JPH0726269U - Water droplet removal control device - Google Patents

Abstract

(57) [Summary] [Purpose] Ultrasonically removes water droplets attached to a large mirror effectively and without changing the design. [Structure] Set the power supplied to the oscillator to a frequency band greater than 5 [kHz] and 15 [kHz] or less, and 15 [kHz]
/ sec] and set the sweep speed to 30 [kHz / sec] or less.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a water drop removal control device for removing water drops attached to a mirror of an automobile or the like.

[0002]

[Prior art]

 Hitherto, as a water drop removal control device for removing water drops attached to a mirror of an automobile or the like, a device using ultrasonic waves has been proposed. In this method, a piezoelectric oscillator or the like is driven to vibrate the mirror surface in the ultrasonic range to repel the attached water droplets. Usually, the driving of the vibrator is set under the condition that the mirror surface resonates from the viewpoint of efficiency, but it is safer to remove the water droplets in the shortest time possible. The resonance frequency of the mirror is not limited to a specific frequency, and there are multiple resonance frequencies. Therefore, the frequency bandwidth including these resonance frequencies is set, and the frequency of the oscillator is swept within the frequency bandwidth. ing. As an example of this, in Japanese Patent Laid-Open No. 3-57752, ± 30% of the resonance frequency is set as the set frequency bandwidth. Further, in Japanese Patent Laid-Open No. 4-38251, a frequency bandwidth of 35 to 65 kHz is set, and this is swept in 0.5 to 1.5 seconds.

[0003]

[Problems to be solved by the device]

 However, in the above example, the target is a small mirror used in passenger cars and the like, and it is difficult to apply it to large mirrors used in trucks, one-box cars, etc. for the following reasons. That is, the resonance frequency depends on the mass of the vibrating body (here, the mirror), and decreases as the mass increases. Therefore, with the above setting value, a sufficient resonance state cannot be obtained, and it is difficult to properly remove water droplets. Also, in order to vibrate a large mirror with a large mass, it is necessary to supply a large amount of energy to the vibrator, which is used in recent years due to the demand for multifunctionality and the demand for smaller size and lighter weight in door mirrors. Since it is difficult to increase the allowable amount of the harness, there is a problem that the energy supplied to the vibrator cannot be increased. Then, this invention aims at providing the water droplet removal apparatus which solved the said problem.

[0004]

[Means for Solving the Problems]

 In order to solve the above-mentioned object, the present invention provides a water drop removing device in which a piezoelectric vibrator is swept in a certain frequency band to excite ultrasonic vibrations in a mirror to remove water drops adhering to the mirror surface. The oscillator is swept at a predetermined sweep speed fsv, and the sweep frequency band width fw is set within a range of 5 [kHz] <fw ≤ 15 [kHz]. Further, the sweep speed fsv is set in a range of 15 [kHz / sec] <fsv≤30 [kHz / sec].

[0005]

[Action]

 When the piezoelectric vibrator is driven, the mirror vibrates in the ultrasonic range. Due to this vibration, water droplets adhering to the mirror surface are repelled. Therefore, it is necessary to vibrate the mirror efficiently. For this purpose, a method of increasing the power supplied to the vibrator, a method of driving the vibrator for a long time, a method of optimizing the mounting position of the vibrator, and the like can be considered. However, in order to increase the power supplied to the vibrator, there is the problem that the power allowance of each component such as the harness and transformer must be increased. Under the present circumstances, it is difficult to make the harness thick due to the demands for the door mirrors to have various functions and the demands for design and the like. In addition, it is not preferable for driving safety to prolong the driving time. Furthermore, if the oscillator mounting position is displaced from the center of gravity of the mirror, the resonance frequency will increase, and as a result, the average power that can be input to the oscillator can be increased, making it possible to remove water droplets. However, in this case, the weight balance of the mirrors becomes unbalanced, which may cause the chattering of the mirrors at high speed. Therefore, the present invention secures the visibility or safety without increasing the time for vibrating the mirror by the vibrator, and makes the resonance time longer than before to improve the water drop removal characteristics. Therefore, the power that can be input to the vibrator is increased by setting the frequency band width and sweep speed as frequency band width: 5 to 15 kHz and sweep speed: 15 to 30 kHz / sec. This principle will be described in detail with reference to FIG. Fig. 5 (a) shows a case where vibration is performed under the conditions of frequency band width: 30 kHz, sweep speed; 60 kHz / sec (an example of conventional technology), and Fig. 5 (b) shows frequency band width; 15 kHz, sweep speed; The figure shows the case of vibrating under the condition of 30 kHz / sec (one example of the present invention). In the figure, the dotted line shows the corresponding points of the frequency, and the alternate long and short dash line shows the average value of the input power. As can be seen from the figure, the frequency band applied to the vibrator is narrowed, and the frequency band is set to reciprocate once per second as in the conventional case. At this time, the frequency bandwidth should include the frequency at which the mirror resonates. With this setting, Fig. 5 (a) becomes Fig. 5 (b), and the average value of the input power increases. This means that the mirror will resonate longer. Therefore, even with a large mirror, it is possible to sufficiently remove water droplets without having to thicken the harness or the like.

[0006]

【Example】

 An embodiment of the present invention will be described with reference to the drawings. Figure 1 shows a cross section of a large door mirror with a mirror area of about 200 cm2 used in one-box vehicles and trucks equipped with a water drop removing device. The door mirror 10 has a dish-shaped support member 13 on the back surface of the mirror 11 (on the right side in FIG. 1; the same applies hereinafter), and a vibrator 14 for generating ultrasonic waves is provided on the back surface of the support member 13, and the support member is also provided. A heater 12 is provided on the surface of 13 via a spacer 15. Water droplets attached to the surface of the mirror 11 are removed by the heater 12 and the vibrator 14. FIG. 2 is a block diagram of a drive circuit used to drive the vibrator 14, in which the noise of the power source is removed by the noise filter 21 and supplied. Then, the triangular wave generating circuit 22 generates a triangular wave signal (basic waveform), and the basic waveform is input to the voltage controlled oscillation (VCO) circuit 23. In this voltage controlled oscillator circuit 23, the drive frequency is generated (modulated) by the peak value of the basic waveform. On the other hand, the timer circuit 24 outputs a signal to the gate circuit 25 for a predetermined time in order to manage the time of generating ultrasonic waves, and controls the time when the output from the voltage controlled oscillator circuit 23 is input to the drive circuit 26. The drive circuit 26 drives the vibrator 14 based on the input signal. FIG. 3 shows a basic waveform. As can be seen from the figure, the basic waveform is set so as to sweep the frequency band width (35 to 50 kHz in Fig. 3) including multiple resonance frequencies of the mirror at a predetermined sweep speed (30 kHz / sec in Fig. 3). It is configured to make one round trip per second. Fig. 4 shows the case where a large mirror oscillator used in a truck is vibrated under conventional conditions (Fig. 4 (a)) and under the above conditions (Fig. 4 (b)). Yes, and Table 1 summarizes these driving conditions, the input power (average value) of the vibrator, and the water droplet removal results. The dotted line in FIG. 4A shows the case where the harness resistance when supplying electric power from the drive circuit 26 to the vibrator 14 is sufficiently small.

[Table 1] From this result, it is possible to increase the power input to the oscillator and remove water droplets better by setting the frequency band width and sweep speed to the above values in the case of a large mirror. . According to various experiments conducted by the present inventor, the oscillator driving condition used for the large mirror is preferably such that the frequency band width fw is in the range of 5 [kHz] <fw ≤ 15 [kHz], and the sweep speed fsv is The range of 15 [kHz / sec] <fsv ≦ 30 [kHz / sec] was suitable.

[0007]

[Effect of device]

 As described above, in the large mirror, input to the oscillator by setting the frequency band width to 5 to 15 kHz and the sweep speed 15 to 30 kHz / sec without making the harness thick and increasing the capacity of the transformer etc. We were able to increase the average power value. This has made it possible to obtain good water drop removal characteristics without increasing the operating time of the vibrator. In addition, since the sweep speed is slowed, the amount of water droplets naturally falling or moving increases, and it becomes possible to improve the water droplet removal property by 10 to 20% compared to the conventional case.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a mirror applied to the present invention.

FIG. 2 is a block diagram for vibrating a vibrator.

FIG. 3 is a diagram showing basic waveforms generated by the block diagram of FIG.

FIG. 4 is a diagram showing a waveform of a vibrator input power, wherein (a) is a conventional drive condition and (b) is a drive condition according to the present invention.

[Explanation of symbols]

 11 Mirror 14 Oscillator 22 Triangular Wave Generation Circuit 23 Voltage Controlled Oscillation Circuit 24 Timer Circuit 25 Gate Circuit 26 Drive Circuit

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[Procedure amendment]

[Submission date] December 24, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a mirror applied to the present invention.

FIG. 2 is a block diagram for vibrating a vibrator.

FIG. 3 is a diagram showing basic waveforms generated by the block diagram of FIG.

FIG. 4 is a diagram showing a waveform of vibrator input power, in which (a) is a conventional drive condition and (b) is a drive condition according to the present invention.

FIG. 5 is a diagram showing a basic waveform applied to a conventional technique. (A) shows a frequency band width of 30 kHz, and (b) shows a frequency band width when the vibration speed is 60 kHz / sec. 15kHz, sweep speed 30kHz / s
It is a figure which shows the case where it vibrates on condition of ec.

[Explanation of Codes] 11 Mirror 14 Oscillator 22 Triangular Wave Generation Circuit 23 Voltage Controlled Oscillation Circuit 24 Timer Circuit 25 Gate Circuit 26 Drive Circuit

Claims (2)

[Scope of utility model registration request] 1. A water drop removing device, wherein a piezoelectric vibrator is swept oscillated in a certain frequency band to excite ultrasonic vibrations on a mirror to remove water drops adhering to the mirror surface. Sweep at the sweep speed fsv,
Further, the sweep frequency band width fw is set in a range of 5 [kHz] <fw ≤ 15 [kHz], wherein the water drop removing device is characterized. 2. The water droplet removing device according to claim 1, wherein the sweep speed fsv is set in a range of 15 [kHz / sec] <fsv ≦ 30 [kHz / sec].