JPH0825655A - Method and device for recording - Google Patents

Abstract

PURPOSE:To control the total of ink solvent amount and prevent the overflow of ink and the like by using dots of higher density for color dots other than black when pixels are formed by using black dots and dots of other colors, adjusting the number of color dots other than black and controlling the density level of pixels. CONSTITUTION:A black color forming circuit 203 for forming signals of C, M and Y respectively for cyan, magenta and yellow, from which primary colors are removed, is formed, and signals for black dots for carrying out the first color recording are provide. In the case of forming black (Bk) signals, shade selection signals SC, SM and SY for jetting thick inks for C, M and Y are output in respective selection circuits 212-214 of cyan, magenta and yellow colors Then, high density dots are used in compliance with the selection signals SC, SM and SY in a system controller, and a print head is driven so that the number of a plurality of dots is adjusted and the density level of pixels is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording method and a recording apparatus, and more particularly to a recording method and apparatus capable of recording a full color image having gradation.

[0002]

2. Description of the Related Art Conventionally, in the case of forming a dot by forming a dot, a density level (the number of dots, etc.) of each pixel is determined by using a dither method or an error diffusion method, and the dot is formed according to this level. It was commonly done. Tones can be obtained to some extent by these methods, but in order to obtain even better tones, multivalued dots (dots having different densities; for example, inks having different densities) can be used. Is being considered.

FIG. 4 (a) shows an example of recording by such a system.

For example, when the density level of each pixel is expressed by a 2 × 2 matrix pattern using one type of dark dot and one light dot, the relationship between each density level and the dark and light dot patterns is shown in FIG. ).

FIG. 4A shows a case of multicolor (full-color) recording using dark and light dots for cyan (C), magenta (M), and yellow (Y), respectively.

As described above, by using the dark and light dots for each color, it is possible to maintain good gradation even when recording a full-color image.

[0007]

By the way, when full-color recording is performed, black (Bk) dots may be used in order to save ink of each color and to ensure resolution when recording black.

That is, the following Bk signal is generated from the C, M and Y signals,

[0009]

## EQU1 ## Bk = MIN (C, M, Y) Following this Bk generation, the following UCR (undercolor removal) is performed on the C, M, Y signals.

[0010]

[Equation 2]

Here, a is a UCR coefficient, and a = 1.
When it is 0, it is 100% UCR, but generally it is several tens of percent.
Often takes the value of. Further, when the value is equal to or less than a certain value (k), Bk is generally used.

FIG. 4C shows the relationship between each density level and the dot pattern when black dots are used as described above.

That is, in the example shown in FIG. 4C, the density levels of 5 or higher (the gradation range using the dark dots) in the example using the dark and light dots shown in FIG. The case where black color is generated by removing the undercolor of the signal is shown.

However, in such a case, there may be a problem with respect to the total amount of the ink solvent that is put on the recording paper during recording. That is, as shown in FIG. 5, the amount of the solvent at each density level in which the undercolor is removed in FIG. 4C increases, which may cause a problem of ink overflow or dripping on the recording paper. It was

The present invention has been made to solve the above problems, and an object of the present invention is to suppress the total amount of ink solvent and perform good recording without ink overflow. A method and a recording device are provided.

[0016]

Therefore, according to the present invention,
In a recording method for recording by forming pixels on a recording medium by selectively using black dots and dots having different densities for respective colors, the pixels are formed by using black dots and dots of other colors. At this time, for each dot of the other color, a dot having a higher density is used, and each step of controlling the density level of the pixel by adjusting the number of the dots of the other color used for forming the pixel is performed. It is characterized by having.

In addition, in a recording apparatus for recording by forming pixels on a recording medium by selectively using black dots and dots having different densities for each of the plurality of colors, the signals of the plurality of colors are used to perform recording. A black generation circuit that generates a signal of black color removal of a signal and a signal of a black dot, and when the black generation circuit generates a signal of a black dot for the pixel, a dot having a higher density is generated for each of the plurality of colors. A selection circuit that outputs a signal indicating that the high density dots are used according to the signal output by the selection circuit, and the density level of the pixel is controlled by adjusting the number of dots of the plurality of colors. And a control means.

[0018]

According to the above construction, when a black dot is used in forming a pixel, a dot having a higher density is used for other colors forming the pixel, and
The number of dots of the other color can be reduced to obtain a predetermined density for the pixel.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing the arrangement of a color printer according to an embodiment of the present invention. The printer of this embodiment uses an ink jet system and uses an NTSC video signal as image data.

In FIG. 1, the NTSC video signal is input to the decoder 101 and converted into an RGB signal. After that, it is converted into a digital signal by the S / H circuit / A / D converter 103. That is, when the user turns on a print button (not shown), the image data converted into a digital signal by the above-mentioned circuit is transferred to the data controller 1.
It is taken into the frame memory 107 via 05.

The data taken in the frame memory 107 is processed by the process controller 117 after being subjected to the processing described later with reference to FIG.
It is sent to the head driver 113 via the / A converter. As a result, the head is driven and ink is ejected.

FIG. 2 is a block diagram showing details of the image processing unit 109 shown in FIG.

The R, G, B digital data input to the image processing unit 109 is converted by the density conversion circuit 201 into C, M, Y signals. The C, M, Y signals are input to the masking circuit 205 via the Bk generating circuit 203 for generating the minimum value as Bk and removing the undercolor of the Y, M, C signals.

Here,

[0026]

(Equation 3)

The matrix calculation of is performed to correct the asymmetric color component of the ink.

Bk ', C', obtained as described above,
The M'and Y'signals are input to the selection circuits 211 to 214, respectively.

Recording position (address) information is input to each of the selection circuits 211 to 214, and Bk signal data and corresponding C ', M', Y'are input to each of the C, M, Y selection circuits.
Signal data is respectively input, and signals S _C , S _M , and S _Y for selecting the ejection port of dark or light ink to be ejected according to the combination thereof, and ejection drive signal D of each Bk, C, M, and Y ink _Bk , D _C , D _M and D _Y are output. The recording position information can be, for example, the remainder of the carriage position divided by the dither matrix size.

That is, in the selection circuits 212 to 214,
When it is determined that the Bk ink is to be ejected, the output dark / light selection signals S _C , S _M , and S _Y become signals for selecting the dark ink ejection port.

FIG. 3A shows a dot pattern formed by the processing of the image processing unit 109 described above.

That is, as shown in FIG. 3A, Bk
The other Y, M, and C dots when dots are formed are formed using only dark ink, and when forming dots in other parts, the dots are based on how many dark ink dots correspond to light ink dots. Thin out the number of. As a result, the average C, M, and Y densities in a pixel having a 4 × 4 dot formation area are the same as those in the conventional example shown in FIG. 3, and the color reproducibility is not affected. In the state shown in FIG. 3B, the amount of the ink solvent is very large as described above, and overflow or dripping may occur.
In the example shown in FIG. 3A, it is possible to reduce the amount of ink solvent ejected in the entire pixel.

The selection circuits 211 to 2 for performing the above processing
14 can be easily realized by using table conversion such as ROM.

In the above embodiment, the present invention has been described by taking the pixel formation by the matrix pattern as an example, but it is needless to say that the present invention can be applied to the case where another pixel formation method by dots is used.

The present invention can also be applied to a thermal transfer type recording apparatus using an ink ribbon or the like, although the problem of the amount of ink solvent does not occur.

Further, the recording apparatus of the present invention is not limited to a printer, but can be widely used as an output apparatus of an information processing apparatus including a recording apparatus such as a copying machine.

(Others) The present invention is provided with a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for ejecting ink, particularly in the ink jet recording system. The present invention brings about excellent effects in a recording head and a recording apparatus of the type in which the state of ink is changed by the heat energy. This is because such a system can achieve high density recording and high definition recording.

Regarding the typical structure and principle thereof, see, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740.
What is done using the basic principles disclosed in 796 is preferred. This method is a so-called on-demand type,
It can be applied to any of the continuous type, but especially in the case of the on-demand type, it can be applied to the sheet holding the liquid (ink) or the electrothermal converter arranged corresponding to the liquid path. By applying at least one drive signal corresponding to the recording information and giving a rapid temperature rise exceeding nucleate boiling, heat energy is generated in the electrothermal converter, and film boiling is caused on the heat acting surface of the recording head. Liquid (ink) corresponding to this drive signal in a one-to-one correspondence
It is effective because bubbles can be formed inside. The liquid (ink) is ejected through the ejection opening by the growth and contraction of the bubble to form at least one droplet. It is more preferable to make this drive signal into a pulse shape because bubbles can be immediately and appropriately grown and contracted, so that liquid (ink) ejection with excellent responsiveness can be achieved. As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. If the conditions described in US Pat. No. 4,313,124 of the invention relating to the rate of temperature rise on the heat acting surface are adopted, more excellent recording can be performed.

As the constitution of the recording head, in addition to the combination constitution of the discharge port, the liquid passage, and the electrothermal converter (the straight liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned respective specifications. US Pat. No. 4,558,333, US Pat. No. 4,558,333, which discloses a configuration in which a heat acting portion is arranged in a bending region.
The structure using the specification of No. 59600 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 the 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 corresponding to the ejection portion is disclosed in JP-A-59-138461. That is, according to the present invention, recording can be surely and efficiently performed regardless of the form of the recording head.

Further, the present invention can be effectively applied to a full line type recording head having a length corresponding to the maximum width of a recording medium which can be recorded by the recording apparatus. Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads or a configuration as one recording head integrally formed.

In addition, even in the case of the serial type as in the above example, the recording head fixed to the main body of the apparatus or the electrical connection to the main body of the apparatus and the ink from the main body of the apparatus by being attached to the main body of the apparatus. The present invention is also effective when a replaceable chip-type recording head that can be supplied or a cartridge-type recording head in which an ink tank is integrally provided in the recording head itself is used.

Further, as the constitution of the recording apparatus of the present invention, it is preferable to add an ejection recovery means of the recording head, a preliminary auxiliary means and the like because the effect of the present invention can be further stabilized. Specifically, heating is performed by using a capping unit, a cleaning unit, a pressure or suction unit for the recording head, an electrothermal converter or a heating element other than this, or a combination thereof. Examples thereof include a preliminary heating unit for performing the discharge and a preliminary discharge unit for performing discharge different from the recording.

Regarding the type and number of recording heads to be mounted, for example, only one is provided corresponding to a single color ink, or a plurality of inks having different recording colors and densities are supported. A plurality of pieces may be provided. That is, for example, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but it may be either the recording head is integrally formed or a plurality of combinations may be used. The present invention is also extremely effective for an apparatus provided with at least one of full-color recording modes by color mixing.

In addition, in the above-described embodiments of the present invention, the ink is described as a liquid, but an ink that solidifies at room temperature or lower and that softens or liquefies at room temperature may be used. Or, in the inkjet system, it is common to control the temperature of the ink itself within the range of 30 ° C. or higher and 70 ° C. or lower to control the temperature so that the viscosity of the ink is within the stable ejection range. Sometimes, a liquid ink may be used. In addition, the temperature rise due to thermal energy is positively prevented by using it as the energy of the state change from the solid state of the ink to the liquid state, or in order to prevent the evaporation of the ink, it is solidified and heated in the standing state. You may use the ink liquefied by. In any case, by applying heat energy such as ink that is liquefied by applying heat energy according to the recording signal and liquid ink is ejected or that begins to solidify when it reaches the recording medium. The present invention can be applied to the case where an ink having a property of being liquefied for the first time is used. In this case, the ink is
JP-A-54-56847 or JP-A-60-7
As described in Japanese Patent No. 1260, it may be configured to face the electrothermal converter in a state of being held as a liquid or a solid in the concave portion or the through hole of the porous sheet. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

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

[0046]

As is apparent from the above description, according to the present invention, when a black dot is used in the pixel formation, a dot having a higher density is used for other colors forming the pixel. , The number of dots of the other color can be reduced to obtain a predetermined density for the pixel.

As a result, when each dot is formed by the ink ejected on the recording medium, the amount of the ink solvent ejected can be suppressed and good recording can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration for data processing of a printer according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an image processing unit shown in FIG.

3A is a schematic diagram showing pixel formation according to an embodiment of the present invention, and FIG. 3B is a schematic diagram showing a comparative example thereof.

4A, 4B and 4C are schematic views showing pixel formation according to a conventional example.

FIG. 5 is a diagram showing, for each density level, the amount of ink solvent that is ejected to the pixel in forming the pixel of the conventional example.

[Explanation of symbols]

 100 System Controller 101 Decoder 103 S / H Circuit / A / D Converter 105 Data Controller 107 Frame Memory 109 Image Processing Unit 111 D / A Converter 113 Head Driver 115 Head 117 Process Controller 119 Memory Controller 201 Density Conversion Circuit 203 Bk Generation Circuit 205 Masking circuit 211 Black selection circuit 212 Cyan selection circuit 213 Magenta selection circuit 214 Yellow selection circuit

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Claims (4)

[Claims] 1. A recording method for recording by forming pixels on a recording medium by selectively using black dots and dots having different densities for each of a plurality of colors, wherein the pixels are black dots and other colors. When the dots are formed by using the dots of the other color, the dots of higher density are used, and the density level of the pixel is adjusted by adjusting the number of the dots of the other color used for forming the pixel. A recording method comprising controlling each step. 2. A recording apparatus for performing recording by forming pixels on a recording medium by selectively using black dots and dots having different densities for each of the plurality of colors, and A black generation circuit that generates a signal of black color removal of a signal and a signal of a black dot; and when the black generation circuit generates a signal of a black dot for the pixel, a dot having a higher density for each of the plurality of colors is generated. A selection circuit that outputs a signal indicating that it is used, and the high-density dots are used according to the signal output by the selection circuit, and the density level of the pixel is controlled by adjusting the number of dots of the plurality of colors. A recording device, comprising: a control unit. 3. The recording apparatus according to claim 2, wherein the black dots and the dots having different densities of the plurality of colors are formed by ink ejected from different ejection ports of an inkjet head. 4. The recording apparatus according to claim 3, wherein the ink jet head uses the thermal energy to generate bubbles in the ink and ejects the ink as the bubbles are generated.