JP2004188970A - Recording equipment and controlling method for recording equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress fluctuation of a voltage impressed on each recording element, without enlarging the capacity of a capacitor at an output end, even when a driving load on a recording head sharply changes. <P>SOLUTION: In recording equipment wherein recording is performed by the recording head which has a plurality of recording elements each driven by electric energy and changes the number of the recording elements driven simultaneously, according to recording data, the timing at which the number of the recording elements driven simultaneously increases sharply is detected by a loading transition detecting circuit 38 from serial driving data 37-13 outputted to the recording head on the basis of the recording data, and the electric energy supplied to the recording head is increased earlier than the timing. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a printing apparatus and a control method of the printing apparatus, and more particularly, to a printing head including a plurality of printing elements each driven by electric energy, and changing the number of printing elements driven simultaneously according to print data. The present invention relates to the control of a recording apparatus that performs recording according to the information.

  Recording devices are widely used as information output means of printers, copiers, facsimile machines, etc., and as this type of recording device, a thermal printer or a device such as a character printer, which discharges ink onto a recording medium such as recording paper to print characters, images, etc. There is known an ink jet recording apparatus for recording an image.

  The inkjet recording apparatus performs recording by ejecting ink while moving the recording head that ejects ink relative to the recording medium, and controls the relative speed between the inkjet recording head and the recording medium; The control of the ejection timing and the stability of the power supply to the print head accompanying this are factors that affect the image quality of the print result.

  Ink jet recording apparatuses are roughly classified into so-called serial type and full line type according to the type of the ink jet head used. Among them, the serial method is a method of performing recording by discharging ink while moving (scanning) an ink jet recording head with respect to a recording medium, and is generally widely used because its configuration is simple.

  In addition, a recording head that discharges ink includes a type that discharges ink by the operation of a piezoelectric element, and a type that discharges ink by instantaneously film boiling ink. A recording head of a method in which ink is discharged by boiling a film is configured such that a heater provided in the vicinity of an ink flow path near an ink discharge port is energized to obtain discharge energy by causing the ink in the vicinity of the ink to boil. Is configured.

  Energy for discharging ink is always supplied stably, and uniform ink droplets can be obtained by performing ink discharge under the same conditions. This is a factor in maintaining good recording image quality. is important. However, in the printing operation, the frequency of ink ejection (duty ratio) differs depending on the image data, and thus the number of heaters that are energized simultaneously varies. Therefore, in accordance with the image data to be recorded, the driving conditions change due to the influence of voltage fluctuation due to the difference in current value output from the power supply, difference in voltage drop due to the resistance component of the transmission system, and the like.

  Conventionally, in order to stabilize such driving conditions, measures have been taken to improve the accuracy of the output voltage from the power supply and to make the transmission system as small as possible in loss.

  Next, a DC / DC converter for supplying electric power to the heater of the recording head will be described.

  In order to instantaneously boil ink by energizing the heater as described above, it is necessary to supply a high voltage to the heater. For this reason, in order to generate a voltage higher than the power supply voltage of other circuits, A DC / DC converter is used.

  FIG. 7 is a circuit diagram showing a configuration example of a conventional DC / DC converter and its voltage control circuit. A DC / DC converter input voltage Vin supplied from a power supply unit (not shown) is input to a switching element 201, and a DC output converted by the switching element 201 and the diode 209 is output via a reactor 202, and is recorded as a load. The output voltage VH-b is supplied to the head.

  A capacitor 203 is connected to the input side of the switching element 201, and a capacitor 204 is further connected through an inductance 202. A smoothing circuit 205 is configured by the reactor 202 and the capacitor 204. The output voltage signal VH-b detected from the output terminal of the smoothing circuit 205 is divided by a resistor R1 and a resistor R2 and input to a voltage control circuit 206, and is feedback-controlled by an error amplifier 207 included in the voltage control circuit 206. Is done.

  An output signal from the error amplifier 207 to which the potential divided by the resistors R3 and R4 of the reference voltage Vref and the potential divided by the resistors R1 and R2 of the output voltage VH-b fed back is input is a voltage. An output signal of the control circuit 206, which controls the switching element 201 through the PWM comparator 208 at a constant voltage. The resistor R5 and the capacitor C1 connected between the inverting terminal and the output terminal of the error amplifier 207 are an example of a phase compensation circuit.

  As described above, the output of the DC / DC converter is feedback-controlled so as to supply a stable output voltage regardless of the value of the output current that changes due to the change in the number of nozzles that are simultaneously driven by the recording head serving as the load. .

  In recent years, it has become possible to easily handle color images by increasing the speed of computers and the like, and by increasing the number of pixels of image input devices such as digital cameras and the like, there has been a demand for higher image quality and higher speed for inkjet printers as output devices. Is getting bigger. As an example, the speeding up of the recording operation of an ink jet printer can be achieved by increasing the ejection (drive) frequency and increasing the number of nozzles that are simultaneously driven. By increasing the amount of ink ejected, it is possible to achieve both high image quality and high speed.

  Considering the case where the number of simultaneously driven nozzles is increased to increase the recording speed, the number of nozzles that are actually driven and eject ink out of the nozzles that can be simultaneously driven is considered. Of course, it changes depending on the image to be recorded at that time. For example, when recording a solid black image, it is necessary to simultaneously discharge from all of the dischargeable nozzles. On the other hand, in an image having a low duty ratio such as a ruled line, only a part of the nozzles that simultaneously discharge is sufficient.

  As described above, the recording operation of the ink jet recording head in the serial printer system, that is, the ink ejection is performed by the thermal energy generated by applying a current to the heater.

  Since a current is required for this ink ejection, the required current value increases in proportion to the increase in the number of nozzles ejecting at the same time. Further, in a serial printer, the number of nozzles driven simultaneously is not always constant, but changes sequentially according to print data transmitted to a print head.

  In other words, in an ink jet printer that forms an image, a pattern, a pattern character, and the like on a recording medium according to image data transmitted from an external device, the image data transmitted from the external device ejects ink from a recording head per unit time. The amount of ink discharged per unit time is determined by the amount of ink discharged per unit time.

  That is, the larger the amount of image data, the greater the number of simultaneously driven nozzles and the greater the power consumption of the recording head. Conversely, if the amount of image data per unit time is small, the number of simultaneously driven nozzles is small, and the power consumption of the recording head is reduced. As described above, the amount of current supplied to the recording head by the DC / DC converter is determined in proportion to the number of simultaneously driven nozzles.

  In order to improve the characteristics of voltage control in a DC / DC converter, Japanese Unexamined Patent Publication No. Hei 6-233530 (Patent Document 1) discloses a technique in which a resistor is inserted into an output line to detect a load current, and the response at the time of a sudden load change is improved. Although an improvement method is disclosed, this method is applied to a DC / DC converter that supplies power to an inkjet print head that requires high voltage accuracy because a voltage drop occurs due to a resistor inserted in an output line. It is difficult. Furthermore, since power loss due to the inserted resistor also occurs, power conversion efficiency deteriorates, which is not preferable for a small DC / DC converter.

JP-A-6-233530

  Here, a power supply for supplying power to the recording head will be described. In order to suppress the variation of the output voltage with respect to the variation of the current caused by the variation of the number of nozzles driven simultaneously of the recording head as a load, the value of the steady-state gain K of the voltage feedback control system can be increased. .

  However, if the value of the steady-state gain K is increased, not only the stability at the time of no load is impaired, but also a problem may occur due to the nonlinearity of the PWM control system.

  For the above reason, the value of the steady-state gain K cannot be so large, and the conventional voltage control system cannot sufficiently cope with the instantaneous current fluctuation due to the load fluctuation, and the transient fluctuation characteristic of the output voltage is poor. In other words, a drop in output voltage due to instantaneous current fluctuation is suppressed by a capacitive component represented by an electrolytic capacitor that converts an instantaneous current inserted into an output terminal into an average current.

  The power supply of an inkjet printer that changes the driving conditions of the recording head that ejects ink droplets greatly depending on the image data transmitted from an external device stabilizes the output voltage against all instantaneous load changes including the recording head driving conditions. Need to be designed to supply. However, for the instantaneous current fluctuation that suddenly swings from the no-load state to the rated maximum current value in the specification for driving to perform the full discharge state, the gain K cannot be sufficiently increased. You cannot follow. For this reason, it is designed so that the capacitance of a capacitive component typified by an aluminum electrolytic capacitor or the like inserted at the output end of the voltage supply means is increased to suppress output voltage fluctuation.

  As described above, when the load fluctuates rapidly from the no-load state where no ink is ejected to the maximum load current that ejects all the nozzles of the print head, the potential difference between the reference voltage and the output voltage is used. In the above-described voltage control circuit due to error amplification, the voltage control circuit cannot follow up due to the delay of the constant voltage feedback amount (error voltage amount of the error amplifier) of the DC / DC converter, and the voltage drops below the set voltage. Would. In order to prevent the output voltage from lowering, it is necessary to considerably increase the capacity of the capacitor at the output end, which hinders the miniaturization and thinning of the DC / DC converter.

  Further, as described above, in order to achieve high speed and high image quality, the recording head of the ink jet printer has been increased in length and number of nozzles, and the number of nozzles driven simultaneously tends to increase. This means that the maximum output current value of the load increases, and it is required to suppress a decrease in the output voltage at the time of a sudden change in the load by a method other than increasing the capacitance of the capacitor. The present invention has been made in view of the above circumstances, and is applied to each recording element without increasing the capacitance of the capacitor at the output end even when the driving load of the recording head changes rapidly. An object is to suppress voltage fluctuation.

A recording device as one embodiment of the present invention that achieves the above object is a recording device that performs recording using a recording head having a plurality of recording elements,
Means for inputting recording data;
Conversion means for converting print data into drive data corresponding to the print element,
Transfer means for serially transferring the drive data to the printhead in N-bit units;
Driving means for driving the recording element based on the driving data,
Counting means for counting M bits (N> M) of N-bit drive data transferred first in synchronization with the transfer by the transfer means;
Detecting means for detecting an increase in the count value by the counting means;
Voltage generating means for outputting a voltage for driving the recording element,
When the detecting means detects an increase in the count value, the voltage generating means increases the output voltage before the driving means is driven based on the next transferred drive data.

  That is, according to the present invention, in a printing apparatus that includes a plurality of printing elements each driven by electric energy and performs printing by a printing head that changes the number of printing elements that are driven simultaneously according to print data, Then, the timing at which the number of printing elements driven simultaneously increases significantly is detected, and before this timing, the electric energy supplied to the printing head is increased.

  With this configuration, even if the number of recording elements driven simultaneously increases greatly, the electric energy supplied to the recording head is increased in advance, so that the power supply capacity cannot follow a sudden change in load and the recording is performed. It is possible to prevent the voltage applied to the element from decreasing.

  Therefore, even when the driving load of the recording head changes abruptly, it is possible to suppress the fluctuation of the voltage applied to each recording element without increasing the capacity of the capacitor at the output end.

  The voltage generator has an error amplifier that outputs a control signal in accordance with an error between the reference voltage and the input voltage. When the detector detects an increase in the count value, it changes the value of the reference voltage. Good.

  In this case, it is preferable that the voltage generation means differentiates the signal output in response to the detection by the detection means, and applies the voltage via the time constant circuit and the current addition circuit to the reference voltage.

  The detecting means preferably classifies the count value into at least three levels, and detects an increase in the count value when the count value changes by a predetermined level or more.

  As the recording head, it is preferable to use a recording head that performs recording by discharging ink, and a recording head that includes an electrothermal converter that generates thermal energy to be applied to the ink.

A recording apparatus as another embodiment of the present invention that achieves the above object is a recording apparatus that performs recording using a recording head having a plurality of recording elements,
Means for inputting recording data;
Conversion means for converting print data into drive data corresponding to the print element,
Transfer means for transferring the drive data to the recording head in predetermined bit units;
Driving means for driving the recording element based on the driving data,
First detection means for detecting a power load amount of simultaneously driven printing elements based on the drive data transferred by the transfer means;
Second detection means for detecting an increase in the power load amount;
Voltage generating means for outputting a voltage for driving the recording element,
When the second detecting means detects an increase in the power load, the voltage generating means increases the output voltage before the driving means is driven based on the next transferred drive data.

  The above object of the present invention is also achieved by a control method of a printing apparatus corresponding to the above-described printing apparatus, a computer program for causing a computer to realize the control method of the printing apparatus, and a storage medium storing the computer program.

  According to the present invention, even when the number of printing elements driven simultaneously increases greatly, the electric energy supplied to the printing head is increased in advance, so that the power supply capacity cannot follow a sudden change in load. The voltage applied to the recording element can be prevented from lowering.

  Therefore, even when the driving load of the recording head changes abruptly, it is possible to suppress the fluctuation of the voltage applied to each recording element without increasing the capacity of the capacitor at the output end.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  In the embodiment described below, a printer will be described as an example of a recording apparatus using an inkjet recording method.

  In the present specification, “recording” (sometimes referred to as “printing”) refers not only to forming significant information such as characters and figures, but also to meaningless or insignificant human perception. Regardless of whether or not the image is exposed, a case where an image, a pattern, a pattern, or the like is widely formed on a recording medium or a case where the medium is processed is also described.

  In addition, the term “recording medium” refers to not only paper used in general recording devices, but also a wide range of materials that can accept ink, such as cloth, plastic films, metal plates, glass, ceramics, wood, and leather. Shall be.

  Further, “ink” (sometimes referred to as “liquid”) is to be interpreted broadly as in the definition of “recording (printing)”, and when applied on a recording medium, an image or pattern , A liquid that can be used for forming a pattern or the like, processing a recording medium, or treating ink (for example, coagulation or insolubilization of a colorant in ink applied to a recording medium).

<Mechanical configuration of recording device>
FIG. 8 is a perspective view showing a schematic mechanical configuration of the ink jet recording apparatus according to the present invention.

  Four ink jet recording heads for recording each color, a Bk (black) head 2-1, a Y (yellow) head 2-2, an M (magenta) head 2-3, a C (cyan) head 2-4, and The carriage 3 to which the ink tanks 1-1 to 1-4 integrally attached to the recording head and the optical home position sensor (hereinafter, referred to as HP sensor) 8 are mounted transmits the driving force of the carriage drive motor 5. It is movably attached to a guide shaft 6 connected to a part of the drive belt 4 and arranged in parallel to the scanning direction. The driving force of the carriage drive motor 5 causes the inkjet recording heads 2-1 to 2-1 to move. The sheet reciprocates over the entire width of the recording paper conveyed by a recording medium conveyance mechanism (not shown) on the platen 7 disposed opposite to the ejection surface 2-4. And has a configuration in which the recording to the recording paper.

  In the above-mentioned inkjet recording heads 2-1 to 2-4, a plurality of thin pipe-shaped nozzles for discharging ink are arranged in parallel on a discharge surface facing a recording surface of recording paper, Further, a heater that gives ejection energy to ink supplied from the integrated ink tanks 1-1 to 1-4 is provided near the nozzle.

  The nozzles of the recording heads 2-1 to 2-4 are configured to be arranged in a direction perpendicular to the scanning direction of the carriage 3, and four recording heads are arranged side by side in the scanning direction of the carriage.

  Further, the HP sensor 8 determines the reference position (carriage home position) in the scanning direction of the recording operation by detecting the reference position detecting projection 12 when the carriage 3 moves on the guide shaft 6 in the initial operation. Used to

  The above-described ink jet recording apparatus receives data such as image information and control commands input from an external host device or the like in a recording control unit (not shown) described below, expands the received data into image data of each color, and outputs an image. A series of printing operations are controlled so that the data is transferred to the printing head and the carriage 3 is scanned, and ink is ejected at a required timing.

  The recording controller and the carriage 3 are connected by a flexible cable 13 and receive various signals and supply of power required for ejection.

  Hereinafter, embodiments of the present invention in the ink jet recording apparatus having the above configuration will be described in detail.

  FIG. 1 is a block diagram showing the configuration of the embodiment of the present invention.

  A recording control unit 30 shown in FIG. 1 includes a CPU 31, a ROM 32 and a RAM 33 as storage units, an interface circuit 34 for a host device 41 as an external device, and a motor control circuit that drives the carriage drive motor 5 and the paper feed motor 10. 35 and a gate array 36 made up of a logic circuit that supplements the operation of the CPU 31 and performs each control.

  A head control block 37 for controlling the ejection timing and driving of the inkjet recording head 2 is configured in the gate array 36 described above.

  A stepping motor is used for the carriage drive motor 5. The CPU 31 sends a signal to the carriage drive motor 5 to the motor control circuit 35 to move the carriage 3 and simultaneously manages the number of pulses from the reference position in the scanning direction to determine the current position of the carriage 3. I know.

  When the carriage 3 moves and the mounted recording heads 2-1 to 2-4 reach a place where ink should be ejected, the head control block 37 controls so as to eject ink.

  In the present embodiment, the recording position in the scanning direction is detected by managing the driving pulse of the motor as described above. However, a recording apparatus that detects a carriage position by providing a dedicated encoder is also common.

  The CPU 31 controls the overall operation of the ink jet printing apparatus according to a program stored in the ROM 32 in advance or a control command input from the host device 41 via the interface circuit 34.

  The ROM 32 is loaded with programs for operating the CPU 31, various table data necessary for head control, character data for creating character data, and the like.

  The interface circuit 34 is an interface unit when a control command and control data from the host device 41 to the inkjet recording control are input and output.

  The RAM 33 includes a work area for the operation of the CPU 31 or the like, or a temporary storage area for recording data and control codes input from the host device 41 via the interface circuit 34. The print data is converted into bit data corresponding to the nozzles of the head, and then stored in the print buffer. This print buffer is also configured in the RAM 33.

  The power supply unit 9 supplies the recording control unit 30 with the Vcc voltage for driving the logic, the motor control circuit 35, the VM voltage for driving the paper feed motor 10 and the drive motor 5, and the DC / DC converter 40 via the flexible cable 13. To supply a VH-r voltage for driving the head.

  The load amount transition detection circuit 38 includes a pixel corresponding to the number of nozzles of a print head driven from a serial data signal 37-13 which is a part of a control signal sent from the gate array 36 including the head control block 37 to the head carriage 3. The head drive voltage VH, which is the output voltage of the DC / DC converter 40, is detected by detecting the transition state of a certain number of pixels and transmitting a control signal to the control voltage correction circuit 39 via the flexible cable 13. -B and VH-c are variably controlled.

  Further, the ejection circuit and ejection control of the print head according to the present embodiment will be described in detail with reference to FIGS. FIG. 2 is a circuit diagram showing a detailed configuration of the head control block 37 and the load amount transition detection circuit 38, and FIG. 3 is a circuit diagram showing a detailed configuration of a circuit provided in the head carriage 3. 2 and 3, the control voltage correction circuit 39 is provided in the DC / DC converter 40 of the head carriage 3, but may be provided in a recording control unit on the main body side as a modified example as shown in FIG.

  In the present embodiment, recording is performed using four recording heads. However, since the principle of operation is the same, the Bk head 2-1 will be described.

  The driving procedure of one cycle of the recording operation of the recording head will be described below. The data transfer circuit 37-1 in the head control block 37 sends out a serial data signal 37-13, a clock signal 37-15, and a latch signal 37-14 to send out ejection data to the print head. Each signal is connected to the Bk head 2-1.

  The N-bit serial data signal 37-13 is sequentially stored in the shift register 2-101 formed on the Bk head 2-1 in synchronization with the clock signal 37-15, and ejection is performed for any nozzle among the configured nozzles. Used to choose what to do. When the transmission of the data for the number of nozzles is completed, the latch signal 37-14 is transmitted, the data stored in the shift register 2-101 is moved to the register 2-102, and the data setting ends.

  When the data setting is completed, three block selection signals 37-16 and a heat signal 37-12 are transmitted from the heat timing controller 37-2 in accordance with the position of the carriage 3. In the present embodiment, the nozzles of the same block are arranged every eight nozzles. The block selected by the three block selection signals 37-16 activates the input of the AND circuit 2-104 of the corresponding block by the decoder 2-103 formed on the Bk head 2-1.

  When the heat signal 37-12 is input to the nozzle for which data set and block selection have been performed in accordance with the above procedure, all three inputs of the AND circuit 2-104 become high level, and the nozzle circuit is connected to the corresponding nozzle heater 2-106. The activated drive transistor 2-105 operates, and current flows through the nozzle heater. The heat signal 37-12 is used for controlling the actual energizing time for temperature control and the like.

  By continuing the operations for one cycle described above, a series of printing operations is realized by discharging ink droplets to desired positions.

  Here, the BK data counter 37-4 counts the number of nozzles actually driven from the serial data signal 37-13, and its output is the light load detection circuit 301 of the load amount transition detection circuit 38 and the heavy load detection circuit The circuit 302 and the intermediate load detection circuit 303 are connected.

  In the load amount transition detection circuit 38, the Na counter 313 detects the timing of the upper Na bit of the serial data signal 37-13 transmitted every N bits in synchronization with the latch signal 37-14, and latches it. The signal is transmitted to the circuit 314. For example, if N is 1024 and a is 256, the data in the 768th bit detects the transfer timing. The latch circuit 314 holds a high-level signal until reset by the latch signal 37-15 of the next serial data signal, and outputs a high-level signal to the AND circuit 306 from the Na-th bit to the latch signal after the N-th bit. Send a signal.

  Further, the light load detection circuit 301, the heavy load detection circuit 302, and the intermediate load detection circuit 303 transmit the upper Na bits (the N bits first) of the serial data signal 37-13 transmitted every N bits. (Na bits), the number of simultaneously driven nozzles is detected, and a detection signal is output when the detected number of nozzles is within a detection range preset by each circuit.

  The detection ranges of the light load detection circuit 301, the heavy load detection circuit 302, and the intermediate load detection circuit 303 are the total number of nozzles of the print head, the number of bits of the serial data signal Na to be detected, and the detection range of the DC / DC converter 40. The ratio is set in advance based on the step response capability of the feedback control circuit. The ratio (drive duty) of the number of driven nozzles to the total number of nozzles of the print head is classified into three stages: light load, heavy load, and intermediate load. Then, according to the classification, a signal is output to the DC / DC converter to change the amount of current supplied to the recording head.

  The classification of such drive duties is not limited to three stages as in the present embodiment, but may be configured to be classified into finer multiple stages.

  The light load detection circuit 301 detects from the signal of the BK data counter 37-4 when there is no nozzle ejection information in the upper Na bits of the serial data signal 37-13 or when the nozzle ejection information is extremely small. The signal 301-1 is output to the counter circuit 304. The detection signal 301-1 is counted by the counter circuit 304. When the count value is equal to or more than a predetermined number, that is, when the light load state continues for a set time or more, a high-level signal is output from the latch circuit 305 to the AND circuit 306.

  In the light load detection circuit 301, the number of simultaneously driven nozzles included in the data of the upper Na bits of the serial data signal 37-13 from the signal of the BK data counter 37-4 is equal to or greater than the set value. In this case, the detection signal 301-1 is not output.

  The intermediate load detection circuit 303 determines whether the number of simultaneously driven nozzles included in the data of the upper Na bits of the serial data signal 37-13 from the signal of the BK data counter 37-4 is the light load detection circuit 301 and the heavy load detection circuit. The detection signal 303-1 is output when the detection signal is out of the range detected by the detection circuit 302. When the detection signal is output from the intermediate load detection circuit 303, a reset signal is output to the reset terminals of the counter circuit 304 and the latch circuit 305 connected to the light load detection circuit 301, and the counter circuit 304 and the latch circuit 305 are reset. You.

  The intermediate load detection circuit 303 does not output the detection signal 303-1 when the number of simultaneously output nozzles in the data of the upper Na bits of the serial data signal 37-13 is out of the set range. .

  The heavy load detection circuit 302 determines that the number of simultaneously driven nozzles included in the data of the upper Na bits of the serial data signal 37-13 from the signal of the BK data counter 37-4 is equal to or greater than a predetermined number (for example, The detection signal 302-1 is output when the number is 80% or more of the total number of nozzles.

  The heavy load detection circuit 302 outputs the detection signal 302-1 when the number of simultaneously driven nozzles included in the data of the upper Na bits of the serial data signal 37-13 is equal to or less than the set value. Do not output.

  The AND circuit 306 has three input terminals, and one input terminal receives an output from the latch circuit 305 and goes high when the light load state continues for a set time or more. The output from the heavy load detection circuit 302 is connected to another input terminal via a latch circuit 315. Further, the output from the Na counter 313 is connected to the other input terminal via the latch circuit 314.

  Therefore, the state changes from the light load state to the heavy load state, the timing of the upper Na-th bit of the serial data signal 37-13 having N bits is detected, and the latch circuit 314 outputs a high-level signal. Then, all three inputs of the AND circuit 306 become high level, and the AND circuit 306 outputs a high level signal. The high-level signal output from the AND circuit 306 passes through the latch circuit 307, and is earlier than the N-bit serial data signal 37-13 actually set in the register 2-101 by the time required for transmitting the a-bit. At the timing, it is input to the control voltage correction circuit 39 of the DC / DC converter 40.

  That is, it is possible to detect a transition from a light load state in which the number of simultaneously driven nozzles is extremely small to a heavy load state near full discharge. At this time, it is notified to the control circuit of the DC / DC converter at a timing earlier than the time required for transmission of the a-bit than the actual driving with the heavy load.

  The output of the latch circuit 307 of the load amount transition detecting circuit 38 is input to a differentiating circuit 310 in the control voltage correcting circuit 39 of the DC / DC converter, and the logic signal transmitted from the latch circuit 307 to the control voltage correcting circuit 39 is differentiated. The circuit 310 converts the edge portion of the logic signal into a differential waveform to be extracted.

  Next, the configuration and operation of the DC / DC converter 40 will be described with reference to FIGS. FIG. 4 is a diagram illustrating a detailed configuration of the DC / DC converter according to the present embodiment, and FIG. 5 is a time chart illustrating a state of a signal of each unit of the DC / DC converter.

  As shown in FIG. 4, the output of the load transition detection circuit 38 is input to the differentiation circuit 310 of the control voltage correction circuit 39 in the DC / DC converter 40, and the output of the differentiation circuit 310 is input to the time constant circuit 312. Is done. The output of the time constant circuit 312 is input to the current adding circuit 311.

  Therefore, the pulse-like logic signal output from the load amount transition detection circuit 38 is converted from a pulse waveform to a differential waveform by the differentiating circuit 310. This differentiated waveform signal is input to the current adding circuit 311 after its waveform is dulled by the time constant circuit 312, and is applied to the non-inverting input of the error amplifier 207 with reference to the potential obtained by dividing the reference voltage Vref by the resistors R3 and R4. Applied.

  In FIG. 5, (a) shows the state of the output signal from the load transition detection circuit 38, (b) shows the state of the output signal from the differentiating circuit 310, (c) shows the state of the output signal from the time constant circuit 312, ( d) shows the output voltage waveform from the DC / DC converter 40, and (e) shows the current waveform supplied from the DC / DC converter.

  On the horizontal axis indicating time, t1 is the timing when the transition from the light load state to the heavy load state is detected by the load amount transition detection circuit 38, and t2 indicates the timing at which the heavy load state is actually set. Therefore, the section indicated by A is a light load state, and the section indicated by B is a heavy load state.

  The waveform shown by a broken line in (d) indicates a voltage waveform output from the DC / DC converter when the load amount transition detection circuit 38 and the control voltage correction circuit 39 of the present embodiment are not provided.

  The error amplifier 207 adjusts the ON / OFF timing of the switch element so that the voltage values of the inverting input and the non-inverting input become equal. Therefore, the error amplifier 207 outputs the output voltage VH only by the potential obtained by superimposing the waveform obtained by duplicating the differential waveform by the differentiating circuit 310 and the time constant circuit 312 on the potential obtained by dividing the reference voltage Vref by the resistors R3 and R4. Attempt to control -b in a direction to increase. The control for increasing VH-b is started at a timing earlier than the timing at which the nozzle is driven by the serial data signal 37-13 sent to the register 2-101 in the print head by the time required for transmitting the a bit. Is done.

  This is because the light load detection circuit 301, the heavy load detection circuit 302, and the intermediate load detection circuit 303 in the load amount transition detection circuit 38 detect only the upper Na bits of the N-bit serial data signal 37-13. This is because the Na counter 313 extracts the Na-th bit timing.

  In this way, control is performed to increase the output voltage at a timing earlier than the timing when the serial data signal 37-13 is all stored in the register 2-101 and the actual driving is performed by the time required for transmitting the a-bit, Control is performed to increase the gain K of the feedback control circuit before a sudden load change actually occurs.

  Next, a configuration example of the control voltage correction circuit 39 of the present embodiment will be described with reference to FIG.

  The differentiating circuit 310 includes a capacitor C2 provided at the input stage and a resistor R6. In the example shown in FIG. 6, the inverting amplifier has a two-stage configuration of Q1 and Q2, and the gain can be adjusted by the values of the resistors R6, R7, R8, and R9. The time constant circuit 312 includes a resistor R7 inserted between the inverting terminal and the output terminal of the amplifier Q1, and a capacitor C3 connected in series. Therefore, the ladder-type D / A converter constituted by the resistors R10, R12, R13, and R14 causes the reference potential Vref to be applied to the non-inverting terminal of the error amplifier 207 at the potential divided by the resistors R3 and R4. , A waveform obtained by adding a waveform obtained by dulling the differential waveform by the resistor R7 and the capacitor C3.

  As described above, the time constant circuit 312 adjusts the maximum value of the blunted differential waveform to the timing at which the nozzles of the print head are actually driven, or delays the actual feedback control of the DC / DC converter 40. DC / DC converter with a sudden load change from a light load state where the number of driven nozzles is small to a heavy load state such as full discharge. It is possible to correct the voltage drop in the section where the response of the feedback control of 40 cannot follow.

  In the time chart shown in FIG. 5D, the output voltage rises immediately before the nozzle of the print head is driven. However, if the output voltage does not exceed the upper limit of the output voltage in the specification of the DC / DC converter, there is no particular problem. There is no.

  Although not described in this embodiment, a paper feed motor signal and a drive motor signal are separately lightly loaded as signals for detecting that the recording head has not been driven due to paper feed or initial operation. It may be an input of a detection circuit.

  In the present embodiment, the output voltage of the DC / DC converter is equally supplied to the four print heads. However, two outputs, which are voltages that make the output voltages for the Bk print head and the color print head different, or for each color Even in the case of a multi-output type in which different output voltages are supplied to the recording heads, the load amount transition detection circuit 38 and the control voltage correction circuit 39 are provided in each output voltage or each output voltage control circuit. Similar effects can be obtained.

  Further, in the present embodiment, the two-output DC / DC converter using the BK print head 2-1 and the Y, M, and C color print heads as separate power sources is used. Can be calculated and configured as the same output voltage. Alternatively, a configuration may be employed in which serial data is counted for each recording head and a different output voltage is output for each.

  In the above description, the time from when the upper Nath bit of the serial data signal 37-13 is detected to when the serial data signal 37-13 is stored in the shift register 2-101 is defined as the transmission time of the a bit. It is assumed that the time required is equal to the time required, but it takes into account the time until the nozzle of the print head is actually driven, including the time when the latch signal and the heat signal 37-12 are output to the register 2-104 and the heat signal 37-12 is output. There is a need to. However, there is no problem in implementing the present embodiment as long as the time from when the load amount transition detection circuit detects the transition from the light load to the heavy load until the recording head is actually driven is secured.

[Other embodiments]
The above-described embodiment is directed to an ink jet printing apparatus including a plurality of nozzles as printing elements and heaters provided corresponding to each nozzle, and a printing head that supplies power to and drives the heaters. Although the present invention has been described, the present invention is also applicable to a recording apparatus having a recording head of another type.

  Further, the recording apparatus of the above embodiment is a serial recording apparatus that performs recording by scanning a recording head on a recording medium, but the present invention is also applicable to other types of recording apparatuses that are driven by electric energy. The present invention can be applied to a printing apparatus that includes a plurality of printing elements and performs printing by a printing head that changes the number of printing elements that are driven simultaneously according to print data.

  That is, the present invention can be widely applied to control of a print head including a plurality of print elements each driven by electric energy.

  The present invention can be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), but may be applied to an apparatus (for example, a copying machine, a facsimile machine, etc.) including one device. May be applied.

  Further, an object of the present invention is to provide a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or an apparatus, and a computer (or CPU or MPU) of the system or apparatus to store the storage medium. It is needless to say that the present invention can also be achieved by reading and executing the program code stored in the program.

  In this case, the program code itself read from the storage medium realizes the function of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

  As a storage medium for supplying the program code, for example, a floppy disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, a ROM, and the like can be used.

  When the computer executes the readout program code, not only the functions of the above-described embodiments are realized, but also an OS (Operating System) running on the computer based on the instruction of the program code. It goes without saying that a part or all of the actual processing is performed and the functions of the above-described embodiments are realized by the processing.

  Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. It goes without saying that a CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

It is a block diagram showing the composition of the embodiment of the present invention. FIG. 2 is a circuit diagram illustrating a detailed configuration of a head control block and a load amount transition detection circuit in FIG. 1. FIG. 2 is a circuit diagram illustrating a detailed configuration of a circuit provided in the head carriage of FIG. 1. FIG. 4 is a diagram illustrating a detailed configuration of the DC / DC converter in FIG. 3. 5 is a time chart illustrating a state of a signal of each unit of the DC / DC converter. FIG. 3 is a diagram illustrating a configuration example of a control voltage correction circuit. FIG. 11 is a circuit diagram illustrating a configuration example of a conventional DC / DC converter and a voltage control circuit thereof. FIG. 1 is a perspective view illustrating a schematic mechanical configuration of an inkjet recording apparatus according to the present invention. It is a block diagram showing the structure of the modification of this invention.

Explanation of reference numerals

1-1 to 1-4 Ink tank 2-1 Bk (black) head 2-2 Y (yellow) head 2-3 M (magenta) head 2-4 C (cyan) head 2-101 shift register 2-102 register 2-103 Decoder 2-104 AND Circuit 3 Carriage 4 Driving Belt 5 Carriage Driving Motor 6 Guide Shaft 7 Platen 8 Optical Home Position Sensor 12 Projection for Reference Position Detection 13 Flexible Cable 30 Recording Control Unit 31 CPU
32 ROM
33 RAM
34 Interface Circuit 35 Motor Control Circuit 36 Gate Array 37 Head Control Block 37-1 Data Transfer Circuit 37-2 Heat Timing Controller 37-4 BK Data Counter 37-12 Heat Signal 37-13 Data Signal 37-14 Latch Signal 37-15 Clock signal 37-16 Block selection signal 38 Load amount transition detection circuit 39 Control voltage correction circuit 40 DC / DC converter 41 Host device 201 Switching element 202 Reactor 203, 204 Capacitor 205 Smoothing circuit 206 Voltage control circuit 207 Error amplifier 208 PWM gate drive Circuit 301 Light load detection circuit 302 Heavy load detection circuit 303 Intermediate load detection circuit 304 Counter 305, 307, 314, 315 Latch circuit 306 AND circuit 308 Generating circuit 309 control voltage correction circuit 310 differentiating circuit 311 current addition circuit 312 time-constant circuit 313 N-a counter R1~R5 resistance C1~C3 capacitor Q1~Q3 amplifier Vref reference voltage

Claims (8)

A recording apparatus that performs recording using a recording head having a plurality of recording elements,
Means for inputting recording data;
Conversion means for converting print data into drive data corresponding to the print element,
Transfer means for serially transferring the drive data to the printhead in N-bit units;
Driving means for driving the recording element based on the driving data,
Counting means for counting M bits (N> M) of N-bit drive data transferred first in synchronization with the transfer by the transfer means;
Detecting means for detecting an increase in the count value by the counting means;
Voltage generating means for outputting a voltage for driving the recording element,
The voltage generating means, when the detecting means detects the increase in the count value, increases the output voltage before the driving means is driven based on the next transferred driving data. apparatus.   The voltage generation unit has an error amplifier that outputs a control signal according to an error between a reference voltage and an input voltage, and changes the value of the reference voltage when the detection unit detects an increase in the count value. The recording apparatus according to claim 1, wherein:   3. The voltage generating unit according to claim 2, wherein the voltage generating unit differentiates a signal output in response to the detection by the detecting unit, and applies a voltage via a time constant circuit and a current adding circuit to the reference voltage. Recording device.   2. The recording apparatus according to claim 1, wherein the detection unit classifies the count value into at least three levels, and detects an increase in the count value when the count value changes by a predetermined level or more.   The recording apparatus according to claim 1, wherein the recording head is a recording head that performs recording by discharging ink.   The recording apparatus according to claim 5, wherein the recording head includes an electrothermal transducer that generates thermal energy to be applied to the ink. A recording apparatus that performs recording using a recording head having a plurality of recording elements,
Means for inputting recording data;
Conversion means for converting print data into drive data corresponding to the print element,
Transfer means for transferring the drive data to the recording head in predetermined bit units;
Driving means for driving the recording element based on the driving data,
First detection means for detecting a power load amount of simultaneously driven printing elements based on the drive data transferred by the transfer means;
Second detection means for detecting an increase in the power load amount;
Voltage generating means for outputting a voltage for driving the recording element,
When the second detecting means detects an increase in the power load amount, the voltage generating means increases an output voltage before the driving means is driven based on driving data to be transferred next. Recording device. A control method of a printing apparatus that includes a plurality of printing elements each driven by electric energy and performs printing by a printing head that changes the number of printing elements that are driven simultaneously according to drive data,
A transfer step of sequentially transferring a predetermined amount of drive data to the recording head,
A counting step of counting the number of printing elements driven simultaneously based on the predetermined amount of drive data;
A determination step of determining whether or not the number of simultaneously driven recording elements is significantly increased based on the count value of the previously transferred drive data and the count value of the subsequently transferred drive data;
When it is determined that the number of recording elements that are simultaneously driven is significantly increased, before the driving data to be transferred later is driven by the recording head, an energy increasing step of increasing electric energy supplied to the recording head; A control method for a recording device comprising:

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