HK1038979A1

HK1038979A1 - A low power led driving apparatus

Info

Publication number: HK1038979A1
Application number: HK02100515A
Authority: HK
Inventors: 贺伟
Original assignee: 贺伟
Priority date: 2001-03-09
Filing date: 2002-01-23
Publication date: 2002-04-04
Also published as: HK1038979B; CN1141691C; CN1319827A

Abstract

The present invention discloses a LED display device with low electric consumption, and is characterized by that all the row and matrix drive wires of LED which are connected in array mode are respectively connected with output interface of microprocessor, and a power supply is connected with the microprocessor, said microprocessor delivers a low level to N pole of some LED, at the same time delivers pulse current to its P pole or delivers a high level to P pole of some LED, at the same time delivers high-low alternated level to its N pole. When the pulse current is flowed to N pole for P pole, it can make LED quickly flash so as to attain the goal of saving electricity. It is high in integrality, small in volume, can be used in watch products and other display with LED.

Description

Low-power-consumption LED display device

The invention relates to a low-power-consumption LED display device.

When the LED (light emitting diode) digital display electronic watch was popular in the early 70 s, the general battery life was only 1-2 months due to the large amount of electricity required to drive the LED to emit light, so that the LCD (liquid crystal display) technology replaced the position of the LED in the electronic watch by its low power consumption characteristic in the middle 70 s. However, the LCD only displays gray black, and the color is monotonous; LCDs can also only use EL (electroluminescence) as a backlight, and LEDs emit light much more than EL and have a variety of colors, such as red, yellow, blue, orange, green, white, etc., available for selection. Therefore, the LED display can be used in the daytime and at night and has good appearance. The LED digital display watches disclosed in US 393939640 and US4033108 have a prolonged battery life by turning on the power supply and the LEDs when in use, and automatically turning off the power supply when not in use, or automatically turning off the system after the power supply is turned on for several seconds to save power.

The invention provides a low power consumption LED display device which has low power consumption and small volume and can inhibit the LED from aging.

The main technical scheme of the invention is as follows: the LEDs are connected in a column mode, the N pole of each LED is connected with a column driving line, the P pole of each LED is connected with a row driving line, each column driving line and each row driving line are respectively connected with a corresponding output port on the microprocessor, a power supply is connected with the microprocessor, and in an initial state, the microprocessor writes '1' into the output port connected with each column driving line, so that the output port, the column driving lines and the N poles of the LEDs are at high level; and writing '0' into the output port connected with each row drive wire, so that the output port, the row drive wire and the P poles of the LEDs are at a low level, and at the moment, each LED does not emit light.

Or the LEDs are connected in a column mode, the N pole of each LED is connected with a column driving line, the P pole of each LED is connected with a row driving line, each column driving line and each row driving line are respectively connected with a corresponding output port on the microprocessor, a power supply is connected with the microprocessor, and in an initial state, the microprocessor writes '1' into the output port connected with each column driving line, so that the output port, the column driving lines and the N poles of the LEDs are at high level; and writing '0' into the output port connected with each driving line, so that the output port, each driving line and the P pole of each LED are at a low level, and at the moment, each LED does not emit light, in the working state, the microprocessor writes '1' into the input port connected with a certain driving line to generate a high level, and outputs a level with alternating high and low levels to the N pole of the LED through a certain driving line, and the LED is arranged corresponding to the row and the column.

The invention adopts array connection, drives more LEDs by the least driving wires, improves the system integration level and reduces the volume. In addition, in the invention, a certain LED is driven to flicker and emit light by the pulse current in one working cycle, and the pulse current supplies power to the LED intermittently, so that the power consumption is reduced on one hand, and the phenomenon of premature aging of the LED under long-time heavy current driving can be avoided on the other hand. The invention can divide the time of producing persistence of vision into a plurality of time slots, and make a plurality of LEDs finish a work cycle in the respective corresponding time slot, thus a plurality of LEDs continuously and circularly flash at high speed, the naked eye sees a picture continuously displayed by a plurality of LEDs, and actually, the picture is equal to that only one LED emits light and consumes power, thereby fundamentally solving the problem of large power consumption when a plurality of LEDs are simultaneously displayed.

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a flowchart illustrating microprocessor control according to a first embodiment of the present invention;

FIG. 3 is a timing diagram of the driving LEDs at the output port of the microprocessor for 20 minutes and 9 seconds at time 2 according to one embodiment;

FIG. 4 is a flowchart illustrating a microprocessor control method according to a second embodiment of the present invention;

FIG. 5 is a timing chart of the driving LEDs at the output port of the microprocessor for 20 minutes and 9 seconds at the time 2 in the second embodiment.

The first embodiment is as follows:

as shown in fig. 1, this embodiment is an LED display device for a timepiece, in which 5 × 30 LEDs are connected in an array, and there are 5 row driving lines P3, P4, P5, P6, P7, and 30 column driving lines C1 to C30, among the LEDs, numbers H1 to H12 correspond to hours, numbers M1 to M60 correspond to minutes, and numbers S1 to S60 correspond to seconds. The P poles of the LEDs with the numbers of S1 to S60 are sequentially connected to the driving lines of the P7 and the P6 rows, and the N poles are respectively connected with the driving lines of the columns of C1 to C30; the P poles of the LEDs numbered from M1 to M60 are sequentially connected to the driving lines of the P5 and the P4 rows, and the N poles of the LEDs are respectively connected with the driving lines of the columns from C1 to C30; the P poles of the LEDs numbered from H1 to H12 are connected with a P3 row driving line, the N pole of the LED H1 is connected with a C5 column driving line, the N pole of the LED H2 is connected with a C10 column driving line, the N pole of the LED H3 is connected with a C15 column driving line, the N pole of the LED H4 is connected with a C20 column driving line, the N pole of the LED H5 is connected with a C25 column driving line, the N pole of the LED H6 is connected with a C30 column driving line, the N poles of the LEDs H7, H8, H9, H10, H11 and H12 are connected with C26, C21, C16, C11, C6 and C1 column driving lines respectively, and the other 18 LEDs are reserved. The driving lines of each row and each column are respectively connected with corresponding output ports on the microprocessor, and a power supply is connected with the microprocessor.

As shown in fig. 2, the microprocessor controls the light emission of the LED according to the following process:

one) in the initial state, the microprocessor writes "1" to the microprocessor output ports connected to the driving lines C1 to C30, making the output ports high, and simultaneously the N poles of all the LEDs connected to the column driving lines C1 to C30 in the LED display array are high at the same time, and the row driving lines P3, P4, P5, P6, and P7 are low, and at this time, the LEDs are at reverse voltage, and the LEDs do not emit light.

And II) writing '0' into the output port of the microprocessor connected with the N pole of the LED needing to emit light by the microprocessor, so that the N pole of the LED is at a low level.

And thirdly) outputting pulse current with Tp as a period to the P pole of the LED, namely writing '1' into the output port of the microprocessor connected with the P pole of the LED.

Four) when the P electrode of the LED is at high level, the LED emits light and the duration is Pw.

And fifthly) writing '0' into the output of the microprocessor connected with the P pole of the LED.

And sixthly) when the P electrode of the LED is at a low level, the LED does not emit light, and the Pt is delayed.

Seventhly), judging whether the LED lighting operation is finished or not, and if so, entering the next step; if not, returning to the third) step.

Eight) the output port of the microprocessor connected with the N pole of the LED is connected with a 1, so that the N pole of the LED is at a high level, and the P pole of the LED is at a low level.

Nine) judging whether LEDs are required to emit light for display. If yes, returning to the second) step; if not, the next step is carried out.

Ten) judging whether the circular display is finished or not, and if not, returning to the second) step; if yes, the process is ended.

FIG. 3 shows an example of displaying time 2 hours, 20 minutes and 9 seconds, and since time, minutes and seconds are displayed simultaneously, the microprocessor divides the time Tc for creating persistence of vision into three time segments T₁、T₂、T₃. The microprocessor writes "1" to the output ports connected to the column driving lines C1 to C30 to put the N poles of all the LEDs in a high state, and writes "0" to the output ports P3, P4, P5, P6, and P7 connected to the row driving lines to put the P poles of all the LEDs in a low state. In a time period T₁Writing '0' into the output port C9 of the microprocessor connected with the N pole of the LED S9 representing 9 seconds, enabling the N pole of the LED S9 to be at a low level, simultaneously outputting pulses at the output port P7, generating m pulse currents with Tp as a period at the P pole of the LED S9, enabling the P pole to be at a high level in time Pw, and enabling the LED S9 to emit light; at time Pt, since the pin is at a low level and the LED does not emit light, the LED S9 is blinking. After the completion of the lighting of the LED S9, at the end of the time period T1, "1" is written to the output port C9, so that the N-pole of the LED S9 returns to the high level, and the LED stops lighting. In the time period T2, the microprocessor writes "0" to the output port C20 connected to the N pole of the LED M20 representing 20 minutes, and outputs a pulse to the output port P5 while making the N pole of the LED M20 low, and M pulse currents with a period of Tp are generated also to the P pole of the LED, thereby lighting the LED. Simultaneously in the time period T₂After that, 1 is written to the output port C20, and N of M20 is set to a high level, so that the LED M20 stops emitting light. In a time period T₃In the microprocessor output port C10 connected to the N pole of the LED H2 representing the 2 state is written with "0", so that the N pole of the LED H2 is at a low level, and at the same time, a pulse is output from the output port P3, and m pulse currents with a period of Tp are generated at the P pole of the LED H2, and the LED emits light. After the light emission of the LEDH2 is completed, "1" needs to be written to the output port C10, so that the N of the LEDH2 is at a high level, and the LED H2 stops emitting light. This completes the operation of the light emitting display of the LEDs S9, M20, H2, i.e., 20 minutes and 9 seconds representing the time point 2, and then repeats the above operation within 1 second. Although the LED emits light in a time-sharing and flickering mode, the LED emits light at a high speed and cannot be distinguished by naked eyes, and therefore the LED looks continuousAnd continuously displaying the picture. And in fact for the whole time equals to only one LED continuously consuming power. If the time reaches 2 hours, 20 minutes and 10 seconds, the LED emitting light in the time period T1 is changed to the LED S10 connected between the row driving line P7 and the column driving line C10, and the above-described operation cycle is repeated.

Example two:

the structure of the present embodiment is the same as that of the first embodiment. As shown in fig. 4, the control flow of the microprocessor is as follows:

one) in the initial state, the microprocessor writes a "1" to the microprocessor output port connected to the column drive lines C1 to C30, causing the output port to be high, while the N-poles of all LEDs connected to the column drive lines C1 to C30 in the display array are also high at the same time, and the row drive lines P3, P4, P5, P6, P7 are low. The LED does not emit light.

And II) writing '1' into the output port of the microprocessor connected with the P pole of the LED needing to emit light by the microprocessor, so that the P pole of the LED is at a high level.

And thirdly) outputting a level which is alternately high and low with Tp as a period to the N pole of the LED, namely writing '0' into the output port of the microprocessor connected with the N pole of the LED.

Four) when the N pole of the LED is at low level, the LED emits light and the holding time is Pw.

And fifthly) writing '1' into the output port of the microprocessor connected with the LEDN pole.

And sixthly) at the N pole of the LED, the LED does not emit light, and the Pt is delayed.

Fig. 5 also shows an example of 20 minutes and 9 seconds when the display time 2 is taken, and other parts thereof are the same as those of the example shown in fig. 3. Only the microprocessor being in the time period T₁、T₂、T₃The control modes in the system are different. In the time period T1, the microprocessor writes "1" to the output port P7 connected to the P pole of the LED SP representing 9 seconds, and makes the P pole of the LED S9 high. Meanwhile, the output port C9 outputs high and low levels, m levels with the period Tp as the period of high and low are generated on the N pole of the LED S9, the N pole is at the low level in the time Pw, the LED S9 emits light, and the N pole is at the high level in the time Pt, and the LED does not emit light. After T1 is completed, the N-pole of LED S9 is returned to the high level state, and the emission of the LED is stopped. In a time period T₂In the microprocessor, the microprocessor writes "1" to the output port P5 connected to the P pole of the LED M20 representing 20 minutes, and makes the P pole of the LED 20 high. At the same time, the output port C20 outputs high and low levels, and m levels with the period Tp as the period alternating high and low are generated at the N pole of the LED. LED M20 operates in the same manner as LED S9. In a time period T₃In the microprocessor, the microprocessor writes "1" to the output port P3 connected to the P pole of the LED H2 representing 2, and outputs a high/low level to the output port C10 while the P pole of the LED H2 is at a high level, and m levels of alternating Tp high/low periods are generated at the N pole of the LED H2. The LED H2 also operates in the same manner as LED S9. The above operation is repeated within 1 second until 2 hours, 20 minutes and 10 seconds are entered.

The invention can adjust the time period T₁、T₂、T₃… … Tn, Pw, Pt and Tp to adjust the brightness of the LED. The longer the Pw time, the shorter the Pt time, and the brighter the LED.

Claims

1. A low power consumption LED display device, characterized in that: the LEDs are connected in a column mode, the N pole of each LED is connected with a column driving line, the P pole of each LED is connected with a row driving line, each column driving line and each row driving line are respectively connected with a corresponding output port on the microprocessor, a power supply is connected with the microprocessor, and in an initial state, the microprocessor writes '1' into the output port connected with each column driving line, so that the output port, the column driving lines and the N poles of the LEDs are at high level; and writing '0' into the output port connected with each row drive wire, so that the output port, the row drive wire and the P poles of the LEDs are at a low level, and at the moment, each LED does not emit light.

2. A low power consumption LED display device, characterized in that: the LEDs are connected in a column mode, the N pole of each LED is connected with a column driving line, the P pole of each LED is connected with a row driving line, each column driving line and each row driving line are respectively connected with a corresponding output port on the microprocessor, a power supply is connected with the microprocessor, and in an initial state, the microprocessor writes '1' into the output port connected with each column driving line, so that the output port, the column driving lines and the N poles of the LEDs are at high level; and writing '0' into the output port connected with each driving line, so that the output port, each driving line and the P pole of each LED are at a low level, and at the moment, each LED does not emit light, in the working state, the microprocessor writes '1' into the input port connected with a certain driving line to generate a high level, and outputs a level with alternating high and low levels to the N pole of the LED through a certain driving line, and the LED is arranged corresponding to the row and the column.

3. A low power consumption LED display device as claimed in claim 1 or 2, wherein: the microprocessor divides the number of LEDs capable of generating persistence of vision Tc into time periods T according to the requirement₁、T₂… … Tn, the microprocessor causes the LEDs to complete a cycle of operation in sequence within respective time periods.