JP2963032B2 - Printing apparatus and printing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus and a printing method, and more particularly, to an apparatus and a method for performing multi-value printing by forming dots on a printing medium such as paper and changing the area or density of the dots. It is about.

[0002]

2. Description of the Related Art Conventionally known multi-value printers (printing apparatuses) employ a printing method such as an ink jet method, a thermal transfer method, a thermal sublimation method, a silver salt method, and the like.
In these types of printers, when forming each pixel, the area or density of the dot formed in the pixel is changed by changing the energy applied to the printing element, thereby performing multi-value printing. For example, in a thermal sublimation type printing apparatus, a large energy is applied to a pixel to be printed at a high density to generate a large amount of ink sublimation to form a large dot.

[0003]

However, in the conventional printing apparatus, when performing the multi-value printing as described above,
The energy applied to each of the plurality of print elements of the print head must be different,
As a result, there has been a problem that the configuration for driving the print head is relatively complicated and expensive.

That is, in order to make the applied energy different for each print element, it is necessary to provide at least a signal line relating to the applied energy for each print element, and therefore, the structure of the head and its drive control is relatively complicated. And other problems.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a printing apparatus and a printing method capable of simplifying a configuration relating to driving of a print head. Is to provide.

[0006]

According to the present invention, there is provided:
In a printing apparatus that prints a gradation image on a print medium using a print head having a plurality of print elements each capable of outputting dots of at least two gradations, the print head is applied to the same portion of the print medium a plurality of times. Scanning control means for performing scanning, and output control means for changing a gradation level of a dot formed in the same pixel by each of the printing elements in a plurality of scans of the print head by the scanning control means , Control means
Is applied to a plurality of pixels in each of the plurality of scans.
The present invention is characterized in that there are at least two types of gradation levels of dots to be formed .

In a printing method for printing a gradation image on a print medium by using a print head having a plurality of print elements each capable of outputting dots of at least two gradations, the same method may be applied to the same portion of the print medium. the printhead is scanned a plurality of times, in a plurality of scans of the print head, to vary the gray level of the dot which forms the same pixel by the respective printing elements, a step
A plurality of pixels in each of the plurality of scans
The number of gradation levels of the dots to be formed in at least two types
Characterized in that that.

According to the above arrangement, when multi-value printing is performed by a plurality of scans of the print head, the gradation levels of dots formed in the same pixel in the plurality of scans are different. In this case, the gradation level of the dots to be formed can be the same among a plurality of pixels.

[0009]

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

(First Embodiment) FIG. 1 is a block diagram showing a configuration of a printing system using an ink jet type printing apparatus according to an embodiment of the present invention. It can be.

In FIG. 1, a CPU 1 executes data processing, operation control, and the like in the system according to a program stored in a ROM 2. The RAM 4 stores the CPU 1
Is used as a work area when executing data processing and the like. An operator's instruction input regarding these data processing and the like can be made via the keyboard 3.

An original image buffer 5 temporarily stores image data read by an image scanner 6, image data read from a hard disk of a hard disk drive (HDD) 7, or processed image data in the present system. Buffer memory. As shown in FIG. 2, the original image buffer 5 has R (red), G (green), B
The image scanner 6 stores an 8-bit signal of 256 gradations for each of (blue), and reads an 8-bit signal of R, G, and B at a resolution of 90 dpi by the A / D conversion.

The R, G, and B image data stored in the original image buffer 5 is subjected to a predetermined color conversion by the processing of the CPU 1 and converted into Y (yellow), M (magenta), and C (cyan) data. After the conversion, predetermined image processing such as logarithmic conversion, masking, and γ correction is performed, and finally, ternary processing is performed on the Y, M, and C image data. Thereby, for each pixel (Y0, M0, C
0), (Y1, M1, C1) or (Y2, M2, C
Any of the print data of 2) is obtained, and these are temporarily stored in the print buffer 8. That is, as shown in FIG. 3, the print buffer 8 stores data Y0, M0, and C0 (not shown) indicating none, small, and large for the sizes of the dots to be formed for each of Y, M, and C, respectively. , Y1, M1, C1 and Y2, M2, C2.

The display 9 has a color liquid crystal panel and can display image data stored in the display buffer 10. The display 9 is capable of displaying 16 gradations for each of R, G, and B. That is,
The image data stored in the display buffer 10 is the same as the image data stored in the print buffer
By performing the gradation conversion on the data obtained through the above-mentioned steps, the image data of the above 16 gradations can be obtained.

The printer 12 is a printing apparatus to which the present invention is applied. The printer 12 uses the above-described printing system as a host apparatus, and performs printing based on print data stored in the print buffer 8 from this apparatus.

FIG. 4 is a block diagram mainly showing a control configuration of the printer 12.

As shown in the figure, the printer 12 has Y, M,
Print heads 100Y and 10 for ejecting each ink of C
0M and 100C, which are mounted on the carriage 110 and can perform printing by discharging ink onto a print medium such as paper during scanning of the carriage.

The CPU 101 controls the data processing and operation of the printer 12 as a whole, including the printing operation of the printer 12. The ROM 102 stores the control procedure, and the RAM 103 stores the CPU 101
Is used as a work area for the execution of processing by.

Print head 100 used in this embodiment
Y, 100M, and 100C can have a simplified configuration by applying the present invention, as will be described later with reference to FIG.
4 and its control signal generation circuit and the like (not shown) can also have a simpler configuration.

The carriage 110 includes a carriage motor 1
09 is a driving source, and its operation is controlled via a motor driver 108. At the same time, the rotation of the paper feed roller 107 for transporting the print medium is controlled via the motor driver 105 using the paper feed motor 106 as a drive source.

FIG. 5 is a diagram schematically showing a configuration for driving the print heads 100Y, 100M, and 100C used in the printer 12. As shown in FIG.

A piezo element 25 as a printing element is provided corresponding to each ink discharge port of the print head, and can discharge ink by the electro-mechanical conversion energy generated by each element 25. Piezo element 25
Is connected to a common electrode wiring 30 at one end to drive the wiring, and the wiring 30 is connected to a predetermined power supply.
On the other hand, the driver 22 is connected to the other end of the piezo element 25 so that the driving of the piezo element 25 can be controlled. That is, the ejection signal is input to each driver 22 via the signal line 26. The ejection signal is a signal for performing ink ejection at a predetermined timing during the printing operation by the print head, that is, corresponding to each pixel. "" Means no ejection. In addition, each driver 2
Pulse data is input to 2 via a signal line 24.
The pulse data is, for example, a signal corresponding to the above-described ternary print data Y1 and Y2 in the case of a yellow head. When the dot is “0”, the pulse width applied to the piezo element by the driver 22 is determined corresponding to each of the small dots formed with a small ejection amount.

The processing operation based on the apparatus configuration of the present embodiment shown in FIGS. 1 to 5 will be described with reference to the flowchart shown in FIG. The processing procedure shown in the figure schematically shows the procedure in the system of FIG. 1 corresponding to the host device of the printer 12 and the printer 12, and the procedure shown in the figure is not always performed continuously.

First, in step S 1, the system shown in FIG. 1 reads a desired image to be printed from the HDD 7 and stores it in the original image buffer 5. next,
R, G, B 256 stored in the original image buffer 5
The gradation image data is converted into the above-described ternary print data of Y, M, and C and stored in the print buffer 8.

In the above state, the printer 12 starts a printing operation when a print command is received from the host system shown in FIG.
0, and print data Y1, M1,
Printing is performed by ejecting ink from each head to the pixel having C1. That is, a pulse having a width corresponding to the data Y1, M1, and C1 is applied to the piezo element corresponding to the pixel via the signal line 24 shown in FIG. 5, and a small dot shown in FIG. Is formed. FIG. 2B shows a case where all the pixels have data Y1, M1 or C1.

Next, in step S4, the carriage 11
0 in the backward scan, the print data Y2, M2, C2
Is performed by ejecting ink from each head to the pixels having. That is, at this time, a pulse having a larger width according to the data Y2, M2, and C2 is applied to the piezo element corresponding to the pixel via the signal line 24, and a large dot shown in FIG. 7A is formed. You.

The above processing of steps S3 and S4 is performed until printing of all data is completed (step S5), and the processing is terminated. FIG.
The pixel shown in (c) has all the print data Y
0, M0 or C0, that is, a case where no dot is formed. By performing the printing based on the print data for each pixel stored in the print buffer 8 by the above processing, for example, the image shown in FIG. 8 can be printed. Here, the vertical pixels in the figure correspond to the respective ink ejection ports of the print head.

As is apparent from the above description, according to the present embodiment, in each of the forward and backward scanning of the carriage 110, the pulse data applied to each piezo element 25 is:
Each of them is of the same kind.
As shown in part of the drive circuit configuration of the print head,
Since it is not necessary to change the pulse data for each ejection timing, such as the fact that the piezo elements as print elements can be shared without being individual for each piezo element, a configuration for supplying a pulse control signal related to head drive is provided. It can be simplified.

In the application of the present invention, it is apparent that the pulse data does not necessarily have to be of the same type during the same scan, and that at least the pulse data for simultaneously ejecting the inks need only be of the same type. It is.

In the above-described embodiment, a print head for discharging K (black) ink is not used, but this head can be further used. In this case, in the above-described image processing, under color removal (UCR) processing,
Black generation processing is performed.

(Second Embodiment) In the first embodiment described above, pulse data of the same type is used during the same forward or backward scan. However, in the present embodiment, the print head configuration is changed. 9, the type of pulse data applied to each piezo element 25 is the same for every other array of piezo elements 25, and two types of pulse data can be applied simultaneously. To For example, when the pulse width data input to the signal line 24 is "1", the driver 22A can apply a pulse for forming a large dot to the corresponding piezo element 25. Since the data becomes "0", the driver 22B can apply a pulse for forming a small dot to the corresponding piezo element. On the other hand, when the pulse width data supplied to the signal line 24 is “0”, the pulses that can be applied by the drivers 22A and 22B have a relationship opposite to that described above.

FIG. 10 is a diagram showing an example of printing using the print head having the above configuration. As shown in FIG. 9A, when the pulse data is “1”, the scanning is forward or backward. For example, when the ejection signals of all the pixels are “1”, the size is vertically larger or smaller like a dot row 19. Dots are formed in the order of
On the other hand, when the pulse data is “0”, dots are formed in the order of small, large and small as shown in the dot row 20 as shown in FIG.

(Third Embodiment) FIGS. 11A and 11B are views showing a print example according to still another embodiment of the present invention.

In the embodiment shown in this figure, pulse data supplied to the signal line 24 is alternately changed at each ejection timing in the scanning of the carriage 110 using the print head having the structure shown in FIG.

In each of the embodiments described above, an ink jet printing apparatus using a piezo element has been described. However, the application of the present invention is not limited to such a printing apparatus. The present invention can be applied not only to the ink jet system or the ink jet system, but also to a printing apparatus such as a wire dot system or a thermal transfer system.

[0036]

As is apparent from the above description, according to the present invention, when multilevel printing is performed by scanning the print head a plurality of times, the gradation of the dots formed on the same pixel by the plurality of scans. Since the levels are different, the gradation level of the dots formed in each scan can be the same among a plurality of pixels. This eliminates the need to control the dot gradation level for each print element,
The configuration for driving the head can be simplified.

As a result, it is possible to obtain a cheaper printing apparatus.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a print system according to an embodiment of the present invention.

FIG. 2 is a diagram schematically showing the contents of an original picture buffer shown in FIG.

FIG. 3 is a diagram schematically showing the contents of a print buffer shown in FIG. 1;

FIG. 4 is a block diagram mainly showing a control configuration of the printer shown in FIG. 1;

FIG. 5 is a diagram schematically showing a circuit configuration for driving a print head used in the printer according to the first embodiment of the present invention.

FIG. 6 is a flowchart illustrating a print processing procedure according to the first embodiment of the present invention.

FIGS. 7A, 7B and 7C are schematic diagrams showing dot arrays printable by the printer according to the first embodiment. FIGS.

FIG. 8 is a schematic diagram illustrating a print example by the printer according to the first embodiment.

FIG. 9 is a diagram schematically illustrating a circuit configuration for driving a print head according to a second embodiment of the present invention.

FIGS. 10A and 10B are schematic diagrams showing a dot array that can be printed according to the second embodiment.

FIGS. 11A and 11B are schematic diagrams showing a dot array printable according to a third embodiment of the present invention.

[Explanation of symbols]

 1,101 CPU 2,102 ROM 3 keyboard 4,103 RAM 5 original image buffer 6 image scanner 7 HDD 8 print buffer 9 display 10 display buffer 11 FDD 12 printer 22 driver 25 piezo element 100Y, 100M, 100C print head 107 paper feed Roller 110 carriage

Claims (6)

(57) [Claims] 1. A printing apparatus for printing a gradation image on a print medium using a print head having a plurality of print elements each capable of outputting dots of at least two gradations. Scanning control means for scanning the print head a plurality of times, output control means for varying the gradation level of dots formed in the same pixel by each of the print elements in the plurality of scans of the print head by the scan control means, Wherein the output control means comprises:
In this case, the gradation level of the dots formed in a plurality of pixels
Wherein at least two types are used. 2. The method according to claim 1, wherein the output control unit sets at least two types of gradation levels of dots formed in a plurality of pixels corresponding to the plurality of print elements in each of the plurality of scans. Item 6. The printing device according to Item 1 . 3. The output control means sets at least two gradation levels of dots to be formed in a plurality of pixels corresponding to each dot formation timing in each of the plurality of scans.
The printing apparatus according to claim 1 or 2, characterized in that the type. 4. The method according to claim 1, wherein the output control means is configured to perform the plurality of scans.
At least two types of dots formed in each
Change the gradation level alternately at each dot formation timing
The printing apparatus according to claim 3, wherein Wherein said printing element, by discharging at least two kinds of amounts of ink, according to claim 1, wherein the possible dots output of at least 2 gradation
The printing device according to any one of the above. 6. A printing method for printing a gradation image on a print medium by using a print head having a plurality of print elements each capable of outputting dots of at least two gradations, wherein the printing is performed on the same portion of the print medium. Scanning the print head a plurality of times, in the plurality of scans of the print head, different gradation levels of dots formed in the same pixel by each print element, comprising the steps of:
At least the gradation level of dots formed in a plurality of pixels
A printing method characterized by two types .