Optical excitation device, light source module, and projector using the same

An optical excitation device for exciting a laser light source includes a wavelength converter and a moving element. The laser light source emits a first light beam. The wavelength converter includes a wheel, a motor connected to the wheel, and a wavelength converting layer disposed on a light receiving surface of the wheel for converting the first light beam with the first wavelength into a second light beam with a second wavelength. The moving element is connected to the wavelength converter for moving the wavelength converter relative to the laser light source. There is a first reaction area between the laser light source and the wavelength converter when only the motor is operated, there is a second reaction area between the laser light source and the wavelength converter when both the motor and the moving element are operated, and the second reaction area is greater than the first reaction area.

RELATED APPLICATIONS

This application claims priority to Taiwan Application Serial Number 101147403, filed Dec. 14, 2012, which is herein incorporated by reference.

BACKGROUND

1. Field of Invention

The present invention relates to an optical excitation device. More particularly, the present invention relates to an optical excitation device utilized in a projector.

2. Description of Related Art

Optical projectors have been applied in many fields since first being developed. They serve an expanded range of purposes, from use in consumer products to use in high-tech devices. For example, optical projectors may be used in projective systems for projecting enlarged images to facilitate the giving of presentations during conferences, or they may be used in projection screens or televisions for projecting and displaying real-time images.

A conventional projector typically includes a light source module and an image processor. The light emitted from the light source module is collected by optical components and is processed by a filter and a color wheel. The processed light is supplied to the image processor and subsequently projected onto a projection screen.

With the continued development of projectors, a laser light source and a phosphor wheel are now utilized in the light source module for providing light beams with various wavelengths. However, the energy carried by the laser light beam is high and focused, and as a result, the temperature of the wheel may reach up to 1000° C. after receiving the laser light beam for a period of time. Therefore, the phosphor on the phosphor wheel may be damaged. As brightness requirements for projectors continue to increase, so does the energy carried by laser light beams generated therein. Hence, the problem of phosphor damage due to high temperatures is becoming increasingly severe.

SUMMARY

The invention provides an optical excitation device with enhanced thermal dissipating efficiency.

An aspect of the invention provides an optical excitation device for exciting a laser light source. The laser light source emits a first light beam having a first wavelength. The optical excitation device includes a wavelength converter and a moving element. The wavelength converter includes a wheel, a motor connected to the wheel for driving the wheel to rotate relative to the laser light source, and a wavelength converting layer disposed on a light receiving surface of the wheel for converting the first light beam with the first wavelength into a second light beam with a second wavelength. The moving element is connected to the wavelength converter for moving the wavelength converter relative to the laser light source. There is a first reaction area between the laser light source and the wavelength converter when the motor is operated and the moving element is not operated, there is a second reaction area between the laser light source and the wavelength converter when both the motor and the moving element are operated, and the second reaction area is greater than the first reaction area.

In one or more embodiments, a projection path of the laser light source on the wavelength converter is located within a coating area of the wavelength converting layer.

In one or more embodiments, the wheel comprises a front surface, a back surface, and a side surface connecting the front surface and the back surface, the motor is disposed at the back surface, and the light receiving surface is the front surface.

In one or more embodiments, the light receiving surface is arranged perpendicular to a light emitting direction of the laser light source.

In one or more embodiments, the light receiving surface is arranged obliquely to a light emitting direction of the laser light source.

In one or more embodiments, the moving element is a robot arm for swinging the wheel relative to the laser light source.

In one or more embodiments, the wheel comprises a front surface, a back surface, and a side surface connecting the front surface and the back surface, the motor is disposed at the back surface, and the light receiving surface is the side surface.

In one or more embodiments, the wavelength converter has a rotation cycle and a movement cycle, and the movement cycle is less than or greater than an integer multiple of the rotation cycle.

In one or more embodiments, a light emitting direction of the laser light source is along a z-axis direction, and a center of the wheel is at least moved on an x-y plane.

Another aspect of the invention provides a light source module. The light source module includes a laser light source and an optical excitation device. The laser light source emits a first light beam having a first wavelength. The optical excitation device includes a wavelength converter and a moving element. The wavelength converter includes a wheel, a motor connected to the wheel for driving the wheel to rotate relative to the laser light source, and a wavelength converting layer disposed on a light receiving surface of the wheel for converting the first light beam with the first wavelength into a second light beam with a second wavelength. The moving element is connected to the wavelength converter for moving the wavelength converter relative to the laser light source. There is a first reaction area between the laser light source and the wavelength converter when the motor is operated and the moving element is not operated, there is a second reaction area between the laser light source and the wavelength converter when both the motor and the moving element are operated, and the second reaction area is greater than the first reaction area.

In one or more embodiments, a projection path of the laser light source on the wavelength converter is located within a coating area of the wavelength converting layer.

In one or more embodiments, the wheel comprises a front surface, a back surface, and a side surface connecting the front surface and the back surface, the motor is disposed at the back surface, and the light receiving surface is the front surface.

In one or more embodiments, the light receiving surface is arranged perpendicular to a light emitting direction of the laser light source.

In one or more embodiments, the light receiving surface is arranged obliquely to a light emitting direction of the laser light source.

In one or more embodiments, the moving element is a robot arm for swinging the wheel relative to the laser light source.

In one or more embodiments, the wheel comprises a front surface, a back surface, and a side surface connecting the front surface and the back surface, the motor is disposed at the back surface, and the light receiving surface is the side surface.

In one or more embodiments, the wavelength converter has a rotation cycle and a movement cycle, and the movement cycle is less than or greater than an integer multiple of the rotation cycle.

In one or more embodiments, a light emitting direction of the laser light source is along a z-axis direction, and a center of the wheel is at least moved on an x-y plane.

Another aspect of the invention provides a projector utilizing the optical excitation device.

Another aspect of the invention provides a projector utilizing the light source module.

The projection path of the laser light source on the wavelength converter can be expanded by moving the wavelength converter relative to the laser light source. Therefore, the reaction area between the laser light source and the wavelength converter can be enlarged, and the wavelength converting layer can be utilized more efficiently. The energy carried by the laser light beam can be distributed on the wavelength converter more equally, thereby increasing the thermal dissipating efficiency of the wavelength converter. Moreover, a situation in which the wavelength converting layer is damaged due to high temperatures can be prevented.

DESCRIPTION OF THE EMBODIMENTS

FIG. 1is a side view of an embodiment of a light source module of the invention. The light source module100includes a laser light source110and an optical excitation device. The optical excitation device includes a wavelength converter120and a moving element150. The light source module100utilizes the moving element150for moving the wavelength converter120relative to the laser light source110, such that a projection path of the laser light source110on the wavelength converter120can be expanded, and a reaction area of a first light beam112emitted from the laser light source110on the wavelength converter120can be increased. The reaction area of the first light beam112is equal to a total area of a projection path the laser light beam (i.e., the first light beam112) emitting on the wavelength converting layer140. As a result of such expansion of the projection path of the laser light source110, the wavelength converter120can be utilized more efficiently. Moreover, the energy of the laser light source110can be distributed on the wavelength converter120more uniformly, and the heat dissipating efficiency of the wavelength converter120can be improved.

The laser light source110emits the first light beam112having a first wavelength. The first light beam112provided by the laser light source110is emitted onto the wavelength converter120. The wavelength converter120includes a wheel122, a motor130connected to the wheel122, and a wavelength converting layer140disposed on the wheel122. The wheel122has a front surface124, a back surface126, and a side surface128connecting the front surface124and the back surface126. The motor130is disposed at the back surface126of the wheel122, and has a shaft132. The shaft132of the motor130is connected to the wheel122for driving the wheel122to rotate. The wavelength converting layer140is disposed on the front surface124of the wheel122. Namely, the front surface124of the wheel122is a light receiving surface for receiving the first light beam112, and the light receiving surface is arranged substantially perpendicularly to the laser light source110.

The laser light source110is disposed at a fixed position in some embodiments. The first light beam112provided by the laser light source110is emitted onto the wavelength converting layer140of the wavelength converter120, and then the first light beam112becomes a second light beam114having a second wavelength after passing through the wavelength converter120, in which the second wavelength is different from the first wavelength. The wavelength converting layer140can be a mixture of a wavelength converting material and a polymer adhesive. The wavelength converting layer140is coated on a predetermined zone of the wheel122, in which the predetermined zone is ring-shaped with an empty portion in the center for disposing the motor130. The wavelength converting material can be selected from the group consisting of phosphor, sensitive material, fluorescent color-conversion-media, organic complex, self-luminous pigment, quantum-dots-based material, quantum-wire-based material, quantum-well-based material, and combinations thereof.

The moving element150is connected to the wavelength converter120for moving the wavelength converter120relative to the laser light source110. The moving element150can be a robot arm, a sliding block and a rail, a gear and a rack, or other mechanisms. Therefore, the wavelength converter120not only rotates relative to the laser light source110by the motor130but also moves relative to the laser light source110by the moving element150. In some embodiments, the motor130can be integrated into the moving element150. In other embodiments, the motor130and the moving element150can be separate elements.

When the wavelength converter120is only rotated rapidly by the motor130, the projection path (e.g., the reaction area of the wavelength converter120) is a circle with a single radius, and a line width of the circle is approximately the same as a line width of the first light beam112. When the wavelength converter120is further moved relative to the laser light source110by the moving element150, the projection path of the first light beam112on the wavelength converter120can be expanded to form a regular or an irregular pattern. Compared to when only rotating the wavelength converter120, both rotating and moving the wavelength converter120at the same time may increase the reaction area between the first light beam112emitted from the laser light source110and the wavelength converter120. Hence, the high energy of the laser light beam (i.e., the first light beam112) can be distributed on the wavelength converter120more uniformly, thereby increasing the heat dissipating efficiency of the light source module100. Additional details are provided below with reference to the drawings.

FIG. 2is a front view of a projection path of a light source on a wavelength converter in a conventional light source module. In the case of the conventional wavelength converter10, a coating area A1of a wavelength converting layer14is only arranged at a circular edge of a wheel12. A projection path P1of the light source is a circle with a single radius. There is a first reaction area between the laser light source and the wavelength converter10. The reaction area is a sum of the projection path P1, which is approximately the same as the perimeter of the circle.

FIG. 3is a front view of an embodiment of a projection path of the laser light source110on the wavelength converter120of the invention. Referring toFIGS. 1 and 3, the wavelength converter120is connected to the moving element150. The wavelength converter120not only rotates but also moves relative to the laser light source110. A coating area A2of the wavelength converting layer140on the wheel122is extended inwardly from an edge of the wheel122to enlarge a reaction area between the first light beam112from the laser light source110and the wavelength converter120. For example, the wavelength converter120is rotated and is moved left-and-right (along the x direction as indicated inFIG. 1) relative to the laser light source110. The projection path P2of the first light beam112on the wavelength converter120is a combination of plural circles, the resulting formation of which is similar to an ellipse. There is a second reaction area between the laser light source110and the wavelength converter120, and the area of the second reaction area is a sum of the perimeter of the circles. The second reaction area is greater than the first reaction area as shown inFIG. 2. The second reaction area is smaller than the coating area A2of the wavelength converting layer140on the wheel122.

In the case ofFIG. 2, there is a first reaction area between the laser light source and the wavelength converter10when a motor is operated and a moving element is not utilized. In contrast, in the case of the invention, with reference toFIGS. 1 and 3, there is a second reaction area between the laser light source110and the wavelength converter120when both the motor130and the moving element150are operated. The second reaction area is greater than the first reaction area, as mentioned above. Moreover, as discussed with reference toFIG. 3, the wavelength converter120is moved relative to the laser light source110by the moving element150, and as a result, the reaction area between the first light beam112and the wavelength converter120can be enlarged to thereby distribute the energy of the laser light beam on the surface of the wheel122more uniformly. Ultimately, this increases the heat dissipating efficiency of the wavelength converter120. Moreover, the problem of damage to wavelength converting material as a result of being exposed to high temperatures can be prevented, and the area of the wheel122can be utilized more efficiently.

Referring back toFIG. 1, the wavelength converter120may be moved relative to the laser light source110in a variety of different ways, as long as the projection path of the first light beam112on the wavelength converter120is expanded, and is located within the coating area of the wavelength converting layer140. The factors that determine the projection path of the first light beam112on the wavelength converter120include a moving distance of the wavelength converter120, a moving cycle for completing a full movement of the wavelength converter120, a radius of the wheel122, a landing point of the first light beam112on the wavelength converter120, a speed of the motor130, an angular speed of the wavelength converter120, and a rotation cycle of the wavelength converter120. The projection path can be designed by adjusting these factors. A description in this regard will be provided with reference toFIG. 4AtoFIG. 4E.

FIG. 4AtoFIG. 4Eare schematic diagrams for describing different embodiments of a projection path of the laser light source110on the wavelength converter120of the invention. With reference also toFIG. 1, it is noted that the laser light source110is fixed at a predetermined position and emits the first light beam112, and the wavelength converter120is rotated relative to the laser light source110. The patterns illustrated inFIG. 4AtoFIG. 4Eare the projection paths of the laser light source110projecting on the wavelength converter120when the wavelength converter120is rapidly rotated relative to the laser light source. The patterns of the projection paths are formed by projected laser points from the laser light source110on the wavelength converter120.

For example, when the wavelength converter120is moved relative to the laser light source110left and right only, and the rotation cycle of the wavelength converter120is smaller than the movement cycle of the wavelength converter120, the projection path P2of the laser light source110on the wavelength converter120is in the form of a lateral ellipse, as shown inFIG. 4A.

When the wavelength converter120is moved relative to the laser light source110up and down only, and the rotation cycle of the wavelength converter120is smaller than the movement cycle of the wavelength converter120, the projection path P3of the laser light source110on the wavelength converter120is in the form of a vertical ellipse, as shown inFIG. 4B.

When the wavelength converter120is moved relative to the laser light source110both left and right and up and down, and the rotation cycle of the wavelength converter120is smaller than the movement cycle of the wavelength converter120, the projection path P4of the laser light source110on the wavelength converter120is in the form of a plurality of partially overlapping circles, as shown inFIG. 4C.

When the rotation cycle of the wavelength converter120is larger than the movement cycle of the wavelength converter120, the projection path P5of the laser light source110on the wavelength converter120is in the form of a circular zigzag pattern, as shown inFIG. 4D.

When the wavelength converter120is moved relative to the laser light source110left and right, and the rotation cycle of the wavelength converter120is similar to the movement cycle of the wavelength converter120, the projection path P6of the laser light source110on the wavelength converter120is in the form of a plurality of partially overlapping ellipses, as shown inFIG. 4E.

Generally speaking, the moving distance on a plane of the wavelength converter120must be smaller than a coating width of the wavelength converting layer140, and the movement cycle of the wavelength converter120is not an integer multiple of the rotation cycle (i.e., is greater than or less than an integer multiple of the rotation cycle). The projection path of the laser light source110on the wavelength converter120can be expanded by such design.

FIG. 5AtoFIG. 5Care side views of different embodiments of the light source module100of the invention. As shown inFIG. 5A, the wavelength converter120is moved relative to the laser light source110up and down by the moving element150, as indicated by the arrow inFIG. 5A. The moving element150can be a robot arm, a sliding block and a rail, a gear and a rack, or other possible mechanisms.

As shown inFIG. 5B, the wavelength converter120is moved relative to the laser light source110obliquely by the moving element150, as indicated by the arrow inFIG. 5B. The moving element150can be a robot arm, a sliding block and a rail, a gear and a rack, or other possible mechanisms.

As shown inFIG. 5C, the wavelength converter120is swung relative to the laser light source110front and back vertically by the moving element150, as indicated by the arrow inFIG. 5C. The moving element150can be a robot arm. The center125of the wheel122is utilized as a pivot point, and the wheel122is swung back and forth vertically relative to the laser light source110by the moving element150about the center125of the wheel122.

FIG. 5DandFIG. 5Eare top views of different embodiments of the light source module100of the invention. As shown inFIG. 5D, the wavelength converter120is moved relative to the laser light source110left and right by the moving element150, as indicated by the arrow inFIG. 5D. The moving element150can be a robot arm, a sliding block and a rail, a gear and a rack, or other possible mechanisms.

As shown inFIG. 5E, the wavelength converter120is swung relative to the laser light source110front and back horizontally by the moving element150, as indicated by the arrow inFIG. 5E. The moving element150can be a robot arm. The center125of the wheel122is utilized as a pivot point, and the wheel122is swung back and forth horizontally relative to the laser light source110by the moving element150about the center125of the wheel122.

As is evident from the above description, the motor130is utilized for providing a first moving mode to the wheel122, and the moving element150is utilized for providing a second moving mode to the wavelength converter120. When the wheel122is in the first moving mode, the wheel122is rotated relative to the laser light source110by the motor130, which is connected to the center125of the wheel122. When the wavelength converter120is in the second moving mode, the wavelength converter120is moved relative to the laser light source110. Different ways in which the second moving mode may be realized are shown by way of nonlimiting examples inFIG. 5AtoFIG. 5E.

Generally speaking, the wavelength converter120can be swung relative to the laser light source110. Alternatively, assuming that a light emitting direction of the laser light source110is in a z-axis direction, the center125of the wheel122is moved at least on an x-y plane, which is perpendicular to the z axis. Any possible design excluding that in which the wavelength converter120only moves front and back (in the z-axis direction) relative to the laser light source110, and the movement cycle of the wavelength converter is not an integer multiple of the rotation cycle can be utilized for expanding the projection path of the laser light source110on the wavelength converter120.

FIG. 6is a side view of another embodiment of the light source module of the invention. The difference between this and previous embodiments is that the wavelength converter120is arranged obliquely to the laser light source110. The front surface124for receiving the light is not arranged perpendicularly to the light emitting direction of the laser light source110(i.e., the front surface124is arranged obliquely to the light emitting direction of the laser light source110). There is an acute angle0defined between the first light beam112emitted from the laser light source110and the wavelength converter120. In order to maintain the projection path of the laser light source110in the coating area of the wavelength converting layer140, the moving distance of the wavelength converter120is preferably smaller than d*sin θ, in which d represents the coating width of the wavelength converting layer140. The relative movement between the wavelength converter120and the obliquely arranged laser light source110is the same as that described with reference toFIG. 5AtoFIG. 5E.

FIG. 7is a top view of yet another embodiment of the light source module of the invention. The difference between this and previous embodiments is that the light receiving surface is the side surface126. More particularly, the wheel122of the wavelength converter120has the front surface124, the back surface126, and the side surface128connecting the front surface124and the back surface126. The motor130is connected to the back surface126, and the wavelength converting layer140is coated on the side surface128of the wheel122. The axis of the motor130is vertical to the light emitting direction of the laser light source110. The first light beam112provided by the laser light source110is emitted onto the wavelength converting layer140coated on the side surface128of the wheel122. Hence, in this embodiment, the side surface128is the light receiving surface of the wheel122.

The wavelength converter120in this embodiment is a reflective type wavelength converter. A splitter190is disposed between the laser light source110and the wavelength converter120. The first light beam112provided by the laser light source110passes through the splitter190and emits onto the side surface128of the wavelength converter120. The first light beam112having the first wavelength is emitted onto the wavelength converting layer140and becomes a second light beam114having a second wavelength. The second light beam114is reflected by the wheel122and is then emitted onto the splitter190. The second light beam114is reflected to an imaging unit by the splitter190. Lens groups192can be disposed between the laser light source110and the wavelength converter120for adjusting the light paths of the first light beam112and the second light beam114.

In this embodiment, if the wavelength converter120is only moved relative to the laser light source110back and forth or up and down, the projection path of the first light beam112cannot be expanded. Therefore, in the light source module100using the reflective type wavelength converter120, the wavelength converter120is moved at least left and right relative to the laser light source110in order to expand the projection path of the first light beam112on the wavelength converting layer140. Similarly, in order to maintain the projection path of the laser light source110on the wavelength converter120in the coating area of the wavelength converting layer140, the lateral moving distance of the wavelength converter120must be smaller than the coating width of the wavelength converting layer140.

FIG. 8is a schematic diagram of an embodiment of a projector using the light source module of the invention. The light source module100described in any one of the previous embodiments can be utilized in a projector. The light source module100includes the laser light source110and the optical excitation device. The wavelength converter120in this embodiment is a transmission type wavelength converter. The first light beam112having the first wavelength provided by the laser light source110passes through the wavelength converting layer140on the wavelength converter120and becomes the second light beam114having the second wavelength. The second light beam114is further reflected toward an imaging unit170by a prism160for subsequent processing by the imaging unit170. The second light beam114can be a primary light or a mixed light. The second wavelength of the second light beam114is determined according to a composition of the wavelength converting material of the wavelength converting layer140. The second light beam114having the second wavelength is reflected by the prism160and enters the imaging unit170. The imaging unit170processes the second light beam114and provides an image. The light of the image is sent to a projecting unit180which projects the light of the image onto a screen. The laser light source110is disposed at a fixed position for emitting the first light beam112along a predetermined direction. As a result, the light paths of the first light beam112and the second light beam114are fixed, and the prism160, the imaging unit170and the projecting unit180can be arranged without the use of special circuit designs.

In the light source module100, the wavelength converter120is moved relative to the laser light source110, thereby expanding the projection path of the laser light source110on the wavelength converting layer140. As a result, the reaction area between the first light beam112provided by the laser light source110and the wavelength converting layer140can be enlarged, and the energy carried by the first light beam112provided by the laser light source110can be distributed on the wheel122equally to thereby increase the thermal dissipating efficiency of the wavelength converter120. Hence, a situation in which the wavelength converting layer140is damaged due to high temperatures can be prevented.

According to above embodiments, the projection path of the laser light source on the wavelength converter can be expanded by moving the wavelength converter relative to the laser light source. As a result, the reaction area between the laser light source and the wavelength converter can be enlarged, and the wavelength converting layer can be utilized more efficiently. Moreover, the energy carried by the laser light beam can be distributed on the wavelength converter more equally, thereby increasing the thermal dissipating efficiency of the wavelength converter, and preventing a situation in which the wavelength converting layer is damaged due to high temperatures.