Driving method for ink jet head

[Detailed Description of the Invention]

Field of the Invention The present invention relates to the drive system of the ink jet head of an ink-on Daimant method. PRIOR ART in recent years, the demand of improvement in the speed of a printer, noise reduction, colorization, etc. increases, and an ink-jet printer attracts attention -- as (it came and came.) Hereinafter, the drive system of the conventional ink jet head is explained. Drawing 5 is an outline perspective view of the conventional ink jet head. It is a silicon substrate which pastes 29 together to a glass board, pastes 30 together to glass board 29, and forms an ink channel. These are formed in silicon base 30 at the nozzle for 31 to spout ink and the pressurization room where 32 was provided in the inflow mouth side of nozzle 31. The ink way where 33 supplies ink to a pressurization room, and 1 are the piezo-electric elements stuck on the flexible plate which constitutes a part of pressurization room 32. Drawing 6 is a block diagram of a piezo-electric element drive. 34 is a piezo-electric element drive which drives piezo-electric element 1. It is a diode with which 35 which constitutes piezo-electric element drive 34 pours a piezo-electric element charge resistor, 36 passes P channel type electric field effect Transis evening for piezo-electric element charge, and 37 sends piezo-electric element charging current, It is a diode with which 38 pours a piezo-electric element discharging resistor, 39 passes N channel type field effect transistor for piezo-electric element electric discharge, and 40 sends piezo-electric element discharge current. The piezo-electric element drive signal generation device which generates a signal for 2 to drive piezo-electric element 1, and 3 are power supplies which drive piezo-electric element 1. The operation is explained below about the drive system of the ink jet head constituted as mentioned above. Drawing 7 (a) is in the state where voltage is not added to piezo-electric element 1, the ink jet head is a waiting state, the pressurization interior of a room was full of ink via ink way 33, and the ink meniscus at the tip of nozzle 31 has become depressed in the concave with the surface tension of ink. First like [ the piezo-electric element drive signal of piezo-electric element drive signal generation device 2 / of Drawing 8 (a) ], If it changes to H signal from L, P channel type field effect transistor 36 for piezo-electric element charge of piezo-electric element drive 34 will be set to ON, and N channel type field effect transistor 39 for piezo-electric element electric discharge will be come by off. Therefore, it lets piezo-electric element charge resistor 35 and diode 37 pass, and charging current flows into piezo-electric element 1 from power supply 3, and the amount of displacement of piezo-electric element 1 is displaced as shown in Drawing 8 (c). Since it is displaced as the wall surface of pressurization room 32 is shown in Drawing 7 (b) by modification of this piezo-electric element 1, by this displacement, the capacity of pressurization room 32 changes, the ink meniscus at the tip of nozzle 31 expands to convex, and ink blows off from nozzle 31. Next, if a piezo-electric element drive signal changes from H to L, P channel type field effect transistor 36 for piezo-electric element charge will be come by off, and N channel type field effect transistor 39 for piezo-electric element electric discharge will be set to ON. Therefore, piezo-electric element discharge current flows through diode 40 and piezo-electric element discharging resistor 38, and piezo-electric element 1 is displaced as shown in Drawing 8 (c). this shows in Drawing 7 (c) -- the capacity of pressurization room 32 returns to the same state as Drawing 7 (a) like, ink is supplied to pressurization room 32 through ink way 33, and the ink meniscus at nozzle 31 tip becomes depressed in a concave again. Object of the Invention However, when the capacity of a pressurization room tends to be changed quickly and it is going to increase ink jet energy by charging quickly in the above-mentioned conventional composition to the piezo-electric element which is an actuator, Dumping vibration of a piezo-electric element occurs, the small ink droplet which is not needed by this vibration blows off, and unnecessary A pot occurs in space, since the displacement speed of an actuator is very quick, until ink meniscus becomes unstable and performs the next ink jet at the time of ink supply -- l This -- enough -- time must be taken. For this reason, when the drive frequency of the piezo-electric element drive signal was raised and high-speed printing was performed, the printing quality of an ink jet printer had the fault of falling remarkably. Means for solving problem The driving means which drives a piezoelectric element in order that the present invention may solve the above-mentioned problem, It has a detection means to detect the electric capacity of a piezoelectric element, and a control means which controls a piezoelectric element, and makes it change the waveform of the piezoelectric element drive signal which detected the electric capacity of the piezoelectric element by the detection means, and was outputted from the driving means according to the detected electric capacity by a control means. OPERATION The present invention is the amount of displacement of a piezoelectric element by detecting the electric capacity of the piezoelectric element which is an actuator, and applying feedback by the above-mentioned composition, - Hui - Displacement speed is controllable, while Doppatsuku(ing) and suppressing dumping vibration of an actuator. EXAMPLE Drawing 1 shows the block diagram of AJ in one example of the present invention, and a A element drive controlling device. In Drawing 1, as for 1, a piezo-electric element drive signal generation device and 3 are power supplies a piezo-electric element and 2, and since these are the same as the composition of the conventional example shown in Drawing 6, they omit detailed explanation. 4 is a control circuit which controls piezo-electric element l by the piezo-electric element drive signal outputted from piezo-electric element drive signal generation device 2. 5 is an electric capacity detector circuit, detects the amount of change of the electric capacity of piezo-electric element 1 by displacement of piezo-electric element 1, and changes it into voltage. 6 is the amount conversion circuit of displacement, and changes and outputs the output voltage of electric capacity detector circuit 5 to the voltage proportional to the amount of displacement of piezo-electric element 1. Drawing 2 is a circuit diagram of control circuit 4 of Drawing 1, and the amount conversion circuit 6 of displacement. A charge resistor for 7 to charge a capacitor and for 8 charge capacitor 7 in subI11 circuit 4, first, A discharging resistor for the diode with which 9 sends the charging current of capacitor 7, and 10 to discharge capacitor 7, and 11 are the diodes which send the discharge current of capacitor 7, A Piezo displacement command signal is generated with these capacitors 7, charge resistor 8, diode 9, discharging resistor 10, and diode 11. 12 outputs the Piezo displacement command signal inputted by the operational amplifier which constitutes voltage 7 Oroa by low impedance. 13 constitutes the reversal amplification circuit from an operational amplifier with resistor 14.15 and semipermanent resistor 16, and amplifies the Piezo displacement command signal outputted from operational amplifier 12. 17 is P channel type field effect transistor, and 18 is N channel type field effect transistor, This P channel type field effect transistor 17 and N channel type field effect transistor 18 constitute a complimentary amplification circuit, and it generates the drive voltage of piezo-electric element 1 with the Piezo displacement command signal amplified by operational amplifier 13. Next, in the amount conversion circuit 6 of displacement, 19 constitutes the reversal amplification circuit from an operational amplifier with resistor 20 and semipermanent resistor 21 nonlinear element 22, and changes an electric capacity detection signal into the amount signal of displacement. 23 is a phase compensation circuit for uniting the phase of the above-mentioned amount signal of displacement with the phase of the Piezo displacement command signal which is an output signal of operational amplifier 12. 24 constitutes the differential amplifier circuit from an operational amplifier with resistor 25.26.27.28, and outputs the error signal which is a difference of the amount signal of displacement which is an output signal of phase compensation circuit 23, and the Piezo displacement command signal which is output signals of operational amplifier 12. This output is connected to the non-inversed input terminal of operational amplifier 13 through semipermanent resistor 16. The operation is explained below about the drive system of the ink jet head constituted as mentioned above. First, if it becomes H signal as the piezo-electric element drive signal from piezo-electric element drive signal generation device 2 shows in the timing chart figure of Drawing 3 (a), as for a signal, an electric charge will be charged through resistor 8 for charge, and diode 9 at capacitor 7. Next, if a piezo-electric element drive signal turns into L signal, the electric charge accumulated in capacitor 7 through diode 11 and resistor 10 for electric discharge will be discharged. The voltage which appears in the both ends of this capacitor 7 is outputted as low impedance shows to Drawing 3 (b) by operational amplifier 12 which constitutes the voltage follower, and it serves as a Piezo displacement command signal. After this Piezo displacement command signal was amplified by the reversal amplification circuit which comprises resistor 14.15, semipermanent resistor 16, and operational amplifier 13, It is outputted to piezo-electric element 1 by the complimentary amplification circuit which comprises P channel type field effect transistor 17 and N channel type field effect transistor 18. When a piezo-electric element is displaced, its board thickness cringes and it has the character in which electric capacity becomes large. The change of electric capacity to the amount of displacement of a 3X3X0.2-mm piezo-electric element general in Drawing 4 is shown. Since thickness becomes thin as a piezo-electric element is displaced, electric capacity becomes large. After using this character of a piezo-electric element and changing electric capacity change of a piezo-electric element into voltage change by electric capacity detector circuit 5, it has changed by the amount conversion circuit 6 of displacement so that the output voltage to the amount of displacement may become proportionally. The amount conversion circuit 6 of displacement changes an electric capacity signal into the amount signal of displacement by operational amplifier 19, resistor 20, and nonlinear element 22, and adjusts the offset voltage to the amount of displacement with semipermanent resistor 21. After the amount signal of displacement outputted here unites the Piezo displacement command signal and phase which are the output signals of operational amplifier 12 which constitutes a voltage follower by phase compensation circuit 23, it lets resistor 26 pass and is inputted into the non-inversed input terminal of operational amplifier 24. Operational amplifier 24 constitutes the differential amplifier circuit in combination with resistor 25.26.27.28, The error signal shown in Drawing 3 (d) which is a difference of a signal with the Piezo displacement command signal which is an output signal of operational amplifier 12 which constitutes the voltage follower shown in the amount signal of Piezo displacement which is an output of phase compensation circuit 23 shown in Drawing 3 (C), and Drawing 3 (b) is outputted. Human power of this error signal is carried out through semipermanent resistor 16 to the non-inversed input terminal of operational amplifier 13 which constitutes an inverting amplifier, to piezo-electric element drive voltage, feedback is applied so that the amount of displacement of piezo-electric element 1 may follow a Piezo displacement command value, and Piezo drive voltage comes to be shown in Drawing 3 (e). as mentioned above, the thing for which the amount of displacement of a piezo-electric element is detected as change of the electric capacity of the piezo-electric element itself, and it changes and takes out on voltage, and applies feedback to a Piezo displacement command signal -- a A bush element -- as the actuator of an ink jet head -- accuracy (it is controllable.) EFFECT OF THE INVENTION The driving means in which the present invention drives a piezoelectric element as mentioned above, and a detection means to detect the electric capacity of a piezoelectric element, It was made to change the waveform of the piezoelectric element drive signal which was provided with the control means which controls a piezoelectric element, detected the electric capacity of the piezoelectric element by the detection means, and was outputted from the driving means according to the detected electric capacity by a control means. The displacement of a piezoelectric element itself can be fed back, change of a piezoelectric element can be controlled, and displacement speed can be controlled while suppressing dumping vibration of an actuator, Generating of unnecessary A pot can be suppressed, ink meniscus can be stabilized for a short time, and even if it raises the drive frequency of a piezoelectric element compared with the former, high-definition high-speed printing can be performed.

[Brief Description of the Drawings]

Drawing 1 is a block diagram of the piezo-electric element drive controlling device in one example of the present invention, Drawing 2 is a circuit diagram of a piezo-electric element drive controlling device, and Drawing 3 is a timing diagram of a piezo-electric element drive controlling device, In the outline perspective view of the ink jet head of a conventional example, and title 6 figure, the figure of an ink jet head of operation and Drawing 8 of the circuit diagram of the piezo-electric element drive of a conventional example and Drawing 7 are [ the change figure of electric capacity / as opposed to the amount of displacement of a piezo-electric element in Drawing 4 /, and Drawing 5 ] timing diagrams of the piezo-electric element drive of a conventional example. 1 ... Piezo-electric element 2 ... Piezo-electric element drive signal generation device 3 ... Power supply 4 [ ... Capacitor ] ... Control circuit 5 ... Electric capacity detector circuit 6 ... The amount conversion circuit 7 of displacement 8 ... Charge resistor 9 ... Diode 10 ... Discharging resistor 11 ... Diode 12 ... Operational amplifier 13 ... Operational amplifier 14 ... Resistor 15 ... Resistor 16 [ ... Operational amplifier ] ... Semipermanent resistor 17 ... P channel type field effect transistor 18 ... N channel type field effect transistor 19 20 ... resistor 21 ... semipermanent resistor 22 ... nonlinear element 23 ... phase compensator 24 ... operational amplifier 25 ... resistor 26 ... resistor 27 ... resistor 28 ... Drawing 1 of resistor 1: -- piezo-electric element 2: Piezo-electric Element Drive Signal Generation Device 3 : Power Supply 4: Control Circuit 5: Electric Capacity Detector Circuit 6: Amount Conversion Circuit of Displacement The 3 Figure The Figure 000 1010 1020 Electric capacity (PF) The 5 Figure The A Figure (a) 2 (b) (C)