JPS6311936B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic atomizer, and an object thereof is to provide an ultrasonic atomizer that can reliably start atomization and has low average power consumption. .

Conventionally, as shown in FIG. 1, this type of ultrasonic atomizer uses a capillary tube to direct liquid 4 in a water storage tank 3 to the lower end of a spraying surface 1a, which is a substantially vertical surface, of an ultrasonic horn 1 driven by an electrostrictive element 2. The electrostrictive element 2 that vibrates the ultrasonic horn 1 by bringing the upper end of the water absorbing body 5 into contact with the phenomenon is driven by the output of the drive oscillation circuit 6, and by using the water absorbing body 5, water is always stored. A fixed amount of the liquid 4 in the tank 3 is supplied to the spray surface 1a of the ultrasonic horn 1, thereby stabilizing the spray and minimizing the power required for the spray. In this case, the spray of the liquid 4 is stable if the amount of liquid supplied to the spray surface 1a is smaller than the amount that can be sprayed due to the vibration of the ultrasonic horn 1 (an amount proportional to the vibration amplitude of the ultrasonic horn 1). By the way, in such an ultrasonic atomizer, for example, a DC- voltage booster is used to boost the power supply voltage of the power source 8 such as a battery.
When the DC converter 7 output is applied to the drive oscillation circuit 6, when the power is turned on, the drive oscillation circuit 6
The output voltage of DC-DC converter 7 applied to
Since V _DC rises slowly as shown in Figure 2,
The spray surface 1 of the ultrasonic horn 1 for a certain period of time after the power is turned on.
There has been a problem in that the amount of liquid supplied to a becomes larger than the amount that can be sprayed at the time of startup, and spraying does not start. In other words, if the rise of the output of the DC-DC converter 7 is slow, the rise of the output of the drive oscillation circuit 6 will naturally be delayed, and the vibration amplitude of the ultrasonic horn 1 will reach a steady state with a certain time delay after the power is turned on. . In this case, the liquid 4 is supplied to the spray surface 1a even though no spraying is performed while the sprayable amount is smaller than the liquid supply amount, so the spray surface 1a is A water film 4a is formed on the ultrasonic horn 1a, and the resonant frequency of the ultrasonic horn 1 is shifted, and the impedance seen from the drive power source, that is, the drive oscillation circuit 6, increases and the drive current decreases, causing the output of the DC-DC converter 7 to decrease. Even when the steady state is reached, the vibration amplitude of the ultrasonic horn 1 becomes smaller than the predetermined value, and as shown in FIG.
As shown in FIG. 2, there was a problem in that the water film 4a formed on the spray surface 1a became thick and turned into water droplets, but the spraying did not start. In order to solve this problem, the output voltage V _DC of the DC-DC converter 7 should be set high so that spraying can be performed reliably even when a water film 4a is formed on the spray surface 1a. , in the steady spray state after the water film 4a has been atomized, as shown in FIG.
There was a problem in that the output of the converter 7 became larger than necessary, resulting in higher average power consumption and faster battery consumption. The present invention has been made in view of the above points.

Examples will be described below using figures. FIG. 4 shows a specific circuit of an embodiment of the present invention.
6 is a drive oscillation circuit that drives the electrostrictive element 2;
Oscillation transistor Q ₁ , oscillation transformer TR, chiyoke coil L ₁ , capacitors C ₁ , C ₂ , resistors R ₁ , R ₂
It is formed in 9 is the output voltage of the DC-DC converter 7 after the power switch SW ₁ is turned on.
When V _DC exceeds the preset voltage
Oscillation circuit 6 that drives the DC-DC converter 7 output V _DC
This is a switch _circuit that applies an electric current to
and resistors R ₃ and R ₄ . Figure 5 shows a DC-DC converter 7 with a starting circuit 10 added.
This shows a specific circuit example, and the DC-DC converter 7 includes transistors Q ₃ to _{Q 6} , diodes D ₁ ,
The starting circuit 10 is formed by a Zener diode ZD ₂ , capacitors C ₃ and C ₄ and resistors R ₅ to R ₁₁ .
is transistor Q ₇ , diode D ₂ , and capacitor
It is formed by C ₅ and resistors R ₁₂ and R ₁₃ .

Now, in the DC-DC converter 7, the voltage V _R10 across the resistor R ₁₀ is equal to the base-emitter voltage V _BE of the transistor Q ₄ and the Zener voltage of the Zener diode ZD _2.
When _{the sum of the V} It is now possible to obtain current characteristics. In this embodiment, since the transistor _Q7 of the starting circuit 10 is connected between the base and emitter of the transistor _Q4 , when the power switch _SW1 is turned on, the capacitor _C5 is charged from the battery 8. Transistor Q ₇ is turned on by the current and the base and emitter of transistor Q ₄ are short-circuited, so even if current flows through Zener diode ZD ₂ (V _R10 > V _BE + V _ZD2 ), transistor Q ₄ remains off, no feedback is applied, and constant current characteristics cannot be obtained, i.e.
As shown in FIG. 6, the output voltage V _DC of the DC-DC converter 7 gradually increases at the same time as the power switch SW ₁ is turned on, and once becomes larger than the normal output voltage V _DCO . After that, as the charging of capacitor C ₅ progresses, transistor Q ₇ shifts to the off state, and when charging of capacitor C ₅ is completed, transistor Q ₅ is completely turned off, and the DC-DC converter 7 returns to its original operation, reducing the output voltage. V _DC becomes the normal output voltage V _DCO . Therefore, only for a certain period of time T after the power is turned on.
The output voltage V _DC of the DC-DC converter 7 is designed to be higher than the normal output voltage V _DCO . By the way, in the embodiment, the switch circuit 9
The operating threshold level V _ON at which the DC-DC converter 7 turns on is set to be higher than the steady output voltage V _DCO of the DC-DC converter 7, and after the power is turned on, the output voltage V _DC of the DC-DC converter 7 reaches the above operating threshold. When the level V _ON or higher is reached, the SCR S of the switch circuit 9 is turned on, the transistor Q ₂ is turned on, and the output voltage V _DC of the DC-DC converter 7 is applied to the drive oscillation circuit 6. FIG. 7 shows the voltage V _C1 across the capacitor _C1 . Therefore, a voltage with a steep rise and a large voltage value immediately after application is applied to the drive oscillation circuit 6, and the ultrasonic horn 1 is driven with a large vibration amplitude immediately after starting, and the ultrasonic horn 1 is driven with a large vibration amplitude immediately after starting. Since the vibration amplitude of the horn 1 is small, there is almost no period during which the amount of liquid supplied is larger than the amount that can be sprayed, and a water film 4a appears on the spraying surface 1a of the ultrasonic horn 1 as in the conventional example. This eliminates the inconvenience of not being able to start spraying.
In addition, in the embodiment, by providing a starting circuit 10, the output voltage V _DC of the DC-DC converter 7 is increased for a certain period T after the power is turned on, and the driving energy of the ultrasonic horn 1 is increased to perform spraying. Although this is done to ensure a more reliable start, it goes without saying that a normal DC-DC converter 7 having the output characteristics as shown in FIG. 2 may also be _used . is set slightly lower than the steady state output voltage V _DCO .

As described above, the present invention brings into contact the upper end of the water absorbing body that sucks up the liquid in the water storage tank by capillary action to the lower end of the spray surface which is a substantially vertical plane of the ultrasonic horn driven by the electrostrictive element, and In an ultrasonic atomizer configured to supply battery power via a DC-DC converter to a drive oscillation circuit that drives a strain element, the output voltage of the DC-DC converter exceeds a preset voltage after the power is turned on. Sometimes DC-DC
Since it is equipped with a switch circuit that applies the output voltage of the converter to the drive oscillation circuit, a voltage with a steep rise is applied to the drive oscillation circuit, making it possible to spray by increasing the vibration amplitude immediately after starting the ultrasonic horn. Since the amount can be increased, it has the advantage of being able to start spraying reliably, and unlike conventional methods, it is not necessary to increase the output voltage of the DC-DC converter to ensure that spraying starts. Therefore, the average power consumption is reduced, which is particularly useful when using a power source with limited capacity such as a battery.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of the conventional example, FIGS. 2 and 3 a to 3e are explanatory diagrams of the same operation, FIG. 4 is a circuit diagram of an embodiment of the present invention, and FIG. 5 is a detailed diagram of the main parts of the same. The circuit diagram and FIGS. 6 and 7 are explanatory diagrams of the same operation. 1 is an ultrasonic horn, 1a is a spray surface, 2 is an electrostrictive element, 3 is a water storage tank, 4 is a liquid, 5 is a water absorber, 6
1 is a drive oscillation circuit, 7 is a DC-DC converter, 8 is a battery, and 9 is a switch circuit.

Claims (1)

[Claims] 1 A drive that drives the electrostrictive element by bringing the upper end of a water absorbing body that sucks up liquid in a water storage tank by capillary action into contact with the lower end of the spray surface, which is a substantially vertical surface of an ultrasonic horn driven by an electrostrictive element. DC− to the oscillation circuit
In an ultrasonic atomizer configured to supply battery power via a DC converter, after turning on the power
An ultrasonic atomizer comprising a switch circuit that applies the output voltage of the DC-DC converter to a drive oscillation circuit when the output voltage of the DC-DC converter exceeds a preset voltage.