KR20000056599A - Image printing apparatus - Google Patents

Abstract

An image printing apparatus is disclosed. The image printing apparatus includes a plurality of halftone tables in which patterns of elements are different from each other in a predetermined number of pixel comparison elements set as a comparison table for determining toner writing / missing for each pixel of the original image. And selecting a halftone table corresponding to the input toner consumption mode selection signal for the received original image represented by grayscale gradation value for each pixel, and comparing each element value of the selected halftone table by the comparison unit by the comparison unit. The image corresponding to the printed image information output from the controller for toner writing / missing for each pixel as a comparison result of each pixel as a result of comparison of each pixel Toner consumption mode selection means for outputting an engine and toner consumption mode selection signal to the controller for printing the The rain. According to such an image printing apparatus, in the toner consumption saving mode, the printing process is performed by a method of dropping some pixel colors without dropping the gradation reproduction power, thereby reducing the toner consumption without significantly reducing the print quality of the original color image. There is an advantage to reduce.

Description

Image printing apparatus

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image printing apparatus, and more particularly, to an image printing apparatus in which toner consumption to a recording medium can be adjusted through image data conversion processing.

An image printing apparatus such as a copier, a printer, or a facsimile prints an image corresponding to the received original image data on a recording medium such as paper.

In general, original image information acquired by a scanner or a video camera of a subject is expressed by subdividing it into 256 gray levels for one pixel. In addition, an original image generated by a computer text editor is displayed with grayscale information of 256 gradations. By the way, most printing apparatuses such as inkjet printers, laser printers, copiers, and facsimiles are developer (hereinafter referred to as toner) for each dot corresponding to one pixel area even though the received image information is expressed in several steps for the pixel. Image processing can be performed by only turning on / off for writing, and the ability to reproduce pixel gradations of the original image expressed in plural levels of grayscale for one pixel area is limited.

On the other hand, as a way to reduce the consumption of the developer (hereinafter referred to as toner) when the original image is reproduced on the recording medium by using such an image printing apparatus, conventionally the data of some pixels of the data of the original image There is a method in which it is omitted at regular intervals and transmitted to the image printing apparatus. However, such a method of simply missing pixel data at regular intervals has a problem in that the image quality cannot be reproduced in close proximity and thus the image quality is greatly reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide an image printing apparatus capable of reducing the consumption of toner by selection without significantly reducing the gradation reproduction power of an original image.

1 is a block diagram showing an image printing apparatus according to the present invention,

FIG. 2 is a diagram illustrating a pixel gray data processing process for explaining the principle of halftoning processing by the controller of FIG. 1.

FIG. 3 is a flowchart illustrating a halftone table selection process when a toner saving halftone table and a non-toner saving halftone table are provided in the controller of FIG. 1 and a halftoning process by the selected halftone table. ,

4 is a block diagram illustrating an embodiment of some blocks of the controller of FIG. 1;

Fig. 5A is a diagram showing an example of the print processing result by the halftone table for non-toner saving mode;

Fig. 5B is a diagram showing an example of the print processing result by the halftone table for the toner saving mode in comparison with Fig. 6A.

<Explanation of symbols for main parts of drawing>

10: controller 11: image data conversion unit

12: halftoning processor 13: first memory

14: second memory 15: inverter

20: Input device 21: Toner consumption mode selection key

30: engine 31: photosensitive belt

32: reset device 33: optical scanning device

34: developer 35: drying device

36: transfer device 37: paper

40: display device

In order to achieve the above object, the image printing apparatus according to the present invention has different setting of element values with respect to a predetermined number of pixel comparison elements set as a comparison table for determining toner writing / missing for each pixel of an original image. A plurality of halftone tables in a pattern are provided, the halftone tables corresponding to the input toner consumption mode selection signal for the received original image expressed in grayscale gradation values for each pixel are selected, and the selected halftone table is selected. A controller for comparing each element value by a comparison unit with the pixel gradation value of the original image and outputting the comparison result as print image information; An engine which prints an image on a recording medium corresponding to the print image information output from the controller for toner writing / missing for each pixel as a result of comparison of each pixel of the original image; And a toner consumption mode selection step of outputting the toner consumption mode selection signal to the controller.

Preferably, the controller comprises: a first memory in which a non-toner saving printing halftone table used in the non-toner saving mode is recorded; A second memory in which a toner saving printing halftone table used in the toner saving mode is recorded; Selecting any one of the first memory and the second memory corresponding to the toner consumption mode selection signal, and comparing the gray level value of each pixel of the original image with a corresponding comparison element value of the selected halftone table; And a halftoning processor for outputting the comparison result as print image information. Further, the toner saving printing halftone table is preferably configured to contain more elements having a value corresponding to the grayscale maximum value than the nontoner saving printing halftone table.

Hereinafter, an image printing apparatus according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing a color image printing apparatus according to the present invention.

Referring to the drawings, the color image printing apparatus includes a controller 10, an input device 20, an engine 30, and a display device 40.

The input device 20, which is a toner consumption mode selection means, is provided with a toner consumption mode selection key 21 for selecting a toner consumption mode set in a plurality of steps such that the toner consumption amount is different for the same original image received. When the toner consumption mode set to be selected is three or more modes, the toner consumption mode selection key 21 is provided as an arrow key for adjusting the mode up and down, and the result of the selected mode is controlled by a controller controlled by the controller. It is desirable to be able to confirm.

On the other hand, when the set toner consumption mode is set to select one of two modes, namely, non-toner saving mode and toner saving mode, the toner saving mode is selected when the toner consumption mode selecting key 21 remains on. It can be configured to output the selection signal and output the non-toner saving mode selection signal when the toner consumption mode selection key 21 is kept off.

The controller 10 controls the overall printing apparatus, processes the instructions received from the input apparatus 10, and receives them from an external device such as a computer (not shown) or a scanner (not shown) through a communication interface. The print image data obtained through the half-toning process corresponding to the selected toner consumption mode is output to the engine 30.

The engine 30 is different in its configuration depending on the printing method, for example, an inkjet method, an electrophotographic method, a thermal transfer method, or the like.

The illustrated engine is a wet electrophotographic method, and includes a photosensitive belt 31, a reset device 32, a plurality of optical scanning devices 33, a plurality of developing devices 34, a drying device 35, and a transfer device 36. Equipped.

The reset device 32 includes an exposure device 32a for erasing the electrostatic latent image so that a new electrostatic latent image can be written on the photosensitive belt 31, and a charger 32b for charging the photosensitive belt 31 to a predetermined potential. Doing.

Each of the four optical scanning devices 33 scans the photosensitive belt 31 with light corresponding to yellow (y), magenta (m), cyan (c) concentration data, and black (k) concentration data.

Each of the four developing units 34 supplies a photosensitive belt 31 with a developer of yellow (y), magenta (m), cyan (c), and black (k) colors to the photosensitive belt 31, and then to the photosensitive belt 33 by the optical scanning device 33. The electrostatic latent image formed at 31 is developed.

The drying apparatus 35 is for adsorbing and evaporating the liquid carrier element which is not related to image formation when a liquid ink in which a toner and a liquid carrier element are mixed is used as a developer.

The transfer device 36 transfers the color image formed by the color-specific optical scanning device 33 and the developing device 34 to the photosensitive belt 31 onto the supplied paper 37.

In the case where the engine 30 having such a structure is to print only one pixel with toner writing on / off, the half-toning processing principle of the controller 10 for enhancing the gradation reproduction power of the original image will first be described with reference to FIG. do. In the drawing, a _ij represents a pixel gray value of the received input image, b _ij represents a comparative element value of the selected halftone table, and c _ij represents (i, j = 1 to 4) the pixel gray value and the half of the input image. Shows the result of comparison with the element values in the tone table.

First, the halftone table is set in a matrix form having a predetermined number of elements so that a plurality of pixels are compared units. Then, the element value of this halftone matrix and the pixel tone value of the original image are compared for each corresponding position, and the result of the comparison is generated as print image data.

For example, when the selected halftone table is set to the 4x4 halftone matrix as shown in the drawing, for each corresponding position, the element value in the halftone matrix is the same number of input image data, that is, 4x4 pixels as a comparison unit. One-to-one comparison is made with on-data that is printed only when the grayscale value of the input image data is greater than (or may be equal to or larger than) the element value of the corresponding halftone matrix. At this time, the image data of the entire image is repeatedly compared with the same number of image data as the number of elements of the halftone matrix, and the result is output to the engine 30. In order to increase the gradation reproduction power of the continuous gradation image data input and expressed in 256 steps, the number of rows and columns of the halftone matrix that becomes the gradation reproduction block unit should be increased. However, if the number of elements of the halftone matrix is increased, the resolution of the reproduced image is reduced, so that the number of elements is appropriately selected in consideration of the resolution.

The case where the toner consumption mode is set to the non-toner saving mode and the toner saving mode in two steps for the data processing of the controller 10 based on the halftoning processing principle will be described.

First, when original image data represented by several levels of grayscale information is received for a pixel, it is determined whether the toner saving printing mode is selected (step 110).

If it is determined in the determination step 110 that the toner saving printing mode is set, a halftone table for toner saving printing is selected for data conversion comparison (step 120).

In contrast, if it is determined that the non-toner saving printing mode is set in the determination step 110, the non-toner saving printing halftone table is selected for data conversion comparison (step 130).

The image data for printing is generated as a halftone table selected through any one of steps 120 and 130 through a halftoning process as described above with reference to FIG. 2.

This data conversion process may be configured to be performed by execution of an operating program installed in the controller, or may be configured in hardware.

4 shows an example of a configuration of some elements of the image data conversion unit 11 in the controller 10 which performs the image data conversion process.

Referring to FIG. 4, the data converter 11 performing image data conversion includes a halftoning processor 12, a first memory 13, and a second memory 14.

As used in the non-toner saving mode, the first memory 13 records, as a table, element values on a matrix for comparing pixel grayscale values of a predetermined number of original images as a comparison unit. The element values are determined in the halftone table of the first memory 13 so as to reproduce the gradation of the original image to the maximum possible. The element values in the halftone table of the first memory 13 are set such that the element values differ by a value approximately equal to the quotient of dividing the grayscale maximum value by the number of elements within the grayscale range. The arrangement of the set elements in the matrix can be variously selected.

In the second memory 14, which is used in the toner saving mode, the element value corresponding to the highest grayscale value is set to be larger than the number of elements of the non-toner-saving printing halftone table so as to reduce the toner consumption. For example, when the gray scale value of the received original image is expressed in 256 steps from 0 to 255, the number of elements having a value of 255 in the toner saving printing halftone table recorded in the second memory 14 is the circle of the halftone matrix. It is set to occupy a certain ratio for a few. Since the element value 255 corresponds to the toner missing, the number of elements having an element value of 255 in the halftone matrix directly connected to the toner missing is appropriately set.

The first memory 13 and the second memory 14 may provide information recorded by only one of the first memory 13 and the second memory 14 according to the selected toner consumption mode selection signal through the operation of the toner consumption mode selection key 21 of the input device 10. The second memory 14 allows the toner consumption mode selection signal to be input to the enable terminal EN to enable reading, while the first memory 13 allows the toner consumption mode selection signal to be inverted by the inverter 15. The signal inverted through the V-C is input to the enable terminal EN.

Alternatively, the toner consumption mode selection signal may be input to the halftoning processing unit 12, and the halftoning processing unit 12 is configured to select and use either the first memory 13 or the second memory 13. do.

The halftoning processor 12 compares the received original image pixel gradation values with the matrix element values read from the memory in the active state in response to the toner consumption mode selection signal and outputs the result to the engine 30. .

In this way, the image corresponding to the image data output as on / off information on the toner writing / missing to the pixel via the halftoning processing section 12 is printed by the engine 30.

5A and 5B show examples of print processing results when the non-toner saving mode and the toner saving mode are selected for the same original image.

The toner saving halftone table applied to Fig. 5B is set such that eight of the elements in the halftone table having 16 elements have a value of 255, and as a result, there is no non-toner saving element with no element having an element value of 255. Compared with the print processing result of FIG. 6A by the halftone table, the image quality is relatively blurred, but the gray scale reproduction is similarly displayed.

As described so far, according to the image printing apparatus according to the present invention, in the toner consumption saving mode, the print quality of the original color image is reduced because the printing process is performed by a method of dropping some pixel colors without reducing the gray scale reproducibility. There is an advantage that the consumption of toner can be reduced without dropping significantly.

Claims (4)

A plurality of halftone tables are provided in a pattern in which the element values are different from each other for a predetermined number of pixel comparison elements set as a comparison table for determining toner writing / missing for each pixel of the original image. Selecting a halftone table corresponding to the input toner consumption mode selection signal for the received original image expressed in grayscale gradation values, the pixel gradation value of the original image by the unit of comparison of each element value of the selected halftone table And a controller for outputting the result of the comparison as print image information in comparison with; An engine which prints an image on a recording medium corresponding to the print image information output from the controller for toner writing / missing for each pixel as a result of comparison of each pixel of the original image; And And toner consumption mode selection means for outputting the toner consumption mode selection signal to the controller. The method of claim 1, The controller comprises: a first memory in which a non-toner saving printing halftone table used in the non-toner saving mode is recorded; A second memory in which a toner saving printing halftone table used in the toner saving mode is recorded; Selecting any one of the first memory and the second memory corresponding to the toner consumption mode selection signal, and comparing the gray level value of each pixel of the original image with a corresponding comparison element value of the selected halftone table; And a half-toning processing unit for outputting the comparison result as print image information. The method of claim 2, And the element values are set such that the toner saving printing halftone table contains more elements having a value corresponding to the grayscale maximum value than the nontoner saving printing halftone table. The method of claim 1, And the toner consumption mode selection means is provided outside the main body so as to be operated by the user.