BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention generally relates to an optical device, in particular, to an optical device for fingerprint collection.

2. Description of Related Art

Optical devices such as optical fingerprint collection devices are widely used for fingerprint collection and identification. The collection of fingerprints through optical devices is based on optical imaging the finger surface through optical sensors. Most conventional optical devices for fingerprint collection, such as a reflection type fingerprint reader, use a prism which is directly contacted by a finger of the user, and a light source and an image capture unit is installed at different side of the prism. Through total internal reflection and frustrated total internal reflection (FTIR), the ridge-valley patterns of a fingerprint may produce a high contrast fingerprint image. On the other hand, some optical devices for fingerprint collection use a transmission type fingerprint reader to collect the fingerprint. Light signals are transmitted into the finger and then scattered back to the image capture unit. In certain related arts, the light signals may go through the whole finger.

For an electronic device having fingerprint collection function, how to manufacture an embeddable optical fingerprint collection device that has low cost, strong mechanical strength, and satisfactory sensing quality is one of the most important topics in the pertinent field.

SUMMARY OF THE INVENTION

Accordingly, the invention is directed to an optical device for fingerprint collection, capable of being embedded into an electronic device.

An embodiment of the invention provides an optical device including a first substrate, a light source, a second substrate, an image capturing device, a lens module and a lens holder. The light source is disposed on the first substrate to output a first light beam. The second substrate is disposed above the first substrate. The second substrate includes a first surface and a second surface opposite to the first surface and closer to the first substrate. A scattered light beam which is generated by the first light beam entering an object touching the first surface of the second substrate and scattered in the object is a second light beam. The image capturing device is disposed on the first substrate to receive a third light beam. The third light beam is the second light beam normally incident to the second surface and transmitted to the image capturing device. The lens module is configured to focus the third light beam to be captured by the image capturing device. The lens holder is disposed on the first substrate and located between the light source and the image capturing device. The lens module is disposed on the lens holder.

In an embodiment of the invention, the first light beam is infrared light.

In an embodiment of the invention, the optical device further includes an infrared pass layer. The infrared pass layer is adapted to pass the infrared light and filter out other lights being out of range of wavelength of infrared light.

In an embodiment of the invention, the infrared pass layer is disposed on the image capturing device.

In an embodiment of the invention, the first light beam is visible light.

In an embodiment of the invention, the optical device further includes a visible light pass layer. The visible light pass layer is adapted to pass the visible light and filter out other lights being out of range of wavelength of visible light.

In an embodiment of the invention, the visible light pass layer is disposed on the image capturing device.

In an embodiment of the invention, the optical device further includes a microstructure layer. The microstructure layer is adapted to increase the third light beam and disposed on first surface of the second substrate.

In an embodiment of the invention, the microstructure layer includes a plurality of particles for scattering light.

In order to make the aforementioned and other features and advantages of the invention comprehensible, several embodiments accompanied with figures are described in detail below.

