CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese Patent Application No. 2015-251914 filed on Dec. 24, 2015 and is a Continuation Application of PCT Application No. PCT/JP2016/086933 filed on Dec. 12, 2016. The entire contents of each application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a vibrating device including a piezoelectric vibrator, a method for driving the vibrating device, and a camera.

2. Description of the Related Art

Monitoring devices, such as cameras, are required to have a constantly clear field of view. In particular, for outdoor cameras, such as car-mounted cameras, various mechanisms for removing water droplets, such as raindrops, have been proposed. Japanese Unexamined Patent Application Publication No. 2012-138768 describes a camera with a raindrop-removing function including a dome-shaped cover disposed in front of a camera main body. The dome-shaped cover is coupled to a cylindrical portion. A piezoelectric vibrator is fixed to an inner side surface of the cylindrical portion. The piezoelectric vibrator vibrates the cylindrical portion and the dome-shaped cover. Thus, raindrops on the dome-shaped cover are removed. According to Japanese Unexamined Patent Application Publication No. 2012-138768, vibration nodes of the dome-shaped cover can be changed by changing the applied frequency, so that the positions from which the raindrops are removed can be changed.

Japanese Unexamined Patent Application Publication No. 2007-82062 describes a camera with a raindrop removing function including a piezoelectric vibrator, an adhesive, and an outer lens disposed in front of a camera main body. When raindrops adhere to the outer lens, an ultrasonic transducer is driven to vibrate the outer lens. The raindrops are removed or atomized into mist that dissipates due to the vibration.

In the structures described in Japanese Unexamined Patent Application Publication No. 2012-138768 and Japanese Unexamined Patent Application Publication No. 2007-82062, the piezoelectric vibrator is driven to remove the raindrops by causing the dome-shaped cover or the outer lens to mechanically resonate. The water droplets evaporate from liquid to gas due to the mechanical resonance, and are thereby removed. However, in the above-described water-droplet-removing method using the mechanical resonance, the dome-shaped cover or the outer lens always has portions that define vibration nodes. Therefore, there is a problem in that the water droplets cannot be removed from the portions that define the vibration nodes.

To solve this problem, according to Japanese Unexamined Patent Application Publication No. 2012-138768, for example, the vibration mode is changed to change the positions of the vibration nodes. However, when the water droplets on the dome-shaped cover are in a region within the field of view of the camera, there is a risk that the field of view of the camera will become unclear due to the mist generated when the water droplets are removed. In addition, there is also a risk that residue of the water droplets will remain on the dome-shaped cover or the outer lens at positions at which the water droplets are atomized. Thus, even when the water droplets can be removed from the portions that define the vibration nodes, the clarity of the field of view of the camera cannot always be improved. Furthermore, substances to be removed include not only water droplets but also solutions other than water, such as ethanol, aqueous solutions of salt, an antifreezing agent (calcium chloride), etc., droplets of liquid containing water insoluble impurities, such as mud water, and colloidal solutions, such as coffee.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide vibrating devices and cameras capable of removing water droplets or other substances from a dome-shaped cover or an outer lens and maintaining the clarity of the field of view of the camera. In addition, preferred embodiments of the present invention provide methods for driving a vibrating device capable of removing water droplets or other substances from a dome-shaped cover or an outer lens and maintaining the clarity of the field of view of a camera.

According to a preferred embodiment of the present invention, a vibrating device for a camera including a lens includes a tubular vibrating body and a lens cover. The tubular vibrating body includes a first surface, a second surface that is opposite the first surface, and a side wall portion that connects the first and second surfaces. The first and second surfaces include openings. The lens cover covers one of the openings in the tubular vibrating body. The tubular vibrating body includes a tubular member and a piezoelectric vibrator fixed to the tubular member. The lens cover includes a tubular mode changing coupler coupled to the tubular vibrating body and a light transmitting body unit joined to the mode changing coupler at a side opposite to a side at which the tubular vibrating body is coupled. The light transmitting body unit includes a light transmitting portion disposed in front of the lens. The mode changing coupler includes a thin portion having a thickness smaller than a thickness of the tubular member.

In a vibrating device according to a preferred embodiment of the present invention, when the tubular vibrating body is vibrated, the tubular vibrating body vibrates the light transmitting body unit in a first vibration mode in which the light transmitting body unit has a vibration node in a first region of the light transmitting body unit, the first region corresponding to a field-of-view section of the camera, and a vibration antinode in a second region of the light transmitting body unit, the second region being positioned outside the field-of-view section of the camera.

In a vibrating device according to a preferred embodiment of the present invention, a plurality of the piezoelectric vibrators are arranged in a circumferential direction of the tubular member so that the light transmitting body unit includes a plurality of vibration regions when the tubular vibrating body is vibrated, and that among the vibration regions, vibration regions that are adjacent to each other vibrate in opposite phases.

In a vibrating device according to a preferred embodiment of the present invention, the piezoelectric vibrator is arranged so as to extend in a circumferential direction of the tubular member and polarized in a thickness direction of the piezoelectric vibrator non-uniformly in the circumferential direction so that the light transmitting body unit includes a plurality of vibration regions when the tubular vibrating body is vibrated, and that among the vibration regions, vibration regions that are adjacent to each other vibrate in opposite phases.

In a vibrating device according to a preferred embodiment of the present invention, when the lens of the camera is viewed from the light transmitting body unit in the first vibration mode, a node of the first vibration mode is positioned on the light transmitting body unit in a region that overlaps the lens. In this case, a water droplet or other substance that has adhered to the light transmitting body unit in the region that overlaps the lens is able to be more reliably moved out of the first region of the light transmitting body unit that corresponds to the field-of-view section of the camera, and the clarity of the field of view of the camera is able to be maintained.

In a vibrating device according to a preferred embodiment of the present invention, the tubular vibrating body vibrates the light transmitting body unit in a second vibration mode in which a water droplet or other substance is atomized in the second region of the light transmitting body unit. In this case, when the water droplet or other substance that has been moved is atomized in the region outside the field-of-view section, the clarity of the field of view of the camera is able to be maintained even before the atomization.

In a vibrating device according to a preferred embodiment of the present invention, an amplitude in the second vibration mode is greater than an amplitude in the first vibration mode. In this case, the water droplet or other substance is able to be more reliably atomized.

In a vibrating device according to a preferred embodiment of the present invention, the lens cover and the lens may be spaced from each other.

A camera according to a preferred embodiment of the present invention includes a camera main body including a lens module and a vibrating device according to a preferred embodiment of the present invention. The lens module is disposed in the lens cover.

Another camera according to a preferred embodiment of the present invention includes a camera main body including a lens module including a lens positioned at a front end; and a tubular vibrating body coupled to the lens module and including a tubular piezoelectric vibrator and first and second surfaces that oppose each other. The tubular piezoelectric vibrator includes a plurality of vibration regions arranged in a circumferential direction thereof and is structured so that among the vibration regions, vibration regions that are adjacent to each other vibrate in opposite phases. When the tubular vibrating body is vibrated, the tubular vibrating body vibrates the lens module in a first vibration mode in which the lens positioned at the front end has a vibration node in a first region of the lens, the first region corresponding to a field-of-view section of the camera, and a vibration antinode in a second region of the lens, the second region being positioned outside the field of view of the camera.

According to a preferred embodiment of the present invention, a method for driving a vibrating device according to a preferred embodiment of the present invention includes a step of moving a water droplet or other substance that has adhered to the light transmitting body unit in the first region to the second region outside the field-of-view section of the camera by vibrating the light transmitting body unit in the first vibration mode; and a step of atomizing the water droplet moved to the second region of the light transmitting body unit.

In a method according to a preferred embodiment of the present invention, in the atomizing step, the water droplet or other substance moved to the second region of the light transmitting body unit is atomized by vibrating the light transmitting body unit in the second vibration mode. In this case, the water droplet or other substance is able to be more quickly moved toward the second region of the light transmitting body unit, and the clarity of the field of view of the camera is able to be maintained.

With the vibrating devices, the methods for driving the driving method, and the cameras according to preferred embodiments of the present invention, the water droplet or other substance that has adhered to the lens cover or the lens exposed to the outside of the lens module is able to be moved out of the first region of the light transmitting body unit that corresponds to the field-of-view section of the camera. Then, removal of the water droplet or other substance is performed in the second region of the light transmitting body unit that corresponds to the region outside the field-of-view section of the camera. Thus, the water droplet or other substance is able to be removed from the dome-shaped cover or the outer lens, and the clarity of the field of view of the camera is able to be maintained.

The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.

