JP4887870B2 - Capacitive load drive diagnosis apparatus, capacitive load drive diagnosis method, and droplet discharge apparatus - Google Patents

Description

  The present invention relates to a capacitive load drive diagnostic device, a capacitive load drive diagnostic method, and a droplet discharge device for diagnosing capacitive load drive.

  Conventionally, a droplet discharge device for discharging ink droplets has been used in a printing device or the like, and a capacitive load such as a piezo element has been used for discharging the droplets. For example, Patent Document 1 below discloses an ink jet recording head driving method and driving apparatus that selectively supplies a desired driving waveform to a piezoelectric element via a plurality of switches.

In order to obtain a uniform and stable image quality with such a printing apparatus, the characteristics of the ejector of the ink droplet composed of piezo elements and the like are electrically diagnosed, and the drive condition of the ejector is corrected based on the diagnosis result. is required. Further, in order to diagnose the characteristics of the ejector, it is necessary to accurately measure the drive waveform applied to the ejector.
JP 2001-26102 A

  However, in the conventional technique, the drive waveform applied to the ejector is measured via a drive circuit that supplies the drive waveform. However, accurate measurement is possible due to the influence of parasitic elements (such as resistance components). There was a problem that it was difficult.

  Further, when the number of capacitive loads constituting the ejector is increased, there is a problem that it is difficult to measure for each capacitive load.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a capacitive load drive diagnostic apparatus and a capacitive load capable of improving the measurement accuracy of drive waveforms applied to a large number of capacitive loads. It is an object to provide a drive diagnosis method and a droplet discharge device.

  In order to achieve the above object, the present invention is a capacitive load drive diagnostic apparatus, comprising: a plurality of switch elements that apply a drive signal having a predetermined waveform to a capacitive load; and a switch element connected to the capacitive load. A voltage for supplying a diagnostic voltage signal from one, and a voltage for detecting the voltage waveform by acquiring the diagnostic voltage signal from a switch element different from the switch element to which the diagnostic voltage signal is applied Waveform detection means and conduction control means for bringing the two switch elements into conduction at the same time are provided.

  Here, a plurality of capacitive loads are provided, and the conduction control means sets all the switch elements for applying a diagnostic voltage signal to each capacitive load in a conductive state, and outputs the diagnostic voltage signal. The switch element for obtaining may be individually in a conductive state for each capacitive load.

  A plurality of the capacitive loads are provided, and the conduction control means is configured to apply the diagnostic voltage signal to the capacitive loads and the switch for obtaining the diagnostic voltage signal. The element may be individually connected to each capacitive load.

  In addition, the capacitive load drive diagnosis device diagnoses the drive of the capacitive load used in the droplet discharge device.

  The present invention also relates to a capacitive load drive diagnosis method, the step of applying a diagnostic voltage signal to the capacitive load from one of a plurality of switch elements that apply a drive signal having a predetermined waveform to the capacitive load. And acquiring the diagnostic voltage signal from a switch element different from the switch element to which the diagnostic voltage signal is applied, and detecting the voltage waveform.

  The present invention also relates to a droplet ejection head that ejects droplets by driving a capacitive load, and a recording medium for transporting a recording medium on which predetermined information is recorded by droplets ejected from the droplet ejection head. A liquid ejection device having a medium conveying means, a plurality of switch elements for applying a drive signal having a predetermined waveform to the capacitive load, and a diagnostic voltage from one of the switch elements to the capacitive load. A diagnostic voltage signal supply means for applying a signal; a voltage waveform detection means for acquiring the diagnostic voltage signal from a switch element different from the switch element to which the diagnostic voltage signal is applied; and detecting the voltage waveform; And a conduction control means for bringing two switch elements into a conduction state at the same time.

  Here, a plurality of capacitive loads are provided, and the conduction control means sets all the switch elements for applying a diagnostic voltage signal to each capacitive load in a conductive state, and outputs the diagnostic voltage signal. The switch element for obtaining may be individually in a conductive state for each capacitive load.

  A plurality of the capacitive loads are provided, and the conduction control means is configured to apply the diagnostic voltage signal to the capacitive loads and the switch for obtaining the diagnostic voltage signal. The element may be individually connected to each capacitive load.

  Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.

  1 is a schematic sectional view of a droplet discharge head used in the droplet discharge apparatus according to the present invention, FIG. 2 is a schematic plan view of the droplet discharge head, and FIG. A schematic plan view for explaining the relationship between a recording medium and a droplet discharge head in the apparatus is shown.

  In FIG. 1, a droplet discharge head 10 includes a nozzle plate 14 in which a plurality of nozzles (orifices) 12 are formed, and a pressure generation chamber that is provided corresponding to each nozzle 12 and is filled with ink 16 that is discharged from the nozzles 12. 18, an ink supply path 20 for supplying ink 16 from an ink tank (not shown) to the pressure generation chamber 18, and an actuator 22 provided corresponding to each pressure generation chamber 18.

  In the droplet discharge head 10, the pressure generation chamber 18 expands or contracts by driving the actuator 22, and the ink filled therein is discharged as a droplet from the nozzle 12 by this volume change. The actuator 22 is configured by a capacitive load such as a piezo element.

  In the present embodiment, as shown in FIG. 2, a configuration in which four nozzles 24a, 24b, 24c, and 24d are provided at equal intervals in the sub-scanning direction (Y-axis direction) of the droplet discharge head 10 will be described. The number of nozzles 12 is not limited to four, and may be three or less or five or more, and the pitch of nozzles 24a, 24b, 24c, and 24d is not limited to the above, and an arbitrary pitch is selected. Is possible.

  As shown in FIG. 3, the droplet discharge head 10 moves in the main scanning direction (X-axis direction) along a guide 26 provided in the main body of a droplet discharge device (not shown) and a recording medium (recording) Printing is performed by forming a large number of dots on the recording medium 28 while feeding the paper 28 in the sub-scanning direction (Y-axis direction) orthogonal to the feeding roller 30. In this case, the nozzle 12 passes through an arbitrary pixel position on the recording medium 28 only once.

  The recording medium 28 may be fixed and the droplet discharge head 10 may be moved, or the droplet discharge head 10 may be fixed and the recording medium 28 may be moved. The recording medium 28 may be arranged horizontally, but the arrangement posture of the recording medium 28 is not particularly limited as long as the droplet discharge head 10 can be relatively scanned along the surface of the recording medium 28. Absent.

  Further, the ejection of ink droplets from the nozzles 24a, 24b, 24c, and 24d may be performed only when the droplet ejection head 10 moves from the initial position from the left side to the right side in FIG. You may comprise also when moving from the said initial position to the left side of the right side of FIG. This has the advantage that gradation recording can be performed at a higher speed.

  The capacitive load such as the piezoelectric element constituting the actuator 22 of the droplet discharge head 10 described above is driven and controlled by the capacitive load driving device. Further, the capacitive load drive device includes a capacitive load drive diagnosis device that performs drive diagnosis of the capacitive load.

  FIG. 4 shows a block diagram of a configuration example of a capacitive load drive device including the capacitive load drive diagnostic device according to the present invention. In FIG. 4, the droplet discharge head 10 configured to include a plurality of capacitive loads such as piezo elements is driven by a drive waveform supplied from a drive control unit 34 formed on a semiconductor substrate. Further, the drive waveform of the droplet discharge head 10 and the diagnostic voltage signal for operation diagnosis are switched and applied to the drive control unit 34 by the switching unit 36. The drive waveform is supplied from the waveform generation means 38, and the diagnostic voltage signal is supplied from the diagnosis means 40. In this example, three types of driving waveforms are supplied from the waveform generating means 38. In addition, it is good also as a structure which uses one of the said 3 types of drive waveforms which the waveform generation means 38 produced | generated as a diagnostic voltage signal.

  The operation of the drive control unit 34 and the switching unit 36 is controlled by the control unit 42. The control unit 42 includes a CPU (central processing unit), and outputs a drive waveform selection signal and a mode switching signal to the drive control unit 34 and a mode switching signal to the switching unit 36. The drive waveform selection signal is supplied to the drive control unit 34 by the number (n) of capacitive loads included in the droplet discharge head 10 with 2-bit serial data. Since the four states can be represented by the 2-bit serial data, it is possible to instruct the selection of three types of waveforms in addition to the “waveform not selected” state.

  The drive control unit 34 includes a shift register 44, a latch 46, a decoder 48, a mode switching unit 50, a level shifter 52, and a parallel switch 54, and is configured on a semiconductor substrate.

  The shift register 44 receives the drive waveform selection signal (2 bits × n) received from the control unit 42, converts it into parallel, and outputs it to the latch 46. In the latch 46, the acquired drive waveform selection signal is output to the decoder 48, and is decoded by the decoder 48 to be one of the three types of waveform selection instruction signals. Note that there are three connections from the decoder 48 to the level shifter 52, which is the next stage, and the selection instruction signal in the “no waveform selection” state is cut off by hardware.

  Further, the mode switching unit 50 receives a mode switching signal from the control unit 42 and switches between the driving mode and the diagnostic mode of the droplet discharge head 10. This switching is performed by switching between a selection instruction signal and a mode switching signal input to the parallel switch 54 via the level shifter 52.

  The level shifter 52 converts the selection instruction signal output from the decoder 48 to a voltage level at which the parallel switch 54 can be driven. Further, the parallel switch 54 is a switch for conducting the drive waveform from the switching unit 36 to each capacitive load of the droplet discharge head 10, and one switch is provided for each of the three types of drive waveforms. . The parallel switch 54 selectively conducts any one of three types of drive waveforms to the capacitive load based on the selection instruction signal.

  FIG. 5 shows a configuration example of a capacitive load driving device around one capacitive load constituting the droplet discharge head 10. In FIG. 5, the selection control unit 56 includes the shift register 44, the latch 46, and the decoder 48 shown in FIG. 4, and one of the parallel switches 54a, 54b, and 54c via the three level shifters 52a, 52b, and 52c. A selection instruction signal is input to. When the selection instruction signal is input, the parallel switches 54 a, 54 b, 54 c conduct between the switching unit 36 and the capacitive load 32, and drive waveforms or diagnostic voltage signals from the switching unit 36 to the capacitive load 32. Apply. The capacitive load 32 corresponds to the actuator 22 shown in FIG.

  As described above, the switching unit 36 applies the drive waveform or the diagnostic voltage signal to the capacitive load 32 while switching. The switching unit 36 is configured to apply three drive waveforms from the common electrode A, the common electrode B, and the common electrode C to the capacitive loads 32 in the droplet discharge head 10, respectively. Here, the common electrode A is connected to the parallel switch 54a, the common electrode B is connected to the parallel switch 54b, and the common electrode C is connected to the parallel switch 54c. A diagnostic voltage signal is also applied to the capacitive load 32 from any one of the common electrode A, the common electrode B, and the common electrode C via the parallel switches 54a, 54b, and 54c. The switching means 36 determines from which of the common electrode A, the common electrode B, and the common electrode C the diagnostic voltage signal is applied. The switching means 36 in this case corresponds to the diagnostic voltage signal supply means of the present invention.

  In the present embodiment, the mode switching unit 50 is connected to the level shifter 52c. The mode switching unit 50 is configured by, for example, a two-input OR circuit (OR circuit), and outputs a mode switching signal to the level shifter 52c when receiving a mode switching signal from the control unit 42 of FIG. 4 in the diagnosis mode. . This mode switching signal is voltage-converted by the level shifter 52c, and the parallel switch 54c is always in a conductive state. In this case, since the mode switching signal is also supplied to the mode switching unit 50 connected to the other capacitive load 32, the parallel switch 54c becomes conductive for all the capacitive loads 32.

  On the other hand, a voltage signal for diagnosis is output from the waveform generation unit 38 or the diagnosis unit 40 to the common electrode C through the switching unit 36 under the control of the control unit 42, and the capacitor is connected through the parallel switch 54c in a conductive state. Applied to the sexual load 32.

  The diagnosis means 40 is applied to the capacitive load 32 from the parallel switch 54c via a parallel switch 54a or 54b different from the parallel switch 54c to which the switching means 36 applies a diagnostic voltage signal to the capacitive load 32. Obtain a diagnostic voltage signal. Accordingly, in the diagnostic mode, two of the parallel switches 54a, 54b, 54c are in a conductive state at the same time. In this case, the selection control unit 56 controls the conduction state of the parallel switch 54a or 54b. The parallel switch 54a or 54b is conduction-controlled for each capacitive load 32. In this case, the mode switching unit 50 and the selection control unit 56 correspond to the conduction control means of the present invention.

  The diagnostic means 40 has a function as a voltmeter for measuring the acquired diagnostic voltage signal waveform. In this case, the voltmeter has a high internal resistance, and is configured so that no current flows through the diagnostic means 40. In this way, the application of the diagnostic voltage signal to the capacitive load 32 and the acquisition of the diagnostic voltage signal by the diagnostic means 40 are performed using different common electrodes of the switching means 36 and are used for diagnostic purposes. Since no current flows through the diagnostic means 40 when the voltage signal is acquired, the diagnostic voltage signal can be measured without being distorted by resistance components such as the parallel switches 54a, 54b, 54c and wiring. Thereby, the measurement accuracy of the diagnostic voltage signal waveform applied to the capacitive load 32 can be improved. The diagnosis means 40 in this case corresponds to the voltage waveform detection means of the present invention.

  FIG. 6 shows an example of the conduction state of the parallel switches 54a, 54b, 54c in the diagnostic mode. In FIG. 6, parallel switches 54c-1 and 54a-1 are turned on in the capacitive load 32-1, and parallel switches 54c-2 and 54b-2 are turned on in the capacitive load 32-2. Here, the diagnostic voltage signal is applied from the common electrode C to the capacitive loads 32-1, 32-2, and 32-3 via the parallel switches 54c-1, 54c-2, and 54c-3. The diagnostic voltage signal applied to the capacitive load 32-1 is acquired by the diagnostic means 40 via the parallel switch 54a-1, and the diagnostic voltage signal applied to the capacitive load 32-2 is acquired from the parallel switch 54b. -2 is used to obtain and diagnose. In the example of FIG. 6, the diagnostic means 40 has not acquired the diagnostic voltage signal applied to the capacitive load 32-3, but at a later timing via the parallel switch 54a-3 or 54b-3. get. Diagnosis is performed in the same manner for other capacitive loads not shown in FIG.

  Thus, for each capacitive load, the conduction control of the parallel switches 54a, 54b, 54c is performed by the selection control unit 56, and the switching of the common electrodes A, B, C to which the diagnosis unit 40 is connected is performed by the switching unit 36. Therefore, even if the number of capacitive loads increases, measurement for each capacitive load can be easily performed.

  FIG. 7 shows another configuration example of the capacitive load driving device around the capacitive load. A characteristic point in FIG. 7 is that mode switching units 50a, 50b, and 50c are provided in front of all level shifters 52a, 52b, and 52c. With such a configuration, a parallel switch for applying a diagnostic voltage signal from the switching unit 36 to the capacitive load 32 can be freely selected from the parallel switches 54a, 54b, and 54c. Thereby, for example, even when there is a fault in the parallel switches 54a, 54b, 54c, the diagnostic operation can be executed flexibly.

  A mode switching signal is input from the decoder 58 to the mode switching units 50a, 50b, and 50c. The mode switching signal is selectively input to any one of the mode switching units 50a, 50b, and 50c by the decoder 58. The mode switching units 50a, 50b, and 50c can be selected by inputting 2-bit mode switching code data to the decoder 58, for example. That is, since the four states can be designated by the 2-bit mode switching code data in the same manner as the drive waveform selection signal described in FIG. 4, three of these states (for example, 01, 10, 32) are designated as the mode switching unit 50a. , 50b, 50c, and a mode switching signal is output to the corresponding mode switching units 50a, 50b, 50c when one of the three mode switching code data is input to the decoder 58.

  FIG. 8 shows still another configuration example of the capacitive load driving device around the capacitive load. A characteristic point in FIG. 8 is that the output of the decoder 58 described in FIG. 7 and the output of the shift register 60 are input to AND circuits (logical product circuits) 62a, 62b, 62c, and the AND circuits 62a, 62b, The output of 62c is input to each mode switching unit 50a, 50b, 50c, respectively.

  The shift register 60 has the same number of bits as the number (n) of the capacitive loads 32 included in the droplet discharge head 10, only the first bit is 1 (H), and the other bits are all 0 (L ) Scan data and scan clock are input. The shift register 60 outputs n bits in parallel, and each output bit is input to the AND circuits 62a, 62b, 62c provided for each capacitive load 32 one bit at a time. In the shift register 60, since the H bit is transferred for each scanning clock, the H bit is sequentially input to the AND circuits 62a, 62b, 62c provided for each capacitive load 32. Of the AND circuits 62a, 62b, and 62c of the capacitive load 32 to which the H bit is input, the mode switching signal is input to the corresponding mode switching units 50a, 50b, and 50c from the mode switching signal input from the decoder 58. Is entered.

  With the above configuration, the parallel switch designated by the decoder 58 is turned on for a specific one of the capacitive loads 32. For this reason, a diagnostic operation can be performed for each capacitive load 32 individually.

  Instead of providing the mode switching units 50a, 50b, 50c, the decoder 58, the shift register 60, and the AND circuits 62a, 62b, 62c, a mode switching signal is sent from the selection control unit 56 to the level shifters 52a, 52b, 52c in the diagnosis mode. It may be configured such that any one of the parallel switches 54a, 54b, 54c is turned on. In this case, 3-bit (3 bits × n) serial data is input to the shift register 44 shown in FIG. As a result, eight states can be specified. Of these, six states are used, and three drive modes and three diagnostic modes can be specified. Even with such a configuration, a diagnostic operation can be performed for each capacitive load 32 individually.

  FIG. 9 shows a truth table when 3-bit serial data is used. In FIG. 9, the most significant bit of the input signal is a mode selection bit, and the other two bits are waveform selection bits. That is, when the mode selection bit is L, the drive mode is selected, and any one of the parallel switches 54a, 54b, and 54c is selected according to the waveform selection bit and becomes conductive. On the other hand, when the mode selection bit is H, the diagnosis mode is selected, and any two of the parallel switches 54a, 54b, and 54c are selected according to the waveform selection bit and become conductive. A diagnostic voltage signal is applied to the capacitive load 32 via one of the two selected parallel switches, and the diagnostic means 40 obtains the diagnostic voltage signal from the other.

  The parallel switch 54 as the switching element, the switching unit 36 as the diagnostic voltage signal supply unit, the diagnostic unit 40 as the voltage waveform detection unit, the mode switching unit 50 and the selection control unit 56 as the conduction control unit, etc. The constituent elements may be provided outside the droplet discharge head 10 or may be provided inside the droplet discharge head 10.

  In the above-described embodiment, an example in which a piezoelectric element is used as a capacitive element has been described. However, the present invention is not limited to this, and instead of the piezoelectric element, for example, one of the counter electrodes is used as an elastic electrode. The same effect can be obtained by using an electrostatic actuator that utilizes displacement of the elastic electrode due to electrostatic force, liquid crystal, or the like.

It is a schematic sectional drawing of the droplet discharge head used for the droplet discharge apparatus concerning this invention. FIG. 3 is a schematic plan view of a droplet discharge head used in the droplet discharge apparatus according to the present invention. FIG. 4 is a schematic plan view for explaining the relationship between a recording medium and a droplet discharge head in the droplet discharge apparatus according to the present invention. It is a block diagram of the structural example of the capacitive load drive device containing the capacitive load drive diagnostic apparatus concerning this invention. It is a figure which shows the structural example of the capacitive load drive device around capacitive load. It is a figure which shows the example of the conduction | electrical_connection state of the parallel switch in diagnostic mode. It is a figure which shows the other structural example of the capacitive load drive device around capacitive load. It is a figure which shows the further another structural example of the capacitive load drive device around capacitive load. It is a figure which shows the truth table at the time of using 3-bit serial data.

Explanation of symbols

  10 droplet ejection head, 12 nozzles, 14 nozzle plates, 16 ink, 18 pressure generation chamber, 20 ink supply path, 22 actuator, 24a, 24b, 24c, 24d nozzle, 26 guide, 28 recording medium, 30 feed roller, 32 Capacitive load, 34 Drive control unit, 36 switching unit, 38 waveform generating unit, 40 diagnostic unit, 42 control unit, 44, 60 shift register, 46 latch, 48, 58 decoder, 50 mode switching unit, 52 level shifter, 54 parallel Switch, 56 selection control unit.

Claims (8)

A plurality of switch elements for applying a drive signal having a predetermined waveform to the capacitive load;
A diagnostic voltage signal supply means for applying a diagnostic voltage signal from one of the switch elements to the capacitive load;
Voltage waveform detection means for acquiring the diagnostic voltage signal from a switch element different from the switch element to which the diagnostic voltage signal is applied, and detecting the voltage waveform;
Conduction control means for simultaneously bringing the two switch elements into conduction;
A capacitive load drive diagnostic apparatus comprising:   2. The capacitive load drive diagnostic apparatus according to claim 1, wherein a plurality of the capacitive loads are provided, and the conduction control means includes all the switching elements for applying a diagnostic voltage signal to each of the capacitive loads. The capacitive load drive diagnostic apparatus, wherein the switch element for making a conductive state and acquiring the diagnostic voltage signal is individually made conductive for each capacitive load.   2. The capacitive load drive diagnostic apparatus according to claim 1, wherein a plurality of the capacitive loads are provided, and the conduction control means includes the switch element for applying a diagnostic voltage signal to the capacitive loads, A capacitive load drive diagnostic apparatus, wherein the switch element for acquiring a diagnostic voltage signal is individually rendered conductive for each capacitive load.   4. The capacitive load drive diagnostic device according to claim 1, wherein the capacitive load drive diagnostic device diagnoses the drive of the capacitive load used in the droplet discharge device. Applying a diagnostic voltage signal to the capacitive load from one of a plurality of switch elements for applying a drive signal of a predetermined waveform to the capacitive load;
Obtaining the diagnostic voltage signal from a switch element different from the switch element to which the diagnostic voltage signal is applied, and detecting the voltage waveform;
A capacitive load drive diagnostic method comprising: A droplet discharge head for discharging droplets by driving a capacitive load;
A recording medium conveying means for conveying a recording medium on which predetermined information is recorded by droplets ejected from the droplet ejection head,
A plurality of switch elements for applying a drive signal having a predetermined waveform to the capacitive load;
A diagnostic voltage signal supply means for applying a diagnostic voltage signal from one of the switch elements to the capacitive load;
Voltage waveform detection means for acquiring the diagnostic voltage signal from a switch element different from the switch element to which the diagnostic voltage signal is applied, and detecting the voltage waveform;
Conduction control means for simultaneously bringing the two switch elements into conduction;
A droplet discharge apparatus comprising:   7. The liquid droplet ejection apparatus according to claim 6, wherein a plurality of the capacitive loads are provided, and the conduction control means conducts all of the switch elements for applying a diagnostic voltage signal to each of the capacitive loads. And the switch element for acquiring the diagnostic voltage signal is individually turned on for each capacitive load. 7. The liquid droplet ejection apparatus according to claim 6, wherein a plurality of the capacitive loads are provided, and the conduction control means includes the switch element for applying a diagnostic voltage signal to each of the capacitive loads and the diagnostic load. A droplet discharge device, wherein the switch element for acquiring a voltage signal is individually brought into a conductive state for each capacitive load.

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