FOREIGN SUBSTANCE REMOVING APPARATUS

Abstract

A foreign substance removing apparatus that can provide the desired vibration amplitude to a light transmitting member, without using a large driving voltage. The foreign substance removing apparatus removes foreign substances adhered to a surface of an optical member disposed in a light ray incident path and includes a piezoelectric element fixed to a first plane of the optical member, a circular disk fixed to a second plane, opposite from the first plane, of the optical member so as to face the piezoelectric element, and a driving unit for applying an AC voltage to the piezoelectric element to cause the optical member to elastically vibrate in a direction perpendicular to the planes thereof, thereby removing the foreign substances adhered to the surface of the optical member.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a plan view showing the construction of a foreign substance removing apparatus according to a first embodiment of the present invention;

FIG. 1B is a side view of the foreign substance removing apparatus;

FIG. 1C is a view showing a displacement distribution in a vibration mode of the foreign substance removing apparatus;

FIG. 1D is a view showing a displacement distribution in another vibration mode of the foreign substance removing apparatus;

FIG. 2 is a perspective view showing the foreign substance removing apparatus in a state mounted to a reader section of a copying machine;

FIG. 3A is a fragmentary section view, taken along an X-Z plane of the foreign substance removing apparatus shown in FIGS. 1A to 1D, showing part of an optical member near a piezoelectric element and a circular plate;

FIG. 3B is a strain distribution diagram for the optical member;

FIG. 4 is an exploded perspective view showing the construction of a foreign substance removing apparatus according to a second embodiment of the present invention;

FIG. 5A is a plan view of an optical filter, a piezoelectric element, and an elastic member that are shown in FIG. 4;

FIG. 5B is a side view of the optical filter, the piezoelectric element, and the elastic member;

FIG. 5C is a view showing a displacement distribution in a vibration mode in which the optical filter is caused to vibrate;

FIG. 5C is a view showing a displacement distribution in another vibration mode in which the optical filter is caused to vibrate;

FIG. 6 is an exploded perspective view showing the construction of a foreign substance removing apparatus according to a third embodiment of the present invention;

FIG. 7 is an exploded perspective view showing the construction of a foreign substance removing apparatus according to a fourth embodiment of the present invention;

FIG. 8 is a perspective view of a conventional image reading apparatus;

FIG. 9A is a view showing an ADF platen;

FIG. 9B is a view showing a bending vibration produced in the ADF platen in FIG. 9A by means of a piezoelectric element;

FIG. 9C is a view showing another bending vibration in the ADF platen;

FIG. 9D is a view showing a bending vibration displacement distribution in the ADF platen;

FIG. 10A is a fragmentary section view, taken along an X-Z plane of the conventional foreign substance removing apparatus in FIG. 8, showing part of the ADF platen near the piezoelectric element;

FIG. 10B is a view showing an X-directional strain in the ADF platen and the piezoelectric element;

FIG. 11 A is a fragmentary section view, taken along an X-Z plane of the conventional foreign substance removing apparatus in FIG. 8, showing part of the ADF platen at a location away from the piezoelectric element in the X direction; and

FIG. 11B is a view showing an X-directional strain in the ADF platen and the piezoelectric element.

Claims

1. A foreign substance removing apparatus for removing foreign substances adhered to a surface of a plate-like light transmitting member disposed in a light ray incident path, comprising: an electromechanical energy conversion element fixed to a first plane of said light transmitting member;an elastic member fixed to a second plane of said light transmitting member so as to face said electromechanical energy conversion element, the second plane being opposite from the first plane; andan AC voltage applying circuit for applying an AC voltage to said electromechanical energy conversion element to cause said light transmitting member to elastically vibrate in a direction perpendicular to the planes thereof, thereby removing the foreign substances adhered to the surface of said light transmitting member.

2. The foreign substance removing apparatus according to claim 1, wherein a projected shape of said elastic member on said light transmitting member is in coincidence with a projected shape of said electromechanical energy conversion element on said light transmitting member.

3. The foreign substance removing apparatus according to claim 1, further including: a support fixing member formed integrally with said elastic member for supporting and fixing said light transmitting member.

4. The foreign substance removing apparatus according to claim 1, wherein said electromechanical energy conversion element is formed by a plate-like piezoelectric material, and said elastic member is formed by a plate-like material.

5. The foreign substance removing apparatus according to claim 1, said elastic member has a thickness thereof made larger than that of said electromechanical energy conversion element when said electromechanical energy conversion element has its Young's modulus larger than that of said elastic member, and said elastic member has a thickness thereof made smaller than that of said electromechanical energy conversion element when said electromechanical energy conversion element has its Young's modulus smaller than that of said elastic member.

6. The foreign substance removing apparatus according to claim 1, wherein at least one of material and thickness of said elastic member is set such that a product of a Yong's modulus of said electromechanical energy conversion element and a geometrical moment of area thereof with respect to an axis extending in a direction perpendicular to a thickness direction of said light transmitting member and passing through a center of said light transmitting member in the thickness direction thereof is made equal to a product of a Young's modulus of said elastic member and a geometrical moment of area thereof with respect to the axis.

7. The foreign substance removing apparatus according to claim 1, wherein said elastic member is formed by a piezoelectric material.

8. The foreign substance removing apparatus according to claim 1, wherein said light transmitting member functions as a low pass filter.