KR100373349B1 - Low power Source driver for LCD - Google Patents

Abstract

The present invention relates to a low power LCD source driving circuit capable of reducing power consumption by using a decoder and a multiplexer.

An LCD source driving circuit of the present invention includes a register for storing digital data of a predetermined bit applied from the outside; A buffer for inputting a plurality of output voltages provided from the resistor string; Decoding means for decoding data of a predetermined upper bit among digital data stored in the register; Switching means for selecting only a predetermined output voltage from among the plurality of output voltages from the buffer by the output decoding output signal of the decoding means; And a multiplexer for selecting only one output voltage among the predetermined output voltages provided from the switch means by the lower bit data among the digital data stored in the register and providing the output voltage to the liquid crystal panel.

Description

Low power source driver circuit {Low power Source driver for LCD}

The present invention relates to a liquid crystal display device, and more particularly, to an LCD source driver capable of reducing power consumption by using a multiplexer in which a decoder is mixed.

Among the LCD driving circuits, the LCD source driving circuit converts a digital input signal into an analog voltage and displays it on the LCD. In the LCD source driving circuit, the amplifier acts as a buffer to drive the voltage to the LCD at a given time.

1 is a block diagram of a conventional LCD source driving circuit. Referring to FIG. 1, a conventional LCD driving circuit may select one of a plurality of voltages of a resistor string 100 according to a register 101 for storing input digital data and digital data transmitted from the register 101. A multiplexer 102 for selection and a buffer 103 for providing a voltage selected by the multiplexer 102 to the LCD panel.

In the conventional LCD driving circuit as described above, when digital data is input from the outside, the input digital data is stored in the register 101, and the multiplexer 102 corresponds to one of a plurality of voltages of the resistor string 100. Is selected and provided to the buffer 103.

At this time, it takes time to reach the voltage of the resistor string 100 selected by the delay time composed of the resistor string 100 and the capacitor component of the LCD. In the related art, the multiplexer 102 and the LCD panel (not shown) are shown. The buffer 103 constituted by an amplifier is arranged in between, thereby reducing time.

However, since the buffers must be arranged for every output channel, there is a problem in that power consumption increases in proportion to the increase of the channel.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art as described above, and an object thereof is to provide an LCD source driving circuit which can reduce power consumption by using a multiplexer having decoder means.

1 is a configuration diagram of a conventional LCD source driving circuit,

2 is a configuration diagram of an LCD source driving circuit according to an embodiment of the present invention;

3 is a detailed configuration diagram of a multiplexer in the LCD source driving circuit of the present invention of FIG.

4 is an example of the multiplexer circuit of FIG. 3;

* Description of the symbols for the main parts of the drawings *

201: Register 203: Buffer

203: multiplexer with mixed decoder

200: resistance string 301: decoder

302: switch 303: multiplexer

The present invention for achieving the above object is a register for storing a predetermined bit of digital data applied from the outside; A buffer for inputting a plurality of output voltages provided from the resistor string; Decode the data of the upper bit of the digital data stored in the register to select only a predetermined output voltage of the plurality of output voltages from the buffer, and the corresponding output voltage of the predetermined output voltage by the data of the lower bit of the digital data stored in the register It is characterized by providing a source driving circuit of an LCD comprising a multiplexer having a decoder means for selecting only one output voltage to provide to the liquid crystal panel.

A multiplexer including the decoder means for decoding the higher bit data of the digital data stored in the register; Switching means for selecting only a predetermined output voltage from among the plurality of output voltages from the buffer by an output decoding signal of the decoder means; It consists of multiplexer means for selecting only one output voltage among the predetermined output voltages outputted through the switch by the data of the lower bit among the digital data stored in the register and providing it to the liquid crystal panel.

The decoder means comprises a 3 to 8 decoder for decoding the upper 3 bits of the digital data of the 6-bit digital data output from the register, the switch means is composed of 64 switches to be output from the 3 to 8 decoder Eight switches are simultaneously selected by the decoding output to provide eight output voltages of the 64 output voltages of the buffer to the multiplexer means. The multiplexer means selects one output voltage among the eight output voltages applied from the switch means by the lower three bits of digital data of the six bits of digital data output from the register, and provides it to the liquid crystal panel. to 1 consists of a multiplexer.

In addition, the present invention is a register for storing a predetermined bit of digital data applied from the outside; A buffer for inputting a plurality of output voltages provided from the resistor string; Decoding means for decoding data of a predetermined upper bit among digital data stored in the register; Switching means for selecting only a predetermined output voltage from among the plurality of output voltages from the buffer by the output decoding output signal of the decoding means; Provides a source driving circuit of an LCD comprising a multiplexer for selecting and providing only one output voltage of the predetermined output voltage provided from the switch means by the data of the lower bit among the digital data stored in the register. It is characterized by.

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the accompanying drawings in order to describe the present invention in more detail.

2 is a block diagram of an LCD source driving circuit according to an embodiment of the present invention.

2, an LCD source driving circuit according to an embodiment of the present invention includes a resistor string 200 for generating a reference voltage, a buffer 203 to which a reference voltage is applied from the resistor string 200; A multiplexer having a register 201 for storing digital data input from the outside and a decoder means for selecting and outputting one of the output voltages of the buffer 203 according to the output signal from the register 201 ( 202.

The operation of the LCD source driver driving circuit of the present invention having the configuration as described above is as follows.

First, the reference voltage generated by the resistor string 200 is provided to the buffer 203, and the buffer 203 provides the reference voltage applied from the resistor string 200 to the multiplexer 202 having decoder means. do.

The register 201 stores digital data applied from the outside, and the multiplexer 202 inputs digital data stored in the register 201 to output one of the output voltages provided from the buffer 203 to the digital data. Choose accordingly. Therefore, a reference voltage corresponding to digital data input from the outside is provided to the LCD panel (not shown) to drive the LCD panel.

In the LCD source driver of the present invention as described above, since the delay time is caused by the resistance component of the multiplexer 202 and the capacitor component of the LCD when the buffer 203 is operated, it is shown in FIG. 3 to reduce the resistance of the multiplexer. A multiplexer 203 having decoder means as described above is used.

Referring to FIG. 3, in the LCD source driver of the present invention, the multiplexer 202 having decoder means includes decoder means for inputting and decoding higher bit data of a predetermined bit of digital data output from the register 201 ( 301 and switch means 302 for selecting a corresponding voltage among the output voltages output from the buffer 203 according to the output signal of the decoder 310, and among the digital data output from the register 201. And multiplexer means 303 for inputting low-bit data of a predetermined bit and applying a corresponding one of the voltages output from the switch means 302 to the liquid crystal panel as a high-voltage reference voltage according to the low-bit data. .

4 shows an example of a multiplexer circuit having the decoder means of the present invention of FIG.

Referring to FIG. 4, the decoder means 301 is configured as a 3 to 8 decoder, and inputs the upper 3 bits of digital data A5, A4, and A3 of the 6 bits of digital data output from the register 201. 3 to 8 decoding is provided to the switch means 302.

The switch means 302 is composed of 64 switches, and among the 64-bit output signals provided from the buffer 203, only eight output signals are output by decoding output signals of the 3 to 8 decoders of the decoder means 301. It selects and delivers to the multiplexer means 303.

The multiplexer means 303 is composed of an 8 to 1 multiplexer, and inputs the lower 3 bits of digital data A2, A1, A0 of the 6-bit digital data output from the register 201 to the switch means 302. Eight output voltages from < RTI ID = 0.0 > 1) < / RTI > are selected according to the digital data A2, A1, A0, and provided to the liquid crystal panel as a reference voltage.

The operation of the multiplexer 202 having the decoder means of the present invention having the above configuration will be described below.

Of the 6 bits of data stored in the register 201 and supplied from the outside, three bits of data A5, A4 and A3 are applied to a 3 to 8 decoder which is a decoder means 301, and the 3 to 8 decoder is the upper 3 bits. Decode the digital data A5, A4 and A3 to generate eight decoded output signals.

Eight decoded output signals of the 3 to 8 decoder are provided to switch means 302 to simultaneously connect eight of the 64 switches. Accordingly, eight output voltages of the 64-bit output voltages output from the buffer 203 are selected and provided to the multiplexer means 303.

The multiplexer means 303 inputs three bits of low-order data A2, A1, A0 of the 6-bit digital data from the register 201, and among the eight buffer output voltages applied through the switch means 302. One is provided as an output channel. Accordingly, a predetermined voltage is applied to the liquid crystal panel to drive the liquid crystal panel.

In the LCD source driving circuit of the present invention as described above, for example, when applied to an LCD source driver having M bits of digital data and N channels, the current consumed by the amplifier constituting the buffer 203 is equal to M / N. Can be reduced.

According to the LCD driving circuit of the present invention as described above, it is possible to reduce the power consumption of the amplifier constituting the buffer by connecting a buffer consisting of an amplifier connected between the conventional multiplexer and the output channel between the resistor string and the multiplexer.

In addition, the LCD driving circuit of the present invention can reduce the delay time by reducing the resistance of the multiplexer by using a multiplexer having a decoder function instead of the multiplexer having only the conventional multiplexing function.

In addition, the above-mentioned effect becomes even greater when the LCD driving circuit of the present invention is applied to a 6-bit LCD source driving circuit used in a small game machine or a portable terminal.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims (12)

A register for storing digital data of a predetermined bit applied from the outside; A buffer for inputting a plurality of output voltages provided from the resistor string; Decode the data of the upper bit of the digital data stored in the register to select only a predetermined output voltage of the plurality of output voltages from the buffer, and the corresponding output voltage of the predetermined output voltage by the data of the lower bit of the digital data stored in the register A source driving circuit of an LCD comprising a multiplexer having decoder means for selecting only one output voltage to provide to a liquid crystal panel. 2. The multiplexer of claim 1 wherein said multiplexer comprising said decoder means Decoder means for decoding the higher bit data of the digital data stored in the register; Switching means for selecting only a predetermined output voltage from among the plurality of output voltages from the buffer by an output decoding signal of the decoder means; LCD source driving circuit comprising a multiplexer means for selecting only one output voltage among predetermined output voltages outputted through the switch based on the lower bit data among the digital data stored in the register and providing the same to the liquid crystal panel in. 3. The LCD source driving circuit according to claim 2, wherein said register stores 6 bits of digital data, and said buffer provides 64 output voltages. 4. The LCD source driving circuit as claimed in claim 3, wherein the buffer comprises an amplifier. 4. The LCD source driving circuit according to claim 3, wherein the decoder means comprises a 3 to 8 decoder for decoding the upper 3 bits of digital data of the 6 bits of digital data output from the register. The switch means according to claim 5, wherein the switch means comprises 64 switches, and eight switches are simultaneously selected by the decoding outputs output from the 3 to 8 decoders, thereby converting the eight output voltages from the 64 output voltages of the buffer. LCD source driving circuit, characterized in that provided by a multiplexer means. The liquid crystal display device according to claim 6, wherein the multiplexer means selects one output voltage among the eight output voltages applied from the switch means by lower 3 bits of digital data of 6 bits output from the register. An LCD source driving circuit comprising an 8 to 1 multiplexer for providing a panel. A register for storing digital data of a predetermined bit applied from the outside; A buffer for inputting a plurality of output voltages provided from the resistor string; Decoding means for decoding data of a predetermined upper bit among digital data stored in the register; Switching means for selecting only a predetermined output voltage from among the plurality of output voltages from the buffer by the output decoding output signal of the decoding means; A source driving circuit of an LCD comprising a multiplexer for selecting only one output voltage among the predetermined output voltages provided from the switch means by the lower bit data among the digital data stored in the register and providing the same to the liquid crystal panel. in. 9. The LCD source driving circuit according to claim 8, wherein said register stores 6 bits of digital data, and said buffer provides 64 output voltages. 10. The LCD source driving circuit according to claim 9, wherein the decoder means comprises a 3 to 8 decoder for decoding the upper 3 bits of digital data of the 6 bits of digital data output from the register. 11. The apparatus of claim 10, wherein the switch means comprises 64 switches, and eight switches are simultaneously selected by the decoding outputs output from the 3 to 8 decoders, thereby converting the eight output voltages from among the 64 output voltages of the buffer. LCD source driving circuit, characterized in that provided by a multiplexer means. 12. The liquid crystal display according to claim 11, wherein the multiplexer means selects one output voltage from among eight output voltages applied from the switch means by lower three bits of digital data of six bits of digital data output from the register. An LCD source driving circuit comprising an 8 to 1 multiplexer for providing a panel.