JPH03272854A - Temperature compensating method for ink jet recorder - Google Patents

Abstract

PURPOSE:To make it possible to drive a piezoelectric element most suitably corresponding with changes of the ink viscosity in any change of ambient temperature so as to realize a constantly uniform recording by providing thermal resistance elements adjacent to ink pressure chambers and utilizing the thermal resistance element as a discharge resistance element of the piezoelectric element. CONSTITUTION:Thermal resistance elements 15-1 through 15-n and resistance elements 14-1 through 14-n are connected to each other. The thermal resistance elements 15-1 through 15-n are the elements provided adjacent to ink pressure chambers 10-1 through 10-n, where a positive temperature coefficient thermistor is used for the thermal resistance element. The resistance elements 14-1 through 14-n are resistances for correcting a temperature characteristic and are set properly so as to obtain a desired combined resistance. When the temperature is low, a drive voltage of the piezoelectric element is increased in accordance with an increase of the ink viscosity, and when the temperature is high, the drive voltage of the piezoelectric element is reduced in accordance with a decrease of the ink viscosity so that an ink of fixed quantity can be injected constantly and recording with high uniformity can be achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a temperature compensation system for an inkjet recording apparatus that records by ejecting ink droplets.

[Conventional technology]

First, the operating principle of the inkjet recording head will be explained.

Figure 2 shows an example of an inkjet recording head that performs recording by applying a driving pulse to a piezoelectric element f installed on the wall of an ink pressurizing chamber and ejecting ink droplets from a nozzle. be. In Fig. 2, 13 is an ink tank, 10 is an ink pressurizing chamber communicating with the ink tank, 4 is a piezoelectric element, 12 is a diaphragm, 11 is a nozzle, and Fig. 3 is a drive circuit for the inkjet recording head. be. FIGS. 4(a) to 4(e) show the turbulence timing chart 1 and drive voltage waveform of the inkjet recording head labeled L. The operation of the ink cartridge 1 recording head will be explained with reference to FIGS. 2, 3, and 4. Before time t in FIG. 4, transistor 7,
Transistor 6 and transistor 5 are in an off state,
The piezoelectric element 4 is charged to approximately voltage 5 (when the power of the recording apparatus is turned on, as an initial operation, the transistor 6 is turned on Bk and charging is performed via the charging resistance element 2). This state is the standby state. The resistance value of charging resistor element 2 (R,) and discharging resistor element 3 (R,) in Fig. 3 is R
, <<Rb and zr. Time tic: The signal shown in FIG. 4(a) is applied to the terminal a, and the transistor 5 is turned on.The electric charge of the piezoelectric element 4 is discharged through the discharge resistor element 3 (R5), and the piezoelectric element 4 is turned on. Gradually move outward to the 7th position. At the time t2 after a predetermined period of time has elapsed, the transistor 5 is turned off (Fig. 4 (1)).
By applying a signal to the terminal 4 to turn on the transistor 7, the transistor 6 turns on, and the piezoelectric element 'E'-4 is connected to the charging resistance element 2 (R,) through the charging resistance element 2 (2').
．． When the battery is charged, the capacity of the ink pressurizing chamber 10 decreases, and ink droplets are ejected from the nozzle 11.
[N1. of type element 4] The dynamic voltage waveform is shown. The falling curve in Figure 4 (C) shows the capacitance of the piezoelectric layer 7-4 and the discharge resistance element 3.
The rise curve is determined by the capacitance of the piezoelectric element 4 and the energization time (T2) of the charging resistance element 2 and the transistor 6, and the actual piezoelectric Drive voltage of the element (Fig. 4 (
■I) shown in e) is decisive, and is set so that desired injection characteristics can be obtained.

FIG. 5 shows a plurality of inkjet recording beds B.
I=j, there is an example of a multi-nozzle on-demand type inkjet recording device that performs recording in a dot matrix by ejecting ink droplets as appropriate according to the printing pattern (,7), and FIG. 6 shows the drive circuit thereof. It is a diagram showing the sixth
The figure shows a multi-nozzle version of the drive circuit shown in FIG. 3 (Q), in which discharge circuits corresponding to the number of nozzles are configured.

However, the charging circuit has one :) common to all nozzles, and diodes l-1-1-n corresponding to the number of nozzles are added. Here, terminal a + ”-a n in Fig. 6
By adding the I print command, the piezoelectric element f4・-1～
4-n is selectively driven to eject ink droplets.

Now, -G+: The viscosity of ink in inkjet recording changes greatly with temperature change 1, which affects the particle size and flight speed of ejected ink droplets and causes disturbances in recording quality.

Conventionally, in addition to such an ink viscosity σ) temperature compensation method, a method has been proposed in which the ink is heated to a constant temperature, as disclosed in Japanese Patent Application Laid-Open No. 53-84729. Another temperature compensation method is disclosed in Japanese Patent Application Laid-Open No. 55-65566, in which the surrounding atmospheric temperature is determined by a heat-sensitive resistor element f.
A method has been proposed in which the magnitude of the drive voltage of the piezoelectric accumulator f is changed by detecting the f.

[Problem to be solved by the invention]

However, in general, the operating temperature of inkjet recording devices1.
tO'C - 40°C and wide range 1. In the method described above that heats the ink to a constant temperature, the set temperature must be set at 40°C to keep the ink temperature constant within these ranges.
It must be more than that. However, ink is generally heated to high temperatures, which causes phenomena such as bleeding, which deteriorates recording quality. Furthermore, the higher the set temperature, the more a large-capacity heat source is required for heating, and the thermal inertia of the heat source reduces control accuracy and causes variations in viscosity, making it impossible to maintain uniform recording quality.

In addition, in a method that changes the magnitude of the drive voltage of the piezoelectric element by detecting the surrounding atmospheric temperature with a heat-sensitive resistance element, etc.,
Inkjet recording apparatus 1 equipped with multiple nozzles has a complicated power supply circuit, and the temperature distribution in the ink adding chamber corresponding to i is U, so the surrounding atmospheric temperature is detected (driving voltage Even if the correction is increased, it is not possible to expect compensation of 1-min.

One object of the present invention is to provide a temperature compensation system for an inkjet recording apparatus that eliminates the above-mentioned drawbacks and has uniform recording quality over a wide temperature range.

[Means to solve the problem]

The temperature compensation method of the Infusiera 1-recording device of the present invention is as follows:
Using ink whose viscosity changes depending on the temperature, there is an ink pressure chamber that stores the ink to be ejected, and an ink chamber (two communicating nozzles, and a piezoelectric element to adjust the fluid pressure in the ink pressure chamber according to the printing designation. In the temperature compensation system of a multi-nozzle on-demand type inkjet recording device that has multiple sets of drive mechanisms that eject droplets from high nozzles, a heat-sensitive resistance element is installed near the ink pressurizing chamber, and the piezoelectric element is The discharge resistor element "f-ε" is characterized by using this heat-sensitive resistor element.

(Function) According to the present invention, it is possible to optimally drive the piezoelectric element according to the protection of the ink even under any change in the ambient temperature of the inkjet recording apparatus, and uniform recording can always be achieved.

(Examples) Hereinafter, the present invention will be explained in detail using examples not shown in the drawings.

FIG. 7 shows the structure of a single ink cartridge recording head used in the present invention, and FIG. 8 shows the structure of a multi-nozzle inkjet recording apparatus. 15 and 8 in Figure 7
15-1 to 15-I] in the figure are the ink pressurizing chamber 10 in FIG. 7 and the ink pressurizing chamber 10-1-:1.0- in FIG.
Near n (,: installed closely thermally to detect the temperature of ink): is a heat-sensitive resistance element.

The structure of the inkjet recording apparatus of the present invention differs from the conventional example shown in FIGS. 2 and 5 only by adding this heat-sensitive resistance element. Therefore, the operation regarding ink ejection is exactly the same as that described above.

FIG. 1 is a circuit diagram showing one embodiment of the present invention. In contrast to the conventional example shown in FIG. 6, heat-sensitive resistance elements 1.5-1-, 15-n and resistance elements 14 = ] to 14-n are connected instead of discharge resistance elements 3-1-3-n. There is. Here, the thermal paper 4/'L elements f15-1 to 15-n are heat-sensitive resistance elements installed near the ink pressurizing chambers 10.10-1 to 10-n shown in Figure 7 and No. 8. be. As a heat-sensitive resistance element,
Figure 9 shows the temperature characteristics. Resistance Elements] 4-1 to 14-n are resistances for correcting temperature characteristics, and are appropriately set so as to obtain a desired combined resistance. FIG. 10 shows the combined resistance value as a function of temperature.

Here, the driving of the piezoelectric element 4-1 will be explained. piezoelectric element f-
4-2 to 4-n are driven in exactly the same manner. 1st
Detected temperature 1 when the signals shown in the timing charts of Fig. 11 (wa) and (b) are applied to terminal a of the circuit shown in the figure.
FIG. 11(C) and FIG. 11(d) show the drive voltage waveforms of the piezoelectric element 4-1 in the case of 1' and the detection mixed coal 1'. When the detection temperature T (low temperature) is detected, a discharge occurs through the combined resistance RT shown in FIG.
As shown in Figure (C), the voltage applied to the piezoelectric element 4-1 is T
becomes qualitatively larger (FIG. 11 V, i::” (display)).

When the force detection temperature is 1, (high temperature), the combined resistance RTb becomes larger than RT, I as shown in the 10th garden, so the voltage applied to the piezoelectric element 4-1 becomes substantially smaller (1st
(Displayed in Figure 1 ■2). In this way (at low temperatures T, the piezoelectric element driving voltage is substantially increased according to the viscosity of the ink, and at high temperatures 1-5, the piezoelectric element driving voltage is increased according to the viscosity of the ink). By substantially lowering the driving voltage, a constant amount of ink can be ejected at all times, and highly uniform recording can be achieved.

A heat-sensitive resistance element is installed near each nozzle (...: each corresponding ink pressurizing chamber. This allows the ink temperature to be reliably detected regardless of any temperature distribution or sudden temperature change, and changes in ink viscosity. Accordingly, it is possible to optimally drive the famous piezoelectric element in 7-output mode.

Note that heat-sensitive resistance elements 5-1 to 15-n and resistance element-1
By selecting 4-1 to 4-2 according to the characteristics of the ink's viscosity change with respect to temperature, the desired jetting characteristics can be obtained even when applied to ink having various temperature characteristics.

〔Effect of the invention〕

According to the present invention, as described above, it is possible to provide an inkjet recording device that reliably performs optimal temperature compensation with a simple configuration and has high print quality.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. FIG. 2 is a sectional view showing an example of a conventional one-tank construction of an inkjet recording head. FIG. 3 is a circuit diagram showing a conventional driving method for an inkjet recording head. FIG. 4 is a diagram showing the drive timing 1 of the drive timing 1 of the inkjet head ε self-recording. FIG. 5 is a diagram showing the structure of a conventional example of a multi-nozzle on-demand type inkjet recording device. FIG. 7 is a circuit diagram showing a conventional example of a driving method of a sixth intermittent multi-nozzle on-demand inkjet recording device. FIG. 7 is a diagram showing an inkjet recording head according to an embodiment of the present invention. FIG. 8 is a structural diagram of an ink jet recording apparatus according to an embodiment of the present invention. FIG. 9 is a diagram showing the temperature characteristics of a heat-sensitive resistance element used in an embodiment of the present invention. FIG. 10 is a diagram showing the combined resistance of the heat-sensitive resistance element ε resistance element used in one embodiment of the present invention. FIG. 11 is a diagram showing drive timing and drive voltage waveforms in one embodiment of the present invention. 1.1-1.1-2.1-0...Resistance element 2.2-1
．． 2-2.2- n-resistance f! , -j-3... Resistance element 4.4-1.4-2.4-n... Piezoelectric element 5.5-1
．． 5-2.5-n...Transistor 6...Transistor 7...Transistor 8...Drive power supply unit 9...Inkjet recording head 10.10-1, ], O-n-Ink addition Jf Room 11
．． 11-1.11-n... Nozzle 12... Vibration plate 13... Ink tank 14.14-1, ]4-2.14-n... Resistance element 1
5.15-1, ]5-2.15-・n...Heat-sensitive resistance element f-

Claims (1)

[Claims] An ink pressurizing chamber that stores ink to be ejected using ink whose viscosity changes depending on temperature, a nozzle communicating with the ink pressurizing chamber, and an ink pressurizing chamber that charges and discharges a piezoelectric element according to a printing command. A multi-nozzle system having multiple sets of drive mechanisms that increase the liquid pressure and eject ink droplets from the nozzles.
An inkjet recording characterized in that, in a temperature compensation system of an on-demand type inkjet recording device, a heat-sensitive resistance element is installed near the ink pressurizing chamber, and the heat-sensitive resistance element is used as a discharge resistance element of the piezoelectric element. Equipment temperature compensation method.