JP2004361761A - Dynamic driving system for led display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a flicker as well by making it possible to raise the switching frequency which is heretofore limited by an after-image in dynamic driving of LED displays. <P>SOLUTION: Common signals are subjected to the control to provide the signals with a lighting period and a light out period within respective driving periods of respective groups 1 to (n) in dynamic driving of a number of the LED displays L<SB>1</SB>to L<SB>n</SB>. Either of the common signals or the driving output signals or both the signals are also subjected to the control to provide the signals with the lighting period and the light out period and the control of the brightness by varying the ratio of the lighting time/the light out time. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a driving method of an LED display provided in a microcomputer circuit or the like.
[0002]
[Prior art]
In a microcomputer circuit or the like, when an LED display is used and a large number of LED displays are turned on simultaneously, current consumption increases. As a countermeasure against this, conventionally, as shown in FIG. 3A, a circuit configuration in which common terminals E _{1 to} En of a large number of LED displays L _{1 to} L _N are divided into groups _{1 to n} is used. by switching in time a driving output signal and the common signal splitting as shown in b), LED indicator L ₁ ~L _n is lit division when the lighting time of 1 / n times for each group, the lighting all points simultaneously A dynamic driving method is adopted to prevent such a phenomenon (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-9-225091
[Problems to be solved by the invention]
The conventional dynamic driving method is effective for reducing current consumption, but in principle, the LED display is switched on and turned on for each group, so that the lighting time of each group becomes 1 / n, and the group switching is performed. When the frequency is low, the display flickers.
[0005]
When the switching frequency is increased to eliminate the flicker, there is a possibility that an error may occur in discriminating between the light-off state and the light-on state due to an afterimage.
[0006]
An object of the present invention is to provide a dynamic driving method for an LED display which has solved the above-mentioned problems.
[0007]
[Means for Solving the Problems]
According to the present invention, in a dynamic driving method in which a group unit is time-divisionally driven, one or both of a driving output signal and a common signal are turned on and off within a driving period so that an LED display is turned on and off for each group. The driving method has a period and an extinguishing period, and is characterized by the following configuration.
[0008]
(1) When driving a large number of LED displays, drive output signals and common signals applied to each LED display are grouped and connected, and the drive output signals or common signals for each group are switched in a time-division manner. , A dynamic driving method of lighting each LED display in a time-division manner,
One of the common signal and the drive output signal, or both of the signals, includes a drive control unit having a lighting period and a light-off period within the driving period of the group.
[0009]
(2) The drive control means controls the average value of the brightness of each LED display by changing the ratio of the lighting period to the light-off period.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
FIG. 1 shows an LED display circuit and drive signals of the present embodiment. The LED display circuit has a configuration that enables grouped driving as in FIG.
[0011]
The difference from FIG. 3 is the driving pattern. As shown in FIG. 1B, the common signal in each of the groups 1 to n includes the first half of the ON period (the lighting time of the LED display) and the second half of the OFF period. (Time for turning off the LED display).
[0012]
For example, in the driving period of the group 1 of FIG. 1 is to light the LED indicator _L 1 ~L ₃ Group 1 from the timing _{t 1} to _{t 2,} the LED indicator _L 1 ~L ₃ from the timing _{t 2} to _{t 3} Turn off the light.
[0013]
Therefore, in the present embodiment, the LED display of the same group is always turned on within the group drive time, but in the present embodiment, the light-on time and the light-off time are provided within the group drive time.
[0014]
This makes it possible to increase the switching frequency, which was conventionally limited by the afterimage, and suppress flickering. Further, the brightness (average value) can be controlled by changing the ratio of the lighting / light-out time.
[0015]
(Embodiment 2)
FIG. 2 shows this embodiment, and shows only drive signals for the LED display. The difference of this embodiment from FIG. 1 is that the common signal is switched in a time division manner for each of the groups 1 to n, and the group output signal includes the first half of the ON period (LED lighting time) and the second half of the OFF period (LED display). Lighting off time).
[0016]
For example, in the driving period of the group 1 of FIG. 2 is to light the LED indicator _L 1 ~L ₃ Group 1 from the timing _{t 1} to _{t 2,} the LED indicator _L 1 ~L ₃ from the timing _{t 2} to _{t 3} Turn off the light.
[0017]
Also in the present embodiment, as in the first embodiment, by providing the lighting time and the turning-off time within the group driving time, the switching frequency conventionally limited by the afterimage can be increased, and the flicker can be suppressed. Further, the brightness (average value) can be controlled by changing the ratio of the lighting / light-out time.
[0018]
In the above embodiments, the case where the lighting period and the light-off period are provided for one of the drive output signal and the common signal is shown. However, the light-on period and the light-off period are provided at the same timing for both the drive output signal and the common signal. You can also.
[0019]
【The invention's effect】
The conventional dynamic drive system is effective for reducing the current consumption, but in principle has problems of flickering and afterimage because the LED display is switched on and turned on in a short time, but according to the present invention, In order to provide the LED display in one or both of the drive output signal and the common signal in the light-on state and the light-off state for each group, a light-on period and a light-off period are provided within the drive period. The frequency can be increased, and flicker can be suppressed. Further, the brightness can be controlled by changing the ratio of the lighting / light-out time.
[Brief description of the drawings]
FIG. 1 shows an LED display and drive signals according to a first embodiment of the present invention.
FIG. 2 is a driving signal of an LED display according to a second embodiment of the present invention.
FIG. 3 shows a conventional LED display and driving signals.
[Explanation of symbols]
L ₁ ~L _N ... LED display

Claims (2)

To drive a large number of LED displays, connect the drive output signals and common signals applied to each LED display in groups, and switch the drive output signal or common signal for each group in a time-division manner. A dynamic drive system that lights the display in a time-division manner,
Wherein one of the common signal and the drive output signal, or both of the signals, includes a drive control unit having a light-on period and a light-off period within a drive period of the group; method. 2. The dynamic driving method according to claim 1, wherein the driving control unit controls an average value of brightness of each LED display by changing a ratio of the lighting period and the light-off period. 3. .

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