CN213751896U - Backlight control circuit for pen-type LCD - Google Patents

Abstract

A backlight control circuit used for a pen-segment type LCD (liquid crystal display) comprises a display module driving chip, a gate circuit chip, a resistor and an NPN (negative-positive-negative) triode of the pen-segment type LCD, wherein the model of the display module driving chip is PCF 8576; the gate circuit chip, the resistor and the NPN triode are arranged on a circuit board of the pen-section type LCD; and are electrically connected. The utility model discloses display module driver chip based on LCD liquid crystal display, during the use, after a section formula LCD liquid crystal display starts, when display module driver chip got electric work, door circuit chip can get electric work, and then, the NPN triode switches on the power input end of exporting great electric current LED in a poor light, LED in a poor light gets electric work. This is novel need not external control port, in the application, under relevant circuit combined action, can realize LCD liquid crystal display's display module driver chip direct drive LED in a poor light, reaches compact structure from this, convenient to use's purpose. Based on the above, so this novel application prospect that has.

Description

Backlight control circuit for pen-type LCD

Technical Field

The utility model relates to a supporting technical field of a section formula LCD liquid crystal display, especially a backlight control circuit that a section formula LCD liquid crystal display used.

Background

The pen-segment LCD is generally used for displaying digital codes and fixed patterns, has the advantages of low cost and good display effect, and is widely applied. The pen-type LCD screen is not luminous enough, so that the digital code and fixed pattern displayed by the LCD screen can be watched by the outside by installing a backlight LED. At present, the drive of the display module driving chip and the backlight LED of the LCD liquid crystal display screen are separately controlled and used, that is to say, the display module driving chip can not drive the backlight LED, so that the existing pen-type LCD liquid crystal display screen adopts an independent port, and the LED is artificially controlled to be on or off, thereby bringing inconvenience to users, and increasing the backlight control alone, increasing the number of leads and leading to the equipment not to be compact.

In fact, the display module driving chip of the pen-segment type LCD liquid crystal display has a certain driving current, and if the driving chip is used for driving the backlight LED, the backlight LED works synchronously when the pen-segment type LCD liquid crystal display works, so that not only is the user not required to control the on and off of the backlight LED through the control port, but also the wiring points are reduced, and the device is more compact. However, due to the structural limitation of the display module driving chip of the existing pen-segment type LCD liquid crystal display, the driving display module is all voltage-driven, and the port current is very small, so that the high-current backlight LED cannot be directly driven. Taking the driving chip of PCF8576 display module as an example, the chip has I²The C bus interface has static drive and multi-line drive, and can be set by address bit, several same modules are connected on 2 communication lines, when it is worked, the signal output ends BP0 of PCF8576, Sn (Sn +1, etc.) can simultaneously output a series of waveform signals, these 2 signals are superimposed to produce display drive signal (for example, state1, state2 waveform) of LCD, in which the displayed point (state1) has rectangular wave signal, and the non-displayed point (state2) signal is 0, so that it can be known that the display module driving chip for driving LCD liquid crystal display screen is voltage-driven, its port current is very small, and can not directly drive large-current backlight LED.

SUMMERY OF THE UTILITY MODEL

In order to overcome the LED drive in a poor light of current stroke segmentation LCD liquid crystal display, because of the technological limit exists if the background the drawback, the utility model provides a based on LCD liquid crystal display's display module driver chip does not need external control port, uses, under relevant circuit combined action, can realize LCD liquid crystal display's display module driver chip direct drive LED in a poor light, reaches compact structure from this, convenient to use's a control circuit in a poor light that stroke segmentation LCD liquid crystal display used.

The utility model provides a technical scheme that its technical problem adopted is:

a backlight control circuit used for a pen-segment type LCD (liquid crystal display) comprises a display module driving chip, a gate circuit chip, a resistor and an NPN (negative-positive-negative) triode of the pen-segment type LCD, wherein the model of the display module driving chip is PCF 8576; the circuit is characterized in that the gate circuit chip, the resistor and the NPN triode are arranged on a circuit board of the pen-section type LCD; one input end of the gate circuit chip is electrically connected with two ends of a bus of the display module driving chip respectively, and two ends of a power supply input of the gate circuit chip are electrically connected with two ends of a power supply input of the pen-section type LCD respectively; the output end of the gate circuit chip is connected with one end of the first resistor, the other end of the first resistor is connected with one end of the second resistor and the base of the NPN triode, the collector of the NPN triode is connected with the negative electrode of the backlight LED of the pen-segment type LCD, the emitter of the NPN triode is connected with the other end of the second resistor, the third end is connected with the positive electrode of the backlight LED, and the other end of the third resistor, the other end of the second resistor, the emitter of the NPN triode and the two ends of the power input of the pen-segment type LCD are respectively and electrically connected.

Further, the gate chip model is 74HC 86.

The utility model has the advantages that: the utility model discloses display module driver chip based on LCD liquid crystal display, during the use, after a section formula LCD liquid crystal display starts, when display module driver chip got electric work, door circuit chip can get electric work, and then, the NPN triode switches on the power input end of exporting great electric current LED in a poor light, LED in a poor light gets electric work. This is novel need not external control port, in the application, under relevant circuit combined action, can realize LCD liquid crystal display's display module driver chip direct drive LED in a poor light, reaches compact structure from this, convenient to use's purpose. Based on the above, so this novel application prospect that has.

Drawings

The present invention will be further explained with reference to the drawings and examples.

Fig. 1 is a circuit diagram of the present invention.

Detailed Description

As shown in fig. 1, a backlight control circuit for a pen-segment LCD liquid crystal display includes a display module driving chip a1, a gate chip a2, resistors R1, R2, R3, and an NPN transistor Q1 of the pen-segment LCD, where the display module driving chip a1 is PCF 8576; the gate circuit chip A2, the resistors R1, R2 and R3 and the NPN triode Q1 are arranged on a circuit board of the pen-section type LCD liquid crystal display screen; two input ends 1 and 2 of one path of the gate circuit chip A2 are respectively connected with two ends of a bus of a display module driving chip A1 through leads, and two ends 14 and 7 of a power input of the gate circuit chip A2 are respectively connected with two ends G of a power input of a pen-section type LCD A3 through leads; the output end 3 pin (other pins are suspended) of the gate circuit chip A2 is connected with one end of a first resistor R1, the other end of the first resistor R1 is connected with one end of a second resistor R2 and the base of an NPN triode Q1, the collector of the NPN triode Q1 is connected with the negative electrode of a backlight LED of the pen-segment type LCD, the emitter of the NPN triode Q1 is connected with the other end of the second resistor R2, one end of a third resistor R3 is connected with the positive electrode of the backlight LED, and the other end of the third resistor R3, the other end of the second resistor R2, the emitter of the NPN triode Q1 and two ends G of the power input of the pen-segment type LCD are respectively connected through wires. Gate chip A2 model 74HC 86.

FIG. 1 shows, the utility model discloses display module driver chip A1 based on LCD liquid crystal display, during the use, after a section formula LCD liquid crystal display A3 starts, when display module driver chip A1 gets electric work, the power gets into 14 feet and 7 feet of door circuit chip A2, and door circuit chip A2 can get electric work, shows that gate circuit chip A2 can get electric workModule driving chip A1 working I²When the voltage signal output by the C bus interface is transmitted to the static driving and multi-row driving chips of the pen-segment LCD, the voltage signal enters one of the signal input terminals 1 and 2 of the gate chip a2, the voltage signal is amplified and output by 3 pins, and then the voltage signal is reduced and limited by the resistor R1 and enters the base (higher than 0.7V) of the NPN triode Q1, so that the NPN triode Q1 is turned on (the resistor R2 is a peripheral element of the NPN triode Q1 as a voltage divider), and the collector outputs a low level to enter the negative power input terminal of the backlight LED. This novel LED in a poor light does not need external control port, in the application, under relevant circuit combined action, can realize LCD liquid crystal display's display module driver chip direct drive LED in a poor light, reaches compact structure from this, convenient to use's purpose. The resistors R1, R2 and R3 are respectively 10K, 4.7K and 1.8K, and the model of the NPN triode Q1 is 9013.

Having shown and described the fundamental principles and essential features of the invention and its advantages, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, but is capable of other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Furthermore, it should be understood that although the present description refers to embodiments, the embodiments do not include only one independent technical solution, and such description is only for clarity, and those skilled in the art should take the description as a whole, and the technical solutions in the embodiments may be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims (2)

1. A backlight control circuit used for a pen-segment type LCD (liquid crystal display) comprises a display module driving chip, a gate circuit chip, a resistor and an NPN (negative-positive-negative) triode of the pen-segment type LCD, wherein the model of the display module driving chip is PCF 8576; the circuit is characterized in that the gate circuit chip, the resistor and the NPN triode are arranged on a circuit board of the pen-section type LCD; one input end of the gate circuit chip is electrically connected with two ends of a bus of the display module driving chip respectively, and two ends of a power supply input of the gate circuit chip are electrically connected with two ends of a power supply input of the pen-section type LCD respectively; the output end of the gate circuit chip is connected with one end of the first resistor, the other end of the first resistor is connected with one end of the second resistor and the base of the NPN triode, the collector of the NPN triode is connected with the negative electrode of the backlight LED of the pen-segment type LCD, the emitter of the NPN triode is connected with the other end of the second resistor, the third end is connected with the positive electrode of the backlight LED, and the other end of the third resistor, the other end of the second resistor, the emitter of the NPN triode and the two ends of the power input of the pen-segment type LCD are respectively and electrically connected.

2. The backlight control circuit for a pen-type LCD liquid crystal display as claimed in claim 1, wherein the gate chip type is 74HC 86.

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