JP2008149496A - Head substrate, recording head, head cartridge, and recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a head substrate in which temperature variation due to heat generation of every recording element can be detected without increasing the area of the head substrate significantly. <P>SOLUTION: A switching element (MOS transistor) constituting a temperature sensor provided for every recording element is made to function by utilizing a control signal of a drive element (MOS transistor) for driving the recording element and a common signal. These MOS transistors are arranged in proximity to each other on a head substrate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a head substrate, a recording head, a head cartridge, and a recording apparatus. The present invention particularly relates to, for example, a head substrate provided with a temperature detection circuit, a recording head using the head substrate, a head cartridge using the recording head, and a recording apparatus.

  In a printer using an ink jet recording head that records an image by ejecting ink, if the size of the ejected ink droplets is not uniform, the quality of the recorded image is degraded or the image quality is deteriorated due to uneven density, etc. May occur. For this reason, in order to perform high-quality recording, it is desirable to keep the ink droplet size constant.

  In a recording head that employs a system in which ink is heated and foamed and the ink is ejected by the pressure of the ink jet recording head, the size of the ink droplet is affected by the viscosity of the ink and the pressure at the time of foaming. Since the viscosity of the ink and the pressure at the time of foaming depend on the temperature of the ink, the size of the ink droplet changes when the temperature of the ink changes. As a result, the recording image quality deteriorates due to the temperature change of the ink.

  For this reason, conventionally, the temperature of the ink droplet is detected, the pulse width of the current supplied to the heater is changed according to the ink temperature, and the foaming energy is controlled to keep the ink droplet size constant. It was. In addition, control is performed to detect an abnormal temperature rise that causes the recording head to break during ink out or high-speed recording operation, and to stop the recording operation.

  For example, Patent Document 1 proposes a temperature detection means for performing such control. According to this document, temperature detection is performed by a diode built in a semiconductor substrate in which a heater of a recording head is built. Since the forward voltage (VF) of the diode has a temperature dependence characteristic of about −2 mV / ° C., the temperature of the recording head is detected by detecting this voltage change.

  FIG. 8 is a diagram showing the configuration of a recording head temperature detection circuit of a printer equipped with a conventional ink jet recording head.

  In this circuit, a current (If) is applied to the diode 202 provided in the recording head 201 by the current circuit 203 and the amplifier circuit provided outside the recording head, and the forward voltage of the diode 202 is passed through the differential amplifier 204. Amplify and correct. The output voltage from the diode 202 is input from an input terminal 209 to an A / D conversion circuit (not shown) of the CPU 206 of the printer main body. At this time, the temperature of the recording head 201 is detected from the change between the output signal line 211 from the CPU 206 and the voltage output to the comparator 205 via the D / A converter 208.

Note that the temperature inside the printer is input to the CPU 206 via another input terminal 210 by another sensor 207.
JP-A-6-336071

  However, the above-described conventional ink jet recording head (hereinafter referred to as recording head) has only one or several temperature detecting elements on the head substrate, and can only detect the average temperature of the entire head substrate. For this reason, it was impossible to detect abnormal temperature changes in individual heaters caused by heater disconnection, nozzle clogging, or the like. In addition, when detecting the heat generated by each heater, it is necessary to provide a plurality of temperature detection elements and to provide a new circuit or pad for individually reading the detection results. For this reason, there is a problem that the area of the head substrate increases, and as a result, the cost of the head substrate increases.

  The present invention has been made in view of the above conventional example, and an object of the present invention is to provide a head substrate capable of detecting heat generation in each heater without greatly increasing the head substrate area. Another object of the present invention is to provide a recording head, a head cartridge, and a recording apparatus using the head substrate.

  In order to achieve the above object, the head substrate of the present invention has the following configuration.

  That is, a head substrate including a plurality of heaters and a plurality of drive elements that drive the plurality of heaters, a plurality of temperature detection elements provided corresponding to each of the plurality of heaters, and the plurality of the plurality of heaters And an output circuit for outputting a signal from the temperature detection element in accordance with a drive signal for driving the heater.

  According to another invention, a recording head using the head substrate having the above-described configuration is provided.

  According to another aspect of the invention, a head cartridge is provided in which the recording head and an ink tank that stores ink to be supplied to the recording head are integrated.

  According to still another aspect of the invention, a recording apparatus including the recording head or the head cartridge is provided.

  Therefore, according to the present invention, it is possible to detect the temperature of each recording element without providing a complicated circuit. In addition, since the drive signal of the temperature detection element for detecting the temperature of the print element is shared with the drive signal of the drive element that drives the print element, no special signal or circuit is required. Increase can be suppressed as much as possible. This also contributes to the downsizing of the recording head.

  In this way, by detecting a recording element that causes an abnormal temperature change due to a recording failure, for example, it is possible to execute an alternative process such as interpolation recording, and it is possible to prevent degradation of the recorded image quality. It becomes. In addition, by detecting the temperature rise characteristics of the individual recording elements, it is possible to input appropriate energy for recording to the recording elements. This contributes to realizing stable recording and improving the durability of the recording element.

  Hereinafter, preferred embodiments of the present invention will be described more specifically and in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the already demonstrated part and duplication description is abbreviate | omitted.

  In this specification, “recording” (sometimes referred to as “printing”) is not limited to the case of forming significant information such as characters and graphics, but may be significant. It also represents the case where an image, a pattern, a pattern, etc. are widely formed on a recording medium, or the medium is processed, regardless of whether it is manifested so that humans can perceive it visually. .

  “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.

  Further, “ink” (sometimes referred to as “liquid”) should be interpreted widely as in the definition of “recording (printing)”. Therefore, by being applied on the recording medium, it is used for formation of images, patterns, patterns, etc., processing of the recording medium, or ink processing (for example, solidification or insolubilization of the colorant in the ink applied to the recording medium). It shall represent a liquid that can be made.

  Furthermore, unless otherwise specified, the recording element is a generic term for an ejection port, a liquid path communicating with the ejection port, and an element that generates energy used for ink ejection.

  The recording head substrate (head substrate) used below does not indicate a simple substrate made of a silicon semiconductor but indicates a configuration in which each element, wiring, and the like are provided.

  Further, the term “on the substrate” means not only the element substrate but also the surface of the element substrate and the inside of the element substrate near the surface. The term “built-in” as used in the present invention is not a word indicating that each separate element is simply arranged separately on the surface of the substrate. It shows that it is integrally formed and manufactured on top.

<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) includes a recording head 3 that performs recording by ejecting ink according to an ink jet system, and moves the carriage 2 back and forth in the direction of arrow A. To record. At the time of recording, for example, a recording medium P such as recording paper is fed through the paper feeding mechanism 5 and conveyed to a recording position, and recording is performed by ejecting ink from the recording head 3 to the recording medium P at the recording position. Do.

  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.

  The recording head 3 of this embodiment employs an ink jet system that ejects ink using thermal energy. For this reason, the recording head 3 includes an electrothermal transducer as a recording element in order to generate thermal energy. 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.

<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 ROM 602, a special purpose integrated circuit (ASIC) 603, a RAM 604, a system bus 605, an A / D converter 606, and the like. Here, the ROM 602 stores a program corresponding to a control sequence to be described later, a required table, and other fixed data. The ASIC 603 generates control signals for controlling the carriage motor M1, the transport motor M2, and the recording head 3. The RAM 604 is used as a development area for image data, a work area for program execution, and the like. A system bus 605 connects the MPU 601, the ASIC 603, and the RAM 604 to each other to exchange data. The A / D converter 606 inputs analog signals from the sensor group described below, performs A / D conversion, and supplies a digital signal to the MPU 601.

  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. This image data is input in a raster format, for example.

  Reference numeral 620 denotes a switch group, which includes a power switch 621, a print switch 622, a recovery switch 623, and the like.

  Reference numeral 630 denotes a sensor group for detecting the apparatus state, and includes a position sensor 631, a temperature sensor 632, and the like.

  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, and 642 is a conveyance motor driver that drives a conveyance motor M2 for conveying the recording medium P.

  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 604 during printing scanning by the printing head 3.

  The configuration shown in FIG. 1 is a configuration in which the ink cartridge 6 and the recording head 3 can be separated, but a replaceable head cartridge may be configured by integrally forming them.

  FIG. 3 is an external perspective view showing a configuration of a head cartridge IJC in which an ink tank and a recording head are integrally formed. In FIG. 3, a dotted line K is a boundary line between the ink tank IT and the recording head IJH. The head cartridge IJC is provided with an electrode (not shown) for receiving an electrical signal supplied from the carriage 2 when it is mounted on the carriage 2, and the recording head IJH as described above is provided by this electrical signal. Is driven to eject ink.

  In FIG. 3, reference numeral 500 denotes an ink discharge port array. The ink tank IT is provided with a fibrous or porous ink absorber to hold ink.

  FIG. 4 is a circuit diagram showing a configuration of a temperature detection circuit built on the head substrate of the recording head.

  As shown in FIG. 4, a plurality of recording elements (heaters) 101 for heating and foaming ink between two common power supply lines 103 and 104 and ejecting ink from nozzles and the recording elements are driven. The driving elements (MOS transistors) 102 are connected in series. A control signal is input from the control circuit 105 to the gate of the MOS transistor 102 based on information from the recording apparatus main body, and the transistor is turned on / off.

  In the vicinity of each recording element 101, a temperature detecting element (diode) 106 is arranged. A switching element (MOS transistor) 107 serving as an output circuit for outputting a signal from the temperature detection element is connected in series with the temperature detection element 106. The temperature detection element (diode) 106 and the MOS transistor 107 connected in series are connected to common temperature detection output wirings 108 and 109, respectively. A detection signal control circuit 110 is connected to the gate of the MOS transistor 107, and a control signal for a MOS transistor that drives a heater corresponding to the temperature detection element is input to the detection signal control circuit 110.

  The detection signal control circuit 110 generates a signal for designating the output timing of the signal from the temperature detection element as a control signal for driving the MOS transistor.

  The temperature detection output wirings 108 and 109 are connected to a constant current source 112 that applies a constant current provided inside or outside the head substrate and a voltage detection circuit 113 that detects a potential difference between the common wirings.

  Hereinafter, the operation of the temperature detection circuit will be described.

  Among the plurality of recording elements (heaters) 101, an arbitrary recording element (heater) to be detected is selected using a drive signal output from the control circuit. In the selected recording element (heater), the MOS transistor 102 is turned on for a desired time by the drive signal. As a result, an electric current is applied to the recording element (heater), and the ink on the heater is heated and foamed to eject ink droplets.

  When the recording element (heater) is energized and heated, the temperature of the temperature detection element (diode) 106 disposed in the vicinity of the recording element (heater) also rises in response to the heating of the recording element (heater). On the other hand, the gate of the MOS transistor 102 for driving the recording element (heater) 101 and the gate of the MOS transistor 107 connected in series to the temperature detection element (diode) 106 arranged in the vicinity of the recording element (heater) are a detection signal control circuit. 110 is connected.

  FIG. 5 is a diagram illustrating an example of the timing of the drive signal for driving the heater and the output signal (detection signal) of the detection signal control circuit 110. The example shown in FIG. 5A shows that a detection pulse is generated after a certain time delay from the rise of the heater drive pulse. On the other hand, the example shown in FIG. 5B shows that the detection pulse after a certain delay falls after the heater driving pulse falls. In synchronization with (in response to) a pulse for applying a current to the recording element (heater) 101, the MOS transistor 107 connected in series with the temperature detection element (diode) 106 is also turned on.

  Thus, in this embodiment, the output timing of the signal from the detection element is adjusted by the detection signal control circuit in accordance with the drive signal for driving the heater. The detection signal control circuit has a circuit for delaying detection timing and a circuit for setting a detection period in response to a drive signal for driving the heater.

  During this detection operation, only one of the plurality of recording elements (heaters) is selected. For this reason, among the plurality of MOS transistors 107 connected to the temperature detection output wirings 108 and 109, the MOS transistor 107 connected in series to the temperature detection element (diode) 106 arranged in the vicinity of the recording element to be detected. Only “on”. At this time, a constant current is applied from the constant current source 112 connected to the temperature detection output wires 108 and 109 to the temperature detection element (diode) 106 through the MOS transistor 107 which is “ON”. As a result, a forward voltage (Vf) of the diode is generated at both ends of the temperature detection element (diode) 106.

  At this time, if the forward voltage (Vf) is sufficiently large with respect to the voltage drop between the source and the drain of the MOS transistor, the voltage generated between the temperature detection output wirings 108 and 109 is measured to measure the forward voltage generated by the diode. The direction voltage (Vf) can be detected. Since the forward voltage (Vf) of the diode causes a voltage change of −2 mV / ° C. with respect to the temperature change as described above, the temperature in the vicinity of the selected heater is measured by measuring the voltage change between the output wirings. Changes can be detected. By sequentially performing this operation on other recording elements (heaters), it is possible to detect temperature changes due to driving of the recording elements (heaters) for all the individual recording elements (heaters).

  FIG. 6 shows the layout of the head substrate.

  This layout shows an example in which two systems of temperature detection circuits shown in FIG.

  In the layout configuration shown in FIG. 6, ink is supplied from the lower surface of the head substrate to the recording element (heater) 101 disposed on the upper surface of the head substrate through the ink supply port 120 opened in the center of the head substrate. . Then, the recording element (heater) 101 is driven / heated by the driving element 102, whereby the ink on the recording element (heater) is foamed and ejected from nozzles (not shown) formed on the upper surface of the head substrate.

  As shown in FIG. 6, the temperature detection element 106, the switching element 107, and the temperature detection output wirings 108 and 109 are disposed between the recording element 101 and the drive element 102. The temperature detection output wirings 108 and 109 are connected to the input / output pad unit 111 disposed at the end of the head substrate 100, and output temperature detection information to the outside of the head substrate.

  As described with reference to FIG. 4, the gate of the drive element 102 of the recording element (heater) 101 that performs temperature detection and the gate of the switching element 107 are connected via the detection signal control circuit 110. Therefore, as shown in FIG. 6, by arranging these elements adjacent to each other, the wirings connecting the gates can be connected in the shortest time, and the circuit can be efficiently laid out on the substrate.

  Therefore, according to the embodiment described above, although the area for arranging the temperature detection element and the switching element provided for each recording element is increased as compared with the area of the conventional head substrate, other circuits related to temperature detection are particularly provided. do not need. Accordingly, it is possible to detect the temperature of each recording element (heater) while minimizing an increase in the head substrate area.

<Other embodiments>
FIG. 7 is a circuit diagram showing a configuration of a temperature detection circuit according to another embodiment.

  In FIG. 7, the same components as those already described in FIG. 5 are denoted by the same reference numerals, and the description thereof is omitted.

  As can be seen from a comparison between FIG. 4 and FIG. 7, the temperature detecting element 106 is not provided in this embodiment. In this embodiment, the switching element 107a has both functions of temperature detection and switching. That is, temperature detection is performed using the temperature characteristics when the switching element is “on”.

  In this embodiment, a MOS transistor is used as the switching element 107a, and the temperature change of the on-resistance value of the MOS transistor is used for temperature detection. Since the on-resistance of the MOS transistor normally has a temperature characteristic of several thousand ppm / ° C., it is possible to detect the temperature in the vicinity of the heater as in the above-described embodiment by detecting the temperature change of this resistance value. .

  According to this embodiment, it is not necessary to provide the temperature detecting element 106 as compared with the above-described embodiment, so that the area of the head substrate can be further reduced as compared with the layout configuration of FIG.

  The above embodiment uses a method that includes means (for example, an electrothermal converter) for generating thermal energy for ink ejection, and causes a change in the state of the ink by the thermal energy, among ink jet recording methods. High density and high definition of recording can be achieved.

  In addition, the ink jet recording apparatus according to the present invention may be used as an image output apparatus for information processing equipment such as a computer, a copying apparatus combined with a reader, or a facsimile apparatus having a transmission / reception function. It may be one taken.

1 is an external perspective view showing an outline of a configuration of an ink jet recording apparatus that is a representative embodiment of the present invention. 3 is a block diagram illustrating a configuration of a control circuit of the recording apparatus. FIG. 2 is an external perspective view showing a configuration of a head cartridge IJC in which an ink tank and a recording head are integrally formed. FIG. FIG. 3 is a circuit diagram illustrating a configuration of a temperature detection circuit formed on a head substrate of a recording head. FIG. 5 is a diagram showing a drive timing chart of the circuit shown in FIG. 4. FIG. 5 is a diagram showing a layout configuration of the head substrate shown in FIG. 4. It is a circuit diagram which shows the structure of the temperature detection circuit according to another Example. It is a figure which shows the structure of the temperature detection circuit of the conventional inkjet recording head.

Explanation of symbols

101 Recording element (heater)
102 Drive element (MOS transistor)
105 Control circuit 106 Temperature sensing element (diode)
107 Switching element (MOS transistor)
108, 109 Temperature detection output wiring 110 Detection signal control circuit 600 Controller 601 MPU
602 ROM
603 ASIC
604 RAM
605 System bus 605 A / D converter 610 Host device 611 Interface

Claims (12)

A head substrate comprising a plurality of heaters and a plurality of drive elements for driving the plurality of heaters,
A plurality of temperature sensing elements provided corresponding to each of the plurality of heaters;
An output circuit for outputting a signal from the temperature detection element in response to a drive signal for driving the plurality of heaters.   2. The head substrate according to claim 1, further comprising a detection signal control circuit that outputs a detection signal for designating an output timing of a signal from a temperature detection element corresponding to each of the heaters to the output circuit in accordance with the drive signal. . The output circuit is composed of MOS transistors,
The head substrate according to claim 1, wherein the plurality of temperature detection elements are configured by diodes connected in series to the MOS transistors. The plurality of temperature detection elements are composed of MOS transistors that also serve as the output circuit,
The head substrate according to claim 1, wherein the on-resistance of the MOS transistor has temperature dependence. Each of the plurality of driving elements is a MOS transistor,
A gate of the MOS transistor;
5. The head substrate according to claim 3, wherein the same drive signal as that for driving the plurality of heaters is commonly input to gates of the MOS transistors included in the plurality of temperature detection elements. . A voltage detection circuit for measuring a voltage change between one end of the MOS transistor and one end of the diode;
The head substrate according to claim 3, further comprising a constant current source that supplies a constant current to the voltage detection circuit. A voltage detection circuit for measuring a voltage change between both ends of the MOS transistor;
The head substrate according to claim 4, further comprising a constant current source that supplies a constant current to the voltage detection circuit.   6. The head substrate according to claim 5, wherein a MOS transistor of the driving element and a MOS transistor included in the temperature detection element are arranged adjacent to each other.   A recording head using the head substrate according to claim 1.   The recording head according to claim 9, wherein the recording head is an ink jet recording head that performs recording by discharging ink.   11. A head cartridge in which the recording head according to claim 10 and an ink tank containing ink to be supplied to the recording head are integrated.   A recording apparatus comprising the recording head according to claim 10 or the head cartridge according to claim 11.

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