JPS6236868B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color inkjet printing device that selectively ejects ink of each color from a plurality of ink ejection nozzles to perform color recording on recording paper.

Color inkjet printing devices are usually equipped with three inkjet heads, which selectively eject cyan, magenta, and yellow inks to record various colors on recording paper, either as a single color or as a mixture of these inks. do.

In order to record various colors in this way, it is necessary to apply ink dots of each color to the same point or near the same point on the recording paper using each jet nozzle. Therefore, in the past, each injection nozzle was directed to the same point on the recording paper, or a delay circuit was inserted in each printing signal line, thereby correcting the dot misalignment due to the difference in the arrangement position of the injection nozzles. The ink droplets from each jet nozzle are superimposed to create various colors by mixing colors.

In such a color inkjet printing device, the larger the difference between the maximum diameter and the minimum diameter of the ink droplets ejected by each ejection nozzle, the better the color expression. Therefore, it is preferable to drive the ink-on-demand type ink jet head with an analog printing signal to change the ink droplet diameter in accordance with the analog signal level to express halftones. However, in the case of black expression, for example, yellow, magenta, and cyan ink droplets are ejected with maximum particle size, which causes ink oversaturation on the recording paper, causing excessive ink smearing, running, or Excessive splashing and splashing occurs due to ink collision, resulting in deterioration of recorded images and deterioration of jetting function due to contamination of the ink jet head. This phenomenon is not limited to black expression;
This problem also occurs when the ink particle size is increased and ink of two or more colors is ejected to the same point.

SUMMARY OF THE INVENTION An object of the present invention is to reduce oversaturation, splashing, or splashing of ink on a recording paper, which occurs during overlapping printing using ink droplets of each color from a plurality of ink ejection nozzles.

In order to achieve the above object, the present invention generally comprises:
The level detecting means detects whether the level of the input color component printing signal is above or below a set level, and when the level is above the set level, the level is suppressed more than when it is below the set level and the inkjet energizing means is energized. composition.

Specifically, the first invention of the present application is an adding means for adding the level of an input color component printing signal; and adjusting the level of the input color component printing signal to a level inversely corresponding to the level added by the adding means. level adjusting means for applying the level to the inkjet head energizing means; level detecting means for detecting whether the level of the input color component printing signal is above or below the set level; gate means for changing the level of the signal applied from the addition means to the level adjustment means to the base level when detecting the addition means;

According to this, when the input color component printing signal is equal to or higher than the set level, the input color component printing signal is set to a level that corresponds inversely to the added value of the input color component printing signal (total ink amount instruction value to be recorded at one dot position). The printing signal is adjusted and applied to the inkjet head energizing means, and the larger the added value, the larger the recording ink amount suppression rate for each color becomes. It becomes a record. This reduces the amount of recording ink when the input color component printing signal level is high and the sum of these signals is large, such as when recording black, to reduce oversaturation, splashing, or splashing of the ink on the recording paper.

The second invention of the present application provides an adding means; a gate means for supplying each of a plurality of input color component printing signals to the adding means; a level of the input color component printing signal corresponding in order to a level added by the adding means; A level adjusting means adjusts the level and applies it to the inkjet head energizing means; and detects whether the level of each input color component printing signal is higher than a set level, and when detected above the set level, a gate means A level detecting means is provided for instructing to stop supplying the input color component printing signal having the set level or higher to the adding means.

According to this, when the input color component printing signal is equal to or higher than the set level, the input color component printing signal to the addition means is cut off, the output level of the addition means is lowered, and the input color The component printing signals are adjusted to a low level and applied to the ink jet head urging means, and the amount of recording ink for each color is suppressed. This reduces the amount of recording ink when the input color component printing signal level is high, such as when recording black, thereby preventing oversaturation of ink on the recording paper.
This has a great effect on reducing splashes or splashes.

When the level of the input color component printing signal is less than the set level (small diameter recording instruction), the input color component printing signal is given to the adding means, and the addition level is given to the adjusting means, so that the input color component printing signal is is adjusted to a high level corresponding in order to the addition level and applied to the ink jet head urging means, resulting in printing with a high gradation degree of halftone expression without suppressing the amount of printing ink. This has a great effect on sufficiently expressing halftones when the input color component printing signal level is low, such as when recording relatively bright colors other than black.

Other objects and features of the present invention will become apparent from the following description with reference to the drawings.

FIG. 1 shows an embodiment of the first invention of the present application. In this embodiment, the level adjustment circuit 1 has three
It consists of a set of amplifier circuits. Each amplifier circuit is connected to a cyan printing signal C line, a magenta M printing signal line, and a yellow printing signal Y line, and includes an amplifier 1 ₁ , a feedback resistor 1 ₂ , and a voltage-controlled variable resistance element, respectively. (for example
It consists of ₁₃ MOS type FETs. In these amplifier circuits, the feedback resistance value of the amplifier 1 ₁ is the resistance value of the feedback resistor 1 ₂ and the voltage controlled variable resistance element 1 ₃
It is determined by the resistance value of _The level of each imprint signal C, M, and Y is amplified by the amplifier ₁₁ and applied to the high voltage pulse modulators ₅₁ , ₅₂ , and ₅₃ . By changing the resistance value between the source and drain in accordance with the applied voltage, the amplification factor changes in accordance with the gate _{voltage .} The signal level is adjusted. That is, the higher the output level of the adding circuit 2, the lower the resistance value of the voltage controlled variable resistance element ₁₃ , and the lower the resistance value of the voltage controlled variable resistance element ₁₃ , the lower the amplification factor of the amplifier ₁₁ . That is, the amplifier ₁₁ generates an output at a level inversely corresponding to the output level of the adder circuit 2.

The adder circuit 2 includes resistors 2 ₂ , 2 ₃ and 2 whose ends are connected to the lines of each printing signal C, M and Y.
₄ , an amplifier 2 ₁ and a feedback resistor 2 ₅ , and an amplifier 2 ₆ and a feedback resistor 2 ₇ . The other end of resistors ₂₂ to ₂₄ is the - (minus) of amplifier ₂₁ .
They are commonly connected to the input terminal, and one end of the resistor ₂₅ is connected to the input terminal, and the other end is connected to the output terminal of the amplifier ₂₁ . Therefore, at the output terminal of the amplifier ₂₁ , a voltage of negative polarity appears at the level (absolute value) that is the sum of the signal levels (positive) of the printing signals C, M, and Y. This is inverted and amplified by the amplifier ₂₆ and converted to positive polarity. In other words, considering the polarity, the signal levels (positive) of the printing signals C, M, and Y
A signal (of positive _polarity ) obtained by adding .

The level detection circuit 3 includes comparators 3 ₁ , 3 ₂ and 3 that compare the level of each printing signal C, M and Y with a printable signal level (set level) Vref.
₃ , AND gate circuits 3 ₄ , 3 ₅ and 3 ₆ to which the outputs of two of the three comparators are input, and an OR gate circuit 3 ₇ . This level detection circuit 3 allows two or more of the printing signals C, M and Y to reach the set level at the same time through the wiring shown in the diagram.
When it is equal to or higher than Vref, a high level "1" signal is output from the OR gate circuit ₃₇ .

The gate circuit 4 is composed of a switching element ₄₁ for forcing the output of the adder circuit 2 to the base level. The switching element 4 ₁ is non-conductive when there is a high level "1" signal, but conductive when there is a low level "0" signal, and the amplifier 2 ₆
Block input to. That is, the level applied from the adder circuit 2 to the level adjustment circuit 1 is changed to the equipment ground level, which is the base level.

In this state, the resistance value of the voltage-controlled variable resistance element _1-3 of the level adjustment circuit 1 is the maximum in the setting range, and the resistance value of the voltage-controlled variable resistance element 1-3 of the level adjustment circuit 1 is the maximum of the setting range, and the resistance value of the amplifier circuit consisting of the amplifier _1-1 , the resistor _1-2 , and the voltage-controlled variable resistance element _1-3 is The amplification factor becomes the maximum of the usage setting range.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

Now, if only one of the color printing signals C, M, and Y is higher than the set level, the level detection circuit 3 outputs any of the AND gate circuits ₃₄ to ₃₆ (high level "1"). ), so it does not produce an output signal (high level "1"). Therefore, the switching element ₄₁ of the gate circuit 4 is in a conductive state, bringing the output of the adder circuit 2 to the base level. Therefore, the amplification factor of each amplifier circuit ₁₁ of the level adjustment circuit 1 is maximum, and the printing signal is applied to the high voltage pulse modulator ₅₁ , ₅₂ or ₅₃ at the highest level.
This state is similar to conventional printing energization, and printing is recorded with a density corresponding to the printing signal level.

Next, when two or more of the color component printing signals C, M, and Y have a signal level equal to or higher than the printing level, the level detection circuit 3 generates an output signal "1", and the switching element 4 ₁ of the gate circuit 4 becomes non-conductive,
The output of the adding circuit 2, which adds the levels of the color component printing signals C, M, and Y, is the output of the voltage-controlled variable resistance element 1.
₃ , the resistance value of the voltage controlled variable resistance element ₁₃ decreases in response to this voltage level, and the amplification factor of the amplifier circuit ₁₁ decreases. As a result, the level of the printing signals applied to the high-voltage pulse modulators 5 ₁ to 5 ₃ decreases, that is, the color component printing signals C, M,
If the added value of the level of Y is high, the high voltage pulse modulator 5
The applied signal levels applied to _the high voltage pulse modulators 5 1 to 5 ₃ are adjusted in an inverse relationship that the applied signal levels applied to the high voltage pulse modulators 5 ₁ to 5 ₃ are low, and two or more of the applied signals are set. When the ink droplets are above the level, the particle size of the ink droplets ejected from each ink jet head 6 ₁ to 6 ₃ is smaller than in the case of conventional recording without adjustment.
becomes smaller. This particle size is controlled via the amplifier circuit ₁₁ and the amplifier circuit ₂₆ in inverse correspondence to the addition level of the printing signal. In other words, when the number of inkjet heads activated for printing at the same time is two or more, the levels of the input color printing signals C, M, and Y are added depending on whether the number is two or three. According to the value, m ₁ + m ₂ <mc for two energizing heads, and mc for three energizing heads.
m ₁ + m ₂ + m ₃ <mc (where, m ₁ , m ₂ , m ₃ are the weights of ink droplets ejected from each ink jet head, and mc is the weight of ink droplets ejected from each ink jet head, and mc is the weight of ink droplets that occur on the recording paper due to ink flow, excessive splashing, splashing, etc.) The resistance value and amplification factor of each circuit are set so that the level of the color component printing signal is adjusted and applied to the high-voltage pulse modulators ₅₁ to ₅₃ so that the level of the color component printing signal is not a critical value. Therefore, ink flow, excessive splashing, splashing, etc. on the recording paper are reduced.

FIG. 2 shows an embodiment of the second invention of the present application. In the embodiment shown in FIG. 1, the level detection circuit 3 makes the switching element ₄₁ of the gate circuit 4 non-conductive and outputs the output of the adder circuit 2 only when two or more color component printing signals are equal to or higher than the set level. Although this is applied to the level adjustment circuit 1 to lower the printing signal level, the level of each color component printing signal may always be adjusted by the sum of the color component printing signal levels. When doing this, for example, even if only one color print signal is above the set level, the added level of the other two color component print signals below the set level will affect the level adjustment.

Therefore, in the embodiment shown in FIG. 2, the gate circuit 4 is connected before the adder circuit 2, and each of the switching elements ₄₄ to ₄₆ of the gate circuit 4 is connected to the comparator _31.
~3 When the output of ₃ is "1" (high level), it is non-conductive (cut off), and when it is "0" (low level), it is conductive. In this embodiment, the configuration of the level adjustment circuit 1 is the same as the embodiment shown in FIG. 1, so the lower the level of the output of the adder circuit 2, the higher the amplification factor. However, since the addition circuit 2 of FIG. 2 generates the addition level of the color component printing signal with negative polarity, the higher the addition level (absolute value), the lower the output level (in the negative direction). Expressing this in terms of the absolute value of the addition level, in this embodiment, the higher the addition level (positive value = absolute value) of the color printing component signal level (positive value = absolute value), the higher the level adjustment circuit 1
The amplification factor is high, and the level adjustment circuit 1 adjusts the color component printing signal to a level corresponding in order to the level (positive value=absolute value) added by the addition circuit 2.

Therefore, from this point of view only, the higher the color component printing signal level, the larger the amount of recording ink. However, in this embodiment, when the printing signal C is equal to or higher than the set level Vref, Comparator 3 ₁
Since the output of the switch becomes "1" and the switching element ₄₄ is cut off, the printing signal C is not added to the adder circuit 2, so the addition level of the adder circuit 2 (positive value = absolute value)
decreases (the level increases because the output signal level is of negative polarity), and the amplification factor of the level adjustment circuit 1 decreases by an amount equivalent to the level of the imprint signal C, compared to when the imprint signal C is added to the adder circuit 2. , the amount of recording ink is suppressed. The same applies to printing signals M and Y.

Therefore, when all of the printing signals C, M, and Y are above the set level, the addition level (positive value = absolute value) of the addition circuit 2 is the lowest (the output signal level is the highest because it has negative polarity). , the amplification factor of the level adjustment circuit 1 becomes the lowest, and the amount of recording ink is suppressed the most.

In this embodiment, roughly speaking, the amplification factor of the level adjustment circuit 1 changes in accordance with the printing signal level, and as the printing signal level increases, the amplification factor increases. When the level exceeds the set level, the input of the printing signal to the adding circuit 2 is cut off, so that the amplification factor decreases and the rate of increase in the amplification factor decreases. As the number of printing signals equal to or higher than the set level increases, the decrease in the amplification factor and the decrease in the increase rate increase. That is, in this embodiment, the amplification factor of the level adjustment circuit 1 is increased in accordance with the print signal level, and the recording density (dot diameter) with respect to the print signal is adjusted.
The gradation is increased, but the amplification factor is lowered each time one printing signal level exceeds the set level, and the rate of increase in the amplification factor is reduced to suppress the amount of recording ink for each color when recording large-diameter dots overlappingly. I try to do that. In other words, depending on how many of the printing signals C, M, and Y are above the set level, the high voltage pulse modulators 5 ₁ to 5 ₃ are inversely corresponding to the number above the set level.
The level of the imprint signal applied to is adjusted. Therefore, in this embodiment as well, ink flow, excessive splashing, splashing, etc. are reduced.

As explained above, in the first invention of the present application, when the input color component printing signal is equal to or higher than the set level, the addition value (1
The input color component printing signal is adjusted to a level inversely corresponding to the total ink amount instruction value recorded at the dot position and is applied to the inkjet head urging means,
The larger the added value, the greater the recording ink amount suppression rate for each color, resulting in recording with a smaller ink amount than the ink amount instructed by the input color component printing signal. This reduces the amount of recording ink when the input color component printing signal level is high and the sum of these signals is large, such as when recording black, to reduce oversaturation, splashing, or splashing of the ink on the recording paper.

According to the second invention of the present application, when the input color component printing signal is equal to or higher than the set level, the input color component printing signal to the adding means is cut off, and the added level becomes lower, and the corresponding processing is performed accordingly. Then, the input color component printing signal is adjusted to a low level and applied to the ink jet head urging means, and the amount of recording ink for each color is suppressed. This reduces the amount of recording ink when the input color component printing signal level is high, such as when recording black, and has a great effect in reducing oversaturation, splashing, or splashing of ink on the recording paper.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the first invention of the present application. FIG. 2 is a block diagram showing the configuration of an embodiment of the second invention of the present application. 1: Level adjustment circuit (level adjustment means), 2:
Addition circuit (addition means), 3: Level detection circuit (level detection means), 4: Gate circuit (gate means),
5 ₁ to 5 ₃ : high voltage pulse modulator (ink jet head energizing means), 6 ₁ to 6 ₃ : ink jet head.

Claims (1)

[Claims] 1. In a color inkjet recording device that performs color recording by energizing the inkjet head corresponding to each color with a plurality of color component printing signals: Addition of adding the levels of input color component printing signals Means: Level adjusting means for adjusting the level of the input color component printing signal to a level inversely corresponding to the level added by the adding means and applying it to the inkjet head energizing means; The level of the input color component printing signal is set to the set level. Level detecting means for detecting whether the level is above or below the set level; and gate means for changing the level of the signal applied from the adding means to the level adjusting means to the base level when the level detecting means detects that the level is below the set level; A color inkjet printing device comprising: 2. In a color inkjet recording device that performs color recording by energizing inkjet heads corresponding to each color with a plurality of color component printing signals: Adding means for adding the levels of a plurality of input color component printing signals; Input color Level adjusting means for adjusting the level of the component printing signal to a level corresponding in order to the level added by the adding means and applying it to the ink jet head energizing means; when each level of the input color component printing signal is equal to or higher than the set level and, when the level detection means detects that the level is equal to or higher than the set level, gate means for stopping the supply of the input color component printing signal of the verification level or higher to the addition means. A color inkjet printing device characterized by: 3. The gate means includes a plurality of gate elements, one of which is inserted between each of the input color component printing signals and the addition means; the level detection means is configured such that each of the input color component printing signals has a set level. or above, and when it is detected that the input color printing signal is equal to or higher than the set level, a gate element inserted between the input color printing signal equal to or higher than the set level and the adding means is shut off; Color inkjet printing device as described in .