JPH10329311A - Apparatus and method for ink-jet recording - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high-density images even to a paper of a small ink reception capacity, by providing a means which prints images on both faces of the paper as recording faces. SOLUTION: When a paper 20 is transferred in a sub scan direction while a recording head (carriage 5) is moved and scanned in a main scan direction, ink drops of required colors are discharged from nozzles of a color recording head 6, whereby a color image (including a black image) is recorded on the paper 2. At this time, when the image is to be printed to both faces of an OHP paper as recording faces, data are processed to be printed to a front face of the OHP paper P, and at the same time printed to a rear face of the OHP paper P. Since the image is printed to both faces of the OHP paper in this manner, the image can be seen as has an equal density to when two OHP papers showing the same image are overlapped. Therefore, the image close to a required density can be obtained even when a density of the image of each face is lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus and an ink jet recording method, and more particularly, to an ink jet recording apparatus and an ink jet recording method capable of recording an image on a transparent sheet such as an overhead projector sheet.

[0002]

2. Description of the Related Art In general, an overhead projector (hereinafter, referred to as "OHP") is used as an auxiliary means for explaining to a large number of audiences at once such as a conference or a performance.
However, color ink jet printers are particularly used for recording images on OHP paper.

[0003] This is because, in an ink jet printer, a water-based ink is used as a coloring material, so that a clear image with a higher transparency can be obtained than a copying machine using a toner. This is because even a business document that uses a lot of characters and ruled lines to record it in an embedded manner has sharp edges and a sharp image can be obtained. Further, cost performance may be reduced as compared with a case where an originally expensive OHP sheet and a supply expensive copying machine or sublimation type printer are combined.

However, an ink jet printer uses a liquid ink to land it on a sheet (recording medium) to perform recording. Therefore, the fixing of ink droplets on the sheet requires evaporation of moisture into the air and paper. This is done by infiltration.
If the evaporation of the water and the permeation of the ink are not carried out smoothly, the ink spreads on the paper surface and causes bleeding, so that a highly permeable ink is used.

[0005] However, most of OHP paper is a resin film, and is coated only with an ink receiving layer of several μm to several tens of μm. Bleeding such as fusion occurs. That is, when the ink droplets I1 and I2 of different colors are sequentially landed on the OHP paper P as shown in FIG. 12, the ink droplets do not penetrate into the OHP paper P, so that the dots D1 and I2 formed by the ink droplets I1 and I2 of each color. D2 fuses to significantly reduce the printing quality. In particular, when the black ink is made to have different physical properties from those of the other color inks in order to make the printing of monochrome text sharper,
Dot fusion is more likely to occur and severe bleeding occurs.

[0006] Even if dots of the same color are applied, if a large amount of ink is applied like a solid portion, the dots are recognized as color unevenness as shown in FIG. When such color bleeding or color unevenness occurs, even if the reflection type projector can make a certain degree of mischief, the transmission type projector will emphasize it in the opposite direction, resulting in a serious deterioration in image quality.

For this reason, when printing on OHP paper, the amount of ink is limited and the image quality is different but only an image with a low density can be obtained. In order to avoid the decrease in the image density, there are a method of increasing the concentration of the dye or the pigment in the ink and a method of relaxing the limitation of the amount of ink that can be ejected.

In this case, if the concentration of the dye or pigment in the ink is increased, a limitation is imposed on the OHP paper so that the ink can be stably ejected for a long time before the limitation on the OHP paper.
If the density is increased beyond this limit, the ejection of the ink becomes unstable, or the ink sticks to the nozzle orifices and clogging easily occurs. Also, if the density is adjusted to OHP paper, the density will be too high when printed on plain paper,
Since good image quality cannot be obtained, in order to avoid this, an ink or head dedicated to OHP paper is further mounted,
Correction means, such as changing the amount of ink, must be taken, which increases costs.

Therefore, conventionally, a method of relaxing the ink amount restriction has been taken, and as described in, for example, JP-A-60-48366 and JP-B-4-48626, sufficient time has been taken. The density is increased by dot overprinting, and as described in Japanese Patent Application Laid-Open No. 3-142252, thinning is performed around the dots to be printed so that the dots do not overlap each other.

For example, FIG. 14A shows an example in which dots that are physically overlapped are simply thinned out. In this case, in order to compensate for a substantial decrease in the density, the density of the pigment or dye is increased to increase the density of the ink. Is set higher than usual.
FIG. 2B shows an example in which the original density is maintained by complementing the dots thinned out in FIG. 2A and by repeatedly hitting them. Usually, a thinning pattern is shot once and then a carriage return is performed. Again to input a complementary pattern, or input a complementary pattern at the time of carriage return (return). FIG. 3C shows the same dot pattern as 2
This is an example in which the shortage of density is compensated by beating.

[0011]

However, it takes a considerable amount of time to increase the density by overprinting dots, and to perform overprinting within a practical time, it is necessary to overprint before the ink is sufficiently dried. , Resulting in an overflow of the ink.
In addition, when dots are thinned out, the sharpness is reduced by the enlarged projection, so that the present invention can be applied only to the case where resolution is not required. further,
Even if the thinning of these dots, the implantation of the complementary pattern, or the double-strike are performed, the color unevenness and bleeding are not improved so much. When the printing of the thinned pattern is stopped, the color unevenness becomes conspicuous.

The present invention has been made in view of the above points, and has as its object to provide an ink jet recording apparatus and an ink jet recording method capable of obtaining a high-density image even on paper having a small ink receiving amount.

[0013]

In order to solve the above-mentioned problems, the ink jet recording apparatus according to the first aspect of the present invention is configured to include means for printing an image with both sides of a sheet as recording surfaces.

According to a second aspect of the present invention, in the inkjet recording apparatus of the first aspect, when using inks having different physical properties, an image is printed on different recording surfaces of the paper with the inks having different physical properties. Was provided.

According to a third aspect of the present invention, there is provided the ink jet recording apparatus according to the first or second aspect, wherein
The image forming apparatus includes means for printing each image obtained by performing different image processing on the same printing data on both sides of the sheet.

According to a fourth aspect of the present invention, there is provided the ink jet recording apparatus according to any one of the first to third aspects, wherein an image to be printed on one surface of the sheet and an image to be a left and right mirror image are printed on the other surface. It was configured to have a means for copying.

According to a fifth aspect of the present invention, there is provided the ink jet recording apparatus according to any one of the first to fourth aspects, wherein a thinning pattern for complementing the thinning dots of the image printed on one surface of the sheet by the thinning pattern is provided. A configuration is provided in which means for printing an image is provided on the other surface.

According to a sixth aspect of the present invention, there is provided the ink jet recording apparatus according to any one of the first to fifth aspects, wherein when both sides of the sheet are designated as the recording side, the both sides are designated as the recording side. It is configured to have a means for performing copying.

According to a seventh aspect of the present invention, there is provided the ink jet recording apparatus according to any one of the first to sixth aspects, wherein printing heads are provided on both sides of the sheet conveying path.

According to an eighth aspect of the present invention, in the ink jet recording apparatus for recording an image by ejecting ink droplets onto a sheet, the image is printed with both sides of the sheet as recording surfaces.

According to a ninth aspect of the present invention, in the ink jet recording method of the eighth aspect, when inks having different physical properties are used, the inks having different physical properties print an image on different recording surfaces of the paper. And

According to a tenth aspect of the present invention, there is provided an ink jet recording method comprising:
In the ink-jet recording method according to claim 8 or 9, each image obtained by performing different image processing on the same print data on both sides of the paper is printed.

[0023] The ink jet recording method according to claim 11 is characterized in that:
11. The ink jet recording method according to any one of claims 8 to 10, wherein after printing an image on one surface of the paper, the printed image and an image serving as a left and right mirror image are printed on the other surface of the paper. Configuration.

According to a twelfth aspect of the present invention, there is provided an ink jet recording method comprising:
The ink jet recording method according to any one of claims 8 to 11, wherein an image is printed on one surface of the paper in a thinning pattern, and then the thinned dots are printed on the other surface of the paper in the thinning pattern. Is configured to print an image with a thinning pattern that complements.

The ink jet recording method of claim 13 is
The ink jet recording method according to any one of claims 8 to 12, wherein printing is performed with both sides of the sheet as recording surfaces only when designation is made of both sides as recording surfaces.

The ink jet recording method of claim 14 is:
In the ink jet recording method according to any one of claims 8 to 13, an image is simultaneously recorded on both sides of the sheet.

[0027] The ink jet recording method of claim 15 is as follows:
In the ink jet recording method according to any one of claims 8 to 14, the paper is a paper for an overhead projector.

[0028]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram of an ink jet recording apparatus according to the present invention. In this ink jet recording apparatus, a carriage 5 is slidable in a main scanning direction (a direction indicated by an arrow A in FIG. 2) by a guide rod 3 and a guide plate 4 which are laid between left and right side plates 1 and 2 (see FIG. 2). And a recording head 6 composed of an ink-jet head is mounted on the lower surface side of the carriage 5 with the ink droplet ejection direction facing downward, and an ink of each color is supplied to the recording head 6 on the upper surface side of the carriage 5. An ink tank (ink cartridge) 7 is mounted.

As shown in FIG. 3, the recording head 6 includes a head 6y for discharging yellow (Y) ink, a head 6m for discharging magenta (M) ink, and a head 6c for discharging cyan (C) ink. And a head 6b for discharging black (Bk) ink in the main scanning direction. Each of the heads 6y, 6m, 6c, 6b has a number of recording nozzles 8 arranged in two rows in the sub-scanning direction. Then, as described later, each of the heads 6y, 6m, 6c, 6b
Is divided into n nozzle groups, in this case, the recording nozzles 8 in one of the two rows are defined as a nozzle group Na, and the recording nozzles 8 in the other row are divided into a nozzle group Nb. Drive control.

Here, each head 6y, 6m, 6c, 6b
As shown in FIG. 4, a nozzle forming member 12 having a plurality of recording nozzles 8 formed on a front surface of a liquid chamber forming member 11 forming a liquid chamber 10 is provided. By applying pressure to the ink in the liquid chamber 10 by the energy generating means, the ink in the liquid chamber 10 is supplied from the recording nozzle 8 of the nozzle forming member 12 to the ink droplet 1.
3 and fly and land as dots on a recording medium (hereinafter referred to as “paper”). At this time, a desired image can be printed by selectively driving the energy generating means for applying pressure to each liquid chamber 10.

Returning to FIGS. 1 and 2, the carriage 5
The carriage 5, that is, the recording head, is connected to a timing belt 18 stretched between a driving pulley 16 and a driven pulley 17, which are rotated by a main scanning motor 15 composed of a stepping motor, and controls the driving of the main scanning motor 15. 6 is moved in the main scanning direction.

On the other hand, a platen roller (hereinafter simply referred to as "platen") 21 for transporting the paper 20 in the sub-scanning direction (the direction indicated by the arrow B in FIG. 2), and the paper 20 is disposed by being pressed against the peripheral surface of the platen 21. The paper feed rollers 22 and 23 and the pinch roller 24 for defining the paper feed angle, the guide plate 25 facing the recording head 6, the paper discharge roller 26 downstream of the recording head 6 in the paper transport direction, and the paper discharge roller 26 And a paper pressing spur roller 27 which is pressed and abutted.

Then, the rotation of the sub-scanning motor 28 composed of a stepping motor is transmitted to the platen 21 via the gears 29 to 31 and the platen gear 32, and the platen 21 is driven to rotate.
0 is sent between the recording head 6 and the guide plate 25 via the platen 21, the paper feed rollers 22 and 23, and the paper pressing roller 24, and the paper 20 is moved to the platen gear 32 while the paper 20 is moved in the sub-scanning direction by the platen 21. Meshing gear 34
The paper 20 is ejected by the paper ejection roller 26 and the paper holding spur roller 27 which are rotated through the sheet (the direction indicated by the arrow B in FIG. 2).
To send out.

In the printing apparatus thus configured, the paper 20 is conveyed in the sub-scanning direction while moving and scanning the printing head 6 (carriage 5) in the main scanning direction, and the heads 6y, 6m, 6c, 6b nozzles 8, 8 ...
, A desired color image (including a black image) is recorded on the paper 20 by discharging ink droplets of a desired color.

Further, in this recording apparatus, a reliability maintenance / recovery mechanism (subsystem) 35 for the recording head 6 is disposed on the right side of the main scanning area of the carriage 5, and when the printer is in a printing standby state, the host side When the print data is not transferred for a predetermined period of time, or at a predetermined time interval, a reliability maintenance / recovery operation such as removal of stains on the nozzle surface and nozzles of the recording head 6 is performed.

Next, the outline of the control section of the ink jet recording apparatus will be described with reference to FIG. The control unit includes a microcomputer (hereinafter, referred to as a “CPU”) 40 that controls the entire printing apparatus, and various fixed information such as information necessary for image processing such as color correction and binarization of image data. , A RAM 42 used as a working memory, etc., and a parallel input / output (P
IO) port 43, input buffer 44, character generator 45, line feed counter 46, direct memory access controller (DMAC) 47, one-line output buffer 48, and parallel input / output (PIO) port 49. I have.

This control unit is a common (Com) driver 5 for applying a drive waveform to each of the energy generating means of each of the heads 6y, 6m, 6c, 6b of the recording head 6.
0, each head 6y, 6m, 6c, 6b of the recording head 6
A driver 51 for giving a selection signal for selecting the energy generating means according to the recording signal, and a motor driver 52 for driving and controlling the main scanning motor 15 and the sub-scanning motor 28, respectively.
A required signal is output to each unit, and an operation panel (operation panel) 53 is connected. Note that a gate array (GA) can be used instead of the parallel input / output port (PIO) 49.

Here, various instructions and selection signals given from the operation panel 53 are input to the PIO 43, and various display signals and the like are output from the PIO 43 to the operation panel 53. The PIO 43 receives image data, sheet type data indicating the type of sheet, and other data from the host, and outputs various signals to the host via the PIO 43. In addition, PIO43 has
A detection signal from a paper presence / absence sensor for detecting the start and end of the paper, a signal from various sensors such as a home position sensor for detecting the home position (reference position) of the carriage 5, and the like are input.

The input buffer 44 temporarily stores print data received from the host via the PIO 43. The character generator 45 converts the printing data into image data when receiving the printing data as code data.
The line feed counter 46 counts the number of line feeds. DMAC
Numeral 47 is for reading the print data temporarily stored in the input buffer 44, converting the print data to image data by the character generator 45 if necessary, and transferring the print data for one line to the output buffer 48. Do the processing.

Further, the recording data stored in the output buffer 48 is read out at a required timing and
Is transmitted as a printing signal to the driver 5 from the PIO 49.
1 and sent to the recording head 6 from the driver 51 as a drive signal (selection signal). Also, PIO4
A drive control signal is output to the motor driver 52 via the motor 9, and the carriage 5 is moved and scanned in the main scanning direction, and the platen 21 is rotated to convey the sheet 20 by a predetermined amount.

Next, the operation of the ink jet recording apparatus will be described with reference to FIGS. First, the ink jet recording method according to the present invention will be described with reference to FIG. 6. In the ink jet recording method according to the present invention, an image is printed using both sides of OHP paper as recording surfaces. That is, when the original data (image data) as shown in FIG. 1A is printed on an OHP sheet, the data is printed on the surface of the OHP sheet P as shown in FIG. The data is also printed on the back surface of the OHP sheet P as shown in FIG.

That is, OHP paper is transparent and
In HP, a plurality of OHP originals can be used in an overlapping manner. Therefore, by printing an image on both sides of the OHP sheet, the image is viewed from one side of the OHP sheet (O
Project with HP. ) Can be viewed as an image having the same density as that of two OHP paper sheets of the same image as a whole, and a density close to the required density can be obtained even if the density of the image on each side is lowered. become able to. by this,
It is possible to compensate for a decrease in image density when using OHP paper.

Here, when inks having different physical properties are used as the Y, M, C, and K inks, images are printed on different recording surfaces of a sheet using inks having different physical properties.
For example, if black ink has different physical properties from other color inks to make the printing of monochrome text sharper, fusion between the black ink and color inks is likely to occur, or severe bleeding will occur. Therefore, image deterioration can be prevented by printing the black ink on the front surface (or the back surface) of the paper and printing the color ink on the back surface (or the front surface) to physically separate them. Note that inks having different physical properties include, for example, oil-based inks and water-based inks, and high-penetration inks and low-permeability inks, which are liable to cause image quality deterioration such as boundary bleeding when used at the same time, or are mixed. There are combinations in which the image quality, durability and the like are reduced by the combination.

Further, in this case, different image processing can be applied to the image printed on one side of the OHP sheet and the image printed on the other side. For example, an inversion process is performed so that an image printed on at least one of the surfaces is a mirror image of an image printed on the other surface so that the left and right sides are not reversed when viewed from one surface. In the example of FIG. 6 described above, the image printed on the rear surface is mirror-image-reversed with the image printed on the front surface.

Further, it is also possible to print an image on one side of the sheet with a thinning pattern and then print the image on the other side of the sheet with a thinning pattern that complements the thinning dots of the image printed with the thinning pattern. it can. For example, as shown in FIG. 7, an image is printed on the front surface of the paper P in a thinning pattern obtained by thinning out original data, and on the back surface of the paper P, a pattern of thinned dots thinned out by the image to be printed on the front surface is printed. . In this way, even if the ink and the OHP paper are a combination that relatively easily causes bleeding, it is possible to reduce the density reduction and the occurrence of bleeding.

Next, the processing performed by the control unit of the ink jet recording apparatus to execute the above ink jet recording method will be described with reference to FIG. First, as shown in FIG. 8, when the printing start process is started, the control unit determines whether or not the mode is the OHP mode for printing on OHP paper. This determination as to whether or not the OHP mode has been made can be made, for example, by checking printing mode designation information designated by the printer driver on the host side, or by providing a paper type detection sensor to determine whether the fed paper is an OHP paper. It is done by detecting whether or not.

Thereafter, in the OHP mode, a double-sided printing mode in which both sides of the OHP sheet are recorded as recording surfaces, or an OHP mode.
It is determined whether the printing mode is the single-sided printing mode in which only one side of the HP sheet is recorded as the recording side. The discrimination between double-sided printing and single-sided printing is as follows.
This can be performed by checking the printing mode designation information designated by the printer driver on the host side, or by checking the printing mode designation information inputted by selecting a switch or menu from the operation panel of the recording apparatus main body. I have to. It is also possible to separate pictograms from image data, and to automatically switch between double-sided printing and non-printing based on the color of ink used.

That is, in the case of performing double-sided printing, the printing time is relatively longer than in the case of single-sided printing.
Depending on the application and the image content, an image quality that can be used even in single-sided printing may be obtained, so that the operator or the like can arbitrarily select. For example, if the image data is text to be printed only with black ink, double-sided printing does not change much in image density. The printing time can be shortened.

In the case of the double-sided printing mode, image data is taken in, color correction processing such as gamma correction and black plate data creation is performed on the image data, and then binarization processing is performed. Various OHP correction processes such as thinning and setting of a waiting time, and multi-pass setting for performing printing on the same line in a plurality of times are performed.

Next, back-side printing data is created for the front-side printing data thus obtained. This backside printing data is mirror-inverted with respect to the front side printing data, and is the same data as the front side printing data as described above, or the back side printing is performed when the front side is printed with the thinning pattern. The side is a complementary pattern that complements the thinned dots.

Thereafter, an image is printed on the surface of the OHP sheet based on the front-side printing data thus obtained,
Next, an image is printed on the back side of the OHP sheet based on the back side printing data.

In this case, since the above-described ink jet recording apparatus does not have a reversing mechanism, after printing on the surface of the OHP sheet is completed, a message prompting the operator to revert the sheet and feed the sheet again by the printer driver. Is displayed, and back-side printing is started when the start of back-side printing is instructed while waiting until paper is fed again. If the recording apparatus is provided with a simple reversing sheet feeding mechanism or a double-sided copy conveying mechanism used in a copying apparatus or the like, the sheet can be automatically fed again.

Next, another example of the processing performed by the control unit will be briefly described with reference to FIG. 9. In this processing, in the case of the double-sided printing mode, first, image data is fetched, and On the other hand, color correction processing, binarization processing,
OHP correction processing and the like are performed to create front-side printing data, and the front-side printing data is printed on the front side of OHP paper. Thereafter, color correction processing, binarization processing, OHP correction processing, and the like are performed on the image data to create backside printing data, and the backside printing data is printed on the backside of the OHP paper. .

That is, in the processing of FIG. 8, the print data for the front side / back side is created at once, whereas in the processing of FIG. 9, after the printing on the front side is completed, Is created.

Next, another example of the processing performed by the control unit will be briefly described with reference to FIG. 10. In this processing, in the case of the double-sided printing mode, first, image data is fetched, After performing color correction processing on the back side, data for back side printing is created, and the data for front side printing and the data for back side printing are individually subjected to the binarization processing. The front side printing data is printed on the front side, and then the back side printing data is printed on the back side of the OHP sheet.

That is, depending on the image data, characters and line drawings may be included in photographs and pictures, but these characters and line drawings are regarded as part of the photographs and pictures, and are not suitable for characters and line drawings. It will be processed. There is no problem if these characters and line drawings have only the meaning of a mere pattern, but if they represent important information such as annotations and numerical values in graphs and tables, the information is more difficult to convey.

Therefore, before performing the binarization processing as in this processing, the printing data for the back side is also prepared, and thereafter, the data for the front side and the back side are subjected to different binarization processing respectively. Such a problem can be avoided. In this case, pictographic character separation performed by a facsimile or copier may be performed, but these characters and line drawings are usually represented by black, and black ink is often used with special physical properties. Can be unconditionally turned to the back side.

As described above, in this ink jet recording apparatus, an image is recorded with both sides of the OHP sheet as recording surfaces. At this time, a recording head for single-sided printing is provided, and after printing on the surface of the sheet, it is inverted or re-printed. When printing on the back side by feeding paper, the printing time is relatively long. Therefore, as shown in FIG. 11, two recording heads are provided across the paper conveyance path, and It is also possible to print the print data. In this way, it is possible to suppress an increase in the printing time and to reduce the buffer capacity on the hard disk and the hard disk for creating and storing the back side printing data when performing the processing shown in FIG. be able to.

In the above embodiment, an example is described in which both sides of OHP paper are printed as recording surfaces. However, the paper is not limited to OHP paper. It is not limited to OHP.

[0060]

As described above, according to the ink jet recording apparatus of the first aspect, since means for printing an image with both sides of the paper as recording surfaces is provided, the ink receiving layer of OHP paper or the like is thin. Even on paper, it is possible to obtain an image of a required density by preventing a decrease in image density and a merge due to overflow of ink.

According to the ink jet recording apparatus of claim 2, in the ink jet recording apparatus of claim 1,
When using inks with different physical properties, there is a means to print images on different recording surfaces of paper with inks with different physical properties, so that inks with different physical properties can be physically isolated, Problems caused by mixing of different inks can be prevented.

According to the ink jet recording apparatus of the third aspect, in the ink jet recording apparatus of the first or second aspect, each image obtained by performing different image processing on the same print data is printed on both sides of the sheet. Because of the means, it is possible to record an appropriate image according to the surface to be printed, the printed image, the purpose of use of the paper, and the like.

According to the ink jet recording apparatus of the fourth aspect, in the ink jet recording apparatus of any one of the first to third aspects, an image to be printed on one side of the sheet and an image to be a mirror image on the right and left are recorded on the other side. Since the printing unit is provided, it is possible to prevent the image from being double-shot when the image is projected in a different direction.

According to a fifth aspect of the present invention, there is provided the ink jet recording apparatus as set forth in any one of the first to fourth aspects, wherein the thinning pattern for complementing the thinned dots of the image printed on one surface of the sheet by the thinned pattern is provided. Means for printing an image on the other side, so that both sides can be thinned out to prevent merge due to ink overflow and to compensate for missing dots on the front and back sides. As a result, it is possible to prevent a decrease in image density and a deterioration in image quality due to thinning.

According to the ink jet recording apparatus of claim 6, in the ink jet recording apparatus according to any one of claims 1 to 5, when both sides of the sheet are designated to be the recording surfaces, the marking of both sides as the recording surfaces. Since there is a means to perform copying, extra time is required when printing text with only black ink that does not contribute much to density improvement even if performing double-sided and single-sided when priority is placed on printing speed over image quality. You can record without hanging.

According to the ink jet recording apparatus of claim 7, in the ink jet recording apparatus of any one of claims 1 to 6, since the printing heads are provided on both sides of the paper conveying path, the printing of the paper is performed. Recording can be performed simultaneously on the front and back surfaces, and the throughput can be reduced.

According to the ink jet recording method of the present invention, since an image is printed with both sides of the paper as recording surfaces, even if the ink receiving layer is a thin paper such as OHP paper, the image density decreases and the ink overflows. Thus, an image having a required density can be obtained by preventing merging or the like.

According to the ink jet recording method of the ninth aspect, in the ink jet recording method of the eighth aspect,
When using inks with different physical properties, inks with different physical properties print images on different recording surfaces of paper, so that inks with different physical properties can be physically isolated, and inks with different physical properties can be used. Can be prevented from being mixed.

According to the ink jet recording method of claim 10, in the ink jet recording method of claim 8 or 9, each image obtained by applying different image processing to the same print data is printed on both sides of a sheet. With this configuration, it is possible to record an appropriate image according to the surface to be printed, the printed image, the purpose of use of the paper, and the like.

According to the ink jet recording method of claim 11, in the ink jet recording method of any one of claims 8 to 10, after an image is printed on one side of the sheet, the image is printed on the other side of the sheet. Since the left image and the right image are printed, it is possible to prevent images having different directions from appearing double when viewed from one surface or when projected by OHP.

According to the ink jet recording method of the twelfth aspect, in the ink jet recording method of any one of the eighth to eleventh aspects, after printing an image on one side of the paper in a thinning pattern, the other side of the paper is printed. The image is printed with a thinning pattern that complements the thinning dot of the image printed with the thinning pattern, so that merging due to ink overflow can be prevented and missing dots on the front and back can be compensated. As a result, it is possible to prevent a decrease in image density and a deterioration in image quality due to thinning.

According to a thirteenth aspect of the present invention, in the ink jet recording method of any one of the eighth to twelfth aspects, only when both sides of the sheet are designated as the recording sides, both sides are set as the recording sides. Since printing is performed, extra time is required when printing speed is given priority over image quality, and when printing text with black ink that does not contribute much to the density improvement even if both sides are single-sided, etc. Can be recorded without.

According to the ink-jet recording method of claim 14, in the ink-jet recording method of any one of claims 8 to 13, images are simultaneously recorded on both sides of the sheet, so that the image is printed on both sides of the sheet. In this case, the throughput can be reduced.

According to the ink-jet recording method of claim 15, in the ink-jet recording method of any one of claims 8 to 14, since the sheet is a sheet for an overhead projector, an image is recorded on an OHP sheet. Sometimes the required density can be obtained with high quality images.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a mechanism of an ink jet recording apparatus to which the present invention is applied.

FIG. 2 is a schematic perspective view of a mechanism section of the recording apparatus.

FIG. 3 is a schematic perspective view of a recording head of the recording apparatus.

FIG. 4 is an explanatory sectional view of a head of the recording apparatus.

FIG. 5 is a block diagram of a control unit of the recording apparatus.

FIG. 6 is an explanatory diagram for explaining an inkjet recording method according to the present invention.

FIG. 7 is an explanatory diagram for explaining another example of the inkjet recording method according to the present invention.

FIG. 8 is a flowchart illustrating an example of a process performed by a control unit of the inkjet recording apparatus according to the present invention.

FIG. 9 is a flowchart illustrating another example of the processing performed by the control unit.

FIG. 10 is a flowchart illustrating still another example of the processing performed by the control unit.

FIG. 11 is an explanatory diagram for explaining another embodiment.

FIG. 12 is an explanatory diagram illustrating dot fusion.

FIG. 13 is an explanatory diagram illustrating the occurrence of color unevenness.

FIG. 14 is an explanatory diagram illustrating a conventional printing method for OHP paper.

[Explanation of symbols]

Reference numeral 5: carriage, 6: recording head, 15: main scanning motor, 21: platen, 28: sub-scanning motor.

Claims (15)

[Claims] 1. An ink jet recording apparatus for recording an image by ejecting ink droplets onto a sheet, comprising means for printing an image with both sides of the sheet as recording surfaces. 2. The ink jet recording apparatus according to claim 1, further comprising means for printing an image on a different recording surface of the paper with ink having different physical properties when using inks having different physical properties. Inkjet recording apparatus. 3. An ink jet recording apparatus according to claim 1, further comprising means for printing each image obtained by applying different image processing to the same print data on both sides of said paper. Inkjet recording apparatus. 4. An ink jet recording apparatus according to claim 1, further comprising means for imprinting an image to be printed on one side of the sheet and an image to be a mirror image on the left and right sides on the other side. An ink jet recording apparatus comprising: 5. The ink jet recording apparatus according to claim 1, wherein an image is printed on the other surface of the sheet by using a thinning pattern that complements a thinning dot printed on one surface of the sheet by the thinning pattern. An ink jet recording apparatus comprising means for printing. 6. The ink-jet recording apparatus according to claim 1, further comprising: means for performing printing with both sides of the sheet as recording surfaces when designation is made of both sides as recording surfaces. An ink jet recording apparatus characterized in that: 7. The ink jet recording apparatus according to claim 1, further comprising printing heads on both sides of the paper conveyance path. 8. An ink jet recording method for recording an image by ejecting ink droplets onto a sheet, wherein the image is printed using both sides of the sheet as recording surfaces. 9. The ink jet recording method according to claim 8, wherein when using inks having different physical properties, the inks having different physical properties print images on different recording surfaces of the paper. Method. 10. The ink jet recording method according to claim 8, wherein each image obtained by applying different image processing to the same print data is printed on both sides of the paper. Method. 11. The ink jet recording method according to claim 8, wherein after printing an image on one surface of the paper, the printed image and a left and right mirror image are printed on the other surface of the paper. An ink jet recording method characterized by printing an image to be formed. 12. The ink jet recording method according to claim 8, wherein an image is printed on one surface of the paper in a thinning pattern, and then printed on the other surface of the paper with the thinning pattern. An ink jet recording method, comprising printing an image with a thinning pattern that complements the thinning dots of a copied image. 13. The ink jet recording method according to claim 8, wherein printing is performed with the both sides of the sheet as the recording surface only when the both sides of the sheet are designated as the recording surface. Characteristic ink jet recording method. 14. The ink jet recording method according to claim 8, wherein an image is recorded on both sides of the sheet at the same time. 15. The ink jet recording method according to claim 8, wherein said paper is a paper for an overhead projector.