WO2021121300A1 - 电流控制电路、方法以及投影设备 - Google Patents
电流控制电路、方法以及投影设备 Download PDFInfo
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- WO2021121300A1 WO2021121300A1 PCT/CN2020/137081 CN2020137081W WO2021121300A1 WO 2021121300 A1 WO2021121300 A1 WO 2021121300A1 CN 2020137081 W CN2020137081 W CN 2020137081W WO 2021121300 A1 WO2021121300 A1 WO 2021121300A1
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B47/00—Circuit arrangements for operating light sources in general, i.e. where the type of light source is not relevant
- H05B47/10—Controlling the light source
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection
Definitions
- This application relates to the field of projection display technology, and in particular to a current control circuit, method, and projection equipment.
- the color wheel is an important device in the existing projection system, which is mainly used to receive light from a light source and emit sequential light in sequence. Due to the light emission requirements of different colors and the difference in the characteristics of phosphors in different segmented areas of the color wheel, the light source has different current requirements in different segmented areas of the color wheel. When the light source is switched between the adjacent segmented areas of the color wheel, it needs to pass through the spoke area between the adjacent segmented areas of the color wheel. In order to avoid the mixing of the sequential light emitted by the color wheel in the spoke area, it is usually necessary to switch off in the spoke area. Light source, and turn on the light source again after the spoke area is over. Therefore, when the light source switches the current in different segments of the color wheel, the current first rapidly drops to zero, and then rises to the required current value again.
- the embodiments of the present application provide a current control circuit, a method, and a projection device, which can realize rapid and stable switching of any current of the light source.
- an embodiment of the present application provides a current control circuit, which is applied to a projection device including at least a light source and a color wheel, the circuit includes a main power circuit, a discharge circuit, and a control circuit; wherein the main power circuit is used to connect the light source; The discharge circuit is connected to the main power circuit; the control circuit is connected to the main power circuit and the discharge circuit.
- the control circuit is used to control the main power circuit to preload the voltage across the light source during the spoke time of the color wheel when the driving current of the light source needs to be switched from small to large.
- the embodiments of the present application provide a current control method, which is applied to a projection device including at least a light source and a color wheel.
- the current control method runs on the above-mentioned current control circuit to perform: the driving current of the light source needs to be as small as In the case of large switching, during the spoke time of the color wheel, the main power circuit is controlled to pre-rise the voltage at both ends of the light source to the voltage value corresponding to the driving current required after switching; and when the driving current of the light source needs to be switched from large to small, During the spoke time of the color wheel, the voltage across the light source is reduced by the discharge circuit to a voltage value corresponding to the driving current required after switching.
- an embodiment of the present application provides a projection device, including a light source, a color wheel, and a current control device; the color wheel is located in the light path of the light source; the current control device is electrically connected to the light source to drive the power source to emit light; wherein, the current control device includes The main power circuit, the discharge circuit and the control circuit; the main power circuit is connected to the light source; the discharge circuit is connected to the main power circuit; the control circuit is connected to the main power circuit and the discharge circuit.
- the control circuit is used when the driving current of the light source needs to be switched from small to large During the spoke time of the color wheel, the main power circuit is controlled to pre-rise the voltage at both ends of the light source to the voltage value corresponding to the driving current required after switching; when the driving current of the light source needs to be switched from large to small, in the color wheel During the spoke time, the voltage across the light source is reduced by the discharge circuit to a voltage value corresponding to the driving current required after switching.
- the current control circuit, method, and projection device provided by the embodiments of the present application are provided with a main power circuit, a discharge circuit, and a control circuit.
- the control circuit when the driving current of the light source needs to be switched from small to large, the color
- the main power circuit is controlled to pre-rise the voltage at both ends of the light source to the voltage value corresponding to the driving current required after switching, so that when the driving current of the light source is switched from a small current to a large current, it skips the moment the light source is turned on From stop working to recovery time, the current of the light source can quickly rise to the driving current required after switching.
- the driving current of the light source needs to be switched from high to low through the control circuit, the voltage across the light source is reduced by the discharge circuit during the spoke time of the color wheel to a voltage value corresponding to the driving current required after switching, so that the light source
- the driving current is switched from a large current to a small current, at the moment the light source is turned on, the two ends of the light source will not bear too high voltage, thereby suppressing the current overshoot. Therefore, when the driving current of the light source is switched between any current magnitude, the steady state has been reached at the moment of switching on, so as to realize fast and stable switching of any current.
- Fig. 1 shows a projection system provided by an embodiment of the present application.
- FIG. 2 shows a schematic diagram of the structure of the color wheel in FIG. 1.
- Fig. 3 shows a block diagram of a current control circuit provided by an embodiment of the present application.
- Fig. 4 shows a schematic structural diagram of a current control circuit provided by an embodiment of the present application.
- Fig. 5 shows a schematic structural diagram of another current control circuit provided by an embodiment of the present application.
- FIG. 6 shows a schematic diagram of the signal of the system control quantity and the state quantity in the current control circuit provided by an embodiment of the present application.
- FIG. 7 shows a schematic flowchart of a current control method provided by an embodiment of the present application.
- FIG. 8 shows a schematic structural diagram of a projection device provided by an embodiment of the present application.
- FIG. 1 schematically shows a projection system 10, which includes a light source control device 11, a light source 12, a color wheel driving device 13, a color wheel 14, a controller 15, and a spatial light modulator 16 and projection lens 17.
- the light source control device 11 is used to drive the light source 12 to emit light
- the color wheel drive device 13 is used to drive the color wheel 14 to move
- the color wheel 14 is used to receive the light emitted by the light source 12 and emit at least two colors of light
- the spatial light modulator 16 is used to According to the image data DATA, at least two colors of light are image-modulated to generate image light
- the projection lens 17 is used for projecting according to the image light to display the projected image.
- the controller 15 is used to control the timing of turning on and off the light source 12 by the light source control device 11, the driving speed of the color wheel driving device 13, and the modulation timing of the spatial light modulator 16 so that the three are compatible.
- the light source control device 11 is used to control the on and off of the light source 12, and the light source 12 is used to receive the driving signal sent by the light source control device 11 and emit light source light, such as blue light source light, and the light source may be a blue light source.
- the light source 12 may also be a light source of other colors, and is not limited to a blue light source.
- the light source may be an ultraviolet light source to emit ultraviolet light.
- the light source 12 may be a semiconductor diode laser light source to provide high-brightness light source.
- the color wheel 14 is located on the light path where the light source light emitted by the light source 12 is located. As shown in FIG. 2, the color wheel 14 includes at least two segmented areas A, at least one of the at least two segmented areas A carries a wavelength conversion material, and the at least two segmented areas A receive light from the light source and Correspondingly emit at least two colors of light, at least one of the at least two colors of light is converted light generated by the wavelength conversion material being excited by the light source, and each segmented area A emits at least one of the two colors of light Color light.
- the color wheel driving device 13 is used to drive the color wheel 14 to move, so that at least two segmented areas A are periodically located on the light path where the light source light is located and correspondingly periodically emit at least two colors of light.
- at least two segmented areas A are arranged along the circumferential direction, and the color wheel driving device 13 drives the color wheel 14 to rotate along the center of the color wheel 14, so that the at least two segmented areas A are periodically located in the light source where the light source is located.
- On the road at least two segmented areas A periodically emit light of at least two colors. Since the brightness and light output requirements of each color are different, the driving current corresponding to the light source 12 in each segmented area A may be different.
- the driving current corresponding to the light source 12 in the first segmented area a1 is the first driving current
- the driving current corresponding to the light source 12 in the second segmented area a2 is the second driving current. Therefore, when the light source 12 is experiencing different segmented areas A, the driving current may need to be adjusted, and the second driving current is the driving current required after adjustment.
- the spoke area B is located between two adjacent segment areas A.
- the light source 12 passes through two adjacent segmented areas A, it is bound to pass through the spoke area B.
- the color wheel 14 emits the mixed light of the colors corresponding to the two adjacent segmented areas A, that is, the spoke light.
- the light source 12 is turned off when the light source 12 passes through the spoke area B, so that the light source 12 does not emit light in the spoke area B. In other words, the light source 12 is turned off when entering the spoke area B, and turned on when leaving the spoke area B.
- the light source 12 When the light source 12 is experiencing two adjacent segmented areas A, the light source 12 is turned off when entering the spoke area A so that the driving current flowing through the light source 12 is zero, and because the light source 12 corresponds to the driving current in the different segmented areas A It may be different. Therefore, after the light source 12 leaves the spoke area B, the driving current of the light source 12 may need to be readjusted to meet the light output requirements of the next segmented area A.
- the inventor found that when the light source is going through two adjacent segmented areas, if the driving current corresponding to the previous segmented area is less than the corresponding driving current of the next segmented area, the light source is turned on again after leaving the spoke area.
- the light source's drive current rises too slowly; and if the drive current corresponding to the previous segment area is greater than the drive current corresponding to the next segment area, the moment the light source is turned on after leaving the spoke area, the voltage across the light source is too large , Resulting in current overshoot.
- the current control circuit in this application is provided with a main power circuit, a discharge circuit, and a control circuit.
- the main power circuit controls the main power circuit to reduce the voltage across the light source during the spoke time of the color wheel.
- the driving current of the light source needs to be switched from high to low through the control circuit, the voltage across the light source is reduced by the discharge circuit during the spoke time of the color wheel to a voltage value corresponding to the driving current required after switching, so that the light source
- the driving current is switched from a large current to a small current, at the moment the light source is turned on, the two ends of the light source will not bear too high voltage, thereby suppressing the current overshoot. Therefore, when the driving current of the light source is switched between any current magnitude, the steady state has been reached at the moment of switching on, so as to realize fast and stable switching of any current.
- FIG. 3 shows a current control circuit 100 provided by an embodiment of the present application.
- the current control circuit 100 specifically includes a main power circuit 110, a discharge circuit 120 and a control circuit 130.
- the discharge circuit 120 is connected to the main power circuit 110, and the control circuit 130 is connected to the main power circuit 110 and the discharge circuit 120.
- the main power circuit 110 is used to connect a light source, and the light source may be a semiconductor laser.
- the discharge circuit 120 is used to reduce the voltage across the light source.
- the control circuit 130 is used to control the timing of switching or turning off the light source of the main power circuit 110 and the discharge timing of the discharge circuit 120.
- the control circuit 130 is also used to control the main power circuit 110 to pre-rise the voltage across the light source to a voltage value corresponding to the required drive current after switching during the spoke time of the color wheel when the driving current of the light source needs to be switched from small to large. And when the driving current of the light source needs to be switched from large to small, the voltage across the light source is reduced by the discharge circuit 120 during the spoke time of the color wheel to a voltage value corresponding to the required driving current after switching.
- the period during which the light source passes through the color wheel segment area is referred to as the segment time
- the period during which the light source passes through the color segment spoke area is referred to as the spoke time.
- the driving current required for the light source in the first segment time is the first driving current
- the driving current required for the light source in the second segment time is the second driving current.
- the first driving current needs to be switched to the second driving current
- the second driving current is the driving current required after switching.
- the first driving current is smaller than the second driving current
- its driving current needs to be switched from a small current to a large current, which also means that the driving current needs to rise.
- the light source turns off; after the spoke time ends, the light source enters the second segment time and turns on again.
- the voltage across the light source is increased in advance from the voltage value corresponding to the first drive current to the voltage value corresponding to the second drive current, that is, before the light source is turned on, the voltage at both ends of the light source is increased in advance.
- the voltage has reached the voltage value corresponding to the second drive current required for the second segment time in advance.
- the system enters the steady state in advance and is ready for the light source to turn on, so that the light source is turned on when the second segment time comes.
- the time for the system to resume operation after the light source is turned on can be skipped, and the current rising speed of the light source can be accelerated, so that the current of the light source quickly reaches the second driving current.
- the light source when the light source is from the first segment time to the second segment time, its driving current needs to be switched from a high current to a low current, which also means that the driving current needs to be reduced.
- the light source When entering the spoke time period, the light source is turned off; after the spoke time ends, the light source enters the second segment time and turns on again.
- the system when the light source is turned off, it enters the spoke time period, that is, the voltage across the light source drops to the voltage value corresponding to the second drive current, that is, before the light source is turned on, the voltage across the light source has dropped to the second
- the voltage value corresponding to the second driving current required for the split time the system enters the steady state in advance and prepares for the light source to turn on, so that the light source will not be subjected to the moment when the light source is turned on when the second split time comes.
- the high voltage corresponding to the first drive current is a low voltage corresponding to the required second drive current, thereby suppressing current overshoot.
- the current control circuit provided by the embodiment of the present application is provided with a main power circuit, a discharge circuit, and a control circuit.
- the main power circuit 110 is controlled during the spoke time of the color wheel.
- the voltage at both ends of the light source pre-rises to the voltage value corresponding to the driving current required after switching, so that when the driving current of the light source is switched from a small current to a large current, the time from stop to recovery is skipped at the moment when the light source is turned on.
- the current can quickly rise to the drive current required after switching.
- the driving current of the light source needs to be switched from large to small through the control circuit of 100 channels, the voltage across the light source is reduced by the discharge circuit 120 during the spoke time of the color wheel to the voltage value corresponding to the required driving current after switching.
- the driving current of the light source is switched from a large current to a small current, at the moment the light source is turned on, the two ends of the light source will not bear too high voltage, thereby suppressing the current overshoot. Therefore, when the driving current of the light source is switched between any current magnitude, the steady state has been reached at the moment of switching on, so as to realize fast and stable switching of any current.
- the main power circuit 110 may be a Buck circuit. In some embodiments, the main power circuit 110 may also be a Boost circuit or the like. Specifically, as shown in FIG. 4, FIG. 4 shows one structure of the main power circuit 110.
- the main power circuit 110 includes a DC power source Source, a first switch S1, a second switch S2, a first capacitor C1, an inductor L1, and a freewheeling diode D1.
- One end of the first switch S1 is connected to the positive pole of the DC power source, and the other end is used to connect to one end of the light source; one end of the inductor L1 is connected in series with the second switch S2 to the negative pole of the DC power source Source, and the other end of the inductor L1 is used to connect the light source The other end; one end of the first capacitor C1 is connected between the first switch S1 and the anode of the DC power source, and the other end is used to connect between the light source and the inductor L1; the anode of the freewheeling diode D1 is connected between the inductor L1 and the second Between the switches S2, the negative pole is connected between the first switch S1 and the positive pole of the DC power source Source. Among them, the first capacitor C1 is connected in parallel with both ends of the light source, and the inductor L1 is connected in series with the light source.
- the discharge circuit 120 is connected in parallel with the first capacitor C1.
- the discharge circuit 120 includes a third switch S3, a first resistor R1, and a second capacitor C2; the first resistor R1 and the second capacitor C2 are respectively connected in parallel at both ends of the first capacitor C1, and one end of the third switch S3 is connected to the first capacitor C1. One end and the other end are connected between the first resistor R1 and the second capacitor C2.
- the structure of the discharge circuit 120 may also be as shown in FIG. 5.
- the discharge circuit 120 includes a third switch S3, a first resistor R1, a Zener diode Z1, and a second capacitor C2; the first resistor R1 and the Zener diode Z1 are connected in series and connected in parallel across the first capacitor C1, and the second capacitor C2 is connected in parallel Two ends of the first capacitor C1, one end of the third switch S3 is connected to one end of the first capacitor C1, and the other end is connected between the first resistor R1 and the second capacitor C2.
- the first switch S1, the second switch S2, and the third switch S3 are all electronic switches.
- the first switch S1, the second switch S2, and the third switch S3 can be any one or a combination of a triode, a field effect transistor, and a thyristor.
- control circuit 130 is connected to the first switch S1, the second switch S2, and the third switch S3.
- the control circuit 130 is used to respectively output control signals to the first switch S1, the second switch S2, and the third switch S3 to control the switching timing of the first switch S1, the second switch S2, and the third switch S3.
- the control circuit 130 controls the on and off of the light source by controlling the switching sequence of the first switch S1.
- the control circuit 130 may be, but is not limited to, a clock chip, a pulse width modulation (PWM) chip, a single-chip microcomputer, etc.
- the control signal may be a PWM signal, a clock signal, and the like.
- the main power circuit 110 includes a charging circuit connected to the light source.
- the control circuit 130 is used to control the charging circuit according to the required driving current after switching during the spoke time of the color wheel. Charging time, and controlling the charging circuit to charge, so as to advance the voltage across the light source to a voltage value corresponding to the driving current required after switching, and the driving current required after switching is the second driving current.
- the charging time can be determined according to the first drive current before the rise and the second drive current after the rise, so that the voltage across the power supply after the charging time reaches the same value as the first drive current.
- the voltage value corresponding to one driving current rises to the voltage value corresponding to the second driving current.
- the charging circuit is composed of the above-mentioned first capacitor C1 and inductor L1.
- the charging circuit may also include not only the aforementioned first capacitor C1 and inductor L1.
- the charging circuit of this embodiment adopts a closed-loop charging method.
- the charging circuit may also adopt an open-loop charging method.
- the control circuit 130 outputs a control signal to the second switch S2, and controls the charging time of the charging circuit by controlling the on time and off time of the second switch S2. Specifically, by controlling the on time of the second switch S2, the first capacitor C1 and the inductor L1 are charged at the same time. After the first capacitor C1 is fully charged, the off time of the second switch is controlled to control the inductor L1 to the first capacitor. Discharging C1 causes the voltage across the first capacitor C1 to rise to a voltage corresponding to the second driving current, so that the voltage across the power supply reaches the voltage value corresponding to the second driving current in advance, and the system enters a steady state in advance. In some embodiments, it is also possible to control the constant current of the inductor current after the inductor L1 is discharged, so that the system reaches a steady state faster.
- the second switch S2 is controlled to be turned on or off by time control, so that the voltage across the light source reaches the voltage corresponding to the second driving current in advance.
- pulse width modulation can also be used to adjust the duty cycle of the control signal to control the on and off of the second switch S2.
- the PWM frequency is controlled to control the on and off of the second switch S2.
- the charging time of the charging circuit is calculated in real time according to the second driving current.
- the charging time corresponding to the second driving current can be determined by looking up a table. Specifically, the charging time corresponding to the driving current of different values is obtained through the test, and the charging time required to reach the second driving current can be determined by means of offline table look-up.
- the control circuit 130 is used to control the discharge time of the discharge circuit 120 according to the driving current required after switching when the light source is turned off, so as to reduce the voltage across the light source to
- the voltage value corresponding to the driving current required after the switching, and the driving current required after the switching is the second driving current.
- the discharge time can be determined according to the first drive current before the drop and the second drive current after the drop, so that the voltage across the power supply after the discharge time reaches the same value as the first drive current.
- the voltage value corresponding to one driving current drops to the voltage value corresponding to the second driving current.
- the control circuit 130 outputs a control signal to the third switch S3, and controls the discharge time of the discharge circuit 120 by controlling the on time of the third switch S3. Specifically, by controlling the on-time of the third switch S3, the first capacitor C1 is discharged to the second capacitor C2, so that the voltage across the first capacitor C1 drops to a voltage corresponding to the second driving current, so that the light source The voltage at both ends drops to the voltage value corresponding to the second drive current, and the system enters the steady state in advance at the same time.
- the third switch S3 is controlled to be turned on by time control, so that the voltage across the light source is reduced to a voltage value corresponding to the second driving current.
- pulse width modulation may also be used to adjust the duty cycle of the control signal, thereby controlling the conduction of the third switch.
- the PWM frequency is controlled to control the on and off of the third switch S3.
- the discharging time of the discharging circuit 120 is calculated in real time according to the second driving current.
- the discharge time corresponding to the second driving current can be determined by looking up a table. Specifically, the discharge time corresponding to the driving current of different values is obtained through the test, and the discharge time required to decrease to the second driving current can be determined by means of offline table look-up.
- Figure 6 shows the control quantity (control signal) and state quantity of the system (the voltage of the first capacitor, the current of the inductor, and the driving current of the light source) over time when the light source switches between different segment areas.
- control quantity control signal
- state quantity of the system the voltage of the first capacitor, the current of the inductor, and the driving current of the light source
- the enable signal EN is the output enable signal of the light source driving current
- the control signal S1 is the control signal output by the control circuit to control the on or off of the first switch S1;
- the control signal S2 It is the control signal output by the control circuit that controls the on or off of the second switch S2;
- the control signal S3 is the control signal output by the control circuit that controls the on or off of the third switch S3;
- the voltage signal C1 is the capacitor voltage of the first capacitor C1 Signal;
- the current signal L1 is the inductor current signal of the inductor L1;
- the current signal S1 is the current signal of the first switch S1.
- the current of the first switch S1 is also equal to the driving current of the light source. Therefore, the current signal S1 can also be expressed as the driving current of the light source.
- the first switch S1, the second switch S2, and the third switch S3 in the embodiment of the present application take N-MOS as an example.
- the light source sequentially goes through the first segmented area, the first spoke area, the second segmented area, the second spoke area, and the third segmented area of the color wheel.
- the second drive current corresponding to the second segmented area is greater than the first drive current corresponding to the first segmented area;
- the third drive current corresponding to the third segmented area is smaller than the second drive standby current corresponding to the second segmented area. That is to say, when the light source is switched from the first segmented area to the second segmented area, the driving current needs to increase; when the light source is switched from the second segmented area to the third segmented area, the driving current needs to decrease.
- the light source has left the first segment area and is located in the first spoke area; at time T2, the light source leaves the first spoke area and enters the second segment area; at time T3, the light source leaves the second segment area and Enter the second spoke area. That is to say, the T0 ⁇ T2 stage is the spoke time period; the T2 ⁇ T3 stage is the first split time period; the T3 ⁇ T6 stage is also the spoke time period.
- the enable signal EN is at a high level, and the light source enters the light-emitting preparation stage, and the control signal S2 is at a high level at the same time.
- the control signal S1 and the control signal S3 are at low level, and the control signal S2 remains at high level.
- the first switch S1 is turned off, the second switch S2 is turned on, and the third switch S3 is turned off. Is closed.
- the DC power source simultaneously charges the first capacitor C1 and the inductor L1, and the voltage signal C1 and the current signal L1 rise simultaneously.
- the voltage across the first capacitor C1 is equal to the voltage across the light source, that is to say, the voltage across the light source is rising at this stage.
- the control signal S2 becomes a low level, and the control signal S1 and the control signal S3 remain unchanged.
- the second switch S2 is turned off.
- the second switch 2 is closed, and the inductor L1 continues to charge the first capacitor C1 at this moment.
- the inductor L1 continues to discharge to the first capacitor C1, and the voltage signal C1 continues to rise until it rises to the value corresponding to the second drive current. Voltage, the system voltage reaches a steady state at this time. In fact, this stage is an additional increase in the voltage of the first capacitor C1. If the voltage across the first capacitor C1 has risen to the voltage corresponding to the second drive current in the T0 ⁇ T1 stage, then the system voltage in the T0 ⁇ T1 stage The steady state can be reached.
- the stages T0 to T2 are all charging stages, so the time from T0 to T2 can be calculated based on the first drive current before the rise and the second drive current required to reach the rise.
- the control signal S1 changes to a high level, the first switch S1 is turned on, and the light source is turned on. At this time, the light source leaves the spoke area of the color wheel and enters the second segment area. Before the light source is turned on, since the voltage across the light source has risen to the voltage value corresponding to the second drive current in advance, it is ready for the light source to turn on. Then at the moment the light source is turned on, the current of the light source is proportional to its voltage. At this moment, the driving current of the light source can quickly rise to the current value corresponding to the second driving current, and the system current quickly enters the constant current closed-loop steady state.
- the control signal S1 maintains a high level, and the light source enters the second segmented area to continuously emit light.
- the control signal S2 controls the second switch S2 to be turned on or off according to actual needs.
- the voltage signal C1 and the current signal L1 are stable to keep the voltage at both ends of the light source stable and the driving current of the light source stable.
- the current signal S1 is constant and the system is in constant current. Closed loop steady state.
- the enable signal EN becomes low level
- the control signal S1 and control signal S2 become low level
- the control signal S3 becomes high level.
- the first switch S1 is turned off
- the second switch S2 is turned off
- the third switch S3 is turned on.
- the light source is turned off and leaves the second segment area of the color wheel and enters the second spoke area.
- the control signal S1 and the control signal S2 are maintained at a low level, and the control signal S3 is maintained at a high level.
- the inductor discharges to the first capacitor C1 and the second capacitor C2, and the first capacitor C1 discharges to the second capacitor C2.
- the current of the inductor L1 drops to zero and the voltage across the first capacitor C1 also continues to drop.
- the control signal remains unchanged, the first capacitor C1 continues to discharge to the second capacitor C2, and the voltage across the first capacitor C1 continues to drop until it drops to a voltage value corresponding to the third driving current.
- the control signal S3 becomes a low level, and the third switch S3 is turned off.
- the voltage across the first capacitor C1 drops to a voltage value corresponding to the third driving current, and the system voltage enters a steady state.
- the stages T3 to T5 are all discharge times, so the time of T3 to T5 can be calculated based on the second drive current before the drop and the third drive current that needs to be dropped.
- the control signal S1, the control signal S2, and the control signal S3 remain low, the voltage across the first capacitor C1 remains unchanged, and the system voltage remains stable, waiting for the light source to turn on and enter the third segment area.
- the light source enters the third segmented area, at the moment when the light source is turned on, since the voltage across the light source has dropped to the voltage corresponding to the third drive current, both ends of the light source will not bear high voltage at this time, so the current flow when the light source is turned on is suppressed Rush.
- the voltage across the first capacitor C1 has dropped to the voltage corresponding to the third drive current during the period T4 to T5
- the system can enter the steady state in advance.
- the third driving current is the same as the second driving current, the discharge of the first capacitor C1 may not be controlled during the period T3 to T4, so that the voltage across the first capacitor C1 remains unchanged, and the system directly enters a steady state.
- the driving current needs to increase, the voltage across the light source is pre-increased to the voltage value corresponding to the required driving current during the spoke time period.
- the current rises rapidly at the moment the light source is turned on, and the system quickly reaches a steady state; if the drive current needs to drop, the voltage across the light source is reduced to the voltage value corresponding to the required drive current during the spoke time, so as to suppress the current flow at the moment the light source is turned on Rush.
- the difference between the segmented currents can be greater, thereby reducing the constraints on the color angle ratio of the color wheel, and the system deviation of the white balance can be corrected by the segmented currents, improving the product yield, and achieving better display effects.
- the current control circuit provided by the embodiment of the present application is provided with a main power circuit, a discharge circuit, and a control circuit.
- the main power circuit controls the main power circuit to switch the light source during the spoke time of the color wheel.
- the voltage at both ends pre-rises to the voltage value corresponding to the driving current required after switching, so that when the driving current of the light source is switched from a small current to a large current, the time from stop to recovery is skipped at the moment the light source is turned on.
- the current of the light source It can quickly rise to the drive current required after switching.
- the driving current of the light source needs to be switched from high to low through the control circuit, the voltage across the light source is reduced by the discharge circuit during the spoke time of the color wheel to a voltage value corresponding to the driving current required after switching, so that the light source
- the driving current is switched from a large current to a small current, at the moment the light source is turned on, the two ends of the light source will not bear too high voltage, thereby suppressing the current overshoot. Therefore, when the driving current of the light source is switched between any current magnitude, the steady state has been reached at the moment of switching on, so as to realize fast and stable switching of any current.
- an embodiment of the present application also provides a current control method 200, which is applicable to the above-mentioned projection system 10, and the method 200 runs the above-mentioned current control circuit.
- the method 200 may include the following steps S210 to S220.
- Step S210 When the driving current of the light source needs to be switched from small to large, the main power circuit is controlled during the spoke time of the color wheel to pre-rise the voltage at both ends of the light source to a voltage value corresponding to the required driving current after switching.
- the voltage across the light source is pre-increased to the voltage value corresponding to the driving current required after switching during the spoke time, so that the moment the light source is turned on The current rises rapidly and the system quickly reaches a steady state.
- Step S220 When the driving current of the light source needs to be switched from high to low, the voltage across the light source is reduced by the discharge circuit during the spoke time of the color wheel to a voltage value corresponding to the driving current required after switching.
- the voltage across the light source is reduced to the voltage value corresponding to the driving current required after switching during the spoke time, so as to suppress the moment when the light source is turned on Current overshoot.
- the main power circuit is controlled during the spoke time of the color wheel to pre-rise the voltage at both ends of the light source to the required driving current after switching
- the corresponding voltage value enables the light source driving current to switch from low current to high current, skipping the time from stop to recovery at the moment the light source is turned on, and the light source current can quickly rise to the driving current required after switching.
- the driving current of the light source needs to be switched from large to small
- the voltage at both ends of the light source is reduced to the voltage value corresponding to the required driving current after switching by the discharge circuit during the spoke time of the color wheel, so that the driving of the light source
- the two ends of the light source do not bear too high voltage, thereby suppressing the current overshoot. Therefore, when the driving current of the light source is switched between any current magnitude, the steady state has been reached at the moment of switching on, so as to realize fast and stable switching of any current.
- an embodiment of the present application further provides a projection device 300, which includes a light source 310, a color wheel 320, and a current control device 330.
- the color wheel 320 is arranged on the light path of the light source 310, and the current control device 330 is electrically connected to the light source 310 to control the light source 310 to emit light.
- the current control device includes the above-mentioned current control circuit; the main power circuit is connected to the light source; the control circuit is used to control the main power circuit to switch the light source at both ends of the light source during the spoke time of the color wheel when the driving current of the light source needs to be switched from small to large.
- the voltage is pre-increased to the voltage value corresponding to the driving current required after switching; when the driving current of the light source needs to be switched from large to small, the voltage at both ends of the light source is reduced to and after switching through the discharge circuit during the spoke time of the color wheel The voltage value corresponding to the required drive current.
- the projection device provided by the embodiment of the application is provided with a main power circuit, a discharge circuit, and a control circuit.
- the main power circuit is controlled to separate the two light sources during the spoke time of the color wheel.
- the voltage at the terminal is pre-increased to the voltage value corresponding to the driving current required after switching, so that when the driving current of the light source is switched from a small current to a large current, the time from stop to recovery is skipped at the moment the light source is turned on, and the current of the light source can be It quickly rises to the drive current required after switching.
- the driving current of the light source needs to be switched from high to low through the control circuit, the voltage across the light source is reduced by the discharge circuit during the spoke time of the color wheel to a voltage value corresponding to the driving current required after switching, so that the light source
- the driving current is switched from a large current to a small current, at the moment the light source is turned on, the two ends of the light source will not bear too high voltage, thereby suppressing the current overshoot. Therefore, when the driving current of the light source is switched between any current magnitude, the steady state has been reached at the moment of switching on, so as to realize fast and stable switching of any current.
- the difference between the segmented currents can be greater, thereby reducing the constraints on the color angle ratio of the color wheel, and the system deviation of the white balance can be corrected by the segmented currents, improving the yield of the product, and achieving a better display effect.
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Abstract
本申请实施例提供了一种电流控制电路、方法以及投影设备，其中电流控制电路应用于至少包括光源和色轮的投影设备，该电路包括主功率电路，用于连接光源；放电电路，连接主功率电路；以及控制电路，连接主功率电路以及放电电路，控制电路用于在光源的驱动电流需要从小至大切换时，在色轮的轮辐时间期间控制主功率电路将光源两端的电压预上升至与切换后所需的驱动电流对应的电压值；并用于在光源的驱动电流需要从大到小切换时，在色轮的轮辐时间期间通过放电电路将光源两端的电压下降至与切换后所需的驱动电流对应的电压值。本申请实施例提供的电流控制电路能够实现光源任意电流快速、稳定地切换。
Description
本申请涉及投影显示技术领域，具体涉及一种电流控制电路、方法以及投影设备。
色轮是现有投影系统中的重要设备，其主要用于接收光源的光线并按顺序射出时序光。由于不同颜色的出光需求和色轮不同分段区域荧光粉特性的差异，使得光源在色轮的不同分段区域有不同的电流需求。当光源在色轮的相邻分段区域切换时，需要经过色轮相邻分段区域之间的轮辐区，而为了避免色轮在轮辐区射出的时序光混合，通常需要在轮辐区关断光源，并在轮辐区结束后再重新开通光源。因此，光源在色轮的不同分段区域切换电流时，电流首先快速地下降为零，然后再重新上升到需要的电流值。
现有技术中，当光源从大电流向小电流切换时，在光源开通的瞬间，往往会产生电流过冲；而当光源从小电流向大电流切换时，在光源开通后，电流上升速度又过慢。因此，现有技术实有改善的必要。
发明内容
鉴于以上问题，本申请实施方式提供一种电流控制电路、方法以及投影设备，能够实现光源任意电流快速、稳定地切换。
第一方面，本申请实施例提供一种电流控制电路，应用于至少包括光源和色轮的投影设备，该电路包括主功率电路、放电电路以及控制电路；其中，主功率 电路用于连接光源；放电电路连接主功率电路；控制电路连接主功率电路以及放电电路，控制电路用于在光源的驱动电流需要从小至大切换时，在色轮的轮辐时间期间控制主功率电路将光源两端的电压预上升至与切换后所需的驱动电流对应的电压值；并用于在光源的驱动电流需要从大到小切换时，在色轮的轮辐时间期间通过放电电路将光源两端的电压下降至与切换后所需的驱动电流对应的电压值。
第二方面，本申请实施例提供一种电流控制方法，应用于至少包括光源和色轮的投影设备，该电流控制方法运行于上述的电流控制电路，以执行：在光源的驱动电流需要从小至大切换时，在色轮的轮辐时间期间控制主功率电路将光源两端的电压预上升至与切换后所需的驱动电流对应的电压值；以及在光源的驱动电流需要从大到小切换时，在色轮的轮辐时间期间通过放电电路将光源两端的电压下降至与切换后所需的驱动电流对应的电压值。
第三方面，本申请实施例提供一种投影设备，包括光源、色轮以及电流控制装置；色轮位于光源的光路；电流控制装置电连接于光源，以驱动电源出光；其中，电流控制装置包括主功率电路、放电电路以及控制电路；主功率电路连接于光源；放电电路连接于主功率电路；控制电路连接主功率电路以及放电电路，控制电路用于在光源的驱动电流需要从小至大切换时，在色轮的轮辐时间期间控制主功率电路将光源两端的电压预上升至与切换后所需的驱动电流对应的电压值；在光源的驱动电流需要从大到小切换时，在色轮的轮辐时间期间通过放电电路将光源两端的电压下降至与切换后所需的驱动电流对应的电压值。
相对于现有技术，本申请实施例提供的电流控制电路、方法以及投影设备，设置有主功率电路、放电电路以及控制电路，通过控制电路在光源的驱动电流需要从小至大切换时，在色轮的轮辐时间期间控制主功率电路将光源两端的电压预上升至与切换后所需的驱动电流对应的电压值，使得光源的驱动电流从小电 流向大电流切换时，在光源开通的瞬间跳过从停止工作到恢复的时间，光源的电流能够快速地上升至切换后所需的驱动电流。同时，通过控制电路在光源的驱动电流需要从大至小切换时，在色轮的轮辐时间期间通过放电电路将光源两端的电压下降至与切换后所需的驱动电流对应的电压值，使得光源的驱动电流从大电流向小电流切换时，在光源开通瞬间，光源两端不承受过高的电压，从而抑制电流过冲。所以，光源的驱动电流在任意电流大小之间切换时，开通瞬间均已达到稳态，从而实现任意电流快速、稳定的切换。
本申请的这些方面或其他方面在以下实施例的描述中会更加简明易懂。
为了更清楚地说明本申请实施例中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本申请的一些实施例，对于本领域技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1示出了本申请实施例提供的一种投影系统。
图2示出了图1中的色轮的结构示意图。
图3示出了本申请实施例提供的一种电流控制电路框图。
图4示出了本申请实施例提供的一种电流控制电路的结构示意图。
图5示出了本申请实施例提供的另一种电流控制电路的结构示意图。
图6示出了本申请实施例提供的电流控制电路中系统控制量和状态量的信号示意图。
图7示出了本申请实施例提供的一种电流控制方法的流程示意图。
图8示出了本申请实施例提供的一种投影设备的结构示意图。
下面详细描述本申请的实施方式，所述实施方式的示例在附图中示出，其中自始至终相同或类似的标号表示相同或类似的元件或具有相同或类似功能的元件。下面通过参考附图描述的实施方式是示例性的，仅用于解释本申请，而不能理解为对本申请的限制。
为了使本技术领域的人员更好地理解本申请方案，下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行清楚、完整的描述。显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
如图1所示，图1示意性地示出了一种投影系统10，该投影系统包括光源控制装置11、光源12、色轮驱动装置13、色轮14、控制器15、空间光调制器16以及投影镜头17。光源控制装置11用于驱动光源12发光，色轮驱动装置13用于驱动色轮14运动，色轮14用于接收光源12发出的光并射出至少两种颜色光，空间光调制器16用于依据图像数据DATA对至少两种颜色光进行图像调制以产生图像光，投影镜头17用于依据图像光进行投影以显示投影图像。控制器15用于控制光源控制装置11对光源12开启及关闭时序、色轮驱动装置13的驱动速度及空间光调制器16的调制时序以使得三者相适应。
具体地，光源控制装置11用于控制光源12的开启与关闭，光源12用于接收光源控制装置11发出的驱动信号并发出光源光，如蓝色光源光，光源可以为蓝色光源。在一些实施方式中，光源12也可以是其他颜色的光源，并不以蓝色光源为限，如光源可以是紫外光源，从而发出紫外光源光。进一步地，光源12可以为半导体二极管激光光源，用以提供高亮度的光源光。
色轮14位于光源12发出的光源光所在的光路上。如图2所示，色轮14包括至少两个分段区域A，至少两个分段区域A中至少一个分段区域A上承载有波长转换材料，至少两个分段区域A接收光源光并对应射出至少两种颜色光，至少两种颜色光中的至少一种颜色光为波长转换材料受光源光激发而产生的转 换光，每个分段区域A射出至少两种颜色光中的一种颜色光。色轮驱动装置13用于驱动色轮14运动，以使至少两个分段区域A周期性的位于光源光所在的光路上并对应周期性的射出至少两种颜色光。本实施方式中，至少两个分段区域A沿圆周方向设置，色轮驱动装置13驱动色轮14沿色轮14中心旋转，使得至少两个分段区域A周期性的位于光源光所在的光路上，从而至少两个分段区域A周期性的射出至少两种颜色光。由于每种颜色的亮度、出光需求不同，光源12在每个分段区域A对应的驱动电流可能不同。例如，光源12在第一分段区域a1对应的驱动电流是第一驱动电流，光源12在第二分段区域a2对应的驱动电流是第二驱动电流。因此，当光源12在经历不同的分段区域A时，驱动电流可能要被调整，并且第二驱动电流即为调整后所需的驱动电流。
相邻两个分段区域A之间为轮辐区B。光源12在经历两个相邻的分段区域A时，势必要经过轮辐区B。当光源12经过轮辐区B时，色轮14射出的是相邻两个分段区域A对应的颜色的混合光，也即轮辐光。通常来说，为了避免轮辐光的产生，在光源12经过轮辐区B时使光源12关闭，使得光源12在轮辐区B不出光。也就是说，光源12在进入轮辐区B时关闭，在离开轮辐区B时开启。
在光源12在经历两个相邻的分段区域A，光源12在进入轮辐区A时被关闭使得流经光源12的驱动电流为零，而由于光源12在不同分段区域A对应的驱动电流可能不同，因此，在光源12离开轮辐区B后光源12的驱动电流可能要被重新调整以适应下个分段区域A的出光需求。
发明人经过严格的测试发现，当光源在经历两个相邻的分段区域时，如果上个分段区域对应的驱动电流小于下个分段区域对应的驱动电流，在离开轮辐区重新开启光源时，光源的驱动电流上升过于缓慢；而如果上个分段区域对应的驱动电流大于下个分段区域对应的驱动电流，在离开轮辐区重新开启光源的瞬间，光源两端承载的电压过大，导致发生电流过冲。
针对这一问题，发明人进行了大量的研究与测试，提出了本申请中的电流控 制电路，该电路可以应用于上述的投影系统，并解决上述的问题。本申请中的电流控制电路设置有主功率电路、放电电路以及控制电路，通过控制电路在光源的驱动电流需要从小至大切换时，在色轮的轮辐时间期间控制主功率电路将光源两端的电压预上升至与切换后所需的驱动电流对应的电压值，使得光源的驱动电流从小电流向大电流切换时，在光源开通的瞬间跳过从停止工作到恢复的时间，光源的电流能够快速地上升至切换后所需的驱动电流。同时，通过控制电路在光源的驱动电流需要从大至小切换时，在色轮的轮辐时间期间通过放电电路将光源两端的电压下降至与切换后所需的驱动电流对应的电压值，使得光源的驱动电流从大电流向小电流切换时，在光源开通瞬间，光源两端不承受过高的电压，从而抑制电流过冲。所以，光源的驱动电流在任意电流大小之间切换时，开通瞬间均已达到稳态，从而实现任意电流快速、稳定的切换。
具体而言，如图3所示，图3示出了本申请实施例提供的一种电流控制电路100。该电流控制电路100具体包括主功率电路110、放电电路120以及控制电路130。放电电路120连接于主功率电路110，控制电路130连接于主功率电路110以及放电电路120。其中，主功率电路110用于连接光源，光源可以为半导体激光器。放电电路120用于降低光源两端的电压。控制电路130用于控制主功率电路110开关或关闭光源的时序以及放电电路120的放电时序。控制电路130还用于在光源的驱动电流需要从小至大切换时，在色轮的轮辐时间期间控制主功率电路110将光源两端的电压预上升至与切换后所需的驱动电流对应的电压值；并在光源的驱动电流需要从大到小切换时，在色轮的轮辐时间期间通过放电电路120将光源两端的电压下降至与切换后所需的驱动电流对应的电压值。
需要说明的是，本申请实施例中，将光源经历色轮分段区域期间称之为分段时间，将光源经历色段轮辐区期间称之为轮辐时间。当光源经历两个相邻的第一分段区域和第二分段区域时，光源需要依次经历第一分段时间、轮辐时间以及第二分段时间。光源在第一分段时间对应所需的驱动电流为第一驱动电流，光源在 第二分段时间对应所需的驱动电流为第二驱动电流。当光源经历两个相邻的第一分段区域和第二分段区域时，需要将第一驱动电流切换到第二驱动电流，第二驱动电流即为切换后所需的驱动电流。
假设第一驱动电流小于第二驱动电流，光源从第一分段时间至第二分段时间时，其驱动电流要从小电流切换到大电流，也意味着驱动电流需要上升。在轮辐时间期间，光源关闭；轮辐时间结束后进入第二分段时间光源重新开启。本实施例中，在轮辐时间期间，预先将光源两端的电压从与第一驱动电流对应的电压值上升至与第二驱动电流对应的电压值，也就是说，在光源开通前，光源两端的电压已经预先达到了与第二分段时间所需的第二驱动电流对应的电压值，系统提前进入稳态并为光源的开启做好了准备，使得在第二分段时间来临时光源开启的瞬间，可以跳过光源开启后系统恢复工作的时间，加快光源的电流上升速度，使光源的电流迅速达到第二驱动电流。
假设第一驱动电流大于第二驱动电流，光源从第一分段时间至第二分段时间时，其驱动电流要从大电流切换到小电流，也意味着驱动电流需要下降。在进入轮辐时间期间时，光源被关闭；轮辐时间结束后进入第二分段时间光源重新开启。本实施例中，在光源关闭时进入轮辐时间期间，即将光源两端的电压下降至与第二驱动电流对应的电压值，也就是说，在光源开通前，光源两端的电压已经下降到了与第二分段时间所需的第二驱动电流对应的电压值，系统提前进入稳态并为光源的开启做好了准备，使得在第二分段时间来临时光源开启的瞬间，光源两端不会承受与第一驱动电流对应的高电压，而是与所需的第二驱动电流对应的低电压，从而抑制电流过冲。
本申请实施例提供的电流控制电路设置有主功率电路、放电电路以及控制电路，通过控制电路100在光源的驱动电流需要从小至大切换时，在色轮的轮辐时间期间控制主功率电路110将光源两端的电压预上升至与切换后所需的驱动电流对应的电压值，使得光源的驱动电流从小电流向大电流切换时，在光源开通的瞬间跳过从停止工作到恢复的时间，光源的电流能够快速地上升至切换后 所需的驱动电流。同时，通过控制电100路在光源的驱动电流需要从大至小切换时，在色轮的轮辐时间期间通过放电电路120将光源两端的电压下降至与切换后所需的驱动电流对应的电压值，使得光源的驱动电流从大电流向小电流切换时，在光源开通瞬间，光源两端不承受过高的电压，从而抑制电流过冲。所以，光源的驱动电流在任意电流大小之间切换时，开通瞬间均已达到稳态，从而实现任意电流快速、稳定的切换。
本实施例中，主功率电路110可以为Buck电路。在一些实施方式中，主功率电路110也可以为Boost电路等。具体地，如图4所示，图4示出了主功率电路110的其中一种结构。主功率电路110包括直流电源Source、第一开关S1、第二开关S2、第一电容C1、电感L1以及续流二极管D1。第一开关S1的一端连接直流电源Source的正极、另一端用于连接光源的一端；电感L1的一端与第二开关S2串联后连接直流电源Source的负极、电感L1的另一端用于连接光源的另一端；第一电容C1的一端连接在第一开关S1与直流电源Source的正极之间、另一端用于连接在光源与电感L1之间；续流二极管D1的正极连接在电感L1与第二开关S2之间、负极连接在第一开关S1与直流电源Source的正极之间。其中，第一电容C1为并联在光源两端，电感L1为与光源串联。
如图4所示，放电电路120与第一电容C1并联。放电电路120包括第三开关S3、第一电阻R1以及第二电容C2；第一电阻R1和第二电容C2分别并联在第一电容C1两端，第三开关S3的一端连接第一电容C1的一端、另一端连接在第一电阻R1与第二电容C2之间。
在一些实施方式中，放电电路120的结构也可以如图5所示。放电电路120包括第三开关S3、第一电阻R1、稳压二极管Z1以及第二电容C2；第一电阻R1与稳压二极管Z1串联后并联在第一电容C1两端，第二电容C2并联在第一电容C1两端，第三开关S3的一端连接第一电容C1的一端、另一端连接在第一电阻R1与第二电容C2之间。
其中，第一开关S1、第二开关S2以及第三开关S3均为电子开关。第一开 关S1、第二开关S2以及第三开关S3可以为三极管、场效应管以及可控硅中的任一种或多种组合。
本实施例中，控制电路130连接第一开关S1、第二开关S2以及第三开关S3。控制电路130用于分别输出控制信号至第一开关S1、第二开关S2以及第三开关S3以控制第一开关S1、第二开关S2以及第三开关S3的开关时序。其中，控制电路130通过控制第一开关S1的开关时序以控制光源的开启和关闭。控制电路130可以是但不限于是时钟芯片、脉冲宽度调制(Pulse width modulation，PWM)芯片、单片机等，该控制信号可以是PWM信号、时钟信号等。
进一步地，主功率电路110包括连接光源的充电电路，当第一驱动电流小于第二驱动电流时，控制电路130用于在色轮的轮辐时间期间根据切换后所需的驱动电流控制充电电路的充电时间，并控制充电电路进行充电，以将光源两端的电压预先上升至与切换后所需的驱动电流对应的电压值，切换后所需的驱动电流也即第二驱动电流。具体地，由于光源两端的电压与电流成一定的关系，因此可以根据上升前的第一驱动电流和上升后的第二驱动电流来决定充电时间，使充电时间到达后电源两端的电压从与第一驱动电流对应的电压值上升到与第二驱动电流对应的电压值。
本实施例中，充电电路由上述的第一电容C1与电感L1构成。在一些实施例方式中，充电电路也可以不仅包括上述的第一电容C1与电感L1。本实施例的充电电路采用闭环充电方式。在一些实施方式中，充电电路也可采用开环充电方式。
控制电路130输出控制信号第二开关S2，通过控制第二开关S2的导通时间与截止时间来控制充电电路的充电时间。具体地，通过控制第二开关S2的导通时间，使第一电容C1与电感L1同时充电，在第一电容C1充电饱和后，再控制第二开关所的截止时间控制电感L1向第一电容C1放电，使第一电容C1两端的电压上升到与第二驱动电流对应的电压，从而使电源两端的电压预先达到与第二驱动电流对应的电压值，系统提前进入稳态。在一些实施方式中，还可以 在电感L1放电后控制电感电流恒流，使系统更快达到稳态。
另外，本实施例是通过时间控制的方式控制第二开关S2导通或截止，进而使光源两端的电压预先达到与第二驱动电流对应的电压。在一些实施方式中，也可以通过脉冲宽度调制，调节控制信号的占空比，进而控制第二开关S2的导通与截止。或者，通过控制PWM频率，以控制第二开关S2的导通与截止。
本实施例中，根据第二驱动电流实时计算充电电路的充电时间。在一些实施方式中，可以通过查表确定与第二驱动电流对应的充电时间。具体地，通过测试得到不同数值的驱动电流对应的充电时间，即可通过离线查表的方式确定达到第二驱动电流所需的充电时间。
进一步地，当第一驱动电流大于第二驱动电流时，控制电路130用于在光源关断时，根据切换后所需的驱动电流控制放电电路120的放电时间，以将光源两端的电压下降至与切换后所需的驱动电流对应的电压值，切换后所需的驱动电流也即第二驱动电流。具体地，由于光源两端的电压与电流成一定的关系，因此可以根据下降前的第一驱动电流和下降后的第二驱动电流来决定放电时间，使放电时间到达后电源两端的电压从与第一驱动电流对应的电压值下降到与第二驱动电流对应的电压值。
控制电路130输出控制信号至第三开关S3，通过控制第三开关S3的导通时间来控制放电电路120的放电时间。具体地，通过控制第三开关S3的导通时间，使第一电容C1向第二电容C2放电，进而使第一电容C1两端的电压下降到与第二驱动电流相对应的电压，从而使光源两端的电压下降到与第二驱动电流对应的电压值，系统同时提前进入稳态。
另外，本实施例是通过时间控制的方式控制第三开关S3导通，进而使光源两端的电压下降到与第二驱动电流对应的电压值。在一些实施方式中，也可以通过脉冲宽度调制，调节控制信号的占空比，进而控制第三开关的导通。或者，通过控制PWM频率，以控制第三开关S3的导通与截止。
本实施例中，根据第二驱动电流实时计算放电电路120的放电时间。在一些实施方式中，可以通过查表确定与第二驱动电流对应的放电时间。具体地，通过测试得到不同数值的驱动电流对应的放电时间，即可通过离线查表的方式确定下降到第二驱动电流所需的放电时间。
如图6所示，图6示出了光源在切换不同的分段区域时，系统的控制量(控制信号)与状态量(第一电容的电压、电感的电流以及光源的驱动电流)随时间变化的示意图。以下将结合图4和图6对本申请实施例的原理下进行说明。需要说明的是，本申请实施例仅以控制信号的时间控制方式为例进行说明，实际上控制信号的控制方式不仅限于此。
首先对图6所示的各个信号进行说明，使能信号EN为光源驱动电流的输出使能信号；控制信号S1为控制电路输出的控制第一开关S1导通或截止的控制信号；控制信号S2为控制电路输出的控制第二开关S2导通或截止的控制信号；控制信号S3为控制电路输出的控制第三开关S3导通或截止的控制信号；电压信号C1为第一电容C1的电容电压信号；电流信号L1为电感L1的电感电流信号；电流信号S1为第一开关S1的电流信号。而第一开关S1的电流也即等于光源的驱动电流，因此，电流信号S1也可表示为光源的驱动电流。另外，本申请实施例中的第一开关S1、第二开关S2以及第三开关S3以N-MOS为例。
在图6中，光源依次经历色轮的第一分段区域、第一轮辐区、第二分段区域、第二轮辐区以及第三分段区域。并且第二分段区域对应的第二驱动电流大于第一分段区域对应的第一驱动电流；第三分段区域对应的第三驱动电流小于第二分段区域对应的第二驱动待电流。也就是说，光源从第一分段区域切换到第二分段区域时，驱动电流需要上升；光源从第二分段区域切换到第三分段区域时，驱动电流需要下降。
在初始T0时刻，光源已离开第一分段区域并位于第一轮辐区；在T2时刻，光源离开第一轮辐区并进入第二分段区域；在T3时刻，光源离开第二分段区域并进入第二轮辐区。也就是说T0～T2阶段为轮辐时间期间；T2～T3阶段为第一 分段时间期间；T3～T6阶段也为轮辐时间期间。
在T0时刻，使能信号EN为高电平，进入光源出光准备阶段，同时控制信号S2为高电平。
在T0～T1阶段，控制信号S1与控制信号S3为低电平，控制信号S2保持高电平；此阶段第一开关S1关断，第二开关S2导通，第三开关S3关断，光源处于关闭状态。此阶段直流电源Source同时为第一电容C1与电感L1充电，电压信号C1与电流信号L1同时上升。而第一电容C1两端的电压等于光源两端的电压，也就是说此阶段光源两端的电压在上升。
在T1时刻，控制信号S2变为低电平，控制信号S1与控制信号S3保持不变。第二开关S2关断。此时由于第一电容C1已经充电饱和，第一电容C1两端的电压已等于电源电压，因此关闭第二开关2，此刻开始由电感L1继续为第一电容C1充电。
在T1～T2阶段时，控制信号S1、控制信号S2以及控制信号S3保持为低电平，电感L1持续向第一电容C1放电，电压信号C1持续在上升直到上升至与第二驱动电流对应的电压，此时系统电压即达到稳态。实际上，此阶段为第一电容C1电压的额外提升值，若在T0～T1阶段第一电容C1两端的电压就已经上升至与第二驱动电流对应的电压，那么在T0～T1阶段系统电压即可达到稳态。另外，T0～T2阶段均为充电阶段，因此T0～T2的时间可以根据上升前的第一驱动电流以及上升所需达到的第二驱动电流来计算。
在T2时刻，控制信号S1变为高电平，第一开关S1导通，光源开通。此时光源离开色轮的轮辐区并进入第二分段区域。在光源开通之前，由于光源两端的电压已经预先上升到了与第二驱动电流对应的电压值，为光源的开通做好了准备，那么在此刻光源开通的瞬间，由于光源的电流与其电压是成正比关系，此刻光源驱动电流能够迅速上升到与第二驱动电流对应的电流值，系统电流迅速进入恒流闭环稳态。
在T2～T3阶段，控制信号S1保持高电平，光源进入第二分段区域持续发光。同时控制信号S2根据实际需求控制第二开关S2导通或关断，电压信号C1与电流信号L1稳定，保持光源两端的电压稳定以及光源的驱动电流稳定，同时电流信号S1恒定，系统处于恒流闭环稳态。
在T3时刻，使能信号EN变为低电平，控制信号S1与控制信号S2变为低电平，控制信号S3变为高电平。第一开关S1关断、第二开关S2关断、第三开关S3导通。此时光源关闭，并离开色轮的第二分段区域进入第二轮辐区。
在T3～T4阶段，控制信号S1与控制信号S2保持为低电平，控制信号S3保持高电平。此阶段电感向第一电容C1和第二电容C2放电，第一电容C1向第二电容C2放电，电感L1的电流下降到零且第一电容C1两端的电压也持续下降。
在T4～T5阶段，控制信号保持不变，第一电容C1持续向第二电容C2放电，第一电容C1两端的电压持续下降直至下降到与第三驱动电流对应的电压值。
在T5时刻，控制信号S3变为低电平，第三开关S3关断。此时第一电容C1两端的电压下降到与第三驱动电流对应的电压值，系统电压进入稳态。可以理解的是，T3～T5阶段均为放电时间，因此T3～T5的时间可以根据下降前的第二驱动电流以及所需下降到的第三驱动电流来计算。
在T5～T6阶段，控制信号S1、控制信号S2以及控制信号S3保持低电平，第一电容C1两端的电压保持不变，系统电压保持稳态，等待光源开通进入第三分段区域。当光源进入第三分段区域时开通的瞬间，由于光源两端的电压已经下降到与第三驱动电流对应的电压，此时光源的两端不会承受高电压，因此抑制光源开通时的电流过冲。实际上，若在T4～T5阶段第一电容C1两端的电压即已下降到与第三驱动电流对应的电压，系统即可提前进入稳态。另外，如果第三驱动电流与第二驱动电流相同，那么在T3～T4阶段可以不控制第一电容C1放电，使第一电容C1两端的电压保持不变，系统直接进入稳态。
综上所述，当光源经历色轮相邻的分段区域时，如果驱动电流需要上升，则在轮辐时间期间将光源两端的电压预先上升至与所需的驱动电流对应的电压值，从而在光源开通瞬间电流快速上升，系统迅速达到稳态；如果驱动电流需要下降，则在轮辐时间期间将光源两端的电压下降至与所需的驱动电流对应的电压值，从而在光源开通瞬间抑制电流过冲。由此，不管光源在切换分段区域时前后的驱动电流相差多大，都能快速、稳定的切换，实现任意分段电流的快速、稳定控制。基于此，分段电流之间可以相差更大，从而减少对色轮各色角度比例的束缚，并且能够通过分段电流纠正白平衡的系统偏差，提升产品的良率，实现更好的显示效果。
本申请实施例提供的电流控制电路，设置有主功率电路、放电电路以及控制电路，通过控制电路在光源的驱动电流需要从小至大切换时，在色轮的轮辐时间期间控制主功率电路将光源两端的电压预上升至与切换后所需的驱动电流对应的电压值，使得光源的驱动电流从小电流向大电流切换时，在光源开通的瞬间跳过从停止工作到恢复的时间，光源的电流能够快速地上升至切换后所需的驱动电流。同时，通过控制电路在光源的驱动电流需要从大至小切换时，在色轮的轮辐时间期间通过放电电路将光源两端的电压下降至与切换后所需的驱动电流对应的电压值，使得光源的驱动电流从大电流向小电流切换时，在光源开通瞬间，光源两端不承受过高的电压，从而抑制电流过冲。所以，光源的驱动电流在任意电流大小之间切换时，开通瞬间均已达到稳态，从而实现任意电流快速、稳定的切换。
如图7所示，本申请实施例还提供一种电流控制方法200，适用于上述的投影系统10，且该方法200运行上述的电流控制电路。该方法200可以包括以下步骤S210～步骤S220。
步骤S210：在光源的驱动电流需要从小至大切换时，在色轮的轮辐时间期间控制主功率电路将光源两端的电压预上升至与切换后所需的驱动电流对应的电压值。
当光源经历色轮相邻的分段区域时，如果驱动电流需要上升，则在轮辐时间期间将光源两端的电压预先上升至与切换后所需的驱动电流对应的电压值，从而在光源开通瞬间电流快速上升，系统迅速达到稳态。
步骤S220：在光源的驱动电流需要从大至小切换时，在色轮的轮辐时间期间通过放电电路将光源两端的电压下降至与切换后所需的驱动电流对应的电压值。
当光源经历色轮相邻的分段区域时，如果驱动电流需要下降，则在轮辐时间期间将光源两端的电压下降至与切换后所需的驱动电流对应的电压值，从而在光源开通瞬间抑制电流过冲。
本申请实施例提供的电流控制方法，通过在光源的驱动电流需要从小至大切换时，在色轮的轮辐时间期间控制主功率电路将光源两端的电压预上升至与切换后所需的驱动电流对应的电压值，使得光源的驱动电流从小电流向大电流切换时，在光源开通的瞬间跳过从停止工作到恢复的时间，光源的电流能够快速地上升至切换后所需的驱动电流。同时，通过在光源的驱动电流需要从大至小切换时，在色轮的轮辐时间期间通过放电电路将光源两端的电压下降至与切换后所需的驱动电流对应的电压值，使得光源的驱动电流从大电流向小电流切换时，在光源开通瞬间，光源两端不承受过高的电压，从而抑制电流过冲。所以，光源的驱动电流在任意电流大小之间切换时，开通瞬间均已达到稳态，从而实现任意电流快速、稳定的切换。
如图8所示，本申请实施例还提供一种投影设备300，该投影设备300包括光源310、色轮320以及电流控制装置330。色轮320设置于光源310的光路上，电流控制装置330电连接于光源310，以控制光源310出光。
其中，电流控制装置包括上述的电流控制电路；主功率电路连接于光源；控制电路用于在光源的驱动电流需要从小至大切换时，在色轮的轮辐时间期间控制主功率电路将光源两端的电压预上升至与切换后所需的驱动电流对应的电压 值；在光源的驱动电流需要从大至小切换时，在色轮的轮辐时间期间通过放电电路将光源两端的电压下降至与切换后所需的驱动电流对应的电压值。
本申请实施例提供的投影设备，设置有主功率电路、放电电路以及控制电路，通过控制电路在光源的驱动电流需要从小至大切换时，在色轮的轮辐时间期间控制主功率电路将光源两端的电压预上升至与切换后所需的驱动电流对应的电压值，使得光源的驱动电流从小电流向大电流切换时，在光源开通的瞬间跳过从停止工作到恢复的时间，光源的电流能够快速地上升至切换后所需的驱动电流。同时，通过控制电路在光源的驱动电流需要从大至小切换时，在色轮的轮辐时间期间通过放电电路将光源两端的电压下降至与切换后所需的驱动电流对应的电压值，使得光源的驱动电流从大电流向小电流切换时，在光源开通瞬间，光源两端不承受过高的电压，从而抑制电流过冲。所以，光源的驱动电流在任意电流大小之间切换时，开通瞬间均已达到稳态，从而实现任意电流快速、稳定的切换。由此，分段电流之间可以相差更大，从而减少对色轮各色角度比例的束缚，并且能够通过分段电流纠正白平衡的系统偏差，提升产品的良率，实现更好的显示效果。
以上所述，仅是本申请的较佳实施例而已，并非对本申请作任何形式上的限制，虽然本申请已以较佳实施例揭示如上，然而并非用以限定本申请，任何本领域技术人员，在不脱离本申请技术方案范围内，当可利用上述揭示的技术内容做出些许更动或修饰为等同变化的等效实施例，但凡是未脱离本申请技术方案内容，依据本申请的技术实质对以上实施例所作的任何简介修改、等同变化与修饰，均仍属于本申请技术方案的范围内。
Claims (10)
- 一种电流控制电路，应用于至少包括光源和色轮的投影设备，其特征在于，包括：主功率电路，用于连接光源；放电电路，连接所述主功率电路；以及控制电路，连接所述主功率电路以及所述放电电路，所述控制电路用于在所述光源的驱动电流需要从小至大切换时，在所述色轮的轮辐时间期间控制所述主功率电路将所述光源两端的电压预上升至与切换后所需的驱动电流对应的电压值；并用于在所述光源的驱动电流需要从大至小切换时，在所述色轮的轮辐时间期间通过所述放电电路将所述光源两端的电压下降至与切换后所需的驱动电流对应的电压值。
- 如权利要求1所述的电流控制电路，其特征在于，所述控制电路用于在所述色轮的轮辐时间期间根据切换后所需的驱动电流控制所述放电电路的放电时间，以将所述光源两端的电压下降至与切换后所需的驱动电流对应的电压值。
- 如权利要求2所述的电流控制电路，其特征在于，所述控制电路用于在所述色轮的轮辐时间期间通过查表确定与切换后所需的驱动电流对应的放电时间。
- 如权利要求1～3任一项所述的电流控制电路，其特征在于，所述主功率电路包括用于连接所述光源的充电电路，所述控制电路用于在所述色轮的轮辐时间期间根据切换后所需的驱动电流控制所述充电电路的充电时间并控制所述充电电路进行充电，以将所述光源电压预上升至与切换后所需的驱动电流对应的电压值。
- 如权利要求4所述的电流控制电路，其特征在于，所述控制电路用于在 所述色轮的轮辐时间期间通过查表确定与切换后所需的驱动电流对应的充电时间。
- 如权利要求4所述的电流控制电路，其特征在于，所述充电电路包括用于与所述光源并联的第一电容以及连接于所述第一电容且用于与所述光源串联的电感，所述控制电路在控制所述充电电路充电时，用于控制所述第一电容以及所述电感同时充电，并在所述第一电容充电饱和后控制所述电感为所述第一电容继续充电，以使所述光源电压预上升至与切换后所需的驱动电流对应的电压值。
- 如权利要求6所述的电流控制电路，其特征在于，所述主功率电路还包括电源、第一开关、第二开关以及续流二极管，所述第一开关的一端连接所述电源的正极、另一端用于连接光源的一端；所述电感的一端与所述第二开关串联后连接所述电源的负极、另一端用于连接所述光源的另一端；所述第一电容的一端连接在所述第一开关与所述电源的正极之间、另一端用于连接在所述光源与所述电感之间；所述续流二极管的正极连接在所述电感与所述第二开关之间、负极连接在所述第一开关与所述电源的正极之间。
- 如权利要求6所述的电流控制电路，其特征在于，所述放电电路与所述第一电容并联，所述放电电路包括第三开关、第一电阻以及第二电容；所述第一电阻和所述第二电容分别并联在所述第一电容两端，所述第三开关的一端连接所述第一电容的一端、另一端连接在所述第一电阻与所述第二电容之间。
- 一种电流控制方法，其特征在于，应用于至少包括光源和色轮的投影设备，所述电流控制方法运行于权利要求1～8中任一项所述的电流控制电路以执行：在所述光源的驱动电流需要从小至大切换时，在所述色轮的轮辐时间期间 控制所述主功率电路将所述光源两端的电压预上升至与切换后所需的驱动电流对应的电压值；以及在所述光源的驱动电流需要从大至小切换时，在所述色轮的轮辐时间期间通过所述放电电路将所述光源两端的电压下降至与切换后所需的驱动电流对应的电压值。
- 一种投影设备，其特征在于，包括：光源；色轮，位于所述光源的光路；以及电流控制装置，电连接于所述光源，以驱动所述电源出光；其中，所述电流控制装置包括权利要求1～8中任一项所述的电流控制电路；所述主功率电路连接于所述光源；所述控制电路用于在所述光源的驱动电流需要从小至大切换时，在所述色轮的轮辐时间期间控制所述主功率电路将光源两端的电压预上升至与切换后所需的驱动电流对应的电压值；在所述光源的驱动电流需要从大至小切换时，在所述色轮的轮辐时间期间通过所述放电电路将所述光源两端的电压下降至与切换后所需的驱动电流对应的电压值。
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