JPH03284072A - Planer type display device - Google Patents

Abstract

PURPOSE:To obtain an easy to see picture without missing for the display of an on-screen signal by shifting a pulse eliminating timing of a pulse signal to an on-screen circuit and a vertical driver circuit by a delay time attended with sample-and-hold processing of a video signal. CONSTITUTION:Horizontal display position information is inputted to a liquid crystal display panel 1 from a horizontal driver circuit 2, vertical display position information is inputted from a vertical driver circuit 3, the panel 1 holds a video signal from a signal synthesizer 4 and writes it into a cell of display position information commanded. The circuit 2 forms display position information in the horizontal direction synchronously with an incoming 1st pulse signal INHH and outputs the information to the panel 1. The circuit 3 forms vertical display information synchronously with a 2nd pulse signal INHV1 inputted from an interleave circuit 10 to output it to the panel 1. The signal INHH and a system command signal P/N are inputted to the interleave circuit 10, the pulse signals are outputted as they are in the case of the NTSC system and the pulse signal is interleaved in the case of the PAL system and outputted to the circuits 3, 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flat display device capable of displaying at least two types of video signals having different numbers of horizontal scanning lines.

[Prior Art] For example, some portable flat panel television receivers include
Some devices are capable of displaying video signals according to multiple television standards, taking into account that they can be carried in areas that follow different television standards. For example, there are devices that can display video signals of the so-called NTSC system and PAL system.

Here, the number of horizontal scanning lines in the PAL system is 625,
The number of horizontal scanning lines in the NTSC system is 525, which is approximately 6.
; 5, the conventional device performs normal display operations for NTSC video signals, and displays every 6th horizontal scanning line for PAL video signals by 5. These two systems are supported by converting the image into horizontal scanning lines and displaying it. FIG. 4 shows the configuration around the display device of such a two-system compatible liquid crystal television receiver.

In FIG. 4, the liquid crystal display panel 1 is given horizontal display position information from the horizontal driver circuit 2.
Further, display position information in the vertical direction is given from the vertical driver circuit 3, and the liquid crystal display panel 1 writes a video signal from a signal synthesizer 4, which will be described later, into a cell of the designated display position information and displays it. Here, the liquid crystal display panel 1 performs a writing operation after sampling and holding a video signal, and through this operation, the LH (horizontal scanning period)
There is a delay for a period of

The horizontal driver circuit 2 forms horizontal display position information and outputs it to the liquid crystal display panel 1 in synchronization with a first pulse signal INHH in which a spike-like pulse occurs every IH. The vertical driver circuit 3 forms vertical display position information in synchronization with the second pulse signal INHV given from the thinning circuit 5 and outputs it to the liquid crystal display panel 1.

The thinning circuit 5 is supplied with a first pulse signal I NHH and a method command signal P/N. The thinning circuit 5 is
When the system command signal P/N indicates the NTSC system, the incoming first pulse signal INHH is sent directly to the second pulse signal.
When the pulse signal I NHV is output and the system command signal P/N indicates the PAL system, one pulse is thinned out for every 6 pulses of the first pulse signal that arrives. The signal is converted into the second pulse signal INH■
Output as .

Accordingly, in the case of the PAL system, the vertical driver circuit 3 outputs the same vertical display position information for two consecutive horizontal scanning lines every six horizontal scanning lines, and outputs the same vertical display position information for two consecutive horizontal scanning lines every six horizontal scanning lines. The video signals of the scanning lines are displayed on the same line of the liquid crystal display panel 1, and a 5/6 conversion display is realized.

By the way, when switching channels, changing the volume, etc., channel designating numbers and the like are superimposed and displayed on the video signal. Therefore, the on-screen circuit 1i86 and the signal synthesizer 4 described above are provided. The on-screen circuit 6 has an on-screen command ON and a vertical synchronization signal V.
D and a second pulse signal INHV are provided. After receiving the vertical synchronization signal VD, the on-screen circuit 6 counts the second pulse signal INHV and outputs an on-screen signal at a timing based on this count value. That is, the on-screen signal itself is not thinned out, and the on-screen circuit code is output according to the number of arriving pulses. As a result, in both the NTSC system and the PAL system, on-screen characters are displayed in the same position and in the same size. , [Problems to be Solved by the Invention] FIG. 5 shows a timing chart of each part when the PAL system is instructed.

The first pulse signal I NHH shown in FIG. 5 (A> is 6
One pulse is removed from each pulse and converted into the second pulse signal INHV shown in FIG. 5(B). Therefore, as shown in FIG. 5(C), the on-screen circuit 6 does not output an on-screen signal in the IH from the removed pulse, but the on-screen signal is output in the next IH to the signal synthesizer 4. is output to. On the other hand, the video signal is present during all horizontal scan periods as shown in FIG.
The signal synthesizer 4 outputs a synthesized video signal shown in FIG. 5(E), and the liquid crystal display panel 1 holds this in an internal sample and hold circuit as shown in FIG. 5(F). It is supplied to each cell indicated by the display position information. Here, since the same display position information is output from the vertical driver circuit 3 in the middle two horizontal scanning periods based on the second pulse signal INHV from which the pulse has been removed, the composite video that has arrived during that period The signals are displayed on the same horizontal scan line.

As is clear from FIG. 5(G), the video signal is displayed in each horizontal scanning line, but the on-screen signal is not displayed in part of the horizontal scanning line. As a result, tooth extraction was displayed, and the characters on the channel display and symbols indicating the volume were difficult to see.

The present invention has been made in consideration of the above points, and provides a flat display that allows characters, symbols, etc. displayed on the screen to be easily seen even in a video signal display mode with a small number of horizontal scanning lines. The aim is to provide equipment.

[Means for Solving the Problems] In order to solve the problems, in the present invention, a flat display device capable of displaying at least two types of video signals having different numbers of horizontal scanning lines is constructed from the following elements.

That is, based on a flat display panel that samples and holds a video signal and captures it into an internal cell for display, and a first pulse signal that indicates the starting position of a horizontal scanning line,
A horizontal driver circuit that forms horizontal display position information for a flat display panel, and outputs a first pulse signal as it is as a second and third pulse signal when instructing a video signal of a method with a small number of horizontal scanning lines; , when a video signal with a large number of horizontal scanning lines is specified, one pulse is removed from every N pulses of the first pulse signal and the second and third pulses are changed according to the difference in the number of horizontal scanning lines. A thinning circuit which forms a pulse signal of 1, and which causes the pulse removal position of the third pulse signal to be earlier than the pulse removal position of the second pulse signal by the delay time associated with the sample and hold operation G in the flat display panel. , a vertical driver circuit that forms vertical display position information of the flat display panel based on the second pulse signal, and a timing based on the vertical synchronization signal and the third pulse signal when the on-screen mode is selected. It consists of an on-screen circuit that outputs an on-screen signal, and a signal synthesizer that combines this on-screen signal with a video signal and provides it to a flat display panel.

[Function] In the present invention, the flat display panel samples and holds the video signal given from the signal synthesizer while displaying cells according to the horizontal display position information from the horizontal driver circuit and the vertical display position information from the vertical driver circuit. and display it.

Here, in the on-screen mode, the signal synthesizer superimposes the on-screen signal from the on-screen circuit onto the video signal and provides it to the flat display panel. Further, the horizontal driver circuit and the vertical driver circuit form horizontal display position information and vertical display position information based on the first and second pulse signals, respectively.

The above is the basic configuration, and a thinning circuit is provided to enable display of two types of video signals.

The thinning circuit outputs the first pulse signal as it is as second and third pulse signals when instructing a video signal of a method with a small number of horizontal scanning lines, and outputs the first pulse signal as is as a second and third pulse signal when instructing a video signal of a method with a large number of horizontal scanning lines. Sometimes, one pulse is removed from every N pulses of the first pulse signal to form second and third pulse signals, depending on the difference in the number of horizontal scan lines. At this time, the pulse removal position of the third pulse signal is made to be earlier than the pulse removal position of the second pulse signal by the delay time associated with the sample and hold operation in the flat display panel. Since the vertical display position information is formed based on the second pulse signal formed by such thinning processing, both types of video signals can be displayed. Further, since the on-screen circuit controls the on-screen display position based on the third pulse signal formed by the thinning process, the on-screen signal can be displayed without missing any part.

[Example] Hereinafter, an example in which the present invention is applied to a liquid crystal television receiver will be described in detail with reference to the drawings.

FIG. 1 shows this embodiment, and corresponding parts to those in FIG. 4 are given the same reference numerals.

This embodiment differs from the conventional device in the configuration of the thinning circuit and in the pulse signals given from the thinning circuit to the vertical driver circuit and on-screen circuit.

Therefore, the basic display configuration is the same as the conventional one.

In FIG. 1, horizontal display position information is given to the liquid crystal display panel 1 from a horizontal driver circuit 82, and
Vertical display position information is given from the vertical driver circuit 3, and the liquid crystal display panel 1 holds the video signal from the signal synthesizer 4 and writes it into the cell of the designated display position information for display.

The horizontal driver circuit 2 receives the incoming first pulse signal IN.
Horizontal display position information is formed in synchronization with HH and output to the liquid crystal display panel 1. The vertical driver circuit 3 receives a second pulse signal INHVI from the thinning circuit 10.
Vertical display position information is formed in synchronization with and output to the liquid crystal display panel 1.

The thinning circuit 10 is supplied with a first pulse signal INHH and a method command signal P/N. When the system command signal P/N indicates the NTSC system, the thinning circuit 10 directly outputs the incoming first pulse signal INHH as second and third pulse signals INHV1 and INHV2 to the corresponding vertical driver circuits. Output to #13 and on-screen episode #I6.

On the other hand, in the thinning circuit 10, the method command signal P/N is PAL.
When instructing the method, the second and third pulse signals INHV formed by the built-in circuit shown in FIG.
I and INHV2 are output to the corresponding vertical driver circuit 3 and on-screen circuit 6.

FIG. 2 shows only the processing configuration within the interrogation circuit 10 when the PAL system is selected.

As shown in this figure, it consists of a hexadecimal counter circuit 11 and a decoding circuit 12. A first pulse signal 1NHH is applied to the clock input terminal of the hexadecimal power counter circuit 11, and it counts up from 0 to 5 every time this pulse arrives. The count value from this counter circuit 11 is given to a decoding circuit 12.

The decoding circuit 12 generates a spike-like pulse every time the count value changes, but does not generate a spike-like pulse when the count value changes to "4" and sends a second pulse signal INHV to the vertical driver circuit 3. form yu. Further, the decoding circuit 12 generates a spike-like pulse every time the count value changes, but when the count value changes to "3", it does not generate a spike-like pulse and sends a third pulse to the on-screen circuit 6. A signal INHV2 is formed.

Further, the decoding circuit 12 resets the counter circuit 11 when the current count reaches "5". In this way, the thinning circuit IW810 outputs the first pulse signal INH
Second and third pulse signals INHVI and INHV2, in which one pulse is removed from every six H pulses, are formed and output.

The on-screen circuit 6 and signal synthesizer 4 have the same configuration as conventional ones. The on-screen circuit 6 receives an on-screen command ON, a vertical synchronization signal VD, and a third pulse signal I.
NHV2 is given.

After receiving the vertical synchronization signal VD, the on-screen circuit 6 counts the third pulse signal INHV2 and outputs an on-screen signal at a timing based on this count value. As a result, the display position and size of on-screen characters, etc. are made equal in both the NTSC system and the PAL system.

FIG. 3 shows a timing chart of each part when the PAL system of this embodiment is selected, and the display operation will be explained using this chart.

The first pulse signal INHH shown in FIG.
The second pulse signal INHV1 shown in Figures <B) and (C)
and INHV2.

Here, the pulses of the third pulse signal INHV2 are removed earlier by IH than the second pulse signal INHV1.

Therefore, as shown in FIG. 3 (D>), the on-screen circuit 6 does not output an on-screen signal during one horizontal scanning period from the removed pulse, but outputs an on-screen signal during the next horizontal scanning period. is output to the signal synthesizer 4. On the other hand, as shown in FIG. 3(E), the video signal is
Given in all horizontal scanning periods. In this way, the signal synthesizer 4 outputs the composite video signal shown in FIG. 3(F), and the liquid crystal display panel 1 outputs the synthesized video signal as shown in FIG. 3(G).
After holding this in the internal sample and hold circuit,
It is supplied to each cell indicated by the display position information.

Here, the same display position information is output from the vertical driver circuit 3 in the middle two horizontal scanning periods based on the second pulse signal INHV1 shown in FIG. 3(B) from which the pulse has been removed. , the composite video signals arriving during that period are displayed on the same horizontal scan line.

In this embodiment, the pulse removal positions of the second pulse signal I NHVl and the third pulse signal INHV2 are made to differ by IH, so that the original video signal and Both on-screen signals are displayed on each horizontal scan line.

Therefore, in the above embodiment, the PA to which the thinning process is applied
Even when an on-screen signal is superimposed and displayed on an L-format video signal, it is possible to realize an easy-to-see display without any missing teeth or the like.

In the above embodiment, the present invention is applied to a liquid crystal television receiver, but it can also be applied to a device that displays video signals of multiple systems with different numbers of horizontal scanning lines, and does not have a tuner section. It may be something. Further, the flat display device is not limited to the above-mentioned liquid crystal display device, but can be applied to a flat display device such as an EL display device.

Furthermore, television systems with different numbers of horizontal scanning lines have N
The present invention is not limited to the combination of the TSC system and the PAL system, and may be two types of high-definition television systems with different numbers of horizontal scanning lines, which are currently under consideration.

[Effects of the Invention] As described above, according to the present invention, when displaying a video signal with a large number of horizontal scanning lines, the flat display panel samples and holds the video signal on which the on-screen signal is superimposed and displays it in each cell. Since the pulse removal timing of the pulse signal applied to the vertical driver circuit and the on-screen circuit is shifted by the delay time associated with the supply operation, it is possible to realize an easy-to-see image without any gaps in the display of the on-screen signal.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of a flat display device according to the present invention, Fig. 2 is a detailed configuration diagram of its main parts, Fig. 3 is a timing chart of each part of the above embodiment, and Fig. 4 is a conventional device. FIG. 5 is a block diagram showing the timing chart of each part. 1...Liquid crystal display panel, 2...Horizontal driver circuit,
3... Vertical driver circuit, 4... Signal combiner, 6.
...On-screen circuit, 10... Thinning circuit.

Claims (1)

[Claims] A flat display device capable of displaying video signals of at least two different formats with different numbers of horizontal scanning lines, including a flat display panel that samples and holds a video signal and captures it in an internal cell for display; a horizontal driver circuit that forms horizontal display position information for the flat display panel based on a first pulse signal representing a line start position; In addition to outputting the pulse signal as it is as the second and third pulse signals, when instructing a video signal of a system with a large number of horizontal scanning lines, the pulse signal is output every N of the first pulse signal according to the difference in the number of horizontal scanning lines. Remove one pulse from the pulse of
and forming a third pulse signal, and furthermore, the pulse removal position of the third pulse signal is made to be earlier than the pulse removal position of the second pulse signal by a delay time associated with a sample and hold operation in the flat display panel. a thinning circuit; a vertical driver circuit that forms vertical display position information of the flat display panel based on the second pulse signal; and a vertical synchronizing signal and a third pulse signal when the on-screen mode is selected. 1. A flat display device comprising: an on-screen circuit that outputs an on-screen signal at a timing based on the above; and a signal synthesizer that combines the on-screen signal with a video signal and provides the synthesized signal to the flat display panel.