JP4277459B2 - Ink jet printer and ink particle ejection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for generating a voltage waveform used for driving a head in an ink jet printer, and more particularly to a technique around a circuit for generating an analog waveform from digital data.
[0002]
[Prior art]
In general, a printer used in connection with a host computer receives a print command from the host computer, interprets the command, and temporarily develops image data included therein in an image buffer memory. In an ink jet printer, the data developed in the image buffer memory is generally based on the number of dots drawn during one main scanning of the head, that is, data for one band as a basic unit.
[0003]
In recent ink jet heads, for example, 96 nozzles per color are arranged in a row in the sub-scanning direction in order to improve printing quality and printing speed. Then, the image processing unit of the printer develops data in each bit of the image buffer with a one-to-one correspondence with each of the nozzles. When the bit is standing, the ejection of the ink particles is turned on, and when the bit is not standing, the ejection is turned off.
[0004]
In a scene where ink particles are ejected, the size of the ink particles ejected can be determined in order to obtain a higher quality printed matter. Below, the outline | summary of the typical technique for implement | achieving it is demonstrated.
[0005]
FIG. 1 shows the hardware configuration of an inkjet printer. In FIG. 1, the controller 2 is a control board mounted in the printer, and causes the print engine 3 to execute a printing operation according to data input from the interface device 4. A CPU (Central Processing Unit) 23 controls each unit in the controller 2 by executing a program stored in a ROM (Read Only Memory) 21. On the main bus of the controller 2, a RAM (Random Access Memory) 22 serving as a main storage device of the CPU 23 and a PROM (Programmable Read Only Memory) for recording various setting items are stored. Storage element) 24 is connected.
[0006]
The custom IC chip 26 in the controller 2 actually sends various signals to the print engine 3 in accordance with a print command interpreted by the CPU 23 and operates it. That is, the custom IC chip 26 plays a role as an engine control unit that controls the portion related to the printing drive of the printer.
[0007]
The motor drive signal sent from the custom IC chip 26 via the signal line 28 causes the motor 29 to feed the printing paper or move the head unit 31 mounted on the carriage 30.
[0008]
The signal line 32 is a bus line having a bit width corresponding to the number of nozzles mounted on the print head. Based on the image buffer data developed in the RAM 22, a signal for discharging or stopping ink discharge for each nozzle. Are sent to the print head. At this time, the drive voltage of the print head follows the analog voltage waveform generated by the D / A converter IC chip 33.
[0009]
The analog signal for determining the size of the ink particles is once sent to the digital / analog converter 33 in the form of a collection of digital vector data. Here, the digital signal is converted into an analog trapezoidal wave as shown in FIG. 2 as an example, and then sent to the ink nozzle driving switching semiconductor element 35. A transistor 34 having an appearance as shown in FIG. 3 is used to generate the analog voltage.
[0010]
FIG. 4 shows the configuration of the head drive circuit in the case of a system in which ink is ejected from the nozzles by utilizing the expansion action of the piezoelectric vibrator as an example of a typical ink jet printer.
[0011]
In FIG. 4, each switching circuit 35 (35 to 1 to 35 n) has two inputs, digital and analog, and an analog drive signal according to these inputs is supplied to the piezoelectric vibrator 37 (37 to 37 n). ). One of the input signal lines of each switching circuit 35 is a digital input signal line 32 representing the state of ink ejection and ejection stop at the nozzle. The digital signal line 32 is connected to an input from the custom IC chip 26 (FIG. 1). Data inputted in series from the custom IC chip 26 is continuously transferred to each shift register 41 (41 to 41-n), latched at a predetermined timing, and inputted to the switching circuit 35.
[0012]
The other input signal line among the input signal lines of each switching circuit 35 is an analog waveform input signal line 36 that is input from the transistor 34 and determines the size of ink particles to be ejected. .
[0013]
In FIG. 5, the voltage waveform analog-converted by the D / A converter IC chip 33 is applied to the piezoelectric vibrator (37-1 to 37n) via the analog switch (35-1 to 35n). It is a circuit diagram for demonstrating the actual condition at the time of being performed. In FIG. 5, only analog signal lines are shown.
[0014]
For example, when the line segment constituting the voltage waveform has an upward gradient (the period from T1 to T2 and the period from T5 to T6 in FIG. 2), the current flows from the power source in the direction of arrow A1 through the NPN transistor. Will be charged and charged. On the other hand, when the line segment constituting the voltage waveform has a downward slope (the period from T3 to T4 and the period from T7 to T8 in FIG. 2), the arrow A2 moves toward the ground via the PNP transistor. Current is discharged in the direction.
[0015]
The current flowing through each transistor during charging and discharging takes a larger value when there is a large voltage displacement in a short time. 2, when the voltage change of the displacement amount delta V occurs during the time t from time T3 to T4, the most current flows through the PNP transistor. The value is proportional to the voltage displacement amount delta V and inversely proportional to the time t. In this way, if a large voltage displacement is applied to the piezoelectric vibrator 37 in a short time, the vibrator 37 causes a large shape change, and thus the ink reservoir 38 is strongly pushed down, and generally large ink particles are ejected. Will be allowed to.
[0016]
As described above, when the piezoelectric vibrator 35 is driven by two transistors, heat generation of the transistors is inevitable. Therefore, as shown in FIG. 3, a considerably large heat sink is attached to the transistor 34.
[0017]
In an actual standard assembly process of an ink jet printer, for example, one head is composed of a total of seven nozzle groups of black, yellow, cyan, magenta, light cyan, light magenta and dark yellow. Then, an ink nozzle driving switching semiconductor element is attached to each nozzle group. For example, in the case of a printer equipped with an ink head composed of 96 nozzles (n = 96) for each color, the switching circuit as described above is included in this ink nozzle driving switching semiconductor element composed of one chip. 96 sets are included. When the ink jet printer is assembled, each chip is attached to each nozzle group.
[0018]
When each of them is driven by one transistor, a voltage is applied to a total of 672 piezoelectric vibrators. Here, the case where all the nozzles for one color (96 nozzles) are discharged will be described as the nozzle operation rate of 100%. That is, when ink is ejected from all 672 nozzles for seven color inks, the nozzle operation rate is 700%.
[0019]
[Problems to be solved by the invention]
When a normal printing operation is performed using the color ink jet printer as described above, it is conceivable that ink is ejected simultaneously from all nozzles in all color heads, that is, the nozzle operation rate is 700%. Absent. For example, even when true color bitmap data, which is often used as a printing sample, is printed, the nozzle operation rate rarely exceeds 130%.
[0020]
However, in the conventional mounting component selection stage, a transistor that can withstand a nozzle operating rate of 700% is employed in case all these nozzles are driven simultaneously. For example, when nozzle cleaning is performed, ink particles are ejected from all nozzles in order to eliminate clogging. Therefore, conventionally, it has been necessary to deal with such exceptional operations.
[0021]
Also, the nozzle operation rate in the image data included in the print command sent from the host computer is generally unpredictable. That is, if black solid printing is performed using all color inks, the nozzle operation rate may easily exceed 200%.
[0022]
Conventional inkjet printers do not have a special function for dealing with such exceptional operations. Therefore, as the number of nozzles increases in the future, it becomes necessary to prepare a transistor capable of passing a very large current for amplifying a trapezoidal wave. Along with this, a very large heat sink must be mounted for transistor cooling. Furthermore, it is conceivable that a plurality of pairs of trapezoidal wave amplification transistors and peripheral circuits must be prepared and dealt with.
[0023]
The present invention has been made in view of the above circumstances. The present invention provides a technique capable of dealing with the above abnormal situation without selecting a transistor component having a special margin or mounting a particularly large heat sink. .
[0024]
[Means for Solving the Problems]
In order to solve the above problems, the print command generation unit of the present invention does not drive the print head to exceed a preset nozzle operating rate. That is, the present invention provides an image processing apparatus including a print command generation unit that transmits a print command including image data, and a print controller of an inkjet printer that receives the print command and executes processing according to the print command. Applied.
[0025]
In the image processing apparatus having the above configuration, the print command generation unit does not include image data that causes a predetermined number or more of the nozzles in the head of the inkjet printer to operate simultaneously in the print command. It is configured as follows.
[0026]
Further, in the above image processing apparatus , the predetermined number is a value of a current consumed by a transistor for amplifying a head driving voltage waveform in a head driving circuit of the ink jet printer. This is the number of drive nozzles when the value corresponds to. According to this configuration, an excessive current exceeding the capacity is not passed through the trapezoidal wave amplification transistor.
[0027]
On the other hand, the ink jet printer of the present invention adopts the following configuration. That is, the present invention includes an image processing unit that receives a print command from a print command generation unit and develops image data included in the command in an image buffer memory in a format in which the image data is mapped to nozzles forming a column, and the image The present invention is applied to an ink jet printer having a drive control unit that discharges ink particles by applying a voltage to an element for driving the nozzle according to data mapped in a buffer memory.
[0028]
In the ink jet printer having the above-described configuration, the current consumption value of the transistor that amplifies the voltage waveform signal for determining the size of the ink particles ejected by the drive control unit is equal to or greater than the maximum allowable current value of the transistor. When the image processing unit performs mapping for the nozzles, the drive control unit distributes the ejection of ink particles based on the data mapped in the image buffer memory to two or more scanning times. It is configured to run.
[0029]
Thereby, the current consumption value of the transistor can be made equal to or less than the maximum allowable current value of the transistor.
[0030]
A program for solving the above problem can be stored and held in a specific recording medium. The recording medium storing the program of the present invention stores a program for realizing the following control contents. That is, this program is a program for causing a central processing unit (CPU) to generate a print command for controlling the printer, and during the print command, during all the nozzles in the head of the printer to be controlled, It is characterized in that it does not include image data for simultaneously operating a predetermined number of nozzles or more.
Further, an image processing method in a print command generation unit for solving the above problems includes a print command generation unit that transmits a print command including image data, and receives the print command and performs processing according to the print command. An image processing method for an image processing apparatus including a print controller of an inkjet printer to execute, wherein the print command generation unit includes a predetermined number or more of all nozzles in the head of the inkjet printer during the print command. Are detected at the same time, the image data is divided, and each of the divided image data is separately transmitted to the print controller.
Further, an image processing method in the drive control unit for solving the above-described problem is a format in which a print command is received from a print command generation unit, and image data included in the command is mapped to nozzles forming a row. An image processing unit developed in the image buffer memory, and a drive control unit that discharges ink particles by applying a voltage to an element for driving the nozzles according to data mapped in the image buffer memory; In an inkjet printer image processing method having
For the number of nozzles such that the current consumption value of the transistor that amplifies the voltage waveform signal for determining the size of the ink particles ejected by the drive control unit is equal to or greater than the maximum allowable current value of the transistor, When detecting that the image processing unit performs mapping,
The drive control unit may perform ejection of ink particles based on data mapped in the image buffer memory in a distributed manner over two or more scans.
[0031]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The invention applies to ink jet printers as already mentioned in the description of the prior art. A characteristic point in the embodiment is a function of the host computer 5 and a function of the print controller 2 in the inkjet printer 1.
[0032]
FIG. 6 is a block diagram showing the contents of the above functions in the printing system of the present invention. In FIG. 6, a print command generation unit 50 is a functional block provided by software such as a printer driver on the host computer 5 side. These software are stored in a recording medium such as a hard disk drive and held by the host computer 5 so as to be executable.
[0033]
The print command generation unit 50 generates image data based on a print request issued by the application program, adds a necessary command, and sends it to the printer. A characteristic point of the print command generation unit 50 according to the embodiment is that the maximum operating rate setting unit 51 is a predetermined one of all nozzles mounted on the print head according to the capability of the hardware (transistor 34) on the printer side. The operation rate of the nozzles is set so that more than the number of nozzles are not operated simultaneously. Further, the image data dividing unit 52 divides image data that exceeds the operating rate and sends it to the printer side.
[0034]
For example, as illustrated in the description of the prior art, a printer 1 having 96 nozzles for each color and having a print head composed of seven colors of ink is connected to the host computer 5 so as to be capable of bidirectional communication. Suppose that On the printer 1 side, the value of the allowable current in the transistor for trapezoidal wave amplification is recorded in, for example, the PROM 24 and managed as the allowable current value storage unit 62.
[0035]
The maximum operating rate setting unit 51 of the host computer 5 acquires, for example, information from the allowable current value storage unit 62 that the nozzle operating rate is 200% at maximum (2/7 of all 672 nozzles). That is, when the printer 1 is assembled, a transistor having a current allowable amount that can drive 192 nozzles at the same time is mounted, and this fact is managed by the allowable current value storage unit. .
[0036]
Here, in the host computer 5, when the application program simultaneously obtains the operation of the number of nozzles exceeding the above 200% (at any timing in the data for one band), the image data dividing unit 52. The image data included in the print command is divided into two bands. That is, data that should be printed in one main scan is printed in two scans.
[0037]
In the above procedure, on the printer 1 side, normal printing may be executed without being aware of the relationship between the nozzle operation rate and the capacity of the trapezoidal wave amplification transistor. When the host computer 5 and the printer 1 are not connected so as to be capable of bidirectional communication, the maximum operating rate setting unit 51 on the host computer 5 side receives information from the allowable current value storage unit 62 on the printer 1 side. I can't get it. In such a case, when the printer driver is incorporated into the host computer 5, a nozzle operating rate that matches the performance of the printer-side hardware (transistor 34) may be set in the maximum operating rate setting unit 51.
[0038]
Next, a configuration for preventing the nozzles exceeding the allowable range from being simultaneously driven by the function of the print controller will be described.
[0039]
Depending on the design of the printer driver used in the host computer 5 and the structure of the operating system itself, the image data may not be divided on the host computer 5 side as described above. Further, in normal print commands, even if data division is performed without any inconvenience, there are cases where it is necessary to separately deal with nozzle driving based on commands. For example, when a cleaning operation for eliminating nozzle clogging is commanded by a command, control for ejecting ink particles is performed on all nozzles. As described above, when the transistor 34 set to the nozzle operating rate of 200% is mounted, if ink particles are ejected from all the nozzles, an excessive current flows through the transistor 34. Become. The configuration of the present embodiment that is effective even in such a case is as described below.
[0040]
The command interpretation unit 61 configured by the CPU 23 and the like passes normal print data to the image processing unit 63. In the image processing unit 63, the image data development unit 64 performs bitmap development on the image buffer 65. Actually, the operation rate calculation unit 67 of the drive control unit 66 that is built in the custom IC chip 26 acquires the aforementioned value of the maximum nozzle operation rate of 200% from the allowable current value storage unit 62. The operation rate calculation unit 67 has a function of counting the bit data developed in the image buffer 65, and when the count value is calculated to be a value exceeding the above operation rate 200%, Then, the nozzle drive distribution unit 68 is instructed to distribute the bit data in the image buffer 65 to a plurality of scans to execute ink ejection.
[0041]
For example, when image data having a nozzle operating rate of 210% is developed in the image buffer 65, the image data is printed in two scans. Further, as described above, when performing a cleaning operation for eliminating nozzle clogging, the bit data developed in the image buffer is data for turning on all 672 nozzles. In this case, Ink droplets are simultaneously ejected to nozzle rows of two colors.
[0042]
By performing the drive control as described above, even if the allowable current value of the transistor 34 is a value of the maximum nozzle operating rate of 200%, it is possible to safely execute the printing and cleaning operations.
[0043]
Although the present embodiment is as described above, any hardware may be used for each function described above. The data number counting function of the operating rate calculation unit 67 may be, for example, a function that uses an existing counter function for measuring ink consumption.
[0044]
FIG. 6 used in the description of the embodiment exemplifies a configuration in which the functions of the present invention are provided on both the host computer side and the printer side. However, these functions are independent of each other. If the function exists in the above, the condition of the present invention is satisfied.
[0045]
【The invention's effect】
According to the printing system of the present invention, a print command including image data exceeding a preset nozzle operating rate, for example, 200%, is not transmitted by a function on the host computer side. Accordingly, an allowable current value of a transistor mounted on the printer and a heat sink for heat dissipation can be used on the premise of a nozzle operating rate of 200%.
[0046]
In the inkjet printer of the present invention, even if the host computer sends image data that exceeds a normal nozzle operation rate, for example, 200%, printing is performed by being distributed from the image buffer to two or more scans. Therefore, a current exceeding the allowable current value of the mounted transistor is not passed.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a hardware configuration of a printing system according to an embodiment.
FIG. 2 is a diagram illustrating an example of a trapezoidal waveform for head driving in the form of a graph.
FIG. 3 is a perspective view illustrating an appearance of a transistor that is an object of drive control.
FIG. 4 is a diagram for explaining how the waveform shown in FIG. 2 is generated by both a digital signal and an analog signal.
5 is a diagram for explaining how the transistor shown in FIG. 3 produces the waveform shown in FIG. 2;
FIG. 6 is a block diagram illustrating functions of the printing system according to the embodiment.
[Explanation of symbols]
1 Printer 2 Printer controller 21 ROM
22 RAM
23 CPU
24 PROM
26 Custom IC chips 27, 28, 32, 36 Signal line 3 Print engine 30 Carriage 31 Head unit 33 D / A converter IC chip 34 Trapezoidal wave amplification transistor 35 1 to 35 n Switching element 37 1 to 37 n Piezoelectric vibrator

Claims (2)

A print command generation unit;
The print command receiving a print command from the generation unit, mapping the image data included in the instruction, and an image processing unit to deploy the image buffer memory in a format that maps to the nozzle of a row, to the image buffer memory A print controller having a drive control unit that discharges ink particles by applying a voltage to an element for driving the nozzle according to the recorded data ;
An inkjet printer comprising:
The current consumption value of the transistor that amplifies the voltage waveform signal for determining the size of the ink particles ejected by the drive control unit is simultaneously applied to a predetermined number of nozzles that exceed the maximum allowable current value of the transistor. When the image data is driven to eject the ink particles, the print command generation unit divides the image data into two or more scans and transmits the divided image data to the print controller. Is based on the image data, and is configured to execute the ejection of the ink particles based on the image data distributed in two or more scanning times so that the predetermined number of nozzles are not driven simultaneously,
The print command generation unit transmits a cleaning operation command to the print controller when the nozzle cleaning operation is performed,
When the print controller is instructed to perform the cleaning operation by the command, the print controller develops data in which all the nozzles are turned on in the image buffer memory, and divides the data into two or more times to eject ink particles. by the inkjet printer, when performing the cleaning operation of the nozzle, so that the predetermined number of nozzles are not driven simultaneously, performing ejection of ink particles divides the nozzle into two or more times,
An inkjet printer characterized by the above. A print command generation unit;
The print command receiving a print command from the generation unit, mapping the image data included in the instruction, and an image processing unit to deploy the image buffer memory in a format that maps to the nozzle of a row, to the image buffer memory following a data, a print controller and a drive controller to I rows ejection of ink particles by applying a voltage to the element for driving the nozzle,
An ink particle ejection method for an inkjet printer having
The current consumption value of the transistor that amplifies the voltage waveform signal for determining the size of the ink particles ejected by the drive control unit is simultaneously applied to a predetermined number of nozzles that exceed the maximum allowable current value of the transistor. When the image data is driven to eject the ink particles, the print command generation unit divides the image data into two or more scans and transmits the divided image data to the print controller. Is based on the image data, and causes the ejection of the ink particles based on the image data to be distributed and executed in two or more scans so that the predetermined number of nozzles are not driven simultaneously,
The print command generation unit transmits a cleaning operation command to the print controller when the nozzle cleaning operation is performed,
When the print controller is instructed to perform the cleaning operation by the command, the print controller develops data in which all the nozzles are turned on in the image buffer memory, and divides the data into two or more times to eject ink particles. by the inkjet printer, when performing the cleaning operation of the nozzle, so that the predetermined number of nozzles are not driven simultaneously, performing ejection of ink particles divides the nozzle into two or more times,
An ink particle ejection method characterized by the above.

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