Ultrasonic wiper

An ultrasonic wiper for conveying a fluid off of a windshield glass of a vehicle characterized by comprising ultrasonic oscillators which excite progressive waves in the glass in a predetermined directional movement.

BACKGROUND OF THE INVENTION 
The present invention relates to a wiper used for automobiles which is 
adapted to wipe rain and snow from a windshield by means of ultrasonic 
oscillation. 
Automobiles and streetcars are generally provided with a so-called wiper 
apparatus for producing the reciprocating angular movement of a blade by 
means of a link mechanism. 
Since a conventional wiper is, so to speak, of a mechanical type, there are 
various problems in that such components as the motor, etc., are large in 
number and the blades employed are often damaged and worn. 
In addition, there is the problem that a blade reciprocating on a 
windshield surface interrupts the vision of the driver and is thus 
unsuitable for safe driving. 
In consideration of the above problems, a blade-less wiper has been 
proposed (Japanese Patent Publication No. 1760/1962) in which magnetic 
oscillation is provided on the glass of a windshield in the longitudinal 
direction so that water droplets adhered thereto are scattered, but this 
proposal has not been put into practice. 
The present invention has been achieved with a view to providing a wiper 
which has none of the above-described problems as experienced in the 
conventional mechanical wiper and which adopts a completely different 
approach from simple addition of oscillation. The invention is 
characterized by comprising ultrasonic oscillators which excite 
progressive waves moving from one side to the other of a windshield glass 
of a vehicle such as an automobile on the outside surface thereof.

FIG. 1 is a sectional side view showing the structural concept of a wiper 
of the present invention. In this drawing, reference number 1 denotes the 
side section of the body of an automobile; reference number 2, a front 
windshield glass; and reference numbers 3, 4, ultrasonic oscillators 
provided on the inner surface (inner side of the vehicle) of the glass, 
two Langevin longitudinal oscillators 31, 41 being disposed such as to 
abut against the glass through horn-type transformers 32, 42, 
respectively. 
Each of the oscillators 31, 41 is itself supported by a suitable holder or 
housing (not shown) at the nodal point of oscillation, the holder or the 
housing being mounted on the body side of an automobile. In this drawing, 
reference numbers 33, 43 denote an ultrasonic oscillating circuit and 
receiving circuit, respectively. 
When the oscillator 31 is driven, ultrasonic oscillation excites surface 
progressive waves on the outer surface of the glass and these progressive 
waves are received by the oscillator 41. When the outer surface 2a of the 
glass is now observed, material points on the surface oscillate reversely 
(counterclockwise) relative to the progressive direction of the waves 
(upward), and rain and snow R adhered on the surface of the glass 2 are 
thus subjected to thrust through frictional force between the glass 
surface 2a and the adhered substances in the direction opposite to the 
progressive direction of the waves, the rain and snow thereby being caused 
to fall downwardly on the glass (refer to FIG. 2). 
Therefore, if the relationship between the oscillators 3, 4 is reversed, 
rain and snow on the glass are subjected to upward thrust. 
Consequently, the following method of employing the wiper of the present 
invention shows great benefits. 
When a vehicle is running at low speed, the oscillator 3 is driven and the 
oscillator 4 receives waves, so that downward thrust acts on rain and snow 
adhered on the glass surface, thereby leading to the synergism which is 
created by the tendency of the rain and snow to fall by virtue of their 
own weight and the movement of the surface progressive waves. 
When a vehicle is running at high speed, the relationship between the 
oscillator 3 and the oscillator 4 is reversed so that rain and snow 
adhered on the glass surface has the tendency to move upwardly on the 
glass by the effect of wind pressure and the inertial function, and thus 
the synergism created by this tendency and the surface progressive waves 
brings about an extremely effective action for removing the adhered rain 
and snow. 
In the present invention, the oscillators for exciting the progressive 
waves on the surface of the glass may be directly fixed to the surface of 
the glass without use of a transformer or a transmitter. 
FIG. 3 shows another embodiment which, for example, includes nine 
electrodes 52 provided in parallel on the surface of a piezoelectric body 
51 adhered to the inner surface of the glass 2, these electrodes 52 being 
divided into three circuits and connected to a phase converter 53 in which 
they are connected to a high frequency electrical power source 54 with the 
phase of each circuit shifted 120 degrees with respect to the others. By 
this means, progressive waves are generated in the direction of the 
movement shown by the arrow in the drawing. The progressive direction of 
the waves is reversed by reversing the phase shift of the phase converter. 
The wiper comprised as described above carries rain droplets adhered to the 
surface of the glass 2 or becoming adhered thereto by means of the 
function of the progressive waves through the frictional force between the 
glass surface and the adhered substances, or thereby prevents them from 
adhering to the surface. 
The wiper of the present invention can of course be applied to the front 
windshield glass of an automobile, as well as to the side or rear thereof 
or to the window glass of buildings. 
As described above, since the wiper of the present invention is so 
constructed that progressive waves are excited on the surface of the front 
windshield glass of an automobile by ultrasonic oscillation, rain droplets 
adhered to the glass or becoming adhered thereto are carried by means of 
the function of the progressive waves or prevented from adhering thereto, 
and thus it becomes unnecessary to employ a blade-type wiper which 
reciprocates when driven by a motor.