JP2752472B2 - Ink jet recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus, and more particularly to an ink jet recording apparatus that records a multicolor image using ink droplets of a plurality of colors.

[Prior Art] FIG. 6 shows a subtractive color mixing method for expressing multiple colors, and FIG. 7 shows an operation mode of a color ink jet recording apparatus using a reducing and mixing method.

As shown in FIG. 6, the three primary colors of yellow (hereinafter abbreviated as Y), magenta (hereinafter abbreviated as M), and cyan (hereinafter abbreviated as C) are red (hereinafter abbreviated as R), respectively. ), Green (hereinafter abbreviated as G), and blue (hereinafter abbreviated as B) in complementary colors. Therefore, as shown in FIG. 7, in a color ink jet recording apparatus, generally, R is formed by overlapping Y and M, G is formed by overlapping Y and C, and B is formed by combining C and M. It is formed by overlapping. In addition, when three colors of Y, M, and C are overlapped, black (hereinafter, abbreviated as Bk)
In principle, these three primary colors are sufficient.
Bk by color mixing becomes cloudy. For this reason, it is common to have Bk ink separately.

By the way, in the case of a transfer type color thermal printer other than the color ink jet recording apparatus, for example, when three colors of Y, M, and C are overlapped to form Bk, the reflection characteristics are different depending on the order of overlapping. In this order, Y, M,
When the layers are superposed in the order of C, the reflectance becomes relatively low over the entire wavelength range in the order of Y, M, and C, and the color becomes darker. For this reason,
In the case of a transfer type color thermal printer, a method of superimposing colors in the order of Y, M, C is generally adopted. In this case, according to the experiment of the present inventor, black superimposed in the order of Y, M, C becomes bluish black, and black superimposed in the order of C, M, Y becomes yellowish black. That has been confirmed. Since this transfers the solid ink from the ink ribbon onto the recording paper, it seems that the solid ink depends on the reflection characteristics of C and Y, respectively, to be transferred last.

However, in the color ink jet recording apparatus, black superimposed in the order of Y, M, and C becomes yellowish black, and black superimposed in the order of C, M, and Y becomes bluish black. This is a phenomenon opposite to that of the transfer type color thermal printer described above. This is because, in a color ink jet recording apparatus, since an image is formed by absorbing ink droplets on a recording sheet, the dot diameter on the recording sheet changes due to a change in the ink absorption capacity of the recording sheet. That is, in the case of mixed color recording of two or more colors,
The ink droplets ejected first on the paper spread more on the paper than the ink droplets superimposed later,
This is because the dot diameter increases. Therefore, in a color ink jet recording apparatus, the black obtained by superimposing colors depends on the size of the Y and C dot diameters which are first ejected onto a sheet.

[Problems to be Solved by the Invention] However, in the above-described color ink jet recording apparatus, when recording image information such as figures, characters, and symbols, for example, when recording an image that can be expressed by one color ink. In general, when printing an image expressed by superimposing two color inks, the amount of ink to be printed on the recording paper is different.

As shown in FIG. 8, for example, when the lining color (hereinafter referred to as background color) portion 82 is recorded in Y color and the outer background color (hereinafter referred to as fore color) portion 81 is recorded in B color as “+”, B Color recording section,
In other words, the two-color recording unit in which the M color and the C color are superimposed requires a larger amount of ink to be ejected than the other one-color recording units. This ink and the ink of the adjacent recording unit, that is, Y
If the color is unfixed, the ink in this portion may affect each other and cause ink bleeding in the adjacent portion 83 shown by oblique lines in FIG. 8, which significantly impairs the resulting image quality. There was a problem.

Such a problem is generally caused by the ink absorbing ability of the recording medium, and is a problem that occurs particularly when the designated paper is not used. That is, the above problem is relative to the ink absorbing ability of the recording medium used, and is not limited to the image in which the two-color recording unit and the one-color recording unit are mixed as illustrated in FIG. When a recording medium having poor absorption capacity is used, there is a problem that occurs between single-color recording sections, and conversely, when the relative absorption capacity is high, between multicolor recording sections of two or more colors.

Therefore, the present invention eliminates the above-described problem, and makes the pixel dots forming the color boundary portions white without ink, so that both inks adjacent to each other at the color boundary portions do not affect each other. It is therefore an object of the present invention to provide an ink jet recording apparatus which can obtain a high quality image even if the recording medium has a relatively low ink absorbing ability.

Means for Solving the Problems According to the present invention, in an ink jet recording apparatus for recording an image on a recording medium by ejecting recording droplets of a plurality of colors based on image information, the present invention defines the image by a difference in color. Recording control means for performing processing for converting image information corresponding to a predetermined area along a color boundary to be information that does not eject the recording liquid droplets.

[Operation] According to the above configuration, a predetermined area along the color boundary is not so-called a blank area, in which ink is not applied. Therefore, inks in both areas adjacent to the color boundary affect each other and bleed. Etc. can be prevented.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic perspective view showing an example of the configuration of a color ink jet recording apparatus that discharges ink using thermal energy generated by an electrothermal transducer as discharge energy as a preferred embodiment of the present invention. It is.

In FIG. 1, a recording medium 1 such as a sheet of paper or a plastic sheet is supported by transport rollers 2 and 3 composed of a pair of rollers disposed above and below a recording area, and is transported by a transport roller 2 driven by a sheet feed motor 4. Arrow A
Conveyed in the direction. A guide shaft 5 is provided in front of the transport rollers 2 and 3 in parallel with the transport rollers. The carriage 6 is reciprocated in the direction of arrow B via the wire 8 by the output of the carriage motor 7 along the guide shaft.

On the carriage 6, a recording head unit 90, which is an ink jet head of the above-described type, is mounted. This recording head unit 90 is for recording a color image,
Arranged in the scanning direction, cyan (C), magenta (M),
Four recording heads 9 provided corresponding to inks of yellow (Y) and black (Bk), that is, 9A, 9B, 9C, 9
Made of D. On the front surface of each recording head 9, that is, on the surface facing the recording medium 1 at a predetermined interval (for example, 0.8 mm), a recording unit in which a plurality of (for example, 32 or 128) ink ejection ports are arranged in a vertical line. Is provided.

FIG. 2 schematically shows a partial vertical cross section of an ink ejection section of the above-described print head 9 (the same applies to any of the print heads 9A to 9D).

2, a surface of the recording head 9 facing the recording medium 1 is provided with a plurality of ink ejection ports 10 at a predetermined pitch in the vertical direction.
Is formed. The electrothermal transducer 11 provided in the ink liquid passage communicating with each ink ejection port 10 is driven (electrically heated) based on the dot information to generate air bubbles 11A in the ink. Due to the accompanying pressure fluctuation, flying ink droplets 12 are formed, and recording is performed while attaching ink dots to the recording medium 1 in a predetermined pattern.

Each recording head 9 is mounted with a circuit board of a driving circuit (driver) 29 (see FIG. 1) for performing the above-described driving.

Referring again to FIG. 1, the control circuit (CP
U) and a control unit including a ROM, a RAM and the like attached thereto are formed on a control board 15, and this control unit receives command signals and data signals (recording information) from a host device 7 such as a computer. Then, a drive voltage (heat voltage) of the electrothermal transducer is applied to each of the recording heads 9A to 9D via the heat driver 6 shown in FIG. 2 together with drive sources such as various motors.

An operation panel 160 attached to an outer case (not shown) of the recording apparatus has an online / offline switching key 1.
6A, line feed key 16B, form feed key 16C,
In addition to a key setting section such as a recording mode switching key 16D, a display section including some alarm lamps such as an alarm lamp 16E and a power lamp 16F is provided.

FIG. 3 shows a circuit configuration example of a control system of the ink jet recording apparatus shown in FIG.

In FIG. 3, a CPU 21 in the form of a microprocessor
Are connected to a host device 7 such as a computer via an interface 22, and read from the host device 7 into a data memory 23, a recording information signal, and a program memory 24 in a ROM form or a RAM form. The recording operation is controlled based on a program or data stored in the working memory 25 or the like.

The CPU 21 controls the carriage motor 7 (see FIG. 1) and the sheet feed motor 4 (see FIG. 1) via the output port 26 and the motor driver 27, and based on the recording information stored in the data memory 23. Head drive circuit
The recording head 9 is driven via 29.

That is, the CPU 21 performs the recording control unit b shown in FIG.
Is configured.

Reference numeral 30 in FIG. 3 (not shown in FIG. 1) denotes a sheet sensor, which detects whether or not the recording medium 1 exists between the transport rollers 2 and 3 (see FIG. 1). And input port
A detection signal is transmitted to CPU 21 via 31.

Output from each of the operation keys 16A to 16D (see FIG. 1) on the operation panel 160 is transmitted to the CPU 21 through the input port 32.
To the alarm lamp 16E and power lamp 16F
A control signal is supplied to the warning lamp through the output port 36.

Reference numeral 33 in FIG. 3 denotes a DIP (dip) switch provided on the bottom portion of the exterior of the apparatus, and the output is transmitted to the CPU 21 via the input port 34.

In FIG. 3, the power supply circuit 28 outputs a logic drive voltage VCC (5) for operating the control logic circuit.
V), various motor drive voltage VM (30V), reset voltage RESE
T, a heating voltage (head voltage) VH (25 V) for heating the electrothermal transducer 11 of each recording head 9 and a backup voltage VDDH for protecting the recording head 9 are output.

The heating voltage VH is applied to the recording head 9, the backup voltage VDDH is applied to the head driving circuit 29 and the recording head 9,
Each is applied.

The flowchart shown in FIG. 4 relates to one embodiment of the present invention and shows an example of the processing procedure of the CPU 21 when receiving recording data. This processing procedure is stored in advance in the program memory 24 shown in FIG.

The CPU 21 first determines the identification information of the recording medium set by, for example, the Dip switch 33 by taking in the state of the switch 33 via the input port 34 after the control unit is initialized (step S100) such as when the power is turned on. However, if the recording medium is designated paper, normal data reception processing is performed.
The processing after step S102 according to the embodiment of the present invention is performed. (Step S101).

In the present embodiment, a description will be given assuming that the identification information indicating whether the recording paper to be used for recording is designated paper or non-designated paper is provided by a Dip switch. (Not shown), a designated paper sheet cassette insertion presence / absence switch (not shown), a designated paper roll paper device switch (not shown), or the like, and processing may be performed according to the identification information of these switches. Good.

Next, the CPU 21 is connected to the host device 14 connected to the recording apparatus.
(Step S1) while monitoring the control command and recording data input from the interface 22 via the interface 22.
02). Here, in this example, it is assumed that the color command setting from the host device 14 is executed according to the following specifications. That is, ESC F n1 where ESC F indicates a foreground color setting command, and n1 indicates a foreground color specified by a 1-byte binary parameter. Foreground colors include black, blue, red, magenta, green, cyan,
There are eight colors, yellow and white. Note that when power is turned on, black is automatically set. The specification of the color command setting is ESC B n2, where ESC B indicates that this is a background color setting command, and n2 indicates the background color specified by a 1-byte binary parameter. The specified color is the same as n1.
White is set.

In this embodiment, for simplicity of explanation, ESC F
n1 and ESC B n2 shall be continuously received.

Next, the CPU 21 determines whether there is a color command in step S103. If there is a color command, Y, M, C, and Bk buffers for reception of the fao color and the background color are set in the data memory 23 in steps S104 and S105.

In step S106, as described in detail in FIG. 5, the received print data is developed in Y, M, C, B and a print buffer. If it is determined in step S103 that there is no color command, the default black, that is, the received data, is expanded in the Bk buffer.

In step S107, it is determined whether or not to start printing based on whether or not all of the specified print data (for example, one scan) has been developed. If the determination is negative, the process returns to step S102 to receive the next print data. Thereafter, the operations of S102 to S107 are repeated.

If it is determined in step S107 that printing has been started, the color inkjet printer starts printing.

FIG. 5 is a flowchart of a process showing details of the processes of steps S104 and S105 in FIG. 4, and the color boundary portion is blanked out by this process. In this embodiment, a description will be given assuming that buffer areas for Y, M, C, and Bk are provided for each of the foreground color and the background color.

When the background color specified in step S201, for example, the Y color, is specified, the CPU 21 writes all “1” into the Y buffer for the background color. Next, when, for example, the Bk color is designated as the foreground color, the area corresponding to the character "+" shown in FIG. 8 of the Y buffer written in step S201 is blanked, that is, "0" is written (step s202). . Further, white areas, that is, “0” are written in the area of the Y buffer corresponding to the oblique lines in FIG. 8, as in step S202 (step S203). Step S2
Upon completion of the whitening process of 02 and step S203, the area "1" corresponding to the character "+" in FIG. 8 in the foreground Bk buffer is written (step S204).

In the above embodiment, as shown by the hatched portion in FIG. 8, the region where whitening is performed is one example of the pixel dot along the color boundary, but the application of the present invention is not limited to this. A desired area can be set in consideration of the amount of ink to be ejected.

The present invention brings about an excellent effect particularly in a recording head and a recording apparatus of a bubble jet method among ink jet recording methods. This is because according to such a method, it is possible to achieve a higher density and a higher definition of the recording, and it is expected that the fixing pattern will be further slowed down by the recording pattern.

As for the representative configuration and principle, it is preferable to use the basic principle disclosed in, for example, US Pat. Nos. 4,723,129 and 4,740,796. This method can be applied to any of the so-called on-demand type and continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or liquid path holding the liquid (ink). Applying at least one drive signal corresponding to recording information and providing a rapid temperature rise exceeding nucleate boiling to the electrothermal transducer, thereby causing the electrothermal transducer to generate heat energy, and This is effective because film boiling occurs on the heat-acting surface of the liquid, and as a result, bubbles in the liquid (ink) corresponding to the drive signal one-to-one can be formed. The liquid (ink) is ejected through the ejection opening by the growth and contraction of the bubble to form at least one droplet. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of a liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable.
US Pat. No. 4,446,335 describes this pulse-shaped drive signal.
Those described in Japanese Patent No. 9 and No. 4345262 are suitable. Further, if the conditions described in US Pat. No. 4,436,124 of the invention relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As a configuration of the recording head, another heat-acting portion of a combination configuration (a linear liquid flow path or a right-angled liquid flow path) of a combination of a discharge port, a liquid path, and an electrothermal converter as disclosed in the above-mentioned specifications. A configuration using U.S. Pat. No. 4,558,333 and U.S. Pat. No. 4,459,600, which disclose a configuration in which is disposed in a bending region, is also included in the present invention. In addition, Japanese Unexamined Patent Publication No. 59-123670 discloses a configuration in which a common slit is used as a discharge portion of an electrothermal converter for a plurality of electrothermal converters, and an opening for absorbing a pressure wave of thermal energy is provided. The effect of the present invention is effective even if the configuration is based on JP-A-59-138461, which discloses a configuration corresponding to a discharge unit. That is, recording can be performed reliably and efficiently regardless of the form of the recording head.

Further, even in the case of the serial type as in the above example, a replaceable chip-type recording head, which can be electrically connected to the apparatus main body or supplied with ink from the apparatus main body by being attached to the apparatus main body, The present invention is also effective when a cartridge type recording head provided integrally with the recording head itself is used.

Regarding the type or number of print heads to be mounted, for example, in addition to one provided for each single color ink, a plurality of print heads are provided corresponding to a plurality of inks having different densities. It may be.

In addition, the form of the ink jet recording apparatus of the present invention may be used as an image output terminal of an information processing apparatus such as a computer, a copying apparatus combined with a reader or the like, or a facsimile apparatus having a transmission / reception function. It may be something.

[Effects of the Invention] As is clear from the above description, since a predetermined area along a color boundary is a so-called white area where ink is not applied, the ink in both areas adjacent to the color boundary is affected. It is possible to prevent the occurrence of ink bleeding or the like.

As a result, the ink (recording liquid) of the recording medium used for recording
Irrespective of the difference in absorption capacity relative to the image, a high-quality image can always be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration example of a color inkjet printer to which the present invention is applied, FIG. 2 is a partially enlarged longitudinal view showing details of a main part of the recording head of FIG. 1, and FIG. FIG. 4 is a block diagram showing a configuration example of a control system of the color ink jet printing apparatus shown in FIG. 4. FIG. 4 is a flowchart showing an example of a control processing procedure when print data is received, according to an embodiment of the present invention. 4 is a flowchart showing a data writing process of a buffer for a background color and a foreground color in the process shown in FIG. 4. FIG. 6 is an explanatory diagram showing a color specification state when recording is performed by a color inkjet printer by a subtractive color mixing method. FIG. 7 is a schematic diagram showing a recording state when recording is performed by a color inkjet printer by the subtractive color mixing method, and FIG. 8 is a schematic diagram showing a recording screen in a pixel dot configuration. . 1 ... printing medium, 6 ... carriage, 7 ... carriage motor, 9, 9A, 9B, 9C, 9D ... printing head, 10 ... discharge port, 11 ... electrothermal conversion element, 16 ... operation keys , 21 ... CP
U, 24: Program memory, 25: Working memory, 29: Drive circuit, 30: Sensor, 33: DIP switch.

Claims (3)

(57) [Claims] An ink jet recording apparatus for recording an image on a recording medium by ejecting recording droplets of a plurality of colors based on image information, wherein the image is recorded in a predetermined area along a color boundary defined by a color difference in the image. An ink jet recording apparatus, comprising: recording control means for performing a process of setting corresponding image information to information that does not discharge the recording liquid droplets. 2. An ink jet recording apparatus according to claim 1, further comprising: identification information generating means for generating identification information corresponding to a recording medium used for recording, wherein said recording control means is configured to determine that said identification information is a predetermined information. An ink jet recording apparatus for performing the above-mentioned processing. 3. The ink jet recording apparatus according to claim 2, wherein said identification information generating means generates said identification information in accordance with a recording liquid absorption capacity of a recording medium.