JP2000255047A - Printer and method for controlling printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately reproduce the color of an original image by obtaining the voltage fluctuation of a driving voltage from a reference value based on the driving state of each ink ejecting mechanism, and correcting the driving voltage so as to offset the voltage fluctuation from the reference value. SOLUTION: A head controller 72 obtains driving pulse generating data according to the temperature and the print mode preliminarily to supply the same to D/A converters 71a-71d individually. Each output is inputted to each selector circuit 74a-74f. Based on a selection control signal transmitted from a counter circuit 75a-75f corresponding to a each selector circuit 74a-74f, the output of the D/A converter 71a-71d corresponding to each nozzle frequency is selected so as to be outputted each to the corresponding counter circuit 75a-75f, and applied to a micro pump mechanism. In this case, the counter circuits 75a-75f serve as a driving state detecting means and a voltage fluctuation obtaining means, and the selector circuit 74a-74f and the D/A converters 71a-71d serve as a driving voltage correcting means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus and a printing control method, and more particularly, to a printing apparatus having a plurality of independent ink discharging mechanisms for each available color ink and a required ink discharging mechanism based on input of print data. The present invention relates to a printing apparatus that ejects color ink on a printing medium by applying a driving voltage to the printing medium to reproduce an original image and prints the printing apparatus, and a printing control method suitable for the printing apparatus.

[0002]

2. Description of the Related Art In a color printing apparatus such as an ink jet printer, three color inks of cyan (C), magenta (M) and yellow (Y) or four colors of black (K) added thereto are used. Print a color image with ink. As an ink ejection mechanism for ejecting these color inks, there are a method of ejecting color ink from a nozzle using a piezo element as an electrostrictive element, a method of ejecting ink from a nozzle using an expansion pressure of a bubble, and the like. Can be adopted. Whichever method is adopted, there is no difference in ejecting color ink by applying a predetermined drive voltage to the ink ejection mechanism. For example, in the former case, a driving voltage is applied to the piezo element to distort the crystal structure, and the distortion is used to eject the color ink in the ink chamber from the nozzle. In the latter case, a driving voltage is applied to the heater provided on the inner wall of the nozzle to generate heat, and the color ink is ejected by utilizing the expansion pressure of the bubble generated thereby.

[0003] In many cases, a plurality of nozzles are provided for a single color print head, and the print head is configured to express shades by the number of nozzles for actually discharging color ink, that is, the dot density of the color ink. Therefore, the amount of color ink ejected from each nozzle in one shot needs to be a constant reference value. This is because it is assumed that the density is expressed by the dot density, and if the ink ejection amount of one shot is different, the color of the original image will not be reproduced correctly. For this reason, the ink ejection amount for one shot is designed to be a reference value in a certain reference printing environment. However, the ink ejection amount changes depending on the ink viscosity depending on the temperature at the time of use. The drive voltage has been adjusted so as to eliminate the deviation of the ink ejection amount from the reference value caused by the temperature difference from the environment.

[0004]

The above-described conventional printing apparatus has the following problems. Certainly, the ink discharge amount changes depending on the temperature difference during use.
It also changes depending on the dot density difference of the actually applied color ink. That is, when the dot density of the actually applied color ink changes, the drive voltage itself changes according to the characteristics of the print head, and the ink ejection amount also changes. Therefore, although the deviation from the reference value of the ink ejection amount caused by the temperature difference from the reference printing environment is corrected, the deviation is corrected only when printing is performed at a certain reference dot density. In the case of printing with, the ink ejection amount deviates from the reference value, so that the original color may not be faithfully reproduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a plurality of independent ink ejection mechanisms for each available color ink, and applies a drive voltage to a required ink ejection mechanism based on input of print data. When the original image is reproduced by printing color ink on the print medium by applying the voltage, the drive voltage that fluctuates according to the situation at the time of printing is corrected, so that the color of the original image can be more faithfully reproduced. The present invention relates to a reproducible printing apparatus and a printing control method.

[0006]

In order to achieve the above object, the invention according to claim 1 includes a plurality of independent ink ejection mechanisms for each available color ink, and a required ink ejection mechanism based on input of print data. A printing apparatus that ejects color ink on a print medium by applying a drive voltage to an ink ejection mechanism to reproduce an original image and prints the image, and determines a driving state of each ink ejection mechanism in advance based on the print data. Driving state detecting means for detecting, and voltage fluctuation obtaining means for obtaining a voltage fluctuation from a reference value of a driving voltage actually applied based on the driving state of each ink ejection mechanism detected by the driving state detecting means, When a drive voltage is applied to a required ink ejection mechanism based on the print data, a voltage fluctuation from the reference value acquired by the voltage fluctuation acquisition unit is eliminated. As a configuration equipped with a drive voltage correcting means for correcting the driving voltage.

According to the first aspect of the present invention, the printing apparatus includes a plurality of independent ink ejection mechanisms for each of the available color inks. By applying a drive voltage to the mechanism, the color ink is ejected onto a print medium to reproduce and print the original image. In performing the actual printing, the driving condition detecting means detects the driving condition of each ink ejection mechanism in advance based on the print data, and the voltage fluctuation obtaining means determines the reference of the driving voltage actually applied based on the driving condition. Get the voltage fluctuation from the value. Then, at the time of actual printing, the drive voltage correction unit corrects the drive voltage so as to eliminate the voltage fluctuation and applies the drive voltage to a required ink ejection mechanism.

That is, although the drive voltage actually applied fluctuates from the reference value in accordance with the driving state of the ink discharge mechanism, the drive voltage itself is corrected so as to eliminate this, so that the actual ink discharge amount Is maintained at a constant reference value. As the ink ejection mechanism here, for example, a method using a piezo element as an electrostrictive element, a method using an expansion pressure of a bubble, or the like can be adopted. That is, in the former, the degree of distortion of the piezo element changes due to the change in the drive voltage, and in the latter, the amount of heat generated by the heater changes due to the change in the drive voltage, and the expansion pressure of the bubble changes. The discharge amount will change.

The driving condition detecting means needs to detect the driving condition of the ink ejection mechanism in each print head based on print data before actual printing. For this reason, as an example of a specific configuration of the driving situation detecting means, the invention according to claim 2 is the printing apparatus according to claim 1, wherein the driving situation detecting means stores the print data in a predetermined buffer. In addition, the driving state of each of the ink ejection mechanisms is detected based on the print data stored in the buffer. That is, the final print data is given as binary data indicating whether or not each ink ejection mechanism ejects the color ink. The binary data is stored in a buffer before printing, and the ink is read by referring to the data on the buffer. The driving state of the ejection mechanism can be detected.

The driving condition detecting means detects in advance a driving condition in which a driving voltage actually applied to the ink discharge mechanism causes a voltage fluctuation from a reference value. The driving state may be detected at the same time. That is, in a configuration in which a drive voltage is applied to each ink ejection mechanism from a certain drive power supply, if many ink ejection mechanisms are driven simultaneously, the voltage drop with respect to the drive power supply increases, and the drive voltage actually applied decreases. Become. As another example, claim 3
According to the present invention, in the printing device according to any one of claims 1 and 2, the printing device ejects color ink while printing by moving the plurality of ink ejection mechanisms in the main scanning direction. The driving status detecting means detects the driving status of each ink ejection mechanism based on print data in the main scanning direction. That is,
Focusing on one ink ejection mechanism and comparing the case of continuous drive and the case of intermittent drive, the drive voltage may be different due to the influence of residual vibration and the like, and the ink ejection amount may change. . Therefore, the driving state of each ink ejection mechanism is detected in the main scanning direction, which is the direction in which print data is arranged, and the driving voltage is corrected so as to eliminate voltage fluctuations based on the driving state.

Here, as a method for detecting the driving state in the main scanning direction, various methods can be applied and are not particularly limited. For example, the number of times that each ink ejection mechanism is driven on a main scanning line basis may be counted. Further, as another example, the invention according to claim 4 is the printing apparatus according to claim 3, wherein the drive status detecting means converts the print data in the main scanning direction for each ink ejection mechanism into a predetermined data length. While dividing,
The configuration is such that the driving status is detected in each section data unit. That is, the print data in one main scanning line is divided by a predetermined data length, and the drive status is detected in each divided data unit. For example, the number of times the ink ejection mechanism is driven may be counted in each section data, and a voltage variation during printing based on the section data may be obtained from the counted value. Further, as described above, the print data is finally represented by a sequence of binary data indicating whether or not to eject color ink. May be used to determine the driving status.

As described above, by detecting the driving state of each ink ejection mechanism in advance and eliminating the voltage fluctuation of the driving voltage actually generated in accordance with the driving state, a certain amount of ink is discharged from each ink ejection mechanism. Is discharged, but the discharge amount itself is not always the reference amount. For example, even if the ink ejection amount is constant in each ink ejection mechanism, if the ink ejection amount is larger than the reference amount as a whole, the ink ejection mechanism is expressed with a color darker than the original one. Here, various factors can be considered as factors that cause the ink ejection amount to vary as a whole, but the invention according to claim 5 has a preferable configuration for one example thereof. Wherein the voltage fluctuation obtaining means obtains a voltage fluctuation from a different reference value according to the temperature. That is, as the temperature increases, the ink viscosity decreases and the viscosity becomes less sticky, and the ink ejection amount tends to increase even when the driving voltage is constant, and conversely, the ink ejection amount tends to decrease when the temperature decreases. is there. Therefore, in obtaining the above-described voltage fluctuation, voltage fluctuations from different reference values may be obtained in anticipation of such a temperature difference, and the ink ejection amount may be a certain amount regardless of the temperature.

In addition, the reference value of the ink ejection amount varies depending on factors other than the temperature.
The printing apparatus according to any one of claims 1 to 5, wherein the voltage fluctuation obtaining unit obtains a voltage fluctuation from a different reference value according to a print mode. That is, when printing can be performed at a plurality of resolutions, when the reference value of the ink ejection amount changes depending on the printing mode, such as when the ink ejection amount is smaller at the time of high resolution printing than at the time of low resolution printing, the printing mode is changed to the actual printing mode Voltage fluctuations from different reference values are obtained accordingly.

The drive voltage correction means corrects the drive voltage actually applied so as to eliminate the voltage fluctuation acquired by the voltage fluctuation acquisition means, but various concrete structures can be applied. Is not particularly limited.
For example, a power supply means capable of dynamically changing the output voltage is provided for each ink ejection mechanism, and the output voltage of the power supply means is changed in real time so as to eliminate the actually obtained voltage fluctuation. You may. As another example, the invention according to claim 7 is the printing apparatus according to any one of claims 1 to 6, wherein the driving voltage correction unit includes a plurality of driving power supplies having different output voltages from each other. The output voltage of the drive power supply that eliminates the voltage fluctuation is selected and applied to the required ink ejection mechanism. In the invention according to claim 7 configured as described above, the drive voltage correction means includes a plurality of drive power supplies having different output voltages from each other in advance, and the drive voltage correction means for eliminating the voltage fluctuation acquired by the voltage fluctuation acquisition means. The output voltage of the power supply is selected and applied to the required ink ejection mechanism. That is, since an appropriate driving power supply may be selected from a plurality of driving power supplies, high-speed processing can be realized.

The method of detecting the driving state of each ink ejection mechanism in advance and eliminating the voltage fluctuation of the driving voltage actually generated in accordance with the driving state is not necessarily limited to a substantial device. As one example, the invention according to claim 8 includes a plurality of independent ink ejection mechanisms for each available color ink, and a drive voltage is applied to a required ink ejection mechanism based on input of print data. A printing control method for a printing apparatus that ejects color ink on a print medium to reproduce an original image and prints the image, and detects a driving state of each ink ejection mechanism in advance based on the print data. And a voltage change from a reference value of a driving voltage actually applied based on the driving state of each ink ejection mechanism detected in the driving state detecting step. And a voltage fluctuation acquiring step of applying a drive voltage to a required ink ejection mechanism based on the print data to eliminate a voltage fluctuation from the reference value acquired in the voltage fluctuation acquiring step. And a drive voltage correction step of correcting the drive voltage. In other words, there is no difference in that the present invention is not necessarily limited to a substantial device and is also effective as a method.

[0016]

As described above, according to the present invention, a plurality of independent ink ejection mechanisms are provided for each available color ink, and a drive voltage is applied to a required ink ejection mechanism based on input of print data. When the original image is reproduced by discharging the color ink on the print medium and printing is performed, the driving state of each ink discharging mechanism is detected in advance, and the voltage fluctuation of the driving voltage actually generated according to the driving state. Therefore, it is possible to provide a printing apparatus capable of faithfully reproducing the color of the original image by using the ink ejection amount as the reference value. According to the second aspect of the present invention, it is possible to provide a specific configuration for detecting in advance the driving state of each ink ejection mechanism.
Further, according to the third aspect of the present invention, since the voltage fluctuation depending on the driving state in the main scanning direction of each ink ejection mechanism is eliminated, it is possible to eliminate the color shift caused by the residual vibration. Further, according to the invention according to claim 4, since the print data in the main scanning direction is divided and the voltage fluctuation is eliminated in each divided data unit,
The original color can be reproduced more faithfully.

Further, according to the invention according to claim 5,
Since voltage fluctuations from a different reference value are obtained and eliminated according to the temperature, it is possible to eliminate a color shift due to a temperature difference during printing. Further, according to the invention of claim 6, voltage fluctuations from different reference values are acquired and eliminated according to the print mode, so that the original color can be faithfully reproduced for each print mode. Furthermore, according to the present invention, an appropriate driving power source may be selected from a plurality of driving power sources and applied to the corresponding ink ejection mechanism, so that high-speed processing can be realized. Further, according to the invention of claim 8, it is possible to provide a print control method capable of faithfully reproducing the color of the original image by correcting the drive voltage in the same manner.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram illustrating an example of a printing system to which a printing apparatus according to an embodiment of the present invention is applied. This printing system includes a personal computer 10 and a printer 50 as a printing device.
The personal computer 10 generates predetermined print data based on color image data captured from a digital still camera, a scanner, or the like, and outputs the generated print data to the printer 50. The printer 50 applies color ink on a print medium based on the print data. Print while reproducing the original color image. Here, the color image data represents the strength of each element color while separating the color image for each predetermined element color.

FIG. 2 shows a schematic configuration of a typical personal computer 10. The personal computer 10 is a CP that is the center of arithmetic processing.
U11, and a CPU bus 1
2 and the secondary cache 13 and the data bus unit 1
4 and the system controller 15 are connected. In recent personal computers, the clock speed of the CPU bus 12 has been increased in order to improve the processing efficiency.
Are the data bus unit 14 and the system controller 15
Via the CPU 11. The memory 16 includes a ROM area such as a BIOS area and a RAM area.

Similarly, interfaces cannot be directly connected to the fast CPU bus 12, and the data bus unit 14 and the system controller 15 provide a PCI bus 17 which is a general-purpose high-speed bus. This PCI
A common interface 18 for connecting a floppy (registered trademark) disk is connected to the bus 17 together with a communication interface such as a PS / 2 port, a parallel port, or a serial port that the personal computer 10 itself has directly. Required hard disk and C
A bus master 19 for connecting a D-ROM and performing DMA transfer is also connected. A PCI device 21 can be directly connected to the PCI bus, and an ISA bus 2 which is an old general-purpose bus having a narrow data width is connected via an ISA bridge 22.
3 via the ISA bus 23.
The device 24 can be connected.

FIG. 3 shows peripheral devices for the personal computer 10. A keyboard 25 and a mouse 26 are connected to PS / 2.
The printer 50 is connected to the common interface 18 via a parallel port, and the modem 27 is connected to the common interface 18 via a serial port. Scanner 28
Is connected to a PCI bus 17 via a SCSI card 21a as a PCI device 21. Various external devices can be connected to the SCSI card 21a, and a magneto-optical storage device 31 and the like can be connected. it can.
The display 29 is connected via the display controller card 21b, and is connected to the hard disk 19a.
And the CD-ROM drive 19 b are connected to the PCI bus 17 via the bus master 19.

Various devices are provided as the ISA device 24. If the PCMCIA card 24a is used, the PCMCIA card socket 32 can be connected.
A memory card 33 on which image data is recorded is mounted to facilitate data input / output. The memory card 33 is a digital still camera 34, and it is easy to input data from another mobile personal computer or the like. In addition to the above, an external display can be connected to the personal computer 10 via a video card, or a LAN card can be connected to a network, or connected to another external device via an infrared communication device. It is also possible to do.

The above is the schematic configuration of the hardware of the personal computer system. On the premise of such hardware, software is executed on the personal computer 10 in the manner shown in FIG. That is, the BIOS 42 is executed on the basis of the hardware 41, and the operating system 43 and the application 44 are executed on the BIOS. Basically, the operating system 43 accesses the hardware 41 via the BIOS 42 or directly,
The application 44 exchanges data with the hardware 41 via the operating system 43. For example, to read data from the hard disk 19a, access the hardware 41 via the operating system 43. In addition, various drivers for controlling the hardware 41 can be incorporated in the operating system 43, and the incorporated drivers execute various controls as a part of the operating system 43. Examples of the driver include a display driver for controlling display on an external display via a video card, and a printer 5.
For example, a printer driver for executing print control to 0 is incorporated.

FIG. 5 is a schematic flowchart showing a processing procedure by the printer driver. In the figure, in step S110, rasterized print data is input and a predetermined color conversion process is executed. That is, the personal computer 10 handles RGB gradation data, while the printer 50 uses cyan (C), magenta (M), yellow (Y), black (K), or light cyan light cyan (c). ),
The tone data of each component to which light magenta (m) is added is handled. Since the color space is different, RGB is converted to CMYK or CcMmYK tone data. Then, in the next step S120, the image is binarized from 256 gradations to two gradations, and in step S130, a control file such as initialization, page break, line feed, etc. is added, and a spool file is generated and transferred to the printer 50.
Then, after the spool file is transferred to the printer 50, the process shifts to the printer 50 and printing is performed as described later.

On the other hand, FIG. 6 shows a schematic configuration of the printer 50, and FIGS. 7 and 8 show the configuration of the print head and the principle of ink ejection. The printer 50 according to the present embodiment is a color inkjet printer, which performs printing using six color inks of CcMmYK.
Four color inks of CMYK may be used. The printer 50 is provided with a parallel I / O 51 for connecting to a parallel port of the personal computer 10.
Transmission and reception of commands and print data are performed by parallel communication. The parallel communication is an interface capable of executing a bidirectional communication such as a one-way communication Centronics method, nibble, ECB, and EPP. Parallel I / O
Reference numeral 51 is connected to a gate array 52, and is connected to a bus 53 via the gate array 52. A system ROM 55, a character generator ROM 56, and a D-RAM 57 are connected to the bus 53 together with the CPU 54.
The PU 54 executes the printer control program written in the system ROM 55 while using the D-RAM 57 as a work area or the like, and performs printing using the font data or the like written in the character generator ROM 56.

The specific printing mechanism is the gate array 5
2, the carriage motor 58 reciprocates (main-scans) the print head 61 with respect to the printing paper while discharging the required color ink, and the paper feed motor 62 By feeding the printing paper (sub-scanning), printing can be performed on almost the entire surface of the printing paper. The gate array 52 to which the print head 61 is connected includes a timer counter 63 for generating a clock used by the system and a non-volatile EEPROM for storing settings.
An M64 and an operation panel 65 are provided.

The print head 61 is composed of six print head units 61a corresponding to the respective color inks of CcMmYK. Each print head unit 61a has a fine conduit 61a3 from the color ink tank 61a1 to the nozzle 61a2. An ink chamber 61a4 is formed at the end of the conduit 61a3. The wall surface of the ink chamber 61a4 is formed of a flexible material, and a piezo element 61a5, which is an electrostrictive element, is provided on the wall surface. The piezo element 61a5 has a crystal structure that is distorted by applying a voltage, and performs high-speed electrical-mechanical energy conversion. As shown in FIG. Press to reduce the volume of the ink chamber 61a4. Then, a predetermined amount of color ink particles is vigorously ejected from the nozzle 61a2 communicating with the ink chamber 61a4, and is applied to the print medium in the form of dots. This pump structure is called a micro pump mechanism.

A single print head unit 61a is formed with a total of 64 nozzles 61a2 in two rows, and one print head unit 61a is provided with 64 micropump mechanisms to correspond to this. Therefore, each nozzle 61a2 can independently eject color ink. Here, if the ink is ejected from a large number of nozzles 61a2 at the same time, the dot density of the color ink applied on the print medium is increased and a darker color is expressed, and the color ink is simultaneously ejected from a smaller number of nozzles 61a2. When the ink is ejected, the dot density of the color ink applied on the print medium is reduced, and a lighter color is expressed, whereby the shade of each color can be expressed. In the present embodiment, the above-described micropump mechanism is employed, but, needless to say, the mechanism for discharging the color ink is not limited to this. For example, a configuration may be adopted in which a heater provided on the inner wall of the nozzle is operated to generate heat, and the color ink is ejected by utilizing the expansion pressure of the bubble generated by the heater.

In order to actually eject the color ink from the individual nozzles 61a2, a drive pulse as shown in FIG. 9 is generated, and the applied voltage having the amplitude is applied to the corresponding piezo element 61a5 of the micropump mechanism. Then, one shot of color ink is ejected from the nozzle 61a2 per one of the driving pulses. As a specific circuit configuration,
A predetermined pulse power supply is provided inside the printer 50, and a predetermined switching circuit is interposed between the pulse power supply and each of the micropump mechanisms. It can be configured to apply a drive pulse.

Of course, here, each nozzle 61a2
It is desired that the amount of ink ejected for one shot in is a predetermined fixed amount. Because, as described above, it is assumed that the shade of color is expressed by the difference in dot density of the color ink applied on the print medium, and if the ink ejection amount of one shot changes, the color ink Even if the dot density is the same, there is a possibility that a difference occurs in the dot area of the color ink applied on the print medium, resulting in color shading. Here, as a factor that causes a difference in the ink ejection amount for one shot, a temperature difference during printing can be considered. In other words, when the temperature at the time of printing increases, the viscosity of the color ink decreases and the color ink becomes less sticky, so that the ink ejection amount of one shot tends to increase, and conversely, the ink ejection amount of one shot decreases when the temperature decreases Tend to.

Another factor may be a dot density difference in the main scanning direction of the color ink actually applied. In other words, a high dot density in the main scanning direction means that one micropump mechanism is driven continuously, and the amplitude of the driving pulse actually applied fluctuates due to the influence of residual vibration. I will. Since the amplitude of this drive pulse corresponds to the voltage applied to the piezo element 61a5, the degree of distortion is deviated and each nozzle 61a2
In this case, the ink ejection amount of one shot fluctuates as a whole, causing a color difference. Here, the dot density in the main scanning direction can be regarded as a frequency at which the color ink is ejected from the nozzles 61a2, that is, a frequency. Therefore, the dot density in the main scanning direction is hereinafter referred to as a nozzle frequency. To When the dot density of the color ink applied at one time as the print head unit 61a increases, the influence of the voltage drop on the pulse power supply is also considered. And it is sufficient to incorporate a constant voltage circuit that eliminates the fluctuation of the power supply voltage, so that the influence of such a voltage drop is not considered.

By the way, conventionally, the ink ejection amount of one shot is corrected by controlling the amplitude of the driving pulse depending on the temperature. The correction result in this case is as shown in FIGS. 10 and 11. Become. FIG. 10 shows that, during normal dot printing with a resolution of 720 dpi, the ink ejection amount for one shot is plotted on the vertical axis and the nozzle frequency is plotted on the horizontal axis, and the corrected ink ejection amount changes depending on the temperature and the nozzle frequency. It is shown that. In the figure, the ink ejection amount of one shot changes depending on the frequency characteristics, temperature, and nozzle frequency of the print head unit 61a. However, in this normal dot printing, even if the temperature changes, the nozzle frequency is maximized (solid). In this case, the amplitude of the drive pulse is controlled so that the ink ejection amount becomes a constant reference value at the time of printing. The reason why the reference is made when the nozzle frequency becomes the maximum is that emphasis is placed on avoiding missing dots or excessive ink during solid printing. Therefore, even if the temperature is constant, if the nozzle frequency changes to the low frequency side, the ink ejection amount for one shot tends to deviate from the reference value. Specifically, when the temperature is high (40 ° C.), the ink ejection amount of one shot tends to decrease with a decrease in the nozzle frequency, and when the temperature is low (15 ° C.), the nozzle frequency decreases. Accompanying this, the amount of ink discharged per shot tends to increase.

On the other hand, FIG. 11 shows that the resolution is 1440 dpi.
Similarly, the corrected ink ejection amount during microdot printing is shown. At the time of microdot printing, the ink discharge amount also changes depending on the temperature and the nozzle frequency. However, since the reference one-shot ink discharge amount is smaller than that at the time of normal dot printing, the temperature and the nozzle frequency change. It can be said that the influence of the difference is small and that a problem such as excessive ink hardly occurs. For this reason, the amplitude of the drive pulse is controlled such that the ink ejection amount becomes a constant reference value even when the temperature changes, based on the nozzle frequency on the low frequency side, which is assumed to be actually used frequently. I have.
Therefore, even if the temperature is constant, if the nozzle frequency changes to the high frequency side, the ink ejection amount for one shot also tends to deviate from the reference value. Specifically, although the degree of the deviation varies depending on the temperature, it increases as the nozzle frequency increases.
The ink ejection amount of the shot tends to increase.

Therefore, in order to eliminate the above-described deviation, in addition to controlling the amplitude of the driving pulse according to the temperature, the amplitude of the driving pulse according to the nozzle frequency may be controlled. Therefore, in the present embodiment, the printer 50
A circuit configuration as shown in FIG. 12 is constructed by the gate array 52, and the amplitude of the driving pulse is controlled based on the temperature and the nozzle frequency by this circuit configuration. In the figure, D / A converters (DAC) 71a, 71
b, 71c, and 71d are for generating drive pulses, and control data (DCTRL) such as a synchronization clock and data for driving pulse generation (DADA) are respectively supplied from the head controller 72 which is the center of the circuit configuration.
TA). Each D / A converter 71a, 7
1b, 71c, and 71d generate drive pulses, which are analog signal voltages, by converting drive pulse generation data (DATAT) from the head controller 72 into analog signals. Note that each of the D / A converters 71a, 71
b, 71c, 71d are provided with a predetermined reference power supply, and are configured to keep the output constant by comparing the reference power supply voltage with the output voltage. Therefore, each of the D / A converters 71a, 71b, 71c, No voltage drop occurs in the output voltage at 71d.

Here, the D / A converter 71a,
Each of 71b, 71c, and 71d generates a drive pulse corresponding to a different nozzle frequency depending on the temperature during printing. As shown in FIG. 13, the D / A converter 71a is on the high frequency side, and the D / A converter is on. The 71d side corresponds to the low frequency side. That is, as described above, even if the temperature is constant, the amount of ink discharged for one shot varies according to the nozzle frequency, so that the D / A converter 71a,
A drive pulse is generated such that the ink ejection amount of one shot at a temperature at the time of actual printing becomes a reference value corresponding to four nozzle frequencies defined in advance in 71b, 71c, and 71d. For example, if the temperature is 40 ° C. during normal dot printing, as shown in FIG. 10, the ink ejection amount of one shot decreases on the low frequency side, so that the head controller 72 adjusts the low frequency to compensate for the decrease. To the D / A converter 71d on the side, drive pulse generation data for increasing the amplitude of the drive pulse is transmitted more than the D / A converter 71a on the high frequency side.

FIG. 14 shows a processing procedure at the time of the amplitude control by the head controller 72. In FIG. 7, the head controller 72 acquires the current temperature from a predetermined thermistor 73 in step S210. In the next step S220, drive pulse generation data is acquired such that the ink ejection amount of one shot becomes a reference value corresponding to the above four types of nozzle frequencies at the acquired temperature at the present time. A converter 71a, 7
1b, 71c and 71d. Of course, as can be seen from FIGS. 10 and 11, the deviation of the ink ejection amount according to the nozzle frequency differs depending on the print mode of normal dot printing or microdot printing. For this reason, the print mode is acquired at the time of communication with the printer driver, and drive pulse generation data corresponding to the print mode and the actual temperature is transmitted. More specifically, data to be transmitted according to the temperature and the print mode may be obtained in advance by experiment and stored as a table, and the relevant data may be acquired and transmitted as appropriate.

Then, while the print head 61 is conveyed in the main scanning direction by the carriage motor 58 as described later, the corresponding nozzle 61a2 of each print head unit 61a
And the actual printing is started. The head controller 72 waits in step S230 until printing of one line is completed, and then executes the same processing in order until it determines in step S240 that printing of the last line is completed. Therefore, as shown in the timing chart of FIG. 15, the temperature is detected immediately before the printing of each line is started, and if there is a temperature difference, the D / A is adjusted so as to eliminate the ink ejection amount due to the temperature difference. Converter 71
Since the data for generating the drive pulse is sent to a, 71b, 71c, and 71d, their outputs are corrected substantially in real time.

D / A converters 71a, 71b, 71
The drive pulse output from each of c and 71d is C
The signals are input to selector circuits 74a to 74f provided corresponding to the respective color inks of cMmYk. Here, since each of the selector circuits 74a to 74f has the same configuration as each other, the description will be given focusing on the selector circuit 74a corresponding to the C color ink for convenience of explanation. FIG.
Is a schematic diagram conceptually showing the configuration of the selector circuit 74a. In the figure, D / A converters 71a, 71
Each drive pulse from b, 71c, and 71d is branched into 64 inside the selector circuit 74a, and is input to 64 selector switches SL1 to SL64 disposed inside, respectively. That is, each of the selector switches SL1 to SL
64, D / A converters 71a, 71b,
Four drive pulses from 71c and 71d are input. Here, each selector switch SL1 to S
L64 selects and outputs any one of the four input driving pulses, and the selector circuit 74a outputs 64 independent driving pulses. The D / A converters 71a and 71 are controlled by the selector switches SL1 to SL64.
Which of the outputs b, 71c and 71d is selected is determined by a selection control signal (SLTINFO signal) described later.

A counter circuit 75a is provided downstream of the selector circuit 74a, and receives 64 drive pulses from the selector circuit 74a. Here, the counter circuit 75a includes 64 counter units CT1 to CT
64, and each of the selector switches SL1 to SL1
The driving pulse from SL64 is input. Each of the counter units CT1 to CT64 causes 6
Driving pulses are appropriately applied to the four micropump mechanisms, and color ink is ejected from the corresponding nozzles 61a2 by the micropump mechanisms to which the driving pulses are actually applied.

On the other hand, the control circuit (HE) such as a synchronization clock is supplied from the head controller 72 to the counter circuit 75a.
ADCTRL) and the actual print data (HEADDAT)
A) are supplied. The print data here is Cc
The print data is given as binary data indicating whether or not to add dots in the print head unit 61a for each color ink of MmYK. More specifically, as described above, each print head unit 61a is provided with 64 nozzles 61a2, and discharges ink from required nozzles 61a2 while moving the print head 61 in the main scanning direction. Accordingly, the print data is given as bit data indicating whether or not ink is ejected from each nozzle 61a2 with respect to the displacement in the main scanning direction as shown in FIG. It should be noted that, in the example shown in the figure, a bit for ejecting ink is shown as an ON bit, and a bit for not ejecting ink is shown as an OFF bit.

In the counter circuit 75a, such print data is distributed and input to the counter units CT1 to CT64 corresponding to the respective nozzles 61a2. here,
Each of the counter units CT1 to CT64 detects the number of ON bits, that is, the nozzle frequency, by referring to the bit data in units of 8 bits from the first bit while holding the input bit data for each nozzle 61a2 in a predetermined print buffer. I do. As a result, if the ON bits are 7, 8/8 bits, the output of the D / A converter 71a is the ON bits 5, 6/8 bits, the output of the D / A converter 71b is the ON bits 3, 4/8 bits, If the output bits of the D / A converter 71c are on bits 1 and 2/8, the output of the D / A converter 71d is determined as follows.
It is determined which of the D / A converters 71a, 71b, 71c and 71d is to be selected by the selector switches SL1 to SL64 on the previous stage of the 64.

Then, a control circuit (not shown) in the counter circuit 75a generates the above-described selection control signal based on the selection contents determined by each of the counter units CT1 to CT64 and sends it to the selector circuit 74a. Then, in the selector circuit 74a, a control circuit (not shown) receives the selection control signal and causes each of the selector switches SL1 to SL64 to select the output of the corresponding D / A converter based on the selection control signal. Counter unit CT1
To CT64 are selector switches SL1 to SL, respectively.
A control mechanism for outputting / interrupting the drive pulse from the drive buffer 64 is provided. At the time of actual printing, bit data stored in each print buffer is sequentially referred to at a predetermined timing. , And operates so as not to output the drive pulse if the bit is an off bit. Then, a drive pulse is appropriately applied to the corresponding micro pump mechanism, and the color ink is ejected from the nozzle 61a2 according to each drive pulse. At this time,
The amplitude of the drive pulse applied to each micropump mechanism is adjusted so as to cancel the deviation of the ink ejection amount depending on the temperature and the nozzle frequency.
A reference amount of color ink is ejected from a2, and the original color is faithfully reproduced.

Each of the counter units CT1 to CT64 has 8
After completing the processing for the bit data for the bits,
The number of on bits in the next 8 bits of bit data is obtained. Then, the outputs of the selector switches SL1 to SL64 are selected in accordance with the respective acquired on-bit numbers, and a selection control signal based on the selected content is generated and transmitted to the selector circuit 74a so as to switch from the previous signal. Then, similarly, an appropriate drive pulse is appropriately applied to the micropump mechanism according to the nozzle frequency for the next 8 bits of data.
, A reference amount of color ink is ejected. Thereafter, until all the data on the print buffer has been processed, 8
The same processing is executed in bit units. The selector circuit 74a and the counter circuit 7 for the C color ink
Although 5a has been described, the selector circuits 74b to 74f and the counter circuits 75b to 75f are provided for the other cMmYk color inks, and it goes without saying that the same operation is performed.

In this embodiment, the counter circuit 75
a, 64 counter units CT1 to CT64 are provided, and each is configured to detect the nozzle frequency by referring to the bit data for each nozzle 61a2. Of course, if the processing speed of the counter unit is high, A configuration in which one counter unit refers to the bit data of each of the plurality of nozzles 61a2 while switching them and detects each nozzle frequency is also possible. In the present embodiment, the nozzle frequency is detected in units of 8 bits. However, the nozzle frequency may be detected by other methods. For example, FIG.
As shown in (1), paying attention to the bit data on the print buffer in one counter unit, the output of the D / A converters 71a, 71b, 71c, 71d according to the on / off status of the preceding three bits for each on bit. May be sequentially switched. In the example shown in the figure, the D / A converters 71a and 71b respectively depend on whether the preceding bit of each ON bit is an ON bit, the preceding bit is an OFF bit, the preceding two bits are OFF bits, and the preceding three bits are OFF bits. , 71c, 71d are selected. As for the first bit, the output of the D / A converter 71d is selected on the assumption that the preceding three bits are off bits. That is, even in such a configuration, the nozzle frequency is still detected, and may be changed as appropriate.

As described above, in the present embodiment, in performing actual printing, the nozzle frequency of each nozzle 61a2 is detected by the counter circuits 75a to 75f, and the reference value of the driving pulse generated according to the nozzle frequency is determined. A drive pulse that eliminates the amplitude fluctuation of the counter is determined, and the counter circuits 75a to 75f constitute driving state detecting means in the former sense, and constitute voltage fluctuation acquiring means in the latter sense. Also, the counter circuit 75a
To 75f, in cooperation with the selector circuits 74a to 74f, respectively, so that the D / A converters 71a, 71b, 71c, 71 can eliminate amplitude fluctuations from the reference value of each drive pulse.
By selecting and outputting a drive pulse from d and applying a drive pulse to a required micropump mechanism according to actual print data, color ink is ejected from each nozzle 61a2. Such a circuit configuration constitutes the drive voltage correction means.

Next, the operation of this embodiment having the above configuration will be described. When a print request is issued from the application on the personal computer 10, the printer driver starts up, inputs the rasterized print data, converts the RGB gradation data to the CcMmYK gradation data (step S110), and prints the 256 gradations. Are binarized into two gradations (step S120), a predetermined control code is added, and a spool file is generated and output (step S130). The print data is transferred to the printer 50 via a predetermined parallel interface, and the printer 50 stores the print data in the D-RAM 57 via the parallel I / O 51, the gate array 52, and the bus 53 in order. The CPU 54 executes the printer control program written in the system ROM 55 while using the D-RAM 57 as a work area, and executes the character generation RO.
The printing process is executed using the font data and the like written in M56.

In this printing step, bit data indicating whether or not to apply ink to each print head unit 61a of each color is stored in the head controller 72 of the gate array 52.
Through the head controller 72, and counter circuits 75a to 75c for each print head unit 61a.
5f is provided with the bit data. Here, in each of the counter circuits 75a to 75f, 64 nozzles 6
In each of the counter units CT1 to CT64 corresponding to 1a2, the bit data is stored in the print buffer, and the nozzle frequency is detected by counting the number of ON bits with reference to the first 8 bits of the bit data. Then, in each of the counter circuits 75a to 75f, a predetermined control circuit generates a selection control signal based on the nozzle frequency detected by the counter units CT1 to CT64, and transmits the selection control signal to the corresponding selector circuits 74a to 74f.

On the other hand, the head controller 72 acquires the temperature from the thermistor 73 immediately before the actual printing is started (step S210), and based on the acquired temperature and the print mode acquired at the time of communication with the printer driver. The driving pulse generation data is supplied to each of the D / A converters 71a, 71b, 71c, 71d (step S220). The D / A converters 71a, 71b, 7
1c and 71d generate drive pulses corresponding to four predefined nozzle frequencies under the actual printing temperature by converting the drive pulse generation data into analog data. By applying a voltage to the micropump mechanism corresponding to the nozzle frequency, a reference amount of ink can be ejected from each nozzle 61a2. More specifically, the head controller 72 acquires drive pulse generation data obtained in advance by experiment according to the temperature and the print mode, and supplies the data to the D / A converters 71a, 71b, 71c, and 71d individually. .

D / A converters 71a, 71b, 71
The outputs of c and 71d are connected to the selector circuits 74a to 74f, respectively.
Is input to Here, each of the selector circuits 74a to 74f
Are D / A converters 71a, 71b, and 7 corresponding to the nozzle frequency of each nozzle 61a2 based on the selection control signals transmitted from the corresponding counter circuits 75a to 75f.
The outputs of 1c and 71d are selected and output to the corresponding counter circuits 75a to 75f. Each counter circuit 75
a to 75f refer to each bit in order from the head bit of the bit data for each nozzle 61a2 at a predetermined timing.
The drive pulse from 4f is applied to the corresponding micropump mechanism. Then, the micropump mechanism to which the driving pulse is applied discharges one shot of color ink. At this time, the reference amount of color ink is discharged from each nozzle 61a2 as described above. And
When the printing of eight bits is completed, each of the counter circuits 75a to 75f similarly performs the D / A converter 71a, 71b, 71c, 71 based on the bit data of the next eight bits.
The output of d is selected, switched to a selection control signal based on the selected content, and transmitted to the selector circuits 74a to 74f.

Then, in the selector circuits 74a to 74f which have received the selection control signal, the D / A converters 71a, 71b,
The outputs of 71c and 71d are selected and output to the corresponding counter circuits 75a to 75f. Thereafter, similarly, every time printing is completed in units of 8 bits, the counter circuit 75
Appropriate driving pulses are supplied to a to 75f. When the printing for one line is completed, the head controller 72 acquires the temperature from the thermistor 73 again (steps S230, S240, S210), and according to the acquired temperature, the D / A converters 71a, 71b, 71c, 7
The drive pulse generation data supplied to 1d is updated (step S220). Thereafter, in the same manner as described above, the printing process is performed while selecting the driving pulse in units of bit data of 8 bits, and the printing is completed when the process for all the lines is completed (step S240).

As described above, the printer 50 has the CcMmYK
Is provided with 64 nozzles 61a2 capable of independently ejecting color ink for the print head unit 61a of each color, and a counter circuit 75a for executing actual printing.
75f detect the nozzle frequency in the print head unit 61a of each color in advance, and based on the temperature at the time of printing and the nozzle frequency, the D / A converters 71a to 71d.
And selector circuits 74a to 74f cooperate with each nozzle 6
Since a drive pulse for discharging a reference amount of color ink is generated from 1a2 and the color ink is discharged using this drive pulse, the color of the original image can be reproduced more faithfully.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram illustrating an example of a printing system to which a printing apparatus according to an embodiment of the present invention has been applied.

FIG. 2 is a schematic block diagram of a personal computer.

FIG. 3 is a schematic block diagram showing a connection status of a peripheral device to a personal computer.

FIG. 4 is a diagram showing a configuration of software of a personal computer.

FIG. 5 is a flowchart illustrating a processing procedure of a printer driver.

FIG. 6 is a schematic block diagram of a printer.

FIG. 7 is a schematic explanatory view of a print head in the printer.

FIG. 8 is a schematic explanatory view showing a situation where color ink is ejected by the print head.

FIG. 9 is a waveform diagram showing a drive pulse applied to a micro pump mechanism of the print head.

FIG. 10 is a diagram showing that the ink ejection amount changes due to a change in nozzle frequency in a drive pulse correction process according to a conventional example (during normal dot printing).

FIG. 11 is a diagram showing that the ink ejection amount changes due to a change in the nozzle frequency in the drive pulse correction process according to the conventional example (at the time of microdot printing).

FIG. 12 is a block diagram illustrating a circuit configuration for performing amplitude control of a drive pulse based on a temperature and a nozzle frequency.

FIG. 13 is an explanatory diagram showing that the D / A converter associated with the nozzle frequency differs depending on the level of the nozzle frequency.

FIG. 14 is a flowchart illustrating a procedure for controlling the amplitude of a driving pulse by a head controller.

FIG. 15 is a timing chart showing that the drive pulse amplitude is updated in accordance with the temperature every time one line is printed.

FIG. 16 is a schematic diagram showing a configuration of a selector circuit and a counter circuit.

FIG. 17 is a diagram showing that print data is constituted by bit data for each nozzle.

FIG. 18 is a diagram illustrating a method for detecting a nozzle frequency according to a modification.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Personal computer 11 ... CPU 12 ... CPU bus 13 ... Secondary cache 14 ... Data bus unit 15 ... System controller 16 ... Memory 17 ... PCI bus 18 ... Common interface 19 ... Bus master 19a ... Hard disk 19b ... CD-ROM drive 21 ... PCI Device 21a SCSI card 22 ISA bridge 23 ISA bus 24 ISA device 24a PCMCIA card 25 Keyboard 26 Mouse 27 Modem 28 Scanner 29 Display 31 magneto-optical storage device 32 PCMCIA card socket 33 Memory Card 34 Digital still camera 41 Hardware 42 BIOS 43 Operating system 43 a Printer driver 44 Application 50 Printer 51 ... Parallel I / O 52 ... Gate Array 53 ... Bus 54 ... CPU 55 ... System ROM 56 ... Character Generator ROM 57 ... D-RAM 58 ... Carriage Motor 61 ... Print Head 61a ... Print Head Unit 61a1 ... Color Ink Tank 61a2 ... Nozzle 61a3 Pipe line 61a4 Ink chamber 61a5 Piezo element 62 Paper feed motor 63 Timer counter 64 EEPROM 65 Operation panel 71a-71d D / A converter (DAC) 72 Head controller 73 Thermistor 74a-74f ... Selector circuits 75a to 75f ... Counter circuits SL1 to SL64 ... Selector switches CT1 to CT64 ... Counter unit

Claims (8)

[Claims] A plurality of independent ink ejection mechanisms for each available color ink; and a drive voltage applied to a required ink ejection mechanism based on input of print data, thereby ejecting the color ink onto a print medium. A printing apparatus that reproduces an original image and prints the original image, based on the print data, a driving state detecting unit that detects a driving state of each ink ejection mechanism in advance, and each ink detected by the driving state detecting unit. Voltage fluctuation acquiring means for acquiring a voltage fluctuation from a reference value of a driving voltage actually applied based on a driving state of the ejection mechanism; and applying a driving voltage to a required ink ejection mechanism based on the print data. A driving voltage correction unit that corrects the driving voltage so as to eliminate the voltage fluctuation from the reference value obtained by the voltage fluctuation obtaining unit. Characteristic printing device. 2. The printing apparatus according to claim 1, wherein the drive status detection means stores the print data in a predetermined buffer, and discharges each of the inks based on the print data stored in the buffer. A printing apparatus for detecting a driving state of a mechanism. 3. The printing apparatus according to claim 1, wherein the printing apparatus ejects color ink while moving the plurality of ink ejection mechanisms in a main scanning direction to perform printing. In addition, the driving status detecting means includes:
A printing apparatus for detecting a driving state of each ink ejection mechanism based on print data in a main scanning direction. 4. The printing apparatus according to claim 3, wherein the drive status detecting means divides the print data in the main scanning direction for each ink ejection mechanism by a predetermined data length, and divides the print data in units of each divided data. A printing apparatus characterized in that the driving state is detected. 5. The printing apparatus according to claim 1, wherein the voltage fluctuation acquiring unit acquires a voltage fluctuation from a reference value different according to a temperature. apparatus. 6. The printing apparatus according to claim 1, wherein the voltage fluctuation acquiring unit acquires a voltage fluctuation from a different reference value according to a print mode. Printing device. 7. The printing apparatus according to claim 1, wherein the drive voltage correction means includes a plurality of drive power supplies having different output voltages from each other, and the drive voltage correction means eliminates the voltage fluctuation. A printing apparatus wherein an output voltage of a power supply is selected and applied to the required ink ejection mechanism. 8. A color ink is ejected on a print medium by providing a plurality of independent ink ejection mechanisms for each available color ink and applying a drive voltage to a required ink ejection mechanism based on input of print data. A print control method for a printing apparatus that reproduces an original image and prints the original image, comprising: a drive status detection step of detecting a drive status of each ink ejection mechanism in advance based on the print data; A voltage fluctuation obtaining step of obtaining a voltage fluctuation from a reference value of a driving voltage actually applied based on a driving state of each ink discharging mechanism detected in the above, and a required ink discharging mechanism based on the print data. A drive voltage correction step for correcting the drive voltage so as to eliminate the voltage change from the reference value obtained in the voltage change obtaining step when the drive voltage is applied. And a print control method.