KR20110041979A - Method and apparatus for controlling power of light source in mobile projector - Google Patents

Abstract

PURPOSE: A method and a device for controlling the power of a light source in a mobile projector are provided to prevent thermal runaway of LED which is a light source of a mobile projector. CONSTITUTION: A method for controlling the power of a light source in a mobile projector comprises the following steps. The power consumption of the light source is calculated. The calculated power consumption of the light source is compared with preset power consumption. Current is automatically adjusted according to comparison result value. The light source comprises one or more LEDs or OLEDs. The voltage applied to both ends of the light source is measured. The current flowing in the light source is measured. The current and the voltage which are measured are multiplied. The consumable power of the light source is calculated.

Description

METHOD AND APPARATUS FOR CONTROLLING POWER OF LIGHT SOURCE IN MOBILE PROJECTOR}

The present invention relates to a mobile projector mounted in a mobile communication terminal, and more particularly, to a power control method of a light source such as a light emitting diode (LED) used in a mobile projector.

Recently, in order to overcome the limitation of the display size, a function for displaying information of the mobile communication terminal on an external large display device, such as a TV-OUT function and a connector connection to an external projector device, has been developed. In addition, a mobile projector technology is being developed in which a small projector module is mounted on a mobile communication terminal instead of an external projector device.

In general, mobile projectors use LEDs as light sources. In addition, in order to control the power of the LED, a circuit as shown in FIG. 1 is conventionally used.

1 is a view showing a circuit for controlling the light output of a conventional LED. Referring to FIG. 1, when a current flows through an LED, an mPD (Monitor Photo Diode) detects light to generate a photocurrent. A photocurrent flows through the feedback resistor R to generate a voltage. The voltage is input to the feedback terminal of the automatic power control (APC) LED driver 110 to increase or decrease the LED driving current after comparison with the reference voltage. The power of the light output from the LED is controlled to be constant. This is commonly referred to as APC (Automatic Power Control) operation.

However, when the conventional LED power control method is used for a mobile projector, some problems may occur. This problem will be described with reference to FIG. 2.

2 is a view showing the power consumption of the LED according to the operating temperature and operating time of the conventional LED. The LED is characterized by a decrease in the amount of LED light as the operating environment temperature increases. In particular, among the RGB light sources used for mobile projectors, especially red LEDs, the amount of light decreases rapidly as the operating temperature increases. Light reduction of about -8% per 10 ° C occurs. Therefore, driving a red LED with an APC requires increasing the drive current to compensate for the amount of light that decreases with increasing temperature. 2 (a) shows the LED power consumption according to the operating environment temperature of the LED. This increase in driving current results in an increase in LED heat generation, so when the conventional power control circuit is applied to a mobile projector that does not have a sufficient heat dissipation structure, the increase in driving current results in an increase in heat generation, and the heat generation also increases the temperature. The temperature rise is repeated in a vicious cycle (drive current increase-> heat generation-> temperature rise-> drive current increase) which increases the drive current to compensate for the decreasing amount of light, resulting in a system with thermal runaway. This might be down.

In addition, LEDs have a reduced amount of light due to gradual degradation as the operating time becomes longer. The drive current then increases due to APC operation. 2B illustrates power consumption of the LED over time. In this case, as described above, the driving current is increased to compensate for the amount of light that decreases over time, and the increase of the driving current leads to an increase in heat generation, and the increase in heat generation also causes a temperature rise, and the temperature rise decreases accordingly. The vicious cycle of increasing the drive current is repeated to compensate for this. This increases the probability of causing Sudden Failure of the LED.

Meanwhile, in order to alleviate the above problem, a limit value of the driving current may be set. However, in the RGB sequential projector, when the driving current of one color reaches a limit, the amount of light of the color is relatively insufficient, causing a white point to be distorted. For example, if the R (Red) color current increases with increasing temperature, but reaches a threshold and no longer increases, then the R color can no longer increase the amount of light, so the whitepoint shifts to the B color for further operating temperature increases. (Blue Shift) A problem may occur.

Therefore, the present invention proposes a method and apparatus for maintaining a constant power consumption of the LED rather than maintaining a constant light output of the LED in the mobile projector to solve the above problems. Accordingly, an RGB sequential mobile projector is to provide a method and apparatus for maintaining a constant total power consumption of the RGB LED while maintaining the RGB white point. 　

According to one aspect of the present invention for achieving this, in the power control method of a light source in a mobile projector, the step of calculating the power consumption of the light source, and comparing the calculated power consumption of the light source with a predetermined power value, And automatically adjusting a current flowing to the light source according to a comparison result value, wherein the light source is at least one LED (Light Emitting Diode) or OLED (Organic Light Emitting Diode). The calculating may include measuring a voltage across both ends of the light source, measuring a current flowing through the light source, and calculating a power consumption of the light source by calculating a product of the measured voltage and current. The adjusting of the current flowing to the light source may include a preset power value and the calculated light source. Calculating the difference with the power consumption, subtracting and outputting the calculated difference value to a preset current value, and receiving the output signal and changing the output voltage to the light source according to the output signal Characterized in that it comprises a.

According to another aspect of the present invention, in the apparatus for controlling the power of a light source in a mobile projector, the power calculation unit for calculating the power of the light source, and the power calculated by the power calculation unit by comparing the power value set in advance with the comparison And a current adjuster for automatically adjusting a current flowing to the light source according to a result value, wherein the light source is at least one light emitting diode (LED) or organic light emitting diode (OLED). A voltage measuring unit measuring a voltage across both ends of the light source, a current measuring unit measuring a current flowing through the light source, and a calculating unit calculating a power consumption of the light source by calculating a product of the measured voltage and current. The current controller is a difference between the preset power value and the power consumption of the light source calculated by the calculator. A comparator for calculating a; It characterized in that it comprises a switch unit to.

The present invention applies the automatic power consumption control (APCC) to maintain a constant power consumption of the light source according to the characteristics of the present invention instead of the APC method for controlling the light output of the conventional light source thermal runaway of the LED as a light source of the mobile projector (Thermal Runaway) can be prevented.

In addition, the LED power consumption can be set and adjusted easily. This can eliminate the trial and error and complexity of maintaining overall power consumption, especially in RGB LED sequential driving.

In addition, the LED driver can be used as a power calibration building block when configuring an application specific integrated circuit (ASIC).

In addition, complex programming can be simplified during power calibration, and the white point can be reduced by adjusting the power while maintaining the RGB current ratio.

1 is a view showing a circuit for controlling the light output of a conventional LED
2 is a view showing the power consumption of the LED according to the operating temperature and operating time of the conventional LED
3 is a diagram illustrating a circuit for controlling power of an LED according to a first embodiment of the present invention;
4 is a diagram illustrating a circuit for controlling power of an LED according to a second exemplary embodiment of the present invention.
5 is a diagram illustrating a circuit for controlling power of an LED according to a third embodiment of the present disclosure.
6 is a diagram illustrating a circuit for controlling power of an LED according to a fourth embodiment of the present disclosure.
7 is a diagram illustrating an example of an enable signal and an output frame of a timing adjusting unit in a circuit for controlling power of an LED according to a second embodiment of the present disclosure;
8 is a view showing a flow of power control operation of the LED according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an apparatus and an operation method of the present invention will be described in detail with reference to the accompanying drawings. In the following description, specific matters such as specific elements are shown, which are provided to help a more general understanding of the present invention. It is self-evident to those of ordinary knowledge in Esau. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

In the present invention, the light source includes a light emitting diode (LED) and an organic light emitting diode (OLED).

The present invention includes a hardware block (H / W Block) that can monitor the power consumption of the LED to solve the problems of the prior art. 3 is a diagram illustrating a circuit for controlling power of an LED according to a first embodiment of the present invention.

Referring to FIG. 3, the circuit 300 for controlling the power of the LED according to the first embodiment of the present invention includes a power calculation unit 31 that greatly calculates the power of the LED, and compares the calculated power with a preset power. Comparing with the current control unit 32 for controlling the current flowing to the LED.

The power calculation unit 31 is a voltage measuring unit 310 for measuring the voltage across the LED, a current measuring unit 320 for measuring the LED current, and a calculation unit for calculating the product of the measured voltage and current 330, wherein the current controller 32 includes a comparator 340 for calculating a difference between a preset power value WATT SET and a power consumption value calculated by the calculator 330, and the comparator ( The dimming unit 350 adjusts dimming by receiving the difference value calculated in step 340 and the preset current value ISET, and receives an output signal of the dimming unit 350 to the LED according to the received output signal. It includes a switch unit 360 for changing and outputting the output voltage. The power control circuit of the LED of the present invention as described above is called APCC (Automatic Power Consumption Control) to avoid confusion with the conventional APC.

Referring to FIG. 3, VIN may be a mobile phone lithium ion (Li +) battery power as a power supply voltage. The switch unit 360 may use a boost-boost converter as a DC-DC converter. VOUT is an output voltage of the switch unit 360 and changes according to the FB input. When the ISET signal is input to the dimming unit 350, a constant current flows in the LED. The voltage measuring unit 310 measures the voltage applied to the LED at this time. The current measuring unit 320 measures the LED current from the voltage generated by the current flowing through the resistor Rsens. The calculation unit 330 multiplies the measured voltage and current, compares the WATT SET value, which is a preset power value, and calculates an increase / decrease and inputs it to the dimming unit 350. The dimming unit 350 adds or subtracts a current increase or decrease from the initially set ISET value, and outputs an FB signal to the switch unit 360. The switch 360 maintains the desired power to be consumed by the LED by adjusting the current flowing to the LED.

4 is a diagram illustrating a circuit for controlling power of an LED according to a second embodiment of the present invention. 4 illustrates an APCC block used when a light source including a pair of red, green, and blue light emitting diodes (LEDs) or organic light emitting diodes (OLEDs) is sequentially driven. .

As shown in FIG. 4, the circuit 400 for controlling the power of the LED according to the second embodiment of the present invention includes a power calculation unit 41 that greatly calculates the power of the LED, and the power calculation unit 41. Comparing the power calculated in the) with a predetermined power is composed of a current control unit 42 for adjusting the current flowing to the LED according to the comparison value.

The power calculator 41 includes a voltage measuring unit 410 for specifying a voltage across the RGB LEDs, a current measuring unit 420 for measuring the current of each RGB LED, and the measured voltage and current. And a calculation unit 430 that calculates a total power of the RGB LED by using a product, wherein the current controller 42 includes a power consumption value calculated by the preset power value WATT SET and the calculation unit 430. A comparator 440 for calculating a difference, a dimming unit 450 for receiving a difference value calculated by the comparator 440 and a preset current value RSET, GSET, and BSET, and adjusting dimming; A switch unit 460 that receives the output signal of the unit 450 and changes the output voltage to the LED according to the received output signal, and outputs the REN (RED_ENABLE) and GEN (GREEN_ENABLE) to adjust the timing of each LED. To control time-sharing of three transistors by receiving BEN (BLUE_ENABLE) signal from outside And a humming adjuster 470.

In the second embodiment of the present invention, the operation is started in the state in which three RGB currents exist and an initial current value determined by white point calibration is set. As shown in FIG. 3, the voltage measuring unit 410 and the current measuring unit 420 measure the voltage and current of each of the RGB LEDs, and the calculation unit 430 calculates the RGB LED total power consumption. In this case, the total power consumption may be calculated by Equation 1 below.

In Equation 1, W is the total power consumption of the LED, i is R or G or B, V is the voltage of the LED, I is the current of the LED, D is the duty ratio of each of the RGB in sequential driving (Duty Ratio).

The comparator 430 compares the calculated W value with a preset W0 to calculate an increment ΔW and inputs it to the dimming unit 450. The dimming unit 450 sequentially divides the FB signal so as to adjust the current of each RGB, and sequentially outputs the FB signal to the switch unit 460. The RGB LED current is changed by the switch unit 460, and the feedback is operated so that the total power consumption is maintained at W0. Reducing or increasing the current in the dimming unit 450 is performed by generating an FB signal to maintain an initially set RGB SET (RGB Setting) ratio. Therefore, even if the RGB current changes to maintain W = W0, the change in the white point and color temperature can be suppressed accordingly.

On the other hand, the timing adjusting unit 470 receives the REN, GEN, BEN signals from the outside in order to adjust the timing of each LED to time-sharing control of the three transistors. An operation of the timing adjusting unit 470 will be described with reference to FIG. 7. FIG. 7 is a diagram illustrating an example of an enable signal and an output frame of a timing adjusting unit in a circuit for controlling power of an LED according to a second embodiment of the present disclosure. As shown in FIG. 7, the timing adjusting unit 470 adjusts the corresponding transistor according to the enable signal received from the outside so that a current flows in the corresponding LED during the timeslot.

5 is a diagram illustrating a circuit for controlling power of an LED according to a third exemplary embodiment of the present invention. If a slight error is allowed in LED power consumption control, the power control circuit may be simply configured by omitting the voltage measuring units 310 and 410 and the current measuring units 320 and 420 of FIGS. 3 and 4. Instead, the VIN input unit is provided with a supply current measuring unit 510 for measuring a supply current supplied to the entire LED driver. By multiplying the supply current measurement by VIN (up to 3.7V) and again by the LED driver's power efficiency (up to 90%), the LED power dissipation W can be approximated and calculated. In practical mobile projector applications, it is more realistic to limit the LED driver supply current than to limit the LED power consumption, which simplifies the circuit in this way.

Accordingly, referring to FIG. 5, the circuit 500 for controlling the power of the LED according to the third embodiment of the present invention includes a power calculator 51 that greatly calculates power consumption of the LED, and predicted power of the LED. It is composed of a current control unit 52 for comparing the current with the preset power to adjust the current flowing to the LED according to the comparison value.

The power calculation unit 51 measures the supply current supplied to the LED and multiplies the measured value by VIN (~ 3,7V) and the power efficiency (~ 90%) of the LED driver to calculate an approximate value of the LED power consumption. The measurement unit 510 is included. The current controller 52 may include a comparator 540 for calculating a difference between a preset power value WATT SET and an approximation value of the power calculated by the supply current measuring unit 510, and the comparator 540. The dimming unit 530 receives the difference value and the preset current value ISET and adjusts the dimming, and receives the output signal of the dimming unit 530 to change the output voltage to the LED according to the received output signal It includes a switch unit 520 to output.

6 is a diagram illustrating a circuit for controlling power of an LED according to a fourth embodiment of the present invention. FIG. 6 illustrates a power control circuit used when a light source including a pair of red, green, and blue colors of a light emitting diode (LED) or an organic light emitting diode (OLED) is sequentially driven. Illustrated.

In mobile systems such as mobile phones, it is common to use a battery as a power source and load power consumption to approximate supply current. Therefore, if the current supplied from the battery is kept constant, the power consumption of the LED is also approximately constant.

However, when using the supply current measuring unit 510 as in the third embodiment of the present invention shown in FIG. 5, the following problem may occur. First, an element for measuring resistance, etc. must be added to a path through which current flows, but there is a disadvantage in that space is insufficient and cost is increased when mounting. In addition, since power consumption occurs in the supply current measuring unit 510, power efficiency is reduced. For example, if the resistance for measuring current is 0.1 Ohm and the supply current is 400mA, 16mW of power is consumed, which is about 1.6% power efficiency reduction. There is also a problem of inaccuracy in supply current measurement (typically ± 5%, with an error of approximately ± 20mA assuming a 400mA supply current).

The fourth embodiment of the present invention uses the supply voltage measuring unit 610 instead of the supply current measuring unit 510 used in the second embodiment to improve such disadvantages, LED at each timing (Timing) RGB LED voltage measuring unit 640 for measuring the driving voltage of the.

Looking at the LED power consumption formula disclosed in Equation 2, Vi is the driving voltage of the RGB LED, Ii is the driving current of the RGB LED, Di is the duty ratio of the RGB LED, V _DD is the supply voltage (Supply Voltage) Where I _DD represents the supply current and η represents the power conversion efficiency of the LED driver. By modifying Equation 2, Equation 3 below can be obtained.

In Equation 3, Vi is a measured value, Ii is a set value, Di is a predetermined value, V _DD is a measured value, and η is a known value of about 90%.

Therefore, I _DD can be calculated by Equation 3, and this value can be calculated more accurately than the value measured by the supply current measuring unit 510 of the third embodiment. This is because the accuracy of Ii is about ± 1% and η is about 90 ~ 92%.

The calculation of Equation 3 may use a software method of transferring the measured V _DD and Vi to a PC outside the chip using a communication protocol such as I 2 C, and then calculating the data at the PC. In this case, the complexity of the system can be reduced, which is efficient. After comparing the calculated I _DD value with the target I _DD value, the new R, G, B LED current setting value is written to the chip register, thus supplying current value, that is, LED power consumption. Can be kept approximately constant.

Looking at the configuration of the circuit 600 for controlling the LED power according to the fourth embodiment of the present invention, the circuit 600 for controlling the power of the LED according to the fourth embodiment of the present invention is largely the supply voltage and The power calculation unit 61 for calculating the power of the LED by measuring the LED driving voltage, and compares the power calculated by the power calculation unit 61 with the preset power to adjust the current flowing to the LED according to the comparison value It consists of a current regulator 62.

The power calculator 61 measures the voltage across the RGB LED and outputs the measured values (RSENS, GSENS, BSENS) to the outside, and a supply for measuring the supply voltage. The voltage measuring unit 610 is included.

The current adjusting unit 62 compares the supply current values of the light sources, which are externally calculated based on the current values RSET, GSET, and BSET of the respective light sources, and the measured values of the power calculating unit 61, respectively. A dimming unit 630 for time-dividing the output value according to each RGB light source by adding or subtracting a difference value to maintain a constant power consumption of the light source, and receiving the output signal of the dimming unit 630 and receiving the LED according to the received output signal. The switch unit 620 adjusts the output voltage so that the total power consumption maintains the preset power value by changing the output voltage of the furnace, and REN (RED_ENABLE), GEN (GREEN_ENABLE), BEN (BLUE_ENABLE) to adjust the timing of each LED. A timing adjuster 650 for time-division control of the three transistors.

The LED power consumption W is calculated by the LED voltage measuring unit 640 and the supply voltage measuring unit 610, and using the equation (3) to calculate the supply current of the LED, VIN to the calculated supply current It is calculated by multiplying by (3.7V max) and again by multiplying the LED driver's power efficiency (up to 90%).

Meanwhile, VIN shown in FIG. 6 may be a mobile phone lithium ion (Li +) battery power source with a power supply voltage. The switch unit 620 may use a boost-boost converter as a DC-DC converter. VOUT is an output voltage of the switch unit 620 and varies with FB input.

8 is a view showing the flow of the power control operation of the LED according to an embodiment of the present invention. Referring to FIG. 8, in operation 610, the total power consumption of the LED is calculated in operation 610. In this case, a power calculation scheme according to each embodiment of the present invention is used. In step 820, the preset power value is compared with the power calculated in step 810. In operation 830, the current flowing to the LED is adjusted according to the comparison result value in operation 820. In this case, the current flowing through the LED is adjusted so that the power consumption of the LED remains constant to a desired degree.

As described above, the operation and configuration of the power control method and apparatus of the light source in the mobile projector according to the embodiment of the present invention can be made, while the above description of the present invention has been described with respect to specific embodiments, but various modifications of the present invention. It can be carried out without departing from the scope of.

Claims (30)

In the power control method of the light source of the mobile projector,
Calculating the power consumption of the light source,
And comparing the calculated power consumption of the light source with a preset power value, and automatically adjusting a current flowing to the light source according to the comparison result value. The method of claim 1, wherein the light source is at least one light emitting diode (LED) or organic light emitting diode (OLED). The method of claim 2, wherein the calculating of power consumption of the light source comprises:
Measuring a voltage across both ends of the light source;
Measuring a current flowing through the light source;
And calculating power consumption of the light source by calculating a product of the measured voltage and current. The method of claim 3, wherein the adjusting of the current flowing to the light source comprises:
Calculating a difference between a preset power value and the calculated power consumption of the light source;
Outputting by subtracting and outputting the calculated difference value to a preset current value;
And changing the voltage output to the light source according to the output. The power of the light source of claim 1, wherein the light source comprises a pair of red, green, and blue light emitting diodes (LEDs) or organic light emitting diodes (OLEDs). Control method. The method of claim 5, wherein the calculating of power consumption of the light source comprises:
Measuring a voltage across the light sources;
Measuring a current flowing through each of the light sources;
And calculating a total power consumption of each light source by using the measured voltage and current of each light source. The method of claim 6, wherein the adjusting of the current flowing to the light source comprises:
Calculating a difference between a preset power value and the total power consumption of the light source calculated by the calculator;
Time-dividing and outputting an output value according to each RGB light source to adjust each current of the RGB light source by adding or subtracting the difference value calculated by the comparator to the current value of each light source;
Receiving the output signal and changing an output voltage to the light source according to the output signal,
The time division and outputting process may include outputting an output value according to each light source so as to maintain a ratio of current values of the respective light sources, and changing the output voltage to the light source may include total power consumption in advance. And controlling the output voltage to maintain the set power value. The method of claim 6, wherein the calculating of the total power consumption of the light source is performed.
A method of controlling power of a light source according to claim 1, wherein the total power consumption is calculated by summing voltage, current, and the product of the duty ratio of each light source in sequential driving. The method of claim 2, wherein the calculating of power consumption of the light source comprises:
And measuring a supply current supplied to the light source, and calculating an approximation of power consumption of the light source by multiplying the measured value by an input voltage and a power efficiency of the light source driver. The method of claim 9, wherein the adjusting of the current flowing to the light source comprises:
Calculating a difference between a preset power value and an approximate value of power consumption of the light source calculated by the supply current measuring unit;
Outputting by subtracting and outputting a difference value calculated by the comparator to a preset current value;
Receiving the output signal and changing the output voltage to the light source according to the output signal. In the device for controlling the power of the light source of the mobile projector,
A power calculator for calculating the power of the light source;
And a current controller configured to automatically adjust the current flowing to the light source according to the comparison result value by comparing the power calculated by the power calculator with a preset power value. The apparatus of claim 11, wherein the light source is at least one light emitting diode (LED) or organic light emitting diode (OLED). The method of claim 12, wherein the power calculation unit
A voltage measuring unit measuring a voltage applied to both ends of the light source;
A current measuring unit measuring current flowing through the light source;
And a calculator configured to calculate power consumption of the light source by calculating a product of the measured voltage and current. The method of claim 13, wherein the current control unit
A comparator for calculating a difference between a preset power value and power consumption of the light source calculated by the calculator;
A dimming unit configured to subtract and output a difference value calculated by the comparator to a preset current value;
And a switch unit configured to receive an output signal of the dimming unit and change an output voltage to the light source according to the output signal of the dimming unit. The power of the light source of claim 11, wherein the light source comprises a pair of red, green, and blue light emitting diodes (LEDs) or organic light emitting diodes (OLEDs). controller. The method of claim 15, wherein the power calculation unit
A voltage measuring unit measuring a voltage applied to both ends of each light source;
A current measuring unit measuring current flowing through each of the light sources;
And a calculator configured to calculate the total power consumption of each light source by using the measured voltage and current of each light source. The method of claim 16, wherein the current control unit
A comparator for calculating a difference between a preset power value and the total power consumption of the light source calculated by the calculator;
Time-divided output value according to each RGB light source to adjust each current of the RGB light source by adding or subtracting the difference value calculated by the comparator to the current value of each preset light source, and outputting the ratio of the current value of each preset light source A dimming unit for outputting an output value according to each light source to maintain a;
And a switch unit configured to receive an output signal of the dimming unit, change an output voltage to the light source according to the output signal of the dimming unit, and adjust an output voltage so that total power consumption is maintained at a preset power value. Power control device. The method of claim 17, wherein the calculation unit
The total power consumption of the light source, characterized in that for calculating the total power consumption by the sum of the product of the voltage, the current, and the duty ratio of each light source in sequential driving for each light source. The method of claim 12, wherein the power calculation unit
And a supply current measuring unit measuring a supply current supplied to the light source and calculating an approximation of power consumption of the light source by multiplying the measured value by an input voltage and the power efficiency of the light source driver. Device. The method of claim 19, wherein the current control unit
A comparator for calculating a difference between a preset power value and an approximate value of power consumption of the light source calculated by the supply current measuring unit;
A dimming unit configured to subtract and output a difference value calculated by the comparator to a preset current value;
And a switch unit configured to receive an output signal of the dimming unit and change an output voltage to the light source according to the output signal of the dimming unit. The method of claim 14, 17, 20, 20, wherein the switch unit
Power control device of the light source, characterized in that the DC-DC converter (Converter). The method of claim 14, 17, 20, 20, wherein the switch unit
Power control device of the light source, characterized in that the Boost-Boost Converter. In the device for controlling the power of the light source of the mobile projector,
A power calculation unit for calculating the power of the light source by measuring a supply voltage and a driving voltage of the light source;
And a current controller configured to automatically adjust the current flowing to the light source according to the comparison result value by comparing the power calculated by the power calculator with a preset power value. 24. The power of the light source according to claim 23, wherein the light source comprises a pair of red, green, and blue light emitting diodes (LEDs) or organic light emitting diodes (OLEDs). controller. The method of claim 24, wherein the power calculation unit
A driving voltage measuring unit measuring a voltage applied to both ends of each of the light sources;
It includes a supply voltage measuring unit for measuring the supply voltage of each light source,
The power control device of the light source, characterized in that for calculating the supply current of the light source using the measured value measured by the driving voltage measuring unit and the supply voltage measuring unit. The method of claim 25, wherein the current control unit
A dimming unit for comparing the current value of each preset light source with the calculated supply current of the light source, time-dividing the output value according to each RGB light source by adding or subtracting a difference value to maintain a constant power consumption of each preset light source; ,
And a switch unit configured to receive an output signal of the dimming unit, change an output voltage to the light source according to the output signal of the dimming unit, and adjust an output voltage so that total power consumption is maintained at a preset power value. Power control device. In the method for controlling the power of the light source of the mobile projector,
Calculating the power of the light source by measuring the supply voltage and the driving voltage of the light source,
And comparing the calculated power with a preset power value to automatically adjust a current flowing to the light source according to the comparison result value. The power of the light source according to claim 27, wherein the light source comprises a pair of red, green, and blue color light emitting diodes (LEDs) or organic light emitting diodes (OLEDs). Control method. The method of claim 28, wherein the calculating of the power of the light source by measuring the supply voltage and the driving voltage of the light source comprises:
Measuring a voltage across the light sources;
Measuring a supply voltage of each light source;
And calculating a supply current of a light source by using the measured value measured by the driving voltage measuring unit and the supply voltage measuring unit. 30. The method of claim 29, wherein comparing the calculated power with a preset power value and automatically adjusting the current flowing to the light source according to the comparison result value,
Comparing the current value of each preset light source with the calculated supply current of the light source, time-dividing the output value according to each RGB light source by adding or subtracting a difference value to maintain a constant power consumption of each preset light source, and
And changing the output voltage to the light source according to the output signal, and adjusting the output voltage to maintain a predetermined power value.

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