JPH01198367A - fever head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat generating head, and particularly to a heat generating head suitable for halftone recording.

[Conventional technology]

Conventionally, regarding a heat generating head suitable for halftones, Japanese Patent Application Laid-open No. 5
As described in No. 4-16194.7, one pixel was constituted by a single heating resistor having a current concentration portion and having an elongated shape in the recording direction of the heating head. By providing a current concentration part in the heat generating resistor, the high temperature area on the heat generating resistor changes depending on the applied energy, so that it is possible to perform halftone recording in which the area of the recorded dots transferred is controlled by the high temperature area. In addition, by making the heating resistor elongated in the recording direction, the temperature gradient in the recording direction is relatively gentle even during high-speed recording, so the time it takes for the high temperature area to pass over the coloring area or ink sheet becomes longer. In the case of a single dot, halftone recording with a stable recording dot area can be realized.

[Problem to be solved by the invention]

The configuration of a recording apparatus using a heat generating head will be explained with reference to FIGS. 6 and 7. FIG. 6 is an electrical block diagram showing the image source 18. The halftone control circuit 192 is composed of a heating head 2o and a microcomputer (not shown) that controls signals and mechanical parts. The image gradation information stored in the image source 18 is transferred line by line to the halftone control circuit, and the heat generating head is adjusted to 0N10F according to the recording characteristics.
The signal is converted into an F signal and causes the heat generating resistor of the heat generating head 2o to generate heat. The operation of the mechanism in response to the heat generated by the heat generating head 20 will be explained with reference to FIG. The ink sheet 21 and the image receiving paper 22 are sandwiched between a heating resistor 23 on the heating head 2o and a platen roller 24. Heat generating resistor 23
generates heat in accordance with the image information, melts the ink on the ink sheet 21, and forms one line of image on the image receiving paper 22. Thereafter, this operation is repeated in accordance with the rotational speed of the platen roller 24 to complete the image.

However, in the above-mentioned conventional technology, good halftone recording characteristics can be obtained when one dot is recorded with the heat-generating head stopped, but when recording is performed while the heat-generating head is moved,
In particular, when recording at an intermediate density or higher, the dots recorded in the previous line overlap, so no consideration has been given to the deterioration in image quality caused by the inability to maintain the independence of the dots.

An object of the present invention is to provide a heat-generating head that can maintain pixel independence from low density to high density even under high-speed printing conditions and has excellent halftone printing characteristics.

[Means to solve the problem]

The above purpose is to construct one pixel by arranging a plurality of heating resistors, which are elongated in the recording direction and have excellent halftone recording characteristics when recording one dot, by arranging them approximately in parallel, by providing a current concentration part in a part of the heating resistors. This is also achieved by making the interval between adjacent heating resistors within a pixel smaller than the interval between adjacent heating resistors between pixels.

[Effect]

By reducing the elongated heating resistors in the recording direction to similar shapes and arranging them in parallel to form one pixel, the halftone recording characteristics during one tod recording are good, without impairing the good halftone characteristics. In addition to making it possible to obtain sufficient saturation density, the length of the heating resistor in the recording direction can be shortened to less than the pixel pitch, which shortens the dot length in the recording direction and prevents dots from overlapping with the recorded dots of the previous line. Dot independence can be maintained. Furthermore, by making the interval between adjacent heating resistors within a pixel smaller than the interval between adjacent heating resistors between pixels, the amount of ink bridges that occur between dots within a pixel is reduced, and ink between adjacent pixels is reduced. Since the occurrence of bridges can be suppressed, halftone recording with excellent recording density stability and dot independence can be maintained up to a high recording density.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

The basic configuration is almost the same as a conventional heating head for recording halftones, but two heating resistors 2a and 2b with a current concentration part in the center are arranged between counter electrodes 1, and pixels are configured. The difference is that the distance d1 between the two heating resistors is arranged to be shorter than the distance d2 between the heating resistors of adjacent pixels. The recording density characteristics of the resistor shape of this example will be explained with reference to FIGS. 2 to 4.

FIG. 2 shows the resistor shape and its recording density characteristics when the length of the heating resistor and the minimum width of the heating resistor which determines the minimum recording density are constant. The recording density characteristic 5c of the heating resistor 5 has a gradual change in density with respect to applied energy and good halftone recording characteristics, but there is a problem that the saturated recording density is low because the area of the heating portion is small. on the other hand,
In the recording density characteristics 6c and 7c of the heating resistors 6 and 7, the low density recording density characteristic is the recording density characteristic 5c of the heating resistor 5.
Furthermore, although the saturation density is sufficiently high, since the temperature gradient in the recording direction on the heating resistor is large, the γ of recording at intermediate density is high, making it difficult to achieve multi-gradation recording.

Further, FIG. 3 shows recording density characteristics 5c, 8c, and 9c of similar heating resistors 5, 8, and 9. The recording density characteristics 8c and 9c of the heating resistors 8 and 9, which have twice and triple the area of the heating resistor 5, respectively, have a minimum recording density higher than the characteristic 5c, and moreover, in the middle and high density region, It shows a characteristic of high density gradient caused by image quality deterioration due to overlap with recorded dots. This phenomenon becomes noticeable when a heat-melting type ink seal capable of high-speed recording is used.

FIG. 4 shows recording density characteristics 5c, 10c, and llc when the number of heat-generating resistors constituting one pixel is changed to three in parallel. Here, the heating resistor 10 and the recording density characteristic 10c
are the shape and characteristics of this example. The heating resistor 10 has a large resistor area in a pixel compared to the heating resistor 5, so that sufficient saturation density can be obtained, and the heating resistor 10, which is long in the recording direction and has excellent halftone recording characteristics, is combined in the pixel. As a result, stable halftone recording characteristics can be obtained from low density to high density. In addition, the recording density characteristic 11c of the heating resistor 11 in which three heating resistors are arranged in parallel has a higher saturation density and recording density characteristic 1, although the minimum recording density increases slightly.
Almost the same characteristics as 0 can be obtained.

By making the interval between adjacent heating resistors within a pixel smaller than the interval between adjacent heating resistors between pixels, ink bridging within the pixel is facilitated. This results in
The enlargement of the dot area at intermediate density mainly develops within the pixel. Because the distance between the resistors within a pixel is short, the amount of ink bridges that occur can be kept to a small amount, and ink bridges between pixels can be prevented even at high recording densities, resulting in stable recording density and dot independence. Halftone recording with excellent quality can be maintained up to high recording density.

According to this embodiment, it is possible to create a resistor shape that achieves both high gradation recording characteristics and prevention of overlapping of recording dots of the previous line and adjacent pixels, so it has excellent halftone recording characteristics even during high-speed recording. A heat-generating head can be realized.

FIG. 5 shows another embodiment of the invention. The basic configuration is the first
This embodiment is almost the same as the embodiment shown in the figure, except that one of the opposing electrodes is made independent for each resistor. In FIG. 5(A),
One ends of the heating resistors 2a' and 2b' are separated and connected to newly provided individual electrodes 12a' and 12b'. The individual electrodes 12a' and 12b' are respectively connected to output terminals of an energization control driver (not shown). In the configuration of this embodiment, an example of heat generation control when recording halftones is shown in FIG. 5(B). In this figure, the dots on the right side have higher recording density. The recording dot 13 records the lowest density, and one heating resistor 2a' is energized with the energy necessary to record the minimum dot 1- that can be stably recorded. By increasing the energy applied to the heating resistor 2a', it is possible to increase the recording density as in the recording dots 14. Minimum dot 13 for stable recording
When the dot area has doubled, both heating resistors are energized and the two smallest dots are recorded. Thereafter, by increasing the applied energy, the recording density can be increased. Furthermore, when applied to full-color recording, during low-density recording using one heat-generating resistor, by selecting the heat-generating resistor depending on the color, a reduction in brightness due to color mixing of inks can be prevented.

According to this embodiment, since the two heating resistors constituting one pixel can be individually controlled, it is possible to realize a heating head that has particularly excellent recording characteristics in a low density region.

〔Effect of the invention〕

According to the present invention, a sufficient saturation density can be obtained even if the length of the resistor is shorter than that of the pixel, so it is possible to use a heating resistor that is long in the recording direction and has good halftone recording characteristics. This prevents the recording dots of the previous line and adjacent pixels from overlapping, so even under high-speed recording conditions, the heat-generating head has excellent halftone recording characteristics that maintain dot independence from low density to high density. realizable.

[Brief explanation of the drawing]

Figure 1 is a plan view showing one embodiment of the present invention, Figures 2 and 3 are
4 is a characteristic diagram showing the effects of the present invention, FIG. 5 is a plan view and characteristic diagram showing another embodiment of the present invention, FIG. 6 is a block diagram showing the electrical configuration of the recording device, and FIG. FIG. 7 is a side view showing the operation of the recording apparatus. 1... Counter electrode, 2a, 2b, '2a', 2b
' , 5°6.7, 8, 9, 10.11... Heat generating resistor, 3... Pixel, 4... Recording direction, 5c, 6c, 7
c, 8c. 9c, 10c, llc...recording characteristics, 12...a'
. 12b'...Individual electrode, 13, 14, 15, 16°1
7... Recording dot, 18... Image source, 19... Halftone control circuit, 20... Heat generating head, 21... Ink sheet, 22... Receiving paper, 23... Heat generating resistor body,
24...Platen roller.

Claims (1)

[Claims] 1. In a heat generating head in which a plurality of counter electrodes are arranged on an insulating substrate and a heat generating resistor having a long shape in the recording direction of the heat generating head is formed between the counter electrodes, the plurality of heat generating resistors A heat-generating head characterized in that the heat-generating resistors are arranged substantially in parallel to form one pixel, and the interval between adjacent heat-generating resistors within a pixel is smaller than the interval between adjacent heat-generating resistors between pixels. 2. The heating head according to claim 1, wherein the outer shape of the plurality of heating resistors constituting one pixel is shorter than the pixel pitch. 3. The heating head according to claim 1, characterized in that a current concentration portion is provided in a part of the heating resistor. 4. The heat generating head according to claim 1, characterized in that a common electrode is used to control energization of the plurality of heat generating resistors constituting one pixel. 5. The heat-generating head according to claim 1, wherein the electrodes for controlling energization of the plurality of heat-generating resistors constituting one pixel are independent for each heat-generating resistor.