Patent Publication Number: US-2013235352-A1

Title: Illumination system for projection device

Description:
This application claims priority to Taiwan Patent Application No. 101107987 filed on Mar. 9, 2012. 
     CROSS-REFERENCES TO RELATED APPLICATIONS 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an illumination system for a laser projection device, and more particularly, to an illumination system that comprises a color wheel with a plurality of wave band transforming areas that is capable of automatically adjusting a position of the color wheel. 
     2. Descriptions of the Related Art 
     Nowadays, projection devices have been widely used in various situations including business meetings and home theaters. As people&#39;s demands on visual experiences have increased, the projection devices must be able to project pictures of different chrominance and brightness levels to satisfy different needs of users. 
     Among others, conventional projection devices that use lasers as light sources operate under the following principle: fluorescent powders coated on a color wheel are excited by laser rays to generate a red, blue, green or yellow light, which is then transformed by an imaging system of the projection device into a projection picture. However, the colored light excited in this way usually can only be transformed into a projection picture of a specific chrominance or a specific brightness level, but cannot be transformed into projection pictures of different chrominance or different brightness levels depending on different needs. To solve this problem, usually the original color wheel must be manually replaced by a new color wheel so that the new color wheel is excited by the laser light to generate a colored light with a different chrominance and a different brightness level from the original color wheel. However, this is both time and labor consuming It is also difficult to dispose the color wheel in precise alignment in front of the light source; moreover, this requires use of at least one additional color wheel module in the illumination system, which adds to the production cost of the projection device. 
     Accordingly, an urgent need exists in the art to provide an illumination system that can automatically generate colored lights of different chrominance and different brightness levels depending on practical needs to effectively adjust the chrominance and the brightness of the picture projected by the projection device and that can simplify the structure of the projection device to eliminate the complex adjusting procedure. 
     SUMMARY OF THE INVENTION 
     To solve the aforesaid problem, an objective of the present invention is to provide an illumination system for a projection device. The illumination system can automatically adjust a position of a color wheel thereof so that a light beam projected by a light emitting element onto the color wheel can be selectively transformed into the colored light of different chrominances and different brightness levels. Thereby, the chrominance and the brightness of the projection picture projected by the projection device can be adjusted depending on practical needs. 
     To achieve the aforesaid objective, the illumination system for a projection device of the present invention comprises a light emitting element, a color wheel and at least one actuator. The light emitting element is adapted to provide a first wave band light. The color wheel has a wheel disk, a plurality of wave band transforming areas and a rotary shaft disposed at a center of the wheel disk. The wave band transforming areas are formed on the wheel disk, and the wheel disk is adapted to rotate about the rotary shaft. The at least one actuator is connected with the color wheel to move the color wheel to a selected position so that the first wave band light is projected to one of the wave band transforming areas to excite a plurality of selected wave band lights. By adjusting the selected position of the color wheel, the first wave band light can be projected onto different wave band transforming areas depending on practical needs to generate a plurality of colored lights of different chrominance and different brightness levels. Thereby, a plurality of color scenario modes can be provided for the users&#39; choice. 
     The detailed technology and preferred embodiments implemented for the subject invention are described in the following paragraphs accompanying the appended drawings for people skilled in this field to well appreciate the features of the claimed invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a schematic view illustrating projection of a first wave band light on a first wave band transforming area in an illumination system according to an embodiment of the present invention; 
         FIG. 1B  is a schematic view illustrating projection of a second wave band light on a second wave band transforming area in an illumination system according to an embodiment of the present invention; 
         FIG. 2  is a schematic front view of a color wheel of an illumination system according to an embodiment of the present invention; 
         FIG. 3A  is a schematic view illustrating relative position relationships between a color wheel and a light emitting element in an illumination system according to an embodiment of the present invention; and 
         FIG. 3B  is a schematic view illustrating relative position relationships between a color wheel and a light emitting element in an illumination system according to another embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1A  illustrates a schematic view of an illumination system  1  for a projection device according to the present invention. The illumination system  1  comprises a light emitting element  11 , a color wheel  12  and at least one actuator  13 . In this embodiment, the light emitting element  11  is a laser diode adapted to generate a first wave band light  111 . Also, with reference to  FIG. 2 , in which a schematic front view of the color wheel  12  is illustrated, the color wheel  12  comprises a wheel disk  121 , a plurality of wave band transforming areas  122  and a rotary shaft  123  disposed at a center of the wheel disk  121 . The wave band transforming areas  122  are formed on the wheel disk  121  and, in this embodiment, may be formed by coating a plurality of fluorescent materials on the wheel disk  121 . The wheel disk  121  is adapted to rotate about the rotary shaft  123 . The at least one actuator  13  is connected with the color wheel  12  to move the color wheel  12  to a selected position in a direction y so that the first wave band light  111  is projected to one of the wave band transforming areas  122  to excite a plurality of selected wave band lights. The projection device comprises an imaging module for transforming the selected wave band lights into a projection picture (not shown). 
     It shall be appreciated that the at least one actuator of the illumination system of the present invention can be manually or electrically driven to adjust the selected position of the color wheel. Hereinbelow, only electrically driving the at least one actuator to adjust the selected position of the color wheel will be illustrated in this embodiment of the present invention. 
     With reference back to  FIG. 1 , the illumination system  1  comprises a storage module  14  and a control module  15  electrically connected with each other. The storage module  14  may have a plurality of scenario mode signals stored therein. The control module  15  is connected to the at least one actuator  13 . The control module  15  is adapted to, according to one of the scenario mode signals, drive the at least one actuator  13  to move the color wheel  12  to the selected position in the y direction so that the light  111  is projected onto one of the wave band transforming areas  122 . In this embodiment, the direction y is in a vertical direction.  FIG. 3A  illustrates a schematic view of relative positional relationships between the color wheel  12  and the light emitting element  11 . The light emitting element  11  is disposed at a position near a top portion of the color wheel  12 , and the at least one actuator  13  can drive the light emitting element  11  to move in a vertical direction so that the first wave band light  111  is projected onto one of the wave band transforming areas  122 . 
     However, as shown in  FIG. 3B , the color wheel  12  may also be moved in a horizontal direction x in other embodiments of the present invention; that is, the light emitting element  11  may be disposed near a side of the color wheel  12 . The at least one actuator  13  drives the light emitting element  11  to move in the horizontal direction x. However, the color wheel  12  is not limited to movement in the vertical direction or in the horizontal direction, but may also be moved in any other direction that allows the first wave band light  111  to be projected onto one of the wave band transforming areas  122 . 
     Now, the structure of the color wheel  12  will be detailed. As shown in  FIG. 2 , the wave band transforming areas  122  of the color wheel  12  include a first wave band transforming area  122   a  and a second wave band transforming area  122   b . The first wave band transforming area  122   a  is formed at a periphery of the color wheel  121 , while the second wave band transforming area  122   b  is formed between the rotary shaft  123  and the first wave band transforming area  122   a . In this embodiment, the first wave band transforming area  122   a  has a first red fluorescent area R 1 , a first blue fluorescent area B 1 , a first green fluorescent area G 1  and a first yellow fluorescent area Y 1 ; while the second wave band transforming area  122   b  has a second red fluorescent area R 2 , a second green fluorescent area G 2  and a second blue fluorescent area B 2 . In other embodiments of the present invention, the fluorescent areas of the wave band transforming areas  122  may be altered depending on practical needs, and the present invention has no limitation thereon; for example, the yellow fluorescent area Y 1  of the first wave band transforming area  122   a  may also be replaced by a white fluorescent area. As the wheel disk  121  rotates about the rotary shaft  123 , the first wave band light  111  can be projected onto the individual fluorescent areas of the wave band transforming areas  122  to excite lights of different wave bands respectively. The wave band lights generated when the first wave band light  111  is projected onto the first wave band transforming area  122   a  and the second wave band transforming area  122   b  with different chrominance and different brightness levels. Thus, projection pictures of different chrominance and different brightness levels can be generated by the imaging module of the projection device. The operations of this embodiment will be detailed as follows. 
     More specifically, in the illumination system  1  of the present invention, a plurality of scenario modes may be predefined to represent a plurality of color scenarios, and a plurality of corresponding scenario mode signals are predefined and stored in the storage module. For example, two scenario modes are predefined in this embodiment: a high chrominance scenario mode and a high brightness scenario mode. A first scenario mode signal  141   a  and a second scenario mode signal  141   b  are predefined corresponding to the two scenario modes respectively. In this embodiment, the first scenario mode signal  141   a  may be set as a high chrominance scenario mode signal, while the second scenario mode signal  141   b  may be set as a high brightness scenario mode signal. With reference to  FIG. 1A , when receiving the first scenario mode signal  141   a , the control module  15  drives the at least one actuator  13  to move the color wheel  12  to a first selected position A in the direction y so that the first wave band light  111  is projected onto the first wave band transforming area  122   a  to excite a plurality of first selected wave band lights. In other words, in the first scenario mode, the wave band lights described above are the first selected wave band lights that are different from the first wave band light. 
     With reference to  FIG. 1B , when receiving the second scenario mode signal  141   b , the control module  15  drives the at least one actuator  13  to move the color wheel  12  to a second position B in the y direction so that the exciting light  111  is projected onto the second wave band transforming area  122   b  to excite a plurality of second selected wave band lights. In other words, in the second scenario mode, the wave band lights described above are the second selected wave band lights that are different from the first wave band lights. 
     By adjusting the chrominance and brightness levels of the fluorescent areas of the first wave band transforming area  122   a  and the second wave band transforming area  122   b , the chrominance of the first selected wave band lights can be controlled to be higher than that of the second selected wave band lights so that a projection picture with a high chrominance is formed by the first selected wave band lights. The brightness of the second selected wave band lights can be controlled to be higher than that of the first selected wave band lights so that a projection picture with a high brightness can be formed by the second selected wave band lights. Furthermore, because the first wave band transforming area  122   a  can be excited by the exciting light  111  to emit a colored light with a high chrominance, the temperature generated therein is higher than that in the second wave band transforming area  122   b.    
     Therefore, disposing the first wave band transforming area  122   a  at the periphery of the color wheel  12  facilitates rapid dissipation of the heat energy to prevent overheating of the wheel disk  121 . 
     Apart from disposing the first wave band transforming area  122   a  and the second wave band transforming area  122   b  to provide colored lights of different chrominance and different brightness levels, other different wave band transforming areas may also be additionally formed on the color wheel in other embodiments of the present invention. For example, a third wave band transforming area (not shown) may be additionally disposed between the second wave band transforming area  122   b  and the rotary shaft  123 , and is adjusted to generate wave band lights with a chrominance and a brightness different from those of the wave band lights generated by the first wave band transforming area  122   a  and the second wave band transforming area  122   b . Furthermore, a third scenario mode signal may be further defined so that the excited light is projected onto the third wave band transforming area when the at least one actuator  13  moves the color wheel  12  to a third selected position according to the third scenario mode signal. This will be readily appreciated by those skilled in the art, and thus, will not be further described herein. 
     It shall be appreciated that the shapes and sizes of the individual elements of the illumination system of the present invention as well as the relative position relationships among the at least one actuator  13 , the storage module  14  and the control module  15  are only depicted for ease of understanding but not to limit the actual structures, ratios and positions thereof. The purpose of controlling the color wheel  12  to move and excited different colored lights can be achieved as long as the at least one actuator  13  can be manually or electrically driven to move the color wheel  12  to a selected position so that the first wave band light  111  of the light emitting element  11  is projected to one of the wave band transforming areas  122  of the color wheel  12 . 
     According to the above descriptions, as compared to illumination systems for the conventional projection devices that change the chrominance and the brightness by replacing a color wheel, the illumination system for a projection device of the present invention has only a single color wheel comprising a plurality of wave band transforming areas. By adjusting the position of the single color wheel, the band transforming areas image the light from the light emitting element into projection pictures of different chrominance and different brightness levels; this enhances the color variability of the pictures projected by the projection device, and eliminates the unnecessary elements and replacement procedures, thus, lowering the production cost of the projection device. 
     The above disclosure is related to the detailed technical contents and inventive features thereof. People skilled in this field may proceed with a variety of modifications and replacements based on the disclosures and suggestions of the invention as described without departing from the characteristics thereof. Nevertheless, although such modifications and replacements are not fully disclosed in the above descriptions, they have substantially been covered in the following claims as appended.