Patent Application
20090296005
The present invention relates to a luminance control method and a luminance control device, and more particularly to a luminance control method and a luminance control device for use with a projection system.
Recently, a digital projection and display system is commercially available from Texas Instruments Incorporated (TI) under the trademark Digital Light Processing® (also referred as DLP). The DLP digital projection and display system utilizes a digital micromirror device (DMD) in its optical path. The digital micromirror device (DMD) is fabricated according to a MEMS (Micro-Electro-Mechanical System) technology. Typically, the DMD includes a great amount of tiny digital light switches. The digital light switches are very small-sized micromirrors allowing for fast and precise rotation in receipt of electronic control signals. Each micromirror is a light switch that is capable of reflecting light in one of two directions. When the micromirror is in an “on” state, the incident light is reflected into the pupil of the projection lens and thus the micromirror appears bright in this “on” state. Whereas, when the micromirror is in an “off” state, the incident light is reflected out of the pupil of the projection lens and thus the micromirror appears dark in this “off” state.
Desired gray scales are achieved by using binary pulsewidth modulation to control the micromirrors. For example, a digital data of an 8-bit binary code may be converted into a pulse width of 256 discrete levels such that there are 256 bright-to-dark duration ratios for the micromirror. That is, this grayscale sets an image resolution of 256.
Furthermore, the fractions of the color sections of the color wheel 13 have great influences on characteristics of the resulting color. That is, by designing different fractions of the color sections to make an angular allocation in a revolution (e.g. 360°) of the color wheel 13, a desired color is achieved. If only one parameter (e.g. the angular allocation) is utilized, the adjustable light colors are usually insufficient to comply with various scenarios. In addition, the angular allocation of the color wheel 13 usually fails to be modified and thus the flexibility of designing the color wheel is restricted.
Therefore, there is a need of providing a luminance control method and a luminance control device to obviate the drawbacks encountered from the prior art.
In accordance with an embodiment of the present invention, there is provided a luminance control method for use with a projection system having a light source and a color wheel. The luminance control method includes steps of issuing a power control signal to define a plurality of time segments in a cycle period, wherein luminance messages composed of different numbers of pulses are included in respective time segments; reading out the luminance messages included in the respective time segments in receipt of the power control signal; and adjusting luminance values of the light emitted by the light source to be projected to the color wheel according to the luminance messages.
In accordance with another embodiment of the present invention, there is provided a luminance control device for use with a projection system having a light source and a color wheel. The luminance control device includes a processing module, a power supply unit and a lamp driver. The processing module issues a power control signal to define a plurality of time segments in a cycle period, wherein luminance messages composed of different numbers of pulses are included in respective time segments. The power supply unit is used for powering the light source. The lamp driver is electrically connected to the processing module and the power supply unit for reading out the luminance messages included in the respective time segments in receipt of the power control signal. The power levels to be outputted from the lamp driver to the light source are adjusted according to the luminance messages, thereby adjusting luminance values of the light emitted by the light source to be projected to the color wheel.
The luminance control method and the luminance control device of the embodiments of the present invention are capable of achieving various light colors in different scenarios by using a power control signal containing different numbers of pulses and different color sections of a color wheel.
Other objectives, features and advantages of the present invention will be further understood from the further technological features disclosed by the embodiments of the present invention wherein there are shown and described preferred embodiments of this invention, simply by way of illustration of modes best suited to carry out the invention.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration specific embodiments in which the invention may be practiced. In this regard, directional terminology, such as “top,” “bottom,” “front,” “back,” etc., is used with reference to the orientation of the Figure(s) being described. The components of the present invention can be located in a number of different orientations. As such, the directional terminology is used for purposes of illustration and is in no way limiting. On the other hand, the drawings are only schematic and the sizes of components may be exaggerated for clarity. It is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present invention. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless limited otherwise, the terms “connected,” “coupled,” and “mounted” and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings. Similarly, the terms “facing,” “faces” and variations thereof herein are used broadly and encompass direct and indirect facing, and “adjacent to” and variations thereof herein are used broadly and encompass directly and indirectly “adjacent to”. Therefore, the description of “A” component facing “B” component herein may contain the situations that “A” component directly faces “B” component directly or one or more additional components are between “A” component and “B” component. Also, the description of “A” component “adjacent to” “B” component herein may contain the situations that “A” component is directly “adjacent to” “B” component or one or more additional components are between “A” component and “B” component. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive.
For obviating the drawbacks encountered from the prior art, the luminance control device of the present invention may adjust the power levels of a light source inside a projection system according to a power control signal. Consequently, the light emitted by the light source has different intensities in different time segments.
Take a color wheel having four color sections of white color (W), red color (R), green color (G) and blue color (B) for example. Each of the W, R, G and B sections has a fan-shaped area whose inner angle is 90 degree in relation to the rotation axis. It is certainly that the inner angles may be varied according to the manufacturer's design. In a case that four time segments are defined in one cycle period, the duration of each time segment is equal to one-fourth of the cycle period. In accordance with a key feature of the present invention, the numbers of pulses contained in the time interval T0 at the tail portion of a current time segment define the power level to be outputted by the lamp driver in the next time segment. As a result, the lamp driver is controlled to output the corresponding power level in the next time segment so as to adjust the light intensities in different time segments. In the other embodiments, the number of time segments is less than the number of color sections of the color wheel. Under this circumstance, the light intensities of different colors may be identical.
Hereinafter, a luminance control method for use with a projection system according to a preferred embodiment of the present invention will be illustrated with reference to a flowchart of
From the above description, the luminance control method and the luminance control device of the present invention are capable of achieving various light colors in different scenarios by using a power control signal containing different numbers of pulses and a color wheel with different color sections. As a consequence, the designing flexibility is enhanced and the drawbacks encountered from the prior art are obviated.
The foregoing description of the preferred embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form or to exemplary embodiments disclosed. Accordingly, the foregoing description should be regarded as illustrative rather than restrictive. Obviously, many modifications and variations will be apparent to practitioners skilled in this art. The embodiments are chosen and described in order to best explain the principles of the invention and its best mode practical application, thereby to enable persons skilled in the art to understand the invention for various embodiments and with various modifications as are suited to the particular use or implementation contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents in which all terms are meant in their broadest reasonable sense unless otherwise indicated. Therefore, the term “the invention”, “the present invention” or the like does not necessarily limit the claim scope to a specific embodiment, and the reference to particularly preferred exemplary embodiments of the invention does not imply a limitation on the invention, and no such limitation is to be inferred. The invention is limited only by the spirit and scope of the appended claims. The abstract of the disclosure is provided to comply with the rules requiring an abstract, which will allow a searcher to quickly ascertain the subject matter of the technical disclosure of any patent issued from this disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Any advantages and benefits described may not apply to all embodiments of the invention. It should be appreciated that variations may be made in the embodiments described by persons skilled in the art without departing from the scope of the present invention as defined by the following claims. Moreover, no element and component in the present disclosure is intended to be dedicated to the public regardless of whether the element or component is explicitly recited in the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 097120478 | Jun 2008 | TW | national |
