TWI425481B - Light emitting diode driving apparatus - Google Patents

Description

Light-emitting diode driving device

The present invention relates to a driving circuit for a light emitting diode, and more particularly to a driving circuit capable of mode switching by using a data signal and a latch signal or a pin of a data signal and an enable signal.

Light Emitting Diode (LED) is small, power-saving and durable, and as the process matures, the price drops. Recently, products using light-emitting diodes as light sources are becoming more and more popular. In addition, the light-emitting diode has a low working voltage, can actively emit light and has a certain brightness, and the brightness can be adjusted by voltage or current, and has the characteristics of impact resistance, vibration resistance and long life. Therefore, the light-emitting diode is in various terminal devices. Widely used, from automotive headlights, traffic lights, text displays, billboards and large screen video displays, to general and architectural lighting and LCD backlighting.

In the conventional technology, the driving device of the light emitting diode is configured to elastically change operation settings, such as latch signal control, gray scale setting, global brightness control (Global Brightness Control), and single point color adjustment (Dot Correction). ), enable signal control (Enable), image update frequency setting, power saving mode or error detection mode. The drive unit will have multiple sets of control signal pins to allow the user to make adjustments based on different system usage.

However, too many pins can increase the cost of the chip package and the circuit complexity of the printed circuit board, increasing product development time and failure rate.

The invention provides a driving device for a light-emitting diode, which can directly switch the working mode of the driving device by using the waveform composition of the data signal and the latching signal, thereby reducing the number of pins of the driving device, and transmitting the data signal and the latching signal. The pin has a function of mode switching.

The invention provides a driving device for a light emitting diode, which can directly switch the working mode of the driving device by using the waveform composition of the data signal and the enabling signal, thereby reducing the number of pins of the driving device and allowing the data signal and the enabling signal to be transmitted. The pin has a function of mode switching.

In view of the above, the present invention provides a driving device for a light emitting diode, comprising a shift register unit, a latch unit, a driving unit and a mode switching unit. The shift register unit receives a data signal via a first pin, and the latch unit is coupled to the shift register unit and receives a latch signal via a second pin. The driving unit is coupled to the latching unit for driving the display component, and the mode switching unit is coupled to the first pin and the second pin, and switches the working mode of the driving device according to the data signal and the latching signal.

In an embodiment of the invention, when the latch signal is at a certain level, the mode switching unit switches the operating mode of the driving device according to the number of pulses generated by the data signal during the period in which the latch signal is at the specific level.

In an embodiment of the invention, the operating mode of the driving device includes a gray level setting, a display element lighting time control, a display element overall brightness control, a single point color level adjustment, a driving output signal size control, Consistent signal control, an image update reference frequency setting, a drive output signal inversion setting, a drive status detection, a display element status detection, a power saving mode, or an error detection mode.

In an embodiment of the invention, the driving device further includes a third pin, and the shift register unit receives a clock signal via the third pin. When the mode switching unit switches the operating mode of the driving device according to the data signal and the latching signal, the clock signal is disabled.

In an embodiment of the invention, the driving device further includes a multiplexer having two input ends coupled to the output pin of the shift register unit and the first pin for transmitting the data signal. An output end of the multiplexer is coupled to a fourth pin, and a select end of the multiplexer is coupled to the mode switching unit or the latch signal.

The invention further provides a driving device for a light emitting diode, comprising a shift temporary storage unit, a latching unit, a driving unit and a mode switching unit. The shift register unit receives a data signal via a first pin, and the latch unit is coupled to the shift register unit for latching data. The driving unit is coupled to the latching unit and receives the unifying signal via a fifth pin. The mode switching unit is coupled to the first pin and the fifth pin, and switches the operating mode of the driving device according to the data signal and the enabling signal.

Based on the above, the present invention can perform the operation mode switching by combining the data signal with the specific signal (the latch signal or the enable signal), and the driving device can enter different working modes, such as the power saving mode or the error detection mode. Thereby, the number of pins of the driving device can be reduced to reduce the process cost and design complexity.

The above described features and advantages of the present invention will be more apparent from the following description.

First embodiment

Referring to FIG. 1 , FIG. 1 illustrates a driving device for a light emitting diode according to a first embodiment of the present invention. The driving device 100 includes a shift register unit 110 , a latch unit 120 , a driving unit 130 , and a mode switching unit 140 . Worker 150. The shift register unit 110 receives a data signal DAT via a first pin P1 and receives a clock signal CLK via a third pin P3. The latch unit 120 is coupled to the shift register unit 110 and receives a latch signal LAT via the second pin P2. The driving unit 130 is coupled to the latch unit 120 and receives the coincidence signal EN via the fifth pin P5. The mode switching unit 140 is coupled to the first pin P1 and the second pin P2 to receive the data signal DAT and the latch signal LAT. The input end of the multiplexer 150 is coupled to the output signal of the shift register unit 110 and the data signal DAT received by the first pin P1, and the output end of the multiplexer 150 is coupled to the fourth pin P4. The selection end of the device 150 is coupled to the mode switching unit 140, and can be controlled by the mode switching unit 140 or directly controlled by the latch signal LAT.

The shift register unit 110 can store the data signal DAT according to the data clock signal CLK, and the latch unit 120 latches the data output by the shift register unit 110 according to the latch signal LAT. The driving unit 130 determines whether to output a driving signal to drive the connected light emitting diode according to the enable signal EN. The data signal DAT, the latch signal LAT and the clock signal CLK are respectively transmitted to the driving device 100 via different pins. The driving device 100 is, for example, a driving chip, and the fourth pin P4 is an output pin of the driving device 100, and can be used to transmit the data signal DAT to the driving chip of the next stage. This allows multiple drive units to be cascaded to drive the entire LED display.

The mode switching unit 140 is coupled to the first pin P1 and the second pin P2 to receive the data signal DAT and the latch signal LAT, and performs the operation of the driving device 100 by combining the waveform of the data signal DAT and the latch signal LAT. Mode switching. The working mode of the driving device 100 is, for example, a gray scale number setting, a display component lighting time control, a display component overall brightness control, a single dot color gradation adjustment, a driving output signal size control, a uniform energy signal control, and an image. The reference frequency setting, a driving output signal inversion setting, a driving device state detection, a display component state detection, a power saving mode or an error detection mode are updated.

According to different design requirements, the latch unit 120 can be triggered by the rising edge, the falling edge, the high level or the low level of the latching signal LAT to latch the data. When the latch unit 120 is triggered by a rising edge or a falling edge, the mode switching unit 140 may perform mode switching by using a high level or a low level of the latch signal LAT. Taking the high level as an example, when the latch signal LAT is at the specific level (ie, the high level), the mode switching unit 140 generates the signal according to the data signal DAT during the period in which the latch signal LAT is at the specific level. The number of pulses or a combination of their waveforms switches the mode of operation of the drive unit 100. Conversely, the specific level can also be set to a low level. When the mode switching unit 140 detects that the latch signal LAT is at a low level, it will detect the pulse number of the data signal DAT or its waveform combination, and then The operating mode of the drive unit 100 is adjusted. Therefore, the driving device 100 does not need to additionally set the mode switching pin to perform the working mode switching, and the user can directly perform the working mode switching via the first pin P1 and the second pin P2.

Similarly, when the latch unit 120 is in the high level or low level trigger, the mode switching unit 140 can perform mode switching by using the level of the latch signal LAT that is not used for latching. For example, if the latch unit 120 is a high level trigger, the mode switching unit 140 may determine the operating mode of the driving apparatus 100 by using a combination of the low level of the latch signal LAT and the waveform of the data signal DAT. In other words, when the mode switching unit 140 detects that the latch signal LAT is at a certain level of mode switching, the waveform of the data signal DAT is detected, and then the mode of the driving device 100 is switched according to the waveform combination.

The multiplexer 150 has a function of transferring the material signal DAT to the next stage. The multiplexer 150 can be controlled by the mode switching unit 140 or directly controlled by the latch signal LAT. When the mode switching unit 140 performs the mode switching detection, the channel of the multiplexer 150 is switched to the data signal DAT. The drive unit of the next stage can also receive the data signal DAT to switch synchronously. When the shift register unit 110 in the driving device 100 is receiving data, the mode switching unit 140 switches the channel of the multiplexer 150 to the output of the shift register unit 110 so that the driving device of the next stage can receive the shift. The output data of the bit buffer unit 110.

In addition, it is worth noting that the mode switching unit 140 uses the data signal DAT and the latch signal LAT to detect the operating mode that the user needs to set. Therefore, the system can stop inputting the clock signal CLK (that is, disable the clock signal CLK) when the mode switching is to be performed, so that the data error received by the shift register unit 110 can be avoided. In addition, in the present embodiment, the fifth pin P5 in FIG. 1 is not necessary, and the driving unit 130 can also obtain the enable signal EN by other means, for example, according to the latch signal LAT or by the inside of the driving device 100. This embodiment is not limited by the circuit.

Second embodiment

2 is a driving device of a light emitting diode according to a second embodiment of the present invention. The driving device 200 includes a shift register unit 110, a latch unit 120, a driving unit 130, a mode switching unit 140, and a multiplexer 150. The shift register unit 110 receives a data signal DAT via a first pin P1 and receives a clock signal CLK via a third pin P3. The latch unit 120 is coupled to the shift register unit 110 to receive a latch signal to latch the data. The driving unit 130 is coupled to the latch unit 120 and receives the enable signal EN via the fifth pin P5. The main difference between FIG. 2 and FIG. 1 is that the mode switching unit 140 is coupled to the first pin P1 and the fifth pin P5 to receive the data signal DAT and the enable signal EN.

In this embodiment, the enable signal EN is substituted for the latch signal LAT, and the mode switching unit 140 can switch the operating mode of the driving device 200 according to the waveform combination of the data signal DATA of the enable signal EN. Since the enable signal EN is generally used to enable the output of the driving unit 130 to adjust the gray scale of the light emitting diode. Therefore, if the enable signal EN is enabled at the high level to drive the unit 130, the normal operation of the driving unit 130 will not be affected when the enable signal EN is at the low level. The mode switching unit 140 can set the low level of the enable signal EN to a specific level for matching the data signal DAT to generate a mode switching signal for switching the working mode. On the contrary, the mode switching unit 140 can also set the high level of the enable signal EN to a specific level, and cooperate with the data signal DAT to achieve the effect of the operation mode switching.

It can be seen from the above that the fifth pin P5 and the first pin P1 have multiple functions, and can be used not only to transmit the normal enable signal EN and the data signal DAT, but also to switch the operation mode through the waveform combination. Thereby, the number of pins of the driving device 200 can be reduced to reduce design complexity and process cost. In addition, the remaining components and operations in FIG. 2 above are the same as those in FIG. 1, and are not described here. In addition, in the present embodiment, the second pin P2 in FIG. 2 is not necessary, and the latch unit 120 can also obtain the latch signal LAT by other means, for example, according to the enable signal EN or by the driving device 200. The internal circuit is produced, and the embodiment is not limited.

Next, the waveform combination of the latch signal LAT or the enable signal EN and the data signal DAT is further explained. Please refer to FIG. 3 , which illustrates a waveform combination of the latch signal LAT or the enable signal EN and the data signal DAT. First, the high level of the latch signal LAT is taken as a specific level for detecting the mode switching as an example. Referring to FIG. 3(a) and FIG. 3(b), respectively, two different waveform combinations are shown. In FIG. 3(a), the data signal DAT is generated in the period T1 during which the latch signal LAT is at a high potential. Pulses. In Fig. 3(b), the data signal DAT generates four pulses in the period T1. Therefore, the waveform combination of FIG. 3(a) and FIG. 3(b) can correspond to two operating modes, such as a power saving mode and an error detection mode. Similarly, the enable signal EN and the data signal DAT can also generate the same waveform combination for operating mode switching.

3(c) and FIG. 3(d) show the low level of the latch signal LAT as a specific level for detecting mode switching. For example, in FIG. 3(c), the data signal DAT is in the period T2. Three pulses are generated in the middle, and in Fig. 3(d), the data signal DAT generates four pulses in the period T2. Therefore, the waveform combination of FIG. 3(c) and FIG. 3(d) can correspond to two operating modes, such as a power saving mode and an error detection mode. Similarly, the enable signal EN and the data signal DAT can also generate the same waveform combination for operation mode switching, and the signal waveform is as shown in FIG. 3(a) to FIG. 3(b).

In another embodiment of the present invention, the waveform combination of the latch signal LAT and the data signal DAT or the waveform combination of the enable signal EN and the data signal DAT is not limited to FIG. Those skilled in the art will be able to easily infer other waveform combinations after the disclosure of the present invention, and will not be described herein. In addition, it is worth noting that since the present invention uses the first pin P1 of the transfer data signal DAT and the other pin (P2 or P5) to perform the operation mode switching, no data error occurs.

In summary, the present invention uses a pin combination of a transfer data signal and a latch signal or a pin combination of a data signal and an enable signal to switch the operation mode, thereby reducing the connection of the LED driver. The number of feet reduces the design cost and complexity of the drive unit.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

100, 200. . . Drive unit

110. . . Shift register unit

120. . . Latch unit

130. . . Drive unit

140. . . Mode switching unit

150. . . Multiplexer

P1~P5. . . First to fifth pins

DAT. . . Data signal

CLK. . . Clock signal

LAT. . . Latch signal

EN. . . Enable signal

T1, T2. . . Period of specific level

1 is a diagram showing a driving device of a light emitting diode according to a first embodiment of the present invention.

2 is a diagram showing a driving device of a light emitting diode according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram showing the waveform combination of the latch signal LAT or the enable signal EN and the data signal DAT.

100. . . Drive unit

110. . . Shift register unit

120. . . Latch unit

130. . . Drive unit

140. . . Mode switching unit

150. . . Multiplexer

P1~P5. . . Pin

DAT. . . Data signal

CLK. . . Clock signal

LAT. . . Latch signal

EN. . . Enable signal

Claims (11)

A driving device for a light-emitting diode, comprising: a shift temporary storage unit, receiving a data signal via a first pin; a latching unit coupled to the shift register unit and via a second pin Receiving a latching signal; a multiplexer comprising: a first input coupled to an output of the shift register unit; a second input coupled to the first pin to receive the data signal; An output terminal; and a mode switching unit coupled to the first pin and the second pin, and switching an operation mode of the driving device according to the data signal and the latch signal, wherein the mode switching unit is performing When detecting the switching of the working mode, the output of the multiplexer is set to output the data signal of the second input. The driving device of the light-emitting diode according to claim 1, wherein when the latching signal is at a specific level, the mode switching unit is at the specific level according to the data signal. The number of pulses generated during the period switches the operating mode of the drive. The driving device of the light emitting diode according to claim 1, wherein the driving mode of the driving device comprises a gray scale number setting, a display element lighting time control, a display element overall brightness control, and a single point. Level adjustment, one drive output signal size control, uniform signal control, an image update reference frequency setting, a drive output signal reverse setting, a drive status detection, a display element status detection, a power saving mode or An error detection mode. The driving device of the light-emitting diode according to claim 1, wherein the driving device further comprises a third pin, and the shift register unit receives a clock signal via the third pin. The driving device of the light emitting diode of claim 4, wherein the clock signal is disabled when the mode switching unit switches the operating mode of the driving device according to the data signal and the latching signal. A driving device for a light-emitting diode includes: a shift temporary storage unit that receives a data signal via a first pin; a driving unit coupled to a second pin to receive a uniform energy signal; a multiplexer The first input end is coupled to the output of the shift register unit; the second input end is coupled to the first pin to receive the data signal; and an output end; and a mode switching unit, The operating mode of the driving device is switched according to the data signal and the enabling signal, wherein when the mode switching unit detects the working mode switching, the mode is coupled to the first pin and the second pin. The output of the multiplexer is configured to output the data signal of the second input. The driving device of the light emitting diode according to claim 6, wherein when the enabling signal is at a specific level, the mode switching unit is at the specific level according to the data signal. The number of pulses generated during the period switches the operating mode of the drive. The driving device of the light emitting diode according to claim 6, wherein the driving mode of the driving device comprises a gray scale number setting, a display component lighting time control, a display component overall brightness control, and a single point Level adjustment, one drive output signal size control, uniform signal control, an image update reference frequency setting, a drive output signal reverse setting, a drive status detection, a display element status detection, a power saving mode or An error detection mode. The driving device of the light emitting diode according to claim 6, wherein the driving device further comprises a third pin, and the shift register unit receives a clock signal via the third pin. The driving device of the light emitting diode according to claim 9, wherein the clock signal is disabled when the mode switching unit switches the operating mode of the driving device according to the data signal and the enabling signal. The driving device of the light-emitting diode according to the sixth aspect of the invention, wherein the driving device further comprises: a multiplexer having two input ends respectively coupled to the output of the shift register unit and the a first pin, an output end of the multiplexer is coupled to a fourth pin, and a selection of the multiplexer The end is coupled to the mode switching unit.