JP2007223263A - Picture drawing device, and rationalizing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a picture drawing device which can suppress the decrease of a picture quality while corresponding to driving signals of a plurality of systems, and to provide a rationalizing method for the picture drawing device. <P>SOLUTION: A driving signal forming circuit 75 is equipped with a first signal forming section 60A and a second signal forming section 60B. A CPU 72 forms digital data (designing data) which specifies an electric potential difference and a temporal component of each subsidiary pulse which are constituent elements of the driving signals based on function information and the detected value of an environmental temperature being housed in a memory 73. The first and second signal forming sections 60A and 60B form the driving signals from the designing data. In this case, the designing data is corrected under a condition which has been optimized for each individual in advance in such a manner that an output difference in the driving signals between the first and second signal forming sections 60A and 60B may substantially be compensated. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a droplet discharge type drawing apparatus that performs drawing by scanning a head, and a method for optimizing operating conditions in the drawing apparatus.

  2. Description of the Related Art Conventionally, as a drawing apparatus of a droplet discharge method (inkjet method), a drawing device that draws by periodically ejecting ink droplets from a head having nozzles in a predetermined arrangement and scanning the head is known. It has been. Ink droplets are ejected by supplying an electric signal (driving signal) to driving means such as a piezoelectric element provided in the vicinity of the nozzle (for example, Patent Document 1). The drive signal according to this document is generated by a drive signal generation circuit including a digital / analog (D / A) converter and an amplifier circuit based on predetermined digital data.

Japanese Patent Laid-Open No. 11-20203

  By the way, due to demands such as improvement in the degree of freedom of gradation control and suppression of heat generation of the drive signal generation circuit, there has been proposed a drawing apparatus that selectively supplies a plurality of drive signals to the drive means ( For example, Japanese Patent Application No. 2005-327782). In such a drawing apparatus, due to differences in internal hardware such as a D / A converter provided for each system, a difference occurs in the output value of the drive signal between the systems, and the amount of ejected ink droplets In addition, the speed may be non-uniform and image quality may be degraded.

  SUMMARY An advantage of some aspects of the invention is that it provides a drawing apparatus capable of suppressing deterioration in image quality while supporting a plurality of drive signals and a method for optimizing the drawing apparatus. It is said.

  The present invention generates a head having nozzles in a predetermined arrangement, discharge driving means for discharging droplets from the nozzles, and a drive signal for driving the discharge driving means based on predetermined digital data Two or more signal generation means, an ejection control means for supplying an electrical drive signal to the ejection drive means under the scanning of the head to eject droplets from the nozzle, and the two or more signal generation means Output compensation means for substantially compensating for the output difference of the drive signal between the two.

  According to the drawing apparatus of the present invention, since the output difference between the one and the other signal generating means is substantially compensated by the output compensating means, the droplets can be obtained regardless of the generation source of the drive signal related to the ejection of the droplets. The amount, speed, etc. of the image are made uniform, and image quality deterioration is suppressed.

Further preferably, in the drawing apparatus, the output compensation unit is a unit that corrects the digital data under a condition based on a value of a predetermined parameter, and includes a storage unit that stores an appropriate value of the predetermined parameter. It is characterized by providing.
According to the drawing apparatus of the present invention, the means for detecting the absolute value of the output value and the output value are corrected by correcting the digital data based on the appropriate value of the predetermined parameter stored in the storage means. Even if a hardware mechanism is not added, the output difference of the drive signal between the signal generation means can be compensated with a relatively simple configuration.

Further preferably, in the drawing apparatus for drawing a test pattern for determining an appropriate value of the predetermined parameter, the test pattern is the drive signal generated by each of the first and second signal generation means. And having a first unit pattern and a second unit pattern which are respectively drawn to form a pair by the drive signals generated based on the digital data which are identical to each other when the correction is not performed. And
According to the drawing device of the present invention, the alignment between the paired first and second unit patterns reflects the difference in the velocity of the droplets corresponding to each unit pattern. The substantial output difference of the drive signal between the first and second signal generating means can be estimated. Thus, an appropriate value for the predetermined parameter can be determined by a simple method.

Further preferably, in the drawing apparatus for drawing the test pattern having a plurality of pairs, the output compensation means may perform the correction by differentiating the values of the predetermined parameters when drawing the plurality of pairs, respectively. It is characterized by performing.
According to the drawing apparatus of the present invention, a plurality of pairs drawn with different values of predetermined parameters are drawn at a time, so the alignment between unit patterns in each pair is compared and the most appropriate pair is selected. Thus, the value of the predetermined parameter corresponding to the selected pair can be determined easily and quickly as the appropriate value.

Also preferably, in the drawing apparatus for drawing the test pattern having the plurality of pairs, the value of the predetermined parameter corresponding to the pair is drawn as text in the vicinity of the plurality of pairs. And
According to the drawing device of the present invention, since the value of the predetermined parameter corresponding to the vicinity of the pair is displayed, the appropriate value of the predetermined parameter can be determined easily and quickly.

Preferably, in the drawing apparatus for drawing the test pattern, the first unit pattern and the second unit pattern are drawn by scanning in the same direction.
According to the drawing apparatus of the present invention, since it is not affected by the misalignment due to the difference in the scanning direction, the output difference of the drive signal between the corresponding signal generating means can be accurately estimated from the alignment between the unit patterns. Can do.

  The present invention generates a head having nozzles in a predetermined arrangement, discharge driving means for discharging droplets from the nozzles, and a drive signal for driving the discharge driving means based on predetermined digital data Two or more signal generating means for discharging, an ejection control means for supplying an electrical drive signal to the ejection driving means under the scanning of the head to eject droplets from the nozzles, and a predetermined parameter value. Output compensation means for substantially compensating for an output difference between the plurality of signal generation means by correcting the digital data under a predetermined condition, and storage means for storing an appropriate value of the predetermined parameter. In the drawing apparatus, an optimization method for optimizing the value of the predetermined parameter, wherein the drive signals generated by the first and second signal generation units, respectively. A drawing step of drawing the first and second unit patterns that are paired with each other by the drive signal generated based on the digital data that are identical to each other when the correction is not performed; And an estimation step for estimating an appropriate value of the predetermined parameter by observing the alignment between the second unit patterns, and an appropriate value of the predetermined parameter in the storage unit based on an estimation result in the estimation step. And a setting step for storing.

  According to the optimization method of the present invention, the alignment between the paired first and second unit patterns reflects the difference in the velocity of the droplets corresponding to each unit pattern. It is possible to optimize the correction parameter by estimating a substantial output difference between the drive signals corresponding to each unit pattern. In this case, the drawing of the unit pattern for optimization can be performed efficiently in a general pre-shipment inspection process without using a special device.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings.
The embodiment described below is a preferred specific example of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, the present invention is not limited to these forms. In the drawings referred to in the following description, the vertical and horizontal scales of members or portions may be represented differently from actual ones for convenience of illustration.

(About the mechanical structure of the drawing device)
First, the mechanical configuration of the drawing apparatus will be described with reference to FIG. 1, FIG. 2, and FIG.
FIG. 1 is a perspective view showing the overall configuration of the drawing apparatus. FIG. 2 is a perspective view showing an external configuration of the head. FIG. 3 is a cross-sectional view of the main part showing the internal structure around the nozzle of the head.

  In FIG. 1, a printer 1 as a drawing device includes a guide frame 3 formed of a steel plate or the like, a transport roller 4 for transporting paper 2, and a head having minute nozzles 20 (see FIG. 2) on a nozzle surface 10a. 10 and a maintenance unit 5 for performing nozzle maintenance of the head 10. The head 10 is mounted on the carriage 6 and is reciprocated (scanned) along the guide rod 8 by driving the drive belt 9. That is, the carriage 6, the guide rod 8, and the drive belt 9 constitute the scanning means of the present invention. The guide frame 3 forms the basis of the entire apparatus by its rigidity and weight, and also functions as an electrical ground.

  The carriage 6 is mounted with ink cartridges 7a to 7d that respectively store four colors of ink (for example, magenta, cyan, and yellow black inks) as liquids, and the head 10 receives inks of these colors. Supplied. Then, ink droplets are ejected from the nozzle surface 10 a in synchronization with the scanning of the carriage 6 and the conveyance of the paper 2, and an image is formed on the paper 2.

  The maintenance unit 5 includes a cap 11 that can be brought into close contact with the nozzle surface 10a of the head 10 and a wiper blade 12 that is a plate-like member formed of rubber or the like. The cap 11 serves not only to protect the nozzle 20 (see FIG. 2) from dust and drying, but also during a so-called recovery operation that sucks ink from the nozzle 20 (see FIG. 2) to remove foreign matter and the like. Used. The wiper blade 12 is used for wiping off ink adhering to the nozzle surface 10a.

  2 and 3, the nozzles 20 provided on the nozzle surface 10 a constitute four nozzle rows 21 arranged in a line perpendicular to the scanning direction. Different types (colors) of ink are ejected from the nozzles 20 of each nozzle row 21.

  The head 10 includes a cavity 22 that communicates with each of the nozzles 20, and a reservoir 23 that is a common chamber for each nozzle row 21 that communicates with each cavity 22. The canopy portion 24 of the cavity 22 can be moved by the flexible film 25, and ink droplets are ejected by driving the piezoelectric element 26 serving as ejection driving means joined to the canopy portion 24. More specifically, the ink droplet ejection control is performed by an electric drive signal supplied to the piezoelectric element 26.

  The drive signal is composed of periodic pulses synchronized with the scanning of the head 10, and thereby marking on the paper 2 with ink droplets at a predetermined interval (resolution). The same drive signal is supplied to the piezoelectric elements 26 of the nozzle rows 21, but the nozzle rows 21 are arranged so that the marking positions (ink droplet landing positions) do not shift between the nozzle rows 21. The distance d is an integer multiple of the resolution.

  The specific configuration of the head 10 such as the nozzle arrangement and the driving method is not limited to the above-described embodiment. For example, the nozzle row 21 may be inclined with respect to the scanning direction. Further, as a driving method, a so-called thermal method in which bubbles are generated in the cavity by driving the heating element to discharge the ink inside can be adopted.

(Electric configuration of the drawing device and discharge control)
Next, with reference to FIGS. 4 and 5, the electrical configuration of the drawing apparatus and the discharge control will be described.
FIG. 4 is a block diagram illustrating an electrical configuration of the drawing apparatus. FIG. 5 is a timing diagram showing a drive signal, a head control signal, and a switch signal.

  The printer 1 includes an external interface (I / F) 71, a CPU 72, a memory 73 including a RAM and a ROM (including an EEPROM), a transmission circuit 74, a drive signal generation circuit 75, and an internal I / F 76 connected to each other via an internal bus. A print controller 70 is provided. The print controller 70 is connected to the host PC 200 via the external I / F 71, and is connected to the head controller 80, the scanning drive scanning motor 13, and the paper conveyance driving conveyance motor 14 via the internal I / F 76. Yes.

  The print controller 70 generates two types of drive signals, a first drive signal (COM_A) and a second drive signal (COM_B). Further, the print controller 70 generates various head control signals (CLK, SI, LAT, CH_A, CH_B) based on the drawing pattern data (raster data) in the bitmap format received from the host PC 200. The head controller 80 that receives the drive signal and the head control signal controls the ejection of the head 10. That is, the print controller 70 and the head control unit 80 constitute an ejection control unit of the present invention.

  The drive signal and the head control signal are transmitted in synchronization with a timing signal (PTS) transmitted in conjunction with the scanning position of the head 10. In this case, the print controller 70 can change the offset time of the transmission timing (drive timing) with respect to the timing signal (PTS), thereby adjusting the marking position in the scanning direction. Can do.

  The head controller 80 includes first and second shift registers (SR) 81A and 81B, first and second latch circuits 82A and 82B, a decoder 83, and first and second switches 85A and 85B. Corresponding to each piezoelectric element 26 of the nozzle. The head control unit 80 includes a control logic 84.

  A first drive signal (COM_A) and a second drive signal (COM_B) are supplied to the piezoelectric element 26 via the first switch 85A and the second switch 85B, respectively. Here, the first drive signal (COM_A) has pulses PS1A, PS2A, and PS3A, and the second drive signal (COM_B) has pulses PS1B, PS2B, and PS3B within the recording period T. The pulses are connected at a predetermined intermediate potential.

  The pulses PS1A, PS3A, PS2B, and PS3B are the same pulse, and are supplied to the piezoelectric element 26 to eject the same amount of ink droplets (hereinafter referred to as normal dots). Further, the pulse PS1B is supplied to the piezoelectric element 26, thereby ejecting a smaller amount of ink droplets (hereinafter referred to as micro dots) than the normal dots. Further, the pulse PS2A is supplied to the piezoelectric element 26 and generates pressure vibration (fine vibration) in the cavity 22 (see FIG. 3) to the extent that ink droplets are not ejected. It has a role which suppresses the drying by stirring.

  The print controller 70 decodes the drawing pattern data and generates gradation data for each nozzle. This gradation data is composed of 2 bits, and is expressed as (00), (01), (10), (11) in the following by combinations of upper bits and lower bits. The gradation data is converted into a serial signal for each lower bit and upper bit in nozzle row units, and transmitted to the first shift register 81A and the second shift register 81B as a data signal (SI).

  The gradation data transmitted to the first and second shift registers 81A and 81B are latched by the latch signal (LAT) at the start timing of the recording cycle by the first and second latch circuits 82A and 82B, respectively, and Entered.

  The control logic 84 receives the latch signal (LAT), the first change signal (CH_A), and the second change signal (CH_B) and generates switch signals q0 to q7. Here, the first change signal (CH_A) is a signal that defines the time division timing related to the supply of the first drive signal (COM_A). In the present embodiment, the first change signal (CH_A) is set so that the recording cycle T is divided into periods T1 to T3 corresponding to the pulses PS1 to PS3, respectively. The second change signal (CH_B) is a signal that defines time division timing related to the supply of the second drive signal (COM_B). In the present embodiment, the timing is exactly the same as that of the first change signal (CH_A), but the two do not necessarily have to match.

  The switch signals q0 to q7 generated by the control logic 84 are transmitted to the decoder 83. The decoder 83 selects one of the switch signals q0 to q3 according to the gradation data received from the latch circuits 82A and 82B and supplies the selected signal to the gate line of the first switch 85A. The decoder 83 selects one of the switch signals q4 to q7 according to the gradation data received from the latch circuits 82A and 82B and supplies the selected signal to the gate line of the second switch 85B. Specifically, the switch signals q0 and q4 for the gradation data (00), the switch signals q1 and q5 for the gradation data (01), and the switch signals q2 and q2 for the gradation data (10). As for q6, switch signals q3 and q7 are supplied to the first and second switches 85A and 85B for the gradation data (11), respectively.

  The switch signals q0 to q7 are digital signals that are divided into a low level and a high level in units of periods T1, T2, and T3. During the low level period, the switches 85A and 85B are in the OFF state and the high level. During the period, the switches 85A and 85B are turned on. Thus, the pulses PS1A, PS2A, PS3A to PS1B, PS2B, PS3B of the drive signals corresponding to the periods T1, T2, T3 are selectively supplied to the piezoelectric element 26. Needless to say, either the pulse of the first drive signal (COM_A) or the pulse of the second drive signal (COM_B) can be supplied to the piezoelectric element 26 in the same period.

  In the case of the present embodiment, for the gradation data (00), the pulse PS2A is supplied to the piezoelectric element 26. At this time, ink droplets are not ejected, but there is a slight vibration to suppress drying of the ink in the nozzles. appear. For the gradation data (01), the pulse PS1B is supplied to the piezoelectric element 26, and microdots are ejected (marked as small dots). For gradation data (10), pulses PS2B and PS3B are supplied to the piezoelectric element 26, and two normal dots are ejected (marked as medium dots). For gradation data (11), pulses PS1A, PS2B, PS3B are supplied to the piezoelectric element 26, and three normal dots are ejected (marked as large dots). As described above, the printer 1 according to this embodiment can perform gradation control of marking according to the size and number of ejected ink droplets.

  Note that the configuration of the drive signal and the selection of the configuration pulse based on the gradation data are not limited to the above-described mode. It is also possible to switch the configuration of the drive signal, head control signal, and switch signal in accordance with the drawing operation mode.

(About drive signal generation)
Next, details of generation of the drive signal will be described with reference to FIGS. 5, 6, and 7.
FIG. 6 is a block diagram illustrating a main configuration of a drawing apparatus related to generation of a drive signal. FIG. 7 is a configuration diagram of drive signals.

  In FIG. 6, the drive signal generation circuit 75 includes a first signal generation unit 60A as a first signal generation unit and a second signal generation unit 60B as a second signal generation unit. Here, the first signal generation unit 60A and the second signal generation unit 60B have the same configuration, and include digital / analog (D / A) converters 61A and 61B and amplification units 62A and 62B, respectively. . The print controller 70 receives a detection result from a thermistor 77 that measures the environmental temperature around the printer 1.

  The CPU 72 reads out the function information stored in the memory 73 and the parameters (drive voltage, TR, correction parameters) related to the function information, acquires the detection result of the environmental temperature from the thermistor 77, and performs necessary calculation operations. Then, predetermined digital data (hereinafter referred to as design data) is generated and transmitted to the drive signal generation circuit 75. The first and second signal generators 60A and 60B convert the input design data into analog signals by the D / A converters 61A and 61B, and amplify them by the amplifiers 62A and 62B. First and second drive signals (COM_A, COM_B) as shown in FIG.

  By the way, the state of each signal shown in FIG. 5 indicates the case of forward scanning, and in the case of backward scanning, the configuration (shape) of the first driving signal (COM_A) and the second driving signal (COM_B). ) Are interchanged, and the configurations of the switch signals q0 to q3 and the switch signals q4 to q7 are also interchanged. As described above, the configuration of the drive signal and the switch signal is switched between the forward scan and the backward scan because the first signal generation unit 60A and the second signal generation unit 60B are caused by the difference in the configuration of the drive signal. This is because the aim is to average the difference in calorific value.

  Here, the configuration of the drive signal will be described. The drive signal shown in FIG. 7 shows the configuration of the second drive signal (COM_B) in FIG. 5, and is composed of sub-pulses p1 to p21 for charging, voltage holding, and discharging, as shown. . The design data described above defines the components (coordinates) related to the potential and time of each of the subpulses p1 to p21.

  The potential difference and time components of the subpulses p1 to p21 can be expressed as a function (including a constant function) with the drive voltage as a parameter. Specifically, the potential difference between the sub-pulses p1, p3, p5, p7, and p9 constituting the pulse PS1B changes uniformly in proportion to the drive voltage Vh1B represented by the difference between the lowest potential and the highest potential of the pulse PS1B. Have been to. Similarly, the potential difference between the subpulses p11, p13, and p15 is proportional to the drive voltage Vh2B represented by the difference between the lowest potential and the highest potential of the pulse PS2B, and the potential difference between the subpulses p17, p19, and p21 is the lowest potential of the pulse PS3B. And uniformly change in proportion to the drive voltage Vh3B represented by the difference between the maximum potential and the maximum potential.

  Thus, by individually setting the magnitudes of the drive voltages Vh1B, Vh2B, and Vh3B according to the displacement characteristics of the piezoelectric element 26 (see FIG. 3), the piezoelectric element 26 (see FIG. 3) has a uniform amount of displacement without individual differences. And can discharge a uniform amount of ink droplets. Actually, the drive voltages Vh1B, Vh2B, and Vh3B are set in units of heads, and an appropriate value of the drive voltage is measured by a method as disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-90357. In the present embodiment, since the pulse PS2B and the pulse PS3B are the same, the same value is used for the drive voltage Vh2B and the drive voltage Vh3B.

  Further, the design data of the subpulses p1 to p21 can be expressed by a parameter (hereinafter referred to as TR) representing the Helmholtz resonance period in the nozzle flow path and a function using the environmental temperature as an argument. The reason why the design data is made variable according to the TR and the environmental temperature is that if these values change, the motion characteristics of the ink in the flow path change, and the discharge amount and discharge speed of the ink droplets change.

  As described above, the CPU 72 in the present embodiment generates appropriate design data in accordance with the parameters as described above. Thus, ink droplets that are stable against individual head variations and environmental changes can be obtained. Discharge is secured.

  Incidentally, an error called an input / output error exists between the design data (digital data) and the output value of the drive signal (analog signal). For example, regarding the error of the potential difference component, even if Vh2B = 30 volts (V) in the design data, if Vh2B = 30.9V in the output value of the drive signal, 3% There will be input and output errors.

  Such an input / output error is mainly caused by the D / A converters 61A and 61B, and causes the size and position of the marking dot (the region marked by the ejected ink droplet) to deviate from the target value. It is not preferable. Another significant problem is that a difference in input / output error occurs between the first and second signal generators 60A and 60B. In such a case, the size and position of the marking dots vary depending on which driving signal is used for marking. In particular, in the present embodiment, the configurations of the drive signals generated by the first and second signal generators 60A and 60B are interchanged depending on the scanning direction. The sheath position will vary, resulting in serious image quality degradation.

  Therefore, the CPU 72 as the output compensation means performs correction based on a predetermined parameter (hereinafter referred to as a correction parameter) when generating the design data so as to change the output value of the drive signal.

  Here, the correction parameter is a parameter that governs the correction amount of the design parameter. In the present embodiment, the potential difference component of the subpulse is corrected under the conditions shown in Table 1 according to the value of the correction parameter. (As a result, the drive voltage changes).

  For example, for the correction parameter value “A”, the drive voltage of the second drive signal (COM_B) is reduced by 3% so that the drive voltage of the first drive signal (COM_A) is increased by 3%. The design data is corrected. In addition, the correction parameter value “C” is not corrected, and the correction parameter value “D” is decreased by 1.5% for the driving voltage of the first drive signal (COM_A). In addition, the design data is corrected so that the drive voltage of the second drive signal (COM_B) increases by 1.5%. Information regarding the correction conditions listed in Table 1 is stored in the memory 73.

  As described above, the design data is corrected so that the drive voltage is increased for one of the first drive signal (COM_A) and the second drive signal (COM_B), and the drive voltage is decreased for the other. This is because the purpose of the correction is to compensate for the output difference between the first and second drive signals. Such correction can be performed for the time component of the sub-pulse, but is not employed in this embodiment.

  By the way, since the output difference between the first and second drive signals varies for each individual printer 1, the value of the correction parameter is optimized for each individual in order to perform compensation appropriately. There is a need. This optimization is performed according to the procedure described below.

(About the correction parameter optimization method)
Next, a method for optimizing a correction parameter will be described with reference to FIGS.
FIG. 8 is a diagram showing a drawing process of the test pattern reproduced on the paper. FIG. 9 is a timing chart showing drive signals, head control signals, and switch signals in the adjustment mode.

  The optimization of the correction parameter value is usually performed by an operator in the pre-shipment inspection process of the printer 1. Prior to the determination of the appropriate value, the printer 1 draws a test pattern as shown in FIG.

  In test pattern drawing (hereinafter referred to as an adjustment mode), ink droplets are ejected in a control mode different from the above-described normal drawing operation (hereinafter referred to as a normal mode). In the adjustment mode (FIG. 9) and the normal mode (see FIG. 5), the configuration of the drive signal and the head control signal is common, but the configuration of the switch signal is different. Thereby, in the adjustment mode, the pulse selected corresponding to each gradation data is as follows.

  That is, for the gradation data (00), the pulse PS2A of the first drive signal (COM_A ′) is supplied to the piezoelectric element 26 (see FIG. 4), and the slight vibration for suppressing the drying of the ink in the nozzles. Will occur. For the gradation data (01), the pulse PS3A of the first drive signal (COM_A ′) is supplied to the piezoelectric element 26 (see FIG. 4), and one normal dot is ejected. For the gradation data (10), the pulse PS3B of the second drive signal (COM_B ′) is supplied to the piezoelectric element 26 (see FIG. 4), and one normal dot is ejected. Further, no pulse is supplied to the gradation data (11), and the piezoelectric element 26 (FIG. 4) is not driven.

  As described above, the pulse PS3A and the pulse PS3B are the same pulse. Here, “same” means that the design data (digital data) related to both pulses PS3A and PS3B is the same in an uncorrected state, and more specifically, function information related to sub-pulses and It represents that the parameters (environment temperature, etc.) are the same. However, in this case, the output value of the pulse PS3A and the output value of the pulse PS3B are corrected in design data under a condition that is not optimized due to a hardware difference between the signal generation units 60A and 60B. (See Table 1), they do not always match.

  Thus, the normal dot (corresponding to the pulse PS3A) ejected by the gradation data (01) and the normal dot (corresponding to the pulse PS3B) ejected by the gradation data (10) are the amount (ejection amount) and speed. (Discharge speed) is not necessarily the same, and has a difference reflecting the difference in output value between the pulses PS3A and PS3B.

  In drawing the test pattern, the printer 1 first draws a first unit pattern 31a and a second unit pattern 32a that are paired with each other by forward scanning as shown in FIG. 8A (drawing step). In this case, the CPU 72 corrects the design data based on the correction parameter value “A”. That is, as shown in Table 1, the drive voltage is increased by 3% for the first drive signal (COM_A ′), and the drive voltage is decreased by 3% for the second drive signal (COM_B ′). The design data is corrected. In FIG. 8, the horizontal direction in the drawing is the scanning direction, and in the forward scanning, the head 10 (see FIG. 1) is scanned from the left to the right in the drawing.

  Here, the first and second unit patterns 31a and 32a are solid patterns marked by a specific nozzle array, and are patterns that touch each other on the drawing data (bitmap format data). ing. The first unit pattern 31a is a normal dot (corresponding to the pulse PS3A) ejected by gradation data (01), and the second unit pattern 32a is a normal dot (pulse) ejected by the gradation data (10). Each pattern is marked with (corresponding to PS3B).

  As shown in the figure, the first unit pattern 31a and the second unit pattern 32a are separated from each other. As described above, the positional relationship (alignment) between the first and second unit patterns 31a and 32a indicates such a state that the normal dot speed corresponding to the first unit pattern 31a is the first. This indicates that the speed is higher than the speed of normal dots corresponding to the unit pattern 32a of 2. If the speeds of both normal dots are the same, the unit patterns 31a and 32a should be in a positional relationship (positional relationship on the drawing data) that touches the boundary with each other. This is because the flight distance in the scanning direction from the ejection to the landing on the paper surface is shortened, so that the marking is shifted to the left (reverse scanning direction) in the figure. That is, it can be said that the alignment between the unit patterns 31a and 32a reflects the speed difference between the corresponding normal dots.

  In the present embodiment, the unit patterns 31a and 32a are drawn by the same scanning in order to favorably reflect the speed difference between corresponding normal dots in the alignment between the unit patterns 31a and 32a. If the first unit pattern 31a and the second unit pattern 32a are drawn by scanning in different directions, the marking position may be shifted due to the difference in scanning direction (difference in the flying direction of ink droplets). This is to eliminate such effects.

  By the way, the speed difference between the normal dots corresponding to the unit patterns 31a and 32a is nothing but the reflection of the output difference between the pulses PS3A and PS3B related to the respective ejections. This is because if the output values of both pulses PS3A and PS3B are exactly the same, the speeds of the corresponding normal dots should be the same. That is, it can be said that the alignment between the unit patterns 31a and 32a reflects a substantial output difference between the first and second drive signals (COM_A ′, COM_B ′).

  In this manner, by observing the alignment between the first and second unit patterns 31a and 32a, it is possible to estimate the substantial output difference of the drive signal between the first and second drive signals. Based on the estimation result, it is possible to optimize the correction parameter.

  For example, from the alignment between the unit patterns 31a and 32a, it can be estimated that the first drive signal (COM_A ') has a large output equivalent to the drive voltage with respect to the second drive signal (COM_B'). Therefore, in such a case, the correction parameter value is relatively lower (Table) so that the correction is performed such that the drive voltage decreases for the first drive signal and the drive voltage increases for the second drive signal. It can be determined that it is necessary to shift to the lower part of 1). In the present embodiment, the test pattern is continuously drawn as described below so that the optimization of the correction parameters can be performed more easily and quickly.

  After the drawing of the unit patterns 31a and 32a, the head 10 (see FIG. 1) is returned to the start position of the forward scanning, and the first and second unit patterns as shown in FIG. Drawing of 31b and 32b is performed. In drawing the unit patterns 31b and 32b constituting the pair 33b, the drawing position is entirely moved to the right (scanning forward direction), and the design data is corrected based on the correction parameter value “B” in drawing. Is performed under the same conditions as those of the unit patterns 31a and 31b.

  Similarly, the first unit pattern 31c and the second unit pattern 32c constituting the pair 33c are drawn (FIG. 8C), and the first unit pattern 31d and the second unit pattern constituting the pair 33d are drawn. Drawing of 32d (FIG. 8D), drawing of the first unit pattern 31e and the second unit pattern 32e constituting the pair 33e (FIG. 8E), the value of the correction parameter is “C”, respectively. , “D” and “E”. Further, text 36 indicating the value of the corresponding correction parameter is drawn below each pair 33a to 33e.

  By drawing the pairs 33a to 33e with different correction parameter values, the alignment between the unit patterns shows a different state for each corresponding pair. That is, compared to the separation distance between the unit patterns 31a and 32a in the pair 33a, the separation distance between the unit patterns 31b and 32b in the pair 33b is short, and the separation distance between the unit patterns 31c and 32c in the pair 33c is further shortened. Yes. In the pair 33d, the unit pattern 31d and the unit pattern 32d are in a positional relationship (positional relationship on the drawing data) such that the boundary is in contact with each other. In the pair 33e, the unit patterns 31e and 32e partially overlap at the boundary portion, and the overlap portion is a relatively high density region.

  By observing the test pattern, it is understood that the most appropriate design pattern correction related to the drawing of the pairs 33a to 33e is related to the drawing of the pair 33d (estimation step). Since the positional relationship between the unit patterns on the drawing data is most appropriately reproduced in the pair 33d, the output value of the first drive signal and the output value of the second drive signal at the time of drawing are as follows. It is because it can be estimated that it was equal.

  Thus, the operator selects an appropriate value “D” of the correction parameter from the text 36 corresponding to the pair 33d, and inputs it through the host PC 200 (see FIG. 4) (setting step). The input correction parameter appropriate value is stored in the memory 73 as storage means, and the CPU 72 corrects the design data based on the appropriate value when drawing in the normal mode thereafter. Thereby, the output difference between the first and second drive signals is substantially compensated, and a suitable image quality can be obtained.

  As described above, according to the printer 1 of the present embodiment, the digital data is corrected based on the appropriate value of the correction parameter stored in the memory 73, thereby detecting the absolute value of the output value of the drive signal and Even if a hardware mechanism for correcting the output value is not added, the output difference of the drive signal between the signal generating means 60A and 60B can be compensated with a relatively simple configuration. In addition, the drawing of the test pattern for optimizing the correction parameter is efficient because the operator can perform the general pre-shipment inspection process without using a special apparatus.

The present invention is not limited to the above-described embodiment.
For example, a specific aspect relating to the shape and arrangement of the unit pattern is not limited to the aspect of the above-described embodiment. For example, a linear pattern as shown in JP-A-7-32654 may be used as the unit pattern. The unit pattern may be drawn by micro dots or a combination of micro dots and normal dots.
In the above-described embodiment, the design data is corrected for both the first drive signal and the second drive signal (see Table 1). For example, the design of the first drive signal is designed. The data may be fixed, and only the design data of the second drive signal may be corrected.
In the above-described embodiment, the drawing apparatus includes two signal generation units (signal generation units). However, the present invention may be applied to a drawing apparatus including three or more signal generation units. it can.
In the above-described embodiment, the design data is corrected so as to uniformly increase or decrease the potential difference component of the subpulse according to the design parameter. However, more complicated correction conditions are set according to the correction parameter. Can also be set.
Moreover, each structure of each embodiment can combine these suitably, can be abbreviate | omitted, or can combine with the other structure which is not shown in figure.

The perspective view which shows the whole structure of a drawing apparatus. The perspective view which shows the external appearance structure of a head. FIG. 3 is a cross-sectional view of a main part showing an internal structure around a nozzle of a head. The block diagram which shows the electric constitution of a drawing apparatus. FIG. 5 is a timing diagram showing a drive signal, a head control signal, and a switch signal. The block diagram which shows the principal part structure of the drawing apparatus which concerns on the production | generation of a drive signal. The block diagram of a drive signal. (A)-(e) is a figure which shows the drawing process of the test pattern reproduced on a paper. FIG. 5 is a timing diagram illustrating a drive signal, a head control signal, and a switch signal in an adjustment mode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Printer as drawing apparatus, 2 ... Paper, 6 ... Carriage, 10 ... Head, 20 ... Nozzle, 26 ... Piezoelectric element as discharge drive means, 31a-31e ... 1st unit pattern, 32a-32e ... 2nd Unit patterns 33a to 33e ... pair, 36 ... text, 60A ... first signal generator as first signal generator, 60B ... second signal generator as second signal generator, 61A, 61B ... Converter, 62A, 62B ... Amplifying unit, 70 ... Print controller constituting discharge control means, 72 ... CPU as output compensation means, 73 ... Memory as storage means, 75 ... Drive signal generation circuit, 80 ... Discharge A head controller constituting the control means.

Claims (7)

A head having nozzles in a predetermined arrangement;
A discharge driving means for discharging droplets from the nozzle;
Two or more signal generating means for generating a driving signal for driving the ejection driving means based on predetermined digital data;
An ejection control means for supplying an electrical drive signal to the ejection driving means to eject droplets from the nozzles under scanning of the head;
An output compensator that substantially compensates for an output difference in the drive signal between the two or more signal generators. The output compensation means is means for correcting the digital data under a condition based on a value of a predetermined parameter,
The drawing apparatus according to claim 1, further comprising a storage unit that stores an appropriate value of the predetermined parameter. The drawing apparatus according to claim 2, wherein drawing of a test pattern for determining an appropriate value of the predetermined parameter is performed.
The test patterns are the drive signals respectively generated by the first and second signal generation means, and are generated by the drive signals generated based on the digital data that are the same when the correction is not performed. A drawing apparatus comprising first and second unit patterns drawn in a pair with each other. The drawing apparatus according to claim 3, wherein the drawing pattern draws the test pattern having a plurality of the pairs.
The drawing apparatus, wherein the output compensation unit performs the correction by drawing different values of the predetermined parameter when drawing the plurality of pairs.   The drawing apparatus according to claim 4, wherein the predetermined parameter value corresponding to the pair is drawn as text in the vicinity of the plurality of pairs.   6. The drawing apparatus according to claim 3, wherein the first unit pattern and the second unit pattern are drawn by scanning in the same direction. A head having nozzles in a predetermined arrangement; discharge driving means for discharging droplets from the nozzles; and two or more generating drive signals for driving the discharge driving means based on predetermined digital data A signal generation unit; an ejection control unit configured to supply an electrical drive signal to the ejection driving unit under the scanning of the head to eject droplets from the nozzle; and a condition based on a value of a predetermined parameter. In a drawing apparatus comprising: an output compensation unit that substantially compensates for an output difference between the plurality of signal generation units by correcting digital data; and a storage unit that stores an appropriate value of the predetermined parameter. An optimization method for optimizing the value of the predetermined parameter,
The drive signals generated by the first and second signal generation units, respectively, which are paired with each other by the drive signals generated based on the digital data that are identical to each other when the correction is not performed A drawing step of drawing the first and second unit patterns;
An estimation step of estimating an appropriate value of the predetermined parameter by observing alignment between the first and second unit patterns;
And a setting step of storing an appropriate value of the predetermined parameter in the storage unit based on an estimation result in the estimation step.

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