Abstract:
An exemplary electric shutter comprising a first transparent electrode, an electrochromic layer and a second transparent electrode, wherein said electrochromic layer is disposed between said first transparent electrode and said second transparent electrode, and said second transparent electrode has an opposite polarity to said first transparent electrode. An exemplary camera having such an electric shutter is also provided.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present invention relates generally to the field of imaging, and more particularly, to an electric shutter with an electrochromic layer and a camera having the same. 
         [0003]    2. Description of the Related Art 
         [0004]    A shutter is an essential device in a camera for controlling light exposure time during imaging. A typical shutter is constructed and operated mechanically, in which a number of pieces of metal or plastic are mechanically moved to block or allow light transmission. In order to actuate the pieces of metal or plastic, mechanical elements such as motors and gears are often incorporated in the shutter. 
         [0005]    Cameras with such mechanical shutters suffer from a series of disadvantages. The inclusion of mechanical elements such as motor and gears often leads to difficulty in miniaturization of such cameras. In addition, the complexity of such mechanical shutters often incurs reliability issues for the shutters and the cameras incorporating them. 
         [0006]    Therefore, what is needed is to provide a compact shutter and a camera having the same that is easy to miniaturize and able to work reliably. 
       SUMMARY OF THE INVENTION 
       [0007]    An electric shutter, in accordance with a preferred embodiment, is provided. The electric shutter includes a first transparent electrode, an electrochromic layer and a second transparent electrode. The electrochromic layer is disposed between the first transparent electrode and the second transparent electrode, and the second transparent electrode has an opposite polarity to the first transparent electrode. 
         [0008]    A camera, in accordance with another preferred embodiment, is provided. The camera includes a lens module, an imaging element for sensing light incident thereon, and an electric shutter disposed between the lens module and the imaging element. The electric shutter includes a first transparent electrode, an electrochromic layer and a second transparent electrode. The electrochromic layer is disposed between the first transparent electrode and the second transparent electrode. The second transparent electrode has an opposite polarity to the first transparent electrode. 
         [0009]    A camera in accordance with further another preferred embodiment is provided. The camera includes a lens module, an imaging element for sensing light incident thereon, and an electric shutter. The lens module includes a lens. The electric shutter includes a first transparent electrode, an electrochromic layer and a second transparent electrode. The electrochromic layer is disposed between the first transparent electrode and the second transparent electrode. The second transparent electrode has an opposite polarity to the first transparent electrode. The electric shutter is disposed on a surface of the lens by sequentially forming the first transparent electrode, the electrochromic layer and the second transparent electrode on the surface of the lens. 
         [0010]    In the above-mentioned preferred embodiments, by electrically controlling the transmittance of the electric shutter and thereby electrically controlling the light exposure time of the camera, the necessity of incorporating mechanical components such as motors and gears into the shutter is eliminated. This compact design eases the difficulty of miniaturizing the camera and improves its reliability. 
         [0011]    Other advantages and novel features will become more apparent from the following detailed description of embodiments when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    Many aspects of the present electric shutter and camera can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present electric shutter and camera. 
           [0013]      FIG. 1  is a schematic cross-sectional view of an electric shutter in accordance with a first preferred embodiment; 
           [0014]      FIG. 2  is a schematic cross-sectional view of a camera having an electric shutter as shown in  FIG. 1  in accordance with a second preferred embodiment; 
           [0015]      FIG. 3  is a schematic cross-sectional view of a camera having an electric shutter as shown in  FIG. 1  in accordance with a third preferred embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    Referring to  FIG. 1 , an electric shutter  10 , in accordance with a first preferred embodiment, is provided. The electric shutter  10  includes a first transparent electrode  11 , a second transparent electrode  13  opposing the first transparent electrode  11 , and an electrochromic layer  12  disposed between the first transparent electrode  11  and the second transparent electrode  13 . The second transparent electrode  13  has an opposite polarity to the first transparent electrode  11 . For example, if the first transparent electrode  11  is an anode, the second transparent electrode  13  is correspondingly a cathode, and vice-versa. 
         [0017]    A control circuit is connected to the first transparent electrode  11  and the second transparent electrode  13 . The control circuit includes a power source  14 , a switch  15  and an adjusting element  16 . The power source  14  provides a voltage between the first transparent electrode  11  and the second transparent electrode  13 , forming an electric field therebetween. The switch  15  is normally turned on (connecting state) and the light exposure time can be controlled by the time for which the switch  15  is turned off (disconnecting state). The adjusting element  16  is configured for adjusting the voltage between the first transparent electrode  11  and the second transparent electrode  13  in calibration. 
         [0018]    The first transparent electrode  11  is formed generally by depositing a transparent conductive thin film  112  on a transparent substrate  111 . The second transparent electrode  13  is formed generally by depositing a transparent conductive thin film  132  on a transparent substrate  131 . The transparent conductive thin film  112  or  132  can be a film made of indium tin oxide (ITO). Preferably, the transparent conductive thin films  112  and  132  contact with the electrochromic layer  12 . 
         [0019]    The electrochromic layer  12  is made of an electrochromic material selected from the group consisting of tungsten oxide (WO 3 ), nickel oxide (NiO), vanadium oxide (V 2 O 5 ), and iridium oxide (IrO 2 ). The transmittance of the electrochromic layer varies in response to an external voltage applied thereto and the color that the electrochromic layer turns into normally depends on the material composition thereof. If multiple electrochromic materials that can transmit light of different wavelengths are combined in use in the electrochromic layer  12 , the transmission of light of all the wavelengths in visible spectrum can be controlled. Preferably, the electrochromic layer  12  can be developed by mixing different electrochromic materials and forming a film of the mixture, or alternatively by superposing films of different electrochromic materials. 
         [0020]    Referring to  FIG. 2 , a camera  100 , in accordance with a second preferred embodiment, is provided. The camera  100  includes an imaging element  30 , a lens module  20  and an electric shutter  10 . The electric shutter  10  is the same as the electric shutter in the first preferred embodiment and disposed between the lens module  20  and the imaging element  30 . 
         [0021]    The imaging element  30  can be a CCD (charge-coupled device) or CMOS (complementary metal oxide semiconductor) image sensor, or an image film. Preferably, a transparent board  31  is disposed on a side of the imaging element  30  near to the lens module  20  for preventing dirt and dusts from contaminating the imaging element  30 . To simplify the structure of camera  100 , the electric shutter  10  is disposed on the transparent board  31  by sequentially forming the first transparent electrode  11 , the electrochromic layer  12  and the second transparent electrode  13  on the transparent board  31 . The control circuit for controlling the electric shutter  10  and a control circuit for controlling the imaging element  30  can be integrated onto a printed circuit board (not shown). 
         [0022]    The lens module  20  includes a lens barrel  21 , a lens  22 , and another lens  23 . The lenses  22  and  23  are sequentially arranged in the lens barrel  21  along a direction oriented from an object side to an image side of the lens module  20 . The lens  22  includes an optical part  221 , which optically contributes to imaging and a non-optical part  222 , which does not optically contribute to imaging. 
         [0023]    It is understandable that if the imaging element is a semiconductor image sensor, the electric shutter  10  can be disposed on a surface of the imaging element  30  facing toward the lens module  20  by sequentially forming the first transparent electrode  11 , the electrochromic layer  12  and the second transparent electrode  13  thereon. 
         [0024]    Referring to  FIG. 3 , a camera  200 , in accordance with a third preferred embodiment, is provided. The camera  200  includes an imaging element  30 , a lens module  20  and an electric shutter  10 , similar to the camera  100  described in the second preferred embodiment. The difference of the camera  200  and the camera  100  in the second preferred embodiment is that in the camera  200 , the electric shutter  10  is disposed on a surface of lens  22  by sequentially forming the first transparent electrode  11 , the electrochromic layer  12  and the second transparent electrode  13  thereon. Preferably, the surface that the electric shutter  10  is disposed on faces the object side of the lens  22 . 
         [0025]    It is understandable that the electric shutter  10  can be disposed at other locations in the camera  200  between the object to be photographed and the imaging element  30 , as long as the light coming from an object passes through the electric shutter  10  before it is incident on the imaging element  30  and forms an image of the object thereon. 
         [0026]    In the above-mentioned preferred embodiments, by electrically controlling the transmittance of the electric shutter  10  and thereby electrically controlling the light exposure time of the camera  100  or  200 , the necessity of incorporating mechanical components such as motors and gears into the shutter  10  is eliminated. This compact design eases the difficulty to miniaturize the camera  100  or  200  and improves its reliability. 
         [0027]    It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the present invention.