JPH11254753A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress consumption of printing material at the time of printing without sacrifice of image quality by modifying the pattern for decimating a pixel data depending on the direction of a sheet when printing is performed using a save print function. SOLUTION: If a mask pattern is fixed although the same image data is thinned out by using the same mask pattern, the assigning direction of the mask pattern is varied by 90 deg.. Consequently, a mask pattern must be selected such that no change appears even if the mask pattern is turned by 90 deg.. Two types of mask patterns A, B are prepared such that they match with each other upon turning by 90 deg. and one mask pattern A or B is chosen dependently on the carrying direction so that the direction of mask pattern is matched with that of a sheet in any carrying direction thus eliminating difference of image quality.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus such as a laser printer and a digital copying machine, and more particularly to a printing apparatus having a save printing function for reducing the amount of toner and ink used.

[0002]

2. Description of the Related Art In printing devices such as laser printers and digital copiers, when performing printing that does not require high quality image quality, such as test printing, printing is performed on paper by thinning out pixel data and outputting. Some printers have a save printing function that suppresses the consumption of printing materials such as toner and ink.

[0003]

However, in the above-described conventional printing apparatus, only one thinning-out pattern of pixel data for printing by the save print function is prepared, so that the same print data is output. However, there is a problem that the printing result looks different depending on the direction of the paper to be printed, that is, whether the longitudinal direction of the paper is parallel or orthogonal to the paper transport direction. For this reason, a thinning pattern that does not show a difference even when rotated by 90 ° is used so that the thinning pattern does not change depending on the paper direction. As a result, save printing is performed regardless of the paper direction. There is a problem that the image quality at the time deteriorates on average. Accordingly, an object of the present invention is to provide a printing apparatus having a save printing function capable of performing printing while suppressing the consumption of printing materials such as toner and ink without deteriorating image quality as much as possible. is there.

[0004]

In order to solve the above-mentioned problems, the present invention provides a method of inputting bitmap image data,
By thinning out and outputting a part of the pixel data,
In a printing apparatus having a save printing function that reduces the amount of printing material printed on paper, when performing printing with the save printing function, the thinning pattern that thins out part of the pixel data is changed according to the direction of the paper. I did it. As a result, save printing can be performed using a thinning pattern that can minimize the deterioration of image quality according to the direction of the paper, so that consumption of printing materials such as toner and ink can be performed without deteriorating image quality as much as possible. Printing can be performed while the amount is suppressed, and the problem that the printing result looks different depending on the direction of the paper is also eliminated.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a main block diagram of a printing apparatus showing an example of an embodiment of the present invention, and shows a configuration of an image processing unit of the printing apparatus. In FIG. 1, input image data 101 input to an image processing unit 100 is temporarily
The image data is stored in the input image buffer 102 and input to the image correction unit 103 as bitmap image data. The image correction unit 103 performs a pixel determination of the input image data, and when the pixel data is determined to be a correction target pixel, performs a correction process such as edge smoothing to output the correction data 104 and simultaneously outputs the correction data selection signal 105. I do. The correction data 104 and the correction data selection signal 105 are input to the output image selection unit 106. Also, the input image buffer 1
From 02, image data that does not pass through the image correction unit 103 is also output. The uncorrected image data 111 is input to the output image selection unit 106 and has a data path. The toner save control unit 108 controls whether or not to output image data with reference to the thinning pattern (here, referred to as a mask pattern) data that matches the direction of the sheet to be printed, based on the sheet direction detection signal 109. Is output for each pixel. The mask control signal 110 is input to the output image selection unit 106. Output image selection unit 1
Reference numeral 06 denotes pixel data to select the correction data 104 or the uncorrected image data 111 for each pixel according to the correction data selection signal 105, and to output the selected data further based on the mask control signal 110. Then, only the pixel data to be output is selected and output as the output image data 107. That is, the output image selecting unit 106 performs the pixel data thinning process.

FIG. 2 is a block diagram showing the configuration of the toner save control unit 108. The toner save control unit 108
A mask pattern storage unit 202 capable of storing a plurality of mask pattern data 201 and mask pattern data suitable for the direction of the paper at the time of printing are read out from the mask pattern storage unit 202 based on the paper direction detection signal 109, and the mask pattern data is referred to. And a mask data selection unit 203 that outputs a mask control signal 204 for controlling whether or not to output image data for each pixel. The vertical synchronization signal 205, the horizontal synchronization signal 206, and the pixel clock signal 207 are also input to the mask data selection unit 203. In the toner save control unit 108, the mask data selection unit 203 reads out the mask pattern data corresponding to the direction of the paper at the time of printing from the mask pattern storage unit 202 based on the paper direction detection signal 109, and refers to the mask pattern data. By outputting the mask control signal 204 on a pixel-by-pixel basis, the output image selection unit 106 performs a pixel data thinning process that matches the direction of the paper at the time of printing. FIG. 3 shows a process example of the thinning process according to the mask pattern data. FIG. 4 shows an example of a print result when save printing is performed by changing the paper conveyance direction (printing direction) during printing using mask pattern data that becomes a different pattern when rotated by 90 °.

In the case of FIG. 4, since the same image data is thinned out using the same mask pattern, the mask pattern is fixed. Therefore, the mask pattern allocation direction depends on the transport direction of the printing paper. 90 ° different. For this reason, it is necessary to select a mask pattern that does not make a difference even if the conventional mask pattern is rotated by 90 °. On the other hand, in the present invention, as shown in FIG. 5, data of two types of different mask patterns A and B that match each other when rotated by 90 ° are prepared, and the data is prepared according to the transport direction of the paper to be printed. By selecting one of the mask patterns A or B that matches the transport direction and matching the direction of the mask pattern with respect to the paper in either transport direction so as to perform processing that does not cause a difference in the output result. Can be. These processes correspond to a plurality of mask patterns A,
This can be realized by improving hardware such as adding a memory for storing B and improving software such as selecting a mask pattern. If the software is improved so that the mask patterns A and B are rewritten, an existing memory can be used. Further, in addition to the above processing, the boundary between the white data and the black data, that is, the outline of the image is extracted. If the pixel of interest is a part of the outline of the image, the black data of the pixel of interest is changed to the normal 1 bit. It is desirable to perform a process of replacing pixel data so as to print at a density lower than that of the dots, and to perform a process of thinning out pixels with a normal mask pattern for black dots other than the outline.
In this way, even if save printing is performed, the outline of the image is not thinned out, so that an output image with high visibility can be obtained (see FIG. 6D). That is, as shown in FIG. 6B, when the thinning process is performed only on the solid black portion while leaving the outline of the image, for example, when a sentence including many characters of 9 to 10 points is output, the outline of the character is changed. There was a drawback that the output was large and the save effect was not improved. In addition, when all the lines including the outline are subjected to the thinning processing as shown in FIG. 6C, the outline of the character or image becomes a rough line, and the visibility of the image is reduced.

On the other hand, as shown in FIG. 6D, the visibility of the output image can be increased by outputting the image without thinning out the outline, and by combining this with the process of lowering the outline density, the image shown in FIG. The effect of suppressing the consumption of the printing material such as toner or ink is greater than in the case where the contour is output without thinning out as shown in FIG. Further, in a printing apparatus capable of printing multi-valued gradations per pixel, a table stores a gradation of output data and a correction value for image correction for linearly correcting the gradation of an actual output result. , The density of the pixels can be suppressed by changing the table of the correction values. Also, in the original image data, by adjusting the correction table so that the low-density image data is not erased by this save process so that the low-density data is not excessively saved, the pixel data is not lost. In addition, it is possible to suppress consumption of printing materials such as toner and ink.

[0009]

As described above, according to the present invention, it is possible to perform save printing using a thinning pattern that can minimize the deterioration of image quality according to the direction of paper. It is possible to perform printing while suppressing the consumption of the printing material such as toner and ink without deteriorating, and it is possible to solve the problem that the printing result looks different depending on the paper direction. Further, since the degree of freedom in selecting a thinning pattern is increased, the consumption of printing material can be more effectively suppressed, and the possibility of developing a thinning pattern that can further improve image quality increases.

[Brief description of the drawings]

FIG. 1 is a main block diagram of a printing apparatus showing an example of an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a toner save control unit illustrated in FIG. 1;

FIG. 3 is an explanatory diagram showing an example of a process of a thinning process according to mask pattern data.

FIG. 4 is an explanatory diagram showing processing steps and an example of a printing result when save printing is performed by changing a printing direction in a conventional printing apparatus.

FIG. 5 is an explanatory diagram showing processing steps and an example of a printing result when save printing is performed by changing a printing direction in the printing apparatus according to the present invention.

6A is a diagram illustrating an example of a print result obtained by performing save printing on an input image by various methods with respect to the input image, and FIGS.

[Explanation of symbols]

100 image processing unit, 101 input image data, 102
Input image buffer, 103 image correction unit, 104 correction data, 105 correction data selection signal, 106 output image selection unit, 108 toner save control unit, 109 paper direction detection signal, 110 mask control signal, 111 uncorrected image data, 201 Mask pattern data, 2
02 mask pattern storage unit, 203 mask data selection unit, 204 mask control signal.

Claims (1)

[Claims] 1. A method for inputting bitmap image data,
By printing out the pixel data, in a printing apparatus having a save printing function to reduce the amount of printing material used for printing on paper, the printing is performed by the save printing function. A printing apparatus, wherein a thinning pattern for thinning pixel data is changed.