JPS63297044A - Thermal recorder - Google Patents

Abstract

PURPOSE:To enhance a gradation without reducing a resolving power and a reproducibility, by a method wherein an electric conduction amount to each heating element is controlled to have (m) steps and a gradation recording with n X n X m steps is carried out. CONSTITUTION:A thermal recorder is so constructed as to perform a gradation recording with n X n X m steps by using an area gradation method where the conduction dot number in one pixel is varied for a gradation recording in combination with a dot gradation method where a conduction amount to each heating element is varied in (m) steps for controlling dot density. For example, one pixel is composed of a 2X2 dot matrix (n=2) and controlled to be in 4 steps (m=4) in dot density. Numerals provided to the respective 16 pixels represent the gradation. Each number of rows represents a gradation n X n by the area gradation method, and the number of columns represents a gradation (m) by the dot gradation method. Therefore, for example, in the case of n=2 and m=3, a 12-gradation with 1-12 steps can be realized. In this manner, a sufficiently high gradation can be obtained without sacrificing resolving power and reproducibility.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to gradation recording in printers, plotters, etc. using thermal dot heads.

(Prior Art) In this type of recording apparatus, as shown in FIG.
The so-called dot gradation method, in which the density is controlled by changing the amount of electricity applied to each pixel, and the n
An area gradation method has been used in which ×n dots are regarded as one pixel and the number of energized dots in one pixel is varied. The numbers attached to each pixel in the figure represent the gradation, and as shown in Figure 3(b)
The numbers attached to each dot indicate the order in which the number of energized dots is increased when the gradation is successively raised.

However, in the dot R1 toning method shown in Figure 2, the gradation is expressed by the shading of the dot itself, so the gradation is limited to a few steps, and if the gradation is increased beyond that, the density control method becomes complicated. In addition, there was a drawback that the reproducibility decreased and the method became unstable.

In addition, in the area gradation method, a matrix of 2 x 2 dots or 3 x 3 dots is usually used as one pixel, but there is a problem that the apparent resolution (pixel density) decreases as the gradation level is increased. . In other words, to increase the apparent resolution, it is necessary to increase the resolution (dot density) of the head itself, but within a reasonable cost range, 12 dots/dot density is possible.
The limit is about mm, and therefore, there was a problem in that the resolution deteriorated significantly in 16-gradation expression using a 4×4 matrix.

(Problems to be Solved by the Invention) In view of the above points, it is an object of the present invention to provide a recording device of this type that can improve the gradation level without deteriorating the resolution and reproducibility. It is something.

(Means for Solving the Problems) In order to achieve the above object, the thermal recording device according to the present invention uses a matrix of nxn dots as one pixel, and changes the number of JiIIIE dots in one pixel to achieve gradation. By combining the area gradation method for recording and the dot gradation method for controlling the density of dots by changing the amount of current applied to each heating element in m stages, gradation recording in n x n x m stages is performed. This is how it was done.

(.Function) According to the above configuration, a gradation corresponding to the multiplicative product of the gradation by the area Fl modulation method and the gradation by the dot gradation method can be obtained, so it is possible to obtain a gradation that is sufficient without sacrificing resolution or reproducibility. A high gradation level can be obtained.

(Example) Figure 1 shows an example of the present invention, in which one pixel is divided into two
It is composed of a matrix of x2 dots (n=2), and the density of each dot is controlled in four stages (m=4). The numbers attached to each of the 16 pixels in the figure indicate the gradation, and the number of lines is the gradation based on the area gradation method! 11nXn
, the number of columns represents the gradation m according to the dot gradation method. Therefore, for example, n=2. When m=3, there are 12 gradations from 1 to 12 in the figure.

(Effects of the Invention) The 16 gradations configured in this way could not be achieved by the conventional area gradation method using a 4 x 4 dot matrix without significantly lowering the resolution. However, according to the present invention, as mentioned above, a sufficiently high gradation level can be obtained without sacrificing resolution or reproducibility. There is an advantage.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the dot configuration of each pixel in the gradation expression of the device of the present invention, FIGS. 2 and 3 are conventional examples, and FIG. 2 is an explanatory diagram of the dot gradation method. Figure 3(a)
is an example of each pixel of 2×2 dot area gradation method, (b) is 4
This figure shows an example of a pixel configuration using the x4 dot area gradation method.

Claims (1)

[Claims] (1) A thermal head equipped with multiple heating elements is brought into sliding contact with thermal paper, and the heating elements are energized according to the image signal, and the number of energized dots in one pixel is defined as a matrix of n×n dots. In a thermal recording device that performs gradation recording by changing Features of thermal recording device.