CN1672933A - Microfluid ejection device and method for improving microfluid ejection quality - Google Patents

Abstract

The invention provides a micro-fluid ejecting device and a method for improving the micro-fluid ejecting quality. The resistance value of the heating device in the micro-fluid ejecting device is detected by a resistance measuring device (resistor sensing unit). And a signal control unit (signal control unit) is used to adjust and output the driving signal according to the detection result. Thereby improving the quality of the micro-fluid ejection or improving the performance of the micro-fluid ejection device.

Description

Microfluid ejection device and method for improving microfluid ejection quality

technical field

The present invention relates to a micro-fluid ejection device and a method for improving the quality of micro-fluid ejection, in particular to a method for detecting the resistance value of a heating device in a micro-fluid ejection device and adjusting the output drive signal to improve the quality of micro-fluid ejection Methods.

Background technique

At present, fluid ejection devices are mostly used in components such as inkjet heads and fuel injectors, among which inkjet heads are mostly designed with thermal bubble driving.

Fig. 1 shows a kind of traditional U.S. Patent 6,102,530 single-substrate fluid ejection device 1, and it uses a silicon substrate 10 as body, and forms a structural layer 12 on silicon substrate 10, and silicon substrate 10 and structural layer 12 A fluid cavity 14 is formed between them to accommodate the fluid 26; and a first heater 20 and a second heater 22 are arranged on the structural layer 12, and the first heater 20 is used to generate a first heater 22 in the fluid cavity 14. A bubble 30 , the second heater 22 is used to generate a second bubble 32 in the fluid cavity 14 to eject the fluid 26 in the fluid cavity 14 .

Because the single-substrate fluid ejection device 1 has the design of virtual valve (virtual valve), and has the characteristics of high arrangement density, low interaction interference, and low heat loss, and does not need to use the assembly method to join the nozzle orifice sheet, it can reduce Cost of production.

However, the single-substrate fluid ejection device 1 has relatively strict requirements on heater resistance. In the resistive layer process in the previous process, there may be a considerable gap in the resistance value of each heater in the same inkjet chip, which exceeds the manufacturing specification, which affects the ejection quality of the microfluidic device and leads to a decrease in the manufacturing yield.

Please refer to FIG. 2 , after receiving and processing printing data, a controller sends a printing control signal to an inkjet head driving circuit. A control voltage power supply provides a control voltage Vs to the inkjet head driving circuit, and the magnitude of the control voltage Vs is controlled by the control voltage power supply. The inkjet head driving circuit controlled by the controller provides a driving voltage pulse VP to the heater resistor of a thermally driven inkjet head for fluid ejection. U.S. Patent No. 5,526,027 discloses a fluid ejection device, which uses the temperature sensing resistor of the inkjet chip as a reference value for the resistance of each heater in the inkjet chip, and then optimizes the jetting of the chip. Ink condition setting.

The single-substrate fluid ejection device of US Patent No. 6,244,682 uses an optical scanning mechanism to perform optical detection on the printed graphic results of the inkjet chip. And use the above detection results to compare with the original set printing conditions, as the setting and calibration standard of the best inkjet conditions.

From a technical point of view, in the scope of the above-mentioned traditional technologies, it is assumed that the resistance values of all heating elements in the inkjet chip are within a specific resistance value range, and the inkjet conditions are adjusted. In fact, the heaters in the inkjet chip may have different resistance values due to process factors. After a period of use, the printing defects caused by the differences in the resistance values of the heating elements will become more and more obvious. , leading to a decrease in print quality.

Invention content:

In view of this, the object of the present invention is to measure the resistance value range of each heater in the inkjet chip, compare the detection result of the resistance value of the heater with the standard operating resistance value, and adjust the output driving signal as a whole or individually. in accordance with.

According to the above purpose, the present invention provides a method for improving the quality of microfluid ejection, comprising the following steps: providing a microfluid ejection device having at least one set of heaters for fluid heating, and nozzle holes corresponding to the heaters. By means of a heater detection device, the resistance value of the heater is detected, and the detection result of the resistance value of the heater is compared with the standard operation resistance value. And when the detected resistance value is higher than the standard operating resistance value, a signal control component is used to adjust and output drive signals to all heating elements in the microfluid ejection device, so as to improve the microfluid ejection quality.

According to the above object, the present invention provides a method for improving the quality of microfluid ejection, comprising the following steps: providing a microfluid ejection device with at least one set of heaters for fluid heating, and nozzle holes corresponding to the heaters, by The resistance value of each of the heaters is detected by a heater detection device, and the detection result of the resistance value of each of the heaters is compared with a standard operating resistance value. and using a signal control component to output an adjustment drive signal to the heater whose resistance value is higher than the standard resistance value, and to maintain the original standard operation drive signal for the heater whose resistance value is equal to the standard resistance value to improve micro Fluid jet quality.

According to the above purpose, the present invention provides a microfluid ejection device, comprising at least one heater capable of heating the fluid, a heater detection device electrically connected to the heater to detect the resistance value of the heater, a a comparator for comparing the detection result of the resistance value of the heater with a standard operating resistance value, and a signal control device for providing adjusted driving when the resistance value of the heater is higher than the standard operating resistance value A signal is input to the heater.

The present invention will be described in more detail below in conjunction with the accompanying drawings and preferred embodiments.

Description of drawings

1 is a schematic diagram of a conventional single-substrate fluid ejection device;

Fig. 2 is a schematic block diagram of a conventional fluid ejection device;

Figure 3 is a schematic block diagram showing the present invention;

Figure 4 is a schematic block diagram showing a first embodiment of the present invention;

Figure 5 is a schematic block diagram showing a second embodiment of the present invention; and

Figure 6 shows a microfluid ejection device according to the present invention.

Symbol Description

Traditional part (Figure 1)

1～fluid ejection device; 10～silicon substrate; 12～structural layer; 14～fluid cavity; 20～first heater; 22～second heater; 26～fluid.

Part of the present invention (Fig. 3-5)

1～fluid injection device; 2～microfluid heater (resistance); 3～resistance measuring device; 4～signal control unit; 5～heater with abnormal resistance value; 6～heater with normal resistance value; 7～after adjustment Driving conditions; 8~original standard driving conditions; 600~microfluid injection device; 610, 610a, 610b~heater; 620~heater detection device; 630~comparator; 640~signal control device.

Detailed ways:

For thermally driven microfluidic ejection devices, the resistance of the heater has a great influence on the ejection of microdroplets. According to a preferred embodiment of the present invention, the tested microfluid ejection device has 100-200 sets of heaters. The micro-fluid ejection devices of groups S1-S5 are micro-fluid ejection devices with a heater resistance value in a normal range, and the resistance value range is approximately 60-65 ohms (Ohm). When the driving voltage is 12 volts (V), the current value passing through each heater is about 160-170 milliamps (mA), and the resistance value of the wire of the circuit is about 10 ohms (Ohm). Under these conditions, with a heating time of 1.2 microseconds (μs) and an appropriate design of the nozzle hole size (diameter of about 16-18 microns (μm)), the volume of the ejected microfluidic droplets ranges from about 5 to 6 ( pico-liters, pl). At this time, it is assumed that the density of the fluid is equivalent to that of water, and the surface tension of the fluid is 26-30 dyne/cm (dyne/cm), and the viscosity coefficient is 1-2 decipoise (cp).

In contrast, the micro-fluid ejection devices of groups S6-S12 are micro-fluid ejection devices whose resistance value of the heater is higher than the normal range. (Ohm) or more accounts for about 5% to 22% of the overall proportion. The detected resistance value is 100-160% of the original standard resistance value. According to one embodiment of the present invention, the first to twelfth groups of microfluid ejection devices are subjected to the same driving conditions: when the driving voltage is 12 volts (V), the current value through each heater is about 160 to 170 milliamperes (mA) , the wire resistance of the circuit is about 10 ohms (Ohm), and the heating time is 1.2 microseconds (μs). The volume test of the micro-droplets ejected by the micro-fluid ejection device is carried out. The test results are shown in Table 1 in detail, wherein if the volume of micro-droplets sprayed by each nozzle hole in the microfluid ejection device reaches 5-6 (pico-liters, p1) accounting for 95% of the overall proportion, it is represented by ○, accounting for 90% of the overall proportion ～94% is represented by △, 85%～89% is represented by ☆, and 80%～84% is represented by ☆☆.

Table 1 result Heating time/microsecond (μs) droplet volume S1 normal range 1.2 ○ S2 normal range 1.2 ○ S3 normal range 1.2 ○ S4 normal range 1.2 ○ S5 normal range 1.2 ○ S6 above normal range 1.2 △ S7 above normal range 1.2 △ S8 above normal range 1.2 ☆ S9 above normal range 1.2 ☆☆ S10 above normal range 1.2 ☆☆ S11 above normal range 1.2 ☆☆ S12 above normal range 1.2 ☆

From the results in Table 1, it can be verified that the difference in the resistance value of each heater in the micro-fluid ejection device affects the quality of micro-droplet ejection.

Table 2 changes the driving conditions for each microfluid ejection device. According to a preferred embodiment of the present invention, the driving condition is changed by extending the heating time. Sequentially prolonging the heating time by 0.2 microseconds (μs) is used as a variable to improve the ejection result. As the heating time is increased, the yield rate of the ejection result of each microfluid ejection device is also increased. This result confirms that extending the heating time does improve the inkjet quality. Although the method for improving the ejection quality of the microfluid ejection device disclosed in the present invention is to prolong the heating time, it should be understood that this method is not limited to the present invention, and other methods, such as increasing the driving voltage or increasing the driving current, can also be used. The object of the present invention can be achieved. For example, when the driving voltage is increased to 100-120% of the original standard driving voltage, the injection efficiency can also be improved.

Table 2 Heating time/microsecond (μs) S6 S7 S8 S9 S10 S11 S12 1.2 △ △ ☆ ☆☆ ☆☆ ☆☆ ☆ 1.4 ○ △ ○ △ △ △ △ 1.6 ○ ○ ○ ○ ○ △ △ 1.8 ○ ○ ○ ○ ○ ○ ○

Although the inkjet quality of the microfluid ejection device can be improved by extending the heating time, a relatively derived problem is how to define a reasonable range for extending the heating time. Because too long heating time not only affects the operating frequency of the microfluid ejection device, but also may affect the original normal heating body. Excessive heating time will cause the normal heater temperature to be too high, resulting in a shortened heater life. And it may also cause excessive fluid injection to the injection quality. Table 3 is the test results of the fluid injection volume under different heating times for the microfluid ejection device with normal original resistance value. The results in Table 3 show that when the heating time is 2 microseconds (μs), there are indeed abnormal ejection conditions in the microfluid ejection device that originally ejected normally.

table 3 Heating time/microsecond (μs) S1 S2 S3 S4 S5 1.2 ○ ○ ○ ○ ○

1.4 ○ ○ ○ ○ ○ 1.6 ○ ○ ○ ○ ○ 1.8 ○ ○ ○ ○ ○ 2.0 ○ ○ ○ ○ △

Fig. 3 is a schematic block diagram showing the present invention. When performing fluid ejection, each microfluid emitter (for example, resistor) 2 located in the microfluid ejection device 1 will first measure the resistance value of each heater resistance through the resistance value measuring device 3, and each heating If the distribution range of the resistance value of the device meets the preset specification range, the previously set standard driving conditions will be activated. If not, the signal control unit 4 adjusts the driving signal of the fluid injection, and finally sends the corrected signal to the fluid injection device to obtain a preferred injection result.

first embodiment

Fig. 4 is a schematic block diagram showing a first embodiment of the present invention. According to the aforementioned test results, before fluid injection, a preferred embodiment of the present invention is to first measure the distribution range of the resistance value of each heater in the microfluid injection device, and if it meets the preset specification range, start Originally set standard driving conditions. If not, adjusting driving conditions for all heaters of the microfluid ejection device to improve ejection quality. Please refer to FIG. 4 , the heater 5 with abnormal resistance value and the heater 6 with normal resistance value are obtained by measuring the distribution range of the resistance value of each heater in the microfluid ejection device. The driving condition 7 is adjusted for all the heaters of the micro-fluid ejection device, and the ejection action is performed to improve the ejection quality of the micro-fluid ejection device.

second embodiment

Fig. 5 is a schematic block diagram showing a second embodiment of the present invention. In this embodiment, if the driving conditions are adjusted for all the heaters of the microfluid ejection device to improve the ejection quality according to the aforementioned test results. Although the preferred injection efficiency can be maintained, in the case of prolonging the heating time, abnormal injection conditions will occur in the heaters that originally sprayed normally. Therefore, before fluid injection, another preferred embodiment of the present invention is to first measure the resistance value of each heater in the microfluid injection device, and only adjust the driving conditions for heaters that exceed the standard, so as to improve the injection quality. Please refer to FIG. 4 , the heater 5 with abnormal resistance value and the heater 6 with normal resistance value are obtained by measuring the distribution range of the resistance value of each heater in the microfluid ejection device. Then, only the heaters in the microfluid ejection device that exceed the specifications are adjusted to the driving conditions 7, while the heaters that meet the standard specifications are still ejected under the originally set standard driving conditions 8, so as to improve the performance of the microfluid ejection devices. Jet quality. Although this embodiment has slightly more steps than the previous embodiment, it can improve the ejection quality and maintain the service life of the microfluid ejection device.

Figure 6 shows a microfluid ejection device according to the present invention. The microfluid ejection device 600 is composed of at least one heater 610 capable of heating fluid, a heater detection device 620 , a comparator 630 and a signal control device 640 . The heater detecting device 620 is electrically connected to the heater 610 and detects the resistance value of the heater through a current signal. The sensed signal is then compared to the comparator 630 with the standard operating resistance value. When the detected resistance value is higher than the standard operating resistance value, the driving signal input to the heater is adjusted by the signal control device 640 . According to another preferred embodiment of the present invention, the signal control device 640 outputs an adjustment drive signal to the heater 610a whose resistance value is higher than the standard operating resistance value, and outputs an adjustment driving signal to the heater 610a whose resistance value is equal to the standard operating resistance value. The heater 610b maintains the driving signal of the original standard operation.

Although the micro-fluid ejection device disclosed in the present invention is used for data printing processing of text or images, it should be understood that this application is not limited to the present invention, and the method for improving the ejection quality of the micro-fluid ejection device of the present invention can also be used for other purposes. For example, in another embodiment, the microfluid injection device can be used as a fuel injection system, or a drug injection device for biomedical technology.

The advantage of the present invention is to provide a microfluid ejection device and a method for improving the ejection quality of the microfluid ejection device. When the resistance value of some heaters in the microfluid ejection device exceeds the standard operating range, the resistance value detection device and The signal control unit adjusts the driving conditions for all or some (defective) heaters of the microfluid ejection device, so as to improve the ejection quality of the microfluid ejection device.

Therefore, within a certain signal adjustment range, in addition to effectively improving the use efficiency of the original microfluid injection device, it will not have a negative impact on the original normal heater.

Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person in the industry can make changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be The claims shall prevail.

Claims (19)

1. A method for improving microfluid injection quality, comprising the following steps: providing a microfluid ejection device having at least one fluid-heatable heater; detecting the resistance value of the heater; comparing the detection result of the resistance value of the heater with a standard operating resistance value; and When the detected resistance value is higher than the standard operating resistance value, the driving signal input to the heater is adjusted. 2 . The method for improving the ejection quality of microfluids according to claim 1 , wherein the range of the standard operating resistance is approximately 60-65 ohms (Ohm). 3. The method for improving the ejection quality of micro-fluid according to claim 1, wherein the step of adjusting the output driving signal is performed when the detected resistance value is 100-160% of the standard operating resistance value. 4. The method for improving the ejection quality of microfluid according to claim 1, wherein the step of adjusting the output driving signal is adjusting the driving time or the driving voltage. 5. The method for improving the ejection quality of microfluid according to claim 4, characterized in that the adjusted driving time is 100-150% of the standard operating driving time. 6. The method for improving the ejection quality of microfluids according to claim 5, characterized in that the standard operation driving time is 1.2 microseconds (μs). 7. The method for improving the ejection quality of microfluid according to claim 6, characterized in that the adjusted driving voltage is 100-120% of the standard driving voltage. 8. The method for improving the ejection quality of microfluid according to claim 7, wherein the standard operating driving voltage is 12 volts (V). 9. A method for improving the quality of microfluid injection, comprising the following steps: providing a microfluid ejection device having a plurality of heaters for fluid heating; detecting the resistance value of each of the heaters; comparing the detection result of the resistance value of each of said heaters with a standard operating resistance value; and For the heater whose resistance value is higher than the standard operation resistance value, output the adjustment drive signal, and for the heater whose resistance value is equal to the standard operation resistance value, maintain the original standard operation drive signal. 10 . The method for improving the ejection quality of microfluid according to claim 9 , wherein the range of the standard operating resistance is approximately 60-65 ohms (Ohm). 11 . 11. The method for improving the ejection quality of microfluids according to claim 9, wherein the step of adjusting the output drive signal is performed when the detected resistance value is 100-160% of the standard operating resistance value. 12. The method for improving the ejection quality of microfluid according to claim 9, wherein the step of adjusting the output driving signal is adjusting the driving time or the driving voltage. 13. The method for improving microfluid ejection quality according to claim 12, characterized in that the adjusted driving time is 100-150% of the standard operating driving time. 14. The method for improving the ejection quality of microfluid according to claim 13, wherein the standard operation driving time is 1.2 microseconds (μs). 15. The method for improving the ejection quality of microfluid according to claim 14, characterized in that the driving voltage is adjusted to be 100-120% of the standard driving voltage. 16. The method for improving microfluid ejection quality according to claim 15, wherein the standard operating driving voltage is 12 volts (V). 17. A microfluid ejection device comprising: at least one heater capable of heating the fluid; A heater detection device, electrically connected to the heater to detect the resistance value of the heater; a comparator to compare the detection result of the resistance value of the heater with a standard operating resistance value; and A signal control device, when the resistance value of the heater is higher than the standard operating resistance value, provides an adjusted driving signal to the heater. 18. The micro-fluid ejection device according to claim 17, wherein the heater detection device detects the resistance value of the heater through a current signal. 19. The microfluid ejection device according to claim 17, characterized in that it comprises a plurality of said heaters, and said signal control component performs a function on said heaters whose resistance value is higher than said standard operating resistance value Outputting an adjustment drive signal, and maintaining the original standard operation drive signal for the heater whose resistance value is equal to the standard operation resistance value.

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