JP2003118101A - Liquid drop jet recorder and its driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the recording time while improving the flying stability of a recording liquid by easily detecting a temperature change of the recording liquid in an actual driving state in which an operation of generating recording liquid droplets is carried out, and correctly grasping a state of a sound source. SOLUTION: An acoustic lens 6 is arranged to a bottom part of an ink storage part 2, and at the same time, a piezoelectric element 5 is set to a lower face of the acoustic lens 6. Ultrasonic waves are generated from the acoustic lens 6 by impressing a high frequency driving voltage to the piezoelectric element 5 from a driving circuit 7, which are converged to an ink level. A current flowing to the piezoelectric element 5 at this time is detected by an impedance detecting circuit 10. An impedance detection signal is supplied to an ultrasonic wave energy judging circuit 20, whereby an ink temperature is detected from a change of the impedance detection signal to a reference voltage. A heater 70 is controlled by a heater driving control circuit 71.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a droplet jet recording apparatus in which ultrasonic waves generated by a piezoelectric element are converged on the surface of a recording liquid and droplets are ejected from the surface of the recording liquid toward a recording medium. And its driving method.

[0002]

2. Description of the Related Art In this type of droplet jet recording apparatus, when ordinary ink or highly viscous ink (or wax / ink pace) is ejected as droplets, the distance between the focus liquid surface and the acoustic lens is increased. Must be accurately maintained at a distance that is an odd multiple of ¼ of the ultrasonic wavelength propagating in the ink, a high sound pressure cannot be obtained on the liquid surface, and proper droplets cannot be generated.

Here, the wavelength λ is defined by the following equation (1) according to the sound velocity C of the ink and the excitation frequency f. λ = C / f (1) The sound velocity C is defined by the following equation (2) by the bulk elastic modulus k and the ink density ρ.

C = (k / ρ) ^1/2 (2) Since the bulk modulus k changes with temperature, the sonic velocity C has temperature dependency. From the equation (2), the sonic velocity C of the ink tends to decrease as the bulk elastic modulus k decreases at high temperatures. Therefore, when the ink is heated to a high temperature to reduce the viscosity, the sound velocity also changes at the same time, so the wavelength in the ink liquid also changes depending on the ink temperature, making it impossible to maintain the proper positional relationship between the ink surface and the acoustic lens. There is a nature. Similarly, with ordinary ink, there is a problem that the generation of ink droplets becomes unstable due to changes in ink temperature.

Therefore, in the past, Japanese Patent Laid-Open No. 10-136620 has been proposed.
Japanese Laid-Open Patent Publication (hereinafter referred to as a first conventional example), Japanese Patent Laid-Open No. 10-24
No. 8447 (hereinafter, referred to as a second conventional example),
-17657 (hereinafter referred to as the third conventional example), JP-A-63-129421 (hereinafter referred to as the fourth conventional example), and US Pat. No. 4,745,419 (hereinafter referred to as the fifth conventional example). Have been proposed.

Here, in the first conventional example, the ink temperature is detected by a thermistor, and the correction is made to vary the burst number, drive voltage, and drive frequency based on the detected ink temperature. In the third conventional example, in order to keep the ink viscosity in a good state, the temperature sensor is used to detect the liquid temperature, and the ink is heated by the heater to control the ink temperature to an appropriate value. Also, the fourth conventional example and the fifth example
In the conventional example, a method is disclosed in which a variable viscosity ink or a high-temperature melting ink is positively heated by a heater, and the ink viscosity is reduced so that the energy required to generate the ink droplet is reduced and the ink droplet is ejected.

[0007]

However, in each of the above-mentioned conventional examples, the ink temperature is maintained in an appropriate state, but the initial ink viscosity may be changed due to variations in the physical properties of the ink or changes with time. There is an unsolved problem that defective generation of ink droplets may occur when the relationship between the sound velocity and the sound velocity changes.

Therefore, the present invention has been made by paying attention to the unsolved problem of the above-mentioned conventional example, in which the temperature of the recording liquid is accurately grasped and the temperature of the recording liquid is accurately ejected from the recording liquid droplets. An object of the present invention is to provide a droplet jet recording apparatus and a driving method thereof that can control the temperature to a possible temperature to improve the flight stability of recording droplets.

[0009]

In order to achieve the above object, in the liquid droplet jet recording apparatus according to the first aspect, an acoustic lens disposed on the upper surface of the piezoelectric element is disposed in the recording liquid storage portion,
A liquid droplet jet recording apparatus in which ultrasonic waves generated from the acoustic lens are converged on the surface of the recording liquid in the recording liquid container to fly recording liquid droplets by driving the piezoelectric element at a high frequency by a high frequency driving means. In the impedance detection means for detecting the impedance of the drive system for driving the piezoelectric element by the high frequency drive means, and whether or not the ultrasonic energy is appropriate based on the impedance detection signal detected by the impedance detection means. It is characterized by comprising ultrasonic energy judging means for judging and temperature controlling means for controlling the temperature of the recording liquid based on the judgment result of the ultrasonic energy judging means.

According to a second aspect of the present invention, there is provided the droplet jet recording apparatus according to the first aspect, wherein the impedance detecting means is a drive current detecting means for detecting a drive current of the piezoelectric element, and the drive current detecting means. Has a current waveform processing means for converting the drive current detected by 1. into a DC voltage change, and a comparison means for comparing the output voltage of the current waveform processing means with a reference voltage, and the impedance detection signal is output from the comparison means. It is characterized by that.

Further, in the liquid droplet jetting recording apparatus according to a third aspect of the present invention, in the invention according to the first or second aspect, the ultrasonic energy judging means detects the impedance from the driving start to the impedance change point. An energy amplification time measuring means for measuring the energy amplification time and an amplification time error calculating means for calculating an error between the energy amplification time measured by the energy amplification time measuring means and the optimum amplification time are provided. .

Furthermore, in the liquid droplet jet recording apparatus according to a fourth aspect of the present invention, in the invention according to the third aspect, the temperature control means is provided when the energy amplification time of the ultrasonic energy determination means is longer than the optimum amplification time. The recording liquid temperature is raised, and the recording liquid temperature is lowered when the amplification time is shorter than the optimum amplification time. Still further, the liquid droplet ejection recording apparatus according to claim 5 is the same as claim 3
Or the frequency control means for controlling the frequency of the high frequency drive means based on the determination result of the ultrasonic energy determination means, and the amplification time calculated by the amplification time error calculation means of the ultrasonic energy determination means. Amplification time error determination means for determining whether or not the error is within an allowable range, and when the determination result of the amplification time error determination means indicates that the amplification time error is outside the allowable range, the amplification time error is determined by the temperature control means. And selecting means for supplying the amplification time error to the frequency control means when the amplification time error is within an allowable range.

According to a sixth aspect of the present invention, there is provided the liquid drop jet recording apparatus according to the fifth aspect, wherein the frequency control means determines that the ultrasonic energy determination means determines that the energy amplification time is shorter than the optimum amplification time. Further, it is characterized in that the frequency of the high frequency drive signal of the high frequency drive means is lowered, and the control is performed such that the frequency of the high frequency drive signal of the high frequency drive means is increased when the frequency is longer than the optimum amplification time.

Further, in the liquid droplet jet recording apparatus according to a seventh aspect of the present invention, in the invention according to the first or second aspect, the ultrasonic energy judging means changes the impedance change point to the next change point based on the impedance detection signal. Liquid level amplitude time measuring means for measuring the amplitude time up to and the amplitude time error calculating means for calculating an error between the liquid level amplitude time measured by the liquid level amplitude time measuring means and the optimum amplitude time. Is characterized by.

Furthermore, in the droplet jet recording apparatus according to an eighth aspect of the present invention, in the invention according to the seventh aspect, the temperature control means is such that the liquid level amplitude time of the ultrasonic energy determination means is longer than the optimum amplitude time. It is characterized in that the recording liquid temperature is raised and the recording liquid temperature is lowered when it is shorter than the optimum amplitude time. Still further, the liquid droplet jetting recording apparatus according to a ninth aspect is the invention according to the seventh or eighth aspect, further comprising an amplitude control means for controlling the amplitude of the high frequency drive means based on the determination result of the ultrasonic energy determination means. An amplitude time error judgment means for judging whether the amplitude time error calculated by the amplitude time error calculation means of the ultrasonic energy judgment means is within an allowable range, and the judgment result of the amplitude time error judgment means is the amplitude time. And a selecting means for supplying the amplitude time error to the temperature control means when the error is outside the allowable range, and supplying the amplitude time error to the amplitude control means when the amplitude time error is within the allowable range. It is characterized by that.

Further, in the droplet jet recording apparatus according to the tenth aspect of the present invention, in the invention according to the ninth aspect, the amplitude control means, when the determination result of the ultrasonic energy determination means is shorter than the optimum amplitude time. It is characterized in that control is performed such that the drive voltage of the high frequency drive means is increased and the drive voltage of the high frequency drive means is decreased when the drive time is longer than the optimum time.

Further, in the liquid droplet jet recording apparatus according to an eleventh aspect of the present invention, in the invention according to the first or second aspect, the ultrasonic energy judging means detects the impedance from a drive start to a change point of the impedance. A first judging means having an energy amplification time measuring means for measuring the energy amplification time, and an amplification time error calculating means for calculating an error between the energy amplification time measured by the energy amplification time measuring means and the optimum amplification time; Of the liquid surface amplitude time measuring means for measuring the amplitude time from the change point of impedance to the next change point based on the impedance detection signal, and the liquid surface amplitude time and the optimum amplitude time measured by the liquid surface amplitude time measuring means Second judgment means having an amplitude time error calculation means for calculating an error, wherein the drive control means determines the judgment of the first judgment means. When the result is that the energy amplification time is shorter than the optimum amplification time, the frequency of the high frequency drive signal of the high frequency drive means is lowered, and when the result is longer than the optimum amplification time, the frequency of the high frequency drive signal of the high frequency drive means is increased. Means and the determination result of the second determining means increases the drive voltage of the high frequency drive means when the liquid level amplitude time is shorter than the optimum amplitude time, and lowers the drive voltage of the high frequency drive means when the liquid level amplitude time is longer than the optimum time. Amplitude control means for performing control, and when the amplitude time error is out of the allowable range, the amplitude time error is supplied to the temperature control means, the amplitude time error is within the allowable range, and the amplification is performed. When the time error is outside the allowable range, the amplification error time is supplied to the frequency control means, and when the amplification time error is within the allowable range, the amplitude time error is adjusted. It is characterized in that it comprises a selection means for supplying the width control means.

Further, according to a twelfth aspect of the present invention, in a method of driving a droplet jet recording apparatus, an acoustic lens disposed on the upper surface of a piezoelectric element is disposed in a recording liquid storage section, and the piezoelectric element is driven to a high frequency by high frequency driving means. The driving method of a droplet jet recording apparatus, wherein the ultrasonic waves generated from the acoustic lens are converged on the surface of the recording liquid in the recording liquid container to fly recording droplets by driving, and the high frequency driving means is used. Driving the piezoelectric element, detecting the impedance of the drive system including the piezoelectric element in the driving state of the piezoelectric element, and determining whether or not the ultrasonic energy is appropriate based on the detected impedance And a step of controlling the temperature of the recording liquid based on the result of the determination as to whether or not the ultrasonic energy is appropriate.

Still further, in the driving method of the liquid droplet jetting recording apparatus according to the thirteenth aspect, the acoustic lens disposed on the upper surface of the piezoelectric element is disposed in the recording liquid storage portion, and the piezoelectric element is driven to a high frequency by a high frequency driving means. The driving method of a droplet jet recording apparatus, wherein the ultrasonic waves generated from the acoustic lens are converged on the surface of the recording liquid in the recording liquid container to fly recording droplets by driving, and the high frequency driving means is used. Driving the piezoelectric element, detecting the impedance of the drive system including the piezoelectric element in the driving state of the piezoelectric element, and determining whether or not the ultrasonic energy is appropriate based on the detected impedance And the step of controlling the recording liquid temperature when the energy of the ultrasonic wave is not appropriate as a result of the judgment of the step, and the control of the recording liquid temperature. After the wave energy becomes proper state, it is characterized by repeatedly performing a step of controlling the frequency of the high frequency drive unit based on the determination result whether ultrasound energy is appropriate.

According to a fourteenth aspect of the present invention, there is provided a method of driving a droplet jet recording apparatus, wherein an acoustic lens disposed on an upper surface of a piezoelectric element is disposed in a recording liquid storage section, and the piezoelectric element is driven at a high frequency by a high frequency drive means. In the driving method of the droplet jet recording apparatus, the ultrasonic wave generated from the acoustic lens is converged on the surface of the recording liquid in the recording liquid container to cause the recording droplet to fly. Driving the piezoelectric element, detecting the impedance of the drive system including the piezoelectric element in the drive state of the piezoelectric element, and measuring the impedance change time from the start of driving to the impedance change point based on the detected impedance Then, based on the impedance change time, the positional relationship between the liquid surface at the driving focal length and the sound pressure is appropriate, and the liquid surface between the recording liquid and the acoustic lens is The temperature of the recording liquid is determined based on the step of determining whether the ultrasonic energy is properly accumulated and amplified by the standing wave in the recording liquid that is generated, and the determination result of whether the ultrasonic energy is appropriate. And a step of controlling.

Further, according to the driving method of the droplet jet recording apparatus of the fifteenth aspect, the acoustic lens disposed on the upper surface of the piezoelectric element is disposed in the recording liquid storage section, and the piezoelectric element is driven at a high frequency by the high frequency drive means. In the driving method of the droplet jet recording apparatus, the ultrasonic wave generated from the acoustic lens is converged on the surface of the recording liquid in the recording liquid container to cause the recording droplet to fly. The piezoelectric element is driven to detect the impedance of the drive system including the piezoelectric element, the energy amplification time from the start of driving to the impedance change point is measured based on the detected impedance, and driving is performed based on the energy amplification time. The positional relationship between the liquid surface at the focal length and the sound pressure is appropriate, and the ultrasonic energy is appropriate due to the standing waves in the recording liquid generated between the recording liquid surface and the acoustic lens. And ultrasonic energy determination step of determining whether the accumulated-amplification, a temperature control step of controlling recording liquid temperature when the ultrasonic energy determination step of determining results energy ultrasound is not proper,
After the ultrasonic energy is brought into a proper state by controlling the temperature of the recording liquid in the temperature control step, the ultrasonic energy determination step is executed again and the high frequency is determined based on the determination result of whether the ultrasonic energy is proper or not. And a frequency control step for controlling the frequency of the driving means are repeatedly executed.

According to a sixteenth aspect of the present invention, there is provided a method of driving a droplet jet recording apparatus, wherein an acoustic lens disposed on the upper surface of a piezoelectric element is disposed in a recording liquid storage section, and the piezoelectric element is driven by a high frequency drive means to a high frequency. The driving method of a droplet jet recording apparatus, wherein the ultrasonic waves generated from the acoustic lens are converged on the surface of the recording liquid in the recording liquid container to fly recording droplets by driving, and the high frequency driving means is used. And driving the piezoelectric element, detecting the impedance of the drive system including the piezoelectric element in the driving state of the piezoelectric element, measuring the amplitude time from the impedance change point to the next change point, and recording liquid. Whether the ultrasonic energy is properly accumulated and amplified by the standing wave in the recording liquid generated between the liquid surface of the recording liquid and the acoustic lens. And step is characterized by comprising a step of controlling the temperature of the recording liquid based on the determination result whether the energy of the ultrasonic is appropriate.

Still further, in a method of driving a droplet jet recording apparatus according to a seventeenth aspect, an acoustic lens disposed on the upper surface of the piezoelectric element is disposed in the recording liquid storage portion, and the piezoelectric element is driven by a high frequency drive means to a high frequency. The driving method of a droplet jet recording apparatus, wherein the ultrasonic waves generated from the acoustic lens are converged on the surface of the recording liquid in the recording liquid container to fly recording droplets by driving, and the high frequency driving means is used. To drive the piezoelectric element to detect the impedance of the drive system including the piezoelectric element, measure the amplitude time from the change point of the impedance to the next change point based on the detected impedance, and confirm that the viscosity of the recording liquid is appropriate. Ultrasonic energy to determine whether or not ultrasonic energy is properly accumulated and amplified by the standing waves in the recording liquid generated between the liquid surface of the recording liquid and the acoustic lens. A judgment step, a temperature control step of controlling recording liquid temperature when the ultrasonic energy determination step of determining results energy ultrasound is not proper,
After the ultrasonic energy is brought into a proper state by controlling the temperature of the recording liquid in the temperature control step, the ultrasonic energy determination step is executed again and the high frequency is determined based on the determination result of whether the ultrasonic energy is proper or not. And an amplitude control step of controlling the amplitude of the drive means are repeatedly executed.

According to the eighteenth aspect of the present invention, there is provided a method of driving a droplet jet recording apparatus, wherein an acoustic lens disposed on the upper surface of a piezoelectric element is disposed in a recording liquid storage section, and the piezoelectric element is driven at a high frequency by a high frequency drive means. In the driving method of the droplet jet recording apparatus, the ultrasonic wave generated from the acoustic lens is converged on the surface of the recording liquid in the recording liquid container to fly the recording droplets. The piezoelectric element is driven, the impedance of the drive system including the piezoelectric element is detected, the amplitude time from the detected change point of the impedance to the next change point is measured, and the viscosity of the recording liquid is appropriate. An ultrasonic energy determination step for determining viscosity for determining whether or not the ultrasonic energy is properly accumulated and amplified by the standing wave in the recording liquid generated between the surface and the acoustic lens; The temperature control step for controlling the temperature of the recording liquid when the ultrasonic wave energy is not appropriate as the result of the step determination, and the high frequency drive is performed after the ultrasonic energy has become a proper state by controlling the recording liquid temperature in the temperature control step. Means for driving the piezoelectric element to detect the impedance of a drive system including the piezoelectric element, measure the energy amplification time from the start of driving to the impedance change point based on the detected impedance, and based on the energy amplification time Whether the ultrasonic wave energy is properly accumulated and amplified by the standing wave in the recording liquid generated between the liquid surface of the recording liquid and the acoustic lens. For determining the ultrasonic energy for liquid surface position and the high frequency based on the determination result of whether the ultrasonic energy in the step is proper or not. After the frequency control step of controlling the frequency of the driving means and the ultrasonic energy becomes a proper state by controlling the frequency, the ultrasonic energy determination step for viscosity is executed again to determine whether the ultrasonic energy is proper. It is characterized in that an amplitude control step of controlling the amplitude of the high frequency drive means is repeatedly executed based on the result of the judgment.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention. In the drawing, reference numeral 1 denotes a droplet jet recording apparatus, and a case body 4 in which an ink containing portion 2 containing ink as a recording liquid is formed inside and a nozzle 3 for ejecting ink droplets is formed on an upper surface, An acoustic lens 6 for converging the ultrasonic waves generated by the piezoelectric element 5 arranged at the bottom of the ink containing section 2 in the case body 4 to the ink liquid surface at the nozzle 3 position, and a high frequency drive voltage is applied to the piezoelectric element 5. A driving circuit 7 for driving the piezoelectric element 5 at a high frequency, an impedance detecting circuit 10 for detecting impedance from the driving state of the piezoelectric element 5 by the driving circuit 7, and an ultrasonic wave based on the impedance detected by the impedance detecting circuit 10. An ultrasonic energy judgment circuit 20 for judging whether or not the energy is properly accumulated / amplified, and a judgment result of the ultrasonic energy judgment circuit 20. The drive control circuit 40 for controlling the frequency of the high frequency drive voltage generated by the drive circuit 7, the heater 70 disposed near the acoustic lens 6, and the heater 70 based on the determination result of the ultrasonic energy determination circuit 20. Heater drive control circuit 7 for drive control
1 and. Here, the heater 70 and the heater drive control circuit 71 constitute a temperature control means.

As shown in FIG. 2, the impedance detection circuit 10 has a piezoelectric element 5 whose one end is supplied with a high-frequency drive voltage from the drive circuit 7 and the other end of which is grounded via a shunt resistor Rs. The current waveform processing circuit 11 is supplied with a current change representing a change in the load impedance seen from the piezoelectric element 5 side when the liquid surface rises in the process of the ink droplet detected at the connection point with the resistance Rs flying. The current waveform processing circuit 11 includes an amplifier 12 and the amplifier 1.
The full-wave rectifier 13 performs full-wave rectification on the amplified output of No. 2, and the filter 14 that filters the rectified output of the full-wave rectifier 13 to extract the envelope of the rectified output.

The waveform processing signal output from the current waveform processing circuit 11 is supplied to one input side of the comparator 15, and the other input side of the comparator 15 is connected to the oscillation setting voltage input terminal t1 and ground. Voltage dividing resistors R1 and R interposed between
The reference voltage Vref output from the reference voltage generator 16 composed of 2 is supplied, and when the waveform processing signal Sp from this comparator 15 is below the reference voltage Vref, it is turned on and conversely. When the voltage exceeds the reference voltage Vref, a comparison signal that is turned off is output to the ultrasonic energy determination circuit 20 as the impedance detection signal Si.

As shown in FIG. 3, the ultrasonic energy determination circuit 9 receives the impedance detection signal Si output from the comparator 15 of the impedance detection circuit 10 as a D input.
Circuit 21 composed of a flip-flop circuit
AND gate to which the latch output output from the negative output terminal Q'of the latch circuit 21 and the inverted timing signal St 'and the clock pulse Cp input from the timing signal generator described later via the inverter 22a are input. 22, an error detection circuit 23 for detecting an error between the ink surface and the focus of the acoustic lens 6 based on the output pulse of the AND gate 22, and a timing for setting the generation time of the high frequency drive voltage generated by the drive circuit 7. A timing signal generator 28 for generating a signal St and a read permission signal generator 29 for generating a read permission signal SL based on the timing signal St generated by the timing signal generator 28.
And an edge detection circuit 30 that detects an edge of the read permission signal SL output from the read permission signal generator 29 and outputs a reset signal SR, and an amplification time error output from the error detection circuit 23 for heater drive control. It is composed of a selection circuit 31 for selecting whether to supply to the circuit 71 or the drive control circuit 40.

The error detection circuit 23 counts the output pulse of the AND gate 22 to measure the energy amplification time, the energy amplification time measurement counter 24, the count value of the energy amplification time measurement counter 24 and the amplification time storage circuit. The amplification time stored in advance in 25 is input, the amplification time error calculator 26 that calculates the amplification time error ΔTe by subtracting the amplification time from the count value, and the amplification time output from the amplification time error calculator 26 And a register 27 that holds the error ΔTe and outputs it to the drive control circuit 40.

In the selection circuit 31, as shown in FIG. 4, the amplification time error ΔTe stored in the register 27 of the error detection circuit 23 is input to the common terminal tc, and the normally closed contact tnc is connected to the drive control circuit 40. Connected to the normally open contact tn
switch circuit 32 in which o is an open terminal, and register 2
7, an absolute value circuit 33 for calculating the absolute value of the amplification time error ΔTe, and a preset allowable error value Ts1
Error tolerance value setting circuit 34 storing the
The absolute value | ΔTe | of the amplification time error ΔTe of is compared with the error allowable value Ts1 stored in the error allowable value setting circuit 34, and when | ΔTe | ≧ Ts1, the logical value “1”, | Δ
Select signal SC of logical value "0" when Te | <Ts1
And a AND gate 36 to which the selection signal SC output from the comparator 35 and the reset signal SR input from the edge detection circuit 30 are input. Then, the selection signal SC output from the comparator 35 is supplied to the switch circuit 32 and the heater drive circuit 71, and the output of the AND gate 36 is output to the drive control circuit 40 as the drive reset signal DR.

Further, the read permission signal SL output from the read permission signal generator 29 is supplied to the negative input terminal of the register 27, and the reset signal SR output from the edge detection circuit 30 is measured by the latch circuit 21 and the energy amplification time. Is supplied to the counter 24. Here, the read permission signal generator 29 is input to the D terminal to which the timing signal St output from the timing signal generator 28 is input and the D-type flip-flop to which the clock pulse Cp is input to the clock input terminal. 29a and a D-type flip-flop 29c to which an output signal output from the positive output terminal Q of the D-type flip-flop 29a is input to the D terminal, and a clock pulse Cp is input to the cook input terminal via the inverter 29b. , Flip-flop 29
and a NAND circuit 29d to which the output signal output from the positive output terminal Q of a and the output signal output from the negative output terminal Q of the flip-flop 29c are input.

The drive control circuit 40, as shown in FIG.
A proportional gain multiplier 41 that multiplies the amplification time error input from the register 27 of the ultrasonic energy determination circuit 20 by the proportional gain Gp, an integral gain multiplier 42 that multiplies the amplification time error by the integral gain Gi, and this integral gain. Multiplier 4
The output of 2 is integrated, and the integrated value is reset at the down edge where the drive reset signal DR supplied from the selection circuit 31 is inverted from the logical value “1” to the logical value “0”, and the proportional gain. An adder 44 for adding the output of the multiplier 41 and the output of the integrator 43, and an adder 46 for adding the addition output of the adder 44 to the previous value held in the previous value register 45 holding the previous value. , The current value register 4 for holding the addition output of the adder 46 as the current frequency command value
7 and a D / A converter 48 for converting the frequency command value held in the current value register 47 into an analog voltage. The analog voltage output from the D / A converter 48 is the frequency command value Vf. Is output to the drive circuit 7.

Here, the previous value register 45 is the timing signal generator 28 of the ultrasonic energy determination circuit 20 described above.
From the logical value "0" to the logical value "1", the addition output of the adder 46 is held as the previous value. Further, the present value register 47 is supplied with the reset signal SR output from the edge detection circuit 30 of the ultrasonic energy determination circuit 20, and at the down edge from the logical value "1" of the reset signal SR to the logical value "0". Adder 46
The addition output of is held as the frequency command value. In the previous value register 45, a preset initial frequency command value is set in the initial state when the droplet jet recording apparatus 1 is activated.

As shown in FIG. 3, the drive circuit 7 receives the oscillation frequency command value Vf output from the drive control circuit 40 and outputs an oscillation signal having a frequency corresponding to the oscillation frequency command value Vf to the timing signal generator 28. Is provided with a voltage control type oscillation circuit 8 which oscillates during a period in which the timing signal St supplied from is a logical value "0", and a voltage control type amplifier 9 to which the oscillation output of the voltage control type oscillation circuit 8 is input. .

As shown in FIG. 6, in the heater driving circuit 71, the amplification time error ΔTe output from the selection circuit 31 of the ultrasonic energy determination circuit 20 is the normally closed terminal tno, and the digital value “0” is the normally open contact. The switch circuits 72 respectively input to tnc, the proportional gain multiplier 73 for multiplying the switch output output from the movable contact tm of the switch circuit 72 by the proportional gain Gp, and the integral gain G for the switch output.
an integral gain multiplier 74 that multiplies i, an integrator 75 that integrates the output of the integral gain multiplier 74, an adder 76 that adds the output of the proportional gain multiplier 73 and the output of the integrator 75, and an adder The adder 78 that adds the addition output of the adder 76 to the previous value held in the previous value register 77 that holds the previous value, and the present value register 79 that holds the addition output of this adder 78 as the present frequency command value And a D / A converter 80 for converting the frequency command value held in the current value register 79 into an analog voltage.
The analog voltage output from the converter 80 is supplied to the heater 70.

Next, the operation of the above embodiment will be described. First, the principle of the present invention will be described. As shown in FIG. 7, the distance from the acoustic lens 6 to the ink surface at the position of the nozzle 3 is an odd multiple of ¼ wavelength of the standing wave in the ink liquid based on the ultrasonic waves generated from the acoustic lens 6. In this positional relationship, the ultrasonic energy is optimally propagated to the focus portion of the ink liquid surface. Here, the wavelength λ is defined by the sound velocity C of the ink and the excitation frequency f in (1) as described above, and the sound velocity C is the bulk elastic modulus k and the ink density ρ.
Is defined by the above equation (2).

Since the bulk modulus k changes with temperature, the sound velocity C has temperature dependency. The excitation frequency f also changes due to the temperature dependence of the piezoelectric element impedance. Furthermore, the ink surface also fluctuates, and there is no guarantee that the distance between the acoustic lens 6 and the ink surface is always a constant distance. If the sound velocity C or the excitation frequency f changes while the liquid surface distance is constant, the sound pressure changes with respect to the ink liquid surface as shown in FIG.

If the acoustic lens 6 and the ink liquid surface have a proper positional relationship, the ink droplets can be stably ejected within a certain fixed ultrasonic wave repetition time. At this time,
When the ultrasonic energy is accumulated and amplified in the ink liquid and ink droplets are ready to fly, the ink liquid surface rises rapidly and the sound pressure due to the standing wave up to now changes. This change in sound pressure appears as a load change in the current waveform when the piezoelectric element 5 is driven with a constant voltage. Therefore, a change in the ink liquid level can be detected as a change in impedance.

The ultrasonic energy in the ink liquid has a large difference in acoustic impedance at the boundary between the liquid surface and the air, and if water is Zw = 1500 × 10 ³ (Pa · s / m), the air Z
When the energy reflectance is calculated with a = 415 (Pa · s / m), R = (Zw−Za) ² / (Zw + Za) ² = 0.99 (3), which is over the liquid. 99.9% of the acoustic energy is stored and amplified.

When this ultrasonic energy is accumulated / amplified in an optimum state, the peak value of the alternating current waveform flowing through the piezoelectric element 5 is changed, that is, the impedance detection circuit 10 performs full-wave rectification of the alternating current and then filters it. As shown in FIG. 8, the DC-converted waveform has a certain optimum amplification time Te
At 0, load fluctuation occurs. Therefore, by measuring the time from the start of driving the piezoelectric element 5 to the occurrence of impedance change, it is possible to determine whether the wavelength in the ink liquid has an optimum positional relationship with respect to the liquid surface distance.

The cause of the wavelength change may be a change in the sound velocity C due to the ink temperature, a change in the excitation frequency f due to the temperature change of the piezoelectric element 5, and the like. It is possible to correct the sound pressure by adjusting the frequency f. Therefore, in the first embodiment, while the drive circuit 7 is applying the high frequency voltage of the excitation frequency f to the piezoelectric element 5, the impedance detection circuit 10 detects the impedance change.

This change in impedance is detected by the drive circuit 7 from the drive circuit 7 in the piezoelectric element 5 because a rise is not formed on the ink surface unless ink droplets are formed.
When a high frequency drive voltage as shown in (a) is applied,
The current waveform obtained by amplifying the drive current appearing between the piezoelectric element 5 and the shunt resistor Rs by the amplifier 12 of the current waveform processing circuit 11 has a relatively small constant amplitude as shown in FIG. When full-wave rectification is performed by the circuit 13, the full-wave rectification waveform at this time is as shown in FIG. 9B as shown in FIG.
Of the reference voltage Vref as shown in FIG. 9D.
The envelope waveform is slightly lower than.

Therefore, by supplying the filter output to the comparator 15 and comparing it with the reference voltage Vref, the impedance detection signal Si output from the comparator 15 is detected.
Keeps on as shown in FIG. 9 (e). However, when the high frequency drive voltage is continuously applied from the drive circuit 7 to the piezoelectric element 5 and the ink surface rises and ink droplets are generated, the piezoelectric element 5 and the shunt resistor Rs are separated from each other. As shown in FIG. 10B, the amplified waveform obtained by amplifying the generated drive current by the amplifier 12 changes from the amplitude at the normal time to the large amplitude, becomes smaller than the normal time, and then becomes slightly larger than the normal time. Changes in amplitude

Therefore, the full-wave rectified waveform full-wave rectified by the full-wave rectifier 13 also changes from a normal amplitude to a large amplitude and then to an amplitude smaller than the normal amplitude, as shown in FIG. 10 (c). The filter output waveform obtained by filtering this with the filter 14 exceeds the reference voltage Vref at the start of driving and then falls below the reference voltage Vref as shown in FIG. Then, the reference voltage Vref is slightly exceeded.

Therefore, the impedance detection signal Si output from the comparator 15 continues to be in the ON state at the start of driving as shown in FIG. 10 (e), but at the time when the filter output exceeds the reference voltage Vref, it becomes logical. The value becomes "0", and then returns to the logical value "1" when the filter output falls below the reference voltage Vref, and further becomes the logical value "0" when the filter output slightly exceeds the reference voltage Vref, and the high frequency drive signal. Is restored to the logical value "1" when is stopped.

Since the impedance detection signal Si is supplied to the ultrasonic energy determination circuit 20, the ultrasonic energy determination circuit 20 outputs a high frequency drive voltage from the drive circuit 7 according to the timing signal St output from the timing signal generator 28. Is output, which causes the piezoelectric element 5
Is vibrated, the ultrasonic waves generated from the acoustic lens 6 are converged on the ink surface, the ink surface rises, and the ink droplets continue to fly. As shown in FIG. 11C, the timing signal St output from the drive circuit 7 becomes the logical value “0” at the time point t1 and the drive circuit 7 outputs the high frequency drive voltage. As described above, the filter output of the impedance detection circuit 10 rises from "0" as shown in FIG. 11A, and at this time t1, the latch circuit 2
Since the latch signal of 1 continues to have the logical value "1" as shown in FIG. 11 (g), the timing signal St is inverted by the inverter 22a and supplied to the AND gate 23. When opened, the clock pulse Cp shown in FIG. 11 (d) is input to the energy amplification time measuring counter 24, so that the count value of this counter 24 is counted up as shown in FIG. 11 (h).

After that, at time t2, the filter output in the impedance detection circuit 10 exceeds the reference voltage Vref, so that the impedance detection signal Si output from the comparator 15 has a logical value "0" as shown in FIG. 11 (b).
Becomes At this time, as shown by the dotted line in FIG.
When the odd multiple of the quarter wavelength is shorter than the ink liquid surface, a time point t3 after a time relatively shorter than the time point t1 has elapsed.
Then, the filter output drops below the reference voltage Vref, and the impedance detection signal Si output from the comparator 15 becomes a logical value "1".

By supplying the impedance detection signal Si to the clock signal input terminal of the latch circuit 21, the latch output of the latch circuit 21 becomes a logical value "0" as shown in FIG. The gate 22 is closed and the energy amplification time measuring counter 24
The clock pulse Cp is stopped from being supplied to the counter 24, and the count-up of the counter 24 is stopped as shown in FIG.

The count value at this time is lower than the preset amplification time, and the amplification time error ΔTe calculated by the amplification time error calculator 26 is also "0" as shown in FIG. 11 (i). It is a small negative value. After that, when the filter output becomes larger than the reference voltage Vref at time t4, the impedance detection signal Si output from the comparator 15 becomes a logical value "0" as shown in FIG.
Thereafter, at a time point t5, the timing signal St output from the timing signal generator 28 is returned to the logical value "1" as shown in FIG. 11C, so that the previous value register 45 of the drive control circuit 40 is added by the adder 46. The subtraction output that is output from is retained as the previous value, and the output of the high frequency drive voltage is stopped from the drive circuit 7, whereby the filter output returns to "0" and the impedance detection signal Si
Returns to the logical value "1".

Thereafter, at time t6 delayed by two clock pulses Cp, the read enable signal generator 29 outputs a read enable signal SL having a logical value "0" as shown in FIG. As a result, the register 27 reads the negative amplification time error ΔTe calculated by the amplification time error calculator 26 as shown in FIG. 11 (j), and supplies this to the selection circuit 31.

At this time, the absolute value | ΔTe | of the amplification time error ΔTe calculated by the absolute value circuit 33 is calculated from the error allowable value ΔTs1 stored in the error allowable value storage circuit 33 as shown in FIG. Since it has a large value, the selection signal SC output from the comparator 35 has a logical value "1" as shown in FIG. Therefore, the movable contact tm of the switch circuit 32 is switched to the normally open contact tno which is an empty contact, so that the amplification time error Δ to the drive control circuit 40 is increased.
The supply of Te is stopped.

At the same time, in the heater drive control circuit 71, the movable contact tm of the switch circuit 72 is changed to the normally open contact tno.
By switching to the side, the amplification time error ΔTe is supplied to the proportional gain multiplier 73 and the integral gain multiplier 74 to perform proportional / integral processing, and the control output output from the adder 76 also becomes a negative value. Therefore, the previous heater command value H stored in the previous value register 77 by the adder 78
By adding a negative-valued control output to t (n-1), a heater command value Ht (n) lower than the previous heater command value Ht (n-1) is output from the adder 78, which detects an edge. The current value register 79 holds the reset signal SR from the circuit 30 at time t7. For this reason, the heater command value Ht (n) held in the current value register 79 is converted into an analog voltage by the D / A converter 80 and supplied to the heater 70, so that the temperature of the heater 70 is lowered, which causes When the ink temperature is lowered, the sound velocity C of the ultrasonic wave propagating in the ink is increased, and the wavelength λ of the ultrasonic wave is increased from the relationship of the above-mentioned formula (1). Here, as for the relationship between the ink temperature and the sound velocity C of the ultrasonic wave, as shown in FIG. 12, the sound velocity C has a large value at the temperature T1 where the ink temperature is low,
From this state, as the ink temperature increases, the speed of sound C decreases so that the rate of change gradually decreases.

Acoustic lens 6 due to the decrease in ink temperature
Since the wavelength λ of the ultrasonic wave generated from the signal is increased, when the timing signal St output from the timing signal generator 28 is turned off at the time point t8, the drive circuit 7 outputs the previous oscillation frequency command as described above. A high frequency drive voltage having a frequency corresponding to the oscillation frequency command value Vf lower than the value is output and applied to the piezoelectric element 5 to eject ink droplets. In this state, the frequency f is controlled to a low value. As a result, assuming that the wavelength λ has a large value and the focus of the acoustic lens 6 is above the ink surface, the time during which the filter output exceeds the reference voltage Vref becomes long, and accordingly, As a result, the count value of the energy amplification time measurement counter 24 slightly exceeds the preset amplification time storage value as shown in FIG. 11 (h).

Therefore, the amplification time error ΔTe calculated by the amplification time error calculator 25 becomes a positive value smaller than the error tolerance value Ts1, and this is read into the register 27 at the time t12, so that the selection circuit 31 causes the comparator. The selection signal SC of 35 is turned off. Therefore, the switch circuit 32
Since the movable contact tm of the above is switched to the normally closed contact side to the tnc side, the amplification time error ΔTe held in the register 27
Is supplied to the drive control circuit 40, and in the heater drive control circuit 70, the movable contact of the switch circuit 72 is switched to the normally-closed contact tnc side to which the digital value “0” is input to output from the adder 76. The control output is "0", and this is added by the adder 78 to the previous value register 77.
Is added to the previous value Ht (n-1) stored at time t8, the addition output becomes the previous value Ht (n-1), which is held in the current value register 79 at time t13. 70 is controlled to the same temperature as the previous time.

On the other hand, in the drive control circuit 40, time t12
At this time, the amplification time error ΔTe held in the register 28 becomes a positive value, which is input to the proportional gain multiplier 41 and the integral gain multiplier 42, and the integration circuit 43 causes the integration circuit 43 to change at time t7.
Then, the reset signal SR is turned off, and the integration content is reset when the selection signal SC is temporarily turned off as shown in FIG. The integration of the value ΔTe · Gi obtained by multiplying the amplification time error ΔTe by the integration gain Gi is started.

Therefore, a positive control output is output from the adder 44, which is supplied to the adder 78 and held in the previous value register 45. The previous frequency command value Vf (n-1).
Is added to the current value register 47 at the time t13 when the reset signal SR is turned off.
This is output to the voltage controlled oscillator 8 of the drive circuit 7 as the frequency command voltage Vf converted into an analog voltage by the D / A converter 48.

Therefore, next, the timing signal generator 28
Time t14 when the timing signal St of
Then, by applying a high frequency drive voltage of an appropriate frequency from the drive circuit 7 to the piezoelectric element 5, an odd multiple of 1/4 wavelength is made to coincide with the ink liquid surface, and the amplification time measuring counter 24
The count value of the same matches the stored amplification time value, and the amplification time error calculated by the amplification time error calculator 26 becomes “0”,
This is held in the register 27. Therefore, the addition output of the adder 44 in the drive control circuit 40 becomes “0”, so that the addition output of the adder 46 becomes the previous value register 4
The previous value held in 5 is maintained, which is held in the current value register 47 when the reset signal SR falls from the on state to the off state. Therefore, when the same frequency command value as the previous time is supplied to the voltage controlled oscillator 8 of the drive circuit 7 and the timing signal St falls from the ON state to the OFF state, the high frequency drive voltage is supplied to the piezoelectric element 5, The ultrasonic energy is controlled to the optimum state.

When the absolute value of the amplification time error ΔTe has changed by the error allowable value Ts1 or less from the state where this optimum state is continued, the drive control circuit 40 increases or decreases the frequency command value. , The optimum state is maintained, but when the absolute value of the amplification time error ΔTe exceeds the allowable error value Ts1, the selection circuit 31 selects the heater drive control circuit 71 again to increase or decrease the temperature of the heater 70. Done.

In the first embodiment, the case where the ultrasonic energy determination circuit 20 and the drive control circuit 40 are configured by hardware has been described, but the invention is not limited to this, and a microcomputer is used. It can also be configured with software. In this case, as shown in FIG.
Impedance detection signal and timing signal generator 28
The timing signal St generated in step S1 is input to the microcomputer 60, the microcomputer 60 performs a predetermined arithmetic process, and the frequency command value Vf supplied to the voltage controlled oscillator 8 of the drive circuit 7 and the heater drive circuit 80 are supplied. The temperature command value Vh to be output is output.

As shown in FIG. 14, the arithmetic processing of the microcomputer 60 is performed for a predetermined time (for example, 50 mse).
This is executed as a timer interrupt process for each c). First, in step S1, the filter output output from the filter 14 of the impedance detection circuit 10 is read through the A / D converter, and then the process proceeds to step S2 to set the timing. Signal S
It is determined whether or not an up edge at which t changes from the off state to the on state is detected. When the up edge is detected, the process proceeds to step S3, and the frequency command value Vf stored in the frequency command value storage area of the memory is set. After the output to the voltage controlled oscillator 8 of the drive circuit 7, the timer interrupt processing is terminated and the predetermined main program is restored. When the up edge is not detected, the process proceeds to step S4.

In this step S4, the timing signal S
It is determined whether or not a down edge in which t changes from the ON state to the OFF state is detected. When the down edge is detected, the process proceeds to step S5, and it is the start time of the high frequency drive voltage output in the drive circuit 7. After determining and activating the software timer, the timer interrupt processing is terminated and the predetermined main program is restored. When no down edge is detected, the process proceeds to step S6, and the timing signal St
Is ON, and when it is ON, the timer interrupt process is ended and the main program is returned to a predetermined main program. When the timing signal St is OFF, the process proceeds to step S7.

In step S7, it is determined whether or not the filter output is lower than the reference voltage Vref. If the result of this determination is that the filter output is the reference voltage Vref or higher,
In step S8, it is determined whether or not the print flag F is set to "1". When it is reset to "0", the process proceeds to step S9 and the print flag F is set to "1". After the setting, the timer interrupt processing is ended, and when the print flag F is set to "1", the timer interrupt processing is ended as it is.

If the result of the determination in step S7 is that the filter output is less than the reference voltage Vref, the process proceeds to step S10, it is determined whether or not the software timer is activated, and the software timer is not activated. Sometimes the timer interrupt process is terminated as it is and the process returns to the predetermined main program. When the software timer is activated, the process proceeds to step S11 to determine whether the print flag F is set to "1". When it is reset to "0", the timer interrupt process is terminated and the program returns to the predetermined main program. When the print flag F is set to "1", the process proceeds to step S12 and the software timer is started. Stop, then move to step S13 to reset the count value of the software timer. After being read as the nergi amplification time measurement value Te, the process proceeds to step S14.

In this step S14, the optimum energy amplification time T preset from the energy amplification time measurement value Te is set.
Amplification time error ΔTe (= Te-Te0) by subtracting e0
Of the amplification time error ΔTe is determined whether or not the absolute value | ΔTe | Then, the calculation of the following equation (3) is performed based on the amplification time error ΔT, and the temperature command value change amount Δ
Calculate Vh.

ΔVh = ΔTe · Gp + ∫ΔTe · Gi (3) Next, the process proceeds to step S17 to add the temperature command value change amount ΔVh to the previous temperature command value Vh (n-1). Is calculated as the current temperature command value Vh (n), and then the process proceeds to step S18 to update and store the temperature command value Vh (n) in the temperature command value storage area and drive the heater 70. After that, the timer interrupt process is terminated and the process returns to the predetermined main program.

On the other hand, the judgment result of the step S15 is |
When ΔTe | <Ts1, the process proceeds to step S19, and the frequency command value change amount ΔVf is calculated by performing the calculation of the following formula (4) based on the amplification time error ΔTe. ΔVf = ΔTe · Gp + ∫ΔTe · Gi (4) Next, the process proceeds to step S20, and the value obtained by adding the frequency command value change amount ΔVf to the previous frequency command value Vf (n-1) The frequency command value Vf (n) is calculated, and then the process proceeds to step S21 to update and store the frequency command value Vf (n) in the frequency command value storage area and output it to the voltage controlled oscillator 7 of the drive circuit 7. Then, the timer interrupt processing is terminated and the predetermined main program is restored.

In the first embodiment, the case where the frequency command value change amount ΔVf is calculated by performing the proportional / integral processing on the amplification time error ΔTe has been described, but the present invention is not limited to this. The frequency command value change amount ΔVf may be calculated by performing any one or more of the proportional process, the integral process, and the differential process. Further, the constant frequency command value change amount ΔVf may be set. May be.

Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, the distance between the acoustic lens 6 and the ink surface is 1 due to the influence of the ink viscosity.
This is to be corrected when the wavelength is changed from an odd multiple of / 4 wavelength. That is, in the second embodiment, as shown in FIG. 15, the ultrasonic energy determination circuit 20 has the latch circuit 21, the inverter 22a and the AND gate 2 in the configuration of FIG. 3 in the first embodiment described above.
2. The error detection circuit 23 is omitted, and instead of these, the impedance detection signal Si supplied from the impedance detection circuit 10 to the input side, the clock pulse Cp, and the timing signal of the timing signal generator 28 are the inverter 5
It has the same configuration as that of FIG. 3 except that an AND gate 50b that is inverted by 0a and is input, and an error detection circuit 51 that receives the output pulse of the AND gate 50b are provided. The same reference numerals are given to the portions corresponding to 3, and the detailed description thereof is omitted.

The error detection circuit 51 includes a liquid level amplitude time measuring counter 5 to which the output pulse of the AND gate 50 is input.
2. The amplitude time storage circuit 53, and the amplitude time error calculator 54 that calculates the amplitude time error by subtracting the count value of the liquid surface amplitude time measurement counter 52 from the amplitude time storage value stored in the amplitude time storage circuit 53 are provided. Then, the calculation result of the amplitude time error calculator 54 is configured to be held in the register 55, and the amplitude time error held in the register 55 is supplied to the selection circuit 31. This selection circuit 31 also has the same configuration as that of FIG. 4, but the error allowable value Ts2 is set by the error allowable value setting circuit 34 supplied to the comparator 35. Further, the drive drive control circuit 40 outputs an amplitude command value Va, which is supplied to the voltage control amplifier 8 of the drive circuit 7 to control the amplitude of the high frequency drive voltage.

Next, the operation of the second embodiment will be described. First, the operating principle of the second embodiment will be described. When the viscosity of the ink is high, the attenuation of ultrasonic energy becomes large, and proper sound pressure cannot be concentrated on the ink surface. That is, the attenuation of the sound pressure P with respect to the focal length x is given by the following equation (5).

P (x) = P ₀ e ^{−α · x} (5) α = 2ω ² μ / 3c ³ ρ = 8 (πf) ² μ / 3c ³ ρ (6) Here Where α is the damping coefficient, μ is the viscosity (Pa · s), f is the excitation frequency (Hz), and P0 is the sound source sound pressure. When the ultrasonic energy is accumulated / amplified in the ink liquid and the ink droplets are ready to fly, the ink liquid surface rises rapidly as described above, and the ink droplets fly. At this time, a load change occurs, and this load change can be detected as a change for a certain period of time if the ink surface has an appropriate ink viscosity.

That is, when the ink viscosity is at an appropriate value, the amount of swelling of the ink surface is generated as shown in FIG. 16A when the oscillation voltage initial set value Va is applied from the drive circuit 7 to the piezoelectric element 5. Is appropriate and the amplitude change time in the drive current waveform between the piezoelectric element 5 and the shunt resistor Rs is in an appropriate state, but when the ink viscosity is lower than the appropriate value, as shown in FIG. The swelling of the surface is high, and the amplitude change time in the drive current waveform between the piezoelectric element 5 and the shunt resistor Rs becomes long.

Further, when the ink viscosity is high, as shown in FIG.
As shown in FIG. 6 (c), the rise of the ink surface is small, and the amplitude change time in the drive current waveform between the piezoelectric element 5 and the shunt resistor Rs is short or undetectable. In this case, the voltage of the high frequency drive voltage Deal by raising. Therefore, when the ink viscosity is now high, the amplitude time error ΔTa held in the register 27 in the ultrasonic energy determination circuit 20 is a positive value and the error allowance of the amplification time error ΔTa is shown in FIG. 17 (i). It is assumed that the value is larger than the value Ts2.

In this state, the comparator 35 of the selection circuit 31
As shown in FIG. 17 (k), since the selection signal SC output from the ON state is in the ON state, the movable contact tm in the switch circuit 32 of the selection circuit 31 is switched to the normally open contact tno side, so that the drive control is performed. The output of the amplification time error ΔTa to the circuit 40 is stopped. At this time, in the heater drive control circuit 70, similarly to the first embodiment, the movable contact tm of the switch circuit 72 is switched to the normally open contact tno side, and the amplitude time error ΔTa is subjected to proportional / integral (PI) processing. Since the addition output output from the adder 76 is also a positive value,
By supplying this addition output to the adder 78, the previous temperature command value Vh held in the previous value register 45
The addition output is added from (n-1), and the temperature command value Vh (n) higher than the previous oscillation voltage command value Vh (n-1) is held in the current value register 79, which is stored in the D / A converter 80. And is supplied to the heater 70 as the temperature command voltage Vh. Therefore, the ink temperature is raised and the ink viscosity is lowered. Here, as for the relationship between the ink temperature and the ink viscosity, as shown in FIG. 18, the ink viscosity has a large value at the temperature T2 where the ink temperature is low, and when the ink temperature is increased from this state, the change rate of the ink viscosity changes. Has a relationship of decreasing gradually and becomes a viscosity region in which ink droplets can fly at a set temperature T3 higher than the ink temperature T2.

In this state, when the timing signal St generated by the timing signal generator 28 is turned off at time t21, the error detection circuit previous value register 45 causes the adder 46 to operate.
The addition output of is held as the previous oscillation voltage command value, and the drive circuit 7 applies a high frequency drive voltage of relatively small amplitude to the piezoelectric element 5. At this time, assuming that the distance between the acoustic lens 6 and the ink surface is in an appropriate state, the filter output exceeds the reference voltage Vref at time t22 as shown in FIG. The impedance detection signal Si output from the comparator 15 is turned off, and thereafter at time t23, the filter output falls below the reference voltage Vref, so that the impedance detection signal Si is turned on as shown in FIG. 17B. Therefore, the AND gate 50b opens,
The clock pulse Cp is the counter 52 for measuring the liquid surface amplitude time.
The count value is incremented by being input to. At this time, the ink viscosity is high.
As shown in (c), the rise of the ink surface is small,
The impedance detection signal Si output from the impedance detection circuit 10 is turned off because the filter output exceeds the reference voltage Vref at a time point t24 when a short time has elapsed from the time point t23, and the AND gate 50b is closed to close the liquid surface. The counting up of the amplitude time measuring counter 52 is stopped. At this time, since the count value becomes a small value "1", the amplitude time error calculated by the amplitude time calculator 54 maintains a positive value as shown in FIG. 17 (h).

After that, when the timing signal St generated by the timing signal generator 28 is turned on at time t25, the output of the high frequency drive voltage from the drive circuit 7 to the piezoelectric element 5 is stopped, and the clock pulse Cp causes 2 to be output.
At the time point t26 delayed by one time, the read permission signal output from the read permission signal generator 29 is turned off, whereby the positive value calculated by the amplitude time error calculator 54 in the register 55 is slightly smaller than the error allowable value Ts2. Large amplitude time error Δ
Ta is read.

Therefore, the temperature rise control in the heater drive control circuit 71 is continued, the ink temperature is raised, and the ink viscosity is lowered accordingly. After that, at time t28, a high-frequency drive voltage having a predetermined amplitude is applied from the drive circuit 7 to the piezoelectric element 5.
Applied to. At this time, assuming that the distance between the acoustic lens 6 and the liquid surface of the ink is in an appropriate state, the filter output shows the reference voltage Vref at time t29 as shown in FIG.
17B, the impedance detection signal Si output from the comparator 15 of the impedance detection circuit 10 is turned off. Then, at time t30, the filter output falls below the reference voltage Vref. ), It is turned on.
Therefore, the AND gate 50b is opened and the clock pulse Cp is input to the liquid level amplitude time measuring counter 52, whereby the count value is counted up.

At this time, if the ink temperature rises and the ink temperature rises too much, the liquid level amplitude time between time points t30 and t31 becomes longer, so that the count value of the liquid level amplitude time measuring counter 52 is increased. As shown in FIG. 17 (g), the amplitude time memory value Ta0 is exceeded. For this reason,
Amplitude time error ΔT calculated by the amplification time error calculator 54
When a is a negative value and its absolute value is smaller than the error allowable value Ts2 as shown in FIG. 17 (h), this is the time t33.
Is read into the register 55 and output to the selection circuit 31. Therefore, when the selection signal SC output from the comparator 35 of the selection circuit 31 is turned off as shown in FIG. 17 (k), the drive control circuit 40 is selected by the selection circuit 31 and the amplitude time error ΔTa. Is output to the drive control circuit 40.

In this drive control circuit 40, the adder 46 adds the correction value output from the adder 44 which is the proportional / integral processing of the amplitude time error ΔTa to the previous oscillation voltage command value Va (n-1). , From this adder 46, the oscillation voltage command value Va (n) smaller than the previous oscillation voltage command value Va (n-1)
Is output, which is held in the current value register 47 at time t34, converted into an analog voltage by the D / A converter 48, and supplied to the voltage control type amplifier 9 of the drive circuit 40. Therefore, the amplitude of the high frequency drive voltage output from the drive circuit 7 at time t35 is controlled to a value smaller than the previous value, and the count value of the liquid surface amplitude time measuring counter 52 is stored in the amplitude time storage circuit 53. It is matched to the stored amplitude time stored value.

Therefore, the amplitude time error ΔTa output from the time error calculation circuit 54 becomes “0”, which is held in the register 55 at the time t41 and output to the selection circuit 31. The held amplitude time error ΔTa is supplied to the drive control circuit 40, so that the drive control circuit 40
Since the value subjected to the proportional / integral processing becomes "0", the current oscillation voltage command value output from the adder 46 maintains the previous value, and this value is stored in the current value register 47 at the subsequent time t42. It is held, converted into an analog signal by the D / A converter 48, and supplied to the voltage control type amplifier 9 of the drive circuit 7.

Therefore, after that, the timing signal St
The drive circuit 7 is turned on when the
A high-frequency drive voltage that maintains the previous value is output from the device to form a swell on the ink surface according to the ink viscosity, and the ink droplets can be reliably ejected and attached to the recording medium. After that, while the amplitude voltage control according to the ink viscosity is being performed, the ink temperature changes and the absolute value of the amplitude time error ΔTa held in the register 55 exceeds the error allowable value Ts2. As described above, the heater drive control circuit 71 is selected by the selection circuit 31, and the ink temperature is controlled.

In the second embodiment, the case where the ultrasonic energy judgment circuit 20 and the drive control circuit 40 are configured by hardware has been described, but the present invention is not limited to this, and a microcomputer is used. It can also be configured with software. In this case, as shown in FIG.
Impedance detection signal and timing signal generator 28
The timing signal St generated in 1 is input to the microcomputer 60, the microcomputer 60 performs a predetermined arithmetic processing, and the temperature command value Vh supplied to the heater drive circuit 80 and the voltage control type amplifier 9 of the drive circuit 7 are supplied. The oscillation voltage command value Va is output.

In the calculation process of the microcomputer 60, the ink viscosity correction process shown in FIG. 20 is performed by a timer interrupt process at every predetermined time (for example, 50 msec). In the ink viscosity correction process, first, in step S31, the filter output output from the filter 14 of the impedance detection circuit 10 is read through the A / D converter, and then the process proceeds to step S32 to perform the timing signal generator 28.
It is determined whether or not an up edge in which the timing signal St output from is changed from the off state to the on state is detected. When the up edge is detected, step S3 is performed.
3, the oscillation voltage command value Va stored in the oscillation voltage command value storage area formed in the memory is output to the voltage control type amplifier 9 of the drive circuit 7, and then the timer interrupt processing is ended and predetermined. Return to the main program of.

When the determination result of step S32 does not detect the rising edge of the timing signal St, the process proceeds to step S34, it is determined whether or not the timing signal St is in the on state, and it is in the on state. Sometimes, the timer interrupt process is finished as it is and the predetermined main program is returned to. If it is in the off state, step S3
Go to 5.

In step S35, it is determined whether or not the filter output is equal to or higher than the reference voltage Vref based on the oscillation voltage command value Va stored in the oscillation voltage command value storage area, and the filter output is less than the reference voltage Vref. If there is, the process proceeds to step S36, and the print flag F is "1".
If it is set to "0", it is reset to "0" and the timer interrupt processing is terminated and the main program is returned to the print flag F.
When is set to "1", the process proceeds to step S37, and it is determined whether or not the liquid surface amplitude measuring timer is started. When it is started, the timer interrupt process is ended and the predetermined value is set. If the liquid level amplitude measuring timer is not activated, the process proceeds to step S38 to activate the liquid level amplitude measuring timer, terminate the timer interrupt process, and return to the predetermined main program. To do.

On the other hand, when the result of the determination in step S35 is that the filter output is equal to or higher than the reference voltage Vref, the process proceeds to step S39, and it is determined whether or not the print flag F indicating the print state is set to "1". When it is reset to "0", the process proceeds to step S40, the print flag F is set to "1", the timer interrupt process is ended, and the predetermined main program is restored. When it is set to "1", the process proceeds to step S41, and it is determined whether or not the liquid level amplitude measuring timer is activated. Returning to the main program, when the liquid surface amplitude measuring timer is activated, the process proceeds to step S42.

In step S42, the liquid surface amplitude measuring timer is stopped, and then the process proceeds to step S43,
The liquid surface amplitude time Ta measured by the liquid surface amplitude measuring timer is read, then the process proceeds to step S44, and the liquid surface amplitude time Ta is subtracted from the preset liquid surface amplitude time stored value Ta0 to obtain the liquid surface amplitude time error. ΔTa (= Ta0-Ta) is calculated.

Next, in step S45, the absolute value | ΔTa | of the amplitude width time error ΔTa is equal to the allowable error value Ts.
It is determined whether or not 2 or more, and if | ΔTa | ≧ Ts2, the process proceeds to step S46, and the temperature command value change amount ΔVh is calculated by performing the calculation of the following equation (5) based on the amplitude width time error ΔTa. To calculate. ΔVh = ΔTa · Gp + ∫ΔTa · Gi (5) Next, the process proceeds to step S47, and the value obtained by adding the temperature command value change amount ΔVh to the previous temperature command value Vh (n-1) is used. The temperature command value Vh (n) is calculated, and then the process proceeds to step S48 to update and store the temperature command value Vh (n) in the temperature command value storage area and output it to the heater drive circuit 80 that drives the heater 70. Then, the timer interrupt processing is terminated and the predetermined main program is restored.

On the other hand, the determination result of step S45 is |
When ΔTa | <Ts2, the process proceeds to step S49, and the amplitude command value change amount ΔVa is calculated by performing the calculation of the following equation (6) based on the amplitude time error ΔTa. ΔVa = ΔTa · Gp + ∫ΔTa · Gi (6) Next, the process proceeds to step S50, and the value obtained by adding the amplitude command value change amount ΔVa to the previous amplitude command value Va (n-1) is calculated. The amplitude command value Va (n) is calculated, and then the process proceeds to step S51 to update and store the amplitude command value Va (n) in the amplitude command value storage area, and output it to the voltage control type amplifier 8 of the drive circuit 7. Then, the timer interrupt processing is terminated and the predetermined main program is restored.

Also in the second embodiment described above, the case where the oscillation voltage command value change amount ΔVa is calculated by performing the proportional / integral processing on the liquid surface amplitude time error ΔTa has been described, but the present invention is not limited to this. However, the oscillation voltage command value change amount ΔVa may be calculated by performing one or more of a proportional process, an integration process, and a differential process, and further, a constant value of the oscillation voltage command value change amount ΔVa. May be set.

Next, a third embodiment of the present invention will be described with reference to FIGS. This third embodiment is a combination of the above-described first and second embodiments, in which the ultrasonic lens 6 is generated on the ink liquid surface in response to both the fluctuation of the ink liquid surface and the change of the ink viscosity. The sound waves are made to converge. That is, in the third embodiment, as shown in FIG. 21, the ultrasonic energy determination circuit 20 includes the first error detection circuit 56A including the error detection circuit 23 in the first embodiment and the second error detection circuit 56A. The second error detection circuit 56B configured by the error detection circuit 51 in the embodiment
And the amplitude-time error calculator 5 of the second error detection circuit 56B
The third register 57 that holds the amplitude time error ΔTa calculated in 4 with the read permission signal SL output from the read permission signal generator 29, and the registers 27 and 55 in the first and second error detection circuits 56A and 56B. Controlling the holding timing of the heaters and selecting the holding data of the registers 27 and 55 and the third register 57 to supply the oscillation frequency command value to the heater drive control circuit 71 and the voltage controlled oscillator 8 of the drive circuit 7. 1 except that the drive control circuit 40A and the voltage control type amplifier 9 of the drive circuit 7 are provided with a selection circuit 58 that supplies the oscillation voltage command value to any of the second drive control circuits 40B. Has the same configuration as that of FIGS. 3 and 15 of the first and second embodiments described above, and the same reference numerals are given to the corresponding portions with FIGS. 3 and 15.
The detailed description thereof will be omitted.

Here, as shown in FIG. 22, the selection circuit 57 outputs the amplification time error ΔTe output from the register 27 of the first error detection circuit 56A to the first absolute value circuit 91A.
Connected to the first comparator 93A to which the error tolerance value set by the error tolerance value setting circuit 92A is input to the non-inverting input side and the output side of the first comparator 93A via the The latch circuit 94 for performing the down edge operation, the latch signal output from the inverted output side of the latch circuit 94, and the read permission signal SL output from the read permission signal generator 29 are input, and the output SL1 is The first AND gate 95A supplied to the register 27 of the first error detection circuit 56A and the amplitude time error output from the register 55 of the second error detection circuit 56B are not transmitted via the second absolute value circuit 91B. A second comparator 93B to which the error tolerance value set by the error tolerance value setting circuit 92B is input to the inverting input side and the output of the second comparator 93B are input to the down edge. Created and supplied to the latch circuit 94 an edge detection signal as a reset signal edge detecting circuit 96
And the comparison output of the first comparator 93A is the inverter 100
Read enable signal SL from the read enable signal generator 29, and the output SL2.
Is supplied to the register 55 of the second error detection circuit 56B, and the amplitude time error ΔTa output from the third register 57 is supplied to the non-inverting input side via the third absolute value circuit 91C. Switching control is performed by the third comparator 93C to which the error allowable value Ts3 set by the third error allowable value setting circuit 92C is input on the inverting input side, and the selection signal SC output from the third comparator 93C. A first switch circuit 97A and a second switch circuit 97B,
The AND gate 98 receives the selection signal SC output from the third comparator 93C and the reset signal SR output from the edge detection circuit 30 and outputs a drive circuit reset signal DR.

The amplification time error ΔTe output from the normally closed contact of the first switch circuit 97A is applied to the first drive control circuit 40A, and the amplitude time error ΔTa output from the second switch circuit 97B is applied to the second drive control circuit 40A. The amplitude time error ΔTa output from the third register is supplied to the heater drive control circuit 71, and the selection signal SC output from the third comparator 93C is input to the heater drive control circuit 71. The drive circuit reset signal DR output from the AND gate 98 is the first and second drive circuits 40A and 40A.
It is output to 0B.

Next, the operation of the third embodiment will be described. Now, in the third register 57, the read permission signal generator 2
9. The amplitude time error ΔTa calculated by the amplitude time error calculator 54 at the timing when the read permission signal SL of No. 9 is turned off.
When the amplitude time error ΔTa is equal to or larger than the error allowable value Ts3 set by the third error allowable value setting circuit 92C, the selection signal SC output from the third comparator 93C is in the ON state. Therefore, the first and second
Switch circuits 97A and 97B are switched to the normally open contact side, and the first and second drive control circuits 40A and 40B
However, the output of the amplification time error ΔTe and the amplitude time error ΔTa is stopped.
The amplitude time error ΔTa held by the register 57 is output and ink temperature control is performed.

After that, when the amplitude time error ΔTa held in the third register 57 becomes less than the third error allowable value Ts3, the selection signal SC output from the third comparator 93C is inverted to the off state. , Heater drive control circuit 71
Control of the ink temperature is stopped, and instead of this, the first and second switch circuits 97A and 97B are switched to the normally-closed contact side so that the first error detection circuit 56A and the second error detection circuit 56B respectively. The amplification time error ΔTe and the amplitude time error ΔTa held in the registers 27 and 55 are ready to be supplied to the first and second drive control circuits 40A and 40B.

In this state, the latch signal output from the latch circuit 94 is in the on state, and this is the AND gate 9
5A. In this state, as in the first embodiment described above, the read permission signal generator 29
From the ON state to the OFF state, the output of the AND gate 95A is inverted to the OFF state, which is the register 27 of the first error detection circuit 56A.
Is supplied to the drive control circuit 40A by holding the amplification time error calculated by the amplification time error calculator 26 in the register 27 and being supplied to the drive control circuit 40A. The current oscillation frequency command value is formed based on the amplification time error and the previous oscillation frequency command value, and this oscillation frequency command value is supplied to the voltage controlled oscillator 8 of the drive circuit 7, whereby the drive circuit 7
Supplies a high frequency drive voltage Vf having a frequency corresponding to the oscillation frequency command value to the piezoelectric element 5, outputs an ultrasonic wave that converges to the ink liquid surface from the acoustic lens 6, raises the ink liquid surface, and causes ink droplets to fly. And adhere to the recording medium to form dots.

By performing a correction process for matching the ink liquid surface with the convergence point of the ultrasonic wave generated by the acoustic lens 6, when the ultrasonic wave generated by the acoustic lens 6 converges near the ink liquid surface, The amplification time error ΔTe output from the register 27 of the first error detection circuit 56A becomes substantially “0”, and this is supplied to the first comparator 93A via the absolute value circuit 91A, whereby this amplification time error ΔTe. When ΔTe becomes a value smaller than the first error allowable value set by the first error allowable value setting circuit 92A, the comparison output output from the first comparator 93A is inverted to the off state,
By supplying this to the latch circuit 94, the latch signal output from this latch circuit 94 is inverted from the ON state to the OFF state, and by supplying this to the AND gate 95A, the AND gate 95A is closed,
The reading of the register 27 in the first error detection circuit 56A is stopped.

At the same time, the comparison output obtained by inverting the first comparator 93A from the on-state to the off-state is the inverter 10
By being supplied to the AND gate 95B via 0, the AND gate 95B is brought into the open state, and when the read permission signal from the ON state to the OFF state is input from the read permission signal generator 29, this is changed to the second state. Is supplied to the register 55 of the error detection circuit 56B, the amplitude time error calculated by the amplitude time error calculator 54 is held in this register 55, and this is supplied to the second drive control circuit 40B. The drive control circuit 40B calculates an oscillation voltage command value according to the ink viscosity, and supplies this to the voltage-controlled amplifier 9 of the drive circuit 7, whereby a high-frequency oscillation voltage with an amplitude corresponding to the oscillation voltage command value is piezoelectric. It is output to the element 5.

After that, the amplitude time error held in the register 55 of the second error detection circuit 56B is controlled to "0" by controlling the amplitude of the high frequency drive voltage output from the drive circuit 7 to the optimum state for the ink viscosity. "Because it is a value in the vicinity of the second
When the error tolerance value set by the error tolerance value setting circuit 92B is less than the error tolerance value, the comparison output output from the second comparator 93B is inverted to the off state.
6 and is supplied to the latch circuit 94 as a reset signal, the latch output of the latch circuit 94 is turned on, the AND gate 95A is opened, and the first error detection circuit 56A is operated. A correction process is performed to converge the ultrasonic waves generated by the acoustic lens 6 on the ink liquid surface.

In this state, when the amplitude time error ΔTa calculated by the third absolute value circuit 91C and held in the third register 57 becomes equal to or larger than the third error allowable value Ts3, the heater drive control circuit 71 causes Return to ink temperature control.
As described above, in the third embodiment, the correction process for converging the ultrasonic waves generated by the ink liquid surface and the acoustic lens 6 to the ink liquid surface and the ink viscosity are performed according to the ink viscosity in the state where the ink temperature becomes the appropriate value. By alternately repeating the correction process of generating the high frequency drive voltage of the amplitude, the ultrasonic energy can be always maintained in the optimum state according to the fluctuation of the ink surface and the fluctuation of the ink viscosity, and the ink droplet flying Can be accurately controlled to improve the print quality.

In the third embodiment, the first error detection circuit 56A and the second error detection circuit 56B are used.
However, the present invention is not limited to this, and since the change of the ink liquid level is faster than the change of the ink viscosity, the first error detection circuit 56A is operated a plurality of times. The second error detection circuit 56B may be operated once after the continuous operation.

In the third embodiment, the case where the ultrasonic energy judgment circuit 20 and the drive control circuit 40 are composed of hardware has been described, but the present invention is not limited to this. The arithmetic processing using the microcomputer of the second embodiment is performed, and in either one of the arithmetic processing, the frequency command value change amount ΔV
When f or the oscillation voltage command value change amount ΔVa falls within a preset allowable range, the other calculation process may be switched to.

Further, in the above-described first to third embodiments, the case where the present invention is applied to the ink jet printer using the recording liquid as the ink has been described, but the present invention is not limited to this, and liquids other than ink are used. The present invention can be applied to the case of flying the droplets.

[0104]

As described above, according to claim 1 or 12,
According to the invention according to, the impedance of the drive system for driving the piezoelectric element is detected by the high-frequency drive means, and it is determined whether or not the ultrasonic energy is appropriate based on the impedance detection signal, and the determination defect is determined. Since the recording liquid temperature is controlled on the basis of the recording liquid temperature, it is possible to accurately detect the droplet flying state in real time without separately providing a sensor for detecting the temperature, the viscosity, the sound speed, etc. By suppressing the change in the viscosity of the recording liquid due to changes,
The effect that the recording quality can be improved by accurately converging the ultrasonic waves generated by the acoustic lens on the surface of the recording liquid is obtained. Moreover, in order to measure the state of the recording liquid or the sound source, it is not necessary to provide a special measurement time in the non-ejection state of the recording liquid, and by providing the measurement time, it is possible to ensure that the ejection time of the recording liquid is delayed. There is also an effect that can be prevented.

According to the second aspect of the present invention, the impedance detecting means includes drive current detecting means for detecting the drive current of the piezoelectric element, and the drive current detected by the drive current detecting means is converted into a DC voltage change. Current waveform processing means for
Since the output voltage of the current waveform processing means and the reference voltage are compared with each other, the liquid level change and the viscosity change of the recording liquid can be detected at the same time.

Further, according to the invention of claim 3 or 14, the ultrasonic energy is judged by measuring the impedance change time from the drive start to the impedance change point based on the impedance detection signal, and the impedance change time is measured. Based on the above, the positional relationship between the liquid surface of the driving focal length and the sound pressure is appropriate, and the ultrasonic wave is properly accumulated by the standing wave in the recording liquid generated between the liquid surface of the recording liquid and the acoustic lens.
Since it is done by judging whether or not it is amplified,
The effect that the change in the liquid level of the recording liquid can be accurately detected in real time is obtained.

Further, according to the invention of claim 4, there is an effect that the viscosity of the recording liquid can be controlled to an appropriate value by changing the temperature of the recording liquid by the temperature control means. Still further, according to the invention of claim 5 or 15, temperature control is performed when the amplification time error calculated when determining the ultrasonic energy is out of the allowable range, and when the piezoelectric energy is within the allowable range, the piezoelectric element is turned on. Since the frequency of the high-frequency drive signal supplied is controlled, the wavelength of ultrasonic waves generated by the acoustic lens in the recording liquid can be accurately controlled to an appropriate state.

According to the sixth aspect of the invention, when the wavelength of the ultrasonic waves generated by the acoustic lens in the recording liquid is short, the wavelength is long, and when the wavelength is long, the wavelength is controlled to be short to control the wavelength appropriately. The effect that can be obtained is obtained. Further, according to the invention of claim 7 or 16, the ultrasonic energy determination means measures the amplitude time from the change point of the impedance to the next change point based on the impedance detection signal, and the viscosity of the recording liquid is appropriate. Therefore, it is configured to judge whether or not the ultrasonic energy is properly accumulated and amplified by the standing wave in the recording liquid generated between the liquid surface of the recording liquid and the acoustic lens. It is possible to obtain an effect that the generation state of ultrasonic waves according to the change can be accurately determined in real time.

According to the eighth aspect of the present invention, the drive control means increases the drive voltage of the high frequency drive means when the determination result of the ultrasonic energy determination means is shorter than the optimum amplitude time. Since the control is performed to lower the drive voltage of the high frequency drive unit when the time is longer than the optimum time, the amplitude of the high frequency drive signal supplied to the piezoelectric element can be accurately corresponded to the change of the recording liquid viscosity. The effect of being able to be obtained is obtained.

Further, according to the invention of claim 9 or 10, since the amplitude of the high frequency signal supplied to the piezoelectric element is controlled based on the judgment result of the ultrasonic energy judging means, it is suitable for the viscosity of the recording liquid. The effect that the droplet flying control can be performed is obtained. Furthermore, in the invention according to claim 11, the ultrasonic energy determination means measures the impedance change time from the drive start to the impedance change point based on the impedance detection signal,
Based on the impedance change time, the positional relationship between the liquid surface of the driving focal length and the sound pressure is proper, and the ultrasonic wave is properly accumulated by the standing wave in the recording liquid generated between the liquid surface of the recording liquid and the acoustic lens. The first to judge whether or not it is amplified
And the amplitude time from the point of change of impedance to the next point of change of the impedance, the viscosity of the recording liquid is appropriate, and the ultrasonic wave is generated by the standing wave in the recording liquid generated between the liquid surface of the recording liquid and the acoustic lens. A second judgment means for judging whether or not the sound wave energy is properly accumulated / amplified, and the drive control means, when the judgment result of the first judgment means is shorter than the optimum time. Of the first drive control means for controlling the frequency of the high frequency drive signal of the high frequency drive means to be low and for increasing the frequency of the high frequency drive signal of the high frequency drive means when the frequency is longer than the optimum time. A second drive control for performing control to increase the drive voltage of the high frequency drive means when the determination result is shorter than the optimum amplitude time and to lower the drive voltage of the high frequency drive means when longer than the optimum time. Since a stage, it is possible to obtain the effect of the invention towards the claims 3 and 7.

Furthermore, according to the thirteenth aspect of the present invention, when the ultrasonic energy is not appropriate, the recording liquid temperature is controlled, and after the ultrasonic energy is brought into the appropriate state by the recording liquid temperature control, the high frequency driving means is provided. Since the frequency is controlled, it is possible to obtain an effect that the wavelength of the ultrasonic wave generated by the acoustic lens in the recording liquid can be accurately controlled to an appropriate state.

According to the fifteenth aspect of the invention, temperature control is performed based on the ultrasonic energy determination result, and control is performed to control the frequency of the high frequency signal supplied to the piezoelectric element after the temperature control is completed. Appropriate flight control of recording liquid droplets can be performed. Further, according to the invention of claim 17, the temperature control is performed based on the ultrasonic energy determination result, and after the temperature control is converged, the control for controlling the amplitude of the high frequency signal supplied to the piezoelectric element is performed. It is possible to perform more appropriate flight control of the recording liquid in consideration of the above. Further, according to the invention of claim 18, the effects of both claims 16 and 17 can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a specific example of an impedance detection circuit.

FIG. 3 is a block diagram showing a specific example of an ultrasonic energy determination circuit.

FIG. 4 is a block diagram showing a specific example of a selection circuit.

FIG. 5 is a block diagram diagram showing a specific example of a drive control circuit.

FIG. 6 is a block diagram showing a specific example of a heater drive control circuit.

FIG. 7 is an explanatory diagram showing a positional relationship between a liquid surface having a focal length and sound pressure.

FIG. 8 is an explanatory diagram illustrating a locus of current waveform change.

FIG. 9 is a time chart showing a change in current when ink droplets are not generated.

FIG. 10 is a time chart showing a change in current when ink droplets are generated.

FIG. 11 is a time chart used for explaining the operation of the first embodiment.

FIG. 12 is a characteristic diagram showing the relationship between ink temperature and sound velocity.

FIG. 13 is a block diagram showing another embodiment of the first embodiment.

14 is a flowchart showing an example of a calculation processing procedure in the microcomputer shown in FIG.

FIG. 15 is a block diagram showing a second embodiment of the present invention.

FIG. 16 is an explanatory diagram showing a detection principle in the second embodiment.

FIG. 17 is a time chart for explaining the operation of the second embodiment.

FIG. 18 is a characteristic diagram showing the relationship between ink temperature and ink viscosity.

FIG. 19 is a block diagram showing another embodiment of the second embodiment.

20 is a flowchart showing an example of an arithmetic processing procedure in the microcomputer shown in FIG.

FIG. 21 is a block diagram showing a third embodiment of the present invention.

FIG. 22 is a block diagram showing a specific example of a selection circuit according to the third embodiment.

[Explanation of symbols]

1 Droplet ejection recording device 2 Ink storage 3 nozzles 4 case body 5 Piezoelectric element 6 acoustic lens 7 drive circuit 8 Voltage controlled oscillator 9 Voltage control type amplifier 10 Impedance detection circuit 11 Current waveform processing circuit 12 amplifier 13 full-wave rectifier 14 filters 15 Comparator 20 Ultrasonic energy judgment circuit 23 Error detection circuit 28 Timing signal generator 29 Read permission signal generator 31 selection circuit 40 Drive control circuit 51 Error detection circuit 56A First error detection circuit 56B Second error detection circuit 57 Third Register 58 selection circuit 60 microcomputer 70 heater 71 Heater drive control circuit

Claims (18)

[Claims] 1. An ultrasonic lens generated on the acoustic lens is recorded by arranging an acoustic lens arranged on the upper surface of a piezoelectric element in a recording liquid storage section and driving the piezoelectric element at a high frequency by a high frequency driving means. In a droplet jet recording apparatus in which recording droplets are made to fly by converging on a recording liquid surface of a liquid storage portion, impedance detection means for detecting impedance of a drive system for driving the piezoelectric element by the high frequency drive means, Ultrasonic energy determination means for determining whether or not the energy of ultrasonic waves is appropriate based on the impedance detection signal detected by the impedance detection means,
A droplet jet recording apparatus, comprising: temperature control means for controlling the temperature of the recording liquid based on the determination result of the ultrasonic energy determination means. 2. The impedance detecting means includes a drive current detecting means for detecting a drive current of a piezoelectric element, a current waveform processing means for converting the drive current detected by the drive current detecting means into a DC voltage change, and the current. 2. The liquid droplet jetting recording apparatus according to claim 1, further comprising: comparing means for comparing the output voltage of the waveform processing means and the reference voltage, and the impedance detecting signal is output from the comparing means. 3. The ultrasonic energy judging means measures the energy amplification time from the driving start to the impedance change point based on the impedance detection signal, and the energy amplification time measuring means measures the energy amplification time. 3. The droplet jet recording apparatus according to claim 1, further comprising amplification time error calculation means for calculating an error between the energy amplification time and the optimum amplification time. 4. The temperature control means increases the recording liquid temperature when the energy amplification time of the ultrasonic energy determination means is longer than the optimum amplification time, and lowers the recording liquid temperature when the energy amplification time is shorter than the optimum amplification time. The droplet jet recording apparatus according to claim 3, wherein the droplet jet recording apparatus is configured as follows. 5. The frequency control means for controlling the frequency of the high frequency drive means based on the judgment result of the ultrasonic energy judgment means, and the amplification time error calculated by the amplification time error calculation means of the ultrasonic energy judgment means. Amplification time error determination means for determining whether the amplification time error is within an allowable range, and the amplification time error is supplied to the temperature control means when the amplification time error is outside the allowable range according to the determination result of the amplification time error determination means. The droplet ejection recording apparatus according to claim 3, further comprising a selection unit that supplies the amplification time error to the frequency control unit when the amplification time error is within an allowable range. 6. The frequency control means lowers the frequency of the high frequency drive signal of the high frequency drive means when the determination result of the ultrasonic energy determination means is shorter than the optimum amplification time, and when the determination result is longer than the optimum amplification time. 6. The droplet ejection recording apparatus according to claim 5, wherein the droplet ejection recording apparatus is configured to perform control for increasing the frequency of the high frequency drive signal of the high frequency drive means. 7. The liquid level amplitude time measuring means for measuring the amplitude time from the impedance changing point to the next changing point based on the impedance detection signal, and the liquid surface amplitude time measuring means. 3. An amplitude time error calculating means for calculating an error between the liquid level amplitude time measured in step 1 and the optimum amplitude time is provided.
The droplet jet recording apparatus according to item 1. 8. The temperature control means increases the recording liquid temperature when the liquid surface amplitude time of the ultrasonic energy determining means is longer than the optimum amplitude time, and lowers the recording liquid temperature when the liquid surface amplitude time is shorter than the optimum amplitude time. The droplet jet recording apparatus according to claim 7, wherein the droplet jet recording apparatus is configured as described above. 9. An amplitude control means for controlling the amplitude of the high frequency driving means based on the determination result of the ultrasonic energy determination means, and an amplitude time error calculated by an amplitude time error calculation means of the ultrasonic energy determination means. Amplitude time error determination means for determining whether the amplitude time error is within the allowable range, and when the determination result of the amplitude time error determination means is that the amplitude time error is outside the allowable range, the amplitude time error is supplied to the temperature control means. The droplet ejection recording apparatus according to claim 7, further comprising: a selection unit that supplies the amplitude time error to the amplitude control unit when the amplitude time error is within an allowable range. 10. The amplitude control means increases the drive voltage of the high frequency drive means when the determination result of the ultrasonic energy determination means is shorter than the optimum amplitude time, and increases the drive voltage of the high frequency drive means when longer than the optimum time. 10. The control unit is configured to perform control for lowering the drive voltage.
The droplet jet recording apparatus described. 11. The ultrasonic energy determining means measures an energy amplification time from the start of driving to a change point of impedance based on an impedance detection signal, and an energy amplification time measuring means. A first judgment means having an amplification time error calculation means for calculating an error between the energy amplification time and the optimum amplification time, and the amplitude time from the impedance change point to the next change point is measured based on the impedance detection signal. The liquid level amplitude time measuring means; and the second determining means having an amplitude time error calculating means for calculating an error between the liquid level amplitude time measured by the liquid level amplitude time measuring means and the optimum amplitude time,
The drive control means lowers the frequency of the high frequency drive signal of the high frequency drive means when the determination result of the first determination means is shorter than the optimum amplification time, and the high frequency drive means when the determination result is longer than the optimum amplification time. Frequency control means for increasing the frequency of the high frequency drive signal, and the drive voltage of the high frequency drive means is increased when the result of the determination by the second determination means is shorter than the optimum amplitude time. When the amplitude time error is outside the permissible range, the amplitude time error is supplied to the temperature control means. When the amplitude time error is within the allowable range, and the amplification time error is outside the allowable range, the amplification error time is supplied to the frequency control means,
The droplet ejection recording apparatus according to claim 1 or 2, further comprising a selection unit that supplies the amplitude time error to the amplitude control unit when the amplification time error is within an allowable range. 12. An ultrasonic lens generated on the acoustic lens is recorded by disposing an acoustic lens disposed on the upper surface of the piezoelectric element in a recording liquid storage section and driving the piezoelectric element at high frequency by a high frequency drive means. In a method of driving a droplet jet recording apparatus that converges on a surface of a recording liquid in a liquid storage portion and causes recording droplets to fly, a step of driving the piezoelectric element by the high frequency driving means, and a driving state of the piezoelectric element. To detect the impedance of the drive system including the piezoelectric element, to determine whether the ultrasonic energy is appropriate based on the detected impedance, and to determine whether the ultrasonic energy is appropriate. And a step of controlling the recording liquid temperature based on the determination result. 13. An ultrasonic lens generated on the acoustic lens is recorded by disposing an acoustic lens disposed on the upper surface of a piezoelectric element in a recording liquid storage section and driving the piezoelectric element at a high frequency by a high frequency drive means. In a method of driving a droplet jet recording apparatus that converges on a surface of a recording liquid in a liquid storage portion and causes recording droplets to fly, a step of driving the piezoelectric element by the high frequency driving means, and a driving state of the piezoelectric element. At the step of detecting the impedance of the drive system including the piezoelectric element, a step of determining whether or not the ultrasonic energy is appropriate based on the detected impedance, and the determination result of the step is that the ultrasonic energy is appropriate. If not, after the step of controlling the recording liquid temperature, and after the ultrasonic energy becomes a proper state by the control of the recording liquid temperature,
And a step of controlling the frequency of the high-frequency driving means based on the result of the determination as to whether or not the ultrasonic energy is appropriate. 14. An ultrasonic lens generated on the acoustic lens is recorded by disposing an acoustic lens disposed on the upper surface of the piezoelectric element in a recording liquid storage section and driving the piezoelectric element at a high frequency by a high frequency drive means. In a method of driving a droplet jet recording apparatus that converges on a surface of a recording liquid in a liquid storage portion and causes recording droplets to fly, a step of driving the piezoelectric element by the high frequency driving means, and a driving state of the piezoelectric element. In the step of detecting the impedance of the drive system including the piezoelectric element, the impedance change time from the start of driving to the change point of the impedance is measured based on the detected impedance, and the liquid surface of the drive focal length is measured based on the impedance change time. And the sound pressure are in a proper positional relationship, and ultrasonic energy is generated by the standing wave in the recording liquid generated between the liquid surface of the recording liquid and the acoustic lens. A liquid comprising: a step of judging whether or not it is properly accumulated / amplified, and a step of controlling a recording liquid temperature based on a judgment result of whether or not ultrasonic energy is proper. Driving method of droplet ejection recording apparatus. 15. An ultrasonic lens generated on the acoustic lens is recorded by arranging an acoustic lens disposed on the upper surface of the piezoelectric element in a recording liquid storage portion and driving the piezoelectric element at a high frequency by a high frequency drive means. In a driving method of a droplet jet recording apparatus in which recording liquid droplets are made to fly by being converged on a recording liquid surface of a liquid storage portion, a driving system including the piezoelectric element by driving the piezoelectric element by the high frequency driving means. The impedance is detected, the energy amplification time from the drive start to the impedance change point is measured based on the detected impedance, and the positional relationship between the liquid surface of the drive focal length and the sound pressure is appropriate based on the energy amplification time, Ultrasonic energy that determines whether or not the ultrasonic energy is properly accumulated and amplified by the standing waves in the recording liquid generated between the liquid surface of the recording liquid and the acoustic lens. A determination step, and a temperature control step of controlling the recording liquid temperature when the ultrasonic energy is not appropriate as the determination result of the ultrasonic energy determination step,
After the ultrasonic energy is brought into a proper state by controlling the recording liquid temperature in the temperature control step, the ultrasonic energy determination step is executed again and the high frequency is determined based on the determination result of whether the ultrasonic energy is proper or not. And a frequency control step of controlling the frequency of the driving means, and the method is repeatedly performed. 16. An ultrasonic lens generated on the acoustic lens is recorded by disposing an acoustic lens disposed on the upper surface of the piezoelectric element in a recording liquid storage section and driving the piezoelectric element at high frequency by a high frequency drive means. In a method of driving a droplet jet recording apparatus that converges on a surface of a recording liquid in a liquid storage portion and causes recording droplets to fly, a step of driving the piezoelectric element by the high frequency driving means, and a driving state of the piezoelectric element. The step of detecting the impedance of the drive system including the piezoelectric element and the amplitude time from the change point of the impedance to the next change point are measured, and the viscosity of the recording liquid is appropriate, and it occurs between the liquid surface of the recording liquid and the acoustic lens. The step of determining whether or not the ultrasonic energy is properly accumulated and amplified by the standing wave in the recording liquid, and the determination result of whether or not the ultrasonic energy is appropriate. And a step of controlling the temperature of the recording liquid based on the above. 17. An acoustic lens disposed on the upper surface of a piezoelectric element is disposed in a recording liquid storage section, and the piezoelectric element is driven at a high frequency by a high frequency driving means to record an ultrasonic wave generated from the acoustic lens. In a driving method of a droplet jet recording apparatus in which recording liquid droplets are made to fly by being converged on a recording liquid surface of a liquid storage portion, a driving system including the piezoelectric element by driving the piezoelectric element by the high frequency driving means. The impedance is detected, the amplitude time from the point of change of impedance to the next point of change is measured based on the detected impedance, the viscosity of the recording liquid is appropriate, and the recording liquid is generated between the liquid surface of the recording liquid and the acoustic lens. Ultrasonic energy determination step for determining whether or not the ultrasonic energy is properly accumulated / amplified by the standing wave of, and the determination result of the ultrasonic energy determination step Is a temperature control step for controlling the recording liquid temperature when the energy of the ultrasonic wave is not appropriate, and the ultrasonic energy determination step is performed after the ultrasonic energy is brought into an appropriate state by controlling the recording liquid temperature in the temperature control step. And an amplitude control step of controlling the amplitude of the high-frequency driving means based on the result of the determination of whether the ultrasonic energy is proper or not, and the droplet control method. Driving method of jet recording apparatus. 18. An ultrasonic lens generated by the acoustic lens is recorded by disposing an acoustic lens disposed on the upper surface of the piezoelectric element in a recording liquid storage section and driving the piezoelectric element at high frequency by a high frequency drive means. In a method of driving a droplet jet recording apparatus that converges on a surface of a recording liquid in a liquid storage portion and causes recording droplets to fly, a drive system including the piezoelectric element is driven by the high-frequency drive unit. The impedance is detected, the amplitude time from the change point of the detected impedance to the next change point is measured, the viscosity of the recording liquid is proper, and the standing wave in the recording liquid generated between the liquid surface of the recording liquid and the acoustic lens is measured. The ultrasonic energy determination step for viscosity determination for determining whether or not the ultrasonic energy is appropriately accumulated / amplified, and the determination result of the step is that the ultrasonic energy is not appropriate. First, a temperature control step of controlling the temperature of the recording liquid, and after the ultrasonic energy is brought into a proper state by controlling the temperature of the recording liquid in the temperature control step, the piezoelectric element is driven by the high frequency driving means. The impedance of the drive system including is detected, the energy amplification time from the drive start to the change point of the impedance is measured based on the detected impedance, and the liquid surface of the driving focal length and the position of the sound pressure are measured based on the energy amplification time. Ultrasonic energy determination step for liquid level position to determine whether the relationship is proper and ultrasonic energy is properly accumulated / amplified by the standing wave in the recording liquid generated between the recording liquid surface and the acoustic lens And a frequency control step of controlling the frequency of the high frequency drive means based on the determination result of whether or not the ultrasonic energy in the step is appropriate, After the ultrasonic wave energy is brought into a proper state by controlling the wave number, the viscosity ultrasonic wave energy judging step is executed again, and the high frequency driving means of the high frequency driving means is judged based on the judgment result as to whether or not the ultrasonic wave energy is proper. A method of driving a droplet jet recording apparatus, which comprises repeatedly performing an amplitude control step of controlling an amplitude.