JP2009262486A - Circuit board and liquid delivering apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that variation of the working accuracy of wiring of a power supply wiring line to a heating element becomes relatively large following the fact that a wiring width is made fine. <P>SOLUTION: In the circuit board where a circuit with both a plurality of the heating elements 12 and block wiring lines 1-1 to 1-n connected in common to one end part of each heating element group of a plurality of heating elements divided into a plurality of groups is provided on a substrate, at least a part of the block wiring lines is electrically connected to the heating element group by joining after separating one ends from a terminal on the circuit board to two or more wiring lines. Heat generated by the heating elements 12 of the circuit board is utilized to make a liquid delivered, whereby the liquid delivering apparatus is constructed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a circuit board provided with a plurality of heating elements. In particular, the present invention relates to a circuit board for a liquid discharge apparatus that converts electric energy into heat energy by a heating element and discharges liquid using the heat energy.

  Hereinafter, a conventional circuit board will be described by taking an inkjet head as an example.

  In an ink jet recording apparatus, an image can be recorded by discharging ink as fine droplets from a discharge port to a recording member. The principle will be described. Electric energy is converted into heat energy by a heating element, and bubbles are generated in the ink by the heat energy. Due to the action of the bubbles, droplets are ejected from the ejection port at the tip of the liquid ejection head, and adhere to the recording member to record an image. Therefore, such a liquid discharge head has a circuit board provided with a plurality of heating elements that convert electrical energy into thermal energy.

  Specifically, after a resistance layer and an electrode material layer are formed on an insulating surface, a part of the electrode material layer is removed to form a pair of electrodes, and a space between the electrodes becomes a heat generating portion. Thereafter, a protective layer for protecting these from ink and a cavitation-resistant film for protecting the protective layer from chemical or physical damage accompanying heat generation are formed.

  A circuit board for a liquid ejecting apparatus has a plurality of heating elements as described above at a high density, and enables image recording. Each heating element is connected in series with a power transistor (not shown) that controls on / off of the current flowing through the heating element. In addition, a discharge port is formed on the circuit board to form a liquid discharge device.

  In recent years, with respect to each of the above-described heating elements, it has been required to narrow the pitch between the heating elements and perform high density printing with small droplets. For this reason, there is a tendency that the drive circuit including the heating element and the power transistor is miniaturized and the number of the heating elements is increased.

  The configuration of a conventional circuit board will be described with reference to FIGS. FIG. 8 is a circuit diagram of the circuit board described in FIG. One end of each of the heating elements R1 to R128 is connected to the block wiring for each block via a diode. The block wiring is connected to digit terminals (power supply terminals) DG0 to DG15. The other ends of the heating elements R1 to R128 are connected to the segment terminals Seg0 to Seg7 for each block.

By the way, in the block wiring as shown in FIG. 8, since the distance from the power supply terminal is different in each block, the wiring width is adjusted according to each block wiring distance so that the wiring resistance of each block becomes the same. (FIG. 9).
JP-A-2-217253

  However, as the minimum line width becomes narrower, the wiring resistance value of the block wiring that frequently uses the minimum line width varies greatly due to processing variations. On the other hand, in the block wiring that uses only a line width much larger than the minimum line width, the fluctuation of the wiring resistance value is small even if there is a variation in processing. For this reason, there is a problem that the wiring resistance value differs depending on the processing variation between the block wirings, the current value when the same voltage is applied to the heating element and heated, and the heating temperature varies. (FIG. 10).

  In view of the above problems, an object of the present invention is to provide a circuit board that can suppress variation in resistance value between blocks even when there is variation in processing. It is another object of the present invention to provide a circuit board for a liquid ejecting apparatus that ejects a high-quality liquid whose heating temperature is constant when the same voltage is applied to the heat generating elements and heated.

In order to achieve the above object, a circuit board according to the present invention includes a plurality of heating elements and wiring commonly connected to one end of each heating element group of the plurality of heating elements divided into a plurality of groups. In a circuit board provided on the substrate,
At least a part of the wiring is separated from the terminal on the substrate at one end into two or more wirings, and then joined to be electrically connected to the heating element group.

A liquid ejection apparatus according to the present invention includes the above circuit board, and the liquid ejection apparatus ejects liquid using heat generated by the heating element of the circuit board.
A grooved member provided corresponding to the heat generating element and provided with a discharge port for the liquid and a flow path for supplying the liquid onto the heat generating element;
A power supply circuit for supplying a power supply voltage to the circuit board;
It is characterized by having.

  According to the present invention, when the same voltage is applied to the heating element and heated, the heating temperature can be made substantially constant at low cost. When the circuit board of the present invention is used as a circuit board for a liquid ejecting apparatus, it is possible to provide a liquid ejecting apparatus that ejects a high-quality liquid.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view of a block wiring portion extracted from a circuit board according to an embodiment of the present invention.

The circuit board is formed by forming a resistance layer such as TaSiN and TaN and an electrode material layer such as Al, Al-Si, and Al-Si-Cu on the insulating surface of the substrate, and then removing a part of the electrode material layer to form a pair An electrode is formed and produced. And between these electrodes becomes a heat generating part, and becomes a heat generating element. A substrate having an insulating surface can be configured, for example, by thermally oxidizing a Si substrate to form a SiO ₂ film. A switch element such as a transistor connected to the heating element is formed on the Si substrate.

  There are provided n block wirings (n is a natural number of 2 or more) from 1-1 to 1-n as power wirings. Each block wiring is connected to a plurality of heating elements 12 constituting a heating element group and a plurality of switch elements 11 connected to the plurality of heating elements 12, respectively. Here, the details of the wiring on the GND side are omitted. The GND wiring may be a common wiring, or may be a block wiring having the same configuration as the block wirings 1-1 to 1-n. The low potential side may be a fixed potential even if it is not GND.

  In the first block wiring 1-1, the length of the wiring 13 from the power supply terminal to the end of the heating element (wiring length L) is 200 μm, and the wiring having a wiring width of 2 μm is connected by one. The distance from the power terminal to the end of the heating element of the nth block wiring 1-n is (200 × n) μm. The n-th block wiring 1-n is connected in parallel with n wirings each having a wiring length (200 × n) μm and a wiring width 2 μm. Although not shown here, the k-th (<1k <n) block wiring 1-k is connected in parallel with k wirings having a wiring length (200 × k) μm and a wiring width of 2 μm.

  FIG. 2 shows the configuration of FIG. 1 as an electric circuit diagram. Of the heating elements connected to each block, the resistance of one heating element is r (Ω), and the wiring resistance value of the first block wiring of the block wiring (L) 200μm and wiring width 2μm is R1 (Ω). Also, the on resistance of each switch element and the wiring resistance at the end of the heating element are sufficiently small and can be ignored.

When the power supply voltage is VH (V) and the current value when one heating element of the first block wiring is driven is I1,
I1 = VH / (r + R1)
Can be described.

  The wiring resistance value Rn of the nth block wiring 1-n is

(Equation 1)
n
1 / Rn = Σ (1 / (n ・ R1) = 1 / R1
1
Can be described. That is, one wiring is the wiring resistance R1 · n, which is connected in parallel to form the nth block wiring 1-n, and has the same wiring resistance as the first block wiring 1-1. The value is R1.

Similarly, when one heat generating element is driven for the nth block wiring, the current value In (A) is
In = VH / (r + Rn) = VH (r + R1) = I1
It becomes.

  For this reason, the current that flows when one heating element is driven in any block is the same.

  Next, an example will be described in which variation in wiring processing occurs in the block wiring of FIG. 1 and the designed minimum line width of 2 μm becomes 2.5 μm.

At this time, the wiring resistance value R1 ′ (Ω) of the first block wiring having a wiring length of 200 μm and a wiring width of 2.5 μm is
R1 '= 2 / 2.5 R1 = 0.8R1
It becomes. The current value I1 ′ (A) when one heating element connected to the first block wiring is driven is
I1 '= VH / (r + R1') = VH / (r + 0.8R1)
It becomes.

In addition, the wiring resistance value Rn ′ of the nth block wiring is the same wiring resistance value R1 ′ as that of the first block wiring 1-1. The current value In ′ (A) when one heating element connected to the nth block wiring is driven is
In '= VH / (r + Rn') = VH / (r + R1 ') = VH / (r + 0.8R1) = I1'
It becomes. Therefore, even if the wiring width fluctuates, the current that flows when one heating element is driven in any block is the same.

  In the present embodiment, the minimum line width is 2 μm and the length of the block wiring is a multiple of 200 μm, but it goes without saying that the minimum line width and the length of the block wiring are not specified.

  An example in which the wiring length of the nth block wiring is (200 × n) μm, the number of wirings (n / 2), and the wiring width of 2 μm is connected in parallel to the end of the heating element will be described. Similarly, the first block wiring has a wiring resistance of R1 (Ω) with a wiring length of 200 μm and a wiring width of 2 μm.

  In order for the wiring resistance value Rn of the nth block wiring to be R1, if one wiring resistance value of the nth block wiring is R,

(Equation 2)
n / 2
1 / Rn = Σ (1 / (n ・ R1) = 1 / 2R1
1
Thus, it can be seen that the wiring resistance value Rn is twice R1. However, when the number of wirings of the nth block wiring is one, the wiring resistance value is n · R1. Therefore, if n> 3, the wiring resistance value of the block wiring is reduced even if the number of wirings connected in parallel is reduced. You can see that it can be made smaller.

3 and 4 are diagrams showing a configuration example of the circuit board of the present embodiment. 3 and 4, reference numeral 20 denotes a Si substrate having a SiO ₂ surface formed thereon, 21 denotes a common wiring terminal serving as a GND terminal, and 22 denotes a driving unit including a transistor serving as a switch. This drive unit is formed on the Si substrate. A current flows to a necessary heating element by the drive unit. Reference numeral 23 denotes a block wiring terminal serving as a power supply terminal, reference numerals 24 and 25 denote block wiring (here, only block wiring at both ends is shown), and reference numeral 26 denotes a heating element. Block wiring is commonly connected to the block wiring terminals. Each block wiring is commonly connected to one end of the heating element group. As shown in FIG. 3 and FIG. 4, the block wiring terminal 23 on the substrate is split into one or more wires and then joined to be electrically connected to the heating element group. As shown in FIG. 3, even if a part of the block wiring is parallel wiring (wiring form that merges after being separated), it may be parallel wiring up to the L-shaped portion as shown in FIG. Although the GND wiring is a common wiring here, it may be a block wiring having the same configuration as the block wirings 24 and 25.

  Further, the block wiring in FIG. 1 is a schematic diagram and does not prescribe the routing of the wiring to the last.

  In addition, it is not necessary to match the resistance with the number of wires in accordance with the minimum line width for all the blocks, and within the range of the drive current of the heating element between the blocks, the number of divided block wires, It is possible to change the connection method.

  Next, the configuration of the liquid ejection apparatus using the circuit board of this embodiment will be described.

  In the liquid discharge head according to the embodiment of the present invention, a heating resistor having a heating resistor layer is first formed on the insulating layer of the semiconductor substrate according to the present embodiment described above. Then, in order to form a discharge port and a liquid passage communicating therewith, it can be produced by combining a discharge port forming member such as a top plate made of a molding resin or a film with a heating resistor. When a storage container for storing ink is connected and mounted on the printer main body, a power supply voltage is supplied from the power supply circuit of the main body and image data is supplied from the image processing circuit to the head, the printer operates as an ink jet printer.

  FIG. 5 is a view for explaining an embodiment of the liquid ejection apparatus of the present invention, and shows a part of the liquid ejection head.

  On the element substrate 152 serving as the circuit board shown in the present embodiment, heat is generated by receiving an electric signal through which a current flows, and electric heat for discharging ink from the discharge port 153 by bubbles generated by the heat. The conversion elements 141 are arranged in a plurality of rows. Each of the electrothermal conversion elements is provided with a wiring electrode 154 for supplying an electric signal for driving each electrothermal conversion element, and one end side of the wiring electrode is electrically connected to the switch element 41 described later. It is connected to the.

  A flow path 155 for supplying ink to the ejection port 153 provided at a position facing the electrothermal converter 141 is provided corresponding to each ejection port 153. Walls constituting the discharge port 153 and the flow path 155 are provided in the grooved member 156. By connecting these grooved members 156 to the element base 152, the flow path 155 and a plurality of flow paths are formed. A common liquid chamber 157 for supplying ink is provided.

  FIG. 6 shows the structure of a liquid discharge head in which the element substrate 152 of this embodiment is incorporated. The element substrate 152 is incorporated in a frame 158. On the element substrate, the above-described members 156 constituting the discharge ports 153 and the flow paths 155 are attached. A contact pad 159 for receiving an electrical signal from the apparatus side is provided, and electrical signals as various drive signals are supplied from the controller of the apparatus body to the element base 152 via the flexible printed wiring board 160. The

  FIG. 7 is a view for explaining an embodiment of a liquid ejection apparatus to which the liquid ejection head of the present invention is applied, and shows an overview of the ink jet recording apparatus IJRA.

  The carriage HC that engages with the helical groove 5004 of the lead screw 5005 that rotates via the driving force transmission gears 5011 and 5009 in conjunction with forward and reverse rotation of the drive motor 5013 has a pin (not shown). It is reciprocated in the directions of arrows a and b.

  Reference numeral 5002 denotes a paper pressing plate that presses the paper against the platen 5000 serving as a recording medium conveying unit in the carriage movement direction. Reference numerals 5007 and 5008 denote home position detection means for confirming the presence of the carriage lever 5006 in this region by a photocoupler and switching the rotation direction of the motor 5013 and the like. 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 cap opening 5023. 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. The lever 5012 moves with the movement of the cam 5020 engaged with the carriage, and the driving force from the drive motor is controlled by 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 5005 when the carriage comes to the home position side region. Any operation can be applied to this example as long as the operation is performed. Each of the above-described configurations is an excellent configuration whether viewed alone or in combination, and shows a preferable configuration example for the present invention.

  The apparatus has a controller drive signal supply means (not shown) including an electric circuit for supplying a power supply voltage, an image signal, a drive control signal, and the like to the element base 152.

  Further, the present invention is not limited to the various embodiments described above, and it is obvious that the constituent elements of the present invention can be replaced with alternatives or equivalents as long as the above-described problems can be solved.

  The present invention is used for a circuit board for a liquid ejection apparatus. More specifically, it can be used for a circuit board for an ink jet printer.

It is a figure which shows the outline of the block wiring structure of an Example. It is a figure shown about the electrical connection of FIG. It is a figure which shows the structural example of the circuit board of this embodiment. It is a figure which shows the other structural example of the circuit board of this embodiment. It is a conceptual diagram for demonstrating one Embodiment of the liquid discharge head of this invention. It is a conceptual diagram which shows the structure of the liquid discharge head incorporating the circuit board of this invention. It is a conceptual diagram which shows one Embodiment of the liquid discharge apparatus with which the liquid discharge head of this invention is applied. It is a figure which shows the arrangement | sequence in the block of the conventional heat generating element. It is a figure which shows the block wiring of the circuit containing the conventional heat generating element. It is a figure which shows the process variation of the block wiring of the circuit containing the conventional heat generating element.

Explanation of symbols

1-1 to 1-n Block wiring 12 Heating element 13 Wiring

Claims (4)

In a circuit board provided on a substrate, a circuit having a plurality of heating elements and a wiring commonly connected to one end of each heating element group of the plurality of heating elements divided into a plurality of groups ,
A circuit board, wherein at least a part of the wiring is separated from a terminal on the substrate at one end into two or more wirings and then joined to be electrically connected to the heating element group.   2. The circuit board according to claim 1, wherein when the wiring length of the shortest wiring among the plurality of wirings connected to the plurality of heating element groups is L, the wiring length of the other wiring is (N × L) (n is a natural number of 2 or more), and the number of wirings to be separated is n.   The circuit board, wherein the other end of the plurality of heating elements is connected to a switch element. A liquid ejection apparatus comprising the circuit board according to claim 1, wherein the liquid ejection apparatus ejects liquid using heat generated by a heating element of the circuit board.
A grooved member provided corresponding to the heat generating element and provided with a discharge port for the liquid and a flow path for supplying the liquid onto the heat generating element;
A power supply circuit for supplying a power supply voltage to the circuit board;
A liquid ejecting apparatus comprising:

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