JP2005138427A - Driving method of recording head, element board of recording head, recording head, head cartridge, and recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving method of a recording head exhibiting excellent recording characteristics regardless of variation in the resistance of the recording element. <P>SOLUTION: When driving a recording head including an element board provided with a plurality of recording elements and a plurality of driver transistors corresponding to these recording elements, respectively, a resistance representing that of the plurality of recording elements provided on the element board is measured and a reference voltage reflecting the measured resistance is set. A voltage drop due to a parasitic resistance appearing in the power supply line between a common power supply line for supplying a driving power to each of the plurality of recording elements and the plurality of recording elements is compared with its set reference voltage and then driving each of the plurality of driver transistors is controlled based on the comparison results. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a recording head driving method, a recording head circuit board, a recording head, a head cartridge, and a recording apparatus. In particular, for example, recording occurring under various driving conditions in consideration of manufacturing variations in resistance of a recording element. A recording head driving method for recording an image or the like by discharging ink onto a recording medium that performs high-quality recording and improves the durability of the recording head while suppressing variation in energy input to the element, and recording head element The present invention relates to a substrate, a recording head, a head cartridge, and a recording apparatus.

  A recording device having a function such as a printer, a copying machine, a facsimile, or a recording device used as an output device of a multifunction device or a workstation including a computer, a word processor, or the like, uses a recording sheet or a plastic thin plate (for example, OHP) based on image information. Etc.).

  Such a recording apparatus is classified into an ink jet type, a wire dot type, a thermal type, a thermal transfer type, an electrophotographic type, and the like, depending on the recording type employed.

  Among them, an ink jet recording apparatus (hereinafter referred to as an ink jet recording apparatus) performs recording by ejecting ink from a recording head onto a recording medium. The apparatus can be easily downsized and high-definition images can be printed at high speed. Can be recorded without any special processing on plain paper, running costs are low, non-impact method is low noise, and color images using multi-colored ink. Has many advantages, such as being easy to record.

  There are also several methods in the ink jet recording system. One of them is a bubble jet (registered trademark) in which a heating element is mounted in a nozzle, bubbles are generated in the ink by heat, and the foaming energy is used for ink ejection. ) There is a recording method. Here, a recording element that generates thermal energy for ejecting ink can be manufactured using a semiconductor manufacturing process. Therefore, as a recording head using bubble jet technology, (1) a recording element is formed by using a silicon substrate as a base material to form a recording element substrate, and a groove for forming an ink flow path is formed thereon. Products that have a structure in which top plates made of resin, glass, etc., are joined, and (2) high-precision types that have nozzles formed directly on the element substrate by a photolithography process and have no joints. Yes.

  In addition to utilizing the fact that the element substrate is made of a silicon substrate, not only the recording element is configured on the element substrate, but also a driver for driving the recording element and when the recording element is controlled according to the temperature of the recording head. In some cases, a temperature sensor used in the above and a drive control unit thereof are configured on an element substrate.

  FIG. 7 is a block diagram showing a typical example of the structure of a conventional element substrate for an ink jet recording head (see Patent Document 1).

  As shown in FIG. 7, the element substrate 900 is configured to drive a plurality of heating elements (recording elements) 901 arranged in parallel and each heating element 901 that gives thermal energy for ejection to the ink. A power transistor (driver) 902, image data input serially from the outside and a serial clock synchronized therewith are input, and a shift register 904 that inputs image data for each line and a clock for latching A latch circuit 903 that latches image data for one line output from the shift register 904 and transfers the image data in parallel to the power transistor 902 and an output signal of the latch circuit 903 are externally provided corresponding to the power transistor 902. AND gates applied to the power transistor 902 in response to the enable signal 15, input terminals 905 to 912 for inputting the image data and various signals or the like from the outside.

  The element substrate 900 is formed with a sensor monitor 914 such as a temperature sensor for measuring the temperature of the element substrate 900 or a resistance monitor for measuring the resistance value of each heating element 901. A recording head in which such a driver, a temperature sensor, and a drive control unit thereof are configured on an element substrate has been put into practical use, and contributes to improvement of the reliability of the recording head and miniaturization of the apparatus.

  In such a configuration, image data input as a serial signal is converted into a parallel signal by the shift register 904 and output and held by the latch circuit 903 in synchronization with the latching clock. In this state, when a driving pulse signal (an enable signal for the AND gate 915) of the heating element 901 is input via the input terminal, the power transistor 902 is turned on according to the image data, and current is supplied to the corresponding heating element 901. Then, the ink in the liquid flow path (nozzle) is heated, and the ink is ejected as droplets from the ejection port at the tip of the nozzle.

  FIG. 8 is a diagram showing in detail a portion related to the variation of the parasitic resistance in the element substrate for the ink jet recording head shown in FIG.

  Here, the power transistor 902 (in this case, a bipolar transistor but may be a MOS transistor) shown in FIGS. 7 and 8 and a common power supply wiring or GND wiring for driving a plurality of recording elements are provided. In addition to the presence of a parasitic resistance (or constant voltage) component 916 that leads to loss when energy is input to the recording element when a constant power supply voltage is applied by the recording apparatus main body, the heating element 901 is also shown in FIG. Since the voltage generated in the parasitic resistor 916 varies depending on the number of simultaneous driving, the energy applied to the heating element 901 varies as a result.

  Actually, as shown in FIG. 8, the heating element 901 which is a recording element has an absolute resistance value varying from ± 20% to 30% in consideration of mass production due to the difference in film thickness and its distribution in the substrate manufacturing process. Is an unavoidable situation.

  Therefore, the drive elements for driving the recording elements of the inkjet recording head that have been put to practical use have used power transistors mainly from the viewpoint of making the resistance as low as possible. Here, the power transistor 902 behaves as a constant element driving power source and a constant power source having a reverse bias, or an on-resistance. In this case, since the current flowing through the recording element 901 changes due to the resistance variation of the recording element, the energy (power consumption) in the recording element that is input for a certain time greatly varies depending on the resistance value at the time of manufacturing the recording element.

  Therefore, in order to drive the ink jet recording head to stably discharge ink and to drive the recording element so that the power consumption of the recording element is constant in order to achieve the long life of the recording head. To cope with this, the applied pulse width is changed by the resistance of the recording element.

  In recent years, the number of recording elements necessary for increasing the recording speed has increased considerably. At the same time, the uniformity of the energy applied to the recording element due to high definition of recording has been demanded more than before, and as described above, the larger the difference in the number of simultaneous driving of the recording element, The fluctuation range of energy applied to each recording element is increased, and the life of the recording head is shortened. This leads to a failure such as a decrease in recording quality due to energy fluctuation.

Here, as a non-known technique, it is conceivable to control the driver portion so that a constant current flows through each heating element as shown in FIG. 9 as an effective configuration from the viewpoint of making the energy constant. With such a configuration, a constant current always flows through each heating element. Therefore, unless the resistance value fluctuates during use, the resistance value of the heating element × the constant current value without affecting the number of simultaneous driving of the recording elements. The squared energy is supplied and the above problem can be solved. Further, a configuration that keeps the current flowing through the heater constant has also been proposed (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 7-256883 JP 2001-277516 A

  As described above, in the substrate for the recording head, the resistance of the recording element (heating resistor) having the largest resistance component varies by about 20 to 30% due to manufacturing variations. In addition, since the power supply voltage on the recording apparatus main body side is more constant than in the conventional mechanism, the energy applied to the recording element is adjusted by adjusting the pulse width applied to the recording element with respect to the resistance variation of the recording element. As already mentioned, we have dealt with it so that it is constant.

  However, as in the above conventional example, when a constant current is applied to the heating element in order to eliminate the energy variation due to the difference in the number of simultaneous driving of the recording elements, the resistance in the ink jet recording head due to the resistance variation of the recording elements. The power loss will be significantly different.

  FIG. 10 is a diagram showing variations in power loss when the recording element is driven with a constant current.

  In the example shown in FIG. 10, the resistance value of the recording element is about 100Ω, and the voltage generated at both ends of the heating element when a current of 150 mA is applied as a constant current and the manufacturing variation of the heating element (± 20% in this example) ) Is assumed. FIG. 10 shows that when the recording element has the maximum resistance (120Ω), 1 V is necessary for driver voltage control with respect to the voltage across the recording element (18 V). The ratio of energy consumed by other than the recording element when a voltage (19 V) higher by 1 V is applied on the recording apparatus side is shown. It should be noted that the power consumption of the recording element when a constant current is applied varies (1.8 to 2.7 W) depending on the resistance value of the recording element (80 to 120Ω). The input energy is adjusted by changing the pulse width applied to the element.

  FIG. 10 simultaneously shows the pulse width required when the energy is constant.

  According to FIG. 10, when the resistance value of the recording element is 80Ω, about 58% of the power actually applied to the recording element is mainly consumed in the control part (driver part in the substrate for the ink jet recording head) for supplying a constant current. (Power loss). Further, in order to make the energy input to the recording element constant, the applied pulse width is adjusted to 1.25 μs when the resistance of the recording element is 80Ω, and 0.83 μS when the resistance of the recording element is 120Ω, but the ratio is about 1 The difference in loss energy is about 10 times different between the recording element resistance of 80Ω and 120Ω.

  When all of these are consumed in the element substrate for the ink jet recording head, the temperature of the substrate is raised, and the ink discharge amount may be affected.

  FIG. 11 is a diagram showing the relationship between the recording time and the substrate temperature when a constant current is applied to the substrate of the inkjet recording head.

  As can be seen from FIG. 11, when the resistance of the recording element varies, the manner in which the substrate temperature rises also differs.

  FIG. 12 is a diagram illustrating the relationship between the ink temperature and the ink discharge amount.

  As can be seen from FIG. 12, when the ink temperature changes, the ink discharge amount also changes. Since the ink temperature is affected by the substrate temperature, the increase in the substrate temperature affects the ink ejection characteristics.

  Therefore, it is very difficult to provide an ink jet recording head having uniform ink discharge performance because it is unavoidable that a variation of about 20 to 30% occurs in the resistance value of the recording element when the recording head is manufactured. It suggests that there is.

  As described above, when introducing the method of driving the recording element with a constant current in order to eliminate the difference due to the change in the simultaneous driving number of the recording element, the variation in the resistance value of the recording element caused by the manufacturing process of the recording head As a result, not only wasteful energy consumption occurs, but also the characteristics of the temperature change of the head substrate differ in actual recording, and the recording performance of the recording head greatly fluctuates due to changes in ink viscosity and the like depending on the ink temperature. The problem occurs.

  The present invention has been made to solve the above-described problems, and a recording head driving method having excellent recording characteristics irrespective of variations in resistance values of recording elements, an element substrate of the recording head, a recording head, a head cartridge, And a recording apparatus.

  In order to achieve the above object, the recording head driving method of the present invention comprises the following steps.

  That is, a driving method of a recording head including a circuit board provided with a plurality of recording elements and a plurality of driver transistors corresponding to the plurality of recording elements, wherein the plurality of recording elements provided on the circuit board A measuring step of measuring a resistance value representing the resistance value, a setting step of setting a reference voltage reflecting the resistance value measured in the measuring step, and supplying driving power to each of the plurality of recording elements A comparison step of comparing a voltage drop due to a parasitic resistance generated in a power supply line between a common power supply line and each of the plurality of recording elements and the reference voltage, and the plurality of the plurality of the plurality of the plurality of recording elements based on a comparison result in the comparison step And a control step for controlling the driving of each of the driver transistors of the recording head.

  Further, the present invention may be realized by applying the above-described method to the circuit board of the recording head. The substrate has the following configuration.

  That is, a circuit board of a recording head including a plurality of recording elements and a plurality of driver transistors corresponding to the plurality of recording elements, and a resistance having a value representative of the resistance value of the plurality of recording elements A setting circuit for setting a reference voltage used for setting a current value for energizing the plurality of recording elements based on the resistance value; a reference power source for setting a reference voltage by the setting circuit; A comparison circuit for comparing a voltage drop due to a parasitic resistance generated in a common power supply line for supplying driving power to each recording element and a power line between each of the plurality of recording elements and the reference voltage; And a control circuit that controls driving of each of the plurality of driver transistors based on a comparison result in the comparison circuit.

  More specifically, the driver transistor is a MOSFET transistor, and the gate voltage of the MOSFET transistor may be adjusted in the control step.

  In the control step, it is preferable that the gate voltage is controlled to increase until the amount of voltage drop due to the parasitic resistance becomes equal to the reference voltage. It is desirable.

  Further, the recording head is an ink jet recording head, and in this case, the ink jet recording head includes an electrothermal transducer for generating heat energy to be applied to the ink in order to eject the ink using heat energy. It is desirable to have it.

  Furthermore, the present invention may be realized by incorporating the circuit board of the recording head having the above configuration into the recording head.

  Furthermore, the present invention may be realized by a head cartridge including a recording head in which the circuit board of the recording head having the above configuration is incorporated and an ink tank.

  Furthermore, the present invention can be realized by a recording apparatus using the recording head having the above configuration.

  Therefore, according to the present invention, even if there is a variation in the resistance value of the recording element during mass production of the recording head, there is an effect that recording can be performed by applying an optimum current to the recording element.

  Thereby, it is possible to realize high-quality recording with less power loss and excellent recording characteristics.

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

  In this specification, “recording” (sometimes referred to as “printing”) is not only for forming significant information such as characters and figures, but also for human beings visually perceived regardless of significance. Regardless of whether or not it has been manifested, it also represents a case where an image, a pattern, a pattern, or the like is widely formed on a recording medium or the medium is processed.

  “Recording medium” refers not only to paper used in general recording apparatuses but also widely to cloth, plastic film, metal plate, glass, ceramics, wood, leather, and the like that can accept ink. Shall.

  Furthermore, “ink” (sometimes referred to as “liquid”) is to be interpreted broadly in the same way as the definition of “recording (printing)” above. It represents a liquid that can be used for forming a pattern or the like, processing a recording medium, or processing an ink (for example, solidification or insolubilization of a colorant in ink applied to the recording medium).

  Furthermore, unless otherwise specified, the “nozzle” collectively refers to an ejection port or a liquid channel communicating with the ejection port and an element that generates energy used for ink ejection.

  In addition, the “element substrate” used below does not indicate a simple substrate made of a silicon semiconductor but indicates a substrate provided with each element, wiring, and the like. Further, “on the element substrate” not only indicates the element substrate, but also indicates the surface of the element substrate and the inside of the element substrate near the surface.

  In addition, the term “built-in” in the present invention does not simply indicate that separate elements are arranged on the substrate, but the elements are integrally formed on the element substrate by a semiconductor circuit manufacturing process or the like. , Indicating that it is manufactured.

<Description of Inkjet Recording Apparatus (FIG. 1)>
FIG. 1 is an external perspective view showing an outline of the configuration of an ink jet recording apparatus 1 which is a typical embodiment of the present invention.

  As shown in FIG. 1, an ink jet recording apparatus (hereinafter referred to as a recording apparatus) transmits a driving force generated by a carriage motor M1 to a carriage 2 on which a recording head 3 that performs recording by discharging ink according to an ink jet system is mounted. 4, the carriage 2 is reciprocated in the direction of arrow A, and for example, a recording medium P such as recording paper is fed through a paper feeding mechanism 5 and conveyed to a recording position. Recording is performed by ejecting ink onto the recording medium P.

  Further, in order to maintain the state of the recording head 3 satisfactorily, the carriage 2 is moved to the position of the recovery device 10 and the ejection recovery process of the recording head 3 is intermittently performed.

  In addition to mounting the recording head 3 on the carriage 2 of the recording apparatus 1, an ink cartridge 6 for storing ink to be supplied to the recording head 3 is mounted. The ink cartridge 6 is detachable from the carriage 2.

  The recording apparatus 1 shown in FIG. 1 is capable of color recording. For this reason, the carriage 2 contains four inks containing magenta (M), cyan (C), yellow (Y), and black (K) inks, respectively. An ink cartridge is installed. These four ink cartridges are detachable independently.

  Now, the carriage 2 and the recording head 3 can achieve and maintain a required electrical connection by properly contacting the joint surfaces of both members. The recording head 3 applies energy according to a recording signal to selectively eject ink from a plurality of ejection ports for recording. In particular, the recording head 3 of this embodiment employs an ink jet system that ejects ink using thermal energy, and includes an electrothermal transducer to generate thermal energy, which is applied to the electrothermal transducer. Electric energy is converted into thermal energy, and ink is ejected from the ejection port by utilizing pressure changes caused by bubble growth and contraction caused by film boiling caused by applying the thermal energy to the ink. The electrothermal transducer is provided corresponding to each of the ejection ports, and ink is ejected from the corresponding ejection port by applying a pulse voltage to the corresponding electrothermal transducer in accordance with the recording signal.

  As shown in FIG. 1, the carriage 2 is connected to a part of the driving belt 7 of the transmission mechanism 4 that transmits the driving force of the carriage motor M <b> 1, and slides in the direction of arrow A along the guide shaft 13. It is designed to be freely guided and supported. Accordingly, the carriage 2 reciprocates along the guide shaft 13 by forward and reverse rotations of the carriage motor M1. A scale 8 is provided for indicating the absolute position of the carriage 2 along the moving direction of the carriage 2 (the direction of arrow A). In this embodiment, the scale 8 uses a transparent PET film on which black bars are printed at the necessary pitch, one of which is fixed to the chassis 9 and the other is supported by a leaf spring (not shown). Yes.

  Further, the recording apparatus 1 is provided with a platen (not shown) facing the discharge port surface where the discharge port (not shown) of the recording head 3 is formed, and the recording head 3 is driven by the driving force of the carriage motor M1. At the same time as the carriage 2 loaded with is reciprocated, recording is performed over the entire width of the recording medium P conveyed on the platen by giving a recording signal to the recording head 3 and discharging ink.

  Further, in FIG. 1, 14 is a conveyance roller driven by a conveyance motor M2 to convey the recording medium P, 15 is a pinch roller that abuts the recording medium P against the conveyance roller 14 by a spring (not shown), and 16 is a pinch. A pinch roller holder 17 that rotatably supports the roller 15 is a conveyance roller gear fixed to one end of the conveyance roller 14. Then, the transport roller 14 is driven by the rotation of the transport motor M2 transmitted to the transport roller gear 17 through an intermediate gear (not shown).

  Further, reference numeral 20 denotes a discharge roller for discharging the recording medium P on which an image is formed by the recording head 3 to the outside of the recording apparatus, and is driven by transmitting the rotation of the transport motor M2. . The discharge roller 20 abuts on a spur roller (not shown) that presses the recording medium P by a spring (not shown). Reference numeral 22 denotes a spur holder that rotatably supports the spur roller.

  Furthermore, as shown in FIG. 1, the recording apparatus 1 includes a desired position (for example, a home position) outside the reciprocal movement range (outside the recording area) for the recording operation of the carriage 2 on which the recording head 3 is mounted. A recovery device 10 for recovering the ejection failure of the recording head 3 is disposed at a position corresponding to the position).

  The recovery device 10 includes a capping mechanism 11 for capping the ejection port surface of the recording head 3 and a wiping mechanism 12 for cleaning the ejection port surface of the recording head 3, and interlocks with the capping of the ejection port surface by the capping mechanism 11. Ink recovery such as forcibly discharging ink from the discharge port by suction means (suction pump or the like) in the recovery device, thereby removing ink or bubbles having increased viscosity in the ink flow path of the recording head 3 Process.

  Further, when the recording head 3 is not in operation or the like, the ejection port surface of the recording head 3 is capped by the capping mechanism 11 to protect the recording head 3 and to prevent ink evaporation and drying. On the other hand, the wiping mechanism 12 is disposed in the vicinity of the capping mechanism 11 and wipes ink droplets adhering to the ejection port surface of the recording head 3.

  The capping mechanism 11 and the wiping mechanism 12 can keep the ink ejection state of the recording head 3 normal.

<Control Configuration of Inkjet Recording Apparatus (FIG. 2)>
FIG. 2 is a block diagram showing a control configuration of the recording apparatus shown in FIG.

  As shown in FIG. 2, the controller 600 includes an MPU 601, a program corresponding to a control sequence to be described later, a required table, a ROM 602 that stores other fixed data, a carriage motor M1, a conveyance motor M2, and a recording. A special purpose integrated circuit (ASIC) 603 that generates a control signal for controlling the head 3, and a RAM 604, an MPU 601, an ASIC 603, and a RAM 604, which are provided with image data development areas and program execution areas, are connected to each other. A system bus 605 for transferring data, and an A / D converter 606 for inputting analog signals from the sensor group described below, A / D converting them, and supplying digital signals to the MPU 601 and the like.

  In FIG. 2, reference numeral 610 denotes a computer (or a reader for image reading, a digital camera, etc.) serving as a supply source of image data, and is collectively referred to as a host device. Image data, commands, status signals, and the like are transmitted and received between the host apparatus 610 and the recording apparatus 1 via an interface (I / F) 611.

  Further, reference numeral 620 denotes a switch group, which instructs activation of a power switch 621, a print switch 622 for instructing printing start, and a process (recovery process) for maintaining the ink ejection performance of the recording head 3 in a good state. For example, a recovery switch 623 for receiving a command input from the operator. Reference numeral 630 denotes a position sensor 631 such as a photocoupler for detecting the home position h, a temperature sensor 632 provided at an appropriate location of the recording apparatus for detecting the environmental temperature, and the like. It is a sensor group.

  Further, 640 is a carriage motor driver that drives a carriage motor M1 for reciprocating scanning of the carriage 2 in the direction of arrow A, 642 is a conveyance motor driver that drives a conveyance motor M2 for conveying the recording medium P, and 644 is a recording head. 3 is a head driver.

  The ASIC 603 transfers drive data (DATA) of the printing element (ejection heater) to the printing head while directly accessing the storage area of the RAM 602 during printing scanning by the printing head 3.

  FIG. 3 shows a configuration of an ink jet recording head substrate (hereinafter referred to as a substrate) 100, a recording head 3 on which the substrate is mounted, and a portion that affects the energy applied to the recording element in a recording apparatus on which the recording head is mounted. It is a block diagram.

  The apparatus main body is provided with a power source for supplying power to the recording head and the recording element substrate, and a predetermined voltage and current are applied to the element substrate from the power source.

  Therefore, here, the portions that are not changed with respect to the conventional substrate are omitted, and only the portions characteristic to the embodiment to which the present invention is applied are described.

  In FIG. 3, 101 is a recording element (heating resistor), 102 is a switching element (driver) of the recording element including voltage control for allowing a constant current to flow to each recording element, and 103a and 103b are inside the substrate 100. 104a and 104b are parasitic resistances generated in the common wiring in the recording head 3, 105a and 105b are parasitic resistances generated in the common wiring of the recording apparatus, and 107 is a resistance value of the recording element 101 of the substrate 100. In order to reflect this, it is a monitoring resistor formed in the same process as the recording element formation.

  Reference numeral 108 denotes a drive control logic unit for supplying image data sent from the head driver 644 of the printing apparatus for printing via a shift register, a latch, etc., and energy for ink ejection to the printing elements described above. The driver 102 is controlled to be turned on / off based on the drive pulse signal, and a constant current is generated regardless of the voltage drop caused by the parasitic resistance due to the variation in the number of simultaneously driven recording elements based on the resistance value of the monitor resistor 107. The control unit 110 controls the energization of the recording element, and is responsible for the pulse width control of the driving pulse for driving the recording element.

  Further, reference numeral 112 denotes a nonvolatile memory such as an EEPROM, FeRAM, or MRAM that stores setting information such that each recording element has a constant current value determined by reflecting the resistance value of the monitor resistor 107. Head memory. In this embodiment, the voltage generated at both ends of the recording element 101 is optimized based on the information stored in the head memory 112, and the energy loss in the driver 102 is minimized regardless of variations in the manufacturing of the recording element. It can be.

  Reference numeral 111 denotes a setting circuit that sets a constant current based on information read from the head memory 112.

  FIG. 4 is a flowchart showing steps from substrate manufacturing to head manufacturing, mounting of a recording head to a recording device, and recording according to this embodiment.

  First, in step S110, the element substrate 110 is manufactured using a semiconductor manufacturing process. The basic manufacturing process is conventional. However, in this embodiment, on the manufactured substrate 100, the recording element 101, the monitoring resistor 107, the control unit 108, and a setting circuit 111 that sets a constant current value determined according to the resistance value of each recording element. Etc. are built in.

  In step S120 after manufacturing the element substrate, the recording head 3 is manufactured by combining other components. The recording head 3 is equipped with a head memory 112 for storing information for setting a constant current value for each recording element and for determining a time for driving the recording element. After the recording head 3 is completed, in order to determine a constant current value in step S130, the resistance value of the monitor resistor 107 is read. In step S140, the recording elements having manufacturing variations are energized based on the resistance value. The optimum current value to be determined is determined.

  Here, the setting of the current value when the resistance value of the recording element varies will be described.

  FIG. 5 is a diagram showing the setting of the current value when the resistance value of the recording element according to this embodiment varies.

  Here, it is assumed that the same conditions as described in the conventional example, that is, the resistance value of the recording element is about 100Ω and the resistance value varies ± 20% due to manufacturing variations. Further, the constant current value was set such that a voltage (15 V here) obtained by subtracting the maximum fluctuation value (1 V here) of the driver constant current control voltage from the power supply voltage is generated at both ends of the recording element.

  For example, when the resistance value of the recording element is 80Ω, the current at which the voltage across the recording element is 15 V is 188 mA. Therefore, in order to provide the information to the substrate 100 so that the current value is 188 mA, writing is performed in the head memory 112. Similarly, in the case of a substrate having another resistance value, the head memory 112 may be written so as to set an appropriate current according to the table shown in FIG.

  As described above, step S150 is performed.

  Next, the step S160, that is, an example in which a constant current is applied based on information set in the head memory 112 will be described with reference to FIG.

  FIG. 6 is a diagram showing a configuration in which the recording element 101 and a block for driving the recording element are extracted for one bit.

  In FIG. 6, reference numeral 601 denotes a printing element, 602 denotes a MOS transistor driver that changes the on-resistance according to the flowing current to pass a constant current through the printing element (heater) 601, and converges to a desired current, and 603 denotes a substrate 100. An internal recording element driving power supply line, 604 is a GND line, 605 is a minute parasitic resistance generated in a wiring for energizing the recording element 601, and 606 reflects current information set in the head memory 112, that is, recording. A reference power supply that can change the voltage by reflecting the resistance value of the element, and the reference power supply here uses a voltage source of a band gap voltage that does not have fluctuations in the power supply voltage or temperature dependency. Reference numeral 607 denotes an OP amplifier, and reference numeral 608 denotes a gate voltage control unit that supplies a driver driving power supply voltage supplied from the OP amplifier 607 to the driver 602 according to a logic signal from the control unit 108.

  In the circuit having such a configuration, the OP amplifier 607 increases the gate voltage of the driver until the voltage drop generated in the wiring parasitic resistance 605 becomes equal to the reference voltage according to the current flowing individually in each recording element. Control. In addition, the resistance value of the wiring parasitic resistance 605 does not consume energy unlike the recording element (heater), and the temperature does not change sharply, and thus becomes almost constant. Therefore, in order to obtain a current value calculated from the resistance value of the monitor resistor 107, the voltage of the reference power source 606 is changed based on the current information set in the head memory 112, and a constant current is input to the recording element. it can.

  Thus, in this circuit, a constant current is maintained for each printing element by feeding back the current flowing through each printing element and controlling the gate voltage of the driver 602. Further, since the current value can be set so that the voltage controlled by the driver 602 can be minimized, the energy loss caused by supplying a constant current can be made constant and small regardless of the resistance value of the recording element. Can do.

  Naturally, even if a difference occurs due to a change in the number of simultaneous driving of the recording elements due to a voltage drop generated in common by the recording elements due to the parasitic resistances 103a, 103b, 104a, b, 105a, and b shown in FIG. According to the configuration of this embodiment, since the current flowing through each recording element is constant, the energy given to the recording element does not vary. It is only necessary to consider the difference in voltage drop that can occur in these common wirings in advance and set the voltage control range by the driver 602.

  When the above configuration is used, as shown in FIG. 5, even if the resistance value of the recording element varies in the range of 80 to 120Ω, by determining and setting a constant current according to the resistance value of each recording element, The large power loss (58%) on the low resistance side, which has been a problem in the conventional example, is eliminated, and the power loss can be made constant over the entire range of resistance variation.

  Using the recording head with the current value set in this way, the width of the signal pulse for energizing each recording element to supply ink with a substantially constant energy so that ink can be stably discharged next. To decide. In practice, the pulse width may be gradually increased from a certain value to set a stable pulse width.

  As described above, the process of step S160 is executed.

  In FIG. 5, the pulse width for supplying substantially the same energy is shown as an example.

  That is, according to FIG. 5, when the energy input to one recording element is 2.25 μJ, a suitable pulse width is 0.8 μS to 1.2 μS depending on the resistance of the recording element. Here, as can be seen from the value of the energy loss shown in FIG. 5, in the conventional example, the energy loss is 10 times different due to the variation in the resistance value of the recording element. Even if the resistance value varies, the energy loss is constant, and the loss value is also kept to a minimum.

  The pulse width thus determined is stored as pulse width information in the head memory 112 of the recording head 3 in step S170.

  The recording head 3 manufactured and set as described above is mounted on the recording apparatus in step S180, and then the recording apparatus stores the pulse width information stored in the head memory 112 and the image information to be recorded in step S190. Based on this, recording is performed by supplying a recording signal from the head driver 644 to the recording head 3 and the substrate 100.

  Therefore, according to the embodiment described above, based on the value of the monitoring resistance provided in the recording head, the reference voltage of the reference power source used for driving control for driving the recording element is set for each recording head, The reference voltage is compared with the amount of voltage drop caused by the parasitic resistance of each recording element, and the gate voltage of the MOS transistor that drives the recording element is controlled based on the comparison result. The current can be kept constant.

  So far, the configuration in which the current is constant for one recording element has been described.

  The recording head has a plurality of recording elements. By having this configuration for each recording element, the current flowing through each recording element can be kept constant, that is, the energy can be kept constant. Alternatively, it is possible to take the configuration of this case for each printing element that is driven at the same time and share it. Alternatively, as described in Patent Document 2, it is also possible to obtain the effect of the present invention by setting dummy recording elements and selecting a plurality of reference voltages (see FIG. 13). Further, FIG. 14 shows a configuration example in which the voltage at the parasitic resistance portion is compared with FIG. 13 in order to make the current flowing through the recording element constant.

  As described above, stable high-quality recording and a long life of the recording head can be achieved.

  Furthermore, in the above embodiments, the liquid droplets ejected from the recording head have been described as ink, and the liquid stored in the ink tank has been described as ink. However, the storage is limited to ink. It is not a thing. For example, a treatment liquid discharged to the recording medium may be accommodated in the ink tank in order to improve the fixability and water resistance of the recorded image or to improve the image quality.

  The above embodiments include means (for example, an electrothermal converter) that generates thermal energy as energy used for ink ejection, particularly in the ink jet recording system, and changes the state of the ink by the thermal energy. High density and high definition of the recording can be achieved by using the generating method.

  As its typical configuration and principle, for example, those performed using the basic principle disclosed in US Pat. Nos. 4,723,129 and 4,740,796 are preferable. This method can be applied to both the so-called on-demand type and continuous type. In particular, in the case of the on-demand type, it is arranged corresponding to the sheet or liquid path holding the liquid (ink). By applying at least one drive signal corresponding to the recorded information and giving a rapid temperature rise exceeding nucleate boiling to the electrothermal transducer, the thermal energy is generated in the electrothermal transducer, and the recording head This is effective because film boiling occurs on the heat acting surface of the liquid, and as a result, bubbles in the liquid (ink) corresponding to the drive signal on a one-to-one basis can be formed. By the growth and contraction of the bubbles, liquid (ink) is ejected through the ejection port to form at least one droplet. It is more preferable that the drive signal has a pulse shape, since the bubble growth and contraction is performed immediately and appropriately, and thus it is possible to achieve discharge of a liquid (ink) having particularly excellent responsiveness.

  As this pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further excellent recording can be performed by employing the conditions described in US Pat. No. 4,313,124 of the invention relating to the temperature rise rate of the heat acting surface.

  Further, although the above embodiment is a serial type recording apparatus that performs recording by scanning the recording head, it is a full line type recording apparatus using a recording head having a length corresponding to the width of the recording medium. May be. As a full-line type recording head, either a configuration satisfying the length by a combination of a plurality of recording heads as disclosed in the above-mentioned specification, or a configuration as a single recording head formed integrally. But you can.

  In addition to the cartridge type recording head in which the ink tank is integrally provided in the recording head itself described in the above embodiment, it can be electrically connected to the apparatus body by being mounted on the apparatus body. A replaceable chip type recording head that can supply ink from the apparatus main body may be used.

  In addition, it is preferable to add recovery means, preliminary means, and the like for the recording head to the configuration of the recording apparatus described above because the recording operation can be further stabilized. Specific examples thereof include a capping unit for the recording head, a cleaning unit, a pressurizing or sucking unit, an electrothermal converter, a heating element different from this, or a preheating unit using a combination thereof. In addition, it is effective to provide a preliminary ejection mode for performing ejection different from recording in order to perform stable recording.

  Further, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but the recording head may be integrated or may be a combination of a plurality of colors. An apparatus having at least one of full colors can also be provided.

1 is an external perspective view showing an outline of a configuration of an inkjet recording apparatus 1 that is a typical embodiment of the present invention. FIG. 2 is a block diagram illustrating a control configuration of the recording apparatus illustrated in FIG. 1. FIG. 2 is a block diagram illustrating a configuration of an ink jet recording head substrate, a recording head on which the substrate is mounted, and a portion that affects energy applied to a recording element in a recording apparatus on which the recording head is mounted. 3 is a flowchart showing steps from substrate manufacture to head manufacture, recording head mounting of a recording device, and recording. FIG. 6 is a diagram illustrating setting of a current value when a resistance value of a recording element varies. It is a figure which shows the structure which extracted the block for driving the recording element 101 and a recording element for 1 bit. It is a block diagram which shows the typical example of a structure of the board | substrate for the conventional inkjet recording head. It is a figure which shows in detail the part related to the fluctuation | variation of a parasitic resistance in the board | substrate for inkjet recording heads shown in FIG. It is a figure which shows the structure which controls a driver part so that a fixed electric current may flow through each heat generating body. It is a figure which shows the dispersion | variation in the power loss at the time of driving a recording element with a fixed electric current. It is a figure which shows the relationship between recording time at the time of supplying a fixed electric current to the board | substrate of an inkjet recording head, and board | substrate temperature. It is a figure which shows the relationship between ink temperature and an ink discharge amount. It is a figure which shows the circuit structure in the board | substrate for recording heads of another Example. It is a figure which shows the circuit structure in the board | substrate for recording heads of another Example.

Explanation of symbols

3 Recording head 100 Substrate 101 Recording element (heating element)
102 Recording element switching element (driver)
103a, b, 104a, b, 105a, b Parasitic resistance 107 Monitoring resistor 108 Control unit 110 Drive control logic unit 111 Setting circuit 112 Head memory 601 Recording element 602 MOS driver 603 Drive power supply line 604 GND line 605 Wiring parasitic resistance 606 Reference Power supply 607 OP amplifier 608 Gate voltage control unit 644 Head driver

Claims (11)

A driving method of a recording head including an element substrate including a plurality of recording elements and a plurality of driver transistors corresponding to the plurality of recording elements,
A measuring step of measuring a resistance value representative of the resistance value of the plurality of recording elements provided on the element substrate;
A setting step for setting a reference voltage reflecting the resistance value measured in the measurement step;
A comparison step of comparing the reference voltage with the voltage of the power supply line between each of the plurality of recording elements and a common power supply line that supplies driving power to each of the plurality of recording elements;
And a control step of controlling driving of each of the plurality of driver transistors based on a comparison result in the comparison step.   2. The method for driving a recording head according to claim 1, wherein the driver transistor is a MOSFET transistor, and the gate voltage of the MOSFET transistor is adjusted in the control step. The control step includes
2. The recording head driving method according to claim 1, wherein the gate voltage is controlled to increase so that a voltage drop amount due to the parasitic resistance is equal to the reference voltage. An element substrate of a recording head comprising a plurality of recording elements and a plurality of driver transistors corresponding to the plurality of recording elements,
A resistor having a value representative of the resistance value of the plurality of recording elements;
A setting circuit for setting a reference voltage used for setting a current value for energizing the plurality of recording elements based on the resistance value;
A reference power source in which a reference voltage is set by the setting circuit;
A comparison circuit that compares the reference voltage with a common power supply line that supplies driving power to each of the plurality of recording elements and a voltage of a power supply line between each of the plurality of recording elements;
And a control circuit for controlling driving of each of the plurality of driver transistors based on a comparison result in the comparison circuit. The driver transistor is a MOSFET transistor;
5. The element substrate of a recording head according to claim 4, wherein the control circuit adjusts a gate voltage of the MOSFET transistor.   5. The print head element substrate according to claim 4, wherein the control circuit controls the gate voltage to increase until a voltage drop amount due to the parasitic resistance becomes equal to the reference voltage.   A recording head using the element substrate of the recording head according to claim 4.   The recording head according to claim 7, wherein the recording head is an ink jet recording head.   9. The recording head according to claim 8, wherein the inkjet recording head includes an electrothermal transducer for generating thermal energy to be applied to the ink in order to eject the ink using thermal energy. .   A recording apparatus using the recording head according to claim 7. A head cartridge comprising: a recording head using the element substrate of the recording head according to claim 4; and an ink tank.

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