TWI604756B - Light source device and control method thereof - Google Patents

Description

Light source device and control method

The invention relates to a light source device and a control method, in particular to a light source device and a control method capable of dynamically and dynamically adjusting an output voltage.

Compared with the light source used in the past, the Light Emitting Diode (LED) has the advantages of energy saving, long component life, no mercury, rich color gamut, no need for warming time and fast response. Diodes have been widely used in light sources for display and illumination. For example, a backlight module of a conventional liquid crystal display panel is a Cold Cathode Fluorescent Lamp (CCFL) as a light source. Nowadays, with the increasing luminous efficiency and the decreasing cost of the light-emitting diode, the light-emitting diode has gradually replaced the cold cathode fluorescent tube as a backlight module light source.

Please refer to FIG. 1 , which is a schematic diagram of a conventional light source device 10 using a light-emitting diode. The light source device 10 includes a voltage converter 102 and light emitting diode strips 104_1 104104_n. And switching units 106_1 to 106_n. The voltage converter 102 provides a single fixed drive voltage VD to the LED strips 104_1~104_n. However, due to non-ideal factors in the process or the purity of the material, the forward voltage required for each of the light-emitting diodes is not completely the same. Therefore, in the case where each of the light-emitting diode strips has the same number of light-emitting diodes, the total forward voltage of all the light-emitting diodes on each of the light-emitting diode strips is also different. In this case, for each of the light-emitting diode strips, if the driving voltage VD provided by the voltage converter 102 is greater than the total forward voltage of the individual light-emitting diode strips, then the individual light-emitting diode lamp There will be additional cross-over voltage on the corresponding switch unit, which will increase the additional power loss and reduce the efficiency of voltage conversion, and may cause the switch unit to overheat. Therefore, how to effectively solve the aforementioned problems has become an important issue in this technical field.

Accordingly, one of the main objects of the present invention is to provide a light source device and a control method capable of dynamically adjusting an output voltage in real time to solve the aforementioned problems.

The invention discloses a light source device, comprising: a plurality of light emitting diode light strips; a voltage converter coupled to the plurality of light emitting diode light strips for converting an input voltage according to a voltage control signal Forming an output voltage; a switch module coupled to the plurality of LED strips for sequentially turning on the plurality of LED strips according to a scan control signal; and a control unit coupled to the The plurality of LED strips and the voltage converter are configured to determine, according to the scan control signal, the LED strip to be turned on and to obtain a preset corresponding to the LED strip to be turned on Driving the voltage value, and accordingly generating the voltage control signal corresponding to the light-emitting diode strip to be turned on to the voltage converter to provide the voltage converter for voltage conversion.

The present invention further discloses a control method for a light source device, the light source device comprising a plurality of light emitting diode light strips, the control method comprising: determining a light emitting diode light strip to be turned on according to a scan control signal And obtaining a preset driving voltage value corresponding to one of the light-emitting diode strips to be turned on; and generating a voltage control signal corresponding to one of the light-emitting diode strips to be turned on according to the preset driving voltage value to a voltage conversion To provide the voltage converter for voltage conversion.

Please refer to FIG. 2, which is a schematic diagram of a light source device 20 according to an embodiment of the present invention. The light source device 20 can be applied to any kind of light source. The light source device 20 includes a voltage converter 202, LED strips 204_1~204_n, a switch module 206, and a control unit 208. Each of the LED strips includes a plurality of LEDs connected in series. For example, each of the light-emitting diode strips of the light source device 20 has m light-emitting diodes, but is not limited thereto.

The voltage converter 202 is configured to convert an input voltage VI into an output voltage VO according to a voltage control signal VC to provide to the LED strips 204_1 204204_n. The switch module 206 is coupled to the LED strips 204_1 - 204_n for sequentially turning on the LED strips 204_1 - 204_n according to a scan control signal SC. Preferably, the scan control signal SC is related to at least one of a turn-on sequence and an on-time of the LED strips 204_1-204_n. In addition, the scan control signal SC may be provided by an image processing chip or other external device, but is not limited thereto. Further, as shown in FIG. 2, the switch module 206 includes switch units 2062_1 to 2062_n and load units 2064_1 to 2064_n. Each switch unit is coupled to a corresponding LED strip. Each switch unit can turn on or off the corresponding LED strip according to the scan control signal SC. More specifically, each switching unit can turn on or off the coupling relationship between the coupled LED strips and the corresponding load unit according to the scan control signal SC to control the current path.

The control unit 208 is coupled to the LED strips 204_1-204_n and the voltage converter 202 for generating voltage according to the scan control signal SC and a plurality of preset driving voltage values corresponding to the LED strips 204_1-204_n. The signal VC is controlled to provide a voltage converter 202 for voltage conversion. As such, the voltage converter 202 will provide a corresponding output voltage to drive the LED strip to be turned on. Preferably, each of the preset driving voltage values is a total forward voltage value of one of the light-emitting diode strips 204_1 to 204_n.

For example, the control unit 208 determines, according to the scan control signal SC, the light-emitting diode light bar that is currently to be turned on, and generates a corresponding driving voltage value corresponding to the light-emitting diode light bar to be turned on. The voltage control signal VC to the voltage converter 202 of the LED strip. In this way, after receiving the voltage control signal VC generated by the control unit 208 corresponding to the light-emitting diode light bar to be turned on, the voltage converter 202 generates a corresponding output voltage VO to provide a connection to be turned on. Light-emitting diode strips. The output voltage VO corresponds to a preset driving voltage value of the LED strip to be turned on. In this case, the voltage converter 202 can drive the light to be turned on according to the voltage control signal VC corresponding to the light-emitting diode strip to be turned on to generate an output voltage VO corresponding to the light-emitting diode strip to be turned on. Diode light bar. At the same time, the corresponding switch unit also conducts a coupling relationship between the LED strip to be turned on and the corresponding load unit according to the scan control signal SC. In this way, the light-emitting diode strip to be turned on will be driven to conduct current through the light-emitting diode strip to be turned on to generate light source illumination.

In short, according to the timing of the conduction and the voltage control signal generated by the control unit 208, the voltage converter 202 can provide a corresponding output voltage for the different LED strips to drive the LED strips. Therefore, the present invention can dynamically adjust the output voltage provided by the voltage converter to provide an appropriate output voltage to the light-emitting diode light bar to be turned on to realize the light source illumination, and can effectively avoid the light-emitting diode lamp. The difference in the total forward voltage of the strip causes additional power loss and overheating of the component.

Please refer to FIG. 3, which is a schematic diagram of an embodiment of the control unit 208 in FIG. The control unit 208 includes a voltage detecting unit 302, a storage unit 304, a decoding unit 306, a multiplexing unit 308, and an operation unit 310. The voltage detecting unit 302 is configured to detect and store the preset driving voltage values VF_1 - VF_n corresponding to the LED strips 204_1 - 204_n to the storage unit 304. Each of the preset driving voltage values is a total forward voltage value of one of the LEDs of the LED strips 204_1 to 204_n. For example, the voltage detecting unit 302 detects the total forward voltage values of the LED strips 204_1 204204_n and stores them into corresponding preset driving voltage values. That is, the total forward voltage value of the LED strip 204_1 is stored as a preset driving voltage value VF_1 corresponding to the LED strip 204_1, and the total forward voltage value of the LED strip 204_1 is stored. The corresponding driving voltage value VF_2 corresponding to the light-emitting diode strip 204_2, and so on. The total forward voltage value of each of the light-emitting diode strips is the sum of the forward voltages of all the light-emitting diodes in each of the light-emitting diode strips. In addition, the voltage detecting unit 302 can detect the total forward voltage value of each LED strip by voltage sensing, current sensing or other sensing methods. In short, the voltage detecting unit 302 can detect the preset driving voltage value corresponding to the LED strip and store it in the storage unit 304 for subsequent operation.

Further, the storage unit 304 is configured to store preset driving voltage values VF_1 - VF_n corresponding to the LED strips 204_1 - 204_n. The decoding unit 306 is configured to generate a decoding signal corresponding to the light-emitting diode strip to be turned on according to the scan control signal SC to indicate the light-emitting diode strip to be turned on. The multiplexing unit 308 is configured to determine, according to the decoded signal, the information of the LED strip to be turned on, and obtain the preset driving voltage value corresponding to the LED strip to be turned on from the storage unit 304, and then correspondingly The preset driving voltage value of the light-emitting diode strip to be turned on is supplied to the arithmetic unit 310. The operation unit 310 is configured to generate a voltage control signal VC to the voltage converter 202 corresponding to the light-emitting diode light bar to be turned on according to a preset driving voltage value corresponding to the light-emitting diode light bar to be turned on to indicate voltage conversion. The device 202 adjusts the magnitude of the output voltage VO.

On the other hand, the scan control signal SC can be a Pulse Width Modulation (PWM) signal. As shown in FIG. 3, the signal scanning control signal SC includes pulse width modulation signals PWM_1~PWM_n, and each pulse width modulation signal corresponds to a different LED light bar. In addition, as shown in FIG. 3, the switching units 2062_1 to 2062_n can be implemented by using a switching transistor, but are not limited thereto. The load units 2064_1 to 2064_n are resistive loads, but are not limited thereto.

Please refer to FIG. 4, which is a schematic diagram of an embodiment of the storage unit 304 in FIG. As shown in FIG. 4, the storage unit 304 includes registers 402_1 to 402_n. The registers 402_1 - 402_n are respectively used to store the preset driving voltage values VF_1 - VF_n corresponding to the LED strips 204_1 - 204_n. For example, after the voltage detecting unit 302 detects the preset driving voltage value VF_1 corresponding to the LED strip 204_1, the preset driving voltage value VF_1 is stored in the register 402_1. After the voltage detecting unit 302 detects the preset driving voltage value VF_2 corresponding to the LED strip 204_2, the preset driving voltage value VF_2 is stored in the register 402_2. Similarly, after the voltage detecting unit 302 detects the preset driving voltage value VF_n corresponding to the LED strip 204_n, the preset driving voltage value VF_n is stored to the register 402_n. That is, the preset driving voltage values VF_1 to VF_n corresponding to the LED strips 204_1 to 204_n are stored in the registers 402_1 to 402_n, respectively.

Please continue to refer to FIG. 4 , if the scanning control signal SC indicates that the LED strip to be turned on is the LED strip 204_1 , the decoding unit 306 generates the corresponding LED strip 204_1 according to the scan control signal SC. The decoding signal is used to indicate that the light-emitting diode light bar to be turned on is the light-emitting diode light bar 204_1. In this case, the multiplex unit 308 can read the preset driving voltage value VF_1 corresponding to the LED strip 204_1 stored by the register 402_1 according to the decoded signal of the corresponding LED strip 204_1, and The preset driving voltage value VF_1 is supplied to the arithmetic unit 310. The operation unit 310 generates a corresponding voltage control signal VC to the voltage converter 202 according to the preset driving voltage value VF_1 corresponding to the LED strip 204_1 to be turned on, to instruct the voltage converter 202 to adjust the magnitude of the output voltage VO. Therefore, the voltage converter 202 can adjust the appropriate output voltage VO according to the voltage control signal VC to drive the LED strip 204_1. For example, the voltage control signal VC can indicate a difference between the preset driving voltage value VF_1 and the voltage value of the current output voltage VO. If the preset driving voltage value VF_1 of the LED strip 204_1 is 31 volts, and the voltage level of the current output voltage VO is 34 volts, the voltage control signal VC can indicate the preset driving voltage value VF_1 and the current output voltage VO. The difference between the voltage values is -3 volts. In this case, the voltage converter 202 can reduce the output voltage VO according to the voltage control signal VC to generate an output voltage VO having a voltage value of 31 volts to drive the LED strip 204_1. At the same time, the switching unit 2062_1 also turns on the coupling relationship between the LED strip 204_1 and the load unit 2064_1 according to the scan control signal SC to turn on the current path. The LED strip 204_1 is illuminated to provide illumination of the source. In short, according to the LED light bar to be turned on indicated by the scan control signal SC, the control unit 208 can dynamically control the voltage converter 202 to adjust the output of the appropriate output voltage VO to drive the LED to be turned on. Body light strip. In this case, the switching unit 2062_1 does not have an extra cross-over voltage, so that there is no problem of external power loss and overheating.

For example, please refer to FIG. 5, which is a signal timing diagram of the light source device 20 in FIG. It is assumed that the scan control signal SC includes pulse width modulation signals PWM_1~PWM_n, and each pulse width modulation signal corresponds to a different light emitting diode light bar. For convenience of description, only a part of the operation cycle of the scan control signal SC (ie, the signal timing of the pulse width modulation signals PWM_1 to PWM_4 in the periods T0 to T4) is illustrated in this embodiment. As shown in FIG. 5, the pulse width modulation signal PWM_1 indicates that the LED strip 204_1 is turned on during the period T1, and the pulse width modulation signal PWM_2 indicates that the LED strip 204_2 is turned on during the period T2. The pulse width modulation signal PWM_3 indicates that the light emitting diode strip 204_3 is turned on during the period T3, and the pulse width modulation signal PWM_4 indicates that the light emitting diode strip 204_4 is turned on during the period T4. The voltage detecting unit 302 can detect that the total forward voltage values of the LED strips 204_1-204_4 are 31 volts, 32 volts, 33 volts, and 34 volts, respectively, and store them as corresponding preset driving voltage values. That is, the preset driving voltage value VF_1 in the register 402_1 is 31 volts, the preset driving voltage value VF_2 in the register 402_2 is 32 volts, and the preset driving voltage value VF_3 in the register 402_3 is 33 volts. The preset driving voltage value VF_4 in the memory 402_4 is 34 volts.

Before the start of the period T1 (for example, during the period T0), the decoding unit 306 of the control unit 208 generates a decoding signal according to the pulse width modulation signal PWM_1 of the scan control signal SC to indicate that the light-emitting diode is to be turned on during the period T1. Light bar 204_1. The multiplexing unit 308 selects the temporary register 402_1 according to the decoded signal and reads the preset driving voltage value VF_1 in the temporary register 402_1 to be supplied to the arithmetic unit 310. The arithmetic unit 310 calculates that the difference between the preset driving voltage value VF_1 and the voltage value of the output voltage VO during the period T0 is 0 volt (ie, 31 volts - 31 volts = 0 volts). The arithmetic unit 310 outputs the voltage control signal VC to indicate that the difference between the preset driving voltage value and the current output voltage VO is 0 volts. Next, during the period T1, the voltage converter 202 maintains the output voltage VO having an output voltage value of 31 volts and supplies it to the light-emitting diode strip 204_1. At the same time, during the period T1, the switching unit 2062_1 also turns on the coupling relationship between the LED strips 204_1 and the load unit 2064_1 according to the pulse width modulation signal PWM_1. Therefore, during the period T1, the LED strip 204_1 will be turned on, and a current flows through the LED strip 204_1 to generate illumination of the source. At this time, the output voltage value provided by the voltage converter 202 is equivalent to the total forward voltage value required for the LED strip 204_1, and the switch unit 2062_1 does not have an additional cross voltage.

Further, before the start of the period T2 (for example, during the period T1), the decoding unit 306 generates a decoding signal according to the pulse width modulation signal PWM_2 to indicate that the light-emitting diode strip to be turned on during the period T2 is a light-emitting diode Polar body light strip 204_2. The multiplexing unit 308 selects the temporary register 402_2 according to the decoded signal and reads the preset driving voltage value VF_2 in the temporary register 402_2 to provide to the arithmetic unit 310. The arithmetic unit 310 calculates that the difference between the preset driving voltage value VF_2 and the voltage value of the output voltage VO during the period T1 is 1 volt (ie, 32 volts - 31 volts = 1 volt). At this time, the arithmetic unit 310 outputs the voltage control signal VC to indicate that the difference between the preset driving voltage value and the current output voltage VO is 1 volt. Next, the voltage converter 202 increases the voltage level of the output voltage VO. During the period T2, the voltage converter 202 outputs an output voltage VO having a voltage value of 32 volts (31 volts +1 volts = 32 volts) and provides the light to the second light. Polar body light strip 204_2. At the same time, during the period T2, the switching unit 2062_2 also turns on the coupling relationship between the LED strips 204_2 and the load unit 2064_2 according to the pulse width modulation signal PWM_2 of the scan control signal SC. Therefore, during the period T2, the LED strip 204_2 will be driven to conduct and a current flows through the LED strip 204_2 to generate illumination of the source. The output voltage value provided by the voltage converter 202 is equivalent to the total forward voltage value required for the LED strip 204_2, and the switching unit 2062_2 does not have an additional cross voltage.

Similarly, by the control of the control unit 208, during the period T3, the voltage converter 202 outputs an output voltage VO having a voltage value of 33 volts to the LED strip 204_3, and the switching unit 2062_3 is modulated according to the pulse width. The signal PWM_3 turns on the coupling relationship between the LED strip 204_3 and the load unit 2064_3 to illuminate the LED strip 204_3. During the period T4, the voltage converter 202 outputs an output voltage VO having a voltage value of 34 volts to the LED strip 204_4, and the switch unit 2062_4 turns on the LED strip 204_4 according to the pulse width modulation signal PWM_4. The coupling relationship with the load unit 2064_4 to illuminate the LED strip 204_4.

In summary, the conventional voltage converter provides a single fixed driving voltage to the LED strip, so that the corresponding switching unit is burdened with additional voltage across, which will cause additional power loss and overheating of the switching unit. In contrast, the embodiment of the present invention can dynamically adjust the output voltage of the voltage converter for the light-emitting diode light bar to be turned on, so as to provide an appropriate output voltage to the light-emitting diode light bar to be turned on. The illumination of the light source can effectively avoid the problem of extra power loss and overheating of the components due to the difference in the total forward voltage of each of the light-emitting diode strips. The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

10, 20‧‧‧ light source device
102, 202‧‧‧ voltage converter
104_1~104_n, 204_1~204_n‧‧‧Lighting diode light bar
106_1~106_n, 2062_1~2062_n‧‧‧Switch unit
206‧‧‧Switch Module
2064_1~2064_n‧‧‧Load unit
208‧‧‧Control unit
302‧‧‧Voltage detection unit
304‧‧‧ storage unit
306‧‧‧Decoding unit
308‧‧‧Multiple units
310‧‧‧ arithmetic unit
402_1~402_n‧‧‧ register
PWM_1~PWM_n‧‧‧ pulse width modulation signal
SC‧‧‧ scan control signal
T0~T4‧‧ cycle
VC‧‧‧ voltage control signal
VD‧‧‧ drive voltage
VI‧‧‧Input voltage
VO‧‧‧ output voltage

Fig. 1 is a schematic view showing a conventional light source device using a light-emitting diode. FIG. 2 is a schematic diagram of a light source device according to an embodiment of the present invention. Figure 3 is a schematic diagram of one embodiment of the control unit in Figure 2. Figure 4 is a schematic diagram of one embodiment of the storage unit in Figure 3. Fig. 5 is a timing chart of the signal of the light source device in Fig. 4.

20‧‧‧Light source device

202‧‧‧Voltage Converter

204_1~204_n‧‧‧Lighting diode strip

206‧‧‧Switch Module

2062_1~2062_n‧‧‧Switch unit

2064_1~2064_n‧‧‧Load unit

208‧‧‧Control unit

SC‧‧‧ scan control signal

VC‧‧‧ voltage control signal

VI‧‧‧Input voltage

VO‧‧‧ output voltage

Claims (13)

A light source device includes: a plurality of light emitting diode light strips; a voltage converter coupled to the plurality of light emitting diode light strips for converting an input voltage into an output voltage according to a voltage control signal a switch module coupled to the plurality of LED strips for sequentially turning on the plurality of LED strips according to a scan control signal; and a control unit coupled to the plurality of The LED light bar and the voltage converter are configured to determine, according to the scan control signal, a light-emitting diode light bar to be turned on and a preset driving voltage value corresponding to a light-emitting diode light bar to be turned on. And generating the voltage control signal corresponding to the light-emitting diode strip to be turned on to the voltage converter to provide the voltage converter for voltage conversion. The light source device of claim 1, wherein the voltage converter generates the output voltage according to the voltage control signal corresponding to the light-emitting diode strip to be turned on, and the output voltage corresponds to the light-emitting diode to be turned on. The preset driving voltage value of the body light bar. The light source device of claim 1, wherein the switch module comprises a plurality of switch units respectively coupled to the plurality of light emitting diode strips, and each switch unit is turned on or off according to the scan control signal A light-emitting diode light strip coupled to the light. The light source device of claim 1, wherein the control unit comprises: a decoding unit configured to generate a decoding signal according to the scanning control signal to indicate a light-emitting diode light bar to be turned on; And storing a plurality of preset driving voltage values corresponding to the plurality of LED strips; a multiplexing unit configured to determine, according to the decoding signal, the LED strip to be turned on, and from the storage unit Obtaining the preset driving voltage value corresponding to the light-emitting diode light bar to be turned on; and an operation unit for generating the corresponding driving voltage value corresponding to the light-emitting diode light bar to be turned on correspondingly The voltage control signal of the LED strip to be turned on is to the voltage converter. The light source device of claim 4, further comprising: a voltage detecting unit configured to detect the plurality of predetermined driving voltage values corresponding to the plurality of light emitting diode strips and to The preset driving voltage values are stored to the storage unit. The light source device of claim 5, wherein each of the predetermined driving voltage values is a total forward voltage value of one of the plurality of light emitting diode strips. The light source device of claim 1, wherein the scan control signal is related to at least one of a turn-on sequence and an on-time of the plurality of light-emitting diode strips. A control method for a light source device, the light source device comprising a plurality of light emitting diode light strips, the control method comprising: determining a light emitting diode light strip to be turned on according to a scan control signal and obtaining corresponding a preset driving voltage value of one of the light-emitting diode strips to be turned on; and generating a voltage control signal corresponding to one of the light-emitting diode strips to be turned on according to the preset driving voltage value to provide a voltage converter The voltage converter performs voltage conversion. The control method of claim 8, wherein the voltage converter generates the output voltage according to the voltage control signal corresponding to the light-emitting diode strip to be turned on, and the output voltage corresponds to the light-emitting diode to be turned on. The preset driving voltage value of the body light bar. The control method of claim 8, further comprising: generating a decoded signal according to the scan control signal to indicate a light-emitting diode light strip to be turned on; and obtaining, according to the decoded signal, a light corresponding to the light to be turned on The preset driving voltage value of the polar light bar; and generating the voltage control signal corresponding to the light emitting diode light bar to be turned on according to the preset driving voltage value corresponding to the light emitting diode light bar to be turned on To the voltage converter. The control method of claim 10, further comprising: detecting the plurality of preset driving voltage values corresponding to the plurality of LED strips and storing the plurality of preset driving voltage values. The control method of claim 11, wherein each of the preset driving voltage values is a total forward voltage value of one of the plurality of LED strips. The control method of claim 8, wherein the scan control signal is related to at least one of a turn-on sequence and an on-time of the plurality of light-emitting diode strips.