Projection device and driving circuit module thereof

Abstract

A projection device and a driving circuit module thereof. A power supply unit provides a driving voltage to an output terminal thereof. A bypass circuit is coupled between the output terminal and a ground terminal of the power supply unit. When the power supply unit stops providing the driving voltage, the bypass circuit provides a discharging path for discharging the power of an output capacitor and storing part of the power from the output capacitor, so as to reduce the voltage value of the output terminal of the power supply unit to a first voltage value. The first voltage value is lower than a minimum operating voltage value. The projection device and the driving circuit module thereof provided by the present application can optimize the starting and closing time of a light source unit of the projection device, and improve the display quality of the projection device.

Description

Technical Field

[0001] This invention relates to a display device, and more particularly to a projection device and its driving circuit module. Background Technology

[0002] In a typical projection device, the output of the light source driver circuit includes an output inductor and an output capacitor. One end of the output capacitor is connected to the output terminal, and the other end is grounded to store, release, and filter energy, thereby providing a stable output voltage to the light source element. Since the inductor and capacitor are energy storage components, even when the light source driver circuit is turned off, their residual energy will still be sent to the light source until the energy is exhausted. This results in an excessive delay between the actual shutdown time of the light source element and the shutdown time of the light source driver circuit, preventing the light source element from shutting off in time. This can easily cause abnormal colors in the projected image.

[0003] The "Background Art" paragraph is only used to help understand the content of this invention. Therefore, the content disclosed in the "Background Art" paragraph may include some known technologies that are not known to those skilled in the art. The content disclosed in the "Background Art" paragraph does not represent the problems to be solved by such content or one or more embodiments of this invention, nor does it represent that it was known or recognized by those skilled in the art prior to this application. Summary of the Invention

[0004] This invention provides a projection device and its driving circuit module, which can optimize the start-up and shutdown time of the light source unit of the projection device and improve the display quality of the projection device.

[0005] Other objects and advantages of the present invention can be further understood from the technical features disclosed herein.

[0006] To achieve one, some, or all of the above objectives, or other objectives, the driving circuit module of the present invention is used to drive a light source unit having a minimum operating voltage value. The driving circuit module includes a power supply unit and a bypass circuit. The power supply unit has an output terminal and a ground terminal, and includes an output capacitor coupled between the output terminal and the ground terminal of the power supply unit. The output terminal of the power supply unit is coupled to the light source unit, and the power supply unit provides a driving voltage to the output terminal. The bypass circuit is coupled between the output terminal and the ground terminal of the power supply unit. In response to the power supply unit stopping the supply of the driving voltage, the bypass circuit provides a discharge path for the output capacitor to discharge and store a portion of the energy from the output capacitor, causing the voltage value at the output terminal of the power supply unit to decrease to a first voltage value. The first voltage value is lower than the minimum operating voltage value.

[0007] The present invention also provides a projection device, comprising an illumination system, a light valve, and a projection lens. The illumination system provides an illumination beam and includes a light source unit and a drive circuit module. The drive circuit module drives the light source unit to provide at least one illumination beam, the illumination beam including the aforementioned at least one beam, and the light source unit having a minimum operating voltage value. The drive circuit module includes a power supply unit and a bypass circuit. The power supply unit has an output terminal and a ground terminal, and includes an output capacitor coupled between the output terminal and the ground terminal. The output terminal of the power supply unit is coupled to the light source unit, and the power supply unit provides a drive voltage to the output terminal. The bypass circuit is coupled between the output terminal and the ground terminal of the power supply unit. In response to the power supply unit ceasing to provide the drive voltage, the bypass circuit provides a discharge path for the output capacitor to discharge and store a portion of the energy from the output capacitor, causing the voltage value at the output terminal of the power supply unit to decrease to a first voltage value. The first voltage value is lower than the minimum operating voltage value. The light valve is disposed on the transmission path of the illumination beam to convert the illumination beam into an image beam. The projection lens is positioned in the path of the image beam to project the image beam out of the projection device.

[0008] Based on the above, the bypass circuit of this embodiment of the invention responds when the power supply unit stops providing the driving voltage, provides a discharge path for the output capacitor to discharge and store part of the energy from the output capacitor, thereby reducing the voltage value at the output terminal to a value lower than the minimum operating voltage value of the light source unit. In this way, when the power supply unit stops providing the driving voltage, the output voltage of the drive circuit module can be quickly adjusted to an appropriate voltage, optimizing the start-up and shutdown time of the light source unit of the projection device and improving the display quality of the projection device.

[0009] To make the above features and advantages of the present invention more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings. Attached Figure Description

[0010] Figure 1 This is a block diagram of a projection device according to an embodiment of the present invention.

[0011] Figure 2 and Figure 3 This is a schematic diagram of the driving circuit module and the light source unit in a lighting system according to an embodiment of the present invention.

[0012] Figure 4A This is a schematic diagram of the circuit operation state of a drive circuit module according to an embodiment of the present invention.

[0013] Figure 4B This is a waveform diagram of the switching action, output voltage, and output current of the drive circuit module according to an embodiment of the present invention.

[0014] Figure 5A This is another circuit operation state of the drive circuit module according to an embodiment of the present invention.

[0015] Figure 5B This is a waveform diagram of another switching action, output voltage, and output current of the drive circuit module according to an embodiment of the present invention. Detailed Implementation

[0016] The foregoing description and other technical contents, features, and effects of this invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the accompanying drawings. The directional terms mentioned in the following embodiments, such as up, down, left, right, front, or back, are only for reference to the directions in the drawings. Therefore, the directional terms used are for illustrative purposes and not for limiting the invention. Furthermore, the term "coupled" mentioned in the following embodiments can refer to any direct or indirect connection means. In addition, the term "signal" can refer to at least one current, voltage, charge, temperature, data, electromagnetic wave, or any other one or more signals.

[0017] Please refer to Figure 1 , Figure 1 This is a block diagram of a projection device according to an embodiment of the present invention. The projection device 100 includes an illumination system 102, a light valve 104, and a projection lens 106. The illumination system 102 provides an illumination beam IL. The light valve 104 is disposed in the transmission path of the illumination beam IL, converting the illumination beam IL into an image beam IIL. The projection lens 106 is disposed in the transmission path of the image beam IIL, for projecting the image beam IIL out of the projection device 100. Further, the illumination system 102 includes a drive circuit module 108 and a light source unit 110, the drive circuit module 108 being coupled to the light source unit 110. The drive circuit module 108 can drive the light source unit 110 to provide at least one beam OL, the illumination beam IL including the at least one beam OL provided by the light source unit 110. The light source unit 110 includes one or more light-emitting elements, each of which is, for example, a light-emitting diode (LED) element or a laser diode (LD) element or a combination thereof. If the light source unit 110 includes multiple light-emitting elements, these light-emitting elements can be configured into an array.

[0018] In detail, such as Figure 2As shown, the driving circuit module 108 in the lighting system 102 includes a power supply unit 202 and a bypass circuit 204. The power supply unit 202 has an output terminal N1 and a ground terminal GND. The output terminal N1 of the power supply unit 202 is coupled to the load connection terminal N2 of the driving circuit module 108. The bypass circuit 204 is coupled between the output terminal N1 of the power supply unit 202 and the ground terminal GND. The power supply unit 202 can provide a driving voltage to drive the light source unit 110 to provide at least one light beam OL at the load connection terminal N2. In this embodiment, the lighting system 102 also includes an optical component 112 for adjusting the at least one light beam OL from the light source unit 110 to form an illumination beam IL. The optical component 112 includes at least one or a combination of a lens, a reflective element, a beam splitter, a beam combiner, a beam homogenizer, a wavelength conversion element, a phase modulation element, and a polarization element. The accompanying drawings and this description use a light source unit 110 containing one light-emitting element as an example. The circuit and operating principle of a light source unit 110 containing multiple light-emitting elements are the same as those of a single light-emitting element, so they will not be described again here.

[0019] In this embodiment, the power supply unit 202 includes a front-end circuit 206 and a back-end circuit formed by at least an output inductor L1 and an output capacitor C1. The power supply unit 202 is, for example, at least one or a combination of a DC / DC converter and an AC / DC converter, such as a buck converter, a boost converter, a buck-boost converter, a flyback converter, an LLC converter, etc., but is not limited thereto. The output inductor L1 of the power supply unit 202 is coupled between the front-end circuit 206 and the output terminal N1 of the power supply unit 202, and the output capacitor C1 is coupled between the output terminal N1 of the power supply unit 202 and the ground terminal GND. The front-end circuit 206 provides a DC driving voltage to the light source unit 110 through the output inductor L1 and the output capacitor C1.

[0020] When the power supply unit 202 stops providing the driving voltage, the bypass circuit 204 provides a discharge path for the output capacitor C1 to discharge and store part of the electrical energy from the output capacitor C1, causing the voltage Vout at the output terminal N1 or the load connection terminal N2 to quickly decrease to a first voltage value that is lower than the minimum operating voltage value of the light source unit 110 but greater than zero. Taking the light source unit 110 as a single light-emitting diode (LED) as an example, the minimum operating voltage value of the light source unit 110 can be, for example, the forward voltage value of the LED. Alternatively, if the light source unit 110 contains a series array of N LEDs, the minimum operating voltage value is N times the forward voltage value of the LED.

[0021] Furthermore, when the power supply unit 202 starts to operate and provides the drive voltage, the bypass circuit 204 can cut off the discharge path. In this way, the drive voltage provided by the power supply unit 202 will start to charge the output capacitor C1 and provide it to the output terminal N1, causing the voltage value Vout of the output terminal N1 to rise to a second voltage value that is greater than or equal to the minimum operating voltage value of the light source unit 110, wherein the second voltage value is greater than or equal to the minimum operating voltage value of the light source unit 110.

[0022] In short, when the power supply unit 202 stops providing the driving voltage, it quickly lowers the voltage value Vout at the output terminal N1, thus shortening the time for the light source unit 110 to be turned off. Furthermore, the bypass circuit 204, by storing some electrical energy, prevents the voltage value Vout at the output terminal N1 from being directly pulled down to zero, thereby shortening the time required to re-turn on the light source unit 110. Therefore, the startup and shutdown times of the light source unit 110 of the projection device 100 can be effectively optimized, improving the display quality of the projection device 100. It should be noted that the "shutdown time" mentioned in this description refers to the time difference between when the power supply unit 202 stops providing the driving voltage and when the light source unit 110 is actually turned off, while the "startup time" refers to the time difference between when the power supply unit 202 starts providing the driving voltage and when the light source unit 110 is actually started.

[0023] Please see Figure 3 In one embodiment of the present invention, the drive circuit module 108 further includes a control unit 302, and the bypass circuit 204 includes a bypass capacitor C2, a bypass resistor R1, and a bypass switch SW1. The control unit 302 is coupled to the enable terminal EN of the front-end circuit 206 located in the power supply unit 202, and is further coupled to the bypass switch SW1 of the bypass circuit 204 to transmit a control signal. The control signal corresponds to the enable signal. The control unit 302 enables or disables the operation of the front-end circuit 206 by outputting the enable signal to the enable terminal EN of the front-end circuit 206. The bypass capacitor C2 and the bypass resistor R1 are connected in parallel, and connected in series with the bypass switch SW1 between the output terminal N1 of the power supply unit 202 and the ground terminal GND. In some embodiments, the parallel bypass capacitor C2 and bypass resistor R1 in the bypass circuit 204 can be interchanged with the bypass switch SW1, instead of... Figure 3 Examples are limited to these.

[0024] Please see Figure 4A and Figure 4BAs shown, when the enable signal provided by the control unit 302 is to control the front-end circuit 206 to stop working, the control unit 302 simultaneously provides a control signal to the bypass switch SW1 according to the enable signal to control the bypass switch SW1 to be turned on (ON), for example, controlling the bypass switch SW1 to be turned on at the same time as or after the enable signal is switched to the off signal. When the bypass switch SW1 is turned on, the output capacitor C1 and the bypass capacitor C2 form a parallel circuit. The energy of the output capacitor C1 is distributed to the bypass capacitor C2, so that the bypass capacitor C2 stores part of the energy released by the output capacitor C1, and the voltage value Vout of the output terminal N1 is reduced to below the minimum operating voltage value during the off time t_off. The capacitance value of the bypass capacitor C2 should meet the following condition (1).

[0025]

[0026] Where Vo is the rated output voltage value of the power supply unit 202, V TH This is the minimum operating voltage value for the light source unit 110.

[0027] The voltage value at the output terminal N1 after the bypass switch SW1 is turned on and the output capacitor C1 and bypass capacitor C2 have completed the power distribution. In other words, condition (1) ensures that after the bypass switch SW1 is turned on, the voltage value Vout at the output terminal N1 can be quickly pulled down to a value lower than the minimum operating voltage value of the light source unit 110.

[0028] For example, in the first design case of the drive circuit module 108, the rated output voltage Vo of the power supply unit 202 is 5V, and the minimum operating voltage V of the light source unit 110 is... TH The voltage is 3.5V. According to condition (1), the capacitance value of the bypass capacitor C2 should be less than 7 / 3 of the capacitance value of the output capacitor C1 to achieve the purpose of turning off the light source unit 110. In this example, the capacitance values ​​of the output capacitor C1 and the bypass capacitor C2 are taken to be equal, that is, C1 = C2. After the bypass switch SW1 is turned on, the voltage value Vout of the output terminal N1 is reduced from the voltage value Va (for example, the rated output voltage value Vo = 5V) to the first voltage value. The first voltage value V1 is lower than the minimum operating voltage value V. TH =3.5V, the output current Iout supplied to the light source unit 110 drops from the current value I1 to zero, and the light source unit 110 switches to the off state.

[0029] Please see Figure 5A and 5BAs shown, further, when the enable signal provided by the control unit 302 is to control the front-end circuit 206 to start working, the control unit 302 provides a control signal to the bypass switch SW1 according to the enable signal to control the bypass switch SW1 to open (OFF) and cut off the discharge path. For example, the bypass switch SW1 is opened at the same time or after the enable signal is switched to the start signal. The front-end circuit 206 supplies power to the output terminal N1 and charges the output capacitor C1 through the output inductor L1 and the output capacitor C1. The voltage value Vout of the output terminal N1 rises from the voltage value Vb to the second voltage value V2. The voltage value Vout of the output terminal N1 rises to a value greater than or equal to the minimum operating voltage V of the light source unit 110 within the start-up time t_on. TH The light source unit 110 is activated. At the same time, the bypass resistor R1 discharges the bypass capacitor C1, depleting the energy stored in the bypass capacitor C1, so that when the bypass switch SW1 is turned on again, some of the energy stored in the output capacitor C1 can be supplied.

[0030] When the front-end circuit 206 stops working, the voltage value Vout at the output terminal N1 is pulled down to below the minimum operating voltage value V. TH The first voltage value V1 is not pulled down to zero, so when the light source unit 110 is turned on again, it is not necessary to start from zero and raise the voltage value Vout of the output terminal N1 to a value greater than or equal to the minimum operating voltage value V. TH The second voltage value V2 is used to start the light source unit 110 and provide an output current Iout with a current value I1, which quickly switches the light source unit 110 to the working state of providing an illumination beam IL, thus effectively reducing the start-up time of the light source unit 110.

[0031] The resistance value of the bypass resistor R1 determines the discharge time of the bypass capacitor C2. Since the bypass capacitor C2 should complete its discharge within the off interval Toff of the light source unit 110, the discharge time of the bypass capacitor C2 to the bypass resistor R1 should at least meet the following formula (2).

[0032] Toff=5R1×C2 (2)

[0033] For example, in the second design case of the drive circuit module, the set switching frequency of the light source unit 110 is set to 120Hz, and the duty cycle is 33%. Therefore, the off interval duration Toff of the light source unit 110 is... Assuming C1 = 4.7uF and C2 = 2.2uF, the bypass resistor R1 should be... Therefore, the bypass resistor R1 can be set to 510 ohms.

[0034] The values ​​of the output capacitor C1, bypass capacitor C2, and bypass resistor R1 described above are merely exemplary embodiments. The values ​​of these components can be adjusted according to actual needs and are not limited to the above embodiments. For example, the capacitance values ​​of the output capacitor C1 and bypass capacitor C2 can be based on the minimum operating voltage value V. TH To make adjustments, the energy distribution between output capacitor C1 and bypass capacitor C2 is adjusted by changing their capacitance values, thereby lowering the output voltage Vout to below the minimum operating voltage V. TH However, the voltage value is greater than zero.

[0035] In summary, the bypass circuit 204 of the drive circuit module 108 of the present invention responds to the power supply unit 108 stopping the supply of drive voltage, provides a discharge path for the output capacitor C1 to discharge and store part of the energy from the output capacitor C1, thereby causing the voltage value of the output terminal N1 to drop rapidly to below the minimum operating voltage value of the light source unit 110, thus immediately turning off the light source unit 110; furthermore, when the power supply unit 108 starts to supply drive voltage, it can also shorten the time for the voltage of the output terminal N1 to rise to above the minimum operating voltage value by avoiding dropping the voltage of the output terminal N1 to zero voltage, thereby immediately starting the light source unit 110, achieving the purpose of optimizing the turn-on and turn-off time of the light source unit of the projection device, and improving the display quality of the projection device.

[0036] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Any simple equivalent changes and modifications made in accordance with the claims and description of the invention are still within the scope of this patent. Furthermore, no embodiment or claim of the present invention needs to achieve all the objectives, advantages, or features disclosed in the invention. In addition, the abstract and title (invention title) are only used to assist in patent document retrieval and are not intended to limit the scope of the invention. Moreover, the terms "first," "second," etc., mentioned in the specification are only used to indicate the names of elements and are not used to limit the upper or lower limit of the number of elements.

Claims

1. A driving circuit module for driving a light source unit, the light source unit having a minimum operating voltage value, characterized in that, The drive circuit module includes a power supply unit and a bypass circuit, wherein: The power supply unit has an output terminal and a ground terminal, and includes an output capacitor coupled between the output terminal and the ground terminal. The output terminal is coupled to the light source unit, and the power supply unit is used to provide a driving voltage to the output terminal; and The bypass circuit is coupled between the output terminal and the ground terminal; The power supply unit stops providing the driving voltage, and the bypass circuit provides a discharge path for the output capacitor to discharge and store part of the energy from the output capacitor, so that the voltage value at the output terminal is reduced to a first voltage value. The first voltage value is lower than the minimum operating voltage value.

2. The driving circuit module according to claim 1, characterized in that, The first voltage value is greater than zero; When the power supply unit starts to provide the driving voltage, the bypass circuit stops providing the discharge path, and the driving voltage of the power supply unit charges the output capacitor, causing the voltage value at the output terminal to rise to the second voltage value. The second voltage value is greater than or equal to the minimum operating voltage value.

3. The driving circuit module according to claim 1 or 2, characterized in that, The bypass circuit includes a bypass capacitor, a bypass resistor, and a bypass switch, wherein: The bypass capacitor is connected in parallel with the bypass resistor, and is connected in series with the bypass switch between the output terminal and the ground terminal.

4. The driving circuit module according to claim 3, characterized in that, When the power supply unit stops providing the driving voltage, the bypass switch is turned on to form the discharge path, and the bypass capacitor discharges the output capacitor and stores part of the electrical energy from the output capacitor; In response to the power supply unit starting to provide the drive voltage, the bypass switch opens to cut off the discharge path, and the bypass resistor discharges the bypass capacitor.

5. The driving circuit module according to claim 3, characterized in that, The capacitance value C2 of the bypass capacitor meets the following requirements: Where C1 is the capacitance value of the output capacitor, Vo is the rated output voltage value of the power supply unit, and V TH This refers to the lowest operating voltage value of the light source unit.

6. The driving circuit module according to claim 3, characterized in that, The drive circuit module includes a control unit, wherein: The control unit is coupled to the power supply unit and the bypass switch, wherein the control unit controls the conduction state of the bypass switch according to the enable signal provided to the power supply unit.

7. The driving circuit module according to claim 6, characterized in that, The enable signal provided by the control unit is to either stop the power supply unit from providing the drive voltage or to start the power supply unit from providing the drive voltage.

8. A projection device, characterized in that, The projection device includes an illumination system, a light valve, and a projection lens, wherein: The lighting system is used to provide an illumination beam, wherein the lighting system includes a light source unit and a driving circuit module, the driving circuit module being used to drive the light source unit to provide at least one illumination beam, the illumination beam including the at least one beam, the light source unit having a minimum operating voltage value; the driving circuit module includes a power supply unit and a bypass circuit, wherein: The power supply unit has an output terminal and a ground terminal, and includes an output capacitor coupled between the output terminal and the ground terminal. The output terminal is coupled to the light source unit, and the power supply unit is used to provide a driving voltage to the output terminal; and The bypass circuit is coupled between the output terminal and the ground terminal; When the power supply unit stops providing the driving voltage, the bypass circuit provides a discharge path for the output capacitor to discharge and store part of the energy from the output capacitor, thereby reducing the voltage value at the output terminal to a first voltage value. The first voltage value is lower than the minimum operating voltage value; The light valve is disposed in the transmission path of the illumination beam to convert the illumination beam into an image beam; and The projection lens is positioned on the transmission path of the image beam to project the image beam out of the projection device.

9. The projection device according to claim 8, characterized in that, The first voltage value is greater than zero; When the power supply unit starts to provide the driving voltage, the bypass circuit stops providing the discharge path, and the driving voltage of the power supply unit charges the output capacitor, causing the voltage value at the output terminal to rise to the second voltage value. The second voltage value is greater than or equal to the minimum operating voltage value.

10. The projection device according to claim 7 or 8, characterized in that, The bypass circuit includes a bypass capacitor, a bypass resistor, and a bypass switch, wherein: The bypass capacitor is connected in parallel with the bypass resistor, and is connected in series with the bypass switch between the output terminal and the ground terminal.

11. The driving device according to claim 10, characterized in that, When the power supply unit stops providing the driving voltage, the bypass switch is turned on to form the discharge path, and the bypass capacitor discharges the output capacitor and stores part of the electrical energy from the output capacitor; In response to the power supply unit starting to provide the drive voltage, the bypass switch opens to cut off the discharge path, and the bypass resistor discharges the bypass capacitor.

12. The projection device according to claim 10, characterized in that, The capacitance value C2 of the bypass capacitor meets the following requirements: Where C1 is the capacitance value of the output capacitor, Vo is the rated output voltage value of the power supply unit, and V TH This refers to the lowest operating voltage value of the light source unit.

13. The projection device according to claim 10, characterized in that, The drive circuit module further includes a control unit, wherein: The control unit is coupled to the power supply unit and the bypass switch, wherein the control unit controls the conduction state of the bypass switch according to the enable signal provided to the power supply unit.

14. The driving circuit module according to claim 13, characterized in that, The enable signal provided by the control unit is to either stop the power supply unit from providing the drive voltage or to start the power supply unit from providing the drive voltage.

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