JPS6029894A - Led driving circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an LFiD drive circuit, and more particularly to an EID drive circuit that uses a D flip-flop and a delay circuit and uses the delay time of the delay circuit as the lighting cycle time of the LBD.

Conventionally, this type of LED drive circuit has a static drive method and a dynamic drive method, and the static drive method is L.
I don't particularly feel safe about ED infection.

The disadvantage is that the power consumption is higher than that of the dynamic drive method, although the dynamic drive method can consume less power than the static drive method.

There is a drawback that the LED may be damaged depending on the state of the drive circuit input signal.

The present invention solves the above drawbacks by controlling the lighting time of the LED so that it becomes the delay time of a delay circuit triggered by current flowing through the LED, and separating one lighting time from the input signal, thereby improving the operation of the input side. An object of the present invention is to provide an LBD drive circuit that can prevent damage to LEDs due to stoppage.

Describing the configuration of the present invention, 1. the present invention has an L terminal connected to the D terminal.
Trunk 2 is connected to the D flip-flop to which the ED lighting request signal is input and the LIDD lighting cycle timing signal is input to the C terminal, and the Q output of this D knob 70.
, and the LBD lights up due to the conduction of this transistor.
and a delay circuit which inputs the output of the transistor and inputs the output generated after a certain time delay to the R terminal of the D flip-flop.

According to the present invention, by having the above-mentioned configuration, LI1
Even if the 3D lighting request signal and the LED lighting cycle timing signal stop under any condition, the LED can be protected from being damaged.

The present invention will be explained below by way of examples with reference to the drawings.

FIG. 1 shows a circuit diagram of an embodiment of the present invention, and FIG. 2 shows its operating waveform diagram.

In Figure 1, 1 is a D71J block flop, 2 is a transistor, 3 is an LED, and 4 is a delay circuit.
A is a lighting non-compensation number, CYCIJ is 1. lliD lighting cycle timing signal.

Now, as shown in Figure 2, DATA has the logical value l1l (
When CYCI, E rises from 01 to "11" when LBD is turned on), D flip 70 knob 1 outputs 11 to output Q, turns on transistor 2, and current flows through l and EliD3.%1JD3 lights up. Delay circuit 4 is LED
The presence or absence of current is determined by flZlO'', Th,
Since the output generated after a certain period of time td is input to the reset terminal R of the D flip-flop 70, the Q output of the D flip-flop 1 is 101, and the transistor 2
Becomes depressed. Therefore, LBD3 is set for a certain period of time t after the D flip-flop is set at the rising edge of CYCLE.
Since it remains lit until it is reset by the output of the delay circuit 4 after d has elapsed, no matter what state the input signals of DATA, CYCI, and E stop, the (L
It is possible to protect against BD-z damage.

As explained above, according to the present invention, the lighting time of the IJD is controlled by the delay time of the delay circuit whose input is the presence or absence of current flowing through the FliD. LED for stoppage in any condition
Current flows continuously through 1. [This has a great effect in preventing the trouble of damaging the BD.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is an operational waveform diagram of the circuit shown in FIG. 1...D flip 70 tube, 2...transistor, 3...LII), 4...delay circuit, DATA...1.1 lights up Yasu Hakugo,
CYCIJ...LED lighting cycle timing signal, td...Delay time. Foil/Figure (F input) No.? Illustration procedure amendment 86o. 58 years t! N'A12% F3 Mr. Commissioner of the Japan Patent Office 1, Indication of the case Patent Application No. 138797 of 1982, 2 Name of the invention LED drive circuit 3 Person making the amendment Relationship to the case Patent applicant 33 Shiba 5-chome, Minato-ku, Tokyo No. 1 (423) NEC Corporation Representative Tadahiro Sekimoto 4 Agent No. 6-101Q, Kamiikedai 4-chome, Ota-ku, Tokyo. Detailed Description of the Invention in the Specification and Figure 1 in the Drawings 7 Contents of Amendment (1) Regarding 1 in Section 1, Line 17 of the Specification. ” is related to 1. ” is corrected. (2) Figure 1 of the drawings is corrected to match the attached drawings. Agent Patent Attorney Kuri 1) Yu Haru

Claims (1)

[Claims] An LED lighting request signal is input to the C terminal, and an LED lighting request signal is input to the C terminal.
A D-flip 70 block to which the lighting cycle timing signal is input, a transistor that is turned on by the Q output of this D7-lip 70 block, an LED that lights up due to the conduction of this transistor, and a signal that is generated after a certain period of time with the output of the transistor as input. An LED drive circuit comprising a delay circuit whose output is input to the R terminal of the D flip 70 tube.