TWI389453B - Light emitting diode drive - Google Patents

Description

Light-emitting diode driving device

The invention relates to a light-emitting diode driving device, in particular to use a positive edge and/or a negative edge of a clock input signal to drive a plurality of light-emitting diode strings.

Light Emitting Diode (LED) has been applied to many electronic devices because of its high photoelectric conversion efficiency, high operational stability, and brightness control by Pulse Width Modulation (PWM). Light source or display element, such as the backlight of the display, lighting, advertising viewing, image pixels of a large display.

The illuminating mechanism of the illuminating diode uses the driving current, that is, the higher the driving current, the higher the brightness of the illuminating diode. Therefore, the illuminating diode is preferably connected in series and driven at a constant current. To improve the uniformity of the brightness of the light-emitting diode. As the number of light-emitting diodes increases and is limited by the wiring of the light-emitting diodes, the series-connected light-emitting diodes are typically connected in parallel to form a larger surface light source or display.

The conventional technique is to use a plurality of serially connectable drivers, each of which is connected to a plurality of serially connected LED strings, and receives a data input signal, a clock input signal, an output enable signal, and a latch input signal. To drive the LED string, and simultaneously transmit the data input signal, the clock input signal, the output enable signal, and the latch input signal to the driver of the next stage to drive the connected LED string, and so on. .

However, the disadvantage of the conventional technology is that the LED driver requires four input signals to four output signals, so a large number of connecting lines are required, and different lengths of the connecting lines generate signal delays, which affect the overall light emitting diode. Luminous performance. Another disadvantage of the conventional technology is that the data input signal is based on the clock input signal, that is, each clock input signal can only capture a single input data. For an application field where the number of light-emitting diodes is increasing, The speed of inputting data is insufficient, and if the frequency of the clock input signal is increased to increase the amount of input data, the LED driver needs to operate at a high frequency, which is very disadvantageous for the electrical action of the LED driver. Affect the stability of the drive.

Therefore, there is a need for a light-emitting diode driving device which can increase the amount of input data without increasing the clock frequency, and requires only a small number of control signals to solve the disadvantages of the above-mentioned conventional techniques.

The main object of the present invention is to provide a light emitting diode driving device for receiving a clock input signal and a data input signal, generating a plurality of light emitting diode driving signals to drive a plurality of light emitting diode strings, and the present invention The LED driving device comprises a clock inversion unit, a trigger signal generating unit, an internal oscillator, a latch signal generating unit, a shift register unit, a latch register unit, a PWM processing unit, and a light emitting diode a driving unit, wherein the internal oscillator or the external input oscillator generates an oscillating signal, and the trigger signal generating unit generates a trigger signal at a positive edge and/or a negative edge of the clock input signal, and provides a shift register unit to acquire the data input signal And the latch signal generating unit receives the clock input signal and the internal or external oscillating signal, and generates a latch signal, and provides a latch register unit to capture the output signal of the shift register unit, and the PWM processing unit receives the clock Switching the switch signal and passing the output signal of the latch register unit to the PWM processing unit, and then transmitting to the LED driving unit to emit light The diode drive unit drives a string of light-emitting diodes connected to the power source.

The LED driving device of the present invention can be connected in series, and only needs to connect the data output signal and the clock output signal of each LED driving device to the data input signal of the next LED driving device. And the clock input signal, simplifying the circuit board design and increasing the number of series of LEDs, which can be used to increase the number of LED strings without additional control signals, thus simplifying overall system wiring. And reduce system costs while improving system reliability.

The embodiments of the present invention will be described in more detail below with reference to the drawings and the <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt;

Referring to the first figure, a schematic diagram of a light-emitting diode driving device of the present invention. As shown in the first figure, the LED driving device of the present invention receives the clock input signal CKI and the data input signal DI, and generates a plurality of LED driving signals for driving a plurality of LEDs connected to the power supply VDD. The body string 2, and outputs a clock output signal CKO and a data output signal DO, wherein each of the light-emitting diode strings 2 includes a plurality of serially connected light-emitting diodes, and the clock input signal CKI is required for the data input signal DI The fundamental frequency signal.

It should be noted that, in order to facilitate the description of the features of the present invention, the present embodiment is described by using three strings of light-emitting diodes as exemplary examples, but is not intended to limit the scope of the present invention, and thus substantially, the light-emitting diode The number of strings can be any positive integer.

The LED driving device of the present invention includes a clock inversion unit 10, a trigger signal generating unit 20, an internal oscillator 30, a latch signal generating unit 40, a clock switch 50, a shift register unit 60, and The latch register unit 70 and the LED driving unit 90, wherein the clock inverting unit 10 receives the externally input clock input signal CKI, generates a clock output signal CKO, and the trigger signal generating unit 20 receives the clock input signal CKI. And generating a clock trigger signal CKT at the positive edge and/or the negative edge of the clock input signal CKI, as shown by the waveform of the second figure.

The internal oscillator 30 generates an oscillation signal OSC, and the clock switch 50 receives the oscillation signal OSC and the external clock signal CKE, and selects the oscillation signal OSC or the external clock signal CKE as the clock switching switch signal CKS, and the latch signal generating unit The receiving switch switch signal CKS and the clock input signal CKI are received, and after the phase of the clock input signal CKI has not changed and the preset time is exceeded, a latch signal LAT is generated, and the latch signal LAT is a pulse signal.

The shift register unit 60 includes a plurality of shift registers, each shift register can be a D-type flip-flop, and the clock input clk of each shift register receives the clock trigger signal. CKT. The data input terminal D of the first shift register in the shift register receives the data input signal DI, generates an output signal at the data output terminal Q, and transmits to the data input terminal of the next shift register. D, and so on. The data output terminal Q of the last shift register in the shift register generates a data output signal DO.

The shackle register unit 70 includes a plurality of shackle registers, and each shackle register can be a D-type flip flop. The clock input end clk of each shackle register receives the latch signal LAT, and the data input terminal D of the first shackle register in the shackle register is connected to the data of the first shift register The output terminal Q, the data input terminal D of the next latch register in the latch registers is connected to the data output terminal Q of the next shift register, and so on.

The light-emitting diode driving unit 90 is connected to the light-emitting diode strings 2 and the data output terminal Q of each latch register, and drives the light-emitting diode string 2 by the signal of the data output terminal Q. Diode.

Referring to the third and fourth figures, the data input signal waveform diagram of the light-emitting diode driving device of the present invention. As shown in the third and fourth figures, the data input signal DI of the present invention includes a plurality of command bits arranged in sequence and a plurality of driving data. The command bit includes at least a selection bit, and the driving data may be image data or brightness data, wherein the selection bit may be captured at the beginning positive or negative edge of the clock input signal CKI, and the driving data is in the clock. The positive and negative edges of the input signal CKI are taken. It should be noted that the third and fourth figures show the time point of selection of the selected bit by using the starting positive edge T0 as a chronic instance, but the present invention can also use the initial negative of the clock input signal CKI. The edge is taken as a point in time.

The selected bit represents the type of the subsequent driving data. If the selected bit is a high level, the driving data is a plurality of image data. If the selected bit is a low level, the driving data is a plurality of brightness data. It should be noted that it is also possible to select the subsequent driving data as the brightness data, and select the subsequent driving data as the low level, and specify the subsequent driving data as the image data. Each of the driving data is used to drive a corresponding LED string, such as a red LED string, a green LED string, and a blue LED string, and the third and fourth figures The preset time Ta provides a latch signal generating unit 40 for generating a latch signal LAT.

As shown in the third figure, the drive data represents image data, which are red image data (as indicated by component symbols R0, ..., Rn), green image data (such as component symbols G0, ..., Gn), and blue. Image data (as indicated by component symbols B0,...,Bn). Of course, the order of the red image data, the green image data, and the blue image data may be arbitrarily arranged, and the third figure merely shows an exemplary example.

As shown in the fourth figure, the driving data represents the brightness data, which is red brightness data (as indicated by component symbols R0, ..., Rm), green brightness data (such as component symbols G0, ..., Gm), and blue. The luminance data (as indicated by the component symbols B0, ..., Bm), wherein the component symbol x represents redundant data, the light-emitting diode driving device of the present invention will be skipped. Of course, the order of the red brightness data, the green brightness data, and the blue brightness data may be arbitrarily arranged, and the fourth figure merely shows an exemplary example.

Referring to FIG. 5, a schematic diagram of a light emitting diode driving device according to another embodiment of the present invention. As shown in the fifth figure, the LED driving device of the present invention includes a clock inversion unit 10, a trigger signal generating unit 20, an internal oscillator 30, a latch signal generating unit 40, a clock switch 50, and a shift. The register unit 60, the shackle register unit 70, the PWM processing unit 80, and the LED driving unit 90, wherein the other parts except the PWM processing unit 80 are the same as the embodiment of the first figure, and therefore, the same Some will not go into details.

The PWM processing unit 80 is connected to the data output terminal Q of each latch register of the latch register unit 70, and receives the clock switch signal CKS of the clock switch 50 to generate a PWM output signal COUT. The body driving unit 90 receives the PWM output signal COUT to drive the light emitting diodes of the light emitting diode string 2.

Referring to a sixth figure, a waveform diagram of a data input signal of a light-emitting diode driving device according to another embodiment of the present invention. As shown in the sixth figure, the data input signal DI includes a plurality of command bits arranged in sequence and a plurality of driving data. The command bit includes at least one of a selection bit and a polarity bit, and the driving data may be brightness data or image data, wherein the selection bit may be at the beginning positive or negative edge of the clock input signal CKI撷The drive data is taken at the positive and negative edges of the clock input signal CKI. It should be noted that the sixth figure shows the extraction time point of the selection bit by using the initial positive edge T0 as a chronic example, but the present invention can also use the initial negative edge of the clock input signal CKI as the 撷. Take the time.

The command bit retrieved at the beginning or the leading edge of the clock input signal CKI may be a selected bit or a polar bit, which may be determined by system requirements and is not intended to limit the scope of the present invention. The function of selecting a bit is as described above, and the polarity bit is used to specify the output polarity of the PWM output signal COUT of the PWM processing unit. For example, when the polarity bit is a low bit, the PWM output signal COUT is a forward PWM signal, and When the polarity bit is a high bit, the PWM output signal COUT is a negative PWM signal. Of course, the present invention can also be used. When the polarity bit is a low bit, the output polarity of the PWM output signal COUT is negative, and when the polarity bit is a high bit, the output polarity of the PWM output signal COUT is positive.

It should be noted that the sixth figure shows that the selection bit and the polarity bit are respectively taken from the positive and negative edges of the clock input signal CKI, but the present invention can use the adjacent positive edge to select the selected bit and The polarity bits, or adjacent negative edges, may also be used, so the present invention does not limit the timing of the clock input signal CKI for the selection bits and polarity bits.

The LED driving device of the present invention can be connected in series, and only the data output signal DO and the clock output signal CKO of each LED driving device are respectively connected to the data of the next LED driving device. The input signal DI and the clock input signal CKI can be used to increase the number of LED strings without other control signals, thereby simplifying overall system wiring, reducing system cost, and improving system reliability.

The above is only a preferred embodiment for explaining the present invention, and is not intended to limit the present invention in any way, and any modifications or alterations to the present invention made in the spirit of the same invention. All should still be included in the scope of the intention of the present invention.

2. . . Light-emitting diode string

10. . . Clock inversion unit

20. . . Trigger generating unit

30. . . Internal oscillator

40. . . Latch signal generating unit

50. . . Clock switch

60. . . Shift register unit

70. . . Latch lock register unit

80. . . PWM processing unit

90. . . LED driver unit

B0. . . Blue image data or blue brightness data

Bn. . . Blue image data or blue brightness data

CKI. . . Clock input signal

CKO. . . Clock output signal

COUT PWM. . . output signal

DI. . . Data input signal

DO. . . Data output signal

CKE. . . External clock signal

CKT. . . Clock trigger signal

CKS. . . Clock switch signal

G0. . . Green image data or green brightness data

Gn. . . Green image data or green brightness data

LAT. . . Latch signal

OSC. . . Oscillating signal

R0. . . Red image data or red brightness data

Rn. . . Red image data or red brightness data

T0. . . Starting positive or negative margin

Ta. . . Preset time

VDD. . . power supply

The first figure is a schematic diagram of a light-emitting diode driving device of the present invention.

The second figure is a clock waveform diagram of the light-emitting diode driving device of the present invention.

The third figure is a waveform diagram of data input signals of the LED driving device of the present invention.

The fourth figure is a waveform diagram of another data input signal of the LED driving device of the present invention.

FIG. 5 is a schematic diagram of a light emitting diode driving device according to another embodiment of the present invention.

FIG. 6 is a waveform diagram of a data input signal of a light-emitting diode driving device according to another embodiment of the present invention.

2. . . Light-emitting diode string

10. . . Clock inversion unit

20. . . Trigger generating unit

30. . . Internal oscillator

40. . . Latch signal generating unit

50. . . Clock switch

60. . . Shift register unit

70. . . Latch lock register unit

90. . . LED driver unit

CKI. . . Clock input signal

CKO. . . Clock output signal

DI. . . Data input signal

DO. . . Data output signal

CKE. . . External clock signal

CKT. . . Clock trigger signal

CKS. . . Clock switch signal

LAT. . . Latch signal

OSC. . . Oscillating signal

VDD. . . power supply

Claims (12)

An LED driving device receives a clock input signal and a data input signal, and outputs a clock output signal and a data output signal for driving a plurality of LED strings, wherein the LED strings are included a plurality of serially connected LEDs, wherein the clock input signal is a baseband signal required for the data input signal, and the LED driving device comprises: a clock inversion unit that receives the clock input signal, And generating the clock output signal; a trigger signal generating unit, receiving the clock input signal, and generating a clock trigger signal when the positive edge and/or the negative edge of the clock input signal; an internal oscillator generates a An oscillation signal; a clock switch, receiving the oscillation signal and an external clock signal, and selecting the oscillation signal or the external clock signal as a clock switching switch signal; a latch signal generating unit receiving the clock input And the clock and the switch switch signal, and after the phase of the clock input signal has not changed and after a predetermined time exceeds, a latch signal is generated, The latch signal is a pulse signal; a shift register unit includes a plurality of shift registers, and the clock input of the shift register receives the clock trigger signal, and the shift is temporarily A data input end of a first shift register of the register receives the data input signal, and generates an output signal at a data output end of the shift register, the data output of the shift register The end is connected to the data input end of the next shift register, and a data output end of a last shift register in the shift register generates the data output signal; a latch register unit, Included in the latch register, the clock input terminal of the latch register receives the latch signal, and a data input terminal of a first latch register in the latch register is connected The data output end of the first shift register, the data input end of the next latch register in the latch register is connected to the data output end of the next shift register, the plug The data input end of a last latch register in the lock register is connected to the last shift register An output terminal; and a light-emitting diode driving unit connecting the light-emitting diode strings and connecting the data output ends of each latch register to drive the light-emitting diodes of the light-emitting diode strings . The illuminating diode driving device of claim 1, wherein the data input signal comprises a command bit sequentially arranged and a plurality of driving data, the command bit element comprising at least one selecting bit, the selecting The bit line corresponds to a starting positive or negative edge of the clock input signal, and the driving data corresponds to the positive and negative edges of the clock input signal. The illuminating diode driving device of claim 2, wherein if the selecting bit is at a high level, the driving data is a plurality of image data, and if the selecting bit is a low level, The driving data is a plurality of brightness data. The illuminating diode driving device of claim 2, wherein if the selecting bit is a low level, the driving data is a plurality of image data, and if the selecting bit is a high level, The driving data is a plurality of brightness data. The illuminating diode driving device of claim 2, wherein the shift register and the latch register are a D-type flip-flop. An LED driving device receives a clock input signal and a data input signal, and outputs a clock output signal and a data output signal for driving a plurality of LED strings, wherein the LED strings are included a plurality of serially connected LEDs, wherein the clock input signal is a baseband signal required for the data input signal, and the LED driving device comprises: a clock inversion unit that receives the clock input signal, And generating the clock output signal; a trigger signal generating unit, receiving the clock input signal, and generating a clock trigger signal when the positive edge and/or the negative edge of the clock input signal; an internal oscillator generates a An oscillation signal; a clock switch, receiving the oscillation signal and an external clock signal, and selecting the oscillation signal or the external clock signal as a clock switching switch signal; a latch signal generating unit receiving the clock input And the clock and the switch switch signal, and after the phase of the clock input signal has not changed and after a predetermined time exceeds, a latch signal is generated, The latch signal is a pulse signal; a shift register unit includes a plurality of shift registers, and the clock input of the shift register receives the clock trigger signal, and the shift is temporarily A data input end of a first shift register of the register receives the data input signal, and generates an output signal at a data output end of the shift register, the data output of the shift register The end is connected to the data input end of the next shift register, and a data output end of a last shift register in the shift register generates the data output signal; a latch register unit, Included in the latch register, the clock input terminal of the latch register receives the latch signal, and a data input terminal of a first latch register in the latch register is connected The data output end of the first shift register, the data input end of the next latch register in the latch register is connected to the data output end of the next shift register, the plug The data input end of a last latch register in the lock register is connected to the last shift register An output end; a pulse width modulation (PWM) processing unit receives the clock switch signal and connects the data output end of each latch register, and uses the clock switch switch signal to utilize the latch lock a signal at the data output end of the register to generate a PWM output signal; and a light emitting diode driving unit connected to the light emitting diode strings and receiving the PWM output signal to drive the light emitting diode strings The light emitting diode; wherein the shift register and the latch register are a D-type flip-flop. The illuminating diode driving device of claim 6, wherein the data input signal comprises a command bit sequentially arranged and a plurality of driving materials, wherein the command bit includes a selecting bit and a polarity bit. At least one of the elements, the selected bit or polarity bit corresponding to a starting positive or negative edge of the clock input signal, and the driving data corresponding to the positive and negative edges of the clock input signal edge. The illuminating diode driving device of claim 7, wherein if the selecting bit is at a high level, the driving data is a plurality of image data, and if the selecting bit is a low level, The driving data is a plurality of brightness data. The illuminating diode driving device of claim 7, wherein if the selecting bit is a low level, the driving data is a plurality of image data, and if the selecting bit is a high level, The driving data is a plurality of brightness data. According to the illuminating diode driving device of claim 7, wherein if the polarity bit is at a high level, the PWM output signal is a forward PWM signal, and if the polarity bit is a low level, The PWM output signal is a negative PWM signal. According to the light-emitting diode driving device of claim 7, wherein if the polarity bit is a low level, the PWM output signal is a forward PWM signal, and if the polarity bit is a high level, The PWM output signal is a negative PWM signal. The illuminating diode driving device according to claim 6, wherein the shift register and the latch register are a D-type flip-flop.