fadeable toner on paper with faded traces of fadeable toner. Therefore, when using an object obtained by printing with a fadeable toner on paper with faded traces of a fadeable toner, the variant of the invention is designed to switch one or Multiple image processing for ideal high-quality images.

More specifically, the color of the fadeable toner to be printed (blue in this example) is stored in advance in the main control unit 5 of the image forming apparatus. Then, when the full-color CCD 61 of the scanning unit 6 reads the object positioned on the platen glass 65, the reading control unit 63 recognizes whether or not blue is present on the object.

If the reading control unit 63 recognizes the presence of blue, the image processing unit 53 shifts to image processing for the above-mentioned fadeable toner object.

Here, the recognition condition is to avoid false recognition of a colored object instead of fadeable toner (blue) to improve recognition accuracy. However, general colored objects are rarely formed with one color. Therefore, the reading control unit 63 reduces the probability of erroneous recognition by recognizing whether the image portion on the object has only the fadeable toner (blue) previously stored in the main control unit 5 of the image forming apparatus.

Moreover, due to the repetition of printing, erasing, printing, erasing, etc., the residual trace layer after fading gradually becomes darker. By adding another recognition condition (blackening of the background surface other than the printed image portion such as characters due to the faded traces left on the background surface after fading) to the previously described condition of storing the color of the fadeable toner in advance, the Accurately identifies images with many faded traces of fadeable toner.

For example, the main CPU 50 of the image forming apparatus stores threshold 1a and threshold 1b as shown in FIG. 10 for an object obtained by printing paper with faded traces of fadeable toner using fadeable toner. When the user copies an object obtained by using fadeable toner to print paper with faded traces of fadeable toner, the main CPU 50 of the image forming apparatus passes through the switching mode (for example, an operation on the operation panel 8) The thresholds 1a and 1b are transferred to the image processing unit 53, thereby providing a deep print with a high-quality image as shown in FIG. 11 .

This modification uses a liquid crystal display 82 of the operation panel 8 as shown in FIG. 13 .

When copying an object obtained by printing paper with faded traces of the fadeable toner using fadeable toner, the fadeable toner object key 90 displayed on the liquid crystal display 82 of the operation panel 8 is pressed. Then, the main CPU 50 switches the image processing unit 53 to the threshold 1a and the threshold 1b.

Moreover, due to the repetition of printing, erasing, printing, erasing, etc., the residual trace layer after repeated fading gradually becomes black. Therefore, the level of Threshold 1 needs to be changed accordingly.

As described above, the modification of the present invention can perform automatic recognition based on the color of the fadeable toner or the like. However, the automatic fadeable toner object recognition mode key 91 allows such a function to be turned on or off.

FIG. 15 shows an example of a display of the liquid crystal display 82 to sequentially set the threshold value 1 according to the number of fading times. As shown in FIG. 15 , the threshold value 1 may be sequentially set on the higher density side such as the object key after the first erasure, the object key after the second erasure, the object key after the third erasure, and the like. The main CPU 50 changes the setting of the threshold value 1 set in the image processing unit 53 according to the key of the fade number.

If the value of Threshold 1 can be converted, a good image can be obtained on the appropriate background surface of the object according to the number of fades. The conversion of the image processing described above is not limited to copying, but may also include optimal thresholds for scanning and facsimile, respectively.

Also, the threshold can be adjusted without any grades.

Also, as shown in FIG. 15, keys 92a, 92b, 93a, and 93b may be provided to arbitrarily set the threshold values 1 and 2.

According to the above-described embodiments of the present invention, even when an object with residual faded marks (print marks) of fadeable toner on the background surface is copied, faxed, or scanned, the object has a low image density, eliminating the possibility of printing on the background. Fading marks on the surface and problems with light printing for a premium quality image.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (15)

1. An image forming device, characterized in that it comprises: a reading device for reading the image on the object; image processing means for processing the image read by the reading means; storage means for storing in advance threshold value information used in said image processing with respect to fadeable image formation of said image processing means, which is different from that used for general image formation; indicating means for indicating said threshold value information used in said image processing by said image processing means; and control means, for when the indication means indicates the threshold information, Control reads the indicated threshold information from the storage means and sets the information in the image processing means. 2. The image forming apparatus according to claim 1, wherein said storage means has a memory for storing a plurality of different threshold information in advance, and said instructing means has a key for instructing conversion of said threshold information. . 3. The image forming apparatus according to claim 1, wherein said storage means prestores threshold value information used for said image processing by said image processing means according to the number of fading times, When reading an object printed with a fadeable toner, the indicating means indicates the number of fades of the object, and When indicating the number of times of fading of the object, the control means reads the threshold value information from the storage means according to the number of times of fading and sets the information in the image processing means. 4. The image forming apparatus according to claim 1, wherein the reading device has a color CCD sensor, The storage means pre-stores threshold information for the image processing by the image processing means according to the number of fading times, When reading an object printed with a fadeable toner, the indicating means indicates the number of fades of the object, and The control means reads the threshold value information from the storage means according to the fading number and sets the information in the image processing means when the number of times of fading with respect to the object is indicated. 5. The image forming apparatus according to claim 1, wherein said reading means comprises a color CCD sensor and a determining means, and said determining means is used to read a color when said reading means having said color CCD sensor when fetching an object, determine whether the object is printed with fadeable toner, and When the determination means determines that the object is printed with fadeable toner, the control means uses the threshold information previously stored in the storage means to cause the image processing means to switch to the The image processing of the fadeable toner object. 6. An image processing method, characterized in that comprising: read the image on the object; processing said image read by said reading step; storing in advance threshold value information for use in said image processing of fadeable image formation with respect to said processing steps, which is different from that used in general image processing; indicating said threshold information for said image processing of said processing step; and When threshold information is indicated, the indicated threshold information is read from said threshold information stored in advance and said information is set in said processing step. 7. The image processing method according to claim 6, wherein the pre-stored threshold information is a plurality of different threshold information, and The indicating step indicates conversion of the threshold information. 8. The image processing method according to claim 6, further comprising: Pre-store threshold information for the image processing of the processing step according to the number of fading times; when reading an object printed with the fadeable toner, indicating the number of times the object has faded; and When the number of times of fading with respect to the object is indicated, the threshold value information is read according to the number of times of fading, and the information is set in the processing step. 9. The image processing method according to claim 6, further comprising: using a color CCD sensor in said reading step; Pre-store threshold information for the image processing of the processing step according to the number of fading times; when reading an object printed with the fadeable toner, indicating the number of times the object has faded; and When the number of times of fading of the object is indicated, the threshold information is read according to the number of times of fading, and the information is set in the processing step. 10. The image processing method according to claim 6, further comprising: using a color CCD sensor in said reading step; determining whether the object is printed with fadeable toner; and The previously stored threshold information is used to switch to the image processing for the fadeable toner object when it is determined that the object is printed with fadeable toner. 11. An image forming device, comprising: a reading unit for reading the image on the object; an image processing unit for processing the image read by the reading unit; a storage unit for pre-storing threshold value information for image processing use related to the fadeable image formation of the image processing unit which is different from general image processing use; an indication unit for indicating the threshold information for image processing by the image processing unit; and A control unit, when the threshold information is indicated by the indication unit, controls to read the indicated threshold information from the storage unit, and set the information in the image processing unit. 12. The image forming apparatus according to claim 11, wherein the storage unit has a memory for storing a plurality of different threshold information in advance, and the instructing unit has a key for instructing conversion of the threshold information . 13. The image forming apparatus according to claim 11, wherein the storage unit pre-stores threshold information used for the image processing by the image processing unit according to the number of fading times; When an object printed with the fadeable toner is read, the indication unit indicates the number of fading times of the object, and When the number of times of fading of the object is indicated, the control unit reads the threshold value information from the storage unit according to the number of times of fading and sets the information in the image processing unit. 14. The image forming apparatus according to claim 11, wherein the reading unit has a color CCD sensor, the storage unit pre-stores threshold information for the image processing by the image processing unit according to the number of fading times, When an object printed with the fadeable toner is read, the indication unit indicates the number of fading times of the object, and When the number of times of fading of the object is indicated, the control unit reads the threshold value information from the storage unit according to the number of times of fading and sets the information in the image processing unit. 15. The image forming apparatus according to claim 11, wherein the reading unit includes a color CCD sensor and a determination unit, and the determination unit is configured to read a color when the reading unit having the color CCD sensor reads When fetching an object, identifying whether the object is printed with fadeable toner; and When the determination unit determines that the object is printed with fadeable toner, the control unit switches the image processing unit to the The image processing of the fadeable toner object.

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