TWI385617B - Multifunctional backlight module circuit - Google Patents

Description

Multi-function backlight module circuit

The invention relates to a backlight module circuit, in particular to a multifunctional backlight module circuit, which can be used for driving a backlight panel, and can also be used for driving a peripheral function module.

In recent years, the technology of liquid crystal display modules has been quite mature, and due to its light and thin features, it is widely used in portable electronic devices such as a personal digital assistant (PDA) or a mobile phone (Mobile Phone). The backlight module in the liquid crystal display module is an indispensable component, and the backlight panel of the backlight module mainly has two types of a cold cathode tube and a light emitting diode. Nowadays, the backlight module technology of the light-emitting diode has gradually matured, so that the luminous efficiency can be kept in parallel with the cold cathode tube, and the light-emitting diode has many advantages such as small volume, fast reaction speed and good color rendering.

In portable devices, the voltage of the battery is usually insufficient to drive the light-emitting diodes to emit the required brightness. Therefore, a dedicated backlight module circuit is required to operate. Please refer to FIG. 1 , which shows a conventional backlight module circuit 10 . The conventional backlight module circuit 10 mainly includes a boost DC-DC converter 12 and a backlight panel 14. The battery is supplied with an input voltage Vin, and after being boosted, an output voltage Vout is output to drive the backlight panel 14 to emit light. The backlight panel 14 is directly controlled by a power control signal Power_Control.

Usually in a portable device, in addition to the backlight panel 14, there are many weeks. The edge function module requires power supply. Such peripheral function modules can be sound modules such as buzzer circuits, indicator number modules such as high-intensity indicating light-emitting diodes, and other functional modules such as Laser Poinfer. Taking the buzzer circuit as an example, the power supply of the general buzzer circuit is simply using the battery voltage directly. However, when the portable device adopts a low battery voltage design scheme, such as a single aluminum battery, the buzzer circuit may be insufficient in voltage, resulting in a loud sound of the portable device. At this point, another power converter needs to be added to raise the battery voltage to the voltage required by the buzzer circuit, enough to drive the buzzer circuit normally. However, the addition of a power converter will result in an additional cost increase.

Therefore, it is necessary to develop a multi-function backlight module circuit, which can be used to drive the backlight panel, and can also be used to drive peripheral function modules.

One object of the present invention is to provide a multi-function backlight module circuit for driving a backlight panel and a peripheral function module. The multi-function backlight module circuit comprises: a power converter that receives an input power and outputs an output power; a first feedback circuit has a switching component, and the first feedback circuit generates a first feedback And returning to the power converter, so that the output power source can drive the backlight panel, wherein the switching component controls the backlight panel according to a backlight control signal; and a second feedback circuit generates a second feedback signal and returns The power converter is granted to enable the output power to drive the peripheral function module. The first feedback circuit also includes a backlight panel and a first resistor, so that a current flowing through the backlight panel generates a first feedback signal on the first resistor. The second feedback circuit is formed by connecting a second resistor and a third resistor in series, so that the current flowing through the third resistor is A second feedback signal is generated on the two resistors. When the switching element is not turned on, the first feedback signal does not maintain the output power because no current flows through the first resistor. At this time, the second feedback signal continuously controls the power converter to maintain the output power for the peripheral function module. Needed.

In order to enable the reviewing committee to further understand the technical features and contents of the present invention, the following description will be made in conjunction with the drawings and preferred embodiments.

Please refer to FIG. 2, which illustrates a preferred embodiment of a multi-function backlight module circuit of the present invention. The multi-function backlight module circuit 20 of the preferred embodiment is used to drive a backlight panel 24 and a peripheral function module (not shown). The multi-function backlight module circuit 20 includes a power converter 22 that receives an input power source Vin and outputs an output power source Vout. A first feedback circuit 26 generates a first feedback signal and sends it back to The power converter 22 is configured to enable the output power source Vout to drive the backlight panel 24; and a second feedback circuit 28 to generate a second feedback signal and feedback to the power converter 22 to make the output power source Vout The power module V_Power of the function module is used to drive the peripheral function module.

In the preferred embodiment, the first feedback circuit 26 includes a backlight panel 24 and a first resistor R1, such that the voltage generated by the current flowing through the backlight panel 24 on the first resistor R1 is a first feedback signal. Since the backlight panel 24 and the first resistor R1 are connected in series, the current flowing through the backlight panel 24 and the first resistor R1 is the same, so that the voltage generated on the first resistor R1 is the first feedback signal, which can represent the backlight panel 24 The power consumed can also reflect the brightness of the backlight panel 24. Thereby, the first feedback signal is fed back to the power converter 22, so that the backlight panel 24 can maintain a stable and uniform brightness. Among them, the first The resistor R1 is a current limiting resistor of one ohm (Ohm) level.

In the preferred embodiment, the first feedback circuit 26 includes a switching element Q1 for controlling the backlight of the backlight panel 24 according to a backlight control signal Backlight_Control. The switching element Q1 is a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET). When the switching element Q1 is not turned on, no current flows through the backlight panel 24, and the backlight panel 24 does not emit light; and when the switching element Q1 is turned on, current flows through the backlight panel 24, and the backlight panel 24 emits light. Moreover, when the switching element Q1 is not turned on, the first feedback signal does not maintain the output power supply Vout, and at this time, the second feedback circuit 28 functions to continuously control the power converter to maintain the output power Vout by the second feedback signal. To provide the power supply V_Power required for the peripheral function module. Compared with the conventional backlight module circuit 10, the backlight panel 14 is directly controlled by a power control signal Power_Control, and the backlight panel 24 of the embodiment is controlled by a backlight control signal Backlight_Control, which can make the backlight module The backlight panel 24 of the group is normally turned off and enters the power saving mode. At this time, the second feedback signal continuously controls the power converter to maintain the output power Vout without affecting the power required by other peripheral function modules.

In the preferred embodiment, the second feedback circuit 28 can be a voltage dividing circuit, which is formed by a second resistor R2 and a third resistor R3 connected in series, so that the current flowing through the third resistor R3 is in the second A second feedback signal is generated on resistor R2. The resistance ratio of the second resistor R2 and the third resistor R3 can be adjusted according to the actual needs of the peripheral function module to generate a suitable second feedback signal to control the output power supply Vout of the power converter 22 to conform to the peripheral function module. Demand. In the actual design, the second resistor can be matched with the first resistor R1 of the ohmic level. The resistance R2 is set to the resistance of the kilohm (KOhm) level, so that the first resistor R1 does not affect the normal operation of the first feedback signal due to the parallel connection.

In the preferred embodiment, the power converter 22 can further include an output voltage protection (OVP) circuit to prevent the second feedback signal from being generated by the power converter 22 beyond the peripheral function module. Output power supply Vout. This is particularly suitable when the resistance of the third resistor R3 is greater than the resistance of the first resistor R1. The backlight panel 24 is open due to a defect, and the switching element Q1 is in an on state, so that the third resistor R3 and the third resistor can be avoided. The feedback generated by a resistor R1 causes the power converter 22 to output a power source that exceeds the range that the peripheral function module can withstand.

In the preferred embodiment, the power converter is a boost DC-DC converter. The backlight panel 24 is formed by connecting a plurality of light-emitting diodes D1 to Dn in series, and the plurality of light-emitting diodes D1 to Dn can be white light. The peripheral function module can be a sound module such as a buzzer circuit, a light indicator module such as a high brightness indicating light emitting diode, or other functional modules such as a Laser Pointer.

The above is only one preferred embodiment of the present invention, but the scope of the present invention is not limited to the embodiment, but should be based on the scope of the patent application. Any changes and modifications made by those skilled in the art in the spirit of the present invention are not departing from the scope of the invention.

10‧‧‧Learning backlight module circuit

12‧‧‧Power Converter

14‧‧‧ Backlit panel

20‧‧‧Multifunctional backlight module circuit

22‧‧‧Power Converter

24‧‧‧Backlit panel

26‧‧‧First feedback circuit

28‧‧‧Second feedback circuit

1 is a schematic diagram of a conventional backlight module circuit; and FIG. 2 is a diagram showing a preferred embodiment of a multi-function backlight module circuit of the present invention.

20‧‧‧Multifunctional backlight module circuit

22‧‧‧Power Converter

24‧‧‧Backlit panel

26‧‧‧First feedback circuit

28‧‧‧Second feedback circuit

Claims (9)

A multi-function backlight module circuit for driving a backlight panel and a peripheral function module, the multi-function backlight module circuit comprising: a power converter, receiving an input power, and outputting an output power; The feedback circuit has a switching element and a first resistance of one ohm level, and a current flowing through the backlight panel generates a first feedback signal to the first resistor and is fed back to the power converter to make the output The power source is configured to drive the backlight panel, wherein the switching component controls the backlight panel according to a backlight control signal; and a second feedback circuit includes a second resistor of a kiloohm level and a third resistor, the second The resistor is connected in series with the third resistor, and the second resistor and the third resistor are electrically connected between the backlight panel and the first resistor, and the first feedback signal is passed through the second resistor and the third resistor Returning to the power converter, and a current flowing through the third resistor generates a second feedback signal on the second resistor and is fed back to the power converter to enable the output power to drive the periphery Energy modules. The multi-function backlight module circuit of claim 1, wherein the backlight panel and the first resistor are connected in series, and the first resistor is a current limiting resistor. The multi-function backlight module circuit of claim 1, wherein the switching element is a metal oxide half field effect transistor. The multi-function backlight module circuit of claim 1, wherein the second feedback signal controls the power converter to maintain the output power for the peripheral function module when the switching element is non-conducting Required. The multi-function backlight module circuit as claimed in claim 1, wherein The power converter further includes an output voltage protection circuit to prevent the second feedback signal from causing the power converter to generate more than the output power that the peripheral function module can withstand. The multi-function backlight module circuit of claim 1, wherein the power converter is a boost DC-DC power converter. The multi-function backlight module circuit of claim 1, wherein the backlight panel is composed of at least one light-emitting diode. The multi-function backlight module circuit of claim 7, wherein the light-emitting diode system is white light. The multi-function backlight module circuit of claim 1, wherein the peripheral function module comprises a buzzer, a high-intensity indicating light-emitting diode or a light pen.