JPS61293863A - Tone expression of ink jet printing device - Google Patents

Abstract

PURPOSE:To obtain a satisfactory gradation linearity and to enable expression of multi-gradation, by controlling ink droplet discharge from nozzles by ink discharge driving signals that are put out continuously in numbers correspondingly to the extent of the gradation, and by discharging the ink in quantities which correspond to the degrees of the gradation to the dot positions as fixed. CONSTITUTION:Based on printing data, a controller 12 is driven; and synchronized with the motion of a head, a gradation signal generation circuit 13 and a gradation printing timing generation circuit 14 are controlled. And from the gradation signal generation circuit 13, an ink discharge signal based on a control signal of the controller 12 is put out by a clock signal from the timing generation circuit 14. Then, it becomes a signal to discharge an ink droplet from a nozzle through an ink discharge driving circuit 15, and the nozzle is driven to discharge the ink. Inasmuch as the number of dots and the configuration are fixed as above, the gradation linearity is extremely good. In addition, since the ink quantities that are equally divided in several times corresponding to the extents of gradations are continuously discharged, even in multi- gradation expression, the ink discharge amounts from the nozzles are constant, and the stability of the nozzles and the discharge ink droplets is obtainable, resulting in an easy multi-gradation expression.

Description

Translated fromJapanese

【発明の詳細な説明】〈産業上の利用分野〉本発明は、インクジェット印刷装置を用いて実施する印
刷物の階調表現方法（印刷物の製造方法）に関するもの
である。DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for expressing gradations in printed matter (a method for producing printed matter) that is carried out using an inkjet printing device.

〈従来の技術〉従来、インクジェット印刷装置における階調表現方法と
しては、４階調を示した第５図（ａｌ〜（ｄ）図及び９
階調を示した第６図（ａ）〜（１）図のように、■単位
面積当りのドツトの数を階調度に応じて可変する面積階
調方法と、■オンデマンド型プリンタ等に用いられてい
る方法であって、ドツト数を一定としてインク吐出用の
駆動電圧又はパルスの幅を階調に応じて制御することに
より、１つのドツトのインク量を可変してドツトの大き
さを階調に対応して可変させる方法とがある。<Prior art> Conventionally, as a gradation expression method in an inkjet printing device, the methods shown in FIGS.
As shown in Figures 6 (a) to (1) showing gradations, there is an area gradation method in which the number of dots per unit area is varied according to the gradation degree, and This is a method in which the number of dots is kept constant and the ink ejection drive voltage or pulse width is controlled according to the gradation, thereby varying the amount of ink for one dot and varying the size of the dot. There is a method of varying it depending on the key.

〈発明が解決しようとする問題点〉しかしながら、前記■の方法では、非階調の場合と同じ
ドツト密度に抑えようとすれば、４階調の時縦と横のド
ツト数をそれぞれ２倍にしなければならず、この場合、
非階調時と比較して同一の面積を同一の時間で印刷する
には、ヘッドの走行スピードを２倍に、且つインク吐出
駆動周波数を４倍にする必要があり、駆動周波数を４倍
にすることは可能であるが、ヘッドの走行スピードを２
倍にすると、インクタンク内のインクの揺れが激しくな
ったり、ヘッドのドライブモータが大型化するなど困難
な問題が多い。しかも、第５図及び第６図から明らかな
ように、ドツトの分布が均一でないから階調リニアリテ
ィが良好とは言い難く、不自然な階調表現となる欠点が
ある。<Problem to be solved by the invention> However, in the method (2) above, in order to suppress the dot density to the same as in the non-gradation case, the number of vertical and horizontal dots must be doubled for four gradations. In this case,
In order to print the same area in the same time compared to non-gradation, it is necessary to double the head running speed and quadruple the ink ejection drive frequency; It is possible to do this, but if the running speed of the head is
Doubling the size will cause many difficult problems, such as the ink in the ink tank becoming more violent and the head drive motor becoming larger. Moreover, as is clear from FIGS. 5 and 6, since the distribution of dots is not uniform, it is difficult to say that the gradation linearity is good, resulting in an unnatural gradation expression.

一方、前記■の方法によると、階調リニアリティは■の
方法の場合よりは良好であるが、階調度が大きくなる程
ノズルから連続して吐出される１回当りのインク量が多
くなり、且つインク吐出時間が長くなるから、ノズルの
性能性、吐出インク液滴及びノズルの安定性に問題があ
り、多階調の表現には限度があり実用化に至っていない
。On the other hand, according to the method (2), the gradation linearity is better than that of the method (2), but the larger the gradation level, the larger the amount of ink that is continuously ejected from the nozzle. Since the ink ejection time becomes long, there are problems with the performance of the nozzle, the stability of the ejected ink droplets and the nozzle, and there is a limit to the expression of multiple gradations, so it has not been put to practical use.

く問題点を解決する為の手段〉本発明は、前記従来の問題点に鑑みなされたもので、印
刷信号により制御して印刷用紙に印刷するインクジェッ
ト印刷装置における階調表現方法において、適量範囲内
のインク液滴をノズルより吐出させるインク吐出信号を
階調度に応じた個数だけ連続的に出力するインク吐出駆
動信号により、ノズルからのインク液滴の吐出を制御し
、所定のドツト位置に階調度に応じた量のインクを吐出
するようにしたことを要旨とする階調表現方法を提供し
、以って従来の問題点を一挙に解消することを目的とす
るものである。Means for Solving the Problems> The present invention has been made in view of the above-mentioned conventional problems, and is a gradation expression method in an inkjet printing device that prints on printing paper under control using a print signal. An ink ejection drive signal that continuously outputs an ink ejection signal for ejecting ink droplets from the nozzle in a number corresponding to the gradation level controls the ejection of ink droplets from the nozzle, and ejects the ink droplets at a predetermined position with the gradation level. The object of the present invention is to provide a gradation expression method that ejects an amount of ink according to the amount of ink, thereby solving the problems of the conventional methods at once.

〈実施例〉以下、本発明の一実施例を詳説する。<Example>Hereinafter, one embodiment of the present invention will be explained in detail.

第１図（ａ）〜（ｄ１図はそれぞれ階調度１〜４の場合
のインク液滴の付着位置を示している。同図から明らか
なように、ノズルよりインク液滴が安定に吐出する適量
範囲内の同一量のインク液滴が、ノズルよりインク液滴
が安定に吐出するくり回し周波数で階調度に応じた回数
だけ連続的にノズルから吐出される。換言すると、階調
度に対応した量のインクが階調度に応じた回数に等分さ
れて吐出される。この場合、単位面積当りのインク付着
個所は一定（実施例では６個所）とするが、ヘッドの印
字方向（横方向）への移動によって、連続的に吐出され
たインク液滴は僅かなずれで付着される。Figures 1(a) to (d1) show the adhesion positions of ink droplets for gradation levels 1 to 4, respectively.As is clear from the figure, the appropriate amount of ink droplets to be stably ejected from the nozzle. The same amount of ink droplets within the range are continuously ejected from the nozzle the number of times corresponding to the gradation level at a rotation frequency that allows ink droplets to be stably ejected from the nozzle.In other words, the amount corresponding to the gradation level The ink is ejected in equal parts a number of times according to the gradation level.In this case, the ink adhesion locations per unit area are fixed (six locations in the example), but the ink is ejected in the printing direction (horizontal direction) of the head. Due to the movement of the ink droplets, continuously ejected ink droplets are deposited with slight deviations.

第１図に示すように印刷用紙に付着されたインク液滴は
、用紙に染み込んで紙面に拡がり、第２図（ａ）〜（ｄ
）図に示すように、付着されたインク量に応じた大きさ
のドツトとなる。つまり階調度１〜４に応じた大きさの
ドツトとなる。従って、前述の■の従来方法と略々間等
の良好な階調リニアリティとなり、自然な階調表現とな
る。１回当りのインク液滴の吐出量は、例えば前述の■
の従来方法の場合と同程度で良いから、ノズルやインク
液滴の安定性の点に問題はな（、容易に多階調表現でき
る。As shown in Figure 1, the ink droplets attached to the printing paper soak into the paper and spread over the paper surface.
) As shown in the figure, the size of the dot corresponds to the amount of ink deposited. In other words, the dots have sizes corresponding to the gradations 1 to 4. Therefore, good gradation linearity is achieved, which is approximately on par with the conventional method (2) mentioned above, and natural gradation expression is achieved. The amount of ink droplets ejected per time is, for example, the above-mentioned
Since it is the same level as in the conventional method, there is no problem with the stability of the nozzle or ink droplets (and multi-gradation can be easily expressed).

次に、前記方法に用いる装置の一例を示した第３図にお
いて、ホストコンピュータからの印刷用データ信号が外
部インターフェイス１０を介してデータバッファ１）に
順次取り込まれ、このデータバッファ１）に例えば１頁
分の印刷データが記憶される。この印刷データに基づき
コントローラ１２が駆動して、ヘッドの移動に同期して
階調信号発生回路１３及び階間印刷タイミング発生回路
１４を制御する。そして、階調信号発生回路１３からは
、コントローラ１２の開−信号に基づくインク吐出信号
がタイミング発生回路１４からのクロック信号で出力さ
れ、インク吐出駆動回路１５によりノズルからインク液
滴を吐出する信号となり、ノズルを駆動してインクを吐
出する。即ち、階調度１．２．３．４の各場合に、それ
ぞれ第４図（ａ）、　（ｂ）、　（Ｃ１，（ｄ）図に示
すような階調度に応じた個数のインク吐出信号が連続的
に出力するインク吐出駆動信号により、ノズルに高電圧
を印加し、インク液滴がノズルから吐出される。Next, in FIG. 3 showing an example of the apparatus used in the above method, print data signals from the host computer are sequentially taken in to the data buffer 1) via the external interface 10, and the data buffer 1) is filled with, for example, Print data for pages is stored. The controller 12 is driven based on this print data and controls the gradation signal generation circuit 13 and the interlevel print timing generation circuit 14 in synchronization with the movement of the head. Then, the gradation signal generation circuit 13 outputs an ink ejection signal based on the open signal of the controller 12 in response to the clock signal from the timing generation circuit 14, and the ink ejection drive circuit 15 outputs a signal for ejecting ink droplets from the nozzle. The nozzle is driven to eject ink. That is, for each gradation level of 1, 2, 3, or 4, the number of ink ejection signals corresponding to the gradation level is as shown in FIGS. 4(a), (b), (C1, and (d)). A high voltage is applied to the nozzle by continuously outputting an ink ejection drive signal, and ink droplets are ejected from the nozzle.

〈発明の作用効果〉以上説明したように、本発明のインクジェット印刷装置
の階調表現方法によると、階調度に応じたインク量を等
分し、この一定量のインク液滴を階調度に応じた回数だ
け連続的に吐出させ、このインクの印刷用紙への染み込
みによってドツトを階調に応じた大きさとするようにし
たので、単位面積当りのドツトの数及び配置を一定とす
ることができ、ドツト密度が高くならないからヘッドの
走行スピードを上げる必要がなく、インクタンク内の液
揺れやドライブモータの大型化といった間題を解消する
ことができる。又、ドツトの数及び配置が一定であるか
ら、階調リニアリティが極めて良好となる。更に、階調
度に応したインク量を等分して数回に分けて連続的に吐
出させる為、多階調の表現を行なう場合にも、ノズルか
らの吐出インク量が常に一定となり、ノズルや吐出イン
ク液滴の安定性を確保することができ、容易に多階・調
表現できる大きな利点がある。<Operations and Effects of the Invention> As explained above, according to the gradation expression method of the inkjet printing apparatus of the present invention, the amount of ink is divided into equal parts according to the gradation level, and this constant amount of ink droplets is distributed according to the gradation level. The ink is continuously ejected the same number of times, and the ink soaks into the printing paper to make the dots a size corresponding to the gradation, so the number and arrangement of dots per unit area can be kept constant. Since the dot density does not increase, there is no need to increase the running speed of the head, and problems such as liquid shaking in the ink tank and an increase in the size of the drive motor can be solved. Furthermore, since the number and arrangement of dots are constant, gradation linearity is extremely good. Furthermore, since the amount of ink corresponding to the gradation is divided into equal parts and ejected continuously several times, even when expressing multiple gradations, the amount of ink ejected from the nozzle is always constant, and the nozzle and It has the great advantage of being able to ensure the stability of ejected ink droplets and easily expressing multiple gradations and tones.

【図面の簡単な説明】[Brief explanation of drawings]

第１図（ａ）〜（ｄ）図はそれぞれ本発明のインクジェ
ット印刷装置の階調表現方法の一実施例に係る階調度１
〜４の場合のインク液滴の付着位置の説明図、第２図（
ａｌ〜（ｄ１図はそれぞれ第１図（ａ）〜（ｄ）図にお
けるドツトの大きさを示す説明図、第３図は本発明方法
の実施に係る装置のブロック図、第４図（ａ）〜（ｄ）
図はそれぞれ第３図の装置における階調度１〜４の場合
の出力信号の波形図、第５図（ａ）〜（ｄ）図はそれぞ
れ従来方法に係る階調度１〜４の場合のドツト配置の説
明図、第６図（ａ）〜（ｉ）図はそれぞれ従来方法に係
る階調度１〜９の場合のドツト配置の説明図である。FIGS. 1(a) to 1(d) each show gradation level 1 according to an embodiment of the gradation expression method of the inkjet printing apparatus of the present invention.
An explanatory diagram of the adhesion position of ink droplets in cases of ~4, Figure 2 (
al~(d1 Figures are explanatory diagrams showing the sizes of dots in Figures 1 (a) to (d), respectively, Figure 3 is a block diagram of an apparatus for implementing the method of the present invention, Figure 4 (a) ~(d)
The figures are waveform diagrams of output signals in the case of gradations 1 to 4 in the apparatus shown in Fig. 3, and the figures in Figs. and FIGS. 6(a) to 6(i) are explanatory diagrams of dot arrangement for gradations 1 to 9 according to the conventional method, respectively.

Claims (1)

Translated fromJapanese

【特許請求の範囲】[Claims]（１）印刷信号により制御してインク液滴を印刷用紙に
飛翔させて印刷するインクジェット印刷装置における階
調表現方法において、適量範囲内の一定量のインク液滴
をノズルより吐出させるインク吐出信号を階調度に応じ
た個数だけ連続的に出力するインク吐出駆動信号により
、ノズルからのインク液滴の吐出を制御し、所定のドッ
ト位置に階調度に応じた量のインクを吐出するようにし
たことを特徴とするインクジェット印刷装置の階調表現
方法。(1) In a gradation expression method in an inkjet printer that prints by flying ink droplets onto printing paper under the control of a print signal, an ink ejection signal that causes a certain amount of ink droplets within an appropriate amount range to be ejected from a nozzle is used. The ejection of ink droplets from the nozzle is controlled by an ink ejection drive signal that continuously outputs the number of ink droplets corresponding to the gradation, and the amount of ink corresponding to the gradation is ejected to a predetermined dot position. A gradation expression method for an inkjet printing device characterized by: