JPH02289355A - Image recorder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an image recording device.

[Prior Art] Conventionally, as an image recording device, an inkjet recording device that performs printing (recording) by ejecting ink onto a recording material is known.

Inkjet recording devices are non-impact recording devices with features such as low noise and the ability to easily record color images by using multicolored inks, and have become rapidly popular in recent years. be.

FIG. 10 is a schematic perspective view of a conventional inkjet recording apparatus.

The recording material 5 wound into a roll in FIG. Sent in the middle f direction. A guide rail 6.7 is placed in parallel across the recording material 5, and a recording head 9 mounted on a carriage 8 scans left and right. Each carriage 8 has a plurality of ink ejection ports arranged in parallel, yellow,
Heads 9Y and 9M available in four colors: magenta, cyan, and black.
.

9C and 98K are installed, and four color ink tanks are arranged correspondingly. The recording material 5 is a recording head 9
While the recording material 5 is stopped, the recording head 9 scans in the P direction and ejects ink droplets corresponding to the binarized image signal.

In such an inkjet recording apparatus, the characteristics of the recording material are important, and in particular, the bleeding characteristics of the ink on the recording material have a large effect on image quality.

A "bleeding rate" is known as an index indicating the ink bleeding characteristics of a recording material. This indicates how many times the diameter of an ink droplet ejected from an inkjet nozzle spreads on the recording material, and is given by: Bleeding rate: diameter of the dot on the recording material/diameter of the ejected ink droplet. For example, the diameter of ink droplets in flight is 30 μm.
If a dot of 90 μm is formed on the recording material, the bleeding rate of the recording material will be 30.

A recording material with a low bleeding rate has a low image density, making it difficult to obtain a high-quality image with texture.

[Problem to be Solved by the Invention 1] On the other hand, recording materials with a high bleeding rate have high image density, but the following problems have occurred.

In a serial scan type inkjet recording apparatus as shown in FIG. 1θ, as shown in FIG. Same figure (1).

Repeat steps (2) and (3) in this order. The width d is determined by the number of ejection ports of the head and the recording density, and is determined by the number of ejection ports of the head, 256. Recording density 400 dots/inch (dpi
), 256x 25.4/400= 16.
It becomes 256mm.

When the amount of ink recorded is small, the ink absorption of the recording material is sufficient, so the width of the recorded image is equal to the recording width d.
almost equal to For this reason, if printing is performed in six directions after scanning the printing head by d in the B direction, as shown in FIG. 11(A).
As shown in the figure, the seams between each recording scan do not pose a problem on the image.

However, when recording an image in a high-density area, that is, a part where a large amount of ink is ejected onto a recording material, a recording material with a large bleeding rate cannot absorb enough ink, and the ink bleeds in the horizontal direction. The recorded image width is d+
It becomes Δd. At this time, if the scanning width of the recording head in the B direction is d, the images overlap with a width of Δd, and the 11th
As shown in Figure (B), black streaks occur in this portion. Conversely, if the scanning width in the B direction is set to d+Δd, white streaks will appear in low-density areas where the amount of ejected ink is small.

The amount of image width expansion Δd in the high-density area changes depending on the bleeding rate of the recording material and the positive ink ejected onto the recording material.
The larger the bleeding rate and the larger the amount of ink, the larger Δd becomes. Therefore, in order to prevent the occurrence of black streaks, it is necessary to use a recording material with a low bleeding rate or to reduce the amount of ink used for recording, but in this case, as mentioned above, the image density will decrease. , a problem arises in that a high-quality image with a solid texture cannot be obtained.

In order to solve such problems, the applicant proposed in Japanese Patent Application No. 63-148229 that when the value of a multi-level image signal that is generally at the boundary of a serial scan is large, the recording involved in the recording of the boundary is We have proposed an image recording device that prevents black streaks in high-density areas by performing processing to reduce the value of the image signal recorded by the element.

However, many image recording apparatuses, especially inkjet image recording apparatuses, use a binary recording method that records dots or not, and therefore do not record dots in response to a multi-value input signal. Since it does not have a conversion processing section, it is often not possible to input multivalued image signals as they are.

In such a case, in order to perform the processing related to the above-mentioned Japanese Patent Application No. 63-148229, it is necessary to add a function to perform such processing to the external device that performs image processing, and as a result, various images The generality of the human input signal to the recording device would be compromised.

[Means for Solving the Problems] In order to solve these problems, the present invention provides an image recording device that records a predetermined image by scanning a plurality of times while printing dots. a calculation means that performs a predetermined calculation using the number of printed dots in the adjacent portion of the unit image formed by each scan; and a modulation device that controls the printing state of the adjacent portion of the unit image based on the calculation result of the calculation means. It is characterized by having a means.

Further, the present invention provides an image recording apparatus that has a recording head in which a plurality of recording elements are arranged side by side and records an image by serially scanning the recording head, in which a binarized image signal corresponding to a boundary between scans is stored. A calculation means that performs a predetermined calculation using the binary image signal omitted in the notation f, 9 means, and t0 means, and a recording element involved in recording the boundary portion according to the result of the calculation. The present invention is characterized by comprising at least one of a converting means for converting the number of dots recorded by the recording element and a modulating means for modulating the area of the dots recorded by the recording element involved in recording the boundary.

[Function] According to the present invention, the volume of the ejected ink droplet, that is, the area of the formed dot, can be modulated to some extent by, for example, modulating the driving energy applied when the ink droplet is ejected. In addition to manual serial scan type inkjet printers, it is possible to reduce the number of dots that cannot be recorded by the ejection nozzles at the boundaries of scanning in areas with high density, that is, areas where a large amount of ink is ejected onto the recording material. By reducing the area, it is possible to obtain high-quality images without black streaks in high-density areas.

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

(No. 1 Example) FIG. 1 shows a first embodiment of the invention.

Here, 9 is, for example, an inkjet head that applies electrical energy to a resistor that generates heat in response to energization (heating resistor) to heat and foam the ink, and ejects ink droplets using the pressure generated by the foaming. 11 is a buffer memory, 12 is an arithmetic processing unit, and 13 is a buffer memory.
4 is a recording dot number conversion processing section, and 4 is a recording dot number conversion processing section.

In general, a multi-value human image signal that is supplied from an image reading unit (not shown) or an external device is subjected to color correction, edge enhancement, and other processing in the external device, and then processed by the binarization processing unit (not shown) of the external device. 2 using the dither method, error diffusion method, etc.
Valued. The signals are represented by "0" and "1", with "l" indicating the presence of a recording dot and 'O' indicating the absence of a recording dot.

In the scanning direction (
Several pixels (for example, 16 pixels) are stored in the buffer memory lI in the direction of A in FIG. Perform calculations such as dividing by the whole number.

Then, in accordance with the output signal of the arithmetic processing section 12, the area modulation processing section 14 calculates the electric energy applied to the heat generating resistor that records the boundaries of each scan, for example, as shown in FIG. Dot area modulation such as lowering the dot area. Note that the electrical energy may be modulated by modulating the width and/or voltage value of the pulse applied to the heating resistor, or by changing the shape of the pulse.

As an example, as shown in Figure 3, it has been experimentally found that the volume of ejected ink decreases when the applied electrical energy is lowered, so the area of the dots formed on the wave recording material becomes smaller. Therefore, Δd shown in FIG. 11 becomes smaller, and the problem of black streaks is improved. Note that, as shown in Figure 3, the width of dot area modulation is generally narrow, especially in inkjet recording devices, and the dot area modulation range from highlight areas to half) area to dark areas is generally narrow. It is extremely difficult to express all gradations, and the above two
It is difficult to omit the value processing.

Since the area modulation width of recording dots is generally narrow, in order to more effectively improve black streaks, in this example, the number of dots is changed as needed, for example, as shown in FIG. Make sure to thin it out. This can be done, for example, by appropriately thinning out the number of energizing pulses applied to the heating resistor. By performing such dot number conversion processing, black streaks can be more effectively improved.

Note that the binarized image signal inputted to the recording element in the non-boundary area is inputted directly to the head 9 without any processing.

(Second Embodiment) In the first embodiment, the binarized image signal input to the recording element at the boundary is stored, and as an example of arithmetic processing, an operation of simply adding and dividing by the total number is performed. Ta. Therefore, when the number of dots to be recorded by one recording element at the boundary is large, the number of dots is thinned out or the area of the recorded dots is reduced.

However, when processing is performed as described above, dots may be thinned out even if by chance an image in which a thin line with a width of one dot is to be recorded by the recording element at the boundary is manually created, and the dot area may be As a result, an image that should be a line may be cut into pieces, or the line may become thinner than necessary.

This embodiment is an improvement to avoid such inconvenience.

FIG. 5 is an explanatory diagram of this embodiment.

This figure 5 shows a matrix of the human input image signal that has been converted into a binary image, where the 1st row is the image signal input manually to the endmost recording element that records the scan boundary, and the m row is the endmost image signal. The image signal inputted to the second recording element from the end is the image signal inputted manually, and the image signal inputted to the third recording element from the end is inputted manually from the nth row. In this example, the number of pixels in the scanning direction (direction to in FIG. 11) to be stored is 8 pixels.

In this example, the arithmetic processing unit multiplies the 0" or "l" signal input into the matrix M by a weighting coefficient provided for each element in the matrix, and adds them. It will be held on 12th.

FIG. 6 shows an example of the weighting coefficient matrix M'. In this example, the normalization coefficient l/88 is multiplied so that the maximum output signal becomes 1. Then, by performing dot area modulation processing and dot number conversion processing similar to those shown in FIGS. 2 and 4 in accordance with the output signal of the arithmetic processing unit 12, black lines can be eliminated without causing the above-mentioned problems. can be effectively prevented from occurring.

(Third Embodiment) FIG. 7 is a block diagram of an inkjet recording apparatus capable of full-color recording according to a third embodiment of the present invention.

Here, in the 9 tree examples in which elements with the same reference numerals as those in FIG. Cyan (C),
For each of magenta (M), yellow (Y), and black (Bk), several pixels are stored in the scanning direction (direction of A in FIG. 11), for example, 166 pixel buffers 11cj1M, IIY
, save it to 118k. Then, among those 166 pixels, the number of pixels whose signal is "l" is c, m, y, b, respectively.
When k, the arithmetic processing unit 12-1 performs the calculation S1=(c+m+y+bk)/1B.

In accordance with the calculation result of the calculation processing section 12-1, dot area modulation processing is performed by the recording dot area modulation processing section 14 as shown in FIG. 8, for example. On the other hand, the arithmetic processing unit 12-1
According to the calculation result, the recording dot number change I moxibustion processing section 13 performs dot number conversion processing as shown in FIG. The calculation is performed on each color head 9C,
It is distributed and supplied to 9M, 9Y, and 98K.

C: (c/c+++++y+bk)-52M:
(m/c+m+y+bk)-52Y: (y/c
+m+y+bk) ・52BK: (bk/c+m+
y+bk)・S2 By performing such dot area modulation processing and dot number conversion processing, C, M, Y,
It is possible to prevent black streaks more effectively than by performing the processing as in the first embodiment on each of B independently.

Note that in this example, calculations were performed based on the binarized human image signal for one recording element at the boundary.
As in the second embodiment, it is also possible to perform matrix processing on human image signals for several recording elements, and in this case, a higher quality image can be obtained without the risk of causing the above-mentioned disadvantages. It's obvious.

In the first to third embodiments described above, processing is performed to reduce the number of dots and dot area for one recording element located at the end of the recording elements involved in recording at the scan boundary. However, it goes without saying that similar processing may be performed on a plurality of recording elements near the boundary.

At this time, the number of dots and the dot area need not necessarily be reduced uniformly for each recording element.

Further, the printing elements at the boundary part related to the above-described processing may be printing elements at both ends of the printing head involved in printing, or may be printing elements at one end side.

Furthermore, the number of elements related to the shapes of the curves, the dot number conversion process, and the dot area modulation process shown in FIGS. 2, 4, 8, and 9 depends on the recording material, ink,
They may be set appropriately depending on the ink ejection characteristics and other unique characteristics of the head.

Further, in the first to third embodiments described above, both the dot number conversion process and the dot/area modulation process are performed, but either one of them may be performed.

In addition, although the case where the present invention is applied to an inkjet recording device was explained in Uebi, the present invention can be applied very effectively and easily to image recording devices where bleeding is a problem, such as thermal transfer printers using sublimable dyes. Of course, it can be applied to.

[Effects of the Invention] As explained above, according to the present invention, for example, in a serial scan type image recording device for binary recording, which cannot be performed manually with multi-level data, recording is performed by the recording elements involved in recording the boundaries of each scan. By providing a relatively simple means for converting a large number of dots into a smaller number and/or modulating the dot area to a smaller size, special functions can be added and manual input signals to the printer can be reduced. This makes it possible to record high-quality images without black streaks in high-density areas with many recording dots, without compromising the generality of the technique.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of the present invention, and FIG. 2 is an explanatory diagram showing the relationship between the arithmetic processing unit output signal and applied electrical energy according to the first and second embodiments of the present invention. , FIG. 3 is an explanatory diagram showing the relationship between applied electrical energy and ejected ink volume, and FIG. 4 is an explanatory diagram showing the relationship between applied electric energy and ejected ink volume. FIG. FIG. 5 is an explanatory diagram showing the human input image signal matrix according to the second embodiment of the present invention. FIG. 6 is a weighting coefficient according to the second actual tJ & example of the present invention. FIG. 7 is a block diagram showing the third embodiment of the present invention, and FIG. 8 is an explanatory diagram showing the matrix, and FIG. FIG. 9 is an explanatory diagram showing the relationship between the output signal of the arithmetic processing section and the output signal of the recording dot number conversion processing section according to the third embodiment of the present invention, and FIG. A perspective view showing a configuration example of a color inkjet printing apparatus as a printing apparatus to which the invention can be applied. FIGS. 11A and 11B are explanatory diagrams for explaining the mechanism of black streak occurrence. 5...recording material, 9.9Y, 9M,! l(1:, 98K... Inkjet head, 11, IIY, IIM, IIC, IIB... Buffer memory, 1242-1.12-1...
- Arithmetic processing unit, I3... Recording dot number conversion processing unit, 14... Recording dot area modulation processing unit, 15... Sub-scanning motor. Fig. Input force ot Qi energy λ10 (J) Fig. Fig. Fig. Fig. Fig. 2.

Claims (1)

[Claims] 1) An image recording device that records a predetermined image by scanning a plurality of times while printing dots, the image recording device comprising: an adjacent portion of a unit image formed by each of the plurality of scans; An image recording device comprising: a calculation means for performing a predetermined calculation using the number of printed dots in the calculation means; and a modulation means for controlling the printing state of an adjacent portion of the unit image based on the calculation result of the calculation means. . 2) The image recording apparatus according to claim 1, wherein the predetermined calculation using the number of printed dots is a calculation for obtaining a total sum of printed dots in adjacent areas. 4) In an image recording apparatus that has a recording head in which a plurality of recording elements are arranged side by side and records an image by serially scanning the recording head, a memory that stores the binarized image signal corresponding to the boundary between the scans. means, a calculation means for performing a predetermined calculation using the binary image signal stored in the storage means, and dots recorded by the recording element involved in recording the boundary portion according to the calculation result. An image recording apparatus comprising at least one of a converting means for converting the number of dots and a modulating means for modulating the area of dots recorded by the recording element involved in recording the boundary portion. 5) The image recording apparatus according to claim 4, wherein the recording element has a recording ink ejection opening and an ejection energy generating element disposed corresponding to the ejection opening. 6) The ejection energy generating element includes a heating resistor configured to heat the ink and foam it by generating heat in response to energization, and eject ink droplets using the resulting pressure. image recording device. 7) The image recording apparatus according to claim 6, wherein the modulating means modulates the amount of electrical energy applied to the heating resistor. 8) The image recording apparatus according to claim 6, wherein the modulating means changes the shape of a pulse applied to drive the heating resistor. 9) The image recording apparatus according to claim 7, wherein the modulating means modulates the width and/or voltage value of the pulse in order to change the amount of applied electrical energy. 10) The image recording apparatus according to claim 6, wherein the converting means changes the number of pulses applied to the heating resistor.