Projection apparatus and method for adjusting a driving voltage of the projection apparatus

A projection apparatus and a method for adjusting a driving voltage of the projection apparatus are provided. The projection apparatus comprises an illuminant module, an output voltage control module, an illuminant driver module, and an illuminant driver management module. The output voltage control module is configured to output a driving voltage. The illuminant driver module is configured to output an illuminant voltage to the illuminant module after receiving the driving voltage. The illuminant driver management module is configured to receive the illuminant voltage and to detect a variation in the illuminant voltage. Then, the illuminant driver management module outputs a control signal to the output voltage control module according to the variation of the illuminant voltage. Finally, the output voltage control module adjusts the driving voltage according to the control signal.

This application claims the benefit of priority based on Taiwan Patent Application No 098123211, filed on Jul. 9, 2009, the contents of which are incorporated herein by reference in their entirety.

CROSS-REFERENCES TO RELATED APPLICATIONS

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a projection apparatus. More particularly, the present invention relates to a projection apparatus that can control a temperature by adjusting a driving voltage and reducing a volume of a heat dissipation system thereof.

2. Descriptions of the Related Art

Because of the gradual improvement of image quality, decrease in the production cost and miniaturization of projection apparatuses over recent years, the usage of projection apparatuses has increased gradually. For example, enterprise users usually present using projection apparatuses, while average individuals/homes have used projection apparatuses in home theaters. A common projection apparatus available in the market comprises at least an illuminant module and an imaging module, wherein the illuminant module is configured to provide a uniform and concentrated light beam to the imaging module. The imaging module is configured to perform the post-end image output by the foresaid concentrated light beam. For the illuminant module, a high-power bulb is usually used as a primary component to provide a source of light beams; unfortunately, such a bulb also acts as the primary heat source in the projection apparatus, which is especially the case for digital light processing (DLP) projection apparatuses.

After the projection apparatus has operated for a period of time, the intense heat generated by the illuminant module causes a substantial reduction in the operating efficiency of the projection apparatus, or even in the failure of the projection apparatus. Such a problem caused by the intense heat bothers not only a lot of users but also the manufacturers of the projection apparatuses. Therefore, to decrease the operating temperature of the illuminant modules, heat dissipation designs, such as cooling fans or heat pipes, usually have to be adopted for the illuminant modules by the manufacturers to prevent damage to the illuminant modules.

In addition, each projection apparatus has a power supply module, which is configured to supply a driving voltage to the illuminant module and operates within an operating voltage range. When an input voltage received by the power supply module falls outside the operating voltage range, the driving voltage will cause power dissipation and the substantial rise in temperature of the illuminant module, and consequently, the temperature of the projection apparatus will rise accordingly. To solve this problem, the manufacturers of the projection apparatuses usually enlarge the operating voltage range of the projection apparatus to prevent the power dissipation and the temperature rise of illuminant sources caused by the variation of the input voltage and the consequent damage of the projection apparatus. However, the enlargement of the operating voltage range causes a significant increase in the volume of the power supply module and adds to the difficulty in the adjustment of the driving voltage.

In view of this, it is important to provide a projection apparatus that has a compact volume and superior heat dissipation capability to decrease unnecessary power dissipation and maintain a stable operation of the projection apparatus for a prolonged service life.

SUMMARY OF THE INVENTION

An objective of the present invention is to provide a projection apparatus, which comprises an illuminant module, an output voltage control module, an illuminant driver module and an illuminant driver management module. The output voltage control module is configured to output a driving voltage. The illuminant driver module, which is electrically connected to the output voltage control module and the illuminant module, is configured to receive the driving voltage and output an illuminant voltage to the illuminant module according to the driving voltage. The illuminant driver management module, which is electrically connected to the output voltage control module, is configured to receive the illuminant voltage, detect a variation of the illuminant voltage, and output a first control signal to the output voltage control module according to the variation of the illuminant voltage such that the output voltage control module adjusts the driving voltage according to the first control signal.

Another objective of the present invention is to provide a method for adjusting a driving voltage of the projection apparatus described above. The method comprises the following steps: (a) outputting an illuminant voltage to the illuminant module according to the driving voltage; (b) detecting a variation of the illuminant voltage; (c) outputting a first control signal according to the variation of the illuminant voltage; and (d) adjusting the driving voltage according to the first control signal.

According to the above description, by using the illuminant driver management module to adjust the driving voltage, the projection apparatus and method for adjusting the driving voltage of the projection apparatus according to the present invention can control the power dissipation and temperature of the illuminant driver module and the illuminant module of the projection apparatus while still reducing the volume thereof. As a result, the projection apparatus can be made compact, and unnecessary power dissipation is decreased to prolong the service life of the projection apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In the following description, this invention will be explained with reference to embodiments thereof. However, the description of these embodiments is only for purposes of illustration rather than limitation. It should be appreciated that in the following embodiments and attached drawings, elements unrelated to this invention are omitted from depictions; and dimensional relationships among individual elements in the attached drawings are illustrated only for ease of understanding, but not to limit the actual scale.

FIG. 1illustrates the first embodiment of the present invention which is a projection apparatus1, and it comprises an output voltage control module11, an illuminant driver module13, an illuminant module15and an illuminant driver management module19. The illuminant driver module13is electrically connected to the output voltage control module11and the illuminant module15. The illuminant driver management module19is electrically connected to the output voltage control module11and the illuminant driver module13.

When the projection apparatus1is powered on and operated, the output voltage control module11receives an input voltage121and outputs a driving voltage125to the illuminant driver module13according to the input voltage121. The input voltage121is an alternating current (AC) power source, a voltage value of which tends to vary with the place or time at which the power source is used in practical application. After receiving the driving voltage125, the illuminant driver module13outputs an illuminant voltage127and an illuminant current129to the illuminant module15. Then, in response to the illuminant voltage127and the illuminant current129, light is projected by a high-power bulb of the illuminant module15. Generally speaking, the high-power bulb of the illuminant module15is usually a high intensity discharge (HID) light tube. Thereby, the illuminant module15can provide a uniform and concentrated light beam to an imaging module of the projection apparatus1so that the imaging module outputs an image from its back-end by the aforesaid light beam.

More specifically, the output voltage control module11further comprises a voltage transformation circuit111, a power factor correction (PFC) controller113and a PFC voltage dividing feedback circuit115. The PFC controller113is electrically connected to the voltage transformation circuit111. The PFC voltage dividing feedback circuit115is also electrically connected to the voltage transformation circuit111. The PFC voltage dividing feedback circuit115further comprises a first resistor R1and a second resistor R2. The first resistor R1has a first end R1aand a second end R1b, while the second resistor R2also has a first end R2aand a second end R2b. The first end R1aof the first resistor R1is electrically connected to the voltage transformation circuit111; the second end R1bof the first resistor R1is electrically connected to the first end R2aof the second resistor R2; and the second end R2bof the second resistor R2is electrically connected to a reference potential V0. It should be noted that because the second end R1bof the first resistor R1and the first end R2aof the second resistor R2are electrically connected to present the same potential, the PFC controller113may be electrically connected to either the second end R1bof the first resistor R1or the first end R2aof the second resistor R2.

The illuminant driver management module19is electrically connected to the PFC voltage dividing feedback circuit115of the output voltage control module11. When the projection apparatus1is operating, the illuminant driver management module19receives both the illuminant voltage127and the illuminant current129, detects variations of the illuminant voltage127and the illuminant current129, and outputs a first control signal101to the PFC voltage dividing feedback circuit115according to the variations of the illuminant voltage127and the illuminant current129.

Furthermore, when a decrease in the illuminant voltage127is detected by the illuminant driver management module19, the illuminant driver management module19will output the first control signal101to the output voltage control module11accordingly. It should be particularly noted that when the illuminant driver management module19outputs the first control signal101to the PFC voltage dividing feedback circuit115of the output voltage control module11, the first control signal101will be guided to the PFC voltage dividing feedback circuit115via a third resistor R3as shown inFIG. 2and then further transmitted to the PFC controller113from the PFC voltage dividing feedback circuit115. However, the present invention has no limitation on how the first control signal101is outputted to the PFC voltage dividing feedback circuit115, and those skilled in the art may have the first control signal101guided to the PFC voltage dividing feedback circuit115in different ways depending on the practical needs; thus, this will not be further described herein.

After the first control signal101is received by the PFC voltage dividing feedback circuit115of the output voltage control module11, the first control signal101is transmitted by the PFC voltage dividing feedback circuit115to the PFC controller113via the second end R1bof the first resistor R1or the first end R2aof the second resistor R2. In response to the first control signal101, the PFC controller113will adjust the ratio of resistance values between the first resistor R1and the second resistor R2of the PFC voltage dividing feedback circuit115to output a second control signal123to the voltage transformation circuit111. Finally, the driving voltage125is adjusted by the voltage transformation circuit111according to the aforesaid ratio of resistance values and the second control signal123. For example, when the illuminant voltage127decreases, the voltage transformation circuit111decreases the driving voltage125according to the ratio of resistance values and the second control signal123. As a result, the efficiency of the illuminant driver module13is relatively improved.

Meanwhile, to prevent a high temperature caused by an increased illuminant current from the illuminant driver module13when the illuminant voltage127decreases, the projection apparatus1of this embodiment further comprises two fans17a,17band a fan control module18. More specifically, when a decrease in the illuminant voltage127is detected by the fan control module18, the fans17a,17bwill be adjusted to a higher rotational speed for enhanced heat dissipation capability. On the contrary, when an increase in the illuminant voltage127is detected by the fan control module18, the fans17a,17bwill be adjusted to a lower rotational speed to decrease the power dissipation of the projection apparatus1.

The illuminant driver management module19further detects a temperature variation of the projection apparatus1by means of a sensor (not shown), and outputs a current control signal191to the illuminant driver module13according to the temperature variation of the projection apparatus1at the same time. After receiving the current control signal191, the illuminant driver module13will adjust the illuminant current129according to the current control signal191. As a result, according to the variations of the illuminant voltage127and the illuminant current129, the electric power and temperature of the illuminant module15can be adjusted respectively by the illuminant driver management module19to maintain the luminance of the illuminant module15in an optimal range while still reducing the power dissipation and temperature of the projection apparatus1.

On the other hand, the PFC controller113is further configured to detect a variation of the first control signal101and according to the variation of the first control signal101, adjust the ratio of the resistance values between the first resistor R1and the second resistor R2to output a second control signal123to the voltage transformation circuit111so that the magnitude of the driving voltage125is adjusted by the voltage transformation circuit111according to the ratio of resistance values and the second control signal123. In the summary of the above descriptions, the illuminant driver management module19of the projection apparatus1outputs the first control signal101according to a variation of the illuminant voltage127, while the output voltage control module11adjusts the ratio of resistance values of the PFC voltage dividing feedback circuit115according to the variation of the first control signal101to output the second control signal123. Furthermore, the PFC controller113also receives the input voltage121to maintain the operation thereof. Thereby, the driving voltage125outputted by the voltage transformation circuit111can be adjusted according to the first control signal101and the illuminant voltage127to control the power dissipation and temperature of the projection apparatus1. Meanwhile, the volume of the projection apparatus1can also be reduced by maintaining the operating voltage range thereof. As a result, the projection apparatus can be made compact, and unnecessary power dissipation is decreased to prolong the service life of the projection apparatus.

It should be particularly noted that the magnitude of the driving voltage125is controlled by both the input voltage121and the first control signal101at different times. Specifically speaking, when the projection apparatus1is being powered on, the input voltage121will be received via the output voltage control module11and generate the driving voltage125. However, after the projection apparatus1has been powered on, the magnitude of the driving voltage125is adjusted by the PFC controller113according to the first control signal101. Meanwhile, the PFC controller113still receives the input voltage121to maintain the operation thereof without affecting the magnitude of the driving voltage125.

FIGS. 3,4and5illustrate the second embodiment of the present invention and the method for adjusting the driving voltage of the projection apparatus described above, which comprises the following steps. Initially in step S301, an input voltage is received by the output voltage control module. Then, in step S303, a driving voltage is outputted by the voltage transformation circuit of the output voltage control module to the illuminant driver module according to the input voltage. In step S305, an illuminant voltage and an illuminant current are outputted to the illuminant module by the illuminant driver module according to the driving voltage. In step S307, a variation of the illuminant voltage is detected by the illuminant driver management module. Subsequently, in step S309, the first control signal is outputted by the illuminant driver management module according to the variation of the illuminant voltage. In step S311, the first control signal is received by the output voltage control module, and a ratio of resistance values is adjusted by the output voltage control module according to the first control signal to output a second control signal. Finally in step S313, the driving voltage is adjusted by the voltage transformation circuit of the output voltage control module according to the second control signal and the ratio of resistance values.

More specifically, if a decrease in the illuminant voltage is detected by the illuminant driver management module in step S307, then the output voltage control module will adjust the ratio of resistance values according to the first control signal and generate a second control voltage so that the voltage transformation circuit of the output voltage control module decreases the driving voltage according to the second control signal and the ratio of resistance values.

Meanwhile, as shown inFIG. 4, the method for adjusting the driving voltage of the projection apparatus described in the second embodiment is also capable of adjusting an electric power of the illuminant module. Initially in step S401, the temperature variation of the projection apparatus is detected by the illuminant driver management module. Then, in step S403, a current control signal is outputted by the illuminant driver management module to the illuminant driver module according to the temperature variation of the projection apparatus. Finally, in step S405, the illuminant current is adjusted by the illuminant driver module according to the current control signal to adjust an electric power of the illuminant module.

It should further be noted that as shown inFIG. 5, the method for adjusting the driving voltage of the projection apparatus described in the second embodiment is also capable of controlling the rotational speed of the fans according to the illuminant voltage. Initially, in step S501, at least one fan (e.g., the fans17a,17bof the projection apparatus1in the first embodiment) is provided. Finally, in step S503, the rotational speed of the at least one fan is controlled according to the illuminant voltage. Thereby, when the illuminant voltage outputted by the illuminant driver module varies, the rotational speed of the fan(s) of the projection apparatus can be further adjusted according to the variation of the illuminant voltage to prevent unnecessary power dissipation.

In summary of the above descriptions, by using the illuminant driver management module, the PFC controller and the PFC voltage dividing feedback circuit, the driving voltage outputted by the voltage transformation circuit can be adjusted to control the power dissipation and temperature of the projection apparatus. As compared to the prior art, the present invention can prevent the illuminant driver module and the illuminant module from causing a high temperature, which may improve the operating efficiency and reduce the volume of the projection apparatus while maintaining the electric power of the illuminant module at a certain level. Thereby, an optimal light emitting efficiency is achieved and unnecessary power dissipation is decreased to prolong the service life of the projection apparatus.

The above embodiments merely give the detailed technical contents of the present invention and inventive features thereof, and are not to limit the covered range of the present invention. 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.