Patent Application
20200094554
The present application is based on, and claims priority from JP Application Serial Number 2018-177075, filed Sep. 21, 2018, the disclosure of which is hereby incorporated by reference herein in its entirety.
The present disclosure relates to a liquid ejecting apparatus.
In a liquid ejecting apparatus such as an ink jet printer, as a piezoelectric element provided in a discharge portion of the liquid ejecting apparatus is driven by a driving signal, a liquid such as ink, which is filled in a compression chamber provided in the discharge portion, is discharged, so that an image is formed on a recording medium. The image quality of the image formed by such a liquid ejecting apparatus is affected by the viscosity of the liquid in the compression chamber. Therefore, in order to maintain good image quality of the image formed by the liquid ejecting apparatus, it is necessary to grasp the viscosity of the liquid in the compression chamber. For example, a technology, which specifies a time until residual vibration occurring in the discharge portion after the piezoelectric element is driven by the driving signal is attenuated and grasps viscosity of the liquid in the compression chamber based on a result of the specification, is disclosed in JP-A-2011-189656.
In the related art, the amplitude of residual vibration occurring in a discharge portion varies due to superposition or the like of noise on a driving signal. Then, when the amplitude of the residual vibration occurring in the discharge portion varies, a time until the residual vibration occurring in the discharge portion is attenuated also varies. Therefore, in the related art, it is difficult to accurately grasp the viscosity of liquid in a compression chamber.
According to an aspect of the present disclosure, there is provided a liquid ejecting apparatus including a discharge portion provided with a piezoelectric element that is driven by a driving signal and a compression chamber that discharges a liquid from a nozzle according to the driving of the piezoelectric element, a detection unit detecting residual vibration occurring in the discharge portion, in a detection period after the piezoelectric element is driven and outputting a residual vibration signal indicating a waveform of the residual vibration, a specification unit specifying an initial time from a start time when the detection period starts to a reference time when a residual vibration signal becomes a signal level of a center of an amplitude after the start time of the detection period, and an estimation unit estimating a viscosity of the liquid in the compression chamber, based on the initial time.
Hereinafter, an aspect for carrying out the present disclosure will be described with reference to the accompanying drawings. However, in each drawing, the dimension and the scale of each component are appropriately different from the actual ones. Further, since the embodiment described below is a preferable specific example of the present disclosure, various technically preferable limitations are added. However, the scope of the present disclosure is not limited to the embodiment as long as there is no statement for particularly limiting the present disclosure in the following description.
In the present embodiment, a liquid ejecting apparatus will be described by exemplifying an ink jet printer that forms an image on a recording paper sheet P by ejecting ink. In the present embodiment, the ink is an example of “liquid”, and the recording paper sheet P is an example of a “medium”.
Hereinafter, a configuration of an ink jet printer 1 according to the present embodiment will be described with reference to
As shown in
In the present embodiment, as shown in
The control unit 2 includes a CPU. However, the control unit 2 may include a programmable logic device such as an FPGA instead of the CPU or in addition to the CPU. Here, the CPU is an abbreviation of a central processing unit, and the FPGA is an abbreviation of a field-programmable gate array. The control unit 2 causes the CPU to operate according to a control program stored in the storage unit 5 so as to generate a signal for controlling an operation of each component of the ink jet printer 1, such as a printing signal SI and a waveform designation signal dCom.
Here, the waveform designation signal dCom is a digital signal that defines a waveform of the driving signal Com.
Further, the driving signal Com is an analog signal that drives the discharge portion D. The driving signal generating circuit 5 includes a DA converting circuit, and generates the driving signal Com having a waveform defined by the waveform designation signal dCom. In the present embodiment, it is assumed that the driving signal Com includes a driving signal Com-A and a driving signal Com-B.
Further, the printing signal SI is a digital signal for designating the type of an operation of the discharge portion D. In detail, the printing signal SI is a signal that designates the type of the operation of the discharge portion D by designating whether or not the driving signal Com is supplied to the discharge portion D.
As shown in
The recording head 32 includes M discharge portions D. Here, the value M is a natural number satisfying “M≥1”. Hereinafter, an m-th discharge portion D among the M discharge portions D provided in the recording head 32 may be referred to as a discharge portion D[m]. Here, the variable m is a natural number satisfying “1≤m≤M”. Further, in the following description, when a component or a signal of the ink jet printer 1 corresponds to the discharge portion D[m] among the M discharge portions D, the suffix [m] may be added to a reference numeral to represent the component, the signal, or the like.
The switch circuit 31 switches supply of the driving signal Com to the discharge portion D[m] based on the printing signal SI. Hereinafter, the driving signal Com supplied to the discharge portion D[m] among the driving signal Com may be referred to as a supply driving signal Vin[m]. Further, the switch circuit 31 switches supply, to the detection circuit 33, of a detection potential signal Vout[m] indicating a potential of an upper electrode Zu[m] of a piezoelectric element PZ[m] provided in the discharge portion D[m] based on the printing signal SI. The piezoelectric element PZ[m] and the upper electrode Zu[m] will be described below with reference to
The detection circuit 33 generates a residual vibration signal Vd[m] based on the detection potential signal Vout[m]. The residual vibration signal Vd[m] represents a waveform of residual vibration that is vibration remaining in the discharge portion D[m] after the discharge portion D[m] is driven by the supply driving signal Vin[m]. The detection circuit 33 is an example of a “detection unit”.
Further, as described above, as shown in
The time specifying circuit 61 generates time information NTC indicating an initial time TK[m], which will be described below, based on the residual vibration signal Vd[m]. The time specifying circuit 61 is an example of a “specification unit”.
The viscosity estimating circuit 62 estimates the viscosity of the ink existing inside the discharge portion D based on the time information NTC, and generates viscosity information NND indicating the estimated viscosity of the ink. The viscosity estimating circuit 62 is an example of an “estimation unit”.
Hereinafter, processing related to the generation of the viscosity information NND in the estimation unit JU may be referred to as viscosity estimating processing. Further, in the following description, for the viscosity estimating processing, the discharge portion D[m], which is a target of detection of the detection potential signal Vout[m] by the detection circuit 33, may be referred to as the estimation target discharge portion D-S.
As shown in
Hereinafter, a +X direction and a −X direction that is opposite to the +X direction are collectively referred to as an “X axis direction”, a +Y direction intersecting the X axis direction and a −Y direction that is opposite to the +Y direction are collectively referred to as an “Y axis direction”, and a +Z direction intersecting the X axis direction and the Y axis direction and a −Z direction that is opposite to the +Z direction are collectively referred to as a “Z axis direction”. Then, in the present embodiment, as shown in
As shown in
Further, as described above, the ink jet printer 1 according to the present embodiment includes a transport mechanism 7. When the printing processing is performed, the transport mechanism 7 changes the relative position of the recording paper sheet P to the head module 3 by causing the carriage 300 to reciprocate in the Y axis direction and transporting the recording paper sheet P in the +X direction, and thus can land the ink on the entire recording paper sheet P. As shown in
In the present embodiment, as shown in
Here, an outline of an operation of the control unit 2 when the printing processing is performed will be described.
When the printing processing is performed, the control unit 2 first causes the storage unit 5 to store the printing data Img supplied from the host computer. Next, the control unit 2 generates a signal for controlling the head unit HU such as the printing signal SI, a signal for controlling the driving signal generating circuit 4 such as the waveform designation signal dCom, and a signal for controlling the transport mechanism 7, based on various pieces of data stored in the storage unit 5, such as the printing data Img. Then, the control unit 2 controls the driving signal generating circuit 4 and the switch circuit 31 to drive the discharge portion D while controlling the transport mechanism 7 to change the relative position of the recording paper sheet P to the head module 3, based on various signals such as the printing signal SI and various pieces of data stored in the storage unit 5. Accordingly, the control unit 2 adjusts presence and absence of the ink from the discharge portion D, a discharge amount of the ink, a discharge timing of the ink, and the like, and controls each component of the ink jet printer 1 to perform the printing processing of forming an image corresponding to the printing data Img on the recording paper sheet P.
Further, the ink jet printer 1 according to the present embodiment performs the viscosity estimating processing.
The viscosity estimating processing is a series of processing executed by the ink jet printer 1, which includes processing in which the control unit 2 selects the estimation target discharge portion D-S that is a target of the viscosity estimating processing, processing in which the driving signal generating circuit 4 generates the driving signal Com based on the waveform designation signal dCom output from the control unit 2, processing in which the switch circuit 31 drives the estimation target discharge portion D-S by supplying the driving signal Com output from the control unit 2 to the estimation target discharge portion D-S as the supply driving signal Vin under a control of the control unit 2, processing in which the detection circuit 33 generates the residual vibration signal Vd according to the detection potential signal Vout indicating the residual vibration occurring in the estimation target discharge portion D-S, processing in which the time specifying circuit 61 generates the time information NTC based on the residual vibration signal Vd, and processing in which the viscosity estimating circuit 62 estimates the viscosity of the ink existing inside the estimation target discharge portion D-S based on the time information NTC, and generates the viscosity information NND indicating the estimated viscosity of the ink.
The recording head 32 and the discharge portion D provided in the recording head 32 will be described with reference to
As shown in
Hereinafter, a configuration of each head unit HU will be described with reference to
As shown in
The connection state designating circuit 311 generates a connection state designating signal Ga[m] that designates an ON/OFF state of the switch Ra[m], a connection state designating signal Gb[m] that designates an ON/OFF state of the switch Rb[m], and a connection state designating signal Gs[m] that designates an ON/OFF state of the switch Rs[m], based on at least some of the printing signal SI, a latch signal LAT, a change signal CH, and a period defining signal Tsig supplied from the control unit 2.
Here, the switch Ra[m] switches conduction and non-conduction between the wire La and the upper electrode Zu[m] of the piezoelectric element PZ[m] provided in the discharge portion D[m], based on the connection state designating signal Ga[m]. In the present embodiment, the switch Ra[m] is switched on when the connection state designating signal Ga[m] is at a high level and is switched off when the connection state designating signal Ga[m] is at a low level. Further, the switch Rb[m] switches conduction and non-conduction between the wire Lb and the upper electrode Zu[m] of the piezoelectric element PZ[m] provided in the discharge portion D[m], based on the connection state designating signal Gb[m]. In the present embodiment, the switch Rb[m] is switched on when the connection state designating signal Gb[m] is at a high level and is switched off when the connection state designating signal Gb[m] is at a low level. Further, the switch Rs[m] switches conduction and non-conduction between the wire Ls and the upper electrode Zu[m] of the piezoelectric element PZ[m] provided in the discharge portion D[m], based on the connection state designating signal Gs[m]. In the present embodiment, the switch Rs[m] is switched on when the connection state designating signal Gs[m] is at a high level and is switched off when the connection state designating signal Gs[m] is at a low level.
As described above, the supply driving signal Vin[m] is a signal that is supplied to the piezoelectric element PZ[m] of the discharge portion D[m] through the switch Ra[m] or Rb[m] among the driving signals Com-A and Com-B.
The detection potential signal Vout[m] indicating the potential of the piezoelectric element PZ[m] of the discharge portion D[m] driven as the estimation target discharge portion D-S is supplied to the detection circuit 33 through the wire Ls. The detection circuit 33 generates the residual vibration signal Vd[m] based on the detection potential signal Vout[m].
Hereinafter, an operation of each head unit HU will be described with reference to
In the present embodiment, an operation period of the ink jet printer 1 includes one or more unit periods Tu. Further, the ink jet printer 1 according to the present embodiment can drive each discharge portion D for the printing processing in each unit period Tu. Further, the ink jet printer 1 according to the present embodiment can drive the estimation target discharge portion D-S in the viscosity estimating processing and detect the detection potential signal Vout from the estimation target discharge portion D-S, in each unit period Tu.
As shown in
Further, the control unit 2 outputs the change signal CH having a pulse PlsC in the unit period Tu. Then, the control unit 2 divides the unit period Tu into a control period Tu1 from the rising of the pulse PlsL to rising of the pulse PlsC and a control period Tu2 from the rising of the pulse PlsC to the rising of the pulse PlsL.
Further, the control unit 2 outputs the period defining signal Tsig having a pulse PlsT1 and a pulse PlsT2 in the unit period Tu. Then, the control unit 2 divides the unit period Tu into a control period TSS1 from the rising of the pulse PlsL to rising of the pulse PlsT1, a control period TSS2 from the rising of the pulse PlsT1 to rising of the pulse PlsT2, and a control period TSS3 from the rising of the pulse PlsT2 to the rising of the pulse PlsL.
The printing signal SI according to the present embodiment includes individual designation signals Sd[1] to Sd[M] that designate driving modes of the discharge portions D[1] to D[M] in each unit period Tu. When the printing processing or the viscosity estimating processing is performed in the unit period Tu, as shown in
In the present embodiment, it is assumed that the discharge portion D[m] can form a large dot, a medium dot that is smaller than the large dot, and a small dot that is smaller than the medium dot. Then, in the present embodiment, it is assumed that the individual designation signal Sd[m] can select any one of five values of a value “1” that designates driving of a mode in which the amount of the ink, corresponding to the large dot, is discharged to the discharge portion D[m], a value of ‘2” that designates driving of a mode in which the amount of the ink, corresponding to the middle dot, is discharged to the discharge portion D[m], a value of “3” that designates driving of a mode in which the amount of the ink, corresponding to the small dot, is discharged to the discharge portion D[m], a value of “4” that designates driving of a mode in which the ink is not discharged to the discharge portion D[m], and a value of “5” that designates driving of the estimation target discharge portion D-S with respect to the discharge portion D[m], in the unit period Tu.
As shown in
In the present embodiment, it is assumed as an example that, when the potential of the supply driving signal Vin[m] supplied to the discharge portion D[m] is a high potential, the volume of the cavity 322 of the discharge portion D[m] is smaller, as compared to a case where the potential of the supply driving signal Vin[m] is a low potential. Therefore, when the discharge portion D[m] is driven by the supply driving signal Vin[m] having the waveform PX, the potential of the supply driving signal Vin[m] is changed from the lowest potential VLx to the highest potential VHx, and thus the ink in the discharge portion D[m] is discharged from the nozzle N. Further, when the discharge portion D[m] is driven by the supply driving signal Vin[m] having the waveform PY, the potential of the supply driving signal Vin[m] is changed from the lowest potential VLy to the highest potential VHy, and thus the ink in the discharge portion D[m] is discharged from the nozzle N.
Further, in the present embodiment, the driving signal Com-B has the waveform PS. In the present embodiment, the waveform PS is a waveform that is the reference potential V0 at a time when the control period TSS1 starts, is maintained at a potential VS1 that is higher than the reference potential V0 during a period T1 among the control period TSS1, is changed from the potential VS1 to a potential VS2 that is lower than the reference potential V0 during a period Tp1 after the period T1 among the control period TSS1, is maintained at the potential VS2 during a period T2 after the period Tp1 among the control period TSS1, is maintained at the potential VS2 during the control period TSS2, and is changed from the potential VS2 to the reference potential V0 during the control period TSS3.
In the present embodiment, when the discharge portion D[m] is driven by the supply driving signal Vin[m] having the waveform PS, the volume of the cavity 322 of the discharge portion D[m] when the potential of the supply driving signal Vin[m] is the potential VS1 is smaller than the volume of the cavity 322 of the discharge portion D[m] when the potential of the supply driving signal Vin[m] is the potential VS2. In other words, in the present embodiment, when the discharge portion D[m] is driven by the supply driving signal Vin[m] having the waveform PS, the volume of the cavity 322 of the discharge portion D[m] is enlarged in the period Tp1 and the ink in the discharge portion D[m] is drawn in the +Z direction in the period Tp1.
Further, in the present embodiment, when the discharge portion D[m] is driven by the supply driving signal Vin[m] having the waveform PS, the waveform PS is determined such that the ink is not discharged from the discharge portion D[m].
In the present embodiment, a portion of the waveform PS, which corresponds to the control period TSS1, is an example of an “inspection waveform”, the period T1 is an example of a “first period”, the period T2 is an example of a “second period”, the control period TSS2 is an example of a “detection period”, the potential VS1 is an example of a “first potential”, and the potential VS2 is an example of a “second potential”.
As shown in
Further, as shown in
Further, as shown in
Further, as shown in
As shown in
As described above, the detection circuit 33 generates the residual vibration signal Vd[m] based on the detection potential signal Vout[m]. In detail, the detection circuit 33 amplifies the detection potential signal Vout[m] and removes noise components to generate the residual vibration signal Vd[m] shaped into a waveform suitable for processing in the estimation unit JU.
An outline of an operation of the estimation unit JU will be described with reference to
Hereinafter, a time when the potential of the residual vibration signal Vd[m] coincides with a j-th potential VC is referred to as a time ts-j. Here, a variable j is a natural number satisfying “j≥1”.
The time specifying circuit 61 compares the potential of the residual vibration signal Vd[m] with the potential VC at an amplitude center level of the residual vibration signal Vd[m] to specify the initial time TK[m] from a time tst when the control period TSS2 starts to a time ts-K based on a result of the comparison. Then, the time specifying circuit 61 outputs the time information NTC indicating the specified initial time TK[m]. Here, a constant K is a natural number satisfying “K≥1”. In the present embodiment, the time tst is an example of a “starting time”, and the time ts-K is an example of a “reference time”.
In the present embodiment, a case where “K=3” is assumed as an example. That is, when a time from the time tst to a time ts-1 is referred to as an initial feature time Tini[m], and a time from the time ts-j to a time ts-(j+1) is referred to as a feature time TCj [m], the initial time TK[m] according to the present embodiment is expressed by Equation (1).
TK[m]=Tini[m]+TC1[m]+TC2[m] (1)
However, the initial time TK[m] shown in Equation (1) is an example, and any one of Equations (2) to (4) may be adopted as the initial time TK[m]. That is, the initial time TK[m] may be at least a time determined based on the initial feature time Tini[m].
TK[m]=Tini[m] (2)
TK[m]=Tini[m]+TC1[m] (3)
TK[m]=Tini[m]+{TC1[m]+ . . . +TC(K−1)[m]} (4)
A total time of a feature time TCj [m] and a feature time TC(j+1) [m] corresponds to a period of the residual vibration occurring in the discharge portion D[m]. Hereinafter, the period of the residual vibration occurring in the discharge portion D[m] may be referred to as a period TCS [m].
In general, the period TCS[m] of the residual vibration occurring in the discharge portion D[m] driven as the estimation target discharge portion D-S varies according to the viscosity of the ink filled in the cavity 322 of the discharge portion D[m]. In detail, when the viscosity of the ink filled in the cavity 322 of the discharge portion D[m] is high, the period TCS[m] is longer, as compared to a case where the viscosity is low. Then, the initial time TK[m] and the feature time TCj [m] are times determined according to the period TCS[m]. Therefore, when the viscosity of the ink filled in the cavity 322 of the discharge portion D[m] is high, the initial time TK[m] and the feature time TCj [m] are longer, as compared to a case where the viscosity is low.
Further, the period TCS[m] of the residual vibration occurring in the discharge portion D[m] varies according to a weight of the ink filled in the discharge portion D[m]. In detail, when the weight of the ink filled in the discharge portion D[m] is large, the period TCS[m] becomes longer, as compared to a case where the weight is small. In particular, the period TCS[m] is easily affected by the weight of the ink existing near the nozzle N among the ink filled in the discharge portion D[m].
In general, an area of a cut surface of the nozzle channel CN when the nozzle channel CN is cut in a plane that is perpendicular to the Z axis direction is smaller than an area of a cut surface of the cavity 322 when the cavity 322 is cut in a plane that is perpendicular to the Z axis direction. That is, flow channel resistance of the nozzle channel CN is larger than flow channel resistance of the cavity 322. Therefore, even when the weight of the ink filled in the discharge portion D[m] is the same, the period TCS[m] varies according to the intra-channel ink mass Mn. In detail, when the intra-channel ink mass Mn is large, the period TCS[m] becomes longer, as compared to a case where the intra-channel ink mass Mn is small. That is, when the intra-channel ink mass Mn is large, the initial time TK[m] and the feature time TCj [m] become longer, as compared to a case where the intra-channel ink mass Mn is small.
As described above, in the present embodiment, in the period Tp1, the ink filled in the discharge portion D[m] driven as the estimation target discharge portion D-S is drawn in the +Z direction. In other words, in the period TpL, the meniscus distance dZ increases. Then, when the viscosity of the ink filled in the discharge portion D[m] is low, the drawing amount of the ink in the period Tp1 becomes large, as compared to a case where the viscosity is high. That is, as shown in
Further, as described above, in the present embodiment, the supply driving signal Vin[m] having the waveform PS, which is supplied to the discharge portion D[m] driven as the estimation target discharge portion D-S, is maintained at the potential VS2 in the period T2 and the control period TSS2. Therefore, in the control period TSS2, the normal-time meniscus distance dZ-V and the viscosity-increasing-time meniscus distance dZ-W decrease over time, and for example, converge to substantially the same distance at a termination time of the control period TSS2. In other words, the differential value ΔdZ decreases over time in the control period TSS2.
When the meniscus distance dZ is large, the intra-channel ink mass Mn becomes small, as compared to a case where the meniscus distance dZ is small. Then, when the intra-channel ink mass Mn is small, the period TCS[m] becomes short, as compared to a case where the intra-channel ink mass Mn is large. That is, when an elapsed time from the start time tst of the control period TSS2 is short, the differential value Δdz becomes large and the differential value ΔTCS also becomes large, as compared to a case where the elapsed time is long. In other words, as the elapsed time from the start time tst of the control period TSS2 becomes shorter, a viscosity increasing degree of the ink filled in the discharge portion D[m] driven as the estimation target discharge portion D-S can be reflected on the period TCS[m] with high accuracy. Therefore, the initial feature time Tini[m] is a value on which the viscosity increasing degree of the ink filled in the discharge portion D[m] is reflected with high accuracy, as compared to the feature time TCj [m]. That is, since the initial time TK[m] according to the present embodiment includes the initial feature time Tini[m], the initial time TK[m] can be set to a value on which the viscosity increasing degree of the ink filled in the discharge portion D[m] is reflected with high accuracy, as compared to a case where the initial time TK[m] does not include the initial feature time Tini[m].
The viscosity estimating circuit 62 estimates the viscosity of the ink filled in the discharge portion D[m] driven as the estimation target discharge portion D-S, based on the initial time TK[m] indicated by the time information NTC output from the time specifying circuit 61 and viscosity calculating information NSJ. Here, the viscosity calculating information NSJ, which is an example of “correspondence information”, is information indicating a relationship between the initial time TK[m] and the viscosity of the ink filled in the discharge portion D[m]. In detail, the viscosity calculating information NSJ may be information indicating a coefficient of an equation obtained by linearly approximating a relationship between the viscosity of the ink filled in the discharge portion D[m] and the initial time TK[m], using the initial time TK[m] specified by filling the discharge portion D[m] with one ink having a known viscosity and driving the discharge portion D[m] as the estimation target discharge portion D-S and the initial time TK[m] specified by filling the discharge portion D[m] with another ink having a known viscosity that is different from the viscosity of the one ink and driving the discharge portion D[m] as the estimation target discharge portion D-S.
When estimating the viscosity of the ink filled in the discharge portion D[m] driven as the estimation target discharge portion D-S, the viscosity estimating circuit 62 outputs the viscosity information NND indicating a result of the estimation.
When outputting the printing signal SI designating that the discharge portion D[m] is driven as the estimation target discharge portion D-S, the control unit 2 stores the viscosity information NND obtained by the viscosity estimating circuit 62 in the storage unit 5, in association with the number “m” of the discharge portion D[m]. The control unit 2 may determine whether or not to perform cleaning for discharging the ink from the discharge portion D[m], based on the viscosity information NND, and may change the waveform of the driving signal Com to a waveform suitable for the viscosity of the ink filled in the discharge portion D[m].
As described above, in the present embodiment, the viscosity of the ink filled in the discharge portion D[m] is estimated based on the initial time TK[m] including the initial feature time Tini[m]. The initial feature time Tini [m] and the feature time TCj [m] are determined according to the period TCS[m] of the residual vibration occurring in the discharge portion D[m], and are not affected by the amplitude of the residual vibration. Therefore, according to the present embodiment, even when the amplitude of the residual vibration occurring in the discharge portion D[m] varies since noise is superimposed on the supply driving signal Vin[m] that is the driving signal Com supplied to the discharge portion D[m], the viscosity of the ink filled in the discharge portion D[m] can be estimated with high accuracy.
Further, in the present embodiment, the viscosity of the ink filled in the discharge portion D[m] is estimated based on the initial time TK[m] including the initial feature time Tini[m] starting from the time tst at which the control period TSS2 starts. That is, according to the present embodiment, the viscosity of the ink filled in the discharge portion D[m] is estimated based on the initial time TK[m] including the initial feature time Tini[m] detected in a period in which the differential value ΔTCS is relatively large among the control period TSS2. Therefore, according to the present embodiment, for example, as compared to a case where the viscosity of the ink filled in the discharge portion D[m] is estimated based on only the feature time TCj [m] after the initial feature time Tini[m] among the control period TSS2, accuracy of the estimation can be improved.
The above embodiments may be variously modified. Detailed aspects of modification examples will be described below. Two or more aspects selected from the following description in a predetermined manner may be appropriately combined with each other within a range in which the aspects are not contradictory to each other. In the following modification example, an element having an effect or a function that is the same as that of the embodiment is designated by the above-described reference numeral, and detailed description thereof will be omitted.
In the above-described embodiment, the driving signal Com-B supplied to the estimation target discharge portion D-S has the waveform PS in which, in the period Tp1, the cavity 322 of the estimation target discharge portion D-S is enlarged and the ink in the estimation target discharge portion D-S is drawn in the +Z direction. However, the present disclosure may not be limited to such an aspect. The driving signal Com-B supplied to the estimation target discharge portion D-S may have a waveform in which, in the period Tp1, the ink in the estimation target discharge portion D-S is pushed out and discharged in the −Z direction.
Further, as described above, in the present modification example, the waveform PSZ is maintained at the potential VS4 in the period T2 and the control period TSS2. Therefore, in the control period TSS2, the normal-time meniscus distance dZ-V and the viscosity-increasing-time meniscus distance dz-W decrease over time, and for example, converge to substantially the same distance at the termination time of the control period TSS2. In other words, in the control period TSS2, the differential value ΔdZ between the normal-time meniscus distance dZ-V and the viscosity-increasing-time meniscus distance dZ-W decrease over time, and the differential value ΔTCS also decreases over time. Thus, even in the present modification example, as an elapsed time from the time tst when the control period TSS2 starts is shorter, a viscosity increasing degree of the ink filled in the estimation target discharge portion D-S can be reflected on the period TCS[m] with high accuracy. Thus, the initial feature time Tini[m] is a value on which the viscosity increasing degree of the ink filled in the discharge portion D[m] is reflected with high accuracy, as compared to the feature time TCj [m]. Thus, even in the present modification example, since the initial time TK[m] includes the initial feature time Tini[m], the initial time TK[m] may be a value on which the viscosity increasing degree of the ink filled in the discharge portion D[m] is reflected with high accuracy, as compared to a case where the initial time TK[m] does not include the initial feature time Tini [m].
In the above-described embodiment and the modification example 1, it is assumed that when the potential of the supply driving signal Vin[m] supplied to the discharge portion D[m] is high, the volume of the cavity 322 of the discharge portion D[m] becomes small, as compared to a case where the potential is low. However, the present disclosure is not limited to such an aspect. In the discharge portion D[m], when the potential of the supply driving signal Vin[m] supplied to the discharge portion D[m] is low, the piezoelectric element PZ[m] may be provided such that the volume of the cavity 322 of the discharge portion D[m] becomes small, as compared to a case where the potential is high.
Thus, the waveform PS according to the embodiment may be any waveform as long as the volume of the cavity 322 of the discharge portion D[m] in the period T2 becomes larger than the volume of the cavity 322 of the discharge portion D[m] in the period T1, and accordingly, the ink in the discharge portion D[m] in the period Tp1 is drawn in the +Z direction. In detail, when the potential of the supply driving signal Vin[m] supplied to the discharge portion D[m] is high, the waveform PS may be determined such that when the volume of the cavity 322 of the discharge portion D[m] becomes large, the potential VS1 in the period T1 is lower than the potential VS2 in the period T2, as compared to a case where the potential is low.
Further, the waveform PSZ according to the modification example 1 may be any waveform as long as the volume of the cavity 322 of the discharge portion D[m] in the period T2 is smaller than the volume of the cavity 322 of the discharge portion D[m] in the period T1, and accordingly, the ink in the discharge portion D[m] is pushed out in the −Z direction in the period Tp1. In detail, when the potential of the supply driving signal Vin[m] supplied to the discharge portion D[m] is high, the waveform PSZ may be determined such that when the volume of the cavity 322 of the discharge portion D[m] becomes large, the potential VS3 in the period T1 is higher than the potential VS4 in the period T2, as compared to a case where the potential is low.
In the above-described embodiment and the modification examples 1 and 2, the estimation unit JU is provided as a circuit separate from the control unit 2. However, the present disclosure is not limited to such an aspect. A part or the entirety of the estimation unit JU may be implemented as a functional block realized as the CPU or the like of the control unit 2 operates according to a control program.
In the above-described embodiment and the modification examples 1 to 3, the ink jet printer 1 is provided such that the four head units HU correspond to the four ink cartridges 310, respectively. However, the present disclosure is not limited to such an aspect. The ink jet printer 1 may include one or more head units HU and one or more ink cartridges 310.
Further, in the above-described embodiment and the modification examples 1 to 3, the estimation unit JU corresponding to each head unit HU is provided in the ink jet printer 1. However, the present disclosure is not limited to such an aspect. In the ink jet printer 1, one estimation unit JU may be provided for a plurality of head units HU and a plurality of estimation units JU may be provided for one head unit HU.
In the above-described embodiment and the modification examples 1 to 4, a case where the ink jet printer 1 is a serial printer is illustrated. However, the present disclosure is not limited to such an aspect. The ink jet printer 1 may be a so-called line printer in which the plurality of nozzles N are provided in the head module 3 to extend wider than the width of the recording paper sheet P.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-177075 | Sep 2018 | JP | national |
