JP2746742B2 - 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 that performs recording by discharging ink from a discharge port onto a recording medium, and particularly to an ink jet recording apparatus that improves the density of black recording. It relates to a recording device.

[Prior Art] Conventionally, color ink jet recording in which color recording is performed by superimposing inks using four colors of yellow (hereinafter, Y), magenta (hereinafter, M), cyan (hereinafter, C), and black (hereinafter, BK). There is a device. When three colors of Y, M, and C are superimposed on each other, the color becomes black. Therefore, in principle, three colors are sufficient. However, the black by mixing the three colors becomes cloudy, so color recording is performed using black as an independent ink. It is common to configure the device. Further, it is needless to say that a document or the like can be recorded by using only the black (BK) ink in such a color inkjet recording apparatus.

By the way, since an ink jet recording apparatus performs recording by flying ink droplets from a discharge port onto a recording medium (generally paper), one droplet of ink becomes substantially circular on the recording medium, and characters and images are formed on the recording medium. It becomes an aggregate of circular ink droplets. Since printing is performed at a predetermined discharge frequency and a predetermined print scanning pitch, even if ink droplets are continuously discharged, a space is generated between each ink droplet on the print medium when viewed microscopically. This blank space causes a decrease in the recording density, and is not preferable particularly when recording a document with black ink. Therefore, as a means for improving the recording density, for example, it is conceivable to improve the recording density by reducing the blank by making the scanning pitch fine or repeating the same recording scan.

[Problems to be Solved by the Invention] However, any of the recording density improving means as described above has a problem that the recording speed is reduced and the characteristics of high-speed recording are impaired.

In view of the above, an object of the present invention is to provide an ink jet recording apparatus which improves the recording density, particularly the black recording density, without lowering the recording speed.

Means for Solving the Problems In order to achieve the above object, according to the present invention, a black ink ejection section capable of ejecting black ink and a color ink ejection section capable of ejecting color ink other than black are arranged in the scanning direction. An ink jet recording apparatus that performs recording while relatively scanning with respect to a recording medium in a state where the color ink is recorded on a recording medium when recording an area to be recorded in black. By discharging in the same scan as the scan for discharging the black ink so that at least a part of the black ink is discharged, a blank area between adjacent black ink discharge points on the recording medium is defined as the black ink. Control means for executing a recording mode for controlling the ejection of ink so as to cover with the ink mixed with the color ink, wherein the control means controls the black recording area on the recording medium in the recording mode. It is characterized in that the amount of color ink applied is less than the amount of black ink.

Here, the color ink may be ink of at least one of cyan and magenta.

Further, the control means can control the ejection timing such that the color ink is ejected with a shift of about 1/2 dot with respect to the ejection timing of the black ink.

Further, the recording head may include a thermal energy generator that generates thermal energy for discharging the ink.

Further, the control means may perform control such that the color ink is ejected to substantially the same place as one of the black ink ejected adjacent to the recording medium.

[Operation] In the present invention, since the black ink ejection section capable of ejecting black ink and the color ink ejection section capable of ejecting color ink other than black are arranged in the scanning direction, the black ink ejection section is arranged. Color ink can be ejected in the same scan as the scanning, and the black recording density can be improved without lowering the recording speed.

Further, according to the present invention, since the color ink is ejected in the same scan as the scan for ejecting the black ink, the color ink is applied before the black ink has yet completely penetrated the recording medium, and the color ink is applied to the recording medium adjacent to the recording medium. Thus, the space area between the places where the black ink is ejected can be covered with the ink in which the black ink and the color ink are mixed. Therefore, the blank area can be covered with a color closer to black, and a change in tint can be minimized.

Further, in the present invention, as described above, in order to cover the blank area with a color closer to black, and to cover with a mixed ink of black ink and color ink, the black ink still remains on the recording medium as described above. Since it is necessary to apply the color ink before complete penetration, when both are mixed, bleeding due to ink overflow may occur,
According to the present invention, since the amount of the color ink applied to the black recording area on the recording medium is smaller than the amount of the black ink, when both are mixed, the ink does not overflow, and a sharp image with little blur is obtained. Can be.

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

FIG. 1 shows a basic configuration of an embodiment of the present invention. In FIG. 1, reference numeral A denotes a black ink recording head that discharges black ink from a discharge port to a recording medium in an ink jet recording apparatus that performs color recording using a plurality of color inks. B
Reference numeral denotes a color ink recording head which discharges a color ink other than black from the discharge port to the recording medium. C is control means for controlling both the black ink recording head A and the color ink recording head B to drive the color ink between black dots. The color ink is, for example, at least one of cyan and magenta. Further, as an example, the control means C controls the ejection timing such that the color ink is ejected between the black dots with a shift of about 1/2 dot from the ejection timing of the black dots.
Further, the control means C may control the ejection timing such that the color ink is ejected so as to be superimposed on the black dot in accordance with the ejection timing of the black dot. Further, the control means C may perform control such that the number of color ink dots is smaller than the number of black dots.

FIG. 2 shows an example of the configuration of a so-called bubble jet type color ink jet recording apparatus having an electrothermal converter as a discharge energy generating means as a preferred embodiment of the present invention.

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

The recording head unit 90 which is a bubble jet type ink jet head is mounted on the carriage 6. The recording head unit 90 is for color image formation, is arranged in the scanning direction, and is provided corresponding to each color ink of cyan (C), magenta (M), yellow (Y), and black (BK). Recording heads 9, ie, 9
A, 9B, 9C, 9D. On a surface facing each recording medium 1 at a predetermined interval (for example, 0.8 mm), a recording unit in which a plurality of (for example, eight) ink ejection ports are arranged in one vertical line is provided.

The recording head 9 facing the recording medium 1 (recording heads 9A to 9A)
9D), a plurality of ink ejection ports are formed at a predetermined pitch in the vertical direction, and the electrothermal converter (heating resistor) of each ink ejection port is driven based on recording information ( The heating (electric heating) generates a valve (bubble) in the ink, a flying ink droplet is formed by the pressure at this time, and recording is performed while ink dots adhere to the recording medium 1 in a predetermined pattern. A circuit board (not shown) of a driving circuit (driver) for driving in this manner is provided for each recording head.
Is installed.

Further, a control unit including a control circuit (CPU) of the recording apparatus and a ROM, a RAM and the like attached to the control unit are formed on a control board 15, and the control unit includes a host device 14 such as a computer.
Command signals and data signals (recording information) from the printer, and, based on the received signals, drive voltages (heater voltages) of the electrothermal transducers to the recording heads 9A to 9D via a heat driver together with driving sources such as various motors. Apply.

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

FIG. 3 shows a configuration example of a control system of the bubble jet type ink jet recording apparatus of FIG.

In FIG. 3, a CPU 21 in the form of a microprocessor
Are connected to a host device 14 such as a computer via an interface 22, and read from the host device 14 into a data memory 23, a recording information signal, a program memory 24 in the form of a ROM, and a working memory. The recording operation is controlled based on a program or data whose processing procedure is shown in FIG.

Reference numeral 30 denotes a sheet sensor, which detects whether or not the recording medium 1 exists between the transport roller 2 and the roller 3 (FIG. 2), and transmits a detection signal to the CPU 21 via the input port 31. Is done.

Outputs from the operation keys 16A to 16D (FIG. 2) on the operation panel 160 are transmitted to the CPU 21 via the input port 32, and are output to the warning lamps such as the alarm lamp 16E and the power lamp 16F. Is supplied with a control signal via the output port 36.

Reference numeral 33 denotes a DIP provided on the bottom portion of the exterior of the device.
Switch, whose output is connected to CPU2 via input port 34.
Communicated to 1.

Also, from the power supply circuit 28, a logic drive voltage VCC (5V) for operating the control logic circuit, various motor drive voltages VM (30V), a reset voltage RESET,
A heating voltage (head voltage) VH (25 V) for heating the dot forming element (electrothermal transducer) of the above and a backup voltage VDDH for protecting the recording head 9 are output. The heating voltage VH is applied to the recording head 9 by a backup voltage.
VDDH is applied to the head control circuit 29 and the recording head 9, respectively.

Hereinafter, an operation example of the color inkjet recording apparatus according to the present embodiment will be described with reference to FIGS. here,
FIG. 4 is a flowchart showing an example of a recording processing procedure, FIG. 5 is a timing chart showing an example of a head drive pulse at the time of black mix recording described later, and FIGS. 6 and 7 respectively show recording on the recording medium 1. It is explanatory drawing which expands and shows a state.

As shown in FIG. 4, first, a recording mode is set (step S1). The setting of the recording mode is performed based on a key input from the recording mode switching key 16D or a command from the host device 14.

Thereafter, at the time of recording, it is determined whether the recording mode is the color mode (step S2). If the mode is not the color mode, that is, if the mode is the white / black mode, it is determined whether or not the mode is the normal black recording mode (step S3). When in the normal black recording mode, normal black-and-white recording using only black (BK) ink is performed as in the related art. When the mode is not the normal black recording mode, the black mix recording process according to the present invention is executed (step S4).

In this black mix recording, for example, as shown in FIG. 5, not only BK ink but also cyan (C) ink or magenta (M) ink is used. In the example of Fig. 5, BK
A drive pulse having the same waveform as in BK printing, in which the ejection timing of C ink or M ink is shifted by 1/2 dot (1/2 pulse) with respect to the ejection timing of ink, is also supplied to the C or M heads 9A and 9B. . The shift of the ejection timing at this time can be obtained by applying a software delay using, for example, a buffer memory or a counter. Accordingly, as shown in FIG. 6, the recording state at this time is such that the C or M ink droplet (indicated by a dashed line) is shifted by ド ッ ト dot from the BK ink droplet (indicated by a solid line) on the recording medium 1. Recorded sequentially. Therefore, as shown in FIG. 6, a minute blank (white background) area between each BK ink droplet is almost completely filled with the C or M ink droplet and disappears. Further, at this time, the bleeding phenomenon of the ink and the like are added, and it is considered that the blank is completely eliminated. Thereby, the recording density is improved, and a recording result of ideal recording quality, which cannot be obtained by ordinary dot recording, can be obtained. In addition, since this operation is performed by one printing scan, high-speed printing can be performed without changing the printing speed as in other normal printing modes. In addition, since the blank is relatively small compared to the size of the ink droplet, and another ink is superimposed on the BK ink, the change in the tint due to the use of the C or M ink is practically almost unnoticeable. Considering that the bluish black ink is used in fountain pens and printing, there is almost no practical problem. That is, substantially black recording can be performed.

In the examples of FIGS. 5 and 6, BK dots and C or M
The other dots are made to correspond one-to-one, but the present invention is not limited to this. For example, a ratio of cyan (or magenta): 1 for black: 2 and other colors smaller than BK dots may be printed. . This can be realized, for example, by skipping the reading of the recording data from the buffer one dot at a time when another color is printed. This case is suitable, for example, when importance is attached to the sharpness of the image, or when using plain paper in which the ink easily spreads.

Further, as shown in FIG. 7, even if the C or M ink is ejected in synchronization with the ejection timing of the BK ink, the improvement in black recording density can be obtained. This is because the inks of BK and C (or M) are injected into almost the same location as shown in FIG. 2A, and these ink droplets are mixed together as shown in FIG. This is because it spreads to the adjacent BK ink and the above-mentioned minute blank area can be eliminated. In this case, one C (or M) dot is applied to two BK dots.

The black mix recording process described above is also effective in the color mode. That is, when it is determined in step S2 of FIG. 4 that the mode is the color mode, and in the next step S5, it is determined that the normal printing is performed, the conventional normal color printing is performed. In step S6, a black mix recording process for black enhancement is performed. This black mix recording process has the same contents as the black mix recording process in step S4 described above, except that the black mix recording operation described in step S4 is performed in addition to the normal color recording operation. For example, when cyan (C) is used for a black mix, cyan dots are used not only for color image creation but also for black enhancement. This can be implemented by using a signal obtained by synthesizing a cyan signal for normal color creation and a cyan signal for black enhancement as shown in FIG. 5 as a drive signal. As described above, when the black mix recording process is performed in the color mode, the density of the black recording portion is increased, so that a black line or a black contour portion is emphasized, and a color image having a good contrast with a sharp edge is obtained. . This is also suitable for a case where a color photograph and text are mixed on the same page.

(Others) The present invention brings about an excellent effect particularly in a bubble jet type recording head and a recording apparatus proposed by Canon Inc. among ink jet recording methods. This is because according to such a method, it is possible to achieve higher density and higher definition of recording.

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 both the so-called on-demand type and the continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to a sheet or a liquid path holding a liquid (ink). Applying at least one drive signal corresponding to the recording information and providing a rapid temperature rise exceeding nucleate boiling to the electrothermal transducer, thereby causing the electrothermal transducer to generate thermal energy, thereby causing the recording head to emit heat energy. This is effective because a film in the liquid (ink) corresponding to the driving signal can be formed one by one by causing film boiling on the heat acting surface. 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. U.S. Pat. No. 44
There are drops as described in 63359 and 4435262. Further, when the conditions described in US Pat. No. 4,313,124 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, in addition to a combination configuration (a linear liquid flow path or a right-angled liquid flow path) 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, according to the present invention, recording can be reliably 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 on which a recording apparatus can record. 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 integrally formed recording head.

In addition, even with the serial type printer as in the above example, the recording head fixed to the main unit or attached to the main unit enables electrical connection with the main unit and supply of ink from the main unit. The present invention is also effective when a replaceable chip type print head or a cartridge type print head having an ink tank provided integrally with the print head itself is used.

Further, it is preferable to add recovery means for the print head, preliminary auxiliary means, and the like provided as a configuration of the printing apparatus in the present invention since the effects of the present invention can be further stabilized. If these are specifically mentioned, capping means for the recording head, cleaning means, pressurizing or suction means, preheating means using an electrothermal transducer or another heating element or a combination thereof, Performing a preliminary ejection mode in which ejection is performed separately from printing is also effective for performing stable printing.

Regarding the type or number of print heads to be mounted, for example, in addition to one provided for single color ink, a plurality of print heads are provided corresponding to a plurality of inks having different print colors and densities. May be used. That is, for example, the printing mode of the printing apparatus is not limited to a printing mode of only a mainstream color such as black, and may be any of a plurality of printing heads integrally configured or a combination of a plurality of printing heads. The present invention is extremely effective for an apparatus provided with at least one of full colors by color mixing.

In addition, in the embodiments of the present invention described above, the ink is described as a liquid. However, an ink that solidifies at or below room temperature and softens or liquefies at room temperature, or the ink itself in an inkjet method. In general, the temperature is controlled within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range. I just need. In addition, the temperature rise due to thermal energy can be positively prevented by using it as energy for changing the state of the ink from a solid state to a liquid state, or ink that solidifies in a standing state to prevent evaporation of the ink can be used. In any case, the ink is liquefied by the application of the thermal energy according to the recording signal, and the ink is liquefied, and the liquid ink is discharged. The present invention is also applicable to a case where an ink that liquefies for the first time by energy is used. The ink in such a case is disclosed in
No. -56847 or JP-A-60-71260, while being held as a liquid or solid substance in a porous sheet recess or through hole, facing the electrothermal converter. It is good also as a form. 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, 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. Or the like.

[Effects of the Invention] As described above, according to the present invention, a black ink ejection unit capable of ejecting black ink and a color ink ejection unit capable of ejecting color ink other than black are arranged in the scanning direction. Since they are arranged, the color ink can be ejected by the same scan as the scan for ejecting the black ink, and the black recording density can be improved without lowering the recording speed.

Further, according to the present invention, since the color ink is ejected in the same scan as the scan for ejecting the black ink, the color ink is applied before the black ink has yet to completely penetrate the recording medium, and A blank area between adjacent places where black ink is ejected can be covered with a mixture of black ink and color ink. Therefore, the blank area can be covered with a color closer to black, and a change in tint can be minimized.

Further, according to the present invention, as described above, in order to cover the blank area with a color closer to black and to cover with a mixed ink of black ink and color ink, the black Since it is necessary to apply the color ink before the ink has completely penetrated yet, when both are mixed, bleeding due to ink overflow may occur. Is smaller than the amount of black ink, so that when the two are mixed, the ink does not overflow and a sharp image with little bleeding can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of an embodiment of the present invention, FIG. 2 is a perspective view showing an overall configuration example of an ink jet recording apparatus according to an embodiment of the present invention, and FIG. FIG. 4 is a block diagram showing a circuit configuration of a control system of the apparatus, FIG. 4 is a flowchart showing a processing procedure of an embodiment of the present invention, FIG. 5 is a timing chart showing operation timing of an embodiment of the present invention, FIG. FIG. 7 and FIG. 7 are explanatory diagrams each showing a recording result in black mix recording of the embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Recording medium, 2, 3 ... Conveyance roller, 4 ... Sheet feed roller, 5 ... Guide shaft, 6 ... Carriage, 7 ... Carriage motor, 8 ... Wire, 9 ... Recording head, 14 …… Host device, 21 …… CPU, 24 …… Program memory, 23 …… Data memory.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Makoto Takemura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Tetsuji Kurata 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inside (72) Inventor Kazuhiko Shinoda 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Koichiro Kawaguchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. ( 56) References JP-A-60-253550 (JP, A) JP-A-63-312155 (JP, A) JP-A-61-272580 (JP, A) JP-A-60-49953 (JP, A)

Claims (5)

(57) [Claims] 1. A printing method in which a black ink discharger capable of discharging black ink and a color ink discharger capable of discharging color ink other than black are arranged in the scanning direction while scanning relatively to a printing medium. A scan for ejecting the black ink so that at least a part of the color ink overlaps the black ink on a print medium when printing an area to be printed in black. The ink is ejected by the same scanning as that described above, so that a blank area between adjacent places on the recording medium where the black ink is ejected is covered by the mixed ink of the black ink and the color ink. Control means for executing a recording mode for controlling the amount of color ink applied to the black recording area on the recording medium in the recording mode is smaller than the amount of black ink. An ink jet recording apparatus comprising: 2. An ink jet recording apparatus according to claim 1, wherein said color ink is ink of at least one of cyan and magenta. 3. The apparatus according to claim 1, wherein said control means controls the ejection timing such that the color ink is ejected with a shift of about 1/2 dot with respect to the ejection timing of the black ink. The inkjet recording apparatus according to any one of the preceding claims. 4. An ink jet recording apparatus according to claim 1, wherein said recording head has a thermal energy generator for generating thermal energy for discharging said ink. 5. The control device according to claim 1, wherein said control means controls the color ink to be ejected to substantially the same place as one of the black inks ejected adjacently on the recording medium. An inkjet recording apparatus according to any one of the above items.