JP2009083132A - Liquid discharge head and liquid discharge apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid discharge head and liquid discharge apparatus which suppress the variations of discharge quantity of a liquid. <P>SOLUTION: The liquid discharge head is equipped with: a heater containing an exothermic resistance element which generates a heat energy for making the liquid discharged; an insulating film allotted on the heater, an electrode allotted on the insulating film; a capacity measurement part for measuring the capacity which is formed with an electrode allotted on the film, the heater, the insulating film and the electrode; and a discharge quantity correction part for calculating the area of the heater, based on the capacity measured by the capacity measurement part while correcting the discharge quantity of the liquid, based on the measured area of the heater. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid discharge head and a liquid discharge apparatus.

In a liquid discharge head (for example, an ink discharge mechanism) in a liquid discharge apparatus (for example, an ink jet printer), an electric current is supplied to the heater, and the liquid (for example, ink) is heated using heat generated in the heater region. Generate bubbles. Then, by heating and expanding the generated bubbles, the liquid is compressed and discharged.
U.S. Pat. No. 4,723,129 U.S. Pat. No. 4,740,796

  In recent years, there has been an increasing demand for higher image quality in liquid ejection devices. On the other hand, since the liquid discharge head is improved so as to reduce the discharge amount per dot, the size of one dot printed on the recording object can be reduced. As a result, the recording density (resolution) of the print pattern can be increased, and the image quality can be improved.

  However, the amount of liquid discharged may vary due to manufacturing variations in the area of the heater region that heats the liquid discharge head. In this case, since the discharge amount decreases, the variation in the liquid discharge amount due to the manufacturing variation in the area of the heater region becomes conspicuous, and the image quality may be deteriorated.

  On the other hand, in the liquid ejection apparatus, the current supplied to the heater is driven by pulses. The pulse width is preferably the minimum pulse width (discharge critical drive pulse width) at which the liquid is discharged. Supplying this current with the minimum pulse width to the heater reduces the amount of current required to heat the heater, improving energy efficiency and minimizing the stress applied to the heater, so the heater has a long service life. Can be However, the minimum pulse width may vary depending on the thickness of the insulating film formed on the heater to protect the heater. In this case, if the minimum pulse width varies, a current having a pulse width smaller than the actual minimum pulse width may be supplied to the heater, and the heater may not be able to generate heat. As a result, the liquid ejection head may not be able to eject liquid, which may degrade image quality.

  A first object of the present invention is to provide a liquid discharge head and a liquid discharge apparatus capable of suppressing variations in the amount of liquid discharged.

  A second object of the present invention is to provide a liquid discharge head and a liquid discharge apparatus capable of suppressing the influence of the variation in the minimum pulse width of the current required for heating the heater.

  A liquid discharge head according to a first aspect of the present invention includes a heater including a heating resistor element that generates thermal energy for discharging a liquid, an insulating film disposed on the heater, and an insulating film disposed on the insulating film. And determining the area of the heater based on the capacitance measured by the capacitance measuring unit, the capacitance measuring unit for measuring the capacitance formed by the heater, the insulating film, and the electrode. And a discharge amount correction unit that corrects the discharge amount of the liquid based on the area of the heater.

  A liquid discharge head according to a second aspect of the present invention includes a heater including a heating resistance element that generates thermal energy for discharging liquid, an insulating film disposed on the heater, and an insulating film on the insulating film. Determining the thickness of the insulating film based on the capacity measured by the electrode, the capacity measuring unit that measures the capacity formed by the heater, the insulating film, and the electrode; And a pulse width adjusting unit that adjusts a minimum pulse width of a current supplied to the heating resistance element of the heater based on the obtained thickness of the insulating film.

  A liquid ejection apparatus according to a third aspect of the present invention includes the liquid ejection head according to the first aspect or the second aspect of the present invention, and a liquid supply unit that supplies liquid to the liquid ejection head. To do.

  According to the present invention, it is possible to suppress variations in the discharge amount of liquid. Or according to this invention, the influence of the dispersion | variation in the minimum pulse width of the electric current required in order to make a heater generate | occur | produce heat | fever can be suppressed.

  A liquid ejection apparatus 100 according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram illustrating a configuration of a liquid ejection apparatus 100 according to the first embodiment of the present invention.

  The liquid ejection device 100 is, for example, an ink jet printer. The liquid ejection apparatus 100 includes a liquid ejection head 10 and a current supply unit (not shown).

  The liquid discharge head 10 forms an image on a recording object by discharging liquid (for example, ink) onto the recording object (for example, paper).

  The current supply unit supplies current to the heater of the liquid discharge head 10.

  Next, the configuration of the liquid discharge head 10 will be described.

  The liquid discharge head 10 includes a heater 2, an insulating film 4, an electrode 1, an electrode 3, a capacity measurement unit 5, and a discharge amount correction unit 6. In FIG. 1, components other than the capacity measuring unit 5 and the discharge amount correcting unit 6 are shown in a plan view on the upper side of the drawing and a cross-sectional view on the lower side of the drawing.

  The heater 2 includes a heating resistor element that generates thermal energy for discharging the liquid in the heater region Ah. The heating resistor of the heater 2 receives current from the current supply unit and generates thermal energy according to the amount of received current. The width of the heater 2 in the top view is the heater region width W as it is.

  The insulating film 4 is disposed on the heater 2 and protects the heater 2.

  The electrode 1 is disposed on the insulating film 4. As a result, a capacitance (capacitance) Ch is formed by the heater 2, the insulating film 4, and the electrode 1.

  The electrode 3 is disposed between the heater 2 and the insulating film 4 at the left and right ends of the heater 2 in the drawing. Thereby, the electrode 3 defines the heater region length L.

  The capacity measuring unit 5 measures the capacity Ch formed by the heater 2, the insulating film 4, and the electrode 1. Specifically, the capacitance measuring unit 5 is connected to the electrode 1 and measures the capacitance Ch by detecting a physical quantity (for example, a pulse frequency) that changes according to the capacitance Ch.

  The discharge amount correction unit 6 obtains the area S (= W × L) of the heater region Ah based on the capacity measured by the capacity measurement unit 5, and calculates the liquid discharge amount based on the obtained area S of the heater region Ah. to correct.

Specifically, the discharge amount correction unit 6 receives information on the measurement value of the capacity Ch from the capacity measurement unit 5. Further, the discharge amount correction unit 6 acquires information on the relative dielectric constant ε and the thickness d of the insulating film 4 which is set and stored in advance. The discharge amount correction unit 6
S = Ch × d / ε Equation 1
Thus, the area S of the heater region Ah is obtained.

  Then, the discharge amount correction unit 6 refers to a function indicating a relationship (for example, a proportional relationship) between the area of the heater region and the discharge amount of the liquid, as shown in FIG. Based on this function, the discharge amount correction unit 6 obtains the liquid discharge amount Q1 due to the thermal energy generated in the heater region Ah having the area S.

Furthermore, the discharge amount correction unit 6 refers to a function indicating a relationship (for example, a proportional relationship) between the liquid discharge amount and the liquid temperature, as shown in FIG. Based on this function, the discharge amount correction unit 6 obtains the liquid temperature T1 corresponding to the liquid discharge amount Q1. Further, the discharge amount correcting unit 6 obtains the liquid temperature Tt corresponding to the target discharge amount Qt of the liquid based on this function. The discharge amount correction unit 6
ΔTt = T1−Tt Equation 2
Thus, an adjustment amount ΔTt of the temperature of the liquid is obtained. The discharge amount correction unit 6 corrects the liquid discharge amount according to the liquid temperature adjustment amount ΔTt. That is, the discharge amount correction unit 6 corrects the liquid discharge amount by adjusting the temperature of the liquid based on the calculated discharge amount.

  For example, as shown in FIG. 6, the discharge amount correction unit 6 drives the heater 2 so that a heat signal (A) for driving the heater and a heater current (B) linked thereto are supplied to the heater 2. A generator (not shown) and the above-described current supply unit are controlled. That is, current is supplied to the heater 2 for a short period in the period T1 before the period T3 during which liquid is actually ejected (hereinafter referred to as pre-pulse driving). In this pre-pulse drive, the temperature of the liquid is changed without discharging the liquid by passing an electric current through the heater 2 for a short time such that the liquid is not discharged. By adjusting the length of the pre-pulse driving period T1 and the length of the time T2 from the period T1 to the period T3, the liquid temperature can be adjusted, so that the liquid discharge amount can be corrected.

  As described above, since the liquid discharge amount is corrected so as to be a constant target discharge amount, even when there is a manufacturing variation in the area of the heater region, it is possible to prevent the liquid discharge amount from varying.

  Next, an example of a specific configuration of the capacity measuring unit 5 and the discharge amount correcting unit 6 will be described with reference to FIGS. FIG. 2 is a diagram illustrating specific configurations of the capacity measuring unit 5 and the discharge amount correcting unit 6. FIG. 3 is a diagram showing a specific configuration of the oscillation circuit 5a.

  The capacitance measuring unit 5 includes an oscillation circuit 5a and a pulse count circuit 5b. The ejection amount correction unit 6 includes a pre-pulse width modulation circuit 6a.

  For example, as shown in FIG. 3, the oscillation circuit 5a includes a ring oscillator configured by connecting odd-numbered (three in FIG. 4) inverters 5a1, 5a2, 5a3, and 5a4 in series. A capacitor Ch is equivalently connected to the input terminal IN of the oscillation circuit 5a as shown by a broken line. Thereby, the oscillation circuit 5a oscillates at a frequency determined by the inverters 5a1, 5a2, 5a3, 5a4 and the capacitor Ch. That is, the frequency of the pulse oscillated by the oscillation circuit 5a varies depending on the value of the capacitance Ch.

  The inverter 5a4 connected to the subsequent stage of the inverter 5a3 at the final stage of the ring oscillator is a buffer for transmitting a signal to the pulse count circuit 5b at the next stage. If the driving ability of the other inverters 5a1 to 5a3 constituting the ring oscillator is large, the inverter 5a4 is not necessarily provided.

  The pulse count circuit 5b receives the pulse oscillated by the oscillation circuit 5a and counts the frequency of the pulse. The pulse count circuit 5b determines the transmission frequency according to the counted result, and measures the capacitance Ch based on the oscillation frequency.

  The pre-pulse width modulation circuit 6a receives the information on the capacitance Ch from the pulse count circuit 5b, and obtains the liquid temperature adjustment amount ΔTt using the formulas 1 and 2 and the functions of FIGS. Then, the pre-pulse width modulation circuit 6a adjusts the length of the pre-pulse driving period T1 and the length of the time T2 from the period T1 to the period T3 according to the liquid temperature adjustment amount ΔTt. Correct.

  As described above, the liquid discharge amount is corrected so as to be a constant target discharge amount (appropriate amount), so that the liquid discharge amount does not vary even when there is manufacturing variation in the area of the heater region. Can be. Thereby, the dispersion | variation in the discharge amount of a liquid can be suppressed. Moreover, the length measurement at the time of manufacture which was performed conventionally becomes unnecessary, and it leads to a manufacturing cost reduction and a tact increase.

  A liquid ejection apparatus 200 according to a second embodiment of the present invention will be described with reference to FIG. FIG. 7 is a diagram illustrating a configuration of a liquid ejection apparatus 200 according to the second embodiment of the present invention. Below, it demonstrates centering on a different part from 1st Embodiment, and abbreviate | omits description of the same part.

  The liquid ejection apparatus 200 is different from the first embodiment in that it includes a liquid ejection head 210. The liquid ejection head 210 includes a pulse width adjustment unit 207. The pulse width adjusting unit 207 obtains the thickness d of the insulating film 4 based on the capacitance Ch measured by the capacitance measuring unit 5, and determines the thickness d of the insulating film 4 based on the obtained thickness d of the insulating film 4. Adjust the minimum pulse width of the supplied current.

Specifically, the pulse width adjustment unit 207 receives information on the measurement value of the capacitance Ch from the capacitance measurement unit 5. Further, the pulse width adjustment unit 207 obtains information on the area S of the heater region Ah and the relative dielectric constant ε of the insulating film 4 which are set and stored in advance. The pulse width adjustment unit 207 is
d = ε × S / (Ch) Equation 3
Thus, the thickness d of the insulating film 4 is obtained.

  Then, the pulse width adjustment unit 207 refers to a function (not shown) indicating the relationship between the thickness of the insulating film and the minimum pulse width. The minimum pulse width is the minimum pulse width of the current supplied from the current supply unit to the heating resistance element of the heater 2, and is the minimum pulse width of the current necessary for causing the heater 2 to generate heat. The relationship between the thickness of the insulating film and the minimum pulse width is as follows. When the thickness of the insulating film is reduced, the heat of the heater 2 is easily transferred to the liquid, and the minimum pulse width can be shortened. On the contrary, when the thickness of the insulating film is increased, the heat of the heater 2 is not easily transmitted to the ink, and the minimum pulse width needs to be increased.

  Based on this function, the pulse width adjustment unit 207 obtains the minimum pulse width (the length of the period T1 shown in FIG. 6) when the thickness of the insulating film 4 is d. The pulse width adjustment unit 207 controls a drive signal generation unit (not shown) and the above-described current supply unit so that prepulse driving is performed with the obtained minimum pulse width.

  As described above, since the current having the minimum pulse width determined according to the thickness of the insulating film 4 is supplied to the heating resistance element of the heater 2, the current having a pulse width smaller than the actual minimum pulse width is obtained. Can be reduced to the heater. That is, it is possible to reduce problems that occur when the minimum pulse width varies. As a result, it is possible to suppress the influence of the variation in the minimum pulse width of the current necessary for heating the heater.

  In addition, the length measurement at the time of manufacturing and the measurement at the time of shipping are unnecessary, which leads to a reduction in manufacturing cost and a tact increase.

  Next, a recording head which is an example of a specific form of the liquid discharge head will be described. FIG. 8 is a perspective view showing a detailed configuration of a recording head used in the ink jet recording apparatus. Hereinafter, a case where the liquid discharged from the liquid discharge head is ink will be described.

  As shown in FIG. 8, the recording head 810 assembles a flow path wall member 801 for forming a liquid path 805 communicating with a plurality of ejection ports 800 and a top plate 802 having an ink supply port 803. It can be configured as an ink jet recording type recording head. In this case, the ink injected from the ink supply port 803 is stored in the internal common liquid chamber 804 and supplied to each liquid path 805, and the base 808 and the heat generating unit 806 are driven in this state, whereby the ink is discharged from the discharge port 800. Is discharged.

  Also, an ink jet recording apparatus capable of realizing high speed recording and high image quality recording by mounting the recording head 810 shown in FIG. 8 to the ink jet recording apparatus main body and controlling a signal applied from the apparatus main body to the recording head 810 is provided. be able to.

  Next, an ink jet recording apparatus which is an example of a specific form of the liquid ejection apparatus will be described. FIG. 9 is an external perspective view showing an ink jet recording apparatus 900 using the recording head 810 shown in FIG.

  In FIG. 9, a recording head 810 is mounted on a carriage 920 that engages with a spiral groove 921 of a lead screw 904 that rotates via driving force transmission gears 902 and 903 in conjunction with forward and reverse rotation of a driving motor 901. Has been. The recording head 810 can reciprocate in the direction of arrow a or b along the guide 919 together with the carriage 920 by the driving force of the driving motor 901. A paper pressing plate 905 for the recording paper P conveyed on the platen 906 by a recording medium feeding device (not shown) presses the recording paper P against the platen 906 along the carriage movement direction.

  The photocouplers 907 and 908 are home position detecting means for confirming the presence of the lever 909 provided in the carriage 920 in the region where the photocouplers 907 and 908 are provided and switching the rotation direction of the drive motor 901. It is. The support member 910 supports a cap member 911 that caps the entire surface of the recording head 810, and the suction unit 912 sucks the inside of the cap member 911 and performs suction recovery of the recording head 810 through the cap opening 913. The moving member 915 enables the cleaning blade 914 to move in the front-rear direction, and the cleaning blade 914 and the moving member 915 are supported by the main body support plate 916. It goes without saying that the cleaning blade 914 is not limited to the illustrated form, and a known cleaning blade can be applied to this embodiment. The lever 917 is provided to start suction for suction recovery and moves with the movement of the cam 918 engaged with the carriage 920, and the driving force from the drive motor 901 is a known transmission means such as clutch switching. The movement is controlled by. A recording control unit (not shown) that gives a signal to the heat generating unit 806 provided in the recording head 810 and controls driving of each mechanism such as the drive motor 901 is provided on the apparatus main body side.

  The inkjet recording apparatus 900 configured as described above performs recording while the recording head 810 reciprocates over the entire width of the recording paper P with respect to the recording paper P conveyed on the platen 906 by the recording medium feeding device. is there. Since the recording head 810 is manufactured using the ink jet recording head substrate having the circuit structure of each of the embodiments described above, high-precision and high-speed recording is possible.

  Next, the configuration of a control circuit for executing the recording control of the above-described apparatus will be described. FIG. 10 is a block diagram illustrating a configuration of a control circuit of the ink jet recording apparatus 900. In the figure, showing a control circuit, 1700 is an interface for inputting a recording signal, 1701 is an MPU, and 1702 is a program ROM for storing a control program executed by the MPU 1701. Reference numeral 1703 denotes a dynamic RAM for storing various data (such as the recording signal and recording data supplied to the head). Reference numeral 1704 denotes a gate array that controls supply of print data to the print head 1708, and also controls data transfer among the interface 1700, MPU 1701, and RAM 1703. Reference numeral 1710 denotes a carrier motor for conveying the recording head 1708, and 1709 denotes a conveyance motor for conveying the recording paper. Reference numeral 1705 denotes a head driver for driving the head, and reference numerals 1706 and 1707 denote motor drivers for driving the transport motor 1709 and the carrier motor 1710, respectively.

  The operation of the control configuration will be described. When a recording signal enters the interface 1700, the recording signal is converted into recording data for printing between the gate array 1704 and the MPU 1701. The motor drivers 1706 and 1707 are driven, and the recording head is driven in accordance with the recording data sent to the head driver 1705 to perform printing.

  In the above description, an example in which an ink jet recording head substrate is employed in an ink jet recording head has been described. However, the substrate structure according to each of the above embodiments can be applied to, for example, a thermal head substrate. .

  Each of the above-described embodiments brings about an excellent effect when applied to a recording head that employs thermal energy and ejects ink among the ink jet recording methods.

  As the 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 a so-called on-demand type and a continuous type. In particular, in the case of the on-demand type, the electrothermal transducer disposed in correspondence with the sheet or liquid path in which liquid (ink) is held has a rapid response to the recorded information and exceeds the boiling. Apply at least one drive signal that provides a temperature rise. As a result, heat energy is generated in the electrothermal transducer, and the film is boiled on the heat acting surface of the recording head. is there. By the growth and contraction of the bubbles, liquid (ink) is ejected through the ejection opening 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) with particularly excellent response. 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.

  As the configuration of the recording head, in addition to the combination configuration (straight liquid flow path or right-angle liquid flow path) of the discharge port, the liquid path, and the electric-heat converter as disclosed in each of the above specifications, the following Such a configuration is also included in each of the above embodiments. That is, this is a configuration using US Pat. No. 4,558,333 and US Pat. No. 4,459,600 which disclose a configuration in which the heat acting portion is disposed in the bent region. In addition, each of the above embodiments can be configured as a configuration based on Japanese Patent Application Laid-Open No. Sho 123,670, which discloses a configuration in which a common slit is used as a discharge portion of the electrothermal transducer for a plurality of electrothermal transducers Is valid. Each of the above embodiments is also effective as a configuration based on Japanese Patent Laid-Open No. 138461, which discloses a configuration in which an opening that absorbs a pressure wave of thermal energy corresponds to a discharge portion.

  Furthermore, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, any of the configurations disclosed in the above-described specification may be used. The effects described above can be more effectively exhibited. What is disclosed in the above-mentioned specification is a configuration satisfying the length by combining a plurality of recording heads, a configuration as a single recording head formed integrally, or the like.

  As shown in FIG. 11, the ink jet recording head 810 includes a recording head unit 811 having a plurality of ejection ports 800 and an ink container 812 that holds ink to be supplied to the recording head unit 811. The ink container 812 is detachably provided on the recording head unit 811 with the boundary line K as a boundary. The ink jet recording head 810 is provided with an electrical contact (not shown) for receiving an electrical signal from the carriage side when mounted on the recording apparatus shown in FIG. 9, and the heater is driven by this electrical signal. . A fibrous or porous ink absorber is provided in the ink container 812 to hold the ink, and the ink is held by these ink absorbers.

  In contrast, the ink jet recording head 810 shown in FIG. 11 includes a recording head portion 811 and an ink container 812 that are integrally formed.

  Note that the present invention can be applied to a modified or changed embodiment without departing from the spirit of the present invention.

  The present invention can be applied to a system composed of a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), or an apparatus composed of a single device (for example, a copier, a facsimile machine, etc.). May be.

1 is a diagram illustrating a configuration of a liquid ejection apparatus 100 according to a first embodiment of the present invention. The figure which shows the specific structure of the capacity | capacitance measurement part 5 and the discharge amount correction | amendment part 6. FIG. The figure which shows the specific structure of the oscillation circuit 5a. The figure which shows the relationship between the area of a heater area | region, and the discharge amount of a liquid. The figure which shows the relationship between the discharge amount of a liquid, and the temperature of a liquid. The figure for demonstrating prepulse drive. The figure which shows the structure of the liquid discharge apparatus 200 which concerns on 2nd Embodiment of this invention. FIG. 3 is a perspective view showing a detailed configuration of an ink jet recording head. 1 is an external perspective view showing an ink jet recording apparatus. FIG. 3 is a block diagram illustrating a configuration of a control circuit of the ink jet recording apparatus. FIG. 10 is an external perspective view illustrating another embodiment of the ink jet recording head illustrated in FIG. 9.

Explanation of symbols

10,210 Liquid discharge head 100, 200 Liquid discharge device

Claims (4)

A heater including a heating resistor element that generates heat energy in the heater region for discharging liquid;
An insulating film disposed on the heater;
An electrode disposed on the insulating film;
A capacity measuring unit for measuring a capacity formed by the heater, the insulating film, and the electrode;
A discharge amount correction unit that calculates the area of the heater region based on the capacity measured by the capacity measurement unit, and corrects the liquid discharge amount based on the calculated area of the heater region;
A liquid discharge head comprising: The discharge amount correction unit further calculates a liquid discharge amount based on the obtained area of the heater region, and corrects the liquid discharge amount by adjusting the temperature of the liquid based on the calculated discharge amount. The liquid discharge head according to claim 1, wherein the liquid discharge head is a liquid discharge head. A heater including a heating resistor element that generates heat energy in the heater region for discharging liquid;
An insulating film disposed on the heater;
An electrode disposed on the insulating film;
A capacity measuring unit for measuring a capacity formed by the heater, the insulating film, and the electrode;
The thickness of the insulating film is obtained based on the capacitance measured by the capacitance measuring unit, and the minimum pulse width of the current supplied to the heating resistance element of the heater is adjusted based on the obtained thickness of the insulating film. A pulse width adjustment unit to perform,
A liquid discharge head comprising: A liquid discharge head according to any one of claims 1 to 3,
A current supply unit for supplying a current to the heating resistance element of the heater of the liquid discharge head;
A liquid ejection apparatus comprising:

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