JP2006007762A - Substrate for recording head, recording head, head cartridge, and recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a layout of a driving circuit which suppresses an increase of a head substrate area in an inkjet recording head by a driving system that applies a predetermined current to a heater. <P>SOLUTION: A plurality of recording elements whose number becomes greatly larger and a plurality of switching elements are arranged in a longitudinal direction of a head substrate. A plurality of terminals for inputting a driving signal and a control signal used for driving the plurality of recording elements are set at a position opposed to the arrangement of the plurality of recording elements at an end part of the substrate and in the longitudinal direction of the substrate. Constant current sources for flowing the predetermined current are disposed between these regions. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a recording head substrate, a recording head, a head cartridge, and a recording apparatus. In particular, the recording head is used for recording in accordance with, for example, an ink jet method and has a circuit for driving a recording element by applying a predetermined current. The present invention relates to a head substrate, a recording head, a head cartridge, and a recording apparatus.

  2. Description of the Related Art An ink jet recording head (hereinafter referred to as a recording head) that discharges ink by generating thermal energy by energizing a heater arranged in a nozzle is known.

  This recording head is a recording head that employs a system in which ink is bubbled in the vicinity of a heater using generated thermal energy and ink is ejected from the nozzle to perform recording.

  In order to perform recording at high speed, it is desirable to simultaneously drive as many heaters as possible mounted on the recording head to discharge ink at the same timing. However, the current value that can be flowed at one time is limited by the limitation of the power supply capability of the power source of the recording apparatus equipped with the recording head, the voltage drop due to the wiring resistance from the power source to the heater, and the like. For this reason, it is common to use a time-division drive method in which a plurality of heaters are driven in a time-division manner to discharge ink. For example, a plurality of heaters are divided into a plurality of groups, and time-sharing control is performed so that two or more heaters are not driven simultaneously in each group. There is no need to supply.

  FIG. 14 is a diagram showing a configuration example of a heater driving circuit mounted on a conventional ink jet recording head.

  The heater driving circuit shown in FIG. 14 is equipped with x heaters in m groups, and simultaneously drives one heater in each group, that is, m heaters, and performs this x times. It is configured to drive the cycle.

  As shown in FIG. 14, the MOS transistors 1102-11 to 1102-mx corresponding to the heaters 1101-11 to 1101-mx are each accommodated in the same number (x) as shown in FIG. It is divided into groups 1100-1 to 1100-m. That is, in the group 1100-1, the power supply wiring from the power supply pad (power supply terminal) 1103 is commonly connected to the heaters 11011-11 to 1101-1x, and each of the MOS transistors 1102-11 to 1102-1x is connected to the power supply. Between the pad 1103 and the ground (GND) 1104, the corresponding heaters 1101-11 to 1101-1x are connected in series.

  Each of the heaters 1101-11 to 1101-1x has the MOS transistors 1102-11 to 1102-1x when a control signal is applied from the control circuit 1105 to the gates of the corresponding MOS transistors 1102-11 to 1102-1x. When is turned on, a current flows from the power supply wiring through the corresponding heater and is heated.

  FIG. 15 is a timing chart showing the timing for energizing and driving the heaters in each group of the heater drive circuit shown in FIG. In this figure, the group 1100-1 in FIG. 14 is described as an example.

  In FIG. 15, control signals VG1 to VGx are timing signals for driving the first to xth heaters 1101-11 to 1101-1x belonging to the group 1100-1. That is, the control signals VG1 to VGx indicate the waveforms of signals input to the control terminals of the MOS transistors 1102-11 to 1102-1x in the group 1100-1, and the corresponding MOS transistors 1102-1i (i = 1, x) is turned on, and the corresponding MOS transistor is turned off when the level is low. The same applies to the other groups 1100-2 to 1100-m. In FIG. 15, Ih1 to Ihx indicate current values flowing through the heaters 1101-11 to 1101-1x, respectively.

  In this way, by sequentially energizing the heaters in each group in a time-sharing manner, it is possible to control the number of heaters that are energized and driven in each group to be always 1 or less. Need not be supplied to the heater.

  FIG. 16 is a diagram showing a layout of the power supply wirings connected to the groups 1100-1 to 1100-m from the power supply pad 1103 shown in FIG. In other words, FIG. 16 can be said to be a diagram showing a part of the layout of the substrate (head substrate) on which the heater driving circuit shown in FIG. 14 is formed. FIG. 16 shows a layout of a power supply wiring portion when a heater (not shown) is arranged on the upper side of the drawing.

  As shown in FIG. 16, power supply wirings 1301-1 to 1301-m are individually connected to the groups 1100-1 to 1100-m from the power supply pad 1103, and the power supply wiring 1302 is connected to the ground (GND) pad 1104. -1 to 1302-m are connected. As described above, in a time division drive in which one recording element in each group is sequentially driven in a recording head including m × x heaters (recording elements), m power supply wirings and ground wirings are provided. Necessary.

  As described above, by setting the maximum number of heaters driven simultaneously in each group to 1 or less, the current value flowing through the wiring divided for each group can always be equal to or less than the current flowing to one heater. As a result, even when a plurality of heaters are driven simultaneously, the voltage drop amount in the wiring in the heater substrate can be constant, and at the same time, even when a plurality of heaters belonging to different groups are driven simultaneously, The amount of energy input to each heater can be made substantially constant.

  In recent years, recording apparatuses are required to have higher speed and higher definition, so that the mounted recording head is also mounted with more nozzles at higher density. When the heater of the recording head is driven, it is required to drive as many heaters as possible simultaneously at high speed from the viewpoint of recording speed.

  In addition, a recording head substrate (hereinafter referred to as a head substrate) on which a heater and its drive circuit are mounted has a large number of heaters and their drive circuits formed on the same semiconductor substrate. For this reason, since it is necessary to reduce the cost by increasing the number of heater substrates that can be taken from one semiconductor wafer in the manufacturing process, it is also required to reduce the size of the head substrate.

  However, as described above, when the number of simultaneously driven heaters is increased, the number of wires corresponding to the number of simultaneously driven heaters is required in the head substrate. For this reason, when the number of wirings is increased, when the head substrate area is limited, the wiring area per wiring is reduced, so that the wiring resistance increases. At the same time, each wiring width is narrowed, so that the resistance variation between the wirings in the head substrate also increases. Such a problem also occurs when the head substrate is reduced in size, and further increases in wiring resistance and variations in resistance. As described above, since the heater and the power supply wiring are connected in series with the power supply in the head substrate, the variation rate of the voltage applied to each heater increases due to an increase in the wiring resistance and the resistance variation. Will increase.

  If the input energy to the heater is too small, the ink ejection becomes unstable, and if it is excessive, the durability of the heater is lowered. That is, when the voltage applied to the heater varies greatly, the durability of the heater is lowered or the ink ejection becomes unstable. For this reason, in order to perform high-quality recording, it is desirable that the energy input to the heater is constant, and it is desirable that the energy input is stable from the viewpoint of durability.

In the time-division drive in which the number of simultaneous drives is set to one or less for each group described above, it is possible to suppress the voltage drop inside the head substrate, but the wiring outside the head substrate is connected to a plurality of groups. Since it is common to the heaters, the amount of voltage drop in the common wiring varies depending on the number of heaters driven simultaneously. In order to make the input energy to each heater constant with respect to such fluctuations in voltage drop, conventionally, the input energy to each heater is adjusted by the voltage application time.
However, when the number of simultaneously driven heaters increases, the amount of voltage drop increases due to the amount of current flowing through the common wiring, and the voltage applied to the heaters decreases. As a result, in order to compensate for this, there is a problem in that it is difficult to drive the heater at high speed because the voltage application time during driving of the heater must be increased.

  As a method for solving such a problem caused by fluctuations in the input energy to the heater, for example, Patent Document 1 proposes a method of driving a recording element with a constant current.

  FIG. 17 is a diagram illustrating a heater driving circuit disclosed in Patent Document 1. In FIG.

In this configuration, the recording elements (R1 to Rn) are driven with a constant current by using the constant current sources (Tr14 to (n + 13)) and switching elements (Q1 to Qn) provided for the respective recording elements (R1 to Rn). is doing.
JP 2001-191531 A

  However, in the case of the constant current driving disclosed in Patent Document 1, the same number of transistors as the recording elements are required in addition to the switching elements (Q1 to Qn), so that the area of the heater substrate is remarkably increased as compared with the conventional driving method. There is a problem that the cost of the heater substrate is increased.

  In addition, in order to stabilize the energy input to the heater, the output current is required to be constant among a plurality of constant current sources. However, as the number of constant current sources increases, the constant current source increases. There also arises a problem that variation in output current increases. In particular, it is difficult to reduce the amount of variation in output current among a plurality of constant current sources in a head substrate having a significantly increased number of heaters due to high-speed recording and high definition of the recording apparatus.

  The present invention has been made in view of the above-described conventional example, and while adopting a constant current driving method of supplying a constant current to each recording element to drive the recording element, it is possible to achieve a reduction in substrate size and at a high speed. To provide a recording head substrate capable of driving a recording element, a recording head using the recording head substrate, a head cartridge incorporating the recording head, and a recording apparatus using the recording head. It is an object.

  For this miniaturization, a drive circuit that overcomes the above-described problems of the prior art is optimally arranged on the head substrate.

  In order to achieve the above object, the recording head substrate of the present invention is configured as follows.

  That is, a recording head adopting a driving method for driving the plurality of recording elements by causing a constant current to flow to the plurality of recording elements provided on the substrate via the plurality of switching elements corresponding to the plurality of recording elements. A plurality of recording elements and a plurality of switching elements arranged in a longitudinal direction of the substrate, at an end of the substrate, and on a side different from an arrangement position of the plurality of recording elements A plurality of terminals for inputting drive signals and control signals used for driving the plurality of recording elements in the longitudinal direction of the substrate at the substrate end position, and a constant current source for flowing the constant current, It arrange | positions in the position near the area | region where these terminals are arrange | positioned rather than the area | region where these switching elements are arranged.

  Furthermore, it is preferable that a control circuit for controlling driving of the plurality of switching elements is provided, and the constant current source is disposed at a position closer to a region where the plurality of terminals are disposed than the control circuit.

  In such a configuration, when a plurality of the constant current sources are provided, the plurality of constant current sources may be arranged at equal intervals in the longitudinal direction of the substrate.

  Alternatively, when a plurality of the constant current sources are provided, the plurality of constant current sources are arranged in the longitudinal direction of the substrate, and the arrangement is concentrated on the central portion of the substrate. good.

  As another aspect, there is provided a driving method for driving the plurality of recording elements by causing a constant current to flow to the plurality of recording elements provided on the substrate via the plurality of switching elements corresponding to the plurality of recording elements. The recording head substrate employed, wherein the plurality of recording elements and the plurality of switching elements are arranged in a longitudinal direction of the substrate, are at an end of the substrate, and are arranged at the positions of the plurality of recording elements. For arranging the plurality of terminals for inputting drive signals and control signals used for driving the plurality of recording elements in the longitudinal direction of the substrate at the end position of the substrate on the different side, and for passing the constant current A plurality of constant current sources may be provided in a region between each of the plurality of terminals, and a recording head substrate may be provided.

  With the above configuration, a control circuit for controlling on / off of the plurality of switching elements based on the drive signal and the control signal may be further arranged in the longitudinal direction of the substrate.

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

  The recording head is preferably an ink jet recording head that performs recording by discharging ink.

  According to still another aspect of the invention, there is provided a head cartridge that integrally includes the ink jet recording head and an ink tank that holds ink to be supplied to the recording head.

  According to still another aspect of the invention, there is provided a recording apparatus that performs recording by ejecting ink onto a recording medium using the ink jet recording head or the head cartridge having the above configuration.

  Therefore, according to the present invention, not only can the substrate area be used effectively, but also the wiring length between the recording element, the switching element, the constant current source, and the pad can be shortened on the substrate. There is an effect that it is possible to provide a head substrate using a constant current driving method capable of high-speed and stable recording without greatly increasing.

  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.

  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.

  The “constant current” and “constant current source” in the present invention are a predetermined constant current applied to the recording element regardless of fluctuations in the number of simultaneously driven recording elements, and a current source that supplies this current to the recording element. It means that. The current value itself to be constant includes the case where the current value is changed to a predetermined current value.

<Description of Inkjet Recording Apparatus (FIG. 1)>
FIG. 1 is a schematic view of an ink jet recording apparatus which is a typical embodiment of the present invention. In FIG. 1, the lead screw 5005 rotates via driving force transmission gears 5009 to 5011 in conjunction with forward and reverse rotation of the carriage motor 5013. The carriage HC has a pin (not shown) that engages with the spiral groove 5005 of the lead screw 5004, and is supported by the guide rail 5003 as the lead screw 5004 rotates so as to reciprocate in the directions of arrows a and b. Is done. An ink jet cartridge IJC is mounted on the carriage HC. The ink jet cartridge IJC includes an ink jet recording head IJH (hereinafter referred to as a recording head) and an ink tank IT for storing recording ink.

  The ink jet cartridge IJC has a configuration in which the recording head IJH and the ink tank IT are integrated.

  Reference numeral 5002 denotes a paper pressing plate that presses the paper against the platen 5000 in the moving direction of the carriage. The platen 5000 is rotated by a conveyance motor (not shown) to convey the recording paper P. Reference numerals 5007 and 5008 denote home position detecting means for confirming the presence of the lever 5006 of the carriage in this region and switching the rotation direction of the motor 5013. Reference numeral 5016 denotes a member that supports a cap member 5022 that caps the front surface of the recording head. Reference numeral 5015 denotes suction means for sucking the inside of the cap, and performs suction recovery of the recording head through the opening 5023 in the cap. Reference numeral 5017 denotes a cleaning blade, and reference numeral 5019 denotes a member that enables the blade to move in the front-rear direction, and these are supported by a main body support plate 5018. Needless to say, the blade is not in this form, and a known cleaning blade can be applied to this example. Reference numeral 5012 denotes a lever for starting suction for suction recovery, which moves in accordance with the movement of the cam 5020 engaged with the carriage, and the driving force from the driving motor is controlled by a known transmission means such as clutch switching. Is done.

  These capping, cleaning, and suction recovery are configured so that desired processing can be performed at their corresponding positions by the action of the lead screw 5004 when the carriage comes to the home position side region. Any of these can be applied to this example as long as the above operation is performed.

  FIG. 2 is an external perspective view showing a detailed configuration of the ink jet cartridge IJC.

  As shown in FIG. 2, the ink jet cartridge IJC is composed of a cartridge IJCK that discharges black ink and a cartridge IJCC that discharges three color inks of cyan (C), magenta (M), and yellow (Y). These two cartridges are separable from each other and can be detached from the carriage HC independently of each other.

  The cartridge IJCK includes an ink tank ITK that stores black ink and a recording head IJHK that discharges and records black ink. These cartridges have an integrated configuration. Similarly, the cartridge IJCC includes an ink tank ITC that stores three color inks of cyan (C), magenta (M), and yellow (Y), and a recording head IJHC that discharges and records these color inks. However, these are integrated. In this embodiment, the ink tank is filled with ink.

  In addition, the cartridges IJCK and IJCC can be used not only as an integral type, but also as a configuration in which the ink tank and the recording head are separated.

  The recording head IJH is used when collectively referring to the recording head IJHK and the recording head IJHC.

  Further, as apparent from FIG. 2, the nozzle row for ejecting black ink, the nozzle row for ejecting cyan ink, the nozzle row for ejecting magenta ink, and the nozzle row for ejecting yellow ink are arranged side by side in the carriage movement direction. The nozzle arrangement direction intersects the carriage movement direction.

  FIG. 3 is a perspective view showing a part of a three-dimensional structure of a recording head that ejects ink.

  FIG. 3 illustrates two nozzles that are supplied with cyan (C) ink and eject ink droplets. However, the number of nozzles is usually much larger than this, and the structure is different. The same applies to color inks.

  The recording head IJHC has an ink channel 2C for supplying cyan (C) ink, an ink channel (not shown) for supplying magenta (M) ink, and an ink channel (not shown) for supplying yellow (Y) ink. A supply path (not shown) for supplying each ink to each ink channel is provided from the ink tank ITC.

  In particular, FIG. 3 reveals the flow of cyan (C) ink supplied from the ink tank ITC.

  As shown in FIG. 3, an ink flow path 301 </ b> C is provided corresponding to the electrothermal converter (heater) 401, and the C ink passes through the ink flow path and is provided on the substrate. (Heater) 401 is led. When the electrothermal converter (heater) 401 is energized through a circuit to be described later, heat is applied to the ink on the electrothermal converter (heater) 401, and the ink boils, resulting in the occurrence. The ink droplet 900C is ejected from the ejection port 302C by bubbles.

  In the illustrated configuration, the ink ejection port 302C, the ink channel 2C, and the ink flow path 301C are arranged in a straight line, but the ejection port 302 is provided on the side facing the electrothermal transducer (heater) 401. A so-called side shooter type configuration may be used.

  In FIG. 3, reference numeral 1 denotes an electrothermal transducer to be described in detail later, various circuits for driving the memory, memory, various pads serving as electrical contacts with the carriage HC, and recording on which various signal lines are formed. A head substrate (hereinafter referred to as a head substrate).

  One electrothermal transducer (heater) and the MOS-FET that drives the electrothermal converter are collectively referred to as a recording element, and a plurality of recording elements are collectively referred to as a recording element unit.

  Although FIG. 3 shows the three-dimensional structure of the recording head IJHC that discharges one color ink (cyan ink) among a plurality of color inks, the recording head that discharges inks of other colors has the same structure. ing.

  Next, a control configuration for executing the recording control of the recording apparatus described above will be described.

  FIG. 4 is a block diagram showing the configuration of the control circuit of the recording apparatus.

  In FIG. 4, 1700 is an interface for inputting a recording signal, 1701 is an MPU, 1702 is a ROM for storing a control program executed by the MPU 1701, and 1703 is various data (such as the recording signal and recording data supplied to the recording head). This is a DRAM to be stored. Reference numeral 1704 denotes a gate array (GA) that controls supply of print data to the print head IJH, and also controls data transfer among the interface 1700, MPU 1701, and RAM 1703.

  Further, reference numeral 1709 denotes a conveyance motor (not shown in FIG. 1) for conveying the recording paper P, 1706 denotes a motor driver for driving the conveyance motor 1709, 1707 denotes a motor driver for driving the carriage motor 1710, and 1705 denotes recording. It is a head driver for driving the head IJH.

  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. Then, the motor drivers 1706 and 1707 are driven, and the recording head IJH is driven in accordance with the recording data sent to the carriage HC, and image recording on the recording paper P is performed.

  In this embodiment, the recording head configured as shown in FIG. 2 is used, and control is performed so that the recording by the recording head IJHK and the recording by the recording head IJHC do not overlap in each scanning of the carriage. In the case of color recording, the recording head IJHK and the recording head IJHC are driven alternately for each scan. For example, when the carriage performs reciprocal scanning, control is performed so that the recording head IJHK is driven in the forward scanning and the recording head IJHC is driven in the backward scanning. The drive control of the print head is not limited to such control, and the print operation is performed only by the forward scan, and the print head IJHK and the print head IJHC are driven by the two forward scans without carrying the recording paper P. Other controls may be performed.

  Next, the configuration and operation of the head substrate mounted on the recording head IJH will be described.

  FIG. 5 is a diagram showing a configuration example of a head substrate forming a heater driving circuit built in the recording head IJH.

  In FIG. 5, the same components as those already described in FIG. 14 of the conventional example are denoted by the same reference numerals, and the description thereof is omitted. In the configuration shown in FIG. 5, as in the conventional example, (m × x) heaters and switching elements (MOS transistors) are divided into m groups each consisting of x heaters and switching elements. At the same time, an example is shown in which a time-division drive method in which one heater is selectively driven in each group is shown.

  In FIG. 5, 103-1 to 103-m are constant current source groups, and 105 is a reference current circuit.

  As shown in FIG. 5, the heater driving circuit is connected to constant current sources 103-1 to 103-m for supplying current to the heaters for each group.

  For example, in the group 1100-1, the source side terminals of the MOS transistors 1102-11 to 1102-1 connected in series to each of the heaters 1101-11 to 1101-1x are commonly connected, and one end of the heater of each group is also commonly connected. The constant current source 103-1 is connected to the group. Further, the power supply wiring 108 is connected to a common connection end of each of the heaters 1101-11 to 1101-1 x.

  MOS transistors 1102-11 to 1102-1x, which are driving switches for the heaters 1101-11 to 1101-1x, are connected in series between the power supply wiring 108 and the ground (GND). Further, the high withstand voltage MOS transistor 103-1, which is one of constant current source groups for supplying a predetermined current to the heaters 1101-11-11101-1x, is connected to the MOS transistors 1102-11-1110-1x and the ground (GND). Are connected in series as a common switch. In this embodiment, the MOS transistor (constant current source) 103 is operated in its saturation region so that a predetermined current can flow.

  The configurations of the other groups 1100-2 to 1100-m are the same as the group 1100-1.

  Accordingly, when viewing the heater driving circuit as a whole, the heaters 11011-11 to 1101-mx, the MOS transistors 1102-11 to 1102-mx functioning as switches, and the constant current source groups 103-1 to 103- from the power supply wiring 108 side. m and ground wiring are connected in series in this order. Each of the constant current source groups 103-1 to 103-m outputs a constant current to the common connection end of the corresponding block. The magnitude of the output current value is adjusted by a control signal from the reference current circuit 105.

  Next, the operation of the heater drive circuit having the above circuit configuration will be described.

  Since this operation is common to m groups, only one group composed of x heaters will be described here.

  FIG. 6 is a circuit diagram showing the configuration of one group of the heater drive circuit shown in FIG.

  In FIG. 6, the same components as those already described with reference to FIGS. 14 and 5 of the conventional example are denoted by the same reference numerals, and description thereof is omitted.

  In FIG. 6, VG1, VG2,..., VG (x-1), VGx are switching MOS transistors 1102-11, 1102-12, ... 1102-1 (x-1), 1102- , Ih1, Ih2,..., Ih (x-1), Ihx are heaters 1101-11, 1101-12,. 1 (x-1), 1101-1x, and VC represents a control signal from the reference current circuit 105.

  For the sake of simplicity, the switching MOS transistors 1102-11 to 1102-1x are considered to operate ideally as a two-terminal switch of a drain and a source, and the signal level of VGi (i = 1, x) is “ In the following description, it is assumed that the switch is turned on (the drain-source is short-circuited) if it is H and turned off (the drain-source is opened) if it is "L". The constant current source 103-1 outputs a constant current set by the control signal VC between the terminals (from the top to the bottom in the figure) when a voltage between the terminals is applied. .

  FIG. 7 is a diagram showing the waveform of the control signal (VGi) and the current (Ihi) flowing through the heater according to the control signal.

  For example, regarding the control signal VG1, it is “L” in the period up to time t1, the output of the constant current source 103-1 and the heater 1101-11 are cut off, and no current flows through the heater. However, during the period from time t1 to t2, it becomes “H”, the source-drain of the MOS transistor 1102-11 which is a constant current source is energized, and the output current from the constant current source 103-1 flows to the heater. . Thereafter, it becomes “L” again from time t2, and the current to the heater is cut off.

  The same applies to the control signals VG2,.

  The current application time to the heater is controlled by the control signal VGi, and the magnitude of the heater input current Ihi is controlled by the control signal VC to the constant current source 103-1.

  As described above, when a current flows through the heater 1101-11 during the period from the time t1 to the time t2, the ink on the upper surface of the heater is heated and foamed. As a result, the ink is ejected from the corresponding nozzle and the ink dot is recorded. Is done.

  In the same manner, the current sequentially flows to the heaters 11011-11 to 1101-1x in accordance with the signals shown in the timing chart shown in FIG. 7, and as a result, the recording of the ink dots by the ejection of the heated ink and the heater 1101- The current supply to 11 to 1101-1x is stopped.

  With the above configuration, the output current value of the constant current source 103-1 is set by the reference current circuit 105, and the set output current is set to the heaters 1101-11 through the MOS transistors 1102-11 to 1102-1 x for a desired time. 1101-1x.

  In actual operation, a resistance exists between the source and the drain when the MOS transistors 1102-11 to 1102-1x are on. By setting a sufficiently high power supply voltage with respect to the voltage drop in the resistance. The output current of the constant current source flows to the heater as it is, and an operation substantially the same as when no on-resistance exists is realized.

  Hereinafter, the circuit layout configuration of the head substrate according to the present invention in which the heater driving circuit for performing the above circuit configuration and operation will be described.

  FIG. 8 is a diagram showing a layout configuration of the head substrate according to the first embodiment of the present invention.

  FIG. 8 is an example of a layout configuration for showing an actual arrangement on the head substrate for each element such as a heater, a transistor, a control circuit, and a constant current source in the heater driving circuit (equivalent circuit) shown in FIG. . Therefore, also in FIG. 8, the same reference numerals are assigned to the arrangement regions corresponding to the components referred to in FIG. The head substrate according to the present invention is a rectangular substrate, and the substrate has a short side and a long side. A heater, a switching transistor, and the like are arranged in a direction (longitudinal direction) along the long side of the head substrate.

  For example, in the group 1100-1, a heater group having heaters 1101-111 to 1101-1x and a transistor group having switching MOS transistors 1102-11 to 1102-1x are formed. Similarly, in the group 1100-m, a heater group of heaters 1101-m1-1101-mx and a transistor group of MOS transistors 1102-m1-110-mx are formed. Further, a constant current source group 103 configured by m constant current sources 103-1 to 103-m that supply a predetermined current for each group is arranged corresponding to each of the m groups.

  The control circuit 1105 is also divided into m groups 1105-1 to 1105-m corresponding to the heaters and MOS transistors belonging to each group.

  Furthermore, the arrangement intervals of the constant current sources 103-1 to 103-m for supplying a predetermined current to the heaters of each group are set to m groups 1100-1 to 1100- composed of x heaters and MOS transistors. It is substantially equal to the arrangement interval of the array of m, and is arranged corresponding to each group.

  In the head substrate according to this embodiment, an input / output pad group 1501 including various contacts such as VH contacts and pads 106 and 107 serving as electrical contacts with the carriage is provided in a direction along the long side of the head substrate. It is arranged.

  FIG. 9 is a diagram showing a layout of the power supply wiring portion of the head substrate shown in FIG.

  Note that a partial cross-sectional view of the ink jet recording head using the head substrate shown in FIGS. 8 and 9 is configured as shown in FIG.

  In FIG. 9, all the elements shown in FIG. 8 are drawn with broken lines, and since this substrate has a multilayer structure, it is located in the lower layer of the illustrated power supply wiring.

  As shown in FIG. 9, the power supply wiring 108 is connected to the pad 106 on the power supply side, and connected to the heater group 1101 of each of the groups 1100-1 to 1100-m via the VH contact. The output side terminal of the constant current source group 103 and the source side terminal of the MOS transistor group 1102 are connected to each other by the wirings 50-1 to 50-m, respectively. A ground (GND) side terminal of the constant current source group 103 is connected to the GND pad 107 via a wiring 109 extending in the longitudinal direction of the head substrate.

  As can be seen from FIGS. 8 and 9, in the head substrate according to this embodiment, the heater group 1101 and the input / output pad group 1501 are arranged at two locations near the end on the long side of the head substrate. , Arranged substantially parallel to each other. The heater group 1101, the MOS transistor group 1102, and the control circuit 1105 are arranged in this order from the end of the head substrate, and the constant current source 103 is arranged between the control circuit 1105 and the input / output pad group 1501.

  Now, in order to heat and foam the ink by the heater and eject it from the nozzle, it is necessary to input a current of about several tens mA to 100 mA per heater. Therefore, for efficient power consumption, it is necessary to minimize power loss and heat generation in the wiring connected in series to the heater other than the heater due to this current.

  According to this embodiment, since the constant current source is arranged between the switching element (MOS transistor) and the pad in the layout configuration of the head substrate in which the heater and the pad are arranged in parallel, the heater, the switching element, The wiring connecting each element of the constant current source and the pad and the pad can be minimized, and the power loss due to the wiring can be minimized.

  Further, since the constant current source of each group is arranged at the same group position together with the heater, the switching MOS transistor, and the control circuit, the length of the wiring between these elements is substantially reduced between the groups. Can be equal. Thereby, the dispersion | variation in the characteristic between each group can be suppressed.

  Furthermore, as can be understood from FIGS. 5 and 8 to 9, the constant current source is a circuit for passing a current through the MOS transistor group, but is arranged at a position closer to the input / output pad than the control circuit. Yes. As a result, the length of the wiring from the pad shared by the plurality of groups to the constant current source is shortened, thereby reducing the cause of operation variations during circuit driving.

  FIG. 10 is a diagram showing a layout configuration of the head substrate according to the second embodiment of the present invention.

  FIG. 10 is an example of a layout configuration for realizing the heater driving circuit shown in FIG. FIG. 11 is a diagram showing the layout of the power supply wiring of the head substrate shown in FIG.

  10 to 11, the same constituent elements as those mentioned in FIGS. 5, 8, and 9 are denoted by the same reference numerals.

  As can be seen by comparing FIGS. 8 to 9 described in the first embodiment and FIGS. 10 to 11 of this embodiment, in this embodiment, the arrangement of the constant current source group 103 is concentrated on the central portion of the substrate. The arrangement interval is shorter than the arrangement interval of the heater group 1101.

  Therefore, according to this embodiment, the distance between the constant current sources is shortened, so that the relative current error of the output current of each constant current source due to variations in the semiconductor manufacturing process can be reduced. Further, the wiring length from the GND pad 107 to the source of the MOS transistor constituting the constant current source can be further shortened, and the absolute value of the variation of the wiring resistance is reduced, and similarly the relative error of the output current is reduced. can do.

  FIG. 12 is a diagram showing a layout configuration of the head substrate according to the third embodiment of the present invention.

  FIG. 13 shows an example of a layout configuration for realizing the heater driving circuit shown in FIG. FIG. 13 is a diagram showing the layout of the power supply wiring of the head substrate shown in FIG.

  12 to 13, the same reference numerals are given to the same components as those mentioned in FIGS. 5, 8, and 9.

  As can be seen by comparing FIGS. 8 to 9 described in the first embodiment and FIGS. 12 to 13 of this embodiment, in this embodiment, each of the constant current sources 103-1 to 103-1 constituting the constant current source group 103 is described. 103-m is arranged between the input / output pad groups 106, 107 and the like.

  In the ink jet recording head considered in the present invention, the recording speed is increased by arranging as many heaters as possible and increasing the number of simultaneously driven heaters. For this reason, the heater substrate is generally elongated in the heater arrangement direction. Therefore, in a head substrate having an input / output pad arranged in the heater arrangement direction, the arrangement interval of the input / output pads is sufficiently longer than the pad size, and a sufficient space is created between the pads.

  Therefore, in this embodiment, by arranging the constant current source in this space, the space on the substrate is effectively used, and as a result, the substrate size is not increased. Furthermore, according to this embodiment, the direction perpendicular to the heater array (the short direction of the head substrate) can be reduced, which contributes to reducing the cost of the head substrate.

1 is an external perspective view showing an outline of a configuration of a carriage peripheral portion of an ink jet recording apparatus that is a representative embodiment of the present invention. It is an external appearance perspective view which shows the detailed structure of the inkjet cartridge IJC. FIG. 3 is a perspective view showing a three-dimensional structure of a part of a recording head IJH that ejects ink. FIG. 2 is a block diagram illustrating a control configuration of the recording apparatus illustrated in FIG. 1. FIG. 3 is a diagram illustrating a configuration example of a head substrate that forms a heater driving circuit mounted on a recording head IJH. FIG. 6 is a circuit diagram showing a configuration of one block of the heater drive circuit shown in FIG. 5. It is a figure which shows the waveform of the electric current (Ihi) which flows into a heater according to a control signal (VGi) and the control signal. It is a figure which shows the layout structure of the head substrate according to Example 1 of this invention. FIG. 9 is a diagram showing a layout of power supply wiring of the head substrate shown in FIG. 8. It is a figure which shows the layout structure of the head substrate according to Example 2 of this invention. It is a figure which shows the layout of the power supply wiring of the head substrate shown in FIG. It is a figure which shows the layout structure of the head substrate according to Example 3 of this invention. It is a figure which shows the layout of the power supply wiring of the head substrate shown in FIG. It is a figure which shows the structural example of the heater drive circuit mounted in the conventional inkjet recording head. It is a timing chart which shows the timing which energizes and drives the heater of each block of the heater drive circuit shown in FIG. It is the figure which showed the layout of the power supply wiring connected to the blocks 1100-1 to 1100-m from the power supply pad 1103 shown in FIG. It is a figure which shows the heater drive circuit according to a prior art.

Explanation of symbols

103 constant current source group 103-1 to 103-m constant current source 105 reference current circuit 1101-11 to 1101mx heater 1102-11 to 1102mx MOS transistor 1105 control circuit IJH print head

Claims (10)

Printhead substrate employing a driving method for driving the plurality of recording elements by passing a constant current through a plurality of switching elements corresponding to the plurality of recording elements to the plurality of recording elements provided on the substrate Because
Arranging the plurality of recording elements and the plurality of switching elements in a longitudinal direction of the substrate;
Drive signals and control signals used to drive the plurality of recording elements in the longitudinal direction of the substrate at the substrate end position which is an end portion of the substrate and is different from the arrangement position of the plurality of recording elements. Arrange multiple terminals to input
A recording head substrate, wherein the constant current source for causing the constant current to flow is arranged at a position closer to an area where the plurality of terminals are arranged than an area where the plurality of switching elements are arranged. A control circuit for controlling driving of the plurality of switching elements;
The recording head substrate according to claim 1, wherein the constant current source is disposed at a position closer to an area where the plurality of terminals are disposed than the control circuit. A plurality of the constant current sources are provided,
2. The recording head substrate according to claim 1, wherein the plurality of constant current sources are arranged at equal intervals in the longitudinal direction of the substrate. A plurality of the constant current sources are provided,
The plurality of constant current sources are arranged in a longitudinal direction of the substrate;
2. The recording head substrate according to claim 1, wherein the arrangement is concentrated at a central portion of the substrate. Printhead substrate employing a driving method for driving the plurality of recording elements by passing a constant current through a plurality of switching elements corresponding to the plurality of recording elements to the plurality of recording elements provided on the substrate Because
Arranging the plurality of recording elements and the plurality of switching elements in a longitudinal direction of the substrate;
Drive signals and controls used to drive the plurality of recording elements in the longitudinal direction of the substrate at the end position of the substrate that is an end portion of the substrate and is different from the arrangement position of the plurality of recording elements. Arrange multiple terminals to input signals,
A recording head substrate, wherein a plurality of constant current sources for allowing the constant current to flow are arranged in a region between each of the plurality of terminals.   6. The recording head substrate according to claim 5, wherein a control circuit for controlling on / off of the plurality of switching elements based on the drive signal and the control signal is arranged in a longitudinal direction of the substrate.   A recording head using the recording head substrate according to claim 1.   The recording head according to claim 7, wherein the recording head is an ink jet recording head that performs recording by discharging ink.   9. A head cartridge comprising an ink tank for holding ink to be supplied to the ink jet recording head according to claim 8.   A recording apparatus that performs recording by discharging ink onto a recording medium using the ink jet recording head according to claim 8 or the head cartridge according to claim 9.

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