Patent Application
20080129716
The present invention relates to liquid crystal display devices, and particularly to a liquid crystal display device having an analog-to-digital circuit.
A liquid crystal display (LCD) has the advantages of portability, low power consumption, and low radiation, and has been widely used in various portable information products such as notebooks, personal digital assistants (PDAs), video cameras, and the like. Furthermore, the LCD is considered by many to have the potential to completely replace CRT (cathode ray tube) monitors and televisions.
Referring to
Referring to
Referring to Table 1, this shows a corresponding relationship between the four-bit operating mode signals and the operating modes. The four-bit operating mode signals include a number of logic states, each of which contributes to determining an operating mode of the driving chip 110. The four-bit operating mode signals are defined by IM0, IM1, IM2 and IM3 respectively. For example, if the external circuit provides a four-bit operating mode signal such as “0100” to the interface circuit 130, the driving chip 110 works in a “16-bit interface and 80-system” operating mode. However, a four-bit operating mode signal “0110” or “**11” corresponds to an invalid setting. The symbol “*” can be a logic state “0” or “1”.
According to the above system, the LCD device 10 can work according to a number of different operating modes. Thus the LCD device 10 has good compatibility with a variety of external devices. However, the four-bit signal mode needs four conductive lines 171, 172, 173, 174 in the FPC 170. This makes an area of the FPC 170 rather large, and a layout of the FPC 170 relatively complex. Also, the complex layout is liable to induce crosstalk in the FPC 170.
In an alternative configuration, the LCD device 10 can have only one operating mode stored in the driving chip 110. In such case, most of the conductive lines 171, 172, 173, 174 in the FPC 170 can be omitted. However, this kind of alternative LCD device 10 has very limited compatibility with external devices.
What is needed, therefore, is a liquid crystal display device that can overcome the above-described deficiencies.
In one preferred embodiment, a liquid crystal display device includes a liquid crystal display panel, a flexible printed circuit and a driving chip. The flexible printed circuit includes a conductive line. The driving chip includes an interface circuit and an analog-to-digital circuit, the analog-to-digital circuit is configured for receiving an analog operating mode signal via the conductive line and transforming the analog operating mode signal to a digital operating mode signal, and providing the digital operating mode signal to the interface circuit. The digital operating mode signal determines an operating mode of the liquid crystal display device.
Other novel features and advantages of the present liquid crystal display device will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. In the drawings, all the views are schematic.
Reference will now be made to the drawing figures to describe various embodiments of the present invention in detail.
Referring to
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The reference voltage input terminal 262 receives a reference voltage from the reference voltage source 263. The reference voltage determines a converting range. The reference voltage is divided into a plurality of sub-range voltages, with each of the sub-range voltages having an amount of voltage width the same as an amount of voltage width of each of the other sub-range voltages. Every sub-range voltage corresponds to a four-bit operating mode signal. The analog signal input terminal 264 receives an analog signal, and then the analog-to-digital converter 261 outputs a corresponding four-bit digital signal.
The driving chip 210 includes a plurality of operating modes. Referring to Table 2, this shows relationships between the sub-range voltages, the four-bit digital signals, and the corresponding operating modes. The maximum valid reference voltage is 950 millivolts (mV), and a range of each sub-range voltage is 100 mV. The analog signal received by the analog-to-digital converter 261 is defined as “IM”, and the four-bit digital signals are defined as “IM0”, “IM1”, “IM2”, and “IM3” respectively. A four-bit operating mode signal “0110” or “**11” corresponds to an invalid setting. The symbol “*” can be a logic state “0” or “1”.
The operating mode of the interface circuit 230 is determined as follows. An external circuit (not shown) provides an analog signal to the analog-to-digital converter 261 via the conductive line 273 of the FPC 270. For example, the analog signal can be a voltage of 200 mV. The analog-to-digital converter 261 judges that 200 mV is between 150 mV and 250 mV according to Table 2. Thus, the analog-to-digital converter 261 transforms the analog signal to a four-bit digital signal “0100”. The four-bit digital signal “0100” is provided to the four operating mode signal terminals 231, 232, 233, 234 of the interface circuit 230 respectively. Then, the driving chip 210 works in a “16-bit interface, 80-system” operating mode.
Because the driving chip 210 includes the analog-to-digital circuit 260, the FPC 270 only needs one conductive line 273. Compared to a conventional FPC, a layout of the FPC 270 is simplified. In addition, the single conductive line 273 means that minimal (if any) crosstalk is induced in the FPC 270. Furthermore, an area of the FPC 270 can be reduced, so that a cost of the liquid crystal display 20 is correspondingly reduced.
It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set out in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 95144731 | Dec 2006 | TW | national |
