JPH0481948B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multi-gradation printing device, and particularly to a multi-gradation printing device suitable for printing pixels constituting an image with three or more gradation levels. The present invention relates to a gradation printing device.

[Conventional technology]

Conventionally, in this type of printing apparatus, many methods of printing based on the halftone method, dither matrix method, etc. have been adopted. These methods usually perform printing based on binary expression (two gradations) of white dots or black dots. For this reason, for example, there is a problem in that the fidelity of shading is lowered for things that require detailed shading, such as photographs.

Therefore, when high fidelity is required, multi-gradation expression is performed in which the gradation of each pixel is divided into as many gradations as possible.

[Problem that the invention seeks to solve]

However, when performing multi-gradation expression as described above, increasing the number of gradations increases the amount of gradation information per pixel that must be stored. Therefore, the amount of information on one entire screen becomes enormous, which inevitably increases storage capacity and processing time.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a multi-gradation printing device that can significantly reduce the amount of print information to be handled when printing a grayscale image using multi-gradation expression.

[Means for solving problems]

The present invention performs a printing operation using print information consisting of gradation information indicating the gradation of each pixel and gradation difference information indicating whether the gradation of each pixel matches the gradation of the immediately preceding pixel. The printer is configured to include a print information editing section that edits and outputs the edited information to the print section.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

The embodiment shown in FIG. 1 includes a printing control section 2, a printing information editing section 4, and a printing section 6. The print control section 2 includes a CPU (central processing unit) and the like. The print control unit 2 receives print information expressed in multiple gradations (here, 16 gradations) for each screen from a computer (both not shown) as a host device via an interface circuit at a predetermined timing. At the same time, it is output to the print information editing section 4 in predetermined amounts. Along with this,
The print control section 2 is configured to control the print information editing section 4 and the printing section 6 based on a predetermined program installed in advance.

The print information is formed from gradation difference information and gradation information (see FIG. 2). Among these, the gradation information indicates the degree of shading of each pixel, and is shown in Figure 3a.
As shown in the figure, each pixel is expressed using 4 bits. Therefore, when the pixel is "white", the gradation information is expressed as "0000", and when the pixel is "black", it is expressed as "1111". Here, in the gradation information of each pixel,
When the same gradation continues, the gradation information of the subsequent pixel is not output. However, the information that the gradation information is continuous is transmitted by gradation difference information, which will be described later.

The gradation difference information indicates a gradation change between each pixel in a certain direction. This gradation difference information is
In this embodiment, when a certain pixel has the same gradation as the pixel on the left in the printing state, it is expressed as "0", and when it has a different gradation, it is expressed as "1". In other words, the gradation difference information is a difference encoding table consisting of 1-bit binary information for each pixel, as shown in FIG. 3b. Here, the gradation difference information corresponding to the first pixel of each dot line (for example, the leftmost pixel on the print screen in FIG. 4(a)) is always set to "1".

The print information editing unit 4 prints print information a (gradation difference information and gradation information) for each predetermined amount (for example, one rectangular area or one dot line) output from the print control unit 2.
It has a function to edit the data into a format that can be printed.
Specifically, the print information editing section 4 includes a gradation difference information storage memory 8, a gradation information storage memory 10, a shift register 12, and an output register 14, and is configured as shown in the figure. Among them, the gradation difference information storage memory 8 and the gradation information storage memory 10
temporarily stores the gradation difference information and gradation information output from the print control section 2. The shift register 12 reads and stores a predetermined amount of gradation difference information stored in the gradation difference information storage memory 8, and also reads out one bit of gradation difference information in response to a print data request signal b for each pixel from the printing unit 6. Performs shifted output. The output c of the shift register 12 controls the energization of the gradation information storage memory 10 and the output register 14. Specifically, when the output c of the shift register 12 is "1", it becomes a read request signal to the gradation information storage memory 10, sets the corresponding gradation information in the output register 14, and stores this gradation information. On the other hand, when the output c of the shift register 12 is "0", the output register 1 is output to the printing section 6.
The contents of 4 are output to the printing section 6 as they are.

The printing section 6 includes a print head, a carriage mechanism, etc. (not shown), and a drive circuit for these.

Next, the overall operation of this embodiment will be explained.

The host device outputs print information for each screen to the print control unit 2 of the multi-tone printing device at a predetermined timing. The print control section 2 outputs a predetermined amount a of the input print information to the print information editing section 4 and controls the entire apparatus. In the print information editing section 4, the input gradation difference information is stored in the gradation difference information storage memory 8.
The gradation information is temporarily stored in the gradation information storage memory 10. Among these, the contents of the gradation difference information storage memory 8 are read out and stored in the shift register 12 in predetermined amounts at a time.

Then, with the start of the printing operation of the printing section 6,
A print data request signal b is outputted from the printing section 6 to the shift register 12 for each pixel. Energized by this, the output c of the shift register 12 is shifted one bit at a time. If this output c, that is, the value on the differential encoding table in FIG. It is output to section 6. As a result, the printing section 6 prints dots with shading corresponding to the input gradation information. On the other hand, when the output c of the shift register 12 is "0", it is determined that the density of the pixel to be printed this time is the same as that of the previous printing, as described above. Therefore, the contents of the output register 14 are not updated, and the previously stored gradation information is outputted to the printing unit 6 again. Therefore, the printing section 6 prints dots of the same shade as the previous dots.

This will be illustrated using FIGS. 3 and 4.

Based on the gradation difference information shown in FIG. 3b and each gradation information shown in FIG. It will look like b. According to this, the densities of the th and th th to th densities for which the gradation difference information is "0" are respectively the same as the densities of the th and th prints of the previous printing. In other words, in areas where the same concentration continues like this,
Only the first gradation information is required (the fourth and sixth gradation information in FIG.
and . . . ), the amount of print information to be stored is significantly reduced. As a result, the processing speed between the upper position and the printing device can be significantly increased.

〔Effect of the invention〕

As described above, according to the present invention, print information with multi-gradation expression is formed from gradation difference information and gradation information, and printing is performed based on these information. For this reason, compared to the case where multi-gradation expression data for each pixel is handled as is, the amount of printing information per pixel required to express multiple gradations (especially 3 or more gradations), that is, per screen It is possible to provide an unprecedented multi-gradation printing device that can significantly reduce the amount of printed information and increase processing speed.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram showing an outline of an embodiment of the present invention, FIG. 2 is an explanatory diagram illustrating the data format of print information, and FIG. 3 is an explanatory diagram illustrating the data format of gradation information. , FIG. 3b is an explanatory diagram illustrating the data format of gradation difference information, FIG. 4a is an explanatory diagram illustrating the printing format of the printing section, and FIG. FIG. 4...Print information editing section, 6...Printing section.

Claims (1)

[Claims] 1. Capable of printing printing information consisting of gradation information indicating the gradation of each pixel and gradation difference information indicating whether the gradation of each pixel matches the gradation of the immediately preceding pixel. What is claimed is: 1. A multi-gradation printing device characterized by comprising a printing information editing section that edits the information and outputs it to a printing section.