TWI609602B - Multi-channel light emitting diode drive control device and system - Google Patents

Description

Multi-channel LED driving control device and system

The invention relates to a control device and system, in particular to a multi-channel light-emitting diode drive control device and system.

At present, the common driving method of Light-Emitting Diode (LED) is Pulse Width Modulation (PWM) and Non-PWM Modulation (non-PWM). All of them achieve the brightness of different gray scales by controlling the time of the light-emitting diodes to turn ON (OFF). The ratio of the light-emitting diodes of the former is bright and dark (Duty) is N bits. (bit) grayscale data control, while the latter divides a duty cycle into a plurality of sub-cycles, and then illuminates a fixed time according to different bits.

Referring to FIG. 1, a schematic diagram of a non-pulse width modulation technique (non-PWM) is illustrated by using a 5-bit gray scale data as an example. The non-pulse width modulation technique provides different times by the LED driving circuit. The constant current of the length reaches the light-emitting diode to achieve different gray scale performance. When the light-emitting control signal is low level in FIG. 1 , the light-emitting diode is bright, and when the light level is high, the light-emitting diode is turned off (turn) -off), the interval of the data transmission signal is the time for transmitting each sub-period data.

As can be seen from Fig. 1, in each sub-period, only one of the bits of the grayscale data is displayed, and when the displayed grayscale is low, the time required to transmit the grayscale data (i.e., the interval of the data transmission signal) It will be longer than the time when the LED output circuit outputs a constant current (that is, when the illuminating control signal is at a low level), especially in the industry, a plurality of illuminating diode driving circuits are commonly connected in series and share a data transmission line, so the ash is transmitted. The time required for the order data will be increased upward according to the number of LED driving circuits connected in series, so that the light-emitting time of the light-emitting diode will be lower in the whole working period, and the light-emitting second The closing time of the polar body is higher. On the other hand, when the gray scale displayed is high, as shown in Fig. 1, the fourth bit must use two sub-periods to emit light, but the grayscale data only needs to be After a sub-cycle is completed, the time required for the LED output circuit to output a constant current is greater than the time required to transmit the gray-scale data, resulting in wasted time for transmitting grayscale data.

In this way, the luminous efficiency of the light-emitting diode (Utility, which is related to the proportion of the light-emitting time in the entire working cycle) and the refresh rate (the reciprocal of the cycle time related to the sub-period) are reduced, especially refreshing. The reduced rate will cause the camera to take incomplete pictures (such as black shadows, etc.) when shooting at a higher speed shutter.

Referring to FIG. 2, it is a schematic diagram of a pulse width modulation technique (PWM). The grayscale data of 5 bits is also taken as an example. The pulse width modulation technique is to use all the bits of the grayscale data together in the working cycle. It is shown that when the illumination control signal is at a low level in FIG. 2, the LED is illuminated. When the LED is at a high level, the LED is turned off, and the interval of the data transmission signal is The time at which the grayscale material was transmitted.

As can be seen from Figure 2, the 5-bit grayscale data will be concentrated in 2 ⁰ +2 ¹ +2 ² +2 ³ +2 ⁴ clocks, so that although the problem of luminous efficiency can be improved, Each time the amount of data transmitted is high (5 digits x channel number x number of LED driver circuits connected in series), when the number of LEDs driving in series is large, the amount of data transmitted will be limited. And the situation where the refresh rate is lowered.

3, in order to increase the refresh rate, the industry common practice is to break up the average gray-scale data in a plurality of sub-periods, the gray-scale data 5 yuan to break up the four sub-cycle as an example, its method is to ²⁰ +2 ¹ +2 ² +2 ³ +2 ⁴ illuminating clocks are broken into 4 groups 2 ⁰ +2 ¹ +2 ² clocks plus remainder compensation, also the 2nd in the gray scale data The 4-bit (2 ² +2 ³ +2 ⁴ clocks) is divided into 4 sub-cycles (4*(2 ⁰ +2 ¹ +2 ² ) clocks), and the remaining 0~1 bits (2 ⁰ +2 ¹ clock) and then compensated separately (not shown in Figure 3), the mathematical expression is as follows: 2 ⁰ +2 ¹ +2 ² +2 ³ +2 ⁴ =4*(2 ⁰ +2 ¹ +2 ² )+(2 ⁰ +2 ¹ )

However, although the total illuminating time is constant from the above equation, and the breakout into 4 sub-cycles can increase the refresh rate by about 4 times (4 times the shutter is enough for the camera to not capture black shadows), this method will The amount of data to be transmitted is increased. For example, each channel originally transmits only 5 bits. In this mode, the bits to be transmitted during one working period are increased to: number of sub-cycles x (gray data bits -log ₂ sub-cycle number) + log ₂ sub-cycle number = 4 * (5-log ₂ 4) + log ₂ 4 = 4 * 3 + 2 = 14 bits.

As such, there may still be problems with the amount of data transferred. .

Accordingly, a first object of the present invention is to provide a multi-channel light emitting diode drive control apparatus capable of increasing refresh rate and utilization without significantly increasing transmission data.

Therefore, the multi-channel LED driving control device of the present invention is adapted to output a set of pulse width modulation signals according to an original gray scale data of one N bit to control at least one LED driving circuit to drive the plurality of LEDs Body illuminating, wherein the original gray scale data is scattered in M sub-periods in a working cycle, N and M are positive integers, and the multi-channel LED driving control device comprises a shift register and a buffer , a configuration table register, and a pulse generator.

The shift register is adapted to receive the original gray scale data in series, and in each sub-cycle, receive the K-bit of the original gray-scale data and output the display data as a K-bit, wherein K is less than A positive integer of N.

The buffer receives the display data output by the shift register, and temporarily stores the display data.

The configuration table register is adapted to receive a configuration table data, and temporarily store the configuration table data, and the K-bit associated with the display data is the number of the original gray-scale data respectively. yuan.

The pulse generator receives the display data from the buffer, receives the configuration table data from the configuration table register, and outputs the related pulse width modulation signal according to the display data and the configuration table data.

Accordingly, a second object of the present invention is to provide a multi-channel light emitting diode drive control system.

Therefore, the multi-channel LED driving control system of the present invention comprises a data processing device and a multi-channel LED driving control device.

The data processing device breaks up an N-bit original gray-scale data into M sub-periods in a working cycle, and outputs K-bits and a configuration table data of the original gray-scale data in each sub-period. The K-bit associated with the original gray-scale data transmitted by the configuration table data is the first bit in the original gray-scale data, where N and M are positive integers, and K is a positive integer smaller than N.

The multi-channel LED driving control device receives the original gray scale data and the configuration table data output by the data processing device, and outputs a set of pulse width modulation signals according to the original gray scale data and the configuration table data. The multi-channel LED driving control device includes a shift register, a buffer, and a configuration table register, for controlling the driving of the plurality of LEDs by the at least one LED driving circuit. And a pulse generator.

The shift register is adapted to receive the original gray scale data in series, and in each sub-cycle, receive the K-bit of the original gray-scale data and output the display data as a K-bit, wherein K is less than A positive integer of N.

The buffer receives the display data output by the shift register, and temporarily stores the display data.

The configuration table register is adapted to receive a configuration table data, and temporarily store the configuration table data, and the K-bit associated with the display data is the number of the original gray-scale data respectively. yuan.

The pulse generator receives the display data from the buffer, receives the configuration table data from the configuration table register, and outputs the related pulse width modulation signal according to the display data and the configuration table data.

The invention has the effect of: dispersing the original gray scale data of N bits into M sub-periods in one working cycle, and using the data processing device and the shift register to transmit only in each sub-period The K-bit of the original gray-scale data and the related configuration table data, so that a smaller number of bits can be used to display higher resolution, improve refresh rate and utilization, and save data transmission and transmission. time.

2‧‧‧ data processing device

3‧‧‧Multi-channel LED driving control device

31‧‧‧Shift register

32‧‧‧buffer

33‧‧‧Configuration Table Register

34‧‧‧Pulse generator

Other features and effects of the present invention will be apparent from the following description of the drawings, wherein: FIG. 1 is a schematic diagram of a conventional non-pulse width modulation technique; FIG. 2 is a conventional pulse width modulation technique. 3 is a schematic diagram of a gray scale data breaking technique; FIG. 4 is a block diagram of an embodiment of a multi-channel light emitting diode driving control system of the present invention; FIG. 5 is a schematic diagram illustrating the embodiment One of the duty cycle and the plurality of sub-cycles; and FIG. 6 is a schematic diagram illustrating a pulse width modulation signal of the embodiment.

Referring to FIG. 4, FIG. 5 and FIG. 6, the embodiment of the multi-channel LED driving control system of the present invention comprises a data processing device 2 and a multi-channel LED driving control device 3.

The data processing device 2 breaks up an N-bit original gray-scale data into M sub-periods in one working cycle, and outputs K-bits and a configuration table of the original gray-scale data in each sub-period ( Global_config_table) data, the K-bit associated with the original gray-scale data transmitted by the configuration table data is the first bit in the original gray-scale data, wherein N and M are positive integers, and K is less than N A positive integer and K≦N-log ₂ M.

The original gray level data has a high gray bit group and a low gray bit group. In a working cycle, the data processing device 2 outputs each bit in the high gray bit group at least twice, and outputs Each bit in the low gray bit group is once, and the order in which the bits of the original gray level data are output is irrelevant to the gray order order.

Each sub-period has a display period. Before each display period begins, the data processing device 2 outputs the configuration table data, and in each sub-period, the configuration table data output by the data processing device 2 is related to the previous sub-period. The K bit of the original gray scale data transmitted in the cycle is the first bit in the original gray scale data.

The multi-channel LED driving control device 3 receives the original gray scale data and the configuration table data output by the data processing device 2, and outputs a set of pulse widths according to the original gray scale data and the configuration table data. The modulating signal is adapted to control at least one illuminating diode driving circuit (not shown) to drive the plurality of illuminating diodes (not shown) to emit light.

In the pulse width modulation signal of each sub-period, the period of driving the light-emitting diodes is related to Number of clocks, where k ₀ , k ₁ ... k _{K -1} are the K bits of the original gray scale data transmitted, t ₀ , t ₁ ... t _{K -1} are respectively the configuration table The corresponding value of the K-bit of the original gray-scale data in the data can be seen from FIG. 5, since the K-bits of the original gray-scale data transmitted in each sub-period are not necessarily the same, the display period of each sub-period The times are not necessarily the same, and in the M sub-cycles of one duty cycle, the sum of the number of clocks driving the light-emitting diodes is equal to .

The multi-channel LED driving control device 3 includes a shift register (register-register), a buffer 32 (buffer), a configuration table register 33, and a pulse generator 34 (PWM pulse). Generator).

As can be seen from FIG. 5, each sub-cycle has the display period, a period for transmitting the configuration table data, and a period for transmitting the original gray-scale data. In each sub-cycle, the configuration table data is first transmitted. Then, the original grayscale data received in the previous sub-period is displayed, and at the same time, the original grayscale data required for the next sub-cycle is transmitted.

The shift register 31 receives the original gray scale data in series by the data processing device 2, and receives the K bits of the original gray scale data in each sub-period and outputs the display data as one K-bit.

The buffer 32 receives the output output by the shift register 31 Display data, output after temporary storage.

The configuration table register 33 receives the configuration table data from the data processing device 2, and before the display period of each sub-cycle begins, the configuration table register 33 receives the new configuration table data, and outputs the data after the temporary storage. To the pulse generator 34.

The pulse generator 34 receives the display data from the buffer 32, receives the configuration table data from the configuration table register 33, and outputs the associated pulse width modulation signal according to the display data and the configuration table data.

As shown in Fig. 6, taking the original gray scale data of 5 bits (ie, N=5) and breaking up into 4 sub-cycles (ie, M=4) as an example, it is worth mentioning that the original gray scale described below The method of uneven distribution of data is only one of them, and is not limited to this.

Since K≦N-log ₂ M=5-log ₂ 4=3, the K value can be a positive integer of 1~3, with K=2 (ie receiving 2 bits per sub-period) as an illustration, 4 sub-periods The way of allocating the clock is expressed as follows. The five bits of the original grayscale data are represented as n ₀ ~ n ₄ :

The first sub-period: n ₀ . 2 ⁰ + n ₃ . 2 ³ =9 (the 0th and 3rd bits of the original grayscale data)

The second sub-period: n ₁ . 2 ¹ + n ₂ . 2 ² = 6 (the first and second bits of the original grayscale data)

The third sub-period: n ₄ . 2 ² + n ₄ . 2 ² = 8 (part of the 4th bit of the original grayscale data)

The fourth sub-period: n ₄ . 2 ² + n ₄ . 2 ² = 8 (part of the 4th bit of the original grayscale data)

Wherein, in this example, the 4th bit of the original grayscale data is divided into the high gray bit group, and the 4th bit is repeatedly transmitted in the 3rd and 4th sub-cycles to achieve the required clock number, and The 0th to 3th bits of the original grayscale data are assigned to the low gray bit group, and the 0th to 3rd bits are transmitted only once in one working cycle. In this example, the original grayscale data is The 4-bit (high-gray byte) is concentrated in the 3rd and 4th sub-cycles, but the clock of the 4th bit (high-gray byte) of the original grayscale data can also be spread out on average. The transmission within the period is not limited to this example.

Taking the first sub-period as an explanation, before the start of the sub-period, the shift register 31 first receives the 2-bit {0th bit, the 3rd bit} of the original gray-scale data and outputs it as The 2-bit display data (assuming the value of the displayed data is {1, 1}), after the start of the sub-period, the configuration table register 33 receives the new configuration table data, and outputs the data to the temporary storage table. The pulse generator 34, in the configuration table data, the corresponding value of the display data will be {0, 3}, and the bit corresponding to the display data is the 0th and 3rd bits in the original grayscale data respectively. Then, the pulse generator 34 generates the pulse width modulation signal according to the display data {1, 1} and the configuration table data {0, 3}, that is, the illumination control signal as shown in FIG. 6 is generated, wherein When the illuminating control signal is at a low level, the illuminating diode is illuminated. When the illuminating control signal is at a low level, the illuminating diode is turned off, and the interval of transmitting the signal is a data time for transmitting each sub-period. The illumination time of the first sub-period is 1*2 ⁰ +1*2 ³ = 9 clocks.

The next sub-period operates in a similar manner to the above, so it will not be described again. The original grayscale data of the 5-bit shown in Fig. 6 is {1, 1, 1, 1, 1}.

In this way, the amount of data to be transmitted during the entire work cycle is only 8 bits. Compared with the conventional gray-scale data scattering technology, not only the refresh rate is increased by about 4 times, but also the amount of data transmitted is 14 bits. The reduction is nearly half, and since the sum of the number of clocks of the light-emitting diodes does not change (as shown in the following equation), gray-scale distortion is not caused.

2 ⁰ +2 ¹ +2 ² +2 ³ +4*(2 ² )=2 ⁰ +2 ¹ +2 ² +2 ³ +2 ⁴

The following is another way of uneven scattering of the original grayscale data, and is not limited thereto.

The high gray byte has a high bit group and a middle bit group, each bit in the high bit group appears once in each sub-period of a work cycle, and each bit in the middle bit group Appear at least twice in one work cycle.

In each sub-period, the number of clocks allocated to each higher gray bit is at least twice the number of clocks allocated to the bits of the second gray, and the corresponding light of each bit in the high-order group The number of clocks is evenly distributed for each sub-period of a duty cycle.

Taking 12-bit original gray-scale data (ie, N=12) and breaking up into 4 sub-cycles (ie, M=4) as an example, since K≦N-log ₂ M=12-log ₂ 4=10, The value of K can be a positive integer from 1 to 10, with K=7 (ie, 7 bits per sub-period) as an illustration. The way of allocating clocks to four sub-periods is mathematically represented as follows, 12 bits of the original grayscale data. The yuan is expressed as n ₀ ~ n _{11 respectively} :

The first sub-period: n ₇ . 2 ⁶ + n ₉ . 2 ⁷ + n ₁₀ . 2 ⁸ + n ₁₁ . 2 ⁹ + n ₈ . 2 ⁶ + n ₃ . 2 ³ + n ₆ . 2 ⁵

The second sub-period: n ₄ . 2 ⁴ + n ₉ . 2 ⁷ + n ₁₀ . 2 ⁸ + n ₁₁ . 2 ⁹ + n ₈ . 2 ⁶ + n ₅ . 2 ⁴ + n ₀ . 2 ⁰

The third sub-period: n ₇ . 2 ⁶ + n ₉ . 2 ⁷ + n ₁₀ . 2 ⁸ + n ₁₁ . 2 ⁹ + n ₈ . 2 ⁶ + n ₁ . 2 ¹ + n ₆ . 2 ⁵

The fourth sub-period: n ₂ . 2 ² + n ₉ . 2 ⁷ + n ₁₀ . 2 ⁸ + n ₁₁ . 2 ⁹ + n ₈ . 2 ⁶ + n ₅ . 2 ⁴ + n _x . 0

Where n _x is an invalid bit, which is only used to fill the gap. In this example, the high gray bit is the 5th to 11th bits of the original gray scale data, and the high bit group is the original gray scale data. The 8th to 11th bits, the median group is the 5th to 7th bits of the original grayscale data, and the low gray bit is the 0th to the 4th of the original grayscale data, so that it can be in each sub When the cycle only transmits 7 bits, it provides 12-bit grayscale resolution, and improves the refresh rate by nearly 4 times without significantly increasing the amount of data transmission (compared with the pulse width modulation technique of Figure 2). ).

Through the above description, the advantages of the embodiment can be summarized as follows: by breaking the original gray scale data of N bits into M sub-periods in one work cycle, and matching the data processing device and the shift temporary The memory transmits only the K bits of the original grayscale data and the associated configuration table data in each sub-cycle, so that a smaller number of bits can be used to display a higher resolution and improve the refresh rate and utilization. Rate, and compared with the prior art, in the case of the same refresh rate, the data transmission amount and transmission time can be greatly saved.

In summary, the object of the present invention can be achieved.

However, the above is only an embodiment of the present invention, when The scope of the present invention is not limited thereto, that is, the simple equivalent changes and modifications made by the present invention in the scope of the invention and the patent specification are still within the scope of the invention.

2‧‧‧ data processing device

3‧‧‧Multi-channel LED driving control device

31‧‧‧Shift register

32‧‧‧buffer

33‧‧‧Configuration Table Register

34‧‧‧Pulse generator

Claims (14)

A multi-channel LED driving control device is configured to output a set of pulse width modulation signals according to an N-bit original gray-scale data, to control at least one LED driving circuit to drive the plurality of LEDs to emit light, Wherein, the original gray scale data is scattered in M sub-periods in a working cycle, and N and M are positive integers. The multi-channel LED driving control device comprises: a shift register, suitable for serializing Receiving the original gray scale data, in each sub-period, receiving the K-bit of the original gray-scale data and outputting the display data as a K-bit, wherein K is a positive integer smaller than N; a buffer, receiving The display data outputted by the shift register is temporarily stored and outputted; a configuration table register is adapted to receive a configuration table data, and temporarily store the configuration table data, and the configuration table data is related to The K bit of the display data is the first bit in the original gray scale data; and a pulse generator, the display data is received by the buffer, and the configuration table data is received by the configuration table register, and According to the Illustrates the configuration table data and outputs the information related to the pulse width modulation signal. The multi-channel LED driving control device according to claim 1, wherein in the pulse width modulation signal of each sub-period, a period of driving the LEDs is related to Number of clocks, where k ₀ , k ₁ ... k _{K -1} are the display data of K bits, and t ₀ , t ₁ ... t _{K -1} are respectively K bits in the configuration table data The corresponding value of the displayed data. The multi-channel LED driving control device according to claim 2, wherein the sum of the number of clocks for driving the light-emitting diodes is equal to M sub-cycles of one duty cycle . The multi-channel LED driving control device of claim 1, wherein the original gray scale data has a high gray bit group and a low gray bit group, in one working cycle: the high gray bit element Each bit in the group is received at least twice by the shift register, each bit in the low gray bit is received by the shift register once, and the bit of the original gray level data is received The order is not related to its grayscale order. The multi-channel LED driving control device of claim 4, wherein, in one sub-period: a portion of the high gray bit group is received by the shift register at least twice, and the original The order in which the bits of the grayscale data are received is not related to the grayscale order. The multi-channel light emitting diode driving control device according to claim 1, wherein: K≦N-log ₂ M. The multi-channel LED driving control device of claim 1, wherein each sub-period has a display period, and the configuration table register receives the new configuration table data before each display period begins, and Output to the pulse generator after temporary storage. A multi-channel LED driving control system comprises: a data processing device, dispersing an N-bit original gray-scale data into M sub-periods in a working cycle, and outputting the original in each sub-period The K-bit of the gray-scale data and a configuration table data, the configuration table data is related to the K-bit of the original gray-scale data transmitted The first bit in the original gray scale data, wherein N and M are positive integers, K is a positive integer less than N; and a multi-channel LED driving control device is received by the data processing device Outputting the original gray scale data and the configuration table data, and outputting a set of pulse width modulation signals according to the original gray scale data and the configuration table data, so as to be suitable for controlling at least one light emitting diode driving circuit to drive the plurality of light emitting lights The multi-channel LED driving control device comprises: a shift register adapted to receive the original gray scale data in series, and receive the K bit of the original gray scale data in each sub-period The output is a K-bit display data, where K is a positive integer less than N; a buffer receives the display data output by the shift register, and temporarily stores the output; a configuration table is temporarily stored The device is adapted to receive a configuration table data, and temporarily output the configuration table data, wherein the K-bit associated with the display data is the first bit of the original gray-scale data; and Pulse generator The buffer receives the data of the display, receives the data from the configuration table the configuration table registers, and according to the display data configuration table, and the information related to the output of the pulse width modulation signal. The multi-channel LED driving control system of claim 8, wherein in the pulse width modulation signal of each sub-period, the period of driving the LEDs is related to Number of clocks, where k ₀ , k ₁ ... k _{K -1} are the K bits of the original gray scale data transmitted, t ₀ , t ₁ ... t _{K -1} are respectively the configuration table Corresponding value of the K bit of the original gray scale data in the data; in the M sub-cycles of one working cycle, the sum of the number of clocks driving the light emitting diodes is equal to . The multi-channel LED driving control system of claim 9, wherein the original grayscale data has a high gray bit group and a low gray bit group, and the data processing device outputs in one working cycle. Each bit in the high gray bit group is outputted at least twice, and each bit in the low gray bit group is outputted once, and the order in which the bits of the original gray level data are output is not related to the gray order order. The multi-channel LED driving control system of claim 10, wherein the high gray bit group has a high bit group and a median group, each bit in the high bit group is in one duty cycle Appears once in each sub-cycle, and each bit in the median group appears at least twice in one work cycle. The multi-channel LED driving control system according to claim 11, wherein in each sub-period, the number of clocks allocated to each of the higher gray bits is the number of clocks allocated to the bits of the second gray At least twice, and the number of illumination clocks corresponding to each bit in the high-order group is equally distributed in each sub-period of one duty cycle. The multi-channel light emitting diode drive control system of claim 9, wherein: K≦N-log ₂ M. The multi-channel LED driving control system of claim 9, wherein each sub-period has a display period, and before the start of each display period, the data processing device outputs the configuration table data, and each sub-period The K-bits of the configuration table data output by the data processing device related to the original gray-scale data transmitted in the previous sub-period are respectively the first bit in the original gray-scale data.