JPH08238762A - Ink jet recorder - Google Patents

Abstract

PURPOSE: To provide an ink jet recorder which can form an image of high quality level without black streak and in which the time required to form the image is short. CONSTITUTION: Nozzles formed in a recording head are divided into groups X, Y, Z, the image thinned off in a main scanning direction P is formed by the nozzles Z-1 to Z-4 of the Z group, the image interpolated from the thinned- off image is formed by the nozzles X-1 to X-4 of the X group, and the image of no thinning off is formed by the nozzles Y-1 to Y-4 of the Y group, and the intermittent feeding of a recording sheet 4 is set to 'e'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called scanning type ink jet recording apparatus for recording while scanning a recording head.

[0002]

2. Description of the Related Art Conventionally, as an image recording apparatus, an ink jet recording apparatus which prints (records) by ejecting ink onto a recording material is known.

The ink jet recording apparatus is a non-impact type recording apparatus and has features such as low noise and easy color image recording by using multicolor inks. It is becoming popular.

FIG. 12 is a schematic perspective view of an ink jet recording apparatus according to a conventional example.

In FIG. 12, a recording material 45 wound in a roll shape passes through conveying rollers 41 and 42 and a feeding roller 4
The sheet is nipped by the sheet No. 3 and is fed in the direction of an arrow 44 in the figure in accordance with the driving of the sub-scanning motor 52 coupled to the feeding roller 43. Guide rails 46 and 47 are installed in parallel across the recording material 45, and a recording head 49 mounted on a carriage 48 scans left and right. The carriage 48 is equipped with heads 49Y, 49M, 49C, and 49Bk for ejecting four color inks of yellow, magenta, cyan, and black, each of which has a plurality of ink ejection ports arranged in parallel, and corresponding to this head, 4 Colored ink tanks are arranged.
The recording material 45 is intermittently fed by the recording width by one scan of the recording head 49, and when the recording material 45 is stopped, the recording head 49 scans in the P direction to produce a binarized image signal. A corresponding ink droplet is ejected.

In such an ink jet recording apparatus, the characteristics of the recording material 45 are important, and in particular, the ink bleeding characteristics on the recording material 45 have a great influence on the image quality.

The "bleeding rate" is known as an index showing the ink bleeding characteristic of the recording material. This shows how the diameter of the ink droplets ejected from the inkjet nozzle spreads several times on the recording material. Bleed rate = (dot diameter on recording material) / (ejected ink droplet diameter) ) Is given by. For example, the ink droplet diameter during flight is 30 μm
If a dot of 90 μm is formed on the recording material, the bleeding rate of the recording material is 3.0.

With a recording material having a low bleeding rate, the image density becomes low, and it becomes difficult to obtain a high-quality image with a texture, and black streaks may occur on the recorded image.

In order to solve such a problem, it is effective to use the multi-scan method, and it becomes possible to eliminate black stripes. The characteristics of this multi-scan method will be described with reference to FIG. Generally, in the multi-scan method, the head is divided into three blocks of X, Y, and Z and controlled. In this example, 4 for each of the X, Y, and Z blocks.
Nozzles X-1 to X-4, Y-1 to Y-4, Z-
1 to Z-4.

In the first scan of the head, the nozzles of the Z block print on the portion Z'on the recording sheet 40 by thinning it to 1/3 in the scanning direction. Subsequently, the recording sheet 40 is sub-scanned in the B direction by the length d, thinned to 1/3 in the scanning direction by the nozzles of the Y block of the head, and thinned to the Y'position at the Z'position. Record the drawn dots. Further, the recording sheet 40 has a length of B
At the position X ', the nozzles of the X block of the head print the dots thinned out at the positions Y'and Z'. In this way, since printing is performed so that dots printed by the same nozzle are not continuous in the P direction, image disturbance and the like caused by fluctuations of ink droplets during ink ejection are less noticeable.

[0011]

However, in the above-described conventional example, since the multi-scan method is applied to all the nozzles, the time required to form an image becomes longer than that in the normal serial scan. Further, the effect cannot be sufficiently obtained by simply performing the multi-scan evenly on the edge of the image.

An object of the present invention is to provide an ink jet recording apparatus capable of forming a high-quality image without black streaks and the like, which requires a short time to form the image.

[0013]

SUMMARY OF THE INVENTION An ink jet recording apparatus of the present invention comprises a recording head which is movable in the main scanning direction and is capable of ejecting ink from a plurality of nozzles, and the recording head and a recording medium are arranged in the sub scanning direction. In an ink jet recording apparatus having a moving means for relatively moving, with respect to a plurality of recording positions of an image recorded for each scanning of the recording head, one recording portion on one side in the sub-scanning direction and the other direction in the sub-scanning direction. A means for controlling the recording head and the moving means, and an image recorded for each scanning of the recording head, so that the side recording portions overlap each other and their central portions in the sub-scanning direction do not overlap each other. With respect to the above, a means for thinning out print pixels on one side in the sub-scanning direction and interpolating print pixels on the other side in the sub-scanning direction in accordance with the thinned-out amount are provided.

[0014]

The ink jet recording apparatus of the present invention can form a high-quality image without black stripes by partially performing multi-scan, and shorten the time required for image formation.

[0015]

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

(First Embodiment) FIG. 1 is a schematic diagram showing a main part and a control system of a color ink jet recording apparatus as a first embodiment of the present invention. In FIG. 1, the recording sheet 40
Passes through the transport rollers 41, 42, and then the feeding roller 4
By the rotation of 3, 43, it is sent in the direction of arrow 44.

A guide shaft 46 is installed in parallel across the portion 45 of the recording sheet 40, and a carriage 48 is provided.
The recording head 49 composed of a plurality of (four) heads mounted on the recording medium is reciprocated in the left and right main scanning directions to perform recording scanning. The recording head 49 on the carriage 48 is composed of a cyan head 49C for ejecting ink color cyan, a magenta magenta head 49M, a yellow yellow head 49Y, and a black black head 49Bk.
An ink tank for the corresponding ink is connected to each head. The recording sheet 45 is intermittently fed in the sub-scanning direction,
While it is stopped, the recording head 49 (carriage 48) ejects ink droplets from the nozzles in accordance with the image signal while scanning in the direction of arrow P. The carriage 48 is
A carriage motor (pulse motor) 51 reciprocates through a timing belt 47, and the feeding roller (sheet feeding roller) 43 is rotationally driven by a sheet feeding motor 52.

The control circuit 53 for controlling the recording operation outputs a reader control signal 55 to the reader section (or computer) 54. The reader unit 54 sends an image reading signal to the image processing circuit 56. The image processing circuit 56
The image data sent from the printer is sent to the carriage motor driver 58 and the nozzle control circuit 70 via the control circuit 53, and the image signal is sent to the recording head 49.

FIG. 2 is a schematic view of the order of use of the nozzles in this embodiment, and the recording head 49 (heads 49C, 49M,
The nozzles (49Y, 49Bk) are used by being divided into X, Y, and Z groups, respectively. In FIG. 2, it is assumed that 12 nozzles are formed in one head.

In the X block, 1 in the Z block of the previous scan
The dots thinned to 1/2 are recorded so as to interpolate the dots thinned to / 2. In the Y block, the multi-scan method is not performed, and the image data is recorded as it is without thinning out dots. In the Z block, the dots thinned to 1/2 are recorded. When the recording for one line is completed in this way, the sheet feeding motor 52 is driven to feed the recording sheet 45 in the direction of arrow B by the length e. An image is formed by repeating this. The number of nozzles in the X and Z blocks that perform multi-scan may be equal, and the number of those nozzles is not limited.

FIG. 3 shows the scanning of the head when forming one image. The arrow P indicates the main scanning direction of the recording head 49, and the arrow B indicates the feeding direction (sub-scanning direction) of the recording sheet 40. In the recording line at the position of the mark ◯ in FIG. 32, that is, the first line at the beginning on the recording sheet 40, the dot interpolation by the X block as shown in the nozzle use order of FIG. , Y blocks are recorded as they are as image data. Similarly, in the recording line at the position of ● in the figure, that is, in the last line on the recording sheet 40,
Dot thinning by the Z block is not performed, and the Z block prints the image data as it is, like the Y block.

FIG. 4 is a block diagram of the nozzle control circuit 70 of this embodiment.

Image signal 1 sent from the control circuit 53
No. 06 is distributed by the nozzle selection circuit 105 into image signals 107 and 109 of nozzles that perform multi-scan and image signals 108 of nozzles that do not. The image signal 106 of the nozzle that does not perform multi-scan is sent to the head,
The image signal 107 of the nozzle of the Z block that performs the multi-scan is output to the AND circuit 104, and the image signal 109 of the nozzle of the X block that performs the multi-scan is output to the NAND circuit 102. Reference numeral 71 is a pattern generation unit 71 that generates data for thinning out an image signal and interpolation, and has a filter table 101 as described later.

FIG. 5 is one of model diagrams of the filter table 101. This table 101 produces the effect of a filter having a dot arrangement that does not generate black stripes. The pattern 81 shown in the drawing forms a pattern of data of "0", "0", "0", "1" from the top to the bottom, and the data is sequentially read from above and the circuit 102, It is output to 104. An image signal 107 synchronized with the clock signal is also sequentially output to the AND circuit 102, and is output as an image signal corresponding to the nozzle of the Z block via the AND circuit 104. Then, each time the head moves in the scanning direction by one pixel, data is sequentially read from the pattern 81, and the data is "0".
When, the image signal is not output from the AND circuit 104, and the nozzles of the Z block do not eject ink. on the other hand,
When the data is "1", an image signal is output from the AND circuit 104, and the nozzles of the Z block corresponding thereto eject ink to perform recording. Therefore, the pattern 81
In the scanning direction of the head by using
The image formed by the nozzles of the block is drawn for three pixels and then recorded at the fourth pixel, which is repeated.

On the other hand, the signal read from the pattern 81 is input to the NAND circuit 102 together with the image signal 109 corresponding to the nozzle of the X block, so that the nozzle of the X block is formed in the head scanning direction. The image is recorded for three pixels and then thinned out at the fourth pixel. That is, the dots thinned by the nozzles of the Z block are interpolated.

Furthermore, by providing a plurality of such filters, it is possible to obtain a more complicated dot thinning pattern, and it is possible to create an optimum thinning pattern that eliminates black streaks on a recorded image.

When the recording density changes due to the difference in the image data, white stripes or black stripes may not appear on the recorded image and the effect of multi-scan may not be obtained. For example, when image data with high recording density is input and multi-scan is performed using the same filter table 101 as when image data with low density is input, the effect is sufficiently obtained. Sometimes there is not.

Therefore, in this embodiment, in order to manually switch the filter table 101 for thinning according to the image data or the density of the original to be copied, according to the signal sent from the manual switching circuit 200 of FIG. The selector circuit 103 switches the filter table 101.
This makes it possible to obtain a high-quality image without streaks. In this case, as the filter table 101 to be switched according to the document density, for example, as shown in FIG. 6, it is possible to select a filter table which gradually increases the thinning range as the image density increases. Note that FIG. 6 is an example of a case where dots are thinned out in the nozzle arrangement direction (nozzle row direction) as in the second embodiment described later.

(Second Embodiment) In the present embodiment, dots are thinned out in the nozzle direction of the head, whereas the first embodiment described above thins out dots in the scanning direction of the head.

In this embodiment, for example, as the filter table 101, the pattern 81 shown in FIG. 5 is used as in the first embodiment described above, and the data of the pattern 81 is sequentially read from the top to obtain the pattern shown in FIG. Circuit 104,1
Enter in 02. Then, the image signals 10 of the nozzles Z-1, Z-2, Z-3, and Z-4 of the Z block shown in FIG.
If 7 is entered, the corresponding table 1
The data of “0”, “0”, “0”, “1” is read from 01. Therefore, when the image signal of the Z-1 nozzle Z-1 is sent from the nozzle selection circuit 105, the data of "0" is sent from the filter table 101 to the AND circuit 104, and the image signal of the Z-1 nozzle is sent. Is "0", and printing is not performed by the Z-1 nozzle. The same applies to the Z-2 and Z-3 nozzles. The image signal of the Z-4 nozzle is the nozzle selection circuit 10 described above.
5 is sent from the filter table 101, the data “1” is sent to the AND circuit 104, and Z-
The four nozzles perform recording according to the image signal. As described above, since the AND circuit 104 is used, the first three pixels are thinned out in the nozzle array direction, and recording is performed at the fourth pixel.

Furthermore, such a filter table 10
By providing a plurality of 1's, a more complicated dot arrangement becomes possible and an optimum thinning pattern that eliminates black streaks on a recorded image can be created. Further, for the nozzle of the X block to be interpolated, the filter table 101 used for thinning out the image data of the nozzle of the Z block is used, and the data read from the table 101 and the image of the nozzle of the X block are used. Signal 109 and NA
By inputting to the ND circuit 102, an interpolated image signal can be easily obtained.

(Third Embodiment) In the present embodiment, by using the filter table 101 and a means for detecting the density from the image data at the same time, the filter table 101 is changed in accordance with the image data to obtain a high quality image. Get the image quality of.

FIG. 7 is a schematic diagram of a color ink jet recording apparatus and its control system as the present embodiment.

In FIG. 7, the image data for one scan sent from the host computer or the reader unit 54 is once stored in the buffer memory 30. Then, the image processing circuit 56 calculates the recording density from the image data corresponding to the nozzles near the end of the head, and the signal 201 based on the calculation result is sent to the nozzle control circuit 70. Then, the filter table 101 in the nozzle control circuit 70 is selected.

FIG. 8 is a block diagram of the nozzle control circuit 70 of this embodiment. The signal 201 sent from the image processing circuit 56 is sent to the selector 103, whereby the selector 103 selects a filter to be used from the filter table 101, and the signal from the selected filter is AND circuit 104, NAND circuit 102. Sent to.
As a result, even if the density of the image data changes, the optimum filter can always be selected in real time to obtain a higher quality image.

(Fourth Embodiment) In this embodiment, in addition to the multi-scanning means in the third embodiment described above, dots formed in the matrix are thinned out at random to obtain a higher quality image. To get

FIG. 9 is a schematic view showing a color ink jet recording apparatus and its control system as the present embodiment.

In FIG. 9, the image data for one scan sent from the host computer or the reader unit 54 is once stored in the buffer memory 30. Then, the recording density is calculated by the image processing circuit 56 from the image data corresponding to the nozzles near the end of the recording head 49,
Based on the calculation result, the matrix generation circuit 31 forms a matrix described later, and the contents are output as a signal 202. Further, the circuit 31 simultaneously generates a random number and sends it to the nozzle control circuit 70 together with the signal 202.

FIG. 10 is a block diagram of the nozzle control circuit 70. The signal 202 sent from the matrix generation circuit 31 enters the filter table 101, and the matrix corresponding to the signal 202 and the filter table 10 are input.
The filter of No. 1 is synthesized as described later, and the result is output to the selector 103. The selector 103 switches the filter according to the image density data by the signal 201 sent from the image processing circuit 56.

Regarding the matrix, for example, FIG.
As in (a), in the method of thinning out in the nozzle row direction in order to perform multi-scan for two nozzles at the end of the head,
Form a matrix of 2 × 2 (dots). In addition, FIG.
As in (b), in the method of thinning out in the nozzle row direction in order to perform multi-scan for four nozzles at the end of the head,
Two 2 × 2 (dot) matrices are arranged in the nozzle row direction of the head. Further, as shown in FIG. 11C, in the method of thinning out in the nozzle row direction in order to perform multi-scanning for 6 nozzles at the end of the head, a matrix of 2 × 2 (dots) is arranged in the nozzle row direction of the head. Line up three. As described above, the number of matrices for 2 × 2 (dots) is increased by the recording density near the head end portion calculated based on the image data, and at the same time, the dots in the matrix are thinned out at random. Controls the number of dots that are finally printed.

In the present embodiment, even when image data such as CG data having a density higher than that of a normal image is sent, a high-quality image that is more effective by multi-scan can be obtained.

(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 linear liquid passage or the right-angled liquid passage) as disclosed in the above-mentioned 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.

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 or the ink from the main body of the apparatus by being mounted on 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 the ejection recovery means of the recording head, the preliminary auxiliary means and the like because the effects 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, besides the one 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, and a facsimile apparatus having a transmission / reception function. It may be a form or the like.

[0050]

As described above, since the ink jet recording apparatus of the present invention is configured to partially perform multi-scan, it is possible to form a high-quality image without black stripes, The time required for formation can also be shortened.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a main part of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a usage order of nozzles in the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a scanning direction of a recording head in the first embodiment of the invention.

FIG. 4 is a block configuration diagram of a nozzle control circuit shown in FIG.

5 is an explanatory diagram of a filter table shown in FIG.

FIG. 6 is an explanatory diagram of a thinning pattern according to image density.

FIG. 7 is a schematic diagram of a main part of a third embodiment of the present invention.

8 is a block diagram of the nozzle control circuit shown in FIG.

FIG. 9 is a schematic diagram of a main part of a fourth embodiment of the present invention.

10 is a block diagram of the nozzle control circuit shown in FIG.

FIG. 11 is an explanatory diagram of a thinning pattern according to a fourth embodiment of the present invention.

FIG. 12 is a schematic view of a main part of a conventional example.

FIG. 13 is an explanatory diagram of a usage order of nozzles in a conventional example.

[Explanation of symbols]

 30 buffer memory 31 matrix generation circuit 49 recording head 70 nozzle control circuit 101 filter table 102 NAND circuit 103 selector 104 AND circuit 105 nozzle selection circuit 111 filter generation circuit

Claims (5)

[Claims] 1. An ink jet recording apparatus comprising a recording head which is movable in a main scanning direction and which can eject ink from a plurality of nozzles, and a moving means which relatively moves the recording head and a recording medium in a sub scanning direction. In regard to a plurality of recording positions of an image recorded for each scan of the recording head, one recording portion on one side in the sub-scanning direction and a recording portion on the other side in the sub-scanning direction overlap each other, and A unit that controls the recording head and the moving unit so that the central portions in the scanning direction do not overlap each other, and a recording pixel on one side in the sub-scanning direction with respect to an image recorded for each scanning of the recording head. An ink jet recording apparatus, comprising: thinning-out and means for interpolating a recording pixel on the other side in the sub-scanning direction according to the thinning-out. 2. The ink jet recording apparatus according to claim 1, further comprising selection means for selecting a pattern of thinning and interpolation of the recording pixels. 3. The ink jet recording apparatus according to claim 2, wherein the selection unit selects the pattern according to an image density obtained from image data. 4. The ink jet recording apparatus according to claim 2, wherein the selection unit changes the pattern with a random number. 5. The recording head has an electrothermal conversion element for generating heat energy that causes film boiling in the ink as energy used for ejecting the ink. 4. The inkjet recording device according to any one of 4.