JP3620722B2 - Natural period measuring device and measuring method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a nozzle opening, a pressure generation chamber that communicates with the nozzle opening and can store a liquid, a liquid supply passage that supplies the liquid to the pressure generation chamber, a liquid drop from the nozzle opening by deforming the pressure generation chamber. The present invention relates to a natural period measuring device for a liquid in a pressure generating chamber provided for a head member having a piezoelectric member to be discharged.
[0002]
[Prior art]
Nozzle opening, pressure generating chamber communicating with nozzle opening and accommodating liquid, liquid supply path for supplying liquid to pressure generating chamber, piezoelectric member for deforming pressure generating chamber and discharging liquid droplets from nozzle opening Are used for various applications.
[0003]
For example, a head member that ejects ink droplets as liquid droplets is used for recording on recording paper or the like as a recording head of an ink jet recording apparatus.
[0004]
In such a head member, measuring the natural period of the liquid in the pressure generating chamber is effective for performing liquid droplet ejection control with higher accuracy.
[0005]
However, an apparatus for measuring the natural period of the liquid in the pressure generation chamber with sufficiently high accuracy has not yet been realized.
[0006]
[Problems to be solved by the invention]
The present invention has been made in consideration of such points, and an object of the present invention is to provide a natural period measurement device that measures the natural period of a liquid in a pressure generating chamber with sufficiently high accuracy, particularly at extremely high speed. And
[0007]
[Means for Solving the Problems]
The present invention relates to a nozzle opening, a pressure generation chamber that communicates with the nozzle opening and can store a liquid, a liquid supply passage that supplies the liquid to the pressure generation chamber, a liquid drop from the nozzle opening by deforming the pressure generation chamber. An apparatus for measuring a natural period of a liquid in a pressure generating chamber provided for a head member having a piezoelectric member to be ejected, a driving means for supplying a plurality of types of driving signals to the piezoelectric member, and a nozzle opening by each driving signal Pressure information measurement means for measuring information on the speed of each liquid droplet ejected from the liquid, and pressure generation based on the mutual relationship between the information on the speed of the liquid droplets obtained by a plurality of types of drive signals and the speed information measurement means Determining whether or not the difference between the natural period derived by the arithmetic unit for deriving the natural period of the indoor liquid and the design natural period predicted in advance is within a predetermined range A signal correcting unit that controls the driving unit to correct a plurality of types of driving signals supplied from the driving unit to the piezoelectric member when the difference is determined by the separate unit and the determining unit to exceed the predetermined range. And a natural period measuring device.
[0008]
According to the present invention, the calculation unit derives the natural period of the liquid in the pressure generating chamber based on the correlation between the plurality of types of drive signals and information on the speed of the liquid droplets obtained by the speed information measuring unit. The natural period of the liquid in the pressure generating chamber can be obtained with sufficiently high accuracy.
[0009]
Further, according to the present invention, for example, when the ejected liquid droplet has a satellite droplet in addition to the main droplet, and the natural period cannot be accurately measured due to the influence of the satellite droplet (at this time, The difference between the derived natural period and the design natural period predicted in advance exceeds a predetermined range), multiple types of drive signals supplied to the piezoelectric member are corrected, and information on the velocity of each liquid droplet is measured again Thus, the natural period of the liquid in the pressure generating chamber can be derived again. Therefore, the natural period of the liquid in the pressure generating chamber can be obtained with sufficiently high accuracy by eliminating the influence of satellite droplets.
[0010]
The present inventor has found that in order to effectively eliminate the influence of satellite droplets, it is preferable to modify a plurality of types of drive signals by lowering the drive voltage of the drive signals.
[0011]
Preferably, the speed information measuring means receives the light after crossing the liquid drop passage space, and a light emitting unit that emits light in a trajectory that crosses the liquid drop passage space from the nozzle opening. Information on the velocity of the liquid droplets ejected from the nozzle openings, specifically the velocity of the liquid droplets and the liquid droplets based on the timing of driving the piezoelectric member by the driving unit and the light receiving state of the light receiving portion And a speed information calculation unit for deriving the time until the light is blocked.
[0012]
The light emitting unit has, for example, a semiconductor laser. In addition, the light receiving unit includes, for example, a photodiode.
[0013]
As described above, when it is determined that the liquid droplet passes through the optical trajectory and the information regarding the velocity of the liquid droplet is measured, the information regarding the velocity of the liquid droplet can be accurately measured in a very short time.
[0014]
Specifically, for example, the plurality of types of drive signals supplied to the piezoelectric member by the drive means include a first ramp voltage unit that supplies the piezoelectric member with a voltage gradient that expands the pressure generation chamber and depressurizes the inside. A first voltage maintaining unit that supplies a voltage that maintains the reduced pressure state to the piezoelectric member; a second ramp voltage unit that supplies the piezoelectric member with a voltage gradient that contracts the pressure generation chamber and pressurizes the interior; And differ from each other in the duration of the first voltage maintaining unit.
[0015]
Alternatively, the plurality of types of drive signals supplied to the piezoelectric member by the drive means maintain the reduced pressure state with the first ramp voltage unit that supplies the piezoelectric member with a voltage gradient that expands the pressure generation chamber and depressurizes the inside. A first voltage maintaining unit that supplies such a voltage to the piezoelectric member, a second gradient voltage unit that supplies a voltage gradient to the piezoelectric member so as to pressurize the interior by contracting the pressure generation chamber, A second voltage maintaining unit that supplies the piezoelectric member with a voltage that maintains the voltage, and a third ramp voltage unit that supplies the piezoelectric member with a voltage gradient that returns the pressure generating chamber to the original state; The durations of the first voltage maintaining units are different from each other.
[0016]
In these cases, it is preferable that the signal correction unit corrects a plurality of types of drive signals by lowering the voltage value supplied by the first voltage maintaining unit.
[0017]
In addition, the durations of the first voltage maintaining units of the plurality of drive signals are selected so that at least two minimum values can be specified for the duration of the information related to the velocity of the liquid droplets obtained by the velocity information measuring unit. It is preferable.
[0018]
In this case, it is preferable that the calculation unit outputs a difference in duration between the two first voltage maintaining units corresponding to the two minimum values as a natural period of the liquid in the pressure generating chamber.
[0019]
The liquid is, for example, ink containing a color material for drawing an image on recording paper.
[0020]
Alternatively, the present invention provides a nozzle opening, a pressure generation chamber that communicates with the nozzle opening and can store a liquid, a liquid supply passage that supplies the liquid to the pressure generation chamber, and the pressure generation chamber by deforming the liquid from the nozzle opening. A method of measuring a natural period of a liquid in a pressure generating chamber with respect to a head member having a piezoelectric member that discharges droplets, the step of supplying a plurality of types of drive signals to the piezoelectric member, and each drive signal Based on the correlation between the step of measuring information about the velocity of each liquid droplet ejected from the nozzle opening and the information on the velocity of the liquid droplets measured with multiple types of drive signals, the natural period of the liquid in the pressure generation chamber Determining the difference between the derived natural period and the design natural period predicted in advance within a predetermined range, and determining that the difference exceeds the predetermined range. A step of correcting a plurality of types of drive signals supplied to the piezoelectric member, a step of measuring again information relating to the velocity of each liquid droplet ejected from the nozzle opening by the corrected drive signals, and a correction A step of deriving the natural period of the liquid in the pressure generation chamber again based on the correlation between the plurality of types of drive signals and the information on the velocity of the liquid droplet measured again. This is a method of measuring the period.
[0021]
Preferably, the step of correcting the plurality of types of drive signals is a step of correcting the plurality of types of drive signals by lowering the drive voltage of the drive signal.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0023]
FIG. 1 is a schematic block diagram showing a natural period measuring device according to a first embodiment of the present invention. As shown in FIG. 1, the natural period measuring device 40 of the present embodiment is provided for the head member 50.
[0024]
The head member 50 deforms the nozzle opening 51, a pressure generation chamber 52 that communicates with the nozzle opening 51 and can store liquid, a liquid supply path 54 that supplies the liquid to the pressure generation chamber 52, and the pressure generation chamber 52. And a piezoelectric member 53 that ejects liquid droplets from the nozzle openings 51. The liquid droplet is, for example, an ink droplet containing a color material for drawing an image on recording paper.
[0025]
On the other hand, the natural period measurement device 40 includes a drive circuit 41 that supplies a plurality of types of drive signals to the piezoelectric member 53, and a speed measurement device 10 that measures the speed of each liquid droplet ejected from the nozzle opening 51 by each drive signal. It is equipped with.
[0026]
The speed measurement device 10 according to the present embodiment includes a light emitting unit 12 that emits light in a trajectory L that intersects the liquid drop passage space S from the nozzle opening 51, and a liquid drop passage space S The speed at which the speed of the liquid droplet ejected from the nozzle opening 51 is derived based on the light receiving part 13 that receives light, the timing related to driving of the piezoelectric member 53 by the drive circuit 41 and the light receiving state of the light in the light receiving part 13. And an arithmetic unit 14.
[0027]
Specifically, the light emitting unit 12 includes a semiconductor laser 12a, and the light receiving unit 13 includes a photodiode 13a. The light emitted from the semiconductor laser 12a intersects the liquid droplet passage space S and is received by the photodiode 13a.
[0028]
In the present embodiment, the arrangement of the light path L, the liquid drop passage space S, and the light receiving unit 13 is such that light reception by the light receiving unit 13 is interrupted while the liquid drop passes through the liquid drop passage space S. Have been adjusted to be.
[0029]
The light receiving unit 13 outputs a pulse waveform P (see FIG. 3) having a width corresponding to the light reception interruption period through photoelectric conversion processing by the photodiode 13a.
[0030]
In the present embodiment, one or more ink mist shielding plates 20 are disposed between the light emitting unit 12 and the liquid drop passage space S and between the light receiving unit 13 and the liquid drop passage space S, respectively. Has been. Each ink mist shielding plate 20 is provided with an opening for the light path L.
[0031]
Further, in the present embodiment, as shown in FIG. 2, a high-precision for adjusting the distance between the position of the nozzle opening 51 of the head member 50 and the trajectory L of the light emitted from the light emitting unit 12. A position adjustment mechanism 30 is provided. In this case, the surface on the nozzle opening 51 side of the head member 50 is configured in parallel with the light path L, and the position adjusting mechanism 30 causes the surface on the nozzle opening 51 side to be perpendicular to the light path L. It moves relatively accurately.
[0032]
When the light trajectory L is blocked by the head member 50 by the relative movement of the head member 50 by the position adjusting mechanism 30 (the broken line state in FIG. 2), the surface on the nozzle opening 51 side coincides with the light trajectory L. It can be certified that Thereafter, the surface on the nozzle opening 51 side and the light path L can be positioned at a predetermined interval x with high accuracy by the position adjusting mechanism 30.
[0033]
As shown in FIG. 3, the drive circuit 41 of the present embodiment is in a state where a plurality of types of drive signals DS for driving the piezoelectric member 53 can be used. Each drive signal DS is sent to the piezoelectric member 53 using an appropriate latch signal LAT as a trigger.
[0034]
In this case, each drive signal DS has a first ramp voltage unit s1 that supplies a voltage gradient that expands the pressure generation chamber 52 and depressurizes the interior to the piezoelectric member 53, and a voltage that maintains the depressurized state. A first voltage maintaining unit s2 to be supplied to the piezoelectric member 53, and a second voltage supply to the piezoelectric member 53 that causes the pressure generating chamber 52 to contract and pressurize the inside, and return the pressure generating chamber 52 to its original state. And a ramp voltage part s3.
[0035]
Alternatively, as shown in FIG. 4, each drive signal DS includes a first ramp voltage unit s <b> 1 that supplies the piezoelectric member 53 with a voltage gradient that expands the pressure generation chamber 52 to depressurize the interior, and the reduced pressure state. A first voltage maintaining unit s2 that supplies a voltage to maintain the piezoelectric member 53; a second gradient voltage unit s3 that supplies the piezoelectric member 53 with a voltage gradient that contracts the pressure generating chamber 52 and pressurizes the interior; The second voltage maintaining unit s4 that supplies the piezoelectric member 53 with a voltage that maintains the pressurized state, and the third slope that supplies the piezoelectric member 53 with a voltage gradient that returns the pressure generating chamber 52 to the original state. Voltage part s5.
[0036]
3 and 4, the plurality of drive signals DS are different from each other in the duration of the first voltage maintaining unit s2. Specifically, as will be described later, the duration of the first voltage maintaining unit s2 of the plurality of drive signals DS has two local minimum values with respect to the duration of the liquid droplet obtained by the velocity measuring device 10. Selected (set) so that it can be identified.
[0037]
When the piezoelectric member 53 is driven by each drive signal DS, a liquid droplet is ejected from the nozzle opening 51. More precisely, the liquid droplet is ejected in the vicinity of the timing at which the second ramp voltage unit s3 ends (in the case of FIG. 4, the timing at which the second ramp voltage unit s3 switches to the second voltage maintaining unit s4).
[0038]
The speed calculation unit 14 derives the speed of each liquid droplet ejected from the nozzle opening 51 based on the timing related to driving of the piezoelectric member 53 by the drive circuit 41 and the rising timing of the pulse waveform. Specifically, from the timing when the second ramp voltage unit s3 ends (in the case of FIG. 4, the timing when the second ramp voltage unit s3 switches to the second voltage maintaining unit s4) to the rise timing of the pulse waveform P of the light receiving unit 13. X / t is derived as the liquid droplet velocity based on the time t and the distance x from the nozzle opening 51 to the light path L.
[0039]
In addition, the natural period measuring device 40 has a natural period of the liquid in the pressure generation chamber 52 based on the mutual relationship (see FIG. 5) between the plurality of types of drive signals DS and the speed of the liquid droplets obtained by the speed measuring means 10. Is provided.
[0040]
Specifically, the calculation unit 44 specifies two minimum values for the duration of the liquid droplet velocity obtained by the velocity measuring device 10, and maintains the two first voltages corresponding to the two minimum values. The difference in the duration of the parts is output as the natural period Tc of the liquid in the pressure generating chamber.
[0041]
The calculation unit 44 is connected to a determination unit 45 that uses a design natural period predicted in advance. The determination unit 45 calculates a difference between the natural period derived by the calculation unit 44 and the design natural period predicted in advance, and determines whether or not the difference is within a predetermined range.
[0042]
The determination unit 44 controls the drive circuit 41 to control the drive circuit 41 to supply a plurality of drive signals to the piezoelectric member 53 when the determination unit 44 determines that the difference exceeds a predetermined range. A signal correction unit 46 for correcting the DS is connected. In this case, the signal correction unit 46 sets the voltage value (drive voltage value) of the first ramp voltage unit s2 to, for example, 80% of the original voltage value in both the drive signal of FIG. 3 and the drive signal of FIG. It is designed to lower the value.
[0043]
Next, the operation of the present embodiment will be described.
[0044]
As described above, first, the state when the head member 50 is relatively moved by the position adjusting mechanism 30 and the light trajectory L is blocked by the head member 50 (the broken line state in FIG. 2) is the nozzle opening 51 side. It is recognized that the distance between the surface and the light path L is zero, and zero adjustment is performed. Thereafter, the position adjustment mechanism 30 positions the surface on the nozzle opening 51 side and the light trajectory L with high accuracy at a predetermined interval x.
[0045]
Next, light passing through the liquid drop passage space S is emitted from the light emitting unit 12. The light is continuously received by the light receiving unit 13.
[0046]
In this state, the drive circuit 41 sends the first drive signal DS to the piezoelectric member 53 using an appropriate latch signal LAT as a trigger. As a result, the piezoelectric member 53 deforms the pressure generating chamber 52 and a liquid droplet is ejected from the nozzle opening 51.
[0047]
The ejected liquid droplets block the light when passing through the liquid droplet passage space S. Thereby, the light reception by the light receiving unit 13 is interrupted, and the light receiving unit 13 outputs a pulse waveform P having a width corresponding to the interruption period.
[0048]
Then, the speed calculation unit 14 from the timing when the second ramp voltage unit s3 ends (in the case of FIG. 4, the timing when the second ramp voltage unit s3 switches to the second voltage maintaining unit s4) to the rising timing of the pulse waveform P. Based on the time t and the distance x from the nozzle opening 51 to the light path L, x / t is derived as the liquid droplet velocity.
[0049]
Subsequently, the drive circuit 41 sends the second drive signal DS to the piezoelectric member 53 using an appropriate latch signal LAT as a trigger. The second drive signal DS is a signal having a longer duration of the first voltage maintaining unit s2 than the first drive signal DS. As a result, the piezoelectric member 53 deforms the pressure generating chamber 52 and a liquid droplet is ejected from the nozzle opening 51.
[0050]
Then, the velocity of the liquid droplet ejected by the second drive signal DS is measured in the same manner as the velocity measurement of the liquid droplet ejected by the first drive signal DS.
[0051]
Subsequently, the drive circuit 41 sends a third drive signal DS to the piezoelectric member 53 using an appropriate latch signal LAT as a trigger. The third drive signal DS is a signal having a longer duration of the first voltage maintaining unit s2 than the second drive signal DS. As a result, the piezoelectric member 53 deforms the pressure generating chamber 52 and a liquid droplet is ejected from the nozzle opening 51.
[0052]
Then, the velocity of the liquid droplet ejected by the third drive signal DS is measured in the same manner as the velocity measurement of the liquid droplet ejected by the first and second drive signals DS.
[0053]
Thereafter, similarly, supply of the remaining drive signal DS to the piezoelectric member 53 and measurement of the speed of the liquid droplets ejected by each drive signal DS are sequentially performed. Since the order of the length of each drive signal DS is μs, the above steps can be performed in a very short time.
[0054]
The calculation unit 44 of the natural period measurement device 40 is based on the plurality of types of drive signals DS and the velocity of the liquid droplets obtained by the velocity measurement device 10, and the liquid droplets have the duration of the first voltage maintaining unit s 2 as the horizontal axis. Create a plot graph with the speed of An example of such a graph is shown in FIG.
[0055]
The calculation unit 44 of the natural period measurement device 40 specifies two minimum values for the duration of the liquid droplet velocity from such a plot graph, and two first voltages corresponding to the two minimum values. The difference in duration of the maintenance unit is output as the natural period Tc of the liquid in the pressure generation chamber 52.
[0056]
In general, when a liquid droplet is ejected from the nozzle opening 51 by supplying the drive signal DS having the waveform pattern shown in FIG. 4 to the piezoelectric member 53, the duration of the second voltage maintaining unit s4 is the liquid in the pressure generating chamber 52. A very good damping action can be obtained when the natural period Tc coincides. Therefore, accurately measuring the natural period Tc of the liquid in the pressure generation chamber 52 makes it possible to significantly improve the liquid droplet ejection performance from the nozzle opening 51.
[0057]
In the present embodiment, the comparison unit 45 compares the natural period Tc obtained by the calculation unit 44 with the design natural period predicted in advance. If the two values are close, it can be determined that the natural period Tc has been correctly measured. However, when the two values are significantly different, that is, when the difference between the natural period Tc and the design natural period predicted in advance exceeds a predetermined range, the natural period Tc is measured again.
[0058]
The difference may exceed a predetermined range when the liquid droplet ejected from the nozzle opening is accompanied by a presatellite droplet in addition to the main droplet. When the velocity for the presatellite droplet is measured by the velocity measuring device 10, the plot graph of FIG. 5 becomes as shown in FIG. 6, and the process of specifying two local minimum values for the duration is performed as desired. This is because it becomes difficult.
[0059]
When redoing the measurement of the natural period Tc, the signal correction unit 46 controls the drive circuit 41 to correct a plurality of drive signals DS supplied from the drive circuit 41 to the piezoelectric member 53. In this case, the signal correction unit 46 determines the voltage value (drive voltage value) of the first ramp voltage unit s2 in the case of the drive signal of FIG. 3 and the drive signal of FIG. To a value of 80%.
[0060]
By reducing the drive voltage value in this way, it is possible to suppress the generation of presatellite droplets.
[0061]
In the same manner as described above, the supply of the corrected drive signal DS to the piezoelectric member 53 and the speed measurement of the liquid droplet ejected by each drive signal DS are sequentially performed. Since the order of the length of each drive signal DS is μs, the above steps can be performed in a very short time.
[0062]
The calculation unit 44 of the natural period measurement device 40 calculates the duration of the first voltage maintaining unit s2 on the horizontal axis based on the corrected plural types of drive signals DS and the velocity of the liquid droplets obtained by the velocity measurement device 10. And re-create a plot graph with the velocity of the liquid drop as the vertical axis.
[0063]
The calculation unit 44 of the natural period measurement device 40 identifies two minimum values for the duration of the liquid droplet from such a plot graph, and two first voltages corresponding to the two minimum values. The difference in duration of the maintaining unit is output again as the natural period Tc of the liquid in the pressure generation chamber 52.
[0064]
Then, the comparison unit 45 compares the natural period Tc obtained by the calculation unit 44 with the design natural period predicted in advance again.
[0065]
The above steps are repeated until both values are close, that is, until it is determined that the difference between the natural period Tc and the design natural period predicted in advance is within a predetermined range. As a result, the natural period of the liquid in the pressure generation chamber 52 can be obtained with sufficiently high accuracy by eliminating the influence of the presatellite droplets.
[0066]
As described above, according to the present embodiment, the calculation unit 44 has the internal pressure in the pressure generation chamber 52 based on the mutual relationship between the plurality of types of drive signals DS and the velocity of the liquid droplets obtained by the velocity measuring device 10. Since the natural period of the liquid is derived, the natural period of the liquid in the pressure generation chamber 52 can be obtained with sufficiently high accuracy.
[0067]
In particular, in the present embodiment, the ejected liquid droplet has a presatellite droplet in addition to the main droplet, and the natural period Tc cannot be accurately measured due to the influence of the presatellite droplet (this When the difference between the derived natural period Tc and the design natural period predicted in advance exceeds a predetermined range), the plurality of drive signals DS supplied to the piezoelectric member 53 are corrected so that the velocity of each liquid droplet is Measurement is performed again, and the natural period Tc of the liquid in the pressure generation chamber 52 is derived again. Therefore, the natural period of the liquid in the pressure generating chamber can be obtained with sufficiently high accuracy by eliminating the influence of the presatellite droplet.
[0068]
Further, in the present embodiment, since the speed of the liquid drop is measured by determining that the liquid drop passes through the optical trajectory L, the speed of the liquid drop can be accurately measured in a very short time, As a result, the natural period of the liquid in the pressure generation chamber 52 can be measured accurately in a very short time.
[0069]
Further, in the present embodiment, since the light reception by the light receiving unit 13 is interrupted while the liquid droplet is passing through the passage space S of the liquid droplet, the passage state of the optical trajectory L of the liquid droplet is Is easily determined.
[0070]
In addition, since the ink mist shielding plate 20 is disposed between the light emitting unit 13 and the liquid drop passage space S and between the light receiving unit 14 and the liquid drop passage space S, the light emitting unit 13 and the light receiving unit 13 receive light. It is possible to avoid the ink mist from adhering to the portion 14.
[0071]
In the above embodiment, the speed calculation unit 14 receives light from the timing when the second ramp voltage unit s3 ends (in the case of FIG. 4, the timing when the second ramp voltage unit s3 switches to the second voltage maintaining unit s4). The speed of the liquid droplet is derived using the time t until the rising timing of the pulse waveform P of the unit 13. However, when high-precision positioning is possible with respect to the central axis of the light trajectory L, the timing when the second ramp voltage unit s3 ends (the timing when the second ramp voltage unit s3 switches to the second voltage maintaining unit s4). It is preferable to derive the velocity of the liquid droplet using the time t ′ (see FIG. 3) from the timing until the center timing of the pulse waveform P of the light receiving unit 13.
[0072]
In the embodiment described above, the natural period Tc of the liquid in the pressure generation chamber 52 is obtained after calculating the velocity of the liquid droplet ejected from the nozzle opening 51. However, without calculating the velocity of the liquid droplet (as a velocity dimension), for example, the timing at which the second ramp voltage unit s3 ends (in the case of FIG. 4, the second ramp voltage unit s3 is switched to the second voltage maintaining unit s4). The natural period can also be obtained directly from the time t from the timing) to the rise timing of the pulse waveform P.
[0073]
A second embodiment of the present invention configured as described above will be described with reference to FIG. As shown in FIG. 7, the natural period measurement device 40 of the present embodiment is provided with a pulse appearance time (latch pulse time) acquisition unit 114 instead of the speed calculation unit 14.
[0074]
The speed calculation unit 14 derives x / t as the liquid droplet velocity based on the time t and the distance x from the nozzle opening 51 to the light driving L, while the pulse appearance time acquisition unit 140 calculates the time t Stay on getting.
[0075]
Other configurations are substantially the same as those of the first embodiment shown in FIGS. 1 to 4, and the same parts are denoted by the same reference numerals and description thereof is omitted.
In the first place, the time t and the liquid droplet velocity are in an inversely proportional relationship, as is apparent from the relational expression. Therefore, in the case of the present embodiment, the same effect as that of the first embodiment can be obtained only by replacing the liquid droplet velocity with the time t. For example, a plot graph that can be created to determine the natural period Tc is as shown in FIG.
[0076]
【The invention's effect】
As described above, according to the present invention, the calculation unit derives the natural period of the liquid in the pressure generation chamber based on the mutual relationship between the plurality of types of drive signals and the velocity of the liquid droplets obtained by the velocity measuring means. Therefore, the natural period of the liquid in the pressure generating chamber can be obtained with sufficiently high accuracy.
[0077]
In particular, according to the present invention, for example, when the ejected liquid droplet has a satellite droplet in addition to the main droplet, and the natural period cannot be accurately measured due to the influence of the satellite droplet (at this time, The difference between the derived natural period and the design natural period predicted in advance exceeds a predetermined range), multiple types of drive signals supplied to the piezoelectric member are corrected, and information on the velocity of each liquid droplet is measured again Thus, the natural period of the liquid in the pressure generating chamber is derived again. Therefore, the natural period of the liquid in the pressure generating chamber can be obtained with sufficiently high accuracy by eliminating the influence of satellite droplets.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram of a natural period measuring device according to a first embodiment of the present invention.
FIG. 2 is a view showing a position adjusting mechanism for adjusting a distance between a head member and a light path.
FIG. 3 is a diagram illustrating a specific example of a latch signal, a drive signal, and an output pulse waveform.
FIG. 4 is a diagram illustrating another specific example of a latch signal, a drive signal, and an output pulse waveform.
FIG. 5 is a diagram illustrating an example of a plot graph in which the duration of the first voltage maintaining unit is the horizontal axis and the velocity of the liquid droplet is the vertical axis.
6 is a diagram illustrating an example of a plot graph similar to that in FIG. 5 when presatellite droplets are present. FIG.
FIG. 7 is a schematic block diagram of a natural period measuring device according to a second embodiment of the present invention.
FIG. 8 is a diagram illustrating an example of a plot graph in which the duration of the first voltage maintaining unit is the horizontal axis and the pulse appearance time is the vertical axis.
[Explanation of symbols]
10 Speed measuring device
12 Light emitting part
12a Semiconductor laser
12 '2nd light emission part
12a 'semiconductor laser
13 Light receiver
13a photodiode
13 'second light receiving part
13a 'photodiode
14 Speed calculator
20, 20 'ink mist shielding plate
30 Position adjustment mechanism
40 natural period measuring device
41 Drive circuit
44 Calculation unit
45 Comparison part
46 Signal correction section
50 Head member
51 Nozzle opening
52 Pressure generation chamber
53 Pressure generating means
54 Liquid supply path
114 Pulse appearance time acquisition unit

Claims (12)

Nozzle opening, pressure generating chamber communicating with nozzle opening and accommodating liquid, liquid supply path for supplying liquid to pressure generating chamber, piezoelectric member for deforming pressure generating chamber and discharging liquid droplets from nozzle opening A natural period measuring device for the liquid in the pressure generating chamber provided for the head member,
Drive means for supplying a plurality of types of drive signals to the piezoelectric member;
Speed information measuring means for measuring information about the speed of each liquid droplet ejected from the nozzle opening by each drive signal;
A calculation unit for deriving the natural period of the liquid in the pressure generation chamber based on the correlation between the plurality of types of drive signals and information on the velocity of the liquid droplets obtained by the velocity information measurement unit;
A discriminator for discriminating whether or not the difference between the natural period derived by the arithmetic unit and the design natural period predicted in advance is within a predetermined range;
A signal correction unit that controls the driving unit to correct a plurality of types of driving signals supplied from the driving unit to the piezoelectric member when the determination unit determines that the difference exceeds a predetermined range;
A natural period measuring device comprising: Speed information measuring means
A light emitting unit that emits light in a trajectory that intersects the passage space of the liquid droplet from the nozzle opening;
A light receiving portion for receiving light after intersecting the passage space of the liquid drop;
A speed information calculation unit for deriving information on the speed of the liquid droplet ejected from the nozzle opening based on the timing related to the driving of the piezoelectric member by the driving unit and the light receiving state of the light in the light receiving unit;
The natural period measuring device according to claim 1, wherein The natural period measuring apparatus according to claim 2, wherein the light emitting unit includes a semiconductor laser. 4. The natural period measuring device according to claim 2, wherein the light receiving unit includes a photodiode. The plurality of types of drive signals supplied to the piezoelectric member by the drive means are:
A first ramp voltage unit for supplying a voltage gradient to the piezoelectric member so as to expand the pressure generating chamber and depressurize the inside;
A first voltage maintaining unit that supplies the piezoelectric member with a voltage that maintains the reduced pressure state;
A second ramp voltage unit that supplies a voltage gradient to the piezoelectric member so as to pressurize the inside by contracting the pressure generating chamber;
Have
6. The natural period measuring device according to claim 1, wherein the durations of the first voltage maintaining units are different from each other. The plurality of types of drive signals supplied to the piezoelectric member by the drive means are:
A first ramp voltage unit for supplying a voltage gradient to the piezoelectric member so as to expand the pressure generating chamber and depressurize the inside;
A first voltage maintaining unit that supplies the piezoelectric member with a voltage that maintains the reduced pressure state;
A second ramp voltage unit that supplies a voltage gradient to the piezoelectric member so as to pressurize the inside by contracting the pressure generating chamber;
A second voltage maintaining unit that supplies the piezoelectric member with a voltage that maintains the pressurized state;
A third ramp voltage unit for supplying a voltage gradient to the piezoelectric member so as to return the pressure generating chamber to the original state;
Have
6. The natural period measuring device according to claim 1, wherein the durations of the first voltage maintaining units are different from each other. The natural period measurement according to claim 5 or 6, wherein the signal correction unit corrects a plurality of types of drive signals by lowering a voltage value supplied by the first voltage maintaining unit. apparatus. The durations of the first voltage maintaining units of the plurality of drive signals are selected so that two minimum values can be specified for the duration of the information related to the velocity of the liquid droplets obtained by the velocity information measuring means. 8. The natural period measuring device according to claim 5, wherein 9. The calculation unit is configured to output a difference in duration between the two first voltage maintaining units corresponding to the two minimum values as a natural period of the liquid in the pressure generation chamber. The natural period measuring device described in 1. The natural period measuring device according to claim 1, wherein the liquid is ink containing a color material for drawing an image on recording paper. Nozzle opening, pressure generating chamber communicating with nozzle opening and accommodating liquid, liquid supply path for supplying liquid to pressure generating chamber, piezoelectric member for deforming pressure generating chamber and discharging liquid droplets from nozzle opening And measuring the natural period of the liquid in the pressure generating chamber with respect to the head member having:
Supplying a plurality of types of drive signals to the piezoelectric member;
Measuring information about the speed of each liquid droplet ejected from the nozzle opening by each drive signal;
Deriving the natural period of the liquid in the pressure generating chamber based on the correlation between the plurality of types of driving signals and the information on the measured liquid droplet velocity;
Determining whether or not the difference between the derived natural period and the design natural period predicted in advance is within a predetermined range;
A step of correcting a plurality of types of drive signals supplied to the piezoelectric member when it is determined that the difference exceeds a predetermined range;
Measuring again the information about the speed of each liquid droplet ejected from the nozzle opening by each corrected drive signal;
A step of deriving the natural period of the liquid in the pressure generating chamber again based on the correlation between the corrected plural types of driving signals and the information on the velocity of the liquid droplet measured again. The natural period measurement method. 12. The natural period measuring method according to claim 11, wherein the step of correcting the plurality of types of drive signals is a step of correcting the plurality of types of drive signals by lowering a drive voltage of the drive signal.

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