JP7145017B2 - LIQUID JET HEAD, LIQUID JET RECORDING APPARATUS AND DRIVING SIGNAL GENERATING SYSTEM - Google Patents

Description

The present disclosure relates to a liquid jet head, a liquid jet recording apparatus, and a drive signal generation system.

2. Description of the Related Art A liquid jet recording apparatus having a liquid jet head is used in various fields, and various types of liquid jet heads have been developed (for example, see Patent Document 1).

JP 2014-151646 A

Such a liquid jet head is required to improve user convenience. It is desirable to provide a liquid jet head, a liquid jet recording apparatus, and a drive signal generation system that can improve user convenience.

A liquid ejecting head according to an embodiment of the present disclosure includes an ejecting section having a plurality of nozzles for ejecting liquid; An acoustic measurement unit having a driving unit for ejecting a liquid, a transmitter for transmitting an ultrasonic acoustic signal into the liquid, and a receiver for receiving the ultrasonic acoustic signal from the liquid, and the acoustic measurement and a signal generator for generating the drive signal based on a comparison of signals at the transmitter and receiver at the unit . This signal generator calculates the speed of sound in the liquid based on the arrival time in the liquid from the transmitter to the receiver of the acoustic signal of the ultrasonic wave, and based on the obtained speed of sound in the liquid, generates a pulse Find the pulse width in, find the attenuation in the liquid from the transmitter to the receiver in the acoustic signal of the ultrasonic wave, and based on the found attenuation, find the peak value of the pulse, find the pulse width and wave A pulse with a high value is used to generate the drive signal.

A liquid jet recording apparatus according to an embodiment of the present disclosure includes the liquid jet head according to the embodiment of the present disclosure.

A drive signal generation system according to an embodiment of the present disclosure is a system for generating a drive signal having one or more pulses to be applied to an ejection unit having a plurality of nozzles for ejecting liquid, An acoustic measurement unit having a transmitter that transmits an ultrasonic acoustic signal into the liquid and a receiver that receives the ultrasonic acoustic signal from the liquid, and the transmitter and the receiver in the acoustic measurement unit and a signal generator for generating the drive signal based on the comparison of the signals . This signal generator calculates the speed of sound in the liquid based on the arrival time in the liquid from the transmitter to the receiver of the acoustic signal of the ultrasonic wave, and based on the obtained speed of sound in the liquid, generates a pulse Find the pulse width in, find the attenuation in the liquid from the transmitter to the receiver in the acoustic signal of the ultrasonic wave, and based on the found attenuation, find the peak value of the pulse, find the pulse width and wave A pulse with a high value is used to generate the drive signal.

According to the liquid jet head, the liquid jet recording apparatus, and the drive signal generation system according to the embodiment of the present disclosure, it is possible to improve user convenience.

1 is a schematic perspective view showing a schematic configuration example of a liquid jet recording apparatus according to an embodiment of the present disclosure; FIG. 2 is a schematic diagram showing a schematic configuration example of the liquid jet head shown in FIG. 1; FIG. 3 is a block diagram showing a detailed configuration example of the liquid jet head shown in FIG. 2; FIG. FIG. 3 is a timing diagram schematically showing a configuration example of a drive signal; 4 is a block diagram showing a detailed configuration example and the like of a signal generator shown in FIG. 3; FIG. 6 is a block diagram showing a detailed configuration example of an analytic signal generator shown in FIG. 5; FIG. 1 is a block diagram showing a schematic configuration example of a liquid jet recording apparatus according to a comparative example; FIG. 4 is a flow chart showing drive signal generation processing and the like according to the embodiment. FIG. 9 is a timing chart showing examples of waveforms of various signals during the drive signal generation process shown in FIG. 8 ; FIG. 4 is a schematic diagram for explaining an outline of a pulse width setting method and the like; 3 is a block diagram showing a schematic configuration example of a liquid jet recording apparatus according to Modification 1. FIG. 10 is a block diagram showing a schematic configuration example of a liquid jet recording apparatus according to Modification 2; FIG.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The description will be given in the following order.
1. Embodiment (example in which an acoustic measurement unit and a signal generation unit are provided in a liquid jet head)
2. Modifications Modification 1 (example in which part of the acoustic measurement unit is provided inside the injection unit)
Modification 2 (example in which an acoustic measurement unit and a signal generation unit are provided outside the liquid jet head)
3. Other variations

<1. Embodiment>
[A. Overall Configuration of Printer 1]
FIG. 1 is a schematic perspective view of a schematic configuration example of a printer 1 as a liquid jet recording apparatus according to an embodiment of the present disclosure. The printer 1 is an inkjet printer that uses ink 9, which will be described later, to record (print) images, characters, and the like on recording paper P as a recording medium.

The printer 1 includes a pair of transport mechanisms 2a and 2b, an ink tank 3, an inkjet head 4, an ink supply pipe 50, and a scanning mechanism 6, as shown in FIG. Each of these members is housed in a housing 10 having a predetermined shape. In addition, in each drawing used for the description of this specification, the scale of each member is appropriately changed so that each member has a recognizable size.

Here, the printer 1 corresponds to a specific example of a "liquid jet recording apparatus" in the present disclosure, and the inkjet heads 4 (inkjet heads 4Y, 4M, 4C, 4K to be described later) are "liquid jet heads" in the present disclosure. corresponds to a specific example of Also, the ink 9 corresponds to a specific example of "liquid" in the present disclosure.

Each of the transport mechanisms 2a and 2b is a mechanism for transporting the recording paper P along the transport direction d (X-axis direction), as shown in FIG. Each of these transport mechanisms 2a and 2b has a grid roller 21, a pinch roller 22 and a drive mechanism (not shown). This driving mechanism is a mechanism for rotating the grid roller 21 around its axis (rotating within the ZX plane), and is composed of, for example, a motor.

(ink tank 3)
The ink tank 3 is a tank that contains ink 9 therein. In this example, as shown in FIG. 1, the ink tank 3 contains four inks 9 of yellow (Y), magenta (M), cyan (C), and black (K). There are different types of tanks. That is, an ink tank 3Y containing yellow ink 9, an ink tank 3M containing magenta ink 9, an ink tank 3C containing cyan ink 9, and an ink tank 3K containing black ink 9 are provided. is provided. These ink tanks 3Y, 3M, 3C, and 3K are arranged side by side along the X-axis direction within the housing 10. As shown in FIG.

Note that the ink tanks 3Y, 3M, 3C, and 3K have the same configuration except for the color of the ink 9 contained therein, so that they will be collectively referred to as the ink tank 3 below.

(inkjet head 4)
The inkjet head 4 is a head that ejects droplets of ink 9 onto the recording paper P from a plurality of nozzles (nozzle holes Hn), which will be described later, to record (print) images, characters, and the like. . As the ink jet head 4, as shown in FIG. 1 in this example, there are four types of heads that individually eject the four color inks 9 contained in the ink tanks 3Y, 3M, 3C, and 3K. is provided. That is, an inkjet head 4Y that ejects yellow ink 9, an inkjet head 4M that ejects magenta ink 9, an inkjet head 4C that ejects cyan ink 9, and an inkjet head 4K that ejects black ink 9 are provided. is provided. These inkjet heads 4Y, 4M, 4C, and 4K are arranged side by side along the Y-axis direction within the housing 10 .

Since the inkjet heads 4Y, 4M, 4C, and 4K have the same configuration except for the color of the ink 9 to be used, they will be collectively referred to as the inkjet head 4 below. A detailed configuration example of the inkjet head 4 will be described later (FIGS. 2 to 6).

The ink supply pipe 50 is a pipe through which the ink 9 is supplied from the ink tank 3 toward the inkjet head 4 . The ink supply pipe 50 is composed of, for example, a flexible hose that is flexible enough to follow the operation of the scanning mechanism 6 described below.

(scanning mechanism 6)
The scanning mechanism 6 is a mechanism for scanning the inkjet head 4 along the width direction of the recording paper P (Y-axis direction). As shown in FIG. 1, the scanning mechanism 6 includes a pair of guide rails 61a and 61b extending along the Y-axis direction, and a carriage 62 movably supported by these guide rails 61a and 61b. , and a driving mechanism 63 for moving the carriage 62 along the Y-axis direction.

The drive mechanism 63 includes a pair of pulleys 631a and 631b arranged between the guide rails 61a and 61b, an endless belt 632 wound between the pulleys 631a and 631b, and a drive motor 633 for rotating the pulley 631a. and have Also, on the carriage 62, the above-described four types of inkjet heads 4Y, 4M, 4C, and 4K are arranged side by side along the Y-axis direction.

The scanning mechanism 6 and the transport mechanisms 2a and 2b described above constitute a moving mechanism for moving the ink jet head 4 and the recording paper P relative to each other.

[B. Detailed configuration of inkjet head 4]
Next, a detailed configuration example of the inkjet head 4 will be described with reference to FIGS. 2 to 6. FIG.

Here, FIG. 2 schematically shows a schematic configuration example of the inkjet head 4 . FIG. 3 is a block diagram showing a detailed configuration example of the inkjet head 4 shown in FIG.

The inkjet head 4 has a nozzle plate 41, an actuator plate 42, a temperature detection section 45, a sound measurement section 47, a signal generation section 48 and a drive section 49, as shown in FIGS.

Note that the nozzle plate 41 and the actuator plate 42 correspond to a specific example of the "injection section" in the present disclosure. Also, the signal generation unit 48 corresponds to a specific example of the "driving signal generation system" in the present disclosure.

(Nozzle plate 41)
The nozzle plate 41 is a plate made of a film material such as polyimide or a metal material, and has a plurality of nozzle holes Hn for ejecting the ink 9 as shown in FIGS. , see the dashed arrows in FIG. 3). These nozzle holes Hn are arranged in a straight line (along the X-axis direction in this example) at predetermined intervals. Each nozzle hole Hn corresponds to a specific example of "nozzle" in the present disclosure.

(Actuator plate 42)
The actuator plate 42 is a plate made of a piezoelectric material such as PZT (lead zirconate titanate). This actuator plate 42 is provided with a plurality of channels (not shown). These channels are portions that function as pressure chambers for applying pressure to the ink 9, and are arranged side by side so as to be parallel to each other at predetermined intervals. Each channel is defined by a drive wall (not shown) made of a piezoelectric material, and forms a recessed groove when viewed in cross section.

Such channels include ejection channels for ejecting the ink 9 (ejection channels Ce described later; see FIG. 10) and dummy channels (non-ejection channels) for not ejecting the ink 9 . In other words, the ejection channels are filled with the ink 9 while the dummy channels are not filled with the ink 9 . Each ejection channel communicates with the nozzle hole Hn in the nozzle plate 41, while each dummy channel does not communicate with the nozzle hole Hn. These ejection channels and dummy channels are alternately arranged along a predetermined direction.

A drive electrode (not shown) is provided on each of the opposing inner surfaces of the drive wall. The drive electrodes include a common electrode (common electrode) provided on the inner surface facing the ejection channel, and an active electrode (individual electrode) provided on the inner surface facing the dummy channel. These drive electrodes and a drive circuit on a drive substrate (not shown) are electrically connected via a plurality of extraction electrodes formed on a flexible substrate (not shown). As a result, a driving voltage Vd (driving signal Sd), which will be described later, is applied to each driving electrode from a driving circuit including a driving section 49, which will be described later, via the flexible substrate.

(Temperature detector 45)
The temperature detector 45 detects the temperature (actuator temperature Tpzt) near the actuator plate 42 in the inkjet head 4, as shown in FIG. The actuator temperature Tpzt detected by the temperature detector 45 in this manner is output to the signal generator 48, which will be described later.

(Sound measurement unit 47)
As shown in FIG. 3, the acoustic measurement unit 47 performs predetermined measurements (acoustic measurements) on the ink 9 flowing through the ink supply pipe 50 described above. 472.

The ultrasonic transmitter 471 is, as shown in FIG. 3, a device that transmits an ultrasonic acoustic signal Sac into the ink 9 as an acoustic signal Sacout. It should be noted that such transmission of the acoustic signal Sacout is performed using electro-mechanical conversion, for example, based on the electrical signal output from the signal generator 48 (see FIG. 3).

The ultrasonic receiver 472 is a device that receives the ultrasonic acoustic signal Sac from the ink 9, as shown in FIG. Specifically, the ultrasonic receiver 472 receives the acoustic signal Sac output from the ultrasonic transmitter 471 and traveling through the ink 9 as the acoustic signal Sacin. The acoustic signal Sacin is received by, for example, mechanical-electrical conversion, and the acoustic signal Sacin thus obtained is output to the signal generator 48. (See Fig. 3).

Incidentally, each of such acoustic signals Sac (Sacout, Sacin) is configured using a sine wave in the present embodiment, for example, as described later (see FIG. 9). By configuring the acoustic signal Sac using such a sine wave, the frequency component in the acoustic signal Sac becomes single. In comparison with the case where the acoustic signal Sac is constructed by That is, for example, separation processing of frequency components such as Fast Fourier Transform (FFT) becomes unnecessary, so that the analysis processing in the analytic signal generation unit 482 (described later) in the signal generation unit 48 is simplified. It is possible.

Here, such ultrasonic transmitter 471 and ultrasonic receiver 472 respectively correspond to specific examples of "transmitter" and "receiver" in the present disclosure.

(Signal generator 48)
Although details will be described later, the signal generator 48 generates one or more pulses (pulse width Wp, voltage value Vp) are set, and the set pulse is used to generate the drive signal Sd.

Here, FIGS. 4A to 4C are schematic timing diagrams of configuration examples of such a driving signal Sd. In FIGS. 4A to 4C, the horizontal axis indicates time t, and the vertical axis indicates drive voltage Vd (positive voltage in this example) in drive signal Sd.

First, the driving signal Sd shown in FIG. 4A has one pulse (pulse Pa), and is an example of so-called "1 drop". This pulse Pa is an ON period provided between the rising timing and the falling timing, and has a pulse width Wpa1 and a voltage value Vp1 as an example of the pulse width Wp and voltage value Vp described above.

On the other hand, the drive signal Sd shown in FIG. 4B has the following two pulses (pulses Pa, Pb) as pulses to which the so-called "multi-pulse method" is applied (so-called "two-drop" example). That is, two pulses Pa and Pb are provided as such pulses (ON period). An OFF period (“OFF1”) is provided between these two pulses Pa and Pb. As an example of the pulse width Wp and voltage value Vp described above, the pulse Pa has a pulse width Wpa2 and a voltage value Vp2, and the pulse Pb has a pulse width Wpb2 and a voltage value Vp2.

Similarly, the drive signal Sd shown in FIG. 4C has the following three pulses (pulses Pa, Pb, Pc) as pulses to which the above-described "multi-pulse method" is applied (so-called Example in the case of "3 drops"). That is, three pulses Pa, Pb, and Pc are provided as such pulses (ON period). An OFF period (“OFF1”) is provided between the pulses Pa and Pb, and an OFF period (“OFF2”) is provided between the pulses Pb and Pc. Further, as an example of the pulse width Wp and the voltage value Vp described above, the pulse Pa has a pulse width Wpa3 and a voltage value Vp3, the pulse Pb has a pulse width Wpb3 and a voltage value Vp3, and the pulse Pc has a pulse width Wpc3 and a voltage value Vp3. It has a voltage value Vp3.

Each of the pulses Pa, Pb, and Pc in these driving signals Sd is a positive pulse that expands the above-described ejection channel during the period of high state and contracts the ejection channel during the period of low state. It has become.

Here, although the details will be described later, the signal generation unit 48 obtains the pulse width Wp and the voltage value Vp of such pulses (pulses Pa, Pb, and Pc), and has the obtained pulse width Wp and voltage value Vp. A pulse is used to generate the drive signal Sd. The details of the process of generating the drive signal Sd by the signal generator 48 will be described later (FIGS. 8 to 10).

Here, the voltage value Vp described above corresponds to a specific example of the “peak value” in the present disclosure. Further, the above-described "pulse" is a conceptual concept including not only a rectangular wave as shown in FIG. 4, but also a trapezoidal wave, a triangular wave, a step wave, and the like.

(Driving unit 49)
The drive unit 49 applies the drive voltage Vd (drive signal Sd) to the actuator plate 42 to expand or contract the ejection channel, thereby ejecting the ink 9 from each nozzle hole Hn (ejection signal Sd). (see FIGS. 2 and 3). Specifically, the drive section 49 uses the drive signal Sd generated by the signal generation section 48 to perform such an injection operation.

[C. Detailed Configuration of Signal Generation Unit 48]
Next, a detailed configuration example of the signal generator 48 will be described with reference to FIGS. 5 and 6. FIG. FIG. 5 is a block diagram showing a detailed configuration example of the signal generation section 48 together with the sound measurement section 47 described above. FIG. 6 is a block diagram showing a detailed configuration example of the analytic signal generator 482 (described later) shown in FIG.

As shown in FIG. 5, the signal generator 48 includes a bandpass filter 481, an analytic signal generator 482, an amplitude signal generator 483, a counter circuit 484, an acoustic signal generator 485, an attenuation calculator 486, and a waveform setter. 487.

(Band pass filter 481)
The bandpass filter 481 performs predetermined bandpass filtering on the acoustic signal Sacin acquired from the ultrasonic receiver 472, as shown in FIG. This band-pass filtering process is a filtering process for suppressing noise in the acoustic signal Sacin, and the sine wave band used for measurement by the acoustic measurement unit 47, for example, is the passband. The acoustic signal Sacin after such band-pass filtering is output to the analytic signal generator 482 as the signal S0 (sine wave signal).

(analysis signal generator 482)
The analytic signal generator 482 performs a predetermined analysis process on the signal S0, thereby outputting two analytic signals S1a and S1b as shown in FIG. In this example, the analytic signal S1b is a signal whose phase is delayed by 90° with respect to the analytic signal S1b.

As shown in FIG. 6, the analytic signal generator 482 has a Hilbert transform circuit 482a and a delay circuit 482b.

The Hilbert transform circuit 482a is a circuit that performs a Hilbert transform on the input sine wave signal S0 and outputs an analytic signal S1b composed of a cosine wave.

The delay circuit 482b is a circuit that applies a predetermined delay process to the input sine wave signal S0 and outputs a sine wave analysis signal S1a. Specifically, the delay circuit 482b delays the signal S0 by the same amount of time as the time from when the signal S0 is input until when the analysis signal S1b is output. .

(Amplitude signal generator 483)
As shown in FIG. 5, the amplitude signal generator 483 performs predetermined arithmetic processing on the two analytic signals S1a and S1b to generate a signal indicating the value of the amplitude A2 in the acoustic signal Sacin. A circuit for outputting an instantaneous amplitude signal S2.

Here, the two analytic signals S1a and S1b are respectively a sine wave and a cosine wave, as described above. Therefore, the above-described amplitude A2 is obtained by using the following formula (1), which is a trigonometric function formula, and using the following formula (2).
(sin θ) ² + (cos θ) ² = 1 (1)
A2={(S1a) ² +(S1b) ² } ^1/2 (2)

(Counter circuit 484)
The counter circuit 484, as shown in FIG. 5, is a circuit that performs predetermined counter processing based on the instantaneous amplitude signal S2. Although the details will be described later (see FIG. 9), the timing of generation of the acoustic signal Sacout from the ultrasonic transmitter 471 and the timing of the peak value (amplitude A2) of the instantaneous amplitude signal S2 are determined by performing such counter processing. , and a time difference signal S3 indicating the time difference (arrival time Δt) between .

Specifically, first, as described above, when the acoustic signal Sac of the ultrasonic wave travels through the ink 9, the speed of the acoustic signal Sac, that is, the speed of the sound in the ink 9 Vs The arrival time Δt of the acoustic signal Sac from the sonic transmitter 471 to the ultrasonic receiver 472 changes. Further, the instantaneous amplitude signal S2 indicates "0" when the acoustic signal Sac is not received, and indicates a crest value (peak value) corresponding to the amplitude A2 when the acoustic signal Sac is received. It becomes a curve-shaped signal (see FIG. 9, which will be described later). Therefore, by measuring the time difference (arrival time Δt) between the timing of the peak value (amplitude A2) in this instantaneous amplitude signal S2 and the timing of generation of the acoustic signal Sacout by counter processing in the counter circuit 484, the above-described A time difference signal S3 is generated. The value of the time difference signal S3 changes according to the speed of sound Vs in the ink 9 described above.

(Acoustic signal generator 485)
As shown in FIG. 5, the acoustic signal generation unit 485 adjusts the acoustic wave period Tac of the acoustic signal Sacout transmitted from the ultrasonic wave transmitter 471 based on the time difference signal S3 described above, and then generates ultrasonic waves. It outputs to the device 471 . Specifically, the acoustic signal generator 485 adjusts the sound wave period Tac in the acoustic signal Sacout so that the value of the time difference signal S3 is always kept constant even if the sound velocity Vs in the ink 9 changes. It has become. The sound wave period Tac adjusted in this manner is output to the waveform setting section 487 as shown in FIG.

(Attenuation calculation unit 486)
As shown in FIG. 5, the attenuation computing unit 486 calculates the acoustic signal Sacout ( Attenuation At between the transmission signal) and the acoustic signal Sacin (reception signal) is calculated. Such amplitude attenuation between the acoustic signals Sacout and Sacin is caused by the viscous resistance of the ink 9 and the like, although the details will be described later. The attenuation At thus obtained is output to the waveform setting section 487 as shown in FIG.

Incidentally, such an attenuation At is defined using the difference or ratio between the amplitudes A1 and A2, as shown by the following equations (3) and (4), for example.
At=(A1-A2) ……(3)
At=(A2/A1) ……(4)

(Waveform setting unit 487)
As shown in FIG. 5, the waveform setting unit 487 generates a predetermined waveform in the drive signal Sd based on the sound wave cycle Tac output from the acoustic signal generation unit 485 and the attenuation At output from the attenuation calculation unit 486. It sets the waveform. Specifically, the waveform setting unit 487 sets the pulse width Wp and the voltage value Vp of the pulses (the aforementioned pulses Pa, Pb, Pc, etc.) in the driving signal Sd based on the sound wave cycle Tac and the attenuation At. It is designed to be set. Details of the process of generating the drive signal Sd, including such waveform setting process, will be described later (FIGS. 8 to 10).

[Operation and action/effect]
(A. Basic operation of printer 1)
In the printer 1, a recording operation (printing operation) of images, characters, etc. on the recording paper P is performed in the following manner. In the initial state, it is assumed that the four types of ink tanks 3 (3Y, 3M, 3C, and 3K) shown in FIG. . Further, the ink 9 in the ink tank 3 is in a state of filling the ink jet head 4 through the ink supply pipe 50 .

When the printer 1 is operated in such an initial state, the grid rollers 21 in the transport mechanisms 2a and 2b rotate, so that the recording paper P is placed between the grid rollers 21 and the pinch rollers 22 in the transport direction d (X axial direction). Simultaneously with such a conveying operation, the drive motor 633 in the drive mechanism 63 rotates the pulleys 631a and 631b, respectively, thereby operating the endless belt 632. As shown in FIG. As a result, the carriage 62 reciprocates along the width direction of the recording paper P (Y-axis direction) while being guided by the guide rails 61a and 61b. At this time, the inkjet heads 4 (4Y, 4M, 4C, and 4K) appropriately eject four colors of ink 9 onto the recording paper P, thereby recording images, characters, and the like on the recording paper P. be.

(B. Detailed operation in inkjet head 4)
Next, a detailed operation (ejection operation of the ink 9) in the inkjet head 4 will be described. That is, in this inkjet head 4, the ejection operation of the ink 9 using the shear mode is performed as follows.

First, the driving section 49 applies a driving voltage Vd (driving signal Sd) to the aforementioned driving electrodes (common electrode and active electrode) in the actuator plate 42 (see FIGS. 2 and 3). Specifically, the driving section 49 applies the driving voltage Vd to each of the driving electrodes arranged on the pair of driving walls that define the aforementioned ejection channel. As a result, the pair of drive walls are deformed so as to protrude toward the dummy channel adjacent to the ejection channel.

At this time, the driving wall bends and deforms in a V shape centering on the intermediate position in the depth direction of the driving wall. Due to such bending deformation of the driving wall, the ejection channel is deformed as if it were expanding. In this way, the volume of the ejection channel increases due to bending deformation due to the piezoelectric thickness slip effect in the pair of drive walls. As the volume of the ejection channel increases, the ink 9 is guided into the ejection channel.

Next, the ink 9 guided into the ejection channel in this manner becomes a pressure wave and propagates inside the ejection channel. Then, the driving voltage Vd applied to the driving electrode becomes 0 (zero) V at the timing when the pressure wave reaches the nozzle hole Hn of the nozzle plate 41 (or the timing in the vicinity thereof). As a result, the driving wall is restored from the bending deformation state described above, and as a result, the once increased volume of the discharge channel returns to its original volume.

In this manner, the pressure inside the ejection channel increases and the ink 9 inside the ejection channel is pressurized in the process of restoring the volume of the ejection channel. As a result, ink droplets 9 are ejected to the outside (toward the recording paper P) through the nozzle holes Hn (see FIGS. 2 and 3). In this manner, the ink 9 is ejected from the inkjet head 4, and as a result, an image, characters, or the like is recorded on the recording paper P (printing operation).

(C. Operation for generating drive signal Sd)
Next, with reference to FIGS. 7 to 10 in addition to FIGS. 1 to 6, the operation (generation processing) of the driving signal Sd by the signal generation unit 48 described above will be described in detail while comparing with a comparative example. do.

(C-1. Comparative example)
FIG. 7 is a block diagram showing a schematic configuration example of a printer 101 as a liquid jet recording apparatus according to a comparative example. A printer 101 of this comparative example includes an inkjet head 104 as a liquid jet head according to the comparative example. Further, the inkjet head 104 of this comparative example includes a drive section 109 having a waveform information storage section 108 as well as the nozzle plate 41, the actuator plate 42 and the temperature detection section 45 described above. That is, the inkjet head 104 does not include (omit) the acoustic measuring unit 47 and the signal generating unit 48 in the inkjet head 4 (see FIG. 3) of this embodiment, and instead of the driving unit 49 is provided with a drive unit 109.

The waveform information storage unit 108 in the drive unit 109 stores waveform information (for example, the aforementioned pulse width Wp, voltage value Vp, etc.) for setting the pulses in the drive signal Sd (see pulses Pa to Pc in FIG. 4). information) is stored in advance. Such waveform information is, for example, information calculated by manually observing ejection of the ink 9 from each nozzle hole Hn in the nozzle plate 41 in advance. The drive unit 109 sets the drive signal Sd using the waveform information stored in advance in the waveform information storage unit 108 based on the print data and the like input from the main body of the printer 101, and the drive signal Sd is applied to the actuator. It is adapted to be applied to plate 42 .

By the way, in an inkjet head, it is generally known that the optimal pressure generation timing (an on-pulse peak, which will be described later) and the pressure setting conditions (driving voltage) largely differ depending on the shape of the ejection channel described above, the physical properties of the ink 9, and the like. It is Therefore, in order to optimize such pressure generation timing and pressure setting conditions, in this comparative example, it is necessary to manually observe the ejection (flying observation) of the ink 9 as described above in advance. be. However, since the waveform information using the observation of the jetting of the ink 9 is created in advance by repeating trial and error, it requires an enormous amount of time and sufficient experience and knowledge. Or, it may be necessary to create the above-described waveform information for each type of ink 9 .

In addition, printer users (end users, etc.) desire to freely change the ink 9, but in the printer 101 of this comparative example, if the ink 9 is changed, the waveform information described above cannot be appropriately used. It will be gone. In other words, the pressure generation timing and the pressure setting conditions cannot be optimized, and there is a risk that the print quality will deteriorate. Therefore, considering the risk of deterioration in print quality, it can be said that the user of the printer 101 actually has very little freedom in selecting the ink 9 .

As described above, in this comparative example, it is necessary to manually observe ejection of the ink 9 from the nozzle holes Hn in advance in order to set the pulse in the drive signal Sd, which requires an enormous amount of time and labor. Therefore, it is as follows. That is, there is a possibility that convenience for the user will be impaired.

(C-2. Present embodiment)
Therefore, in the inkjet head 4 of the present embodiment, the drive signal Sd is generated as needed (automatically generated) in the signal generator 48 . Specifically, the signal generator 48 obtains the pulse width Wp and the voltage value Vp of the pulses (such as the aforementioned pulses Pa, Pb, and Pc) in the driving signal Sd, and has the obtained pulse width Wp and voltage value Vp. The pulse is used to generate the drive signal Sd. The process of generating such a drive signal Sd will be described in detail below.

FIG. 8 is a flow chart showing the process of generating the drive signal Sd and the like according to the present embodiment. Of the series of processes (steps S10 to S17 to be described later) shown in FIG. 8, each process of steps S11 to S16 to be described later corresponds to the process of generating the drive signal Sd.

FIG. 9 is a timing chart showing examples of waveforms of various signals during the process of generating the drive signal Sd shown in FIG. Specifically, in FIG. 9, (A) indicates the measurement start signal Sm indicating the measurement start timing in the acoustic measurement unit 47, (B) and (C) indicate the above-described acoustic signals Sacout and Sacin, respectively, ( D) and (E) show the instantaneous amplitude signal S2 and the time difference signal S3, respectively. In FIG. 9, the horizontal axis indicates time t.

In the series of processes shown in FIG. 8, first, as a preliminary step, the signal generator 48 determines whether or not it is necessary to generate (update) the drive signal Sd (step S10). If it is determined that the drive signal Sd needs to be generated (step S10: Y), the process proceeds to the drive signal Sd generation process (steps S11 to S16) described below. On the other hand, if it is determined that generation of the drive signal Sd is not necessary (step S10: N), the process proceeds to step S17, which will be described later, and the ink 9 is ejected based on the current drive signal Sd. It will be.

Examples of cases where the drive signal Sd needs to be generated include the following cases. That is, for example, when a predetermined time elapses, when a cartridge of the ink tank 3 is installed, or when a predetermined operation signal is input from the user to the printer 1, the non-ejection period (idle period) of the ink 9 is set. When it becomes more than predetermined time, etc. are mentioned.

Next, in the process of generating the drive signal Sd (steps S11 to S16), the signal generator 48 performs the process of calculating the pulse width Wp of the pulse (steps S11 to S13) and the process of calculating the voltage value Vp of the pulse (steps S14 to S14). S15) are performed in parallel (see FIG. 8).

(Steps S11 to S13: Processing for calculating pulse width Wp)
Here, in the process of calculating the pulse width Wp, first, the signal generator 48 obtains the arrival time Δt of the acoustic signal Sac in the ink 9 (step S11). That is, for example, as shown in FIG. 9, the signal generation unit 48 generates a signal from the rising timing (timing t1) of the measurement start signal Sm to the timing (timing t2) at which the instantaneous amplitude signal S2 exhibits the peak value (amplitude A2). An arrival time Δt corresponding to the time difference is obtained. Specifically, the counter circuit 484 in the signal generator 48 obtains such arrival time Δt by the method described above (see FIG. 5).

Next, the signal generation unit 48 obtains the speed of sound Vs in the ink 9 based on the arrival time Δt thus obtained (step S12). Specifically, since the acoustic signal generation unit 485 in the signal generation unit 48 obtains the sound wave cycle Tac (see FIG. 9B) by the method described above, the sound wave cycle Tac and the ultrasonic wave transmitter 471 to the ultrasonic receiver 472 and the physical distance from .

Subsequently, the signal generator 48 obtains the pulse width Wp of the pulse based on the sound velocity Vs in the ink 9 thus obtained (step S13). Specifically, the waveform setting section 487 in the signal generation section 48 sets the pulse width Wp based on such sound velocity Vs (see FIG. 5).

Here, with reference to FIG. 10, a method for setting such a pulse width Wp will be described. FIG. 10 schematically shows an overview of the method of setting the pulse width Wp and the like.

First, when considering maximizing the ejection speed (ejection speed) of the ink 9, for example, as shown in FIG. is defined by the following equation (5). Then, by using this equation (5), the pulse width Wp (on-pulse peak (AP): see FIG. 10) for maximizing the ejection speed of the ink 9 can be obtained.
(2×Wp)=(2×L)/(N×Vs) (N=1, 2, 3, …) ……(5)

Incidentally, this AP corresponds to a half period of the natural vibration period of the ink 9 in the ejection channel Ce (1AP=(natural vibration period of the ink 9)/2). When the pulse width Wp is set to this AP, as described above, the ejection speed (ejection efficiency) of the ink 9 is maximized when one droplet of the ink 9 is normally ejected (one droplet ejection). Become. It should be noted that this AP is defined by, for example, the shape of the ejection channel Ce and the physical properties (specific gravity, etc.) of the ink 9 .

(Steps S14 and S15: Processing for calculating voltage value Vp)
On the other hand, in the process of calculating the voltage value Vp, first, the signal generator 48 obtains the degree of attenuation At of the acoustic signal Sac in the ink 9 (step S14). Specifically, the attenuation calculation unit 486 in the signal generation unit 48 calculates the difference between the amplitude A2 of the instantaneous amplitude signal S2 (corresponding to the amplitude of the acoustic signal Sacin) and the amplitude A1 of the acoustic signal Sacout by the method described above. Attenuation At is obtained (see FIG. 9).

Next, the signal generator 48 obtains the voltage value Vp in the pulse based on the attenuation degree At thus obtained (step S15). Specifically, the waveform setting section 487 in the signal generation section 48 sets the voltage value Vp based on such attenuation At (see FIG. 5). At this time, the signal generator 48 may control the voltage value Vp (voltage control) in consideration of the actuator temperature Tpzt detected by the temperature detector 45 .

Here, such attenuation of the amplitude between the acoustic signals Sacout and Sacin occurs due to the viscous resistance of the ink 9, etc., as described above, and when the acoustic signal Sac passes through the ink 9, It represents the amount of energy loss that occurs in Such energy loss of ultrasonic waves generally includes scattering attenuation due to nonuniformity of the medium due to air bubbles in the liquid, and absorption attenuation due to viscous resistance. Inks used in printers are usually degassed, so the main factor of energy loss in this case is viscous resistance.

Further, for example, when the ink ejection speed is kept within a predetermined range, there is a very strong correlation between the temperature dependence of the ink viscosity and the temperature dependence of the drive voltage required at that time. It has been known. This also shows that the viscous resistance of the ink is strongly related to the loss of ultrasonic energy.

From these facts, it can be said that an appropriate drive voltage (pulse voltage value Vp) can be obtained based on the attenuation At representing the energy loss of the ultrasonic waves.

When setting the voltage value Vp based on this attenuation At, for example, the physical characteristics of means for obtaining acoustic energy for ejecting the ink 9, the electromechanical characteristic values of the actuator plate 42 (piezoelectric body) information such as is required. Therefore, when setting the voltage value Vp based on the attenuation At, a predetermined correction function, a lookup table for correction, or the like may be used. Alternatively, information defining the relationship between the attenuation At and the voltage value Vp may be stored in advance in the signal generator 48, and the rate of change of the voltage value Vp may be obtained from the rate of change of the attenuation At. .

(Steps S16 and S17: Generation of drive signal Sd, ejection operation of ink 9)
Subsequently, the signal generator 48 uses the pulse having the pulse width Wp and the voltage value Vp thus obtained to generate the drive signal Sd, for example, as shown in FIG. 4 (step S16). ). Then, the signal generator 48 applies such a drive signal Sd to the actuator plate 42 to eject the ink 9 from the nozzle holes Hn (step S17). In this manner, the ejection operation of the ink 9 described above is performed.

With this, the series of processes shown in FIG. 8 is completed.

(C-3. Action and effect)
In this manner, in the inkjet head 4 of the present embodiment, the transmitter (ultrasonic transmitter 471) and the receiver (ultrasonic receiver 472) of the ultrasonic acoustic signal Sac in the ink 9 in the acoustic measurement unit 47 ), the pulse of the drive signal Sd is set. Then, a drive signal Sd is generated using the set pulse, and the generated drive signal Sd is applied to the actuator plate 42, whereby the ink 9 is ejected from the nozzle holes Hn in the nozzle plate 41. . That is, the ejection operation of the ink 9 is performed using the drive signal Sd automatically generated in the inkjet head 4 using the acoustic signal Sac of the ultrasonic wave.

As a result, in the present embodiment, unlike the above-described comparative example, etc., it is as follows. In other words, it is not necessary to manually observe ejection of the ink 9 from the nozzle holes Hn in advance in order to set the pulses in the drive signal Sd. Therefore, a pulse (driving signal Sd) suitable for the driving conditions at that time can be automatically generated in the inkjet head 4 at any time without requiring an enormous amount of time and effort.

As described above, in the present embodiment, it is possible to improve convenience for users (end users, etc.) as compared with the above-described comparative example. In addition, for example, it is possible to significantly reduce investment in equipment for measurement and fixed costs, which are separately required when observing ejection of the ink 9 described above. Furthermore, the degree of freedom in selecting the ink 9 can be greatly improved, and the degree of freedom in using the printer 1 for the user can also be improved.

Further, in the present embodiment, the sonic velocity Vs in the ink 9 is obtained based on the arrival time Δt of the ultrasonic acoustic signal Sac, and the pulse width Wp of the pulse is determined based on the sonic velocity Vs in the ink 9. As required, it is as follows. That is, as a result of generating pulses that are set more appropriately for the drive conditions, it is possible to improve the ejection stability of the ink 9 .

Furthermore, in the present embodiment, the attenuation At in the ultrasonic acoustic signal Sac is obtained, the voltage value Vp of the pulse is obtained based on the attenuation At, and the obtained voltage value Vp and pulse width Wp are obtained. The pulses are used to generate the drive signal Sd. That is, a pulse having a pulse width Wp determined based on the speed of sound Vs in the ink 9 and a voltage value Vp determined based on the attenuation At is automatically generated within the inkjet head 4 . In this way, in addition to the pulse width Wp described above, the voltage value Vp that contributes to the ejection characteristics of the ink 9 is also automatically adjusted. It will be automatically generated. Therefore, it is possible to further improve the convenience for the user.

<2. Variation>
Next, modifications (modifications 1 and 2) of the above embodiment will be described. The same reference numerals are assigned to the same components as those in the above-described embodiment, and the description thereof will be omitted as appropriate.

[Modification 1]
FIG. 11 is a block diagram showing a schematic configuration example of a printer 1a as a liquid jet recording apparatus according to Modification 1. As shown in FIG. The printer 1a of Modification 1 corresponds to the printer 1 of the embodiment provided with an inkjet head 4a instead of the inkjet head 4, which will be described below.

Note that the printer 1a corresponds to a specific example of a "liquid jet recording apparatus" in the present disclosure. Further, the inkjet head 4a corresponds to a specific example of the "liquid jet head" in the present disclosure.

In the inkjet head 4a of Modification 1, as shown in FIG. 11, the arrangement position of the acoustic measurement section 47 is changed from the inkjet head 4 (see FIG. 3) of the embodiment, and a part of the acoustic measurement section 47 is It is provided inside the actuator plate 42 . Specifically, in the example of FIG. 11, an ultrasonic transmitter 471 and an ultrasonic receiver 472 in the acoustic measurement section 47 are arranged inside the actuator plate 42 respectively. Incidentally, other parts in the acoustic measurement unit 47 (for example, a predetermined amplifier, a digital-to-analog conversion circuit (DAC: Digital to Analog Converter), an analog-to-digital conversion circuit (ADC: Analog to Digital Converter), etc.) It is arranged outside the plate 42 .

In the modified example 1 having such a configuration as well, it is possible to obtain the same effect by basically the same action as in the embodiment.

In addition, particularly in this modified example 1, since a part of the acoustic measurement unit 47 is provided inside the actuator plate 42 , the acoustic signal Sac of the ultrasonic wave can be detected in the ink 9 at a location close to the ejection environment of the ink 9 . will be made and received respectively. As a result, compared to the inkjet head 4 of the embodiment, the drive signal Sd suitable for the ink 9 can be generated more easily, so that the user's convenience can be further improved.

In this first modification, the case where a part of the acoustic measurement unit 47 is provided inside the actuator plate 42 has been described as an example. It may be provided inside. Further, for example, part or all of the acoustic measurement unit 47 may be arranged inside both the actuator plate 42 and the nozzle plate 41 .

[Modification 2]
FIG. 12 is a block diagram showing a schematic configuration example of a printer 1b as a liquid jet recording apparatus according to Modification 2. As shown in FIG. The printer 1b of Modification 2 corresponds to the printer 1 of the embodiment provided with an inkjet head 4b instead of the inkjet head 4, which will be described below.

The printer 1b corresponds to a specific example of "liquid jet recording apparatus" in the present disclosure.

As shown in FIG. 12, the inkjet head 4b of Modification 2 is different from the inkjet head 4 of the embodiment (see FIG. 3) in that the acoustic measuring unit 47 and the signal generating unit 48 are provided outside the inkjet head 4b. It corresponds to what was set. In other words, both the sound measuring section 47 and the signal generating section 48 are arranged outside the inkjet head 4b in the printer 1b. Accordingly, the inkjet head 4b of Modification 2 is provided with only the nozzle plate 41, the actuator plate 42, the temperature detection section 45, and the drive section 49 (see FIG. 12).

Since the printer 1b as a whole has the same configuration as the printer 1 and the printer 1a described so far, the same operation as in the first embodiment and the first modification can be achieved in the second modification with such a configuration. , it is possible to obtain a similar effect.

In addition, especially in this modified example 2, since the acoustic measurement section 47 and the signal generation section 48 are provided outside the inkjet head 4b, it is possible to obtain the following effects, for example. That is, even if the inkjet head 4b having the existing configuration is used, for example, the drive signal Sd can be generated as described above by arranging the acoustic measurement unit 47 and the signal generation unit 48 in the printer 1b. processing and the like can be realized.

<3. Other modified examples>
Although the present disclosure has been described above with reference to the embodiments and modifications, the present disclosure is not limited to these embodiments and the like, and various modifications are possible.

For example, in the above embodiments and the like, specific examples of the configuration (shape, arrangement, number, etc.) of each member in the printer and the inkjet head have been described, but they are not limited to those described in the above embodiments and the like. , other shapes, arrangements, numbers, and the like. Specifically, for example, a nozzle hole Hn on the nozzle plate 41 or a dummy nozzle hole separately provided on the nozzle plate 41 is used to perform measurement by the ultrasonic transmitter 471 and the ultrasonic receiver 472. can be In the above embodiments and the like, a shuttle type printer in which the inkjet head moves has been described as an example, but the present invention is not limited to this example. good too. Furthermore, in the above-described embodiments and the like, the case where the ink tank is housed in a predetermined housing has been described as an example, but the present invention is not limited to this example, and the ink tank may be arranged outside the housing. can be In addition, one of the sound measurement unit 47 and the signal generation unit 48 may be arranged inside the printer (outside the inkjet head) and the other inside the inkjet head.

Moreover, as the structure of the inkjet head, it is possible to apply each type. That is, for example, a so-called side-shoot type inkjet head that ejects the ink 9 from the central portion of the actuator plate in the extending direction of each ejection channel may be used. Alternatively, for example, a so-called edge shoot type inkjet head that ejects the ink 9 along the extending direction of each ejection channel may be used. Furthermore, the printer method is not limited to the method described in the above embodiment, etc., and various methods such as a thermal method (thermal method on demand type) and MEMS (Micro Electro Mechanical Systems) method are applied. It is possible to

Furthermore, in the above-described embodiments and the like, a non-circulating inkjet head that utilizes the ink 9 between the ink tank and the inkjet head without being circulated has been described as an example, but the present invention is not limited to this example. . That is, for example, the present disclosure can also be applied to a circulating inkjet head that circulates the ink 9 between the ink tank and the inkjet head.

In addition, in the above embodiments and the like, specific examples of the process of generating the driving signal Sd by the signal generation unit 48 and the like have been described, but the examples are not limited to the examples given in the above embodiments and the like. Alternatively, the process of generating the driving signal Sd may be performed using the method. Specifically, for example, in the above embodiments and the like, both the pulse width Wp and the voltage value (peak value) Vp of the pulse are set (automatically adjusted), and then the drive signal Sd is generated as an example. Although described, it is not limited to this example. That is, for example, out of the pulse width Wp and the voltage value Vp of the pulse, only one of the pulse width Wp and the voltage value Vp may be set before the drive signal Sd is generated. In addition, in the above-described embodiment and the like, a sine wave is used as the acoustic signal Sac, but the present invention is not limited to this example, and the acoustic signal Sac may be configured using, for example, a pulse-shaped waveform. In this case, it is possible to perform measurement in the acoustic measurement unit 47 using the actual waveform shape used for ejecting the ink 9 .

Further, in the above-described embodiment and the like, the case where the pulses (pulses Pa, Pb, Pc) for expanding the volume in each ejection channel are pulses (positive pulses) for expanding during the high state period has been described. However, it is not limited to this case. That is, not only is the pulse expanded during the high state period and contracted during the low state period, but conversely, the pulse is expanded during the low state period and contracted during the high state period (negative pulse). may be

Further, for example, during the OFF period immediately after the ON period, a pulse may be additionally applied for assisting droplet ejection. Examples of the pulse for assisting the ejection of droplets include a pulse for shrinking the volume in each ejection channel and a pulse for pulling back part of the ejected droplet (auxiliary pulse). . Also, the pulse (main pulse) applied immediately before the latter auxiliary pulse has, for example, a pulse width equal to or less than the width of the on-pulse peak (AP). It should be noted that even if such a pulse for assisting droplet ejection is added, it does not affect the content (driving method, etc.) of the present disclosure that has been described so far.

Also, the series of processes described in the above embodiments and the like may be performed by hardware (circuit) or by software (program). When it is performed by software, the software consists of a program group for executing each function by a computer. Each program, for example, may be installed in the computer in advance and used, or may be installed in the computer from a network or a recording medium and used.

Furthermore, in the above embodiments and the like, the printer 1 (inkjet printer) was described as a specific example of the "liquid jet recording apparatus" in the present disclosure, but the invention is not limited to this example, and other devices other than inkjet printers may be used. The present disclosure can also be applied to devices. In other words, the "liquid jet head" (inkjet head) of the present disclosure may be applied to devices other than inkjet printers. Specifically, for example, the "liquid jet head" of the present disclosure may be applied to devices such as facsimiles and on-demand printers.

Additionally, the various examples described so far may be applied in any combination.

Note that the effects described in this specification are merely examples and are not limited, and other effects may be provided.

In addition, the present disclosure can also be configured as follows.
(1)
an injection unit having a plurality of nozzles for injecting liquid;
a drive unit for ejecting the liquid from the nozzle by applying a drive signal having one or more pulses to the ejection unit;
an acoustic measurement unit having a transmitter that transmits an ultrasonic acoustic signal into the liquid, and a receiver that receives the ultrasonic acoustic signal from the liquid;
and a signal generator that generates the drive signal,
The signal generator is
setting the pulse based on a comparison of signals at the transmitter and the receiver in the acoustic measurement unit;
A liquid jet head that generates the drive signal using the set pulse.
(2)
The signal generator is
Obtaining the speed of sound in the liquid based on the arrival time in the liquid from the transmitter to the receiver of the ultrasonic acoustic signal,
Obtaining a pulse width in the pulse based on the obtained speed of sound in the liquid,
The liquid jet head according to (1) above, wherein the drive signal is generated using the pulse having the obtained pulse width.
(3)
The signal generator is
Obtaining the degree of attenuation in the liquid from the transmitter to the receiver in the acoustic signal of the ultrasonic wave;
further obtaining a crest value of the pulse based on the obtained degree of attenuation;
The liquid jet head according to (2) above, wherein the drive signal is generated using the pulse having the obtained peak value and pulse width.
(4)
The liquid jet head according to any one of (1) to (3), wherein at least part of the acoustic measurement section is provided inside the ejection section.
(5)
A liquid jet recording apparatus comprising the liquid jet head according to any one of (1) to (4) above.
(6)
A system for generating a drive signal having one or more pulses to be applied to an ejector having a plurality of nozzles for ejecting liquid, the system comprising:
an acoustic measurement unit having a transmitter that transmits an ultrasonic acoustic signal into the liquid, and a receiver that receives the ultrasonic acoustic signal from the liquid;
and a signal generator that generates the drive signal,
The signal generator is
setting the pulse based on a comparison of signals at the transmitter and the receiver in the acoustic measurement unit;
A drive signal generation system that generates the drive signal using the set pulse.

1, 1a, 1b... Printer 10... Housing 2a, 2b... Conveying mechanism 21... Grid roller 22... Pinch roller 3 (3Y, 3M, 3C, 3K)... Ink tank 4 (4Y, 4M, 4C) , 4K), 4a, 4b... inkjet head, 41... nozzle plate, 42... actuator plate, 45... temperature detector, 47... acoustic measurement part, 471... ultrasonic transmitter, 472... ultrasonic receiver, 48... signal Generator 481 Bandpass filter 482 Analysis signal generator 482a Hilbert transform circuit 482b Delay circuit 483 Amplitude signal generator 484 Counter circuit 485 Acoustic signal generator 486 Attenuation Operation unit 487 Waveform setting unit 49 Driving unit 50 Ink supply tube 6 Scanning mechanism 61a, 61b Guide rail 62 Carriage 63 Driving mechanism 631a, 631b Pulleys 632 Endless Belt 633 Drive motor 9 Ink P Recording paper d Conveying direction Hn Nozzle hole Ce Ejection channel Sd Drive signal Vd Drive voltage Tpzt Actuator temperature Wp Pulse width , Vp... Voltage value (peak value), Vs... Sound speed, Pa, Pb, Pc... Pulse, Sac, Sacin, Sacout... Acoustic signal, S0... Signal, S1a, S1b... Analysis signal, S2... Instantaneous amplitude signal, S3... Time difference signal, Sm... measurement start signal, A1, A2... amplitude, At... degree of attenuation, L... channel length, t... time, t1, t2... timing, ?t... arrival time, Tac... sound wave period.

Claims (4)

an injection unit having a plurality of nozzles for injecting liquid;
a drive unit for ejecting the liquid from the nozzle by applying a drive signal having one or more pulses to the ejection unit;
an acoustic measurement unit having a transmitter that transmits an ultrasonic acoustic signal into the liquid, and a receiver that receives the ultrasonic acoustic signal from the liquid;
a signal generation unit that generates the drive signal based on a comparison of signals in the transmitter and the receiver in the acoustic measurement unit ;
The signal generator is
Based on the arrival time in the liquid from the transmitter to the receiver of the ultrasonic acoustic signal, the speed of sound in the liquid is obtained, and based on the obtained speed of sound in the liquid, the find the pulse width in the pulse,
Obtaining the degree of attenuation in the liquid from the transmitter to the receiver in the acoustic signal of the ultrasonic wave, and obtaining the crest value of the pulse based on the obtained degree of attenuation,
The liquid ejecting head generates the drive signal using the pulse having the obtained pulse width and crest value . 2. The liquid jet head according to claim 1 , wherein at least part of the acoustic measurement section is provided inside the jetting section. A liquid jet recording apparatus comprising the liquid jet head according to claim 1 . A system for generating a drive signal having one or more pulses to be applied to an ejector having a plurality of nozzles for ejecting liquid, the system comprising:
an acoustic measurement unit having a transmitter that transmits an ultrasonic acoustic signal into the liquid, and a receiver that receives the ultrasonic acoustic signal from the liquid;
a signal generation unit that generates the drive signal based on a comparison of signals in the transmitter and the receiver in the acoustic measurement unit ;
The signal generator is
Based on the arrival time in the liquid from the transmitter to the receiver of the ultrasonic acoustic signal, the speed of sound in the liquid is obtained, and based on the obtained speed of sound in the liquid, the find the pulse width in the pulse,
Obtaining the degree of attenuation in the liquid from the transmitter to the receiver in the acoustic signal of the ultrasonic wave, and obtaining the crest value of the pulse based on the obtained degree of attenuation,
A drive signal generation system for generating the drive signal using the pulse having the determined pulse width and crest value .

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