JPH06305163A - Ink jet printer - Google Patents

Abstract

PURPOSE:To perform density gradation control of two or more stages by mixing the usual density ink and variable density ink of an ink jet printer. CONSTITUTION:An ink jet printer has ink jet nozzles 2A, 2B equipped with pressure chambers 8A, 8B injecting at least two kinds of inks to recording paper 10 and jet pressure control parts 4A, 4B, an ink cartridge 3 storing usual density ink and a variable density ink cartridge 1 storing inks different in density.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer, and more particularly, to an ink jet printer suitable for printing a character or an image to be printed with multiple gradations.

[0002]

2. Description of the Related Art Generally, an ink jet printer is often a pressure pulse type in which ink in a pressure chamber is pressurized and ink is pushed out from a nozzle, which is also called an impulse jet printer. As shown in the configuration diagram of FIG. 3, this type of printer has an ink cartridge 5 that contains ink of a prescribed concentration, a single-chamber pressure chamber 8 that temporarily holds the pressurized ink at a constant pressure, and records ink. There are a nozzle 2 that ejects onto the paper 10 and an ejection pressure control unit 4 that controls the pressure applied in the pressure chamber 8. In general, the ejection pressure control unit 4 supplies a pulse voltage to a piezoelectric element or the like to intermittently apply vibration to eject ink. Such an ink jet printer is used when printing only characters having a constant density. However, in the case of performing color display of an image having an intermediate density such as a photograph or a natural image, there is a method of expressing an intermediate tone by using an area gradation method such as the dither method shown in the explanatory diagram of FIG. That is, in the area gradation method, for example, 16 dots of 4 × 4 dots are used to represent one pixel, and the area occupied by the ink print dot portions 20A to 20G among these 16 dots is increased stepwise. . That is, the white non-printing dot portions 21A to 21G and the ink printing dot portions 20A to 21G.
Change the ratio with 20G step by step to visually perceive light and shade. However, in this area gradation method, the distinction between white and ink portions is expressed in a predetermined multi-gradation by scanning of the ink jet section and ink ejection, and therefore the bleeding of the ink dot section appears and the resolution of the entire image is reduced. It becomes unclear. Furthermore, if the nozzle is sharpened and the resolution is increased, mechanically 1
Since it is necessary to scan a large number of times with a large number of dots of 6 dots or more as one pixel, a considerably long printing time is required.

[0003]

Since the conventional ink jet printer uses the area gradation method for expressing halftone, it has a drawback that the resolution of the entire image is lowered. If the resolution is further increased, there is a drawback that the printing time becomes long.

An object of the present invention is to control the ink density in a plurality of steps without using the area gradation method.
An object of the present invention is to provide an ink jet printer that can express multi-tone gradation.

[0005]

The ink jet printer of the present invention comprises an ink cartridge for storing ink having a first density, a pressure chamber, a pressure control unit for controlling the ejection pressure of this pressure chamber, and an ink droplet ejection nozzle. A first injector having the same, an ink cartridge having a second concentration for accommodating ink, a pressure chamber, a pressure controller for controlling the ejection pressure of the pressure chamber, and a second having an ink droplet ejecting nozzle.
And an injector for controlling the first and second injectors in accordance with the shading of the screen.

[0006]

The present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of the first embodiment of the present invention. In the embodiment shown in FIG. 1, a recording paper 1, nozzles 2A and 2B for respectively ejecting inks of two different densities, an ink cartridge 3 for containing ink of normal density, and a variable density ink for containing inks of different densities Cartridge 1
And pressure chambers 8A and 8B for pressurizing ink, which correspond to the nozzles 2A and 2B, respectively, and ejection pressure control units 4A and 4B, which control the ejection pressures of the pressure chambers 8A and 8B, respectively. Although not shown, these inkjet units are attached to one carriage and are indicated by arrows Ye or Y.
Reciprocates in the direction of r. Recording paper 1 when scanning of one line is completed
Since 0 is moved in the direction orthogonal to the Ye or Yr direction, one image is formed. When printing a halftone as shown in the photograph, the ejection pressure control units 4A and 4B control the ejection amounts of the ink of the ink cartridge 3 and the variable concentration ink cartridge 1 according to the required density. Thus, the pressure chambers 8A and 8B are controlled to eject a desired amount of ink droplets from the nozzles 2A and 2B. For example, the pressure of the ejection pressure control unit 4B is squeezed in the dark color gradation, and conversely, the pressure of the ejection pressure control unit 4A is squeezed in the light color gradation and the ink is ejected from each nozzle. Each of the ejected ink droplets has a mixture of two kinds of densities on the recording paper 10 to obtain a density of a required gradation. The relationship between the control values of the ejection pressures, the gradation values of the densities, and the two types of ink densities used is stored in a computer (not shown) in a predesigned table. The computer controls the injection pressure control units 4A and 4B according to the control values of the injection pressure corresponding to the concentration information of each part of the screen.
To control.

Next, a second embodiment of the present invention will be described with reference to FIG. The embodiment of FIG. 2 is the same as the first embodiment, the ink cartridge 3, the variable density ink cartridge 1, the mixing chamber 7 for mixing the normal density ink of the ink cartridge 3 and the light color ink of the variable density ink cartridge 1, the mixing amount. A pressure chamber 8 that pressurizes and holds the mixed ink by the ejection pressure control unit 4, a nozzle 2 that ejects the mixed ink, and a recording paper 10. When printing an intermediate density, a variable density liquid agent for changing the normal density ink is injected and mixed in the mixing chamber 7.
The mixed liquid is jetted from the nozzle 2 toward the recording paper 10 by the jet pressure control unit 4. In this case, the mixture control unit 9 is controlled according to the gradations of the shade of the screen to change the density of the mixed ink. If the density distribution of each part of the screen is clearly separated (two-color printing, etc.), it is also possible to print one scan at a time according to the gradation of the density by setting the number of times the inkjet part is scanned to multiple strokes. Is.
In each of the first and second embodiments, the gradation is divided into several gradations according to the image to be printed, and the mixing ratio of the ink and the liquid agent that changes the ink density at each gradation is calculated in advance, Determines the ejection amount of the liquid agent that changes the ink concentration. It is also possible to use the density gradation control and the area gradation method of this embodiment together.

[0009]

The ink jet printer of the present invention can control the density gradation by providing the ink cartridges of at least two kinds of density and the ejection pressure control section of each ink. Therefore, there is an effect that a screen having multi-tone density can be realized with a relatively simple structure. Especially 2
In the case of a color or a color having a clear color classification of three-color printing, there is an effect that a relatively simple color image can be realized by replacing the corresponding ink cartridge.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional inkjet printer.

FIG. 4 is an explanatory diagram of a general area gradation method.

[Explanation of symbols]

 1 Variable Density Ink Cartridge 2, 2A, 2B Nozzle 3, 5 Ink Cartridge 4, 4A, 4B Injection Pressure Control Section 7 Mixing Chamber 8, 8A, 8B Pressure Chamber 9 Mixing Control Section 10 Recording Paper

Claims (2)

[Claims] 1. A first ink cartridge for storing ink having a first concentration, a pressure chamber, a pressure control unit for controlling the ejection pressure of the pressure chamber, and an ink droplet ejection nozzle.
And an ink cartridge for accommodating ink having a second concentration, a pressure chamber, a pressure controller for controlling the ejection pressure of the pressure chamber, and a second injector having an ink droplet ejecting nozzle. An ink jet printer characterized in that the first and second injectors are controlled in accordance with the shading of a screen. 2. A first ink container having a first density for storing ink.
An ink cartridge, a second ink cartridge for storing ink having a second concentration, a mixing control unit for controlling a flow rate provided at the output of at least one of the first and second ink cartridges, A mixing chamber that mixes the ink that has passed through the mixing control unit with the ink of the other ink cartridge, and one injector that controls the ejection pressure of the ink from the mixing chamber and ejects a predetermined amount of ink droplets. Inkjet printer characterized by.