JP2001092425A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a situation, in which a user thinks of a malfunction of a liquid crystal display device having a digital transmission standard or a personal computer when the device displays noting on a liquid crystal panel if signals out of a display range are inputted, by displaying a picture on the screen. SOLUTION: A detecting section 3 detects inputted synchronizing signals. When it is discriminated that there exists no signal or it is out of a frequency range, a switching is made to switch to a clock and synchronizing signals which are not synchronized to the input signals and the picture is displayed on the panel so that the user recognizes an abnormal condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a TMDS (Transition Minimized Differential Sig).
naling) transmission and LVDS (Low Voltage Differential Signali)
ng) It is also about technology that is effective for digital interface between personal computer and monitor such as transmission.

[0002]

2. Description of the Related Art In recent years, information processing has progressed and word processors and personal computers have penetrated offices and homes. However, miniaturization has progressed along with high performance and high functionality. Lightweight ones are desired. Liquid crystal display devices are widely used as display devices for portable movies, notebook computers, and the like because they are thinner, lighter, and consume less power than conventional CRT display devices. Conventionally, analog signals have been used for connecting these video devices. CR for liquid crystal display devices
Analog signal transmission has been performed due to the compatibility of T display devices.

However, since the liquid crystal panel itself is a digital signal display element and a video signal output section itself called a graphic controller of a personal computer or the like is digitally output, the digital signal is once converted to a digital signal. The analog signal was converted by the converter, and the digital signal was converted by the A / D converter when the signal was input to the liquid crystal panel again. Image degradation occurs due to repetition of conversion, noise contamination in the transmission path, and the like. Further, the frequency characteristics of the video signal are increased due to the large screen and high definition, and the amount of information is increased. Further, there is an increase in cost due to the conversion. For these reasons, the advantage of analog transmission in liquid crystal display devices has been increasingly lost.

[0004] Therefore, VESA (Video Electron
ics Standards Association) has established a digital transmission standard for liquid crystal display devices, and JEIDA (Japan El
ectronic Industry Development Association) is promoting the standardization of standards. Figure 3 shows the JEIDA-59-1999 JEIDA standard “Digital Monitor Interface Standard Version 1.
FIG. 1 shows a configuration diagram of a liquid crystal display device in TMDS transmission of a digital interface described as “0”.

In FIG. 3, a graphic controller 3 for digitally outputting an image of a personal computer or the like is provided.
1 and a transmitter 3 for converting a parallel signal and a serial signal output from the graphic controller 31
2, a receiver 33 that converts a serial signal converted into a serial signal and transmitted through a transmission path into a parallel signal, and a liquid crystal panel 34 that displays a video signal. In the graphic controller 31, RGB image data 24 bits (8 bits ×
3) and a horizontal / vertical synchronization signal or a composite synchronization signal and clock. These signals are input to the transmitter 32, serially converted, and output to the outside.
The signal connected to the liquid crystal display device via the cable is input to the receiver 33. The input serial signal is converted to the original parallel signal after the parallel conversion, and is displayed on the liquid crystal panel 34 as it is.

[0006]

In the liquid crystal display device of the digital transmission standard, when the video signal from the graphic controller 31 is a signal other than the specifications that can be displayed on the liquid crystal panel 34, or when the video signal enters the power saving mode. It is conceivable that a video signal is not output from the graphic controller 31 and no signal is input to the liquid crystal panel 34.

In such a case, the transmitter 32 and the receiver 33 do not output any or all of the synchronization signal, clock, and video signal. At this time, the liquid crystal panel 34
Does not display anything at all, and there is a problem that a user using this liquid crystal display device thinks that the liquid crystal display device or personal computer has failed, but has no means for determining this.

SUMMARY OF THE INVENTION It is an object of the present invention to improve a user interface so that a user can recognize when a no signal or a video signal outside a display range is input to a liquid crystal display device in a digital interface.

[0009]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides a method for determining whether a video signal input by TMDS transmission or LVDS transmission of a digital interface has no input or a horizontal frequency or a vertical frequency is within a display range. Is determined and the synchronization from the pulse generation unit is given to the liquid crystal panel even when the liquid crystal panel is out of the display range, so that an image can be displayed on the liquid crystal screen.

Thus, when the input signal is out of the display range, it is possible to recognize that the frequency is out of the frequency range by displaying the synchronized image on the liquid crystal screen. In addition, TMDS transmission of digital interface or LVDS
Determines whether the video signal input during transmission is non-input or the horizontal frequency or vertical frequency is within the display range. Even if the video signal is outside the display range, the synchronization from the pulse generator is given to the liquid crystal panel and further on-screen display Is possible.

With this arrangement, when the input signal is out of the display range, the liquid crystal screen recognizes that the frequency is out of the frequency range by displaying the synchronized video, and furthermore, on-screen displays the determination result of the input video signal. By displaying, it is possible to recognize which part of the input signal is out of the range.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention uses TMDS transmission or LV of a digital interface.
In a liquid crystal display device to which a video signal is input by DS transmission,
A liquid crystal display device characterized by being able to display an image on a liquid crystal screen when an input video signal is not input or when the horizontal frequency or the vertical frequency is out of the display range. Has the effect of generating a free-running pulse and applying it to a liquid crystal panel to display an image on a liquid crystal screen.

According to a second aspect of the present invention, in a liquid crystal display device to which a video signal is inputted by TMDS transmission or LVDS transmission of a digital interface, a receiver for converting a serially transmitted video signal, a synchronization signal, and a clock into parallel signals is provided. A determination unit that determines whether a video signal that can be displayed on a liquid crystal panel is input from a parallel-converted synchronization signal, and a clock that is asynchronous with an input clock or an input video signal generated inside the liquid crystal display device. A pulse generator that generates a synchronization signal that can be displayed on a liquid crystal panel, a selector that switches between a synchronization signal input based on a result determined by the determination unit and a synchronization signal generated by the pulse generator, The clock input based on the determination result from the determination unit and the input video signal generated inside the liquid crystal display device are not A liquid crystal display device comprising a selector for switching between clocks of the same period and a liquid crystal panel. If the input signal is determined and is determined to be out of the range, a free-run pulse is generated and applied to the liquid crystal panel to provide the liquid crystal panel with a signal. It has the effect of displaying an image.

According to a third aspect of the present invention, in a liquid crystal display device to which a video signal is input by TMDS transmission or LVDS transmission of a digital interface, the input video signal is non-input or a horizontal frequency or a vertical frequency is displayed. This is a liquid crystal display device that can display an abnormal condition on the liquid crystal screen by displaying an on-screen signal when it is out of the range.If the input signal is judged and it is judged that it is out of the range, a free-run pulse is generated and the liquid crystal is displayed. It has the effect of giving an image to a panel, displaying an image on a liquid crystal screen, and displaying a determination result in an on-screen signal.

According to a fourth aspect of the present invention, in a liquid crystal display device to which a video signal is inputted by TMDS transmission or LVDS transmission of a digital interface, a receiver for parallel-converting a serially transmitted video signal, a synchronization signal, and a clock is provided. And a determination unit for determining whether a video signal that can be displayed on a liquid crystal panel is input from a parallel-converted synchronization signal, and a clock that is asynchronous with the input clock or an input video signal generated inside the liquid crystal display device. A pulse generator that generates a synchronization signal that can be displayed on the liquid crystal panel, an OSD generator that generates an on-screen signal, and a synchronization signal and a pulse generator that are input based on the result determined by the determination unit. A selector for switching the synchronization signal generated in the step (a), and a clock and a liquid input based on a result determined by the determination unit. A selector for switching between asynchronous clock from the input video signal generated inside the display device,
A selector for switching between an input video signal and an on-screen signal based on the result of the determination by the determination unit, and a liquid crystal display device including a liquid crystal panel. Has a function of generating a free-run pulse and giving the pulse to a liquid crystal panel, displaying an image on a liquid crystal screen, and displaying a determination result in an on-screen signal. Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

(Embodiment 1) FIG. 1 is a block diagram of a liquid crystal display device according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 1 denotes a receiver unit that converts a serially transmitted video signal, synchronization signal, and clock into parallel signals.
Reference numeral 2 denotes a selector, reference numeral 5 denotes a liquid crystal panel, and reference numeral 3 denotes a determination whether the synchronization signal parallel-converted by the receiver unit 1 is within the display range of the liquid crystal panel 5 and controls the selector 2 when the synchronization signal is out of the frequency range. Numeral 4 designates a pulse generator for generating the optimum synchronization for the liquid crystal panel 5.

The video signal, the synchronizing signal, and the clock serially converted by the receiver unit 1 can be directly connected to the liquid crystal panel 5. Here, when a synchronization signal is not input in the power save mode or the like, the synchronization signal is not input to the liquid crystal panel 5, and no image is displayed. Furthermore, an irregular signal may be input depending on the liquid crystal panel. Therefore, the determination unit 3 determines whether the input synchronization signal is a frequency that can be displayed on the liquid crystal panel or whether there is no input. If the input synchronization signal is within the range, the input synchronization signal and the clock are selected by the selector 2 and the liquid crystal is selected. Panel 5
Give to. If it is out of the range, the clock is switched to a free-running clock irrelevant to the input signal by the selector 2, the pulse generator 4 generates an optimum synchronizing signal for the liquid crystal panel 5, Give 5

With the above configuration, when the input signal is out of the frequency range or when there is no input, the video signal can flow and be displayed.

(Embodiment 2) FIG. 2 is a block diagram of a liquid crystal display device according to Embodiment 2 of the present invention. In FIG. 2, reference numeral 1 denotes a receiver unit that converts a serially transmitted video signal, a synchronization signal, and a clock into parallel signals.
Reference numeral 2 denotes a selector, reference numeral 5 denotes a liquid crystal panel, and reference numeral 3 denotes a determination that the synchronization signal parallel-converted by the seabar unit 1 is present within a display range of the liquid crystal panel 5. Reference numeral 4 denotes a pulse generator for performing optimal synchronization generation on the liquid crystal panel 5, and 6 comprises an OSD generator for causing the liquid crystal panel 5 to display an on-screen signal.

The video signal, the synchronizing signal, and the clock serially converted by the receiver unit 1 can be directly connected to the liquid crystal panel 5. Here, when the synchronization signal is not input in the power save mode or the like, no image is displayed on the liquid crystal panel 5 because the synchronization signal is not input. Further, an abnormal screen may be displayed. Therefore, the determination unit 3 determines whether the input synchronization signal is a frequency that can be displayed on the liquid crystal panel or whether there is no input. If the input synchronization signal is within the range, the input synchronization signal and the clock are selected by the selector 2 and the liquid crystal is selected. Give to panel 5. If the clock is out of the range, the clock is switched by the selector 2 to a free-running clock irrelevant to the input signal, and the pulse generator 4 generates an optimum synchronizing signal to the liquid crystal panel 5 so that the selector 2
To the liquid crystal panel 5. Further, the pulse generator 4 supplies a synchronization signal to the OSD generator 6 for generating an on-screen signal.

With this arrangement, when the input signal is out of the frequency range or when there is no input, the video signal can flow and be displayed, and the on-screen signal can be displayed. The result determined in 3 can be displayed.

[0022]

As described above, according to the present invention, in a liquid crystal display device to which a video signal is input by TMDS transmission or LVDS transmission of a digital interface, the input video signal has no input or the horizontal frequency or the vertical frequency is low. Even when the receiver does not output a synchronization signal or a clock outside the display range, it is possible to display an image flowing on the liquid crystal screen, which has an effect of allowing a user to recognize an abnormal state. In addition, TMDS transmission of digital interface or LVDS
In a liquid crystal display device to which video signals are input during transmission, even if the input video signal is not input or the horizontal or vertical frequency is out of the display range and the receiver does not output the synchronization signal, clock or video signal, on-screen display By displaying the determination result in the above, there is an effect that the user can recognize the abnormal state and its cause.

[Brief description of the drawings]

FIG. 1 is a block diagram of a liquid crystal display device according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram of a liquid crystal display device according to Embodiment 2 of the present invention.

FIG. 3 is a block diagram of a conventional liquid crystal display device.

[Explanation of symbols]

 1 Receiver 2 Selector 3 Judgment unit 4 Pulse generation 5 Liquid crystal panel 6 OSD generation unit

Claims (4)

[Claims] In a liquid crystal display device to which a video signal is input by TMDS transmission or LVDS transmission of a digital interface, when an input video signal is non-input and the horizontal frequency or the vertical frequency is any one out of a display range. A liquid crystal display device capable of displaying images on a liquid crystal screen. 2. A liquid crystal display device to which a video signal is input by TMDS transmission or LVDS transmission of a digital interface, a receiver section for converting a serially transmitted video signal, a synchronization signal, and a clock into a parallel signal, and a parallel-converted synchronization signal. A determination unit that determines whether a video signal that can be displayed on the liquid crystal panel is input from the LCD, and a synchronous that can be displayed on the liquid crystal panel with an input clock or a clock that is asynchronous with the input video signal generated inside the liquid crystal display device A pulse generation unit that generates a signal, a selector that switches between a synchronization signal input based on the result determined from the determination unit and a synchronization signal generated by the pulse generation unit, and a selector that determines the result from the determination unit. A selector for switching between a clock input to the LCD and an asynchronous clock for an input video signal generated inside the liquid crystal display device. Liquid crystal display device comprising a liquid crystal panel. 3. A liquid crystal display device to which a video signal is inputted by TMDS transmission or LVDS transmission of a digital interface, in a case where the inputted video signal is no input, and the horizontal frequency or the vertical frequency is out of the display range. A liquid crystal display device capable of displaying an abnormal state on a liquid crystal screen by displaying an on-screen signal. 4. A liquid crystal display device to which a video signal is inputted by TMDS transmission or LVDS transmission of a digital interface, a receiver section which converts a serially transmitted video signal, a synchronization signal, and a clock into parallel, and a parallel-converted synchronization signal. A determination unit that determines whether a video signal that can be displayed on the liquid crystal panel is input from the LCD, and a synchronous that can be displayed on the liquid crystal panel with an input clock or a clock that is asynchronous with the input video signal generated inside the liquid crystal display device A pulse generator that generates a signal, an OSD generator that generates an on-screen signal, and a selector that switches between a synchronization signal input based on a result determined by the determination unit and a synchronization signal generated by the pulse generator. And a clock input based on the result determined by the determination unit and an input video signal generated inside the liquid crystal display device. The liquid crystal display device including a selector for switching between asynchronous clock, the selector for switching the video signal and on-screen signal inputted on the basis of the judgment result of the judging section, the liquid crystal panel.