JPS6048365A - Ink jet recording method - Google Patents

Abstract

PURPOSE:To obtain high density sharp recording even to a light pervious recording medium, by recording one picture element by performing lap-typing of plural ink liquid droplets in such a state that the positions thereof are mutually shifted in a predetermined amount. CONSTITUTION:An ink liquid droplet 3 is emitted to the region 1 of one picture element plural times and a plurality of ink liquid droplets are subjected to lap- typing so as to be mutually shifted in a predetermined amount to enhance recording density. The speed-up of a paper feed pace or the shift of paper feed to left and right directions may be performed by shifting the delay amount of emitting emission timing or speeding up an emitting pace. Sharp recording can be applied even to a light pervious recording medium such as a film for an overhead projector without lowering printing density.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an inkjet recording method, and more particularly to an inkjet recording method that performs recording by ejecting ink droplets onto a recording medium according to recording information.

[Prior Art] Conventionally, it has been known that the recording quality (print density, dot shape after printing, etc.) of this type of recording apparatus is greatly influenced by the physical properties of the recording medium. Therefore, in any recording device, it is recommended to use paper recommended for inkjet printers, such as a type of special paper, and the current situation is that the desired print quality can be obtained when using this paper.

Recommended paper has finely determined physical properties such as diffusion isotropy, diffusion speed, adsorption speed, and reflection density of the droplets printed on it. When recording by loading film for a projector (hereinafter referred to as OHP), the quality of the print may deteriorate significantly due to differences in the physical properties of the recording medium, or in severe cases, the print may not be fixed. there were. Therefore, attempts have been made to surface-treat OHP films and form a thin film of gelatin or PVA on the surface layer to improve fixing properties.

However, the improvement in fixing properties does not necessarily mean that the characteristics of OHP films have been improved in all respects, and they also have the major drawback of low printing density due to the fundamental difference in physical properties from plain paper described below. .

That is, OHP films, unlike paper, have low diffusivity (that is, dot spread is small), and improved fixing performance also means a decrease in the diffusivity of OHP films. Therefore, when such an OHP film is loaded into a conventional inkjet printer and recorded, the dot of each pixel becomes small, thereby reducing the printing density and resulting in a pale and blurry recording. That is, in the case of an OHP film as shown in FIG. 2, the diameter 3 of the dots ejected into a region 1 of one pixel is smaller than the dot diameter 2 in the case of plain paper shown in FIG.

Furthermore, OHP films transmit light, while conventional recording paper uses the reflected light to express images, so even ink with relatively low ink density is colored throughout (the dots are diffused). (larger and less background)
Even if the reflection density and ink density of an ink are not that low, when viewing an object with wide dot spacing and small dot diameter using transmitted light, the reflection density may seem higher.

There is a method of increasing the dye concentration in order to increase the printing density, but ``increasing the dye may cause problems such as clogging if left for a long time, dye precipitation, etc. The problem is that it cannot be done.

Also, ink is ejected multiple times to form one pixel.
There are ways to improve the recording density on P film, but when recording on plain paper, a large amount of ink is ejected, resulting in problems such as decreased resolution, ink leakage, and wrinkles on the recording paper. Further, since ejection is performed multiple times for one pixel, the recording speed is reduced.

[Objective] Therefore, the present invention aims to eliminate such conventional drawbacks, and to provide an inkjet recording method that can obtain clear recordings with high density even on optically transparent recording media such as OHP films. purpose.

[Example] Hereinafter, the present invention will be described in detail according to an example shown in the drawings.

Normally, the printer prints Y (yellow) and M (magenta).
It is equipped with four color ink ejection nozzles: , C (cyan), and Black.
, C, Black (7) When representing a monochromatic area, one dot of ink of the required color is placed in area 1 of one pixel to develop the color, and R (red), G (green)
, B (blue) by the subtractive color mixing method, dots of the required color are placed one by one to develop the color (M, C, and Y are superimposed for R).

In the present invention, we pay particular attention to the fact that when the recording medium is a light-transmissive one such as an OHP film, the dot diameter is small and the recording density is reduced as shown in FIG.
Ink droplets are ejected a plurality of times, and the ejection method uses a configuration in which the positions of a plurality of ink droplets are shifted from each other by a predetermined amount and overlapping is performed to improve the recording density.

That is, in the example shown in FIG. 3, ink droplets are ejected three times in the horizontal direction by shifting a predetermined amount in the area l of one pixel, thereby forming one pixel with three dots of diameter 3.

Further, in the embodiment shown in FIG. 4, a predetermined amount of ink droplets are ejected in each of the upper, lower, right and left directions, and the ink droplets are ejected four times in an area 1 of one pixel, recording one pixel with four dots having a diameter of 3, and in the fifth dot.
In the case of the embodiment shown in the figure, recording is also carried out at the center of the area of one pixel, and then ink droplets are ejected five times at the four corners of one pixel, and five dots with a diameter of 3 form a dot of 1. Recording pixels.

In the above-described recording method, all of the multiple printings may be shifted in the upper and lower blade directions and in the left and right directions, or may be limited to only the left and right directions and may be shifted by a predetermined amount. Further, the plurality of printings may be shifted only in the vertical direction. This can be achieved by making the paper feed pitch finer. Further, the shift in the left-right direction may be performed by shifting the amount of delay in the ejection timing, or may be performed by making the ejection pitch finer.

Next, a specific example of a configuration for recording will be described with reference to FIG.

An up/down counter 31 is connected to the CPU (central control unit) 30 that controls the recording system, and this counter counts up in synchronization with the clock from the CPU 30, and the data address corresponding to the counted value is the address. It is passed through a decoder 32. External data 34
Recorded data 35 at that address is read out from a RAM (random access memory) 33 connected to the address in synchronization with the clock. In that case, the ejection position is checked based on the signal from the carriage position detection section 36, and the driver 37 is driven.
Dot recording is performed via an inkjet unit (IJU) 38 according to the data 35 described above.

By the way, when an OHP film is detected by the OHP film detection section 39, a discharge delay is determined via the discharge delay calculation section 40, and dot recording is performed by shifting the discharge timing.

For example, let the number of times of printing with a shift be N, the dot pitch be D, the carriage speed be V, and the timing time for printing at the regular printing position of a certain dot be T (initial setting value).
Then, the discharge delay time is 1 hour from that T to mode D.
/2V+D[(Na+1)/2]/V(N+1) The dots are ejected at different times, and the dots are printed at different times. However, Na indicates the number of printing out of N repetitions, and ((Na+1)/21 indicates a Gaussian function.

Note that, as in the example shown in FIG. 3, recording is performed by setting N=3 and reciprocating the carriage three times.

In this case, the RAM is
The contents of 33 are retained and the paper is not fed by the paper feeding mechanism 41. When the number N is reached, the RAM 33 is refreshed and one sheet is sent.

On the other hand, when returning, the counter 31 is used as a down counter,
It is also possible to perform reciprocating printing by retrieving data in synchronization with the clock and printing it in the same manner as in the past. It is clear that at this time as well, the ejection delay period described above is used for T so that printing is performed as shown in FIG.

The above method is for shifting the dots left and right, but shifting the dots in the vertical direction is performed by changing the paper feeding pitch using the paper feeding mechanism 41. - When changing in the downward and horizontal directions, the delay and paper feed pitch are changed by a predetermined amount.

[Effect] As explained above, according to the present invention, when recording on a light-transmissive recording medium such as an OHP film, a plurality of ink droplets are shifted by a predetermined amount from each other and are overlaid to record one pixel. Therefore, when recording on OHP film, it is possible to obtain vivid images with increased recording density without requiring any special equipment.

[Brief explanation of drawings]

Figures 1 and 2 explain the conventional recording method. Figure 1 is an explanatory diagram for explaining the case of recording on plain paper, and Figure 2 is an explanatory diagram for explaining the case of recording on OHP film. 3 to 5 are explanatory diagrams illustrating different embodiments of the inkjet recording method according to the present invention, respectively,
FIG. 6 is a block diagram showing the circuit configuration for shifting the dots. l...Pixel area 2, 3...Dot diameter 30...C
PU 40... Ejection delay calculation section 38... Inkjet unit Fig. 1 Fig. 3 B Fig. 5vA Fig. 2 Fig. 4

Claims (1)

[Claims] In an inkjet recording method that performs recording by ejecting ink droplets onto a recording medium according to recording information, if the recording medium is transparent, multiple ink droplets are overlaid with their positions shifted by a predetermined amount from each other to record one pixel. An inkjet recording method characterized by performing the following.