JPH03218848A - Ink jet recording device - Google Patents

Abstract

PURPOSE:To allow a highlight part to record data using ink mist in an analogic gradation pattern and also perform high-speed, high-resolution recording in the text recording mode by providing a discharge device which discharges ink for recording and an atomization device which ejects ink in the form of mist under applied pressure. CONSTITUTION:Bubble jet system recording heads 1 to 4 are designed so that different- color inks are supplied to ink tubes 5 to 8 from ink tanks 9 to 12. These color inks are discharged with the help of bubbles under the drive of thermal resistors arranged in liquid flow paths. Electric atomization heads 13 to 16 receive different color inks from color ink tanks 21 to 24 through color ink tubes 17 to 20. A high voltage generated by a high voltage generation circuit 32 is positively applied to an electrode 24 by a high voltage control circuit 33. The liquid flow path to which a high voltage is applied generates an electric atomization phenomenon, resulting in the breaking-up of ink dots toward a medium for recording 105 and their resultant attachment to the medium. A highlight part performs misty ink recording in an analogic gradation pattern utilizing the electric atomization phenomenon. On the other hand, data is recorded at high speed and high resolution using an ink jet technique when the device is set in the high density or text recording mode.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an inkjet recording device.

[Prior Art] In addition to inkjet recording devices, many printers used as image output devices for characters, graphics, etc. have the form of a dot printer. This can be done by combining dots to create a character. It forms images such as figures. Among these, inkjet recording devices, especially recording devices (printers) that output high-definition graphic images, perform halftone reproduction by changing the area of format dots on the recording medium using various recording methods. It is carried out.

However, as described above, the following problems may occur in the conventional technology.

In other words, for example, in a recording device that incorporates a piezoelectric element into a recording head as an ejection energy generating element, it is possible to express gradation by performing area modulation in one dot, but there is a limit to the reduction of the dot diameter. there were. Further, with this method, there are other problems such as it is difficult to highly integrate ejection ports and the recording speed is slow.

In addition, no matter what inkjet recording method is used, once the dot diameter increases beyond a certain level, there will be good reproducibility in high density areas, but there will be good reproducibility in highlight areas (low density areas).
In this case, the graininess of the dots stands out as noise and can seriously degrade the image.

[Means to solve the problem]

Therefore, the present invention provides a discharging means for recording by discharging ink onto a recording medium, and a discharging means for recording by discharging ink onto a recording medium.
The present invention is characterized by comprising a spraying means that performs recording by applying high pressure to the ink and spraying the ink in the form of a mist.

[Function J] According to the present invention, by making it possible to perform both inkjet recording by ejection and electrospray recording, the image to be output is separated into a highlight part and a high density part, and the highlight part is heated by electricity. Analog gradation mist-like recording is performed by spraying, and when recording high-density areas or text such as characters, high-speed, high-resolution recording can be performed by an inkjet method using ink discharge.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In FIG. 1, the recording medium 105 wound into a roll is
Feeding roller 103 via conveying rollers 101 and 102
The paper is held between the paper feed rollers 103 and fed in the direction f in the figure as a sub-scanning motor 150 coupled to the feed roller 103 is driven. Guide rails 106 and 107 run across this recording medium 105.
are placed in parallel, and a recording head section 90 mounted on a carriage 108 scans left and right.

The recording medium 105 is intermittently fed by the recording width of the recording head unit 90, but when the recording medium 105 is stopped, the recording head 90 scans in the P direction and discharges ink droplets according to the image signal.

FIG. 2 is a schematic diagram showing an outline of the recording head section 500 according to this embodiment. In FIG. 2, reference numerals 1, 2, 3, and 4 are conventional bubble jet recording heads, which are provided for inks of yellow, magenta, cyan, and black colors, respectively. Then, ink tanks 9, 10 for yellow, magenta, cyan, and black are provided by ink tubes 5.6, 7.8 for each color, respectively.
, 11. Each color ink is supplied from 12 by capillary action. Furthermore, by driving the heating resistor placed in each liquid path of each head using the binary recording signal, bubbles are generated in the liquid path, and the bubble energy fills the liquid path. Each color ink is ejected from the ejection port. This recording method is described in Japanese Patent Publication No. 62-11035.
Details are described in Japanese Patent Publication No. 54-59139.

Further, in the sub-scanning direction of these bubble jet type recording heads 1 to 4, there are 13, 14, 15. Sixteen electrospray heads are arranged. electric spray head 13,
14. 15. 16 is a bubble jet head 1,
2, 3. 4, each color ink tube 17.
18, 19. By 20, yellow, magenta,
Cyan and black color ink tanks 21, 22,
23. Each color ink is supplied from 24 by capillary action.

FIG. 3 shows electric spray heads 13, 14, 15. 16
The structure of

In FIG. 3, 3l shows a cross section of the electrospray head. Similar to the bubble jet head, each liquid path is filled with ink, and the high pressure generated by the high pressure generation circuit 32 is turned on and off by the high pressure control circuit 33 according to the applied recording signal. Sometimes a positive high voltage is applied to the electrode 34.

On the other hand, a metal platen 36 for flattening the recording medium 105 is disposed at a portion of the recording head portion facing the ejection opening or the injection opening forming surface, and this platen 35 is grounded. Therefore, the liquid path to which high pressure is applied generates an electrospray phenomenon, and the ink dots split toward the recording medium 105 and become a mist of small particle size and adhere to the recording medium. Furthermore, by changing the applied high voltage, the high voltage generator 32 can change the small particle size of the dispersed dots, thereby expressing gradation on the recording medium.

As shown in FIG. 1, the electric spray heads 13 to 16 and the bubble jet heads 1 to 4 are mounted on the same carriage 108, and one main scan of the carriage 10g causes the bubble jet heads 1 to 4 to perform sub scanning. It is possible to record as many dots as the number of ejection ports (for example, several tens to two hundred or more) arranged in the same direction, and if there is a highlighted area, it can be printed over a certain area by the electric spray heads 13 to 16. It is possible to record by spreading it out. In addition, electricity
Since the purpose of the spray head is to diffuse the ink to some extent, that is, to record over a wider area than the ejection aperture on the recording medium, it is desirable that the ejection orifice pitch be longer than that of the bubble jet heads 1 to 4.

FIG. 4 is a block diagram showing an example of the configuration of the control system of this embodiment.

In FIG. 4, 41 is a control circuit (CPU) that controls the recording operation of the recording apparatus according to this example. Reference numeral 42 denotes a RAM for storing a predetermined amount of image information input from an external device to which the apparatus according to the present example is connected, in units of, for example, one page. Reference numeral 43 denotes a ROM that stores a control program for this recording control section and also stores threshold matrix patterns and the like for binarizing image information.

The image information temporarily stored in the RAM 42 is subjected to image extraction and processing by a highlight part extraction circuit 44 and an image processing circuit 45, and in the high density part, a yellow (Y) head driver 46 and a head driver 47 are used.
, a driver 48 for the cyan head, and a driver 49 for the black head output a Y (yellow) signal, M (magenta signal), C (cyan signal), and BK (black) signal, which are applied to each color head and also output a high signal. In the light section, a high voltage generation circuit 32 and a high voltage control circuit 3
3, high pressure is applied to the electric spray heads of four colors of Y, M, C, and BK, and ink is sprayed.

FIG. 5 is a flowchart showing an example of the operation procedure by the control system shown in FIG.

In step S1, first 1 from the connected external device.
Enter image information for each page. This image input is, for example, image information read by a color image scanner or the like, processed by a computer, and sent as an RGB multi-value signal. As mentioned above, the input multilevel image is stored in RAM4.
2, and the highlighted portion is extracted in step S2. When performing this extraction, for example, if the threshold value is set constant, or if RGB luminance signals are input, RG
A threshold value may be set for each B, but in order to be able to extract low gradation areas when color conversion is performed, the highlight area extraction circuit 44 can extract low gradation areas by lowering the threshold to some extent. can be extracted.

In this case, the density in the vicinity of the pixel of interest may also be referred to, and a filter may be applied so that, for example, the edge portion of a highlight is not extracted.

In step S3, the highlight portion extraction circuit 44 performs image processing such as masking, UCR, correction, etc. on the area from which highlight extraction has not been performed. Next, in step S4, the graphic image is binarized into four colors of yellow, magenta, cyan, and black using a threshold pattern stored in the ROM 43, and in step S5, heads 1 to 4 are driven by each driver. Ru.

That is, the heating resistors in each liquid path of the four bubble jet heads are energized, which causes foaming and ejection to perform recording in accordance with the signal (step S6).
.

On the other hand, the area from which the highlight portion was extracted in step S2 is subjected to image processing in step S7 in the same manner as step S3, and multi-valued information in four colors of yellow, magenta, cyan, and black is obtained in step S8. Then, in step S9, the high voltage generation circuit 50
The applied voltage, application time, etc. are controlled by the high voltage control circuit 51 according to the four-color multi-value information, and by applying this to the four electric spray heads 13 to 16, spraying is performed according to the multi-value signal ( Step S10).

Note that the timing of ejection and spraying can be managed by a clock, and the driver and high-pressure control circuit make it possible to simultaneously perform ejection and spraying in one main scan of the carriage 108.

Furthermore, since the electrospray head is a head dedicated to highlight areas, it is preferable to use ink with a lighter density than the ink of the bubble jet head.

As a result, the granularity of the spray in the highlight area becomes less noticeable, resulting in a better image. Furthermore, yellow is a color that makes graininess less noticeable when recording on a recording medium with high whiteness, so it may be omitted for yellow electrospray heads or replaced with another color. is also valid.

FIG. 6 shows another embodiment of the invention.

The recording head according to this example is formed by integrating the bubble jet head and the electrospray head of the example shown in FIG. 2, and if this head is used, a total of four heads, one for each color, are sufficient. It turns out.

In FIG. 6, a heating resistor 60 for bubble jet recording and a high voltage electrode 6l for applying high voltage are arranged in one liquid path. In addition, as shown in FIG. 3, a metal platen is grounded and arranged on the back side of the recording medium at a portion facing the head, and a high voltage generation circuit 62 and a high voltage control circuit 66 for the electrode 61 are provided. An ink tank 67 is provided.

Even in such a configuration, the operation can be performed in the same manner as the operation procedure shown in FIG. 5, but the timing of ejection and spraying is different. In other words, since ejection and spraying are performed using the same head, if only one of ejection or spraying is performed, the recording of that line is completed with one main scan of the carriage, but if both ejection and spraying are performed in the same line, When a signal is generated, the same line is scanned twice and ejection and spraying are performed separately.

In the case of the embodiment shown in Fig. 6, the ink used for ejection and spraying is supplied from the same ink tank 67 (2), so bubble jet recording can be performed with high density as in the embodiment shown in Fig. 1l. Ink, electrospray recording cannot be done with light ink. However, by using the same head, the gradation of electrospray recording can be controlled not only by high pressure, but also by the heating resistor 60.
By applying pulses that do not cause foaming, the concentration of the ink filled in the liquid path is changed, and the viscosity of the ink is changed before spraying. can be changed, and multi-gradation spray recording can be realized.

(Others) The present invention brings about excellent effects particularly in a bubble jet type recording head and recording apparatus among inkjet recording types.

According to such a method, higher recording density and higher definition can be achieved.

As for typical configurations and principles thereof, it is preferable to use the basic principles disclosed in, for example, US Pat. No. 4,723,129 and US Pat. No. 4,740,796. This method can be applied to both the so-called on-demand type and the continuous type, but especially in the case of the on-demand type, it is necessary to arrange the liquid (ink) in accordance with the sheet and liquid path that hold it. The electrothermal converter that is
Generating thermal energy in the electrothermal transducer and producing film boiling on the thermally active surface of the recording head by applying at least one drive signal that corresponds to recorded information and provides a rapid temperature rise above nucleate boiling. As a result, bubbles in the liquid (ink) can be formed in one-to-one correspondence with this drive signal, which is effective. The growth and contraction of the bubble causes liquid (ink) to be ejected through the ejection opening to form at least one droplet. It is more preferable to use this drive signal in a pulse form, since the growth and contraction of bubbles can be carried out immediately and appropriately, making it possible to eject liquid (ink) with particularly excellent responsiveness. As this pulse-shaped drive signal, those described in US Pat. No. 4,463,359 and US Pat. No. 4,345,262 are suitable. Furthermore, if the conditions described in US Pat. No. 4,313,124 concerning the invention regarding the temperature increase rate of the heat acting surface are adopted, even more excellent recording can be performed.

The configuration of the recording head includes, in addition to the combination configuration of ejection ports, liquid channels, and electrothermal converters (straight liquid flow path or right-angled liquid flow path) as disclosed in the above-mentioned specifications, a heat acting section. The present invention also includes configurations using US Pat. No. 4,558,333 and US Pat. No. 4,459,600, which disclose configurations in which the wafer is placed in a bending region. In addition, Japanese Patent Application Laid-Open No. 1989-5 discloses a configuration in which a common slit is used as a discharge part of a plurality of electrothermal converters.
No. 9-123670 and Japanese Patent Laid-Open No. 5 (1973) disclosing a configuration in which an opening for absorbing pressure waves of thermal energy corresponds to a discharge part.
The effects of the present invention are also effective even with a structure based on Publication No. 9-138461. That is, regardless of the form of the recording head, fixing can be performed reliably and efficiently.

Furthermore, 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 that can be recorded by a recording apparatus.

Such a recording head may have either a configuration in which the length is satisfied by a combination of a plurality of recording heads, or a configuration as a single recording head formed integrally. In addition, even serial type recording heads like the one above can be installed in the main body of the device, making it possible to electrically connect to the main body of the device and supply ink from the main body of the device.Replaceable chip-type recording heads Alternatively, the present invention is also effective when using a cartridge type recording head that is provided integrally with the recording head itself.

In addition, regarding the type and number of recording heads installed, for example, in addition to one type that corresponds to single-color ink, there is also a plurality of recording heads that correspond to multiple inks with different recording colors and densities. It may be something that can be done.

In addition, in addition to being used as an image output terminal for information processing equipment such as a computer, the inkjet recording apparatus of the present invention may also take the form of a copying machine combined with a league, etc., or a facsimile machine having a transmission/reception function. It may be something.

[Effects of the Invention J As explained above, according to the present invention, by enabling both inkjet recording and electrospray recording by ejection, the image to be output can be separated into highlight areas and high density areas. However, in the highlight areas, analog gradation mist-like recording is performed using electrospray, and when recording high-density areas or text such as characters, high-speed, high-resolution recording can be performed using the inkjet method using ink discharge. It became so. As a result, it is possible to experiment with a high-speed, high-resolution recording device that can reduce grainy noise in the 8-light area and can express gradations.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an inkjet recording apparatus according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing the outline of the recording head, and FIG. 3 is a specific example of the configuration of the electric jet head in the recording head section. FIG. 4 is a block diagram showing the configuration of the control system of this embodiment, FIG. 5 is a flowchart showing an example of the recording processing means, and FIG. 6 is another embodiment of the present invention. FIG. 2 is a schematic diagram showing a recording head according to the present invention. 1~4・・・Bubble jet head, 13~16
...Electric spray head, 41...CPU
, 42...RAM, 43...ROM. 45... Image processing circuit, 46-49. 64... Driver, 50. 5
2...High pressure generation circuit, 51. 63...
・High voltage control circuit. Figure l Ink tank

Claims (1)

[Scope of Claims] 1) Discharging means for recording by discharging ink onto a recording medium, and recording by applying high pressure to the ink and jetting the ink in the form of a mist onto the recording medium. An inkjet recording device comprising: a spraying means for performing the following; 2) The ejection means includes an ejection port for ejecting the ink, and an ejection energy generating element that is provided in association with the ejection port and generates energy used for ejecting the ink. The spraying means has the form of an ink spraying head, and the spraying means has the form of an ink spraying head having a spraying port for spraying the ink and a high-voltage electrode provided in association with the spraying port, and The inkjet recording apparatus according to claim 1, wherein the ejection head and the ink spray head are provided separately. 3) identification means for identifying a low-density part and a high-density part of an image to be output; and the low-density part is recorded using the ink spray head, and the high-density part and the character image are recorded. 3. The inkjet recording apparatus according to claim 2, further comprising a control means for causing the inkjet head to perform recording. 4) The inkjet recording apparatus according to claim 2, wherein the ink spray head uses ink that is lighter than that of the ink discharge head. 5) The inkjet recording apparatus according to claim 3, wherein the ejection energy generating element has the form of a heating element that generates thermal energy as the energy. 6) The ejecting means has an ejection energy generating element that generates energy used for ejecting the ink, the spraying means has a high voltage electrode for applying high voltage to the ink, and the high voltage electrode and the 2. The inkjet recording apparatus according to claim 1, further comprising a recording head in which ejection energy generating elements are arranged in association with a common ejection port. 7) The ink jet recording apparatus according to claim 6, wherein the recording head has a liquid path communicating with the ejection port, and the ejection energy generating element and the high voltage electrode are arranged in the liquid path. 8) An inkjet recording apparatus, wherein the ejection energy generating element has the form of a heating element that generates thermal energy as the energy. 9) The particle size of the droplets to be sprayed is changed by causing the heating element to generate heat to an extent that the ink is not ejected, thereby changing the viscosity of the ink filled in the liquid path. The inkjet recording apparatus according to claim 8.