JP2006007761A - 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 constant current driving system. <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. Terminals for inputting a driving signal and a control signal used for driving the plurality of recording elements are set at an end part of the substrate and in a direction opposite to the longitudinal direction of the substrate. On the other hand, current sources for flowing a predetermined current are disposed at a region 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. 17 is a diagram showing a configuration example of a heater driving circuit mounted on a conventional ink jet recording head.

  The heater drive circuit shown in FIG. 17 is equipped with x heaters in m groups, and simultaneously drives one heater in each group, that is, m heaters simultaneously. It is configured to drive the cycle.

  As shown in FIG. 17, the MOS transistors 1102-11 to 1102-mx corresponding to the heaters 1101-11 to 1101-mx, respectively, are 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. 18 is a timing chart showing timing for energizing and driving the heaters of each group of the heater driving circuit shown in FIG. In this figure, the group 1100-1 in FIG. 17 is described as an example.

  In FIG. 18, 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. 18, 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. 19 is a diagram showing a layout of 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. 19 can be said to be a diagram showing a part of the layout of the substrate (head substrate) on which the heater drive circuit shown in FIG. 17 is formed. FIG. 19 shows a layout of a power supply wiring portion in the case where a heater (not shown) is arranged on the upper side of the drawing sheet.

  As shown in FIG. 19, 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. 20 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 each recording element (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.

  In order to reduce the size, a drive circuit that overcomes the above-described problems of the conventional technology 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. The substrate is a substrate having a long side and a short side, the plurality of recording elements and the plurality of switching elements are arranged in a longitudinal direction of the substrate, and the short side of the substrate is arranged. A terminal for inputting a drive signal and a control signal used for driving the plurality of recording elements is arranged at an end, and the constant current source for flowing the constant current is a first element in which the terminal is arranged. It is arranged in a region between the region and the second region in which the plurality of recording elements and the plurality of switching elements are arranged.

Furthermore, it is desirable that a control circuit for controlling on / off of the plurality of switching elements is arranged in the longitudinal direction of the substrate based on the drive signal and the control signal.
It is desirable that a supply port for supplying ink is provided in the longitudinal direction of the substrate.

The plurality of recording elements are grouped into a plurality of groups, the recording elements belonging to the same group are not simultaneously driven, the plurality of recording elements belonging to different groups are simultaneously driven, and a plurality of the current sources are provided. Preferably, the plurality of current sources are provided corresponding to each of the plurality of groups, and the plurality of current sources are collectively arranged in a region between the first region and the second region.
The constant current source is preferably composed of a MOS transistor that operates in a saturation region.

  The distances from the terminals to the plurality of constant current sources corresponding to the plurality of groups are preferably substantially equal.

  Furthermore, a reference current circuit that generates a reference current used by the current source to generate a constant current, a voltage-current conversion circuit that generates the reference current based on a reference voltage, and a reference voltage that generates the reference voltage And the reference current circuit, the voltage-current conversion circuit, and the reference voltage circuit are preferably arranged between the first region and the second region.

  In addition, a group of circuit elements obtained by arranging the current source between the first region and the second region is at least one of vertically symmetric and laterally symmetric on the substrate. As shown, a plurality may be arranged.

  The plurality of switching elements are preferably MOS transistors.

  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 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, a plurality of recording elements and a plurality of switching elements whose number is very large are arranged in the longitudinal direction of the substrate, and a plurality of recording elements are arranged at the edge of the substrate and in the lateral direction of the substrate. While pads for inputting drive signals and control signals used for driving are arranged, and constant current sources for passing a constant current are arranged between these regions, if the substrate area can be used effectively In addition, since the wiring length from the signal input pad to the constant current source can be shortened on the substrate, a constant current driving method capable of high-speed and stable recording without greatly increasing the head substrate size was used. There is an effect that a head substrate can be provided.

  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 individual elements are 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 the 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 three-dimensional structure of a recording head IJHC that discharges three color inks.

  From FIG. 3, the flow of ink supplied from the ink tank ITK becomes clear. The recording head IJHC has an ink channel 2C that supplies cyan (C) ink, an ink channel 2M that supplies magenta (M) ink, and an ink channel 2Y that supplies yellow (Y) ink. The ink channels are provided with supply paths (not shown) for supplying respective inks from the back side of the substrate.

  Ink channels 301C, 301M, and 301Y are provided corresponding to the electrothermal transducers (heaters) 401, and C ink, M ink, and Y ink are provided on the substrate through these ink channels, respectively. It is led to an electrothermal converter (heater) 401. 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. Ink droplets 900C, 900M, and 900Y are ejected from the ejection ports 302C, 302M, and 302Y by bubbles.

  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 color ink, the recording head IJHK that discharges black ink also has the same structure. However, the structure is one third of the configuration shown in FIG. That is, there is one ink channel, and if the number of recording elements to be arranged is the same, the size of the head substrate is about one third.

  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. 17 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 group. 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. 17 and 5 of the conventional example are denoted by the same reference numerals, and the 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 the time t1 to the time t2, it becomes “H”, the current between the source and drain of the MOS transistor 1102-11 as the 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. In the group 1100-2, a heater group having heaters 1101-21 to 1101-2x and a transistor group having switching MOS transistors 1102-21 to 1102-2x are formed. Similarly, in the group 1100-m, a heater group having heaters 1101-m1-1101-mx and a transistor group having MOS transistors 1102-m1-110-mx are formed. Further, a constant current source group 103 including m constant current sources 103-1 to 103-m that supply current for each group is formed corresponding to each of the m groups.

  In the direction along the short side of the head substrate (short side), various contacts such as VH contacts and input / output pad groups 1501 serving as electrical contacts with the carriage are formed.

  FIG. 9 is a partial sectional view of an ink jet recording head using the head substrate shown in FIG.

  As shown in FIG. 9, an ejection port 302 is provided at a position facing the heater 1101-2X provided on the head substrate 1, and the ink supply path 20 formed at the end of the head substrate 1 is provided. The ink supplied to the heater position is heated and discharged from the discharge port 302.

  FIG. 10 is a diagram showing a layout of the power supply wiring portion of the head substrate shown in FIG.

  As can be seen from FIG. 10, the power supply wirings 1601-1 to 1601-m are connected to the power supply pad 1103 and connected to the heaters 1101-11 to 1101-mx of the groups 1100-1 to 1100-m via VH contacts. On the other hand, the power supply wirings 1602-1 to 1602-m are connected to the output side terminals of the constant current source group 103 and the source side terminals of the MOS transistors 1102-11 to 1102-mx for each group. The ground (GND) side terminal of the constant current source group 103 is connected to the GND pad 1104 via the power supply wiring 1603 in common.

  As can be seen from the layout configuration shown in FIG. 8, the constant current sources 103-1 to 103-1m are not arranged in the group regions 1100-1 to 1100-1m, respectively, and the heater group, the transistor group, the input / output pad group 1501, Is arranged as a constant current source group in which a plurality of constant current sources are gathered.

  Now, since many heaters are usually arranged from the viewpoint of performing high-speed recording, the length of the head substrate is long in the heater arrangement direction, that is, in the lateral direction in FIG. 8 and FIG. From the viewpoint of reducing the area of the heater, the heater is arranged to be shorter in the direction perpendicular to the heater arrangement direction. Due to this elongated shape, when the length of the head substrate in the direction perpendicular to the heater array is extended, the area of the head substrate is remarkably increased, and the number of head substrates that can be formed on one wafer is remarkably reduced.

  For this reason, according to this embodiment, as few types of circuits and elements as possible are arranged in a region parallel to the heater array (in a direction orthogonal to the heater array direction). In the example shown in FIG. 8, only the number of driving elements (MOS transistors) necessary for the number of heaters and the control circuit for controlling them are arranged, and other circuit elements (for example, constant current source group) and input / output pads are arranged. Are collectively arranged on the substrate end side on the extension line of the heater array, thereby suppressing an increase in the area of the head substrate.

  Specifically, in this embodiment, a constant current source configured with a smaller number of elements than the number of heaters is arranged between the input / output pad portion and the heater arrangement portion, thereby allowing a circuit related to constant current driving. The increase in the substrate size is suppressed.

  Further, the arrangement of the constant current source groups according to the present invention is not only from the viewpoint of preventing the head substrate size from being increased, but also for the following reasons.

  In FIG. 5, in the wiring from the constant current source group to the heaters in each group, there is no difference in voltage drop because there is only one heater that can be driven simultaneously in each group. Since the current flowing through the plurality of groups flows through the wiring to the GND pad 1104, the amount of voltage drop changes depending on the number of heaters that are driven simultaneously. In this embodiment, as shown in FIG. 10, the constant current sources of each group are collectively arranged in a region near the input / output pad (region between the heater group and switching MOS transistor group and the input / output pad). As a result, the distance from the pad to the constant current source is shortened, so that the variation in the amount of voltage drop that occurs in the wiring to the constant current source is also reduced.

  Further, as shown in FIG. 10, since the length of the wiring 1603 from the GND pad to the plurality of constant current sources is substantially equal, the wiring resistance from the GND pad to each constant current source is substantially equal. can do. As a result, the source voltages of the MOS transistors constituting the respective constant current sources can be made equal, which contributes to the driving of a highly reliable and stable MOS transistor.

  Further, as shown in FIG. 10, common wires such as power supply wires 1601-1 to 1601-m and power supply wires 1602-1 to 1602-m from the constant current source group 103 for supplying a predetermined current to each switching MOS transistor. The longer the wiring length is, the wider the wiring is, so that the wiring resistance is substantially equal between the groups. For this reason, it is not necessary to set the voltage so as to have a high wiring resistance, and electrical loss can be reduced.

  FIG. 11 is a diagram showing a layout configuration of the head substrate according to the second embodiment of the present invention.

  FIG. 11 is an example of a layout configuration for realizing the heater driving circuit shown in FIG. In addition, the dashed-dotted line shown by FIG. 11 has shown the axis of symmetry. Therefore, also in FIG. 11, the same reference numerals are given to the same components as mentioned in FIG.

  FIG. 12 is a diagram showing the layout of the power supply wiring of the head substrate shown in FIG.

  The layout of this embodiment is an example in which four heater driving circuits shown in FIG. 5 are arranged symmetrically on the same head substrate. The operation of each circuit is the same as that described in the first embodiment. Therefore, the reference number is attached to only one of the four sections. In this configuration, for example, as shown in FIG. 3, the ink is supplied to the heater disposed on the upper surface of the head substrate from a hole (ink supply ports 2C, 2M, 2Y) formed in the center of the substrate, so that the heater By supplying current, ink can be ejected onto the upper surface of the paper.

  Therefore, with the configuration shown in FIG. 11, current can be supplied to the heater driving circuit, which is four constant current source blocks, and each of the (x × m) heaters included in these blocks ejects the same color ink. The recording head may be configured to be associated with the four groups of nozzle rows, or may be configured to be associated with the four groups of nozzle rows that eject different color inks.

  As shown in FIG. 12, in the configuration according to this embodiment, the length of the power supply wiring from the pads arranged on the left and right (two short sides of the head substrate) is at most the length to the center of the substrate. There is an effect that the voltage drop due to the power supply wiring can be efficiently suppressed.

  Referring to FIG. 11 again, the constant current source group is disposed on the head substrate between the corresponding heater array group and the adjacent pad group. Also in this case, similarly to the first embodiment, an increase in the size of the head substrate due to a circuit related to constant current driving can be suppressed.

  FIG. 13 is a circuit block diagram showing the configuration of the head substrate of the recording head IJH using the constant current driving method according to this embodiment. Also in FIG. 13, the same reference numerals are given to the same components as mentioned in the description so far. In FIG. 13, 1102-11 to 1102-mx are depicted as switches, but as described above, the substance is a MOS transistor that functions as a switching element.

  This circuit configuration is roughly divided into a reference voltage circuit 101, a voltage / current conversion circuit 102, a reference current circuit 103, and n constant current source blocks (heater drive circuits) 106-1 to 106-n. .

  Therefore, with the configuration shown in FIG. 13, current can be supplied to n constant current source blocks (heater driving circuits), and (xxm) heaters included in these blocks receive ink of the same color. It may be associated with n groups of nozzle rows to be ejected, or may be associated with n groups of nozzle rows that eject ink of different colors.

  The reference voltage circuit 101 generates a reference voltage (Vref) used by the voltage / current conversion circuit 102. The voltage-current conversion circuit 102 performs voltage-current conversion based on the reference voltage (Vref) to generate a reference current (Iref). Next, based on the reference current (Iref) generated by the voltage-current conversion circuit 102, the reference current circuit 105 generates a plurality of reference currents IR1 to IRn. A plurality of reference currents IR1 to IRn proportional to the reference current (Iref) current are generated from the reference voltage (Iref) by the current mirror circuit, and the reference currents IR1 to IRn are supplied to the n constant current source blocks 106. To do.

  In the constant current source blocks 106-1 to 106-n, the reference currents IR1 to n are proportional to the reference currents IR1 to n by the constant current source groups 103-1 to 103-m in the respective constant current source blocks with reference to the reference currents IR1 to IRn. Constant currents Iha to m are output. Since the operation in each current source group is the same as that in the first embodiment, the description thereof is omitted.

  FIG. 14 is a diagram showing a layout configuration of a head substrate according to this embodiment.

  FIG. 14 shows an example of a layout configuration for realizing the circuit of the head substrate shown in FIG. In addition, the dashed-dotted line shown by FIG. 14 has shown the axis of symmetry. Therefore, also in FIG. 14, the same reference numerals are given to the same components as mentioned in the description so far.

  In this embodiment, an example having four head drive circuits will be described.

  In the example shown in FIG. 14 as well, as in the second embodiment, each of the four constant current source groups is arranged between the heater array and a pad group adjacent thereto. The reference voltage circuit, current-voltage conversion circuit, and reference current circuit are collectively arranged between the heater array and the pad group.

  In the example shown in FIG. 14, the reference voltage circuit 101, the voltage / current conversion circuit 102, and the reference current circuit 105 are arranged at the same place (area surrounded by a broken line). The heater array and the pad group may be divided and arranged.

  In any case, according to this embodiment, such an arrangement can suppress an increase in the size of the head substrate due to a circuit related to constant current driving as in the first and second embodiments.

  FIG. 15 is a diagram showing an example of a layout configuration in which two circuit configurations shown in FIG. 14 are provided on the same substrate.

  In this example, the currents to be applied to the heaters can be set independently for two systems. For example, an array of heaters suitable for discharging two different amounts of ink can be mixed and configured on the same substrate.

FIG. 16 is a diagram illustrating an example of a layout configuration in which a plurality of heater arrays are arranged.
The configuration of this example is suitable when, for example, a plurality of colors of ink are ejected by a heater provided on the same substrate for color recording.

  15 to 16, ink supply ports 2-1, 2-2,..., 2-n are shown. Since the other components are the same as those already described, the same reference numerals are given and description thereof is omitted.

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. 3 is a perspective view illustrating a three-dimensional structure of a recording head IJHC that discharges three color inks. FIG. 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. It is a fragmentary sectional view of the inkjet recording head using the head substrate shown in FIG. 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 circuit block diagram which shows the structure of the head board | substrate of the recording head IJH using the constant current drive system according to Example 3 of this invention. It is a figure which shows the layout structure of the head substrate according to Example 3 of this invention. FIG. 15 is a diagram illustrating an example of a layout configuration in which two circuit configurations illustrated in FIG. 14 are provided on the same head substrate. It is a figure which shows the layout structure of the head substrate corresponding to a color recording. 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 group of the heater drive circuit shown in FIG. It is the figure which showed the layout of the power supply wiring connected to the groups 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

DESCRIPTION OF SYMBOLS 101 Reference voltage circuit 102 Voltage current conversion circuit 103 Constant current source group 103-1 to 103-m Constant current source 105 Reference current circuit 106-1 to 106-n Current source block 1101-111 to 1101mx Heater 1102-11 to 1102mx MOS Transistor 1105 Control circuit IJH Recording head

Claims (13)

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
The substrate is a substrate having a long side and a short side,
Arranging the plurality of recording elements and the plurality of switching elements in a longitudinal direction of the substrate;
A terminal for inputting a drive signal and a control signal used for driving the plurality of recording elements is arranged at an end portion on a short side of the substrate,
The constant current source for causing the constant current to flow is in a region between a first region in which the terminals are arranged and a second region in which the plurality of recording elements and the plurality of switching elements are arranged. A substrate for a recording head, wherein the substrate is arranged.   2. The recording head according to claim 1, 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. substrate.   The recording head substrate according to claim 1, wherein a supply port for supplying ink is provided in a longitudinal direction of the substrate. The plurality of recording elements are grouped into a plurality of groups, recording elements belonging to the same group are not driven simultaneously, and a plurality of recording elements belonging to different groups are driven simultaneously,
A plurality of the current sources are provided corresponding to each of the plurality of groups,
2. The printhead substrate according to claim 1, wherein the plurality of current sources are collectively arranged in a region between the first region and the second region.   5. The recording head substrate according to claim 4, wherein the constant current source is formed of a MOS transistor that operates in a saturation region.   5. The recording head substrate according to claim 4, wherein distances from the terminals to the plurality of constant current sources corresponding to the plurality of groups are substantially equal. A reference current circuit for generating a reference current used by the constant current source to generate a constant current;
A voltage-current conversion circuit that generates the reference current based on a reference voltage;
A reference voltage circuit for generating the reference voltage;
The recording head according to claim 1, wherein the reference current circuit, the voltage-current conversion circuit, and the reference voltage circuit are disposed between the first region and the second region. Substrate.   A group of circuit elements obtained by disposing the constant current source between the first region and the second region may be at least one of vertically symmetrical and laterally symmetrical on the substrate. The recording head substrate according to claim 2, wherein a plurality of the recording head substrates are arranged.   The print head substrate according to claim 1, wherein the plurality of switching elements are MOS transistors.   A recording head using the recording head substrate according to claim 1.   The recording head according to claim 10, wherein the recording head is an ink jet recording head that performs recording by discharging ink. 12. A head cartridge comprising an ink tank integrally holding ink supplied to the ink jet recording head according to claim 11. A recording apparatus that performs recording by discharging ink onto a recording medium using the inkjet recording head according to claim 11 or the head cartridge according to claim 12.

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