JPS6166469A - Method of controlling gradation of thermal printer - Google Patents

Abstract

PURPOSE:To lessen time for data calculation and realize a high speed printer by receiving gradation data of n bits per dot, and enabling expression of gradation of 2<n> by decoding the data. CONSTITUTION:To make picture printing of 16 gradations by 4-bit constitution, m columns of bits are given as transfer bit column printed at a time of row unit (upper row). This transfer bit column consists of m/8 bytes. Bit columns of four steps are given as a pair of bit column of a head interface that constitutes 16 gradations. 0 bit column, 1 bit column, 2 bit column and 3 bit column are made to m/8 byte data and transferred in order of 0 bit column, 1 bit column, 2 bit column, 3 bit column, and supplied to a buffer memory of the head interface circuit side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a gradation control method for a thermal printer that converts image data such as a photograph to a TV image and prints the converted image data.

Recently, the selection of thermal recording paper that has gradation characteristics for 5 hours is being used in thermal printers that digitally convert original images of one character, one figure, etc. and then draw a pattern consisting of dots! Consideration has been given to drawing patterns by imparting light and dark gradations by selectively controlling the power applied to a printer head (thermal head) that thermally develops color by coming into close contact with the selected thermal recording paper.

The present invention adapts to such original image data and processes it in real time. In particular, this paper presents an arithmetic algorithm related to a head interface that efficiently processes image gradation expression.

[Problems that the conventional technology and invention try to solve] The so-called
Printers equipped with a line-dot type print head have a fixed thermal head element that prints in line units, and the head element writes dots while being in close contact with the thermal paper, resulting in clear, noise-free, high-speed printing. It's easy.

In order to express the gradation of image data using such a print head, signal conversion based on the gray scale of each pixel dot is required. Furthermore, the converted image signal (AD converted signal) is taken into a memory of appropriate cell capacity, and is temporarily stored, and then simultaneously processed for first and then dot line printing. By the way, the above-mentioned dot line configuration printing processing, that is, image gradation processing using a parallel interface, requires a large frame memory according to the fineness of the gradation, and the line printing time accordingly increases accordingly, making it difficult to perform real-time printing. Processing becomes difficult.

[Means for solving problems]

The above problem is.

A thermal printer according to the present invention is capable of receiving n-bit gradation data per dot and decoding the data to express 2 degrees of gradation in a printer equipped with a line-and-node print head. The problem is solved by a gradation control method.

[For production]

The present invention is to digitally convert gradation information of an original image to a thermal dot by lengthening or shortening the application time of dot coloring to print in a predetermined gray scale. That is, a logic operation circuit consisting of, for example, 4 pins (for example, 4 pins) attached to the print head is driven so that printing is performed using the printing time applied to each dot element of the head array as a parameter. It performs real-time processing of image printing.

〔Example〕

An example of a bit arrangement for printing an image of 16 gradations using a 4-bit configuration is shown in FIG. 1 and Tables 1 and 2, and will be explained based on these.

The m bit strings in the upper row of FIG. 1 are transfer bit strings that are simultaneously printed row by row by head application. The transfer bit string consists of m/8 bytes.

Each of the four bit strings below it is a bit string of a pair of head interfaces that produce 16 gradations. Each of the O bit string, 1 bit string, 2 bit string, and 3 bit string is converted into m/8 byte data, and is sequentially converted into a 0 bit string, a 1 bit string, and a 1 bit string.
Bit string, 2 bit string.

and are transferred in the order of 3-bit strings. Therefore, on the head interface circuit side that receives data transfer (.../8
) A buffer memory of 4 bytes is attached.

Table 1 shows the logic operation algorithm performed by the buffer memory based on the gradation data having a 4-bit configuration.

(Table-1) -” 0bit 1bit 2b
it 3bit100ROOR○ OR○ 2 00ROORO 30^ND ○ OR○ OR0 4Q OR○ 5 00ROAND ○ OR○6
0 ANDQORQ7 0 AND 0AND
QOR○8
0 AND○9 0 Kano ○ OROAN
D ○10 0 0ROAND ○
11 0AND ○ ORO＾NO0120AND
O 1300RQAND Q AND ○14
0 ^ND OAND ○15
0AND 0AND OAND ○ An example of data calculation in the buffer memory using such an algorithm is shown below.

Table 2 shows, for example, transfer data that provides 16 gradations for the bit string corresponding to part A in FIG.

(Table-2) 0 bit: 101010101 bit: 1
1001100 2 bits: 11110000 3 bits: l 1111111 Table 3 is calculation data that gives the head operating time due to the transfer of the gradation signals in Table 1 and Table 2.

(Table-3) 1 1111111115.
1 0 0 0 0 0 0 0↑
↑ Number of repeated printing: 15 times start, -1111111, -8 times start In other words, the thermal head operation lengthens or shortens the application time according to the 2' = 16 gradation to print shading. This will be done by repeated activation of .

FIG. 2 is a flowchart for driving the printer head by inputting the 4-bit tone data.

In the description of the configuration example of the gradation data.

Although the example of printing with 16 gradations using 4-bit data has been described, this is, for example, 8 bits (28 gradations).

It can be further expanded to 16 binoto...

Accordingly, the cell capacity of the sofa memory on the print head side has been increased to (m/8) x 8 + (m/s) x 16. ,-・
・Take measures by increasing the amount.

〔Effect of the invention〕

According to the gradation control method of the present invention described in detail above,
There is an advantage that the gradation representation of the original image data requires a relatively small memory capacity, and therefore the time required for data calculation is also short, and a high-speed printer can be realized.

[Brief explanation of drawings]

FIG. 1 is an embodiment of a transfer bit string for gradation control of m/8 byte configuration for line printing according to the present invention. Figure 2 shows the flowchart that drives the printer head 1
Mouthhole 2f)

Claims (1)

[Claims] A thermal printer equipped with a line-dot printing head, which receives n-bit gradation data per dot and decodes the data to make it possible to express 2^n gradations. Printer gradation control method.