JPH03253449A - Water droplet removing device of mirror for car - Google Patents

Abstract

PURPOSE:To remove water droplets on a panel by providing an oscillating means, a frequency-domain setting means and a cycle setting means for setting two kinds of cycles of a cycle necessary for change in a frequency band of the oscillating means and a suspended cycle for suspending driving of the oscillating means between a former cycle and a latter cycle. CONSTITUTION:An oscillating means comprising a voltage control oscillating circuit 17 for oscillating a supersonic oscillator 2 within a frequency band including a designated plurality of resonance frequencies and an oscillator driving circuit 18 for driving the piezoelectric oscillator 2 is provided. A frequency- domain setting means comprising a routine for gradually raising an input frequency of this oscillating means from a lower limit frequency to an upper limit frequency is provided. Moreover, a cycle necessary for change in the frequency band of the oscillating means is fixed and a suspended period for suspending driving of the oscillating means is set between a former cycle and a latter cycle. Thus, configuration change of water droplets can not catch up with change rate of an oscillation frequency and drop effect of the water droplets is promoted.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a device for removing water droplets from automobile mirrors, which maintains visibility on mirror surfaces such as fender mirrors and door mirrors, and in particular, removes water droplets that have adhered to mirror surfaces. This invention relates to the structure of a water droplet removal device for automobile mirrors that removes water droplets, ice, frost, fog, etc.

[Prior Art] As a conventional example of this type of water droplet removing device for an automobile mirror, there is a technique described in Japanese Patent Application Laid-Open No. 62-238149 and the like.

That is, in a water droplet removal device in which a vibrator is attached to a panel and the inertial force of the water droplets adhering to the panel surface is made larger than the surface tension of the water droplet by the vibration manual force of the vibrator to remove the water droplets, the input by the vibrator is It is equipped with a control device that changes the vibration frequency.

Therefore, the panel can be caused to resonate regardless of the degree of adhesion or scattering of water droplets to the panel, and the water droplet removal performance can be improved.

However, in the conventional device described above, only a single resonance mode is used to cause the panel to resonate, so the vibration mode of the panel is single. As a result, the positions of the antinode and node of the vibration generated on the panel are constant, and a problem arises in that minute water droplets adhering to the node position cannot be removed.

In order to solve these problems, for example,
No. 3-69646, etc., proposes a control device that converts the frequency of input vibration from a vibrator at a constant cycle and changes the positions of the antinode and node of the vibration generated on the panel.

[Problems to be Solved by the Invention] However, even if the frequency of the input vibration from the vibrator is converted at a constant cycle, water droplets on the panel cannot be removed cleanly. This is because vibrations that cause attached water droplets to move back and forth occur in a portion of the panel.

Water droplets attached to such locations cannot be easily removed from the panel surface even if they are dancing on the panel surface because the energy transmitted from the panel surface is consumed by the water droplet's reciprocating movement.

Therefore, in order to eliminate the above-mentioned disadvantages, the present invention provides a technology to vibrate the mirror in multiple vibration modes, provide a stop section in between, and cleanly remove the water droplets on the panel by allowing the water droplets to drip off. This is a major issue.

[Means for Solving the Problems] The water droplet removal device for an automobile mirror according to the invention of claim 1 is provided as a means for vibrating an oscillating means for vibrating an ultrasonic vibrator bonded to the back surface of the mirror at a set frequency. ,
frequency domain setting means for setting a variable frequency bandwidth including a plurality of resonant frequencies within the frequency range setting means; The apparatus includes cycle setting means for setting two types of cycles, including a pause cycle for stopping the drive.

In a water droplet removing device for an automobile mirror according to a second aspect of the present invention, the frequency range setting means and the period setting means are constituted by a microcomputer and a D/A converter.

[Function] In the invention of claim 1, the period setting means sets the period required for changing the frequency band of the specified oscillation means and the rest period for stopping the vibration of the oscillation means, and based on these,
The variable frequency bandwidth input to the vibration means for vibrating the ultrasonic transducer is set by the frequency domain setting means, and the mirror is then vibrated by the vibration means so as to pass through a plurality of resonant frequencies and change the frequency. .

Therefore, it is possible to shorten the time during which the frequency that moves within the variable frequency bandwidth of the vibration means that vibrates the ultrasonic transducer bonded to the back surface of the mirror stays at multiple resonance frequencies, thereby reducing power consumption. be able to. For example, even if the ultrasonic vibrator cannot atomize the water droplets on the mirror surface and they are dancing on the mirror surface, the shape of the water droplets that continue to vibrate on the mirror surface will change depending on the rate of change of the vibration frequency of the mirror surface. However, even if the ultrasonic vibrator is used to atomize using the lateral effect of the mirror surface,
At the leading edge and trailing edge of the frequency change and rest period, the longitudinal effect of apparently different characteristics can be further added to promote the water droplet drop effect. By setting a period in which the vibration suddenly stops at the front and rear edges of the rest period, even water droplets dancing on the mirror surface can be
The shape change due to the inertia of the water droplets due to the sudden stop of the vibration frequency on the mirror surface cannot be accommodated, and the dripping of the water droplets can be promoted.

In the invention of claim 2, since the frequency range setting means and the period setting means are constituted by a microcomputer and a D/A converter, the variable frequency bandwidth of the output frequency for vibrating the ultrasonic transducer and the oscillation Since the cycle required for changing the frequency band of the means can be set arbitrarily, settings that take into consideration the state of adhesion to the surface of the mirror can be made using the same hardware.

[Example code] Examples of the present invention will now be described.

FIG. 1 is an overall configuration diagram of a control circuit for controlling a water droplet removal device for an automobile mirror according to an embodiment of the present invention, and FIG. It is an explanatory diagram of waves.

First, the principle of bending the mirror 1 using the transverse effect of this embodiment will be explained in detail with reference to FIG.

First, when the (+) terminal of the DC power source E is connected to the lead wire 3 and the (-) terminal of the DC power source E is connected to the lead wire 4, a strong contraction force acts on the ultrasonic vibrator 2 in the radial direction due to the transverse effect. As a result, the mirror 1 is bent downward as shown in FIG. 2(a). Also,
When connecting the (-) terminal of the DC power source E to the lead wire 3 and the (+) terminal of the DC power source E to the lead wire 4, the ultrasonic transducer 2
A strong stretching force acts in the radial direction due to the transverse effect, causing the mirror 1 to bend upward as shown in FIG. 2(b).

Then, when the output of the alternating current power supply AC is supplied to the ultrasonic transducer 2, the mirror 1 is repeatedly bent. Here, if the frequency of the AC power is selected to be around an integral multiple of the lowest resonant frequency of the mirror 1, the mirror 1 will resonate, and a standing wave that is uniform and large in amplitude will be generated throughout the mirror 1. This standing wave causes the mirror surface to vibrate at high speed. At this time, the water droplets attached to the mirror surface are given high kinetic energy by the mirror 1, and are dropped or atomized by gravity and removed from the surface of the mirror 1, thereby removing the water droplets etc. from the mirror surface. Become.

In this way, the ultrasonic transducer 2 has a longitudinal effect in which it expands and contracts in the same direction as the direction of the applied electric field, and a lateral effect in which it expands and contracts in a direction perpendicular to the direction of the applied electric field. Generally, the resonant frequency due to the transverse effect is lower than the resonant frequency due to the longitudinal effect. In this embodiment, a bending wave is generated in the mirror 1 using a transverse effect. However, in some cases, such as mirrors with high resonance frequencies, it may be preferable to utilize the longitudinal effect. In other words, when implementing the present invention, the present invention is not limited to generating bending waves in the mirror 1 using a transverse effect, but also includes a method in which the mirror 1 is expanded and contracted using a longitudinal effect. be able to.

Next, electrical control of the water droplet removing device for an automobile mirror according to the present embodiment shown in FIG. 1 will be explained.

In the figure, a start switch 11 is a switch disposed at a position that can be easily operated by a driver inside the vehicle who drives the water droplet removal device for an automobile mirror according to this embodiment. The start switch 11 is inputted to the microcomputer 13 via an input circuit 12, and when turned on, the signal is "L".
is input to the input circuit 12, and "H" is input when it is off.

The microcomputer 13 is an in-vehicle battery 14
Power is supplied from a power supply circuit 15 such as a constant voltage circuit that is supplied with power from a constant voltage circuit.

The output of the microcomputer 13 is passed through a D/A converter 16 that converts digital input into analog output, and is then connected to a voltage controlled oscillation circuit (which controls the output frequency at the input terminal).
The signal is supplied to an oscillation means consisting of a V-F conversion circuit (V-F conversion circuit) 17 and a vibrator drive circuit 18 that drives the piezoelectric vibrator 2.

That is, the frequency of the AC power that makes the plurality of resonant frequencies supplied to the ultrasonic transducer 2 within its frequency band is supplied from the transducer drive circuit 18 . The vibrator drive circuit 18 is supplied from the voltage controlled oscillation circuit 17, and the output frequency of the voltage controlled oscillation circuit 17 is determined by the output voltage of the D/A converter 16. It is controlled by 13 digital signals. The analog output voltage of the D/A converter 16 is always supplied to the voltage controlled oscillation circuit 17, and
The voltage controlled oscillation circuit 17 applies an output of a predetermined frequency to the vibrator drive circuit 18.

The output of the vibrator drive circuit 18 is controlled by a strobe signal 19 output from the microcomputer 13, and only when the strobe signal 19 is on, the vibrator drive circuit 1
8 supplies alternating current power of a predetermined frequency to the ultrasonic transducer 2.

The ROM of the microcomputer 13 stores a control program for controlling the water droplet removing device for an automobile mirror according to the present embodiment, and the program is controlled as follows.

FIG. 3 is a flowchart of a program for controlling a water droplet removing device for an automobile mirror according to an embodiment of the present invention. Further, FIG. 4 is a time chart showing the driving frequency and driving period of an ultrasonic transducer used in controlling the water droplet removing device for an automobile mirror according to an embodiment of the present invention.

First, at the same time as the power supply is connected, initialization is performed in step S1, and the strobe signal 19 is also set to OFF. In step S2, the state of the start switch 11 is determined, and when the start switch 11 is off, the strobe signal 19 remains off and stands by. When the start switch 11 is turned on, in step S3, a predetermined frequency bandwidth (40KHz to 60KHz in this embodiment) including a plurality of resonance frequencies is selected.
Hz) is repeatedly applied to the ultrasonic transducer 2, and in this embodiment, a timer built in the microcomputer is set to 5 seconds. In step S4, an initial value fo is set as the frequency f output to the ultrasonic transducer 2.

Specifically, a digital value representing the initial value fo is set in the microcomputer 13, and the D/A converter 1
6 input. Further, in step S5, a cycle T for changing the predetermined variable frequency bandwidth is set.

Then, in step S6, the microcomputer 13 generates a predetermined digital signal from the digital value corresponding to the frequency f, outputs it to the D/A converter 16, and inputs it to the voltage controlled oscillation circuit 17. Then, in step S7, the strobe signal is turned on, and the frequency f is applied to the ultrasonic transducer 2.
= input fo. Furthermore, in step S8, the frequency applied to the ultrasonic transducer 2 is set to f=f-11f and stepped up by a minute frequency. In step S9, it is determined whether the frequency of the variable frequency bandwidth of the predetermined period T has been output.

When the frequency of the variable frequency bandwidth of the predetermined period T is not output, the routine from step S6 to step S9 is repeatedly executed. That is, from step S6 to step S9
The routine sets the frequency of a given variable frequency bandwidth to
In this embodiment, the frequency is increased little by little in the range of 40 KHz to 60 KHz.

When it is determined in step S9 that the frequency of the variable frequency bandwidth of the predetermined period T has been output, the strobe signal is turned off in step S10, and the vibration between the previous period and the next period is stopped in step S11. pause period S(10
After waiting for the pause period S to elapse, it is determined in step S12 whether 5 seconds of one drive time have elapsed.
The routine from step S6 to step S12 is repeatedly executed.

That is, in this embodiment, as shown in FIG. 4(a), the period T for sequentially increasing the frequency applied to the ultrasonic transducer 2 may be 500 m5, and the pause period S may be 100 m5; As shown in FIG. 4(b), the period T for sequentially lowering the frequency applied to the ultrasonic transducer 2 may be 500 ws, and the pause period S may be 100 m5. Moreover, as shown in FIG. 4(C),
After sequentially increasing the frequency applied to the ultrasonic transducer 2,
It is also possible to set the lowering period T to 10100O and the rest period S to 100m5.

If it is determined in step S12 that 5 seconds of one driving time have elapsed, the process waits for the start switch 11 to be turned on again in step S2.

As described above, the water droplet removing device for an automobile mirror according to the embodiment of the present invention has an ultrasonic vibrator 2 bonded to the back surface of the mirror 1.
an oscillation means consisting of a voltage-controlled oscillation circuit 17 that vibrates within a frequency band including a plurality of specified resonance frequencies, and a vibrator drive circuit 18 that drives the piezoelectric vibrator 2; Upper limit frequency fo+J
a frequency range setting means consisting of a routine from step S4 to step S9 to gradually increase the frequency to f-n; and a period T required for changing the frequency band of the oscillation means is fixed;
The apparatus is provided with cycle setting means comprising a routine from step S6 to step 313 for setting a pause cycle S for stopping the driving of the oscillation means between the previous cycle and the next cycle.

Therefore, as shown in FIG. 4 (a) to (C),
The output frequency f of the oscillation means that drives the piezoelectric vibrator 2 is set to a frequency fo of a variable frequency bandwidth that includes a plurality of resonance frequencies.
The period T at which one or both of the frequencies fo and Jf-n is changed is fixed. Therefore, the time during which the device stays at a predetermined resonance frequency is shortened, and the integral value of the current flowing during resonance can be reduced accordingly, resulting in a reduction in power consumption. In addition, since the frequency changes rapidly at the front and rear edges of the pause period when applied to or stopped from the mirror 1, even if there are water droplets dancing on the surface of the mirror 1 without being able to atomize the water droplets, the water droplets will not be applied to the water droplets. The energy suddenly changes, and the changing speed of the vibration frequency cannot correspond to the change in the shape of the water droplets that continue to vibrate on the mirror surface. An apparent vertical effect is added to the mirror surface, which can promote the phenomenon of water droplets dripping along the mirror surface (hereinafter simply referred to as the "drop effect").
The water droplet removal efficiency can be improved.

In the above embodiment, the output frequency f of the oscillation means is
The frequency fo or fo+Jf-n of the variable frequency bandwidth is suddenly changed from the stopped state to the frequency fo or fo+Jf-n of the variable frequency bandwidth, and the frequency fo or fo-1-Jf-n of the variable frequency bandwidth is suddenly changed to the stopped state. The rapid change in the output frequency of the means imparted a sudden vertical effect to the horizontal effect that atomizes the mirror surface with the ultrasonic vibrator 2, and the vibration energy also changed rapidly. Since it imparts energy, the sudden change in the imparted energy breaks the balance with the vibrating water droplet particles, promoting the drop effect of the water droplets.
Water droplets, ice, frost, fog, etc. attached to the mirror surface can be removed with high efficiency.

In this way, the water droplet removal device for an automobile mirror according to the above embodiment uses the voltage-controlled oscillation circuit 17 and the vibrator drive as an oscillation means for vibrating the ultrasonic vibrator 2 bonded to the back surface of the mirror 1 at a specified frequency. However, when carrying out the present invention, any circuit that can obtain the frequency output specified by the ultrasonic transducer 2 by external input may be used, and the voltage controlled oscillation circuit 17 and the transducer drive It is not limited to the combination of circuits 18.

Further, the frequency range setting means for specifying the variable frequency bandwidth of the frequency for vibrating the oscillation means of the oscillation means including a plurality of resonance frequencies, sets the variable frequency bandwidth of the output frequency f of the oscillation means to the frequency f.

The frequency is gradually increased from the lower limit frequency to the upper limit frequency in a routine from step S4 to step S9 in which the frequency fo+Jf-n is specified from the lower limit frequency to the upper limit frequency. However, when implementing the present invention, the variable frequency bandwidth can be specified as long as it includes a plurality of resonant frequencies and can only change the bandwidth of a predetermined frequency. A frequency modulation circuit that applies frequency modulation can also be used.

It is also possible to use a self-excited or separately-excited oscillation circuit whose oscillation frequency can be changed by external human power.

Further, the period setting means fixes the period required for changing the frequency band of the oscillation means of the above embodiment, and sets a pause period for stopping the driving of the oscillation means between the previous period and the next period. Period T required for frequency band change of oscillation means
and the pause period S are set in the routines of step S6 and step 813, but when implementing the present invention,
It can also be implemented as a circuit that opens and closes using a counter and gate circuit.

[Effects of the Invention] As described above, the water droplet removal device for an automobile mirror according to the invention of claim 1 includes an oscillating means for vibrating an ultrasonic vibrator bonded to the back surface of the mirror at a specified frequency, and the oscillating means. frequency range setting means for setting the frequency at which the oscillation means has a variable frequency bandwidth including a plurality of resonant frequencies within that bandwidth; The apparatus further includes cycle setting means for setting two types of cycles, including a pause cycle in which driving of the oscillation means is stopped in between.

Therefore, by shortening the time during which the frequency that moves within the variable frequency bandwidth of the vibration means that vibrates the ultrasonic transducer bonded to the back surface of the mirror stays at the plurality of resonance frequencies, the vibration frequency of the mirror surface can be reduced. The rate of change can be increased, and water droplets and the like can be removed efficiently while reducing power consumption.

For example, even if the ultrasonic vibrator cannot atomize the water droplets on the mirror surface and they are dancing on the mirror surface, the shape of the water droplets that continue to vibrate on the mirror surface will change depending on the rate of change of the vibration frequency of the mirror surface. However, even if atomization is performed using the transverse effect of the mirror surface using an ultrasonic transducer, there will be longitudinal effects with apparently different characteristics at the leading and trailing edges of the frequency change and rest period. However, it can also be added to promote the drop effect of water droplets.

The water droplet removing device for an automobile mirror according to claim 2 is such that the frequency range setting means and the period setting means are constituted by a microcomputer and a D/A converter, and a variable frequency band of an output frequency for vibrating an ultrasonic vibrator is provided. Since the width and the cycle required for changing the frequency band of the oscillation means can be set arbitrarily, settings that take into account the state of adhesion to the surface of the mirror can be made with the same hardware, and can be adapted to the usage environment of the vehicle by simply changing the software. control can be set.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of a control circuit for controlling a water droplet removal device for an automobile mirror according to an embodiment of the present invention, and FIG. 3 is a flowchart of a program for controlling a water droplet removing device for an automobile mirror according to an embodiment of the present invention, and FIG. 4 is a flowchart of a program for controlling a water droplet removing device for an automobile mirror according to an embodiment of the present invention. It is a time chart showing the drive frequency and drive period of the ultrasonic transducer used for control. In the figure, 1: mirror 2: ultrasonic transducer 13: microcomputer 16: D/A converter 17: voltage controlled oscillation circuit 18: transducer drive circuit. In the drawings, the same reference numerals and the same symbols indicate the same or equivalent parts.

Claims (2)

[Claims] (1) An oscillation means that vibrates an ultrasonic transducer bonded to the back surface of the mirror at a specified frequency, and a variable frequency bandwidth that includes a plurality of resonant frequencies within the frequency that vibrates the oscillation means. a frequency range setting means to be set; a period required for changing the frequency band of the oscillating means; and a pause period for stopping the driving of the oscillating means between the period required for changing the frequency band and the period required for changing the next frequency band. 1. A water droplet removing device for an automobile mirror, characterized in that the device comprises a period setting means for repeatedly setting two types of periods. (2) The water droplet removing device for an automobile mirror according to claim 1, wherein the frequency range setting means and the period setting means are constituted by a microcomputer and a D/A converter.