JP2007203573A - Inkjet head unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an inkjet head unit in which abnormal connection of a flexible cable and an abnormal cable can be judged through a simple arrangement. <P>SOLUTION: Dummy conductors 8 and 9 are arranged at the opposite outside edges of a flexible cable 3, and their one ends are connected on an ink jet head 1 to form a single current passage via the ink jet head 1. Ground potential is applied, for example, to one end of the current passage on a head control substrate 2 and the voltage level at the other end is monitored by an abnormal connection detection circuit 11. Since only one abnormal connection detection circuit is required, abnormality in connection of a flexible cable and abnormality in cable (disconnection) can be judged through a simple arrangement. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inkjet head device.

  Ink droplet ejection methods for inkjet head devices include bubbles that generate bubbles in ink liquid using thermal energy, a method that uses pressure waves generated by the bubbles, a method that uses electrostatic force, and a piezo (piezoelectric thin film element). There are various methods such as a method using a pressure wave by a simple vibrator.

  By the way, an inkjet head device is composed of an inkjet head that ejects ink droplets and a head control board that is equipped with a control circuit that controls the ink droplet ejection operation of the inkjet head. In consideration of the above, both are configured to be separable. Specifically, a configuration is adopted in which one end of a flexible cable is fixedly connected to the inkjet head, and the other end of the flexible cable is connected to a head control board by a connector.

  The flexible cable may be mounted with a driving IC that drives the ink droplet ejection portion of the inkjet head in accordance with an ink droplet ejection control signal from a control circuit mounted on the head control board.

  However, in the connector connection method described above, there is a risk that the connector connection is accidentally disconnected during the head assembly operation, and thus, conventionally, a connector with a lock is often used. Since this leads to an increase in device cost and an increase in the size of the area around the connector connection portion, improvement is desired.

  On the other hand, a method disclosed in, for example, (Patent Document 1) is known as a method for detecting an abnormality in a connection cable between electric circuits or devices. The outline will be described below with reference to FIG.

  FIG. 6 is a diagram illustrating a configuration example for detecting an abnormality in a conventional connection cable. In FIG. 6, the connection cable 101 has one end connected to the circuit board 102 and the other end connected to a circuit board or device (not shown). In this connection cable 101, a plurality of original connection conductors 103 are arranged in parallel, but dummy conductors 104 and 105 are added along both outer edges thereof.

  One end of each of the dummy conductors 104 and 105 is connected to one input terminal of a comparator 106 and 107 that is a detection circuit provided on the circuit board 102, and the other end of each of the dummy conductors 104 and 105 is a circuit board (not shown). Or connected to ground potential in the device. The comparators 106 and 107 have one input terminal connected to the power supply via a resistance element and the other input terminal connected to the ground potential.

  According to this configuration, if there are no breaks in the dummy conductors 104 and 105, the comparators 106 and 107 set the output to either the H level or the L level. When one or both of the dummy conductive wires 104 and 105 are disconnected, the corresponding one of the comparators 106 and 107 sets the output to the other level of the H level and the L level. Thereby, disconnection of the connection cable 101 can be detected.

In this example, the disconnection is detected. However, in the inkjet head device, a connector connection failure can be detected in addition to the disconnection.
Japanese Utility Model Publication No. 63-135174

  However, the above-described conventional abnormality detection method requires a detection circuit for each of the two dummy conductors, and when applied to an inkjet head device, it is necessary to devise from the viewpoint of reducing the device cost and miniaturization. .

  The present invention has been made in view of the above, and an object of the present invention is to obtain an inkjet head device having a mechanism capable of detecting a flexible cable connection abnormality and a cable abnormality with a simple configuration.

  In order to achieve the above-described object, according to the present invention, an inkjet head having a plurality of ink droplet ejection units for ejecting ink droplets and each output terminal of a control circuit for controlling the plurality of ink droplet ejection units are connected. A flexible cable having a head control board on which a connector is mounted and a terminal connected to the connector on the head control board at one end, and is in a one-to-one relationship with each ink droplet ejection portion of the inkjet head. One end side of a large number of connection conductors arranged in parallel to each other is fixedly connected to a corresponding ink droplet discharge portion of the inkjet head, and each other end side of the large number of connection conductors is connected to the terminal. An inkjet head device comprising a cable, wherein each end of the flexible cable is the inkjet head Dummy conductors connected to the terminals together with the plurality of connection conductors are disposed along the outer edges, respectively, and the head control board monitors the voltage level of the input signal. A connection abnormality detection circuit is provided, and one of the connection parts for the dummy conductors provided in the connector is connected to the ground potential or a predetermined positive potential of the head control board, and the other connection part is connected It is connected to the connection abnormality detection circuit that monitors the voltage level.

  According to the present invention, the flexible cable is provided with dummy conductors on both outer edges, and they form a single current path via the inkjet head. In the head control board, a ground potential or a predetermined positive potential is applied to one end of the current path and the voltage level at the other end is monitored, so that only one abnormality detection circuit can be used. It is possible to determine the flexible cable connection abnormality and cable abnormality by the configuration.

  According to the present invention, it is possible to determine a flexible cable connection abnormality or a cable abnormality with a simple configuration.

  Exemplary embodiments of an ink jet head device according to the present invention will be described below in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a diagram illustrating an overall configuration of a flexible cable connection abnormality detection mechanism provided in the inkjet head device according to the first embodiment of the present invention. As shown in FIG. 1, the ink jet head device according to the first embodiment has a configuration in which an ink jet head 1 a and a head control board 2 are detachably connected by a flexible cable 3.

  The inkjet head 1a is provided with a plurality of ink droplet ejection sections 4 that eject ink droplets. Each ink droplet discharge unit 4 is led out to the boundary with the flexible cable 3 by a lead wire 4a. A connecting wire 10 is provided outside the lead wire 4a. In this embodiment, each ink droplet ejection unit 4 includes, for example, a piezo actuator and a nozzle.

  The head control board 2 is mounted with a control circuit (not shown) for controlling the ink droplet ejection operation of the inkjet head 1a and a flexible cable connector 5 as a connector. A control circuit (not shown) includes an output terminal that outputs an ink droplet ejection operation control signal in a one-to-one relationship with each ink droplet ejection unit 4 of the inkjet head 1a. The flexible cable connector 5 is connected to each output end of the control circuit (not shown).

  The flexible cable 3 has a connection terminal 6 fitted to the flexible cable connector 5 on the head control board 2 at one end, and has a large number of connection conductors in a one-to-one relationship with each ink droplet ejection portion 4 of the inkjet head 1a. 7 are arranged in parallel on a plane. Each one end side of the large number of connection conductors 7 is fixedly connected to a lead wire 4a to the corresponding ink droplet discharge portion 4 of the inkjet head 1a (see FIG. 2), and each other end side is a connection terminal. 6 is connected.

  In the first embodiment, the flexible cable 3 has dummy conductors 7 and 8 arranged along both outer edges. One end of each of the dummy conducting wires 8 and 9 is connected via a connecting conducting wire 10 provided in the ink jet head 1 a, and each other end is connected to the connecting terminal 6 together with a large number of connecting conducting wires 7. That is, the dummy conductors 8 and 9 form a single current path via the connection conductor 10 of the inkjet head 1a.

  Further, the head control board 2 is provided with a connection abnormality detection circuit 11 for monitoring the voltage level of the input signal, and one of the connection portions for the dummy conductors provided in the flexible cable connector 5 (see FIG. In the example shown, the connecting portion for the dummy conducting wire 8) is connected to the ground potential of the head control board 2 or a predetermined positive potential (ground potential in the illustrated example), and the other connecting portion (the connecting portion for the dummy conducting wire 9 in the illustrated example). ) Is connected to the connection abnormality detection circuit 11.

  The connection abnormality detection circuit 11 can be constituted by a comparator 11a, for example. One input terminal of the comparator 11a is connected to a connection portion for the dummy conductor 9 in the flexible cable connector 5, and since the connection portion for the dummy conductor 8 is at the ground potential, the power supply is provided via the resistance element 11b. Is connected, and a ground potential is connected to the other input terminal of the comparator 11a.

  Next, FIG. 2 is a sectional view showing a fixed connection structure between the inkjet head and the flexible cable shown in FIG. In FIG. 2, one end of all the conducting wires 13 including a large number of connecting conductors 7 and dummy conducting wires 8 and 9 arranged in the flexible cable 3 is connected to each ink droplet discharge portion 4 of the inkjet head 1a. And all the conducting wires 12 including the connecting conducting wire 10 are joined by an anisotropic conductive sheet 14 so as not to be separated. The cover resin 15 is covered except for the joining ends of all the conducting wires 12 on the ink jet head 1a. Further, the cover resin 16 is covered except for the joining ends on all the conductive wires 13 on the flexible cable 3.

  Next, the operation of the connection abnormality detection mechanism of the flexible cable 3 configured as described above will be described. When the flexible cable connector 5 on the head control board 2 and the connection terminal 6 attached to the flexible cable 3 are correctly connected, the other end of the dummy conductor 8 is connected to the ground potential in the head control board 2. Therefore, one input terminal of the comparator 11a to which the other end of the dummy conducting wire 9 is connected is drawn to the ground potential. In this case, the output level of the comparator 11a is either the H level or the L level. This is the normal output level.

  On the other hand, the connection terminal 6 was removed from the flexible cable connector 5 at the time of maintenance work, etc., but it was left unplugged due to other work being taken care of, or the work to return to the original was insufficient. When an abnormality occurs such as a connection failure on the conductor 8 side or the dummy conductor 9 side, or a break in one or both of the dummy conductors 8, 9, one input terminal of the comparator 11a is connected to the ground potential. At this time, the power supply potential level is not obtained. In this case, the output level of the comparator 11a is either the H level or the L level. This is the output level at the time of abnormality.

  Therefore, by monitoring the output state of the comparator 11a, it is possible to determine the suitability of the connection state between the flexible cable connector 5 and the connection terminal 6 and the cable abnormality.

  As described above, according to the first embodiment, the flexible cable 3 is provided with the dummy conductors on both outer edges, respectively, so that they form a single current path via the inkjet head, In the head control board, a ground potential or a predetermined positive potential is applied to one end of this current path, and the voltage level at the other end is monitored, so only one abnormality detection circuit can be used. A connection abnormality of the flexible cable 3 or a cable abnormality can be determined.

(Embodiment 2)
FIG. 3 is a diagram illustrating an overall configuration of a flexible cable connection abnormality detection mechanism provided in the inkjet head device according to the second embodiment of the present invention. In FIG. 3, the same reference numerals are given to components that are the same as or equivalent to the components shown in FIG. 1 (Embodiment 1). Here, the description will be focused on the portion related to the second embodiment.

  As shown in FIG. 3, in the ink jet head device according to the second embodiment, the flexible cable 20 in which the reference numeral is changed in the configuration shown in FIG. It is mounted in a shape that runs vertically in the width direction. Further, in the ink jet head 1b whose code is changed, the connecting conductor 10 shown in the ink jet head 1a is deleted.

  In FIG. 3, a large number of connection conductors 7 arranged in parallel on a plane are connected in a one-to-one relationship between the output end of the driving IC 21 and each ink droplet ejection section 4 of the inkjet head 1b. The connection conductor 7a is divided into two, and the connection conductor 7b connecting the input terminal of the driving IC 21 and the connection terminal 6 is divided into two. Note that the number of connecting conductors is such that the connecting conductor 7a> the connecting conductor 7b.

  In this embodiment, the driving IC 21 is a piezo driving IC that drives the piezo actuator of each ink droplet ejection unit 4 in accordance with an ink droplet ejection operation control signal from a control circuit (not shown) on the head control board 2. .

  Further, in the configuration shown in FIG. 1 (Embodiment 1), dummy conductors 22 and 23 are provided in place of the dummy conductors 8 and 9. One end of each of the dummy conductors 22 and 23 is connected in the arrangement region of the driving IC 21 using the connection conductor 24 (see FIG. 4), and each other end is connected to a large number of connection conductors as in the first embodiment. It is connected to the connection terminal 6 together with 7b.

FIG. 4 is a plan view showing a wiring state of the dummy conductors passing through the place where the driving IC shown in FIG. 3 is arranged. FIG. 5 is a perspective view showing a mounting mode of the driving IC shown in FIG. FIGS. 4 and 5 are diagrams for explaining the manufacturing in this order. As shown in FIG. 4, a large number of pad terminals 30 and 31 are provided at the placement location of the driving IC set on the flexible cable 20. The flexible cables 20 are arranged in parallel in the width direction. The corresponding ones of the connection conductors 7b on the connection terminal 6 side are connected to the numerous pad terminals 30. Further, the corresponding ones of the connection conductors 7a on the ink jet head 1b side are connected to the many pad terminals 31.

  The ends of the dummy conductors 22 and 23 facing between the pad terminals 30 and 31 arranged in parallel in the width direction of the flexible cable 20 are connected by a connection conductor 24 passing between the pad terminals 30 and 31. , Forming a single current path.

  As shown in FIG. 5, the driving IC 21 is flip-chip mounted on the pad terminals 30 and 31. The connecting conductor 24 is in a state of being disposed directly under the driving IC 21. Since there is a sufficient gap between the bottom surface of the driving IC 21 and the flexible cable 20 so that the connecting conductor 24 is not brought into contact with the bottom surface of the driving IC 21, the connecting conductor 24 is electrically insulated. It is arranged in the state.

  In the above configuration, also in the second embodiment, when the flexible cable connector 5 on the head control board 2 and the connection terminal 6 attached to the flexible cable 20 are correctly connected, other than the dummy conductor 22 Since the end is connected to the ground potential in the head control board 2, one input end of the comparator 11a to which the other end of the dummy conducting wire 23 is connected is drawn to the ground potential. In this case, the output level of the comparator 11a is either the H level or the L level. This is the normal output level.

  On the other hand, the connection terminal 6 was removed from the flexible cable connector 5 at the time of maintenance work, etc., but it was left unplugged due to other work being taken care of, or the work to return to the original was insufficient. If an abnormality occurs such as a connection failure on the conductor 8 side or the dummy conductor 9 side, or disconnection on one or both of the dummy conductors 8, 9, one input terminal of the comparator 11a is connected to the ground potential. At this time, the power supply potential level is not obtained. In this case, the output level of the comparator 11a is either the H level or the L level. This is the output level at the time of abnormality.

  Therefore, as in the first embodiment, by monitoring the output state of the comparator 11a, it is possible to determine the suitability of the connection state between the flexible cable connector 5 and the connection terminal 6 and the cable abnormality.

  As described above, according to the second embodiment, the flexible cable is provided with the dummy conductor wires on both outer edges, but the head-side connection terminal and the board-side connection terminal of the driving IC arranged in the middle. Since a single current path is formed by connecting both dummy conductors through the gap, the flexible cable can be configured with a simple configuration as in the first embodiment. Connection abnormality and cable abnormality can be determined.

  In each of the embodiments, the piezo method is used as the ink droplet ejection method. However, the present invention can be similarly applied to other ink droplet ejection methods. Further, the method for processing one dummy lead on the head control board side and the voltage level monitoring method for the other dummy lead are not limited to the above-described embodiments.

  In each embodiment, the connection abnormality detection circuit is provided on the head control board. However, the connection abnormality detection circuit may be provided on a place other than the head control board.

  As described above, the ink jet head device according to the present invention is useful for determining a flexible cable connection abnormality or a cable abnormality with a simple configuration.

The figure which shows the whole structure of the connection abnormality detection mechanism of the flexible cable with which the inkjet head apparatus by Embodiment 1 of this invention is provided. Sectional drawing which shows the fixed connection structure of the inkjet head and flexible cable shown in FIG. The figure which shows the whole structure of the connection abnormality detection mechanism of the flexible cable with which the inkjet head apparatus by Embodiment 2 of this invention is provided. The top view which shows the wiring condition of the dummy conducting wire which passes through the arrangement place of the drive IC shown in FIG. The perspective view which shows the mounting aspect of driving IC shown in FIG. The figure which shows the structural example which performs abnormality detection with the conventional connection cable

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b Inkjet head 2 Head control board 3 Flexible cable 4 Ink droplet discharge part 4a Lead wire for ink drop discharge part 5 Flexible cable connector (first connector) on the head control board
6 Connection terminal attached to the flexible cable (second connector)
7, 7a, 7b Connection conductor 8, 9 Dummy conductor 10 Connection conductor 11 Connection abnormality detection circuit 11a Comparator 11b Resistance element 12 All conductors on inkjet head 13 All conductors on flexible cable 14 Anisotropic conductive sheet 15, 16 Cover resin 20 Flexible cable 21 Driving IC (piezo driving IC)
22, 23 Dummy conductor 24 Connection conductor 30, 31 Pad terminal

Claims (3)

An inkjet head having a plurality of ink droplet ejection units for ejecting ink droplets; a head control board on which a connector to which each output terminal of a control circuit for controlling the plurality of ink droplet ejection units is connected; A flexible cable having a terminal connected to the connector on the head control board, and a plurality of connection conductors arranged in parallel on a plane in a one-to-one relationship with each ink droplet discharge portion of the inkjet head. In an inkjet head device comprising: a flexible cable in which each one end side is fixedly connected to a corresponding ink droplet discharge portion of the inkjet head, and each other end side of the plurality of connection conductors is connected to the terminal;
The flexible cable has one end connected via the inkjet head, and the other end connected to the terminal together with the multiple connection conductors, and dummy conductors connected to the terminals, respectively. An ink jet head device. An ink-jet head having a plurality of ink droplet ejection units for ejecting ink droplets; and a head control board on which a connector to which each output terminal of a control circuit for outputting a drive control signal for the plurality of ink droplet ejection units is connected is mounted; A flexible cable having a terminal connected to the connector on the head control board at one end and a driving IC connected to the terminal at an input end of the drive control signal in the middle of the inkjet cable One end side of a large number of connection conductors arranged in parallel on a plane in a one-to-one relationship with each ink droplet ejection portion of the head is fixedly connected to the corresponding ink droplet ejection portion of the inkjet head, An inkjet head device comprising: a flexible cable connected to the corresponding output end of the driving IC at each other end of the connecting conductor Stomach,
The flexible cable has one end connected within the arrangement area of the driving IC, and the other end has dummy conductors that are connected to the terminals together with the multiple connection conductors along the outer edges. An ink jet head device. A connection abnormality detection circuit for monitoring the voltage level of the input signal is provided, and one of the connection parts for the dummy conductors provided in the connector is set to the ground potential of the head control board or a positive predetermined potential. The inkjet head device according to claim 1, wherein the other connection portion is connected to the connection abnormality detection circuit that monitors the voltage level.

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