JP2012093545A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low cost printer capable of printing in a high printing quality even after the toner shortage without the change in a print color between before and after the toner shortage.SOLUTION: A printer 1 comprises a normal image processing part 5a for performing normal image processing on original image data, and a character/fine line image extraction processing part 5b for performing on the original image data image processing including character/fine line image extraction processing which extracts only parts composed of characters and/or fine lines in the original image. When the toner residual amount is more than a predetermined value, the printer device 1 prints an image on a recording medium according to the original image data on which the normal image processing is performed, and when the toner residual amount is less than the predetermined value, the printer prints the image on the recording medium according to the original data on which the normal image processing is performed, and further prints, overlapping the original image on the recording medium, parts composed of characters and/or fine lines of the original image extracted by the character/fine line image extraction processing part 5b.

Description

  The present invention relates to a printing apparatus such as a copying machine or a laser beam printer that employs an electrophotographic system.

  Some printing apparatuses such as a copying machine, a printer, and a facsimile employ an electrophotographic system that forms an image using toner. In a printing apparatus using an electrophotographic system, when a toner shortage occurs, a warning for prompting replacement of toner is displayed, but the user may desire printing in that state. However, if printing is performed with the toner shortage, the printed part is missing and difficult to read.

  In order to solve this problem, the printing apparatus disclosed in Patent Document 1 includes, as a color printing apparatus, a developing device that performs development using toner for each color, and a certain color developing device operates normally due to lack of toner. When it is determined that the development cannot be performed, the developing device to be used is switched, and the image to be printed is developed and printed by the developing device for another color.

JP-A 63-153559

However, the color of the toner used in the developing device at the switching destination is different from the switching source color that should be printed. For example, when the developing device to be switched is for yellow, it is difficult to recognize a yellow image, so the effect of switching is very small.
Instead of the configuration of the above-mentioned Patent Document 1, a configuration is also possible in which a backup developing device is provided for each color, and when a toner shortage occurs for a certain color, a method of switching to the backup developing device for that color is also considered. It is done. However, this method is expensive.

  The present invention has been made in view of the above circumstances, and an inexpensive printing apparatus capable of printing with high print quality even after the toner shortage does not change before and after the toner shortage occurs. Its purpose is to provide.

  In order to solve the above problems, a first technical means of the present invention is a printing apparatus that performs printing in a form different from a case where the remaining amount of toner is greater than a predetermined value when the remaining amount of toner is less than a predetermined value, The original image data is subjected to image processing including normal image processing that performs normal image processing on document image data, and character / thin line image extraction processing that extracts only characters and / or fine line portions of the document image. A character / thin line image extraction processing unit that performs printing on a recording medium based on data of a document image on which the normal image processing has been performed when the remaining amount of toner is greater than a predetermined value. Is less than a predetermined value, after printing on the recording medium based on the data of the original image on which the normal image processing has been performed, the image is superimposed on the original image on the recording medium and extracted by the character thin line image extraction processing unit The It is obtained characterized by printing a portion consisting of characters and / or fine lines of the original image.

  According to the present invention, in the case of toner shortage, after printing as usual once, only the character / thin line portion of the original image is overprinted, and a portion with a large amount of toner consumption such as a photo portion or a solid black portion. Therefore, an easy-to-read printed matter in which a portion where data loss such as fine lines / characters easily occurs is reinforced can be output without excessively deficient toner. In addition, since a developing device or the like is not provided for backup when toner becomes insufficient, the cost is low. Further, a printed matter with the same printing color can be obtained before and after the toner becomes insufficient.

1 is a functional block diagram illustrating an example of an image forming apparatus of the present invention. It is a figure explaining the specific example of the image process in the normal image process part of FIG. 1, and a character / thin line image process part. 6 is a flowchart for explaining an example of processing performed when a document is copied by the multifunction peripheral of FIG. 1.

A multifunction machine as an example of a printing apparatus according to the present invention will be described with reference to the functional block diagram of FIG.
1 includes a control unit 2, a scanner unit 3, a communication processing unit 4, an image processing unit 5, a printing unit 6, a RAM 7, a ROM 8, and a recording medium transport mechanism 9.

The control unit 2 is composed of a CPU (Central Processing Unit) or the like, and reads and executes a program from a ROM (Read Only Memory) 8 while using a RAM (Random Access Memory) 7 as a work area. Control the whole. Instead of the RAM 7 and the ROM 8, other storage means such as an HDD (Hard Disk Drive) can be used.
The scanner unit 3 reads a document placed on the document table of the multifunction machine 1, and inputs and stores the read document image data in the RAM 7.
The communication processing unit 4 receives document image data from an external terminal via a communication network, and inputs and stores the data in the RAM 7.
The image processing unit 5 performs image processing on the original image data read by the scanning unit 3 or the original image data received by the communication processing unit 4 and stored in the RAM 7, and is suitable for printing by the printing unit 6. Print data. The normal image processing unit 5a and the character / thin line image extraction processing unit 5b included in the image processing unit 5 will be described later.

The printing unit 6 performs printing on a recording medium such as paper based on the print data input from the image processing unit 5. The printing unit 6 is provided on the photosensitive drum, a charging device that charges the drum, and the photosensitive drum. A laser scanning unit for forming an electrostatic latent image, a developing unit for developing the electrostatic latent image with toner to form a toner image, a transfer device for transferring the toner image onto a recording medium, and the transferred toner image on a sheet It consists of a fixing device etc. for fixing on top.
The developing device of the printing unit 6 includes a toner cartridge that contains toner, a developer container that contains a developer that is a mixture of toner and carrier replenished from the toner cartridge, and toner that detects the toner concentration in the developer container. The multifunction device 1 can determine the remaining amount of toner based on the output from the toner concentration sensor 6a.
The recording medium transport mechanism 9 is a mechanism for transporting the recording medium in the recording medium transport path from the tray in which the recording medium is stored to the recording medium discharge port.

  The multifunction device 1 functions as a copier or a printer by including the above-described units.

Next, a characteristic configuration of the multifunction machine 1 will be described.
The multifunction device 1 includes a normal image processing unit 5a and a character / thin line image extraction processing unit 5b in the image processing unit 5.
The normal image processing unit 5a performs conventional, that is, normal image processing on the document image data stored in the RAM 7, and generates print data of the document image.
The character / thin line image extraction processing unit 5b performs a process including character / thin line image extraction processing for extracting only a portion consisting of characters and / or fine lines (hereinafter referred to as a character / thin line portion) in the document image. Then, print data of the character / thin line portion of the document image is generated.

In the normal operation in which the remaining amount of toner is greater than the predetermined value, the multifunction device 1 prints the document image on the recording medium by the printing unit 6 based on the document image print data output from the normal image processing unit 5a. Then, the recording medium is discharged out of the apparatus.
On the other hand, if the remaining amount of toner is less than the predetermined value, the multifunction device 1 once prints on the recording medium as in the normal operation, but transports it back to the printing start position again without discharging the recording medium to the outside of the apparatus. . Then, the character / thin line portion of the document image is printed based on the print data output from the character / thin line image extraction processing unit 5b so as to overlap the document image on the recording medium, and then the recording medium is connected to the apparatus. Drain outside.

  Further, the recording medium transport mechanism 9 of the multi-function device 1 has a transport mechanism including a transport roller, a fixing roller and a pressure roller of a fixing device, a photosensitive drum, and the like so that printing can be performed as described above. Thus, the printed recording medium can be conveyed in the direction opposite to that during printing and returned to the printing start position.

The configuration described above has the following effects.
When the toner is insufficient, a thin line / character portion is lost, which makes it difficult to read and often reduces the gradation of a photographic portion. However, when the user desires printing in a toner-deficient state, the image quality of the photograph portion may not be improved, but it is desirable that the thin line / character portion is not lost as much as possible. With respect to this point, as described above, the multifunction device 1 once prints normally, and then superimposes only the character / thin line portion of the original image, and consumes a large amount of toner such as a photo portion or a solid black portion. Since the portion is not printed, it is possible to output an easy-to-read product in which a portion where data loss such as a fine line / character is likely to occur is reinforced without excessively lacking insufficient toner.

As described above, the present invention is not a technique for completely forming the image quality in the same state as before the toner shortage when the toner is insufficient, but the output printing efficiency is poor even if the toner is insufficient. This is a technique for improving a character / thin line portion so that a recording medium on which an image is formed functions as an information transmission means. In other words, when the amount of toner decreases, the fine line / character portion may impair the value of the information transmission means as a printed matter when chipping occurs, while the photo portion has a relatively poor gradation. However, it does not impair the quality of information transmission means. Therefore, in the present invention, the thin line / character portion is reinforced without reinforcing the portion with a large amount of toner consumption such as a photo portion or solid black so that the consumption amount of the toner which has been reduced is not increased any more. As a result, even when the amount of toner is low, the minimum required print quality is maintained until the toner cartridge is replaced.
In the present invention, a separate apparatus is not provided for printing in a state where the toner is low, and the cost is low. In addition, there is no color change even in the case where the toner is low, and the original image The situation can be reproduced more accurately.

A specific example of image processing in the normal image processing unit 5a and the character / thin line image processing unit 5b in FIG. 1 will be described with reference to FIG. 2A and 2B are examples of filter coefficients used for image processing in the normal image processing unit 5a, and FIGS. 2C and 2D are examples of filter coefficients used in the character / thin line image processing unit 5b. It is an example of image processing.
The normal image processing performed on the image of the original image by the normal image processing unit 5a is general, for example, (a) pre-processing (shading, input gamma processing, etc.), (b) region separation processing , (C) filter processing (for each separated area), (d) post-processing (resolution conversion, black generation, output density processing, etc.), and (e) output data generation processing (CMYK conversion, etc.).

  On the other hand, in the image processing performed by the character / thin line image processing unit 5b, in addition to the above (a), (b), (d), and (e), (c ′) the character / thin line portion of the document image is extracted. Perform filtering. The order of processing is (a) → (b) → (c ′) → (d) → (e). That is, only the filter processing is different between the normal image processing unit 5a and the character / thin line image processing unit 5b. Specifically, the filtering process for extracting the character / thin line portion can be realized by performing the following settings, for example.

  As shown in FIGS. 2A and 2B, filter processing in normal image processing is suitable for printing in both the character / thin line area and the other area (here, the photograph / background area). Set an optimal filter coefficient that is not zero so that the image quality is improved. On the other hand, in the filter processing for extracting characters / thin lines, as shown in FIGS. 2C and 2D, the same filter coefficients as those in normal image processing are set as the filter coefficients for the characters / thin lines. The filter coefficient of the background area is set to zero. By setting the filter coefficient in this way, the character / thin line portion can be extracted.

Next, an example of processing that is performed when a document is copied by the multifunction device 1 of FIG. 1 will be described with reference to FIG.
In the multifunction device 1, when a copy instruction is input, the document placed on the document table is read by the scanner unit 3, and the RGB data of the document for one page is stored in the RAM 7 (step S1). Then, the stored image data is read out, the normal image processing unit 5a performs normal image processing on the image data (step S2), and the obtained CMYK print data is temporarily stored in the RAM 7 (step S2). S3) The data can be transferred to the printing unit 6 at any time.

Next, based on the output from the toner density sensor 6a, it is determined whether or not the remaining amount of toner is less than a predetermined value (step S4). The predetermined value information is stored in the ROM 8, for example.
When the remaining amount of toner is larger than the predetermined value (step S4, NO), the printing image data stored in the RAM 7 is read, the original image is printed on the paper by the printing unit 6 (step S5), and the paper is discharged (step). S6).
On the other hand, if the remaining amount of toner is less than the predetermined value (step S4, YES), the print data stored in the RAM 7 is read and the original image is printed on the paper by the printing unit 6 (step S7). The discharge roller, the fixing roller, the photosensitive drum, and the like constituting the paper 9 are reversely rotated to draw the paper on which the original image is printed to the printing start position (step S8), and the printing unit 6 prepares for reprinting. Keep it like that.

  Further, the RGB data of one page of the document stored in the RAM 7 is read out, and image processing including character / thin line extraction processing is performed on the data by the character / thin line image processing unit 5b (step S9). The CMYK print data of the character / thin line portion is stored in the RAM 7 (step S10). Then, the print data is read out and printed by the printing unit 6 so that only the character / thin line portion of the original image is superimposed on the original image on the paper (step S11), and the process proceeds to step S6. Make paper.

  In place of the present invention, a method of increasing the thickness of the character / thin line by image processing to improve only the character / thin line portion of the original image can be considered, but there is a possibility that the character may be crushed. High and not the best.

DESCRIPTION OF SYMBOLS 1 ... Printing apparatus, 2 ... Control part, 3 ... Scanner part, 4 ... Communication processing part, 5 ... Image processing part, 5a ... Normal image processing part, 5b ... Character / thin line image extraction processing part, 6 ... Printing part, 7 ... RAM, 8 ... ROM, 9 ... paper transport mechanism.

Claims (1)

A printing apparatus that prints in a form different from a case where the remaining amount of toner is greater than a predetermined value when the remaining amount of toner is less than a predetermined value,
A normal image processing unit that performs normal image processing on document image data;
A character / thin line image extraction processing unit that performs image processing including character / thin line image extraction processing for extracting only a part consisting of characters and / or fine lines in the original image,
When the remaining amount of toner is greater than a predetermined value, printing on a recording medium based on the data of the original image on which the normal image processing has been performed,
When the remaining amount of toner is less than a predetermined value, the character thin line image is extracted after being printed on a recording medium based on the data of the original image that has been subjected to the normal image processing and then superimposed on the original image on the recording medium. A printing apparatus that prints a portion of characters and / or fine lines of a document image extracted by a processing unit.

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