1. Field of the Invention
The present disclosure relates to a liquid crystal display (LCD) device and a driving method thereof, in which the size of a printed circuit board (PCB) with a driving circuit mounted thereon is reduced and the manufacturing cost is saved.
2. Discussion of the Related Art
LCD devices have numerous advantages, for example, advanced manufacturing technology, good drivability of a driving means, low power consumption, high-quality images, and a large screen. Therefore, LCD devices are popular. Also, LCD devices are being applied to various fields such as portable computers including notebook computers, office automation equipment, portable multimedia equipment, indoor/outdoor display devices, etc., and the application fields of LCD devices are continuously expanding.
LCD devices adjust the light transmittances of respective pixels according to an input video signal, thereby displaying an image.
FIG. 1 is a diagram illustrating a related art LCD device. FIG. 2 is a diagram illustrating a connection structure between a gamma block and data driver integrated circuit (IC) of the related art.
Referring to FIGS. 1 and 2, the related art LCD device includes a liquid crystal panel 10 that displays an image by using an input image signal, a backlight unit (not shown) that supplies light to the liquid crystal panel 10, and a driving circuit that drives the liquid crystal panel 10.
The liquid crystal panel 10 includes an upper substrate (color filter array substrate), a lower substrate (thin film transistor (TFT) array substrate), and a liquid crystal layer formed between the upper substrate and the lower substrate. The liquid crystal panel 10 includes a plurality of pixels that are arranged in a matrix type, and adjusts the transmittance of light irradiated from the backlight unit to display an image.
The driving circuit includes a gate driver (not shown), a data driver (not shown), a gamma voltage generator 40, a timing controller 50, and a power supply (not shown).
Here, a plurality of data driver ICs 20, the gamma voltage generator 40, and the timing controller 50 are mounted on a PCB 30.
The gate driver includes a plurality of gate driver ICs, and sequentially supplies a scan signal to a plurality of gate lines formed in the liquid crystal panel 10 to switch on the plurality of pixels.
The data driver includes the data driver ICs 20, and respectively supplies data voltages to a plurality of data lines formed in the liquid crystal panel 10.
Here, the data driver ICs 20 convert digital image data, supplied from the timing controller 50, into analog data voltages and supply the analog data voltages to the data lines, respectively.
The timing controller 50 aligns digital image data inputted from the outside and supplies the aligned data to the data driver ICs 20.
Moreover, the timing controller 50 generates a plurality of control signals for controlling the gate driver and the data driver, and supplies the control signals to the gate driver and the data driver, respectively.
As illustrated in FIG. 2, the gamma voltage generator 40 includes a plurality of gamma blocks 42, and respectively generates a plurality of gamma voltages to the data driver ICs 20.
A capacitor (not shown), which buffers a gamma voltage and outputs a certain voltage value, is disposed in an output terminal of each of the gamma blocks 42.
In FIG. 2, as an example, the gamma voltage generator 40 is illustrated as including ten gamma blocks 42. Each of the gamma blocks 42 includes two resistors that are connected serially between a driving voltage VDD terminal and a ground voltage GND terminal.
The gamma blocks 42 generate a first gamma voltage GMA1 to a tenth gamma voltage GMA10 (which have different values) by using two corresponding resistors that are connected serially between the driving voltage VDD terminal and the ground voltage GND terminal, respectively. Furthermore, the gamma blocks 42 supply the first gamma voltage GMA1 to the tenth gamma voltage GMA10 to the data driver ICs 20, respectively.
Here, the data driver ICs 20 convert the digital image data outputted from the timing controller 50 into the analog data voltages by using positive and negative gamma voltages GMA1 to GMA10 supplied from the gamma voltage generator 40.
A plurality of transmission lines 60 are formed on the PCB 30, and the gamma voltage generator 40 and the data driver ICs 20 are connected in parallel through the transmission lines 60. The gamma voltages GMA1 to GMA10 generated by the gamma voltage generator 40 are supplied to the data driver ICs 20 through the transmission lines 60.
In the related art LCD device having the above-described configuration, when the gamma voltage generator 40 is configured with ten gamma blocks 42, the plurality of transmission lines 60 are required to be formed on the PCB 30 for parallelly connecting the ten gamma blocks 42 and the data driver ICs 20.
Since the transmission lines 60 are formed on the PCB 30, the area of the PCB 30 increases. Due to this reason, much research is being recently conducted for reducing the area of the PCB 30 on which the driving circuit of the LCD device is mounted. However, since the transmission lines 60 are formed on the PCB 30, there is a limitation in decreasing the area of the PCB 30.
Moreover, a method of reducing the layer of a PCB is proposed for saving the manufacturing cost of LCD devices, but since the transmission lines 60 are formed on the PCB 30, there is a limitation in decreasing the layer of the PCB 30.
Moreover, twenty resistors R1 to R20 are required for generating the first gamma voltage GMA1 to the tenth gamma voltage GMA10 by using the ten gamma blocks 42, and ten capacitors are disposed in respective output terminals of the gamma blocks 42, causing the increase in the manufacturing cost of LCD devices.