JPH09130710A - Liquid crystal display video signal generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the generator and to save space of the generator at a low cost for a superimposed liquid crystal display video signal. SOLUTION: A main video signal from a field memory 4 and a superimposing signal representing a character pattern from a microcomputer 1 are given to a ROM 16 provided with a lookup table for gamma correction and superimposing signals. The input signal is given to a corresponding table in the ROM 16 and its output is used for a display signal of a liquid crystal display panel 8 as a superimposed video signal. A basic clock oscillator 11 supplies a timing clock for the operation of the entire display device.

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 video signal generating device, and more particularly to a device for generating a video signal superimposed on a main video signal and input to liquid crystal display means. Is.

[0002]

2. Description of the Related Art FIG. 4 is a diagram illustrating a conventional input image signal generating apparatus for superimposing and displaying a character or the like on a main image for display. In FIG. 4, the OS
The D data synthesis circuit 9 uses the RG from the field memory 4.
It is a superimposing circuit consisting of 24 2-channel multiplexers for switching between the 24-bit main image data of B and the superimposing data of RGB. The data to be superimposed are R, G, B and blanking (BLK) signals (superimposed characters and background image signals by RGB signals) by a program of a character generator (CG) built in the microcomputer (microcomputer) 1. Is output as a signal for switching between and. The display position and timing of the character to be imposed are determined by the input HSYNC and VSYNC, and the pattern is determined by the R, G, B and BLK signals described above, and the designated character is at the designated position. Will be displayed in.

Therefore, the RGB signal and the BLK signal generated by the microcomputer 1 are input to the OSD data synthesizing circuit 9 via the latch circuit, and the synthesized data is stored in the liquid crystal panel 8 as 24-bit data. It is used for display driving, but before that, gamma (γ) correction is performed in the ROMII10. In ROMII10,
A γ correction table having a look-up table configuration is prepared, and the γ correction table can be selected depending on which of RGB / video display mode is selected. ROMII1
The output of 0 is input to the liquid crystal panel 8 via the latch circuit 7. The clock (25 MHz) from the basic clock oscillator 11 is input to the latch circuits 5 and 7 and the liquid crystal panel 8 as a timing clock, and to the microcomputer 1 and the latch circuit 3 via the 1/2 frequency dividing circuit 2.

As shown in the above example, in a conventional liquid crystal display device for displaying a video signal or an RGB signal from a personal computer, when superimposing information such as character characters is synthesized and displayed on a main image, a microcomputer or the like is used. Superimpose data from the character signal generator is combined with the main image and then γ-corrected, or after the main image is γ-corrected, the superimpose data is combined and displayed on the liquid crystal panel. However, circuit means such as an OSP data synthesizing circuit for synthesizing image data is required.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems in the prior art, and is conventionally prepared as an independent component in a device for generating a superimposed liquid crystal display video signal. It is an object of the present invention to provide a space-saving and low-cost input image signal generation device for liquid crystal image display, by simplifying the circuit means and the γ correction means for synthesizing the image data that have been used.

[0006]

According to a first aspect of the present invention, a memory having a built-in look-up table and input means for inputting a superimpose signal from a main video signal and a pattern generating means such as a character as a digital signal, respectively. In the liquid crystal display video signal generation device having a processing means for performing digital gamma correction by using the look-up table for the video signal from the input means, a superimpose table is built in the memory in addition to the gamma correction table. By using a table of either gamma correction or superimposing corresponding to the input signal from the input means in the processing means, a function of outputting the superimposed composite display video signal is added. Expands the lookup table that has existed for gamma correction in the past Te and makes it possible to output a combined image of the two signals by selectively in response to a main video signal and superimpose the signal.

According to a second aspect of the present invention, in the first aspect of the present invention, the function of the processing means is to perform only gamma correction of the main video signal at a pixel position where the superimpose signal is active, and only to the superimpose signal. To have a function of processing and outputting as a video signal,
The present invention provides means for embodying a process of generating a composite video.

According to a third aspect of the present invention, in the first or second aspect of the invention, the superimpose table includes a correction table for a superimpose signal, and the superimpose signal includes, for example, an RGB signal. Even if given as a binary value, the display video signal imposed by the table processing is adapted to match the main video (video) signal.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an example of an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an outline of the configuration of a liquid crystal image display device including a γ correction circuit including a superimpose function according to the present invention. In addition,
In this embodiment, there are components similar to those of the prior art shown in FIG. 2, and those components are numbered the same so as to refer to the above description of the prior art. In FIG. 1, a character pattern generator 1 composed of a microcomputer or the like is supplied with a clock obtained by dividing the output of the basic clock oscillator 11 by a 1/2 divider circuit 2 and using this as a reference clock for superimposing data. Generate certain RGB and BLK signals. These signals are input to the ROMI 6 through the latch circuit 3.

On the other hand, a video signal (RGB24BIT signal)
Are once written to the field memory 4. This memory is a high-speed FIFO capable of high-speed aperiodic read and write operations.
It is a serial access memory that performs O (First in First Out) operation. After writing, the latch circuit 5 is read at a timing synchronized with the clock of the reference clock oscillator 11.
Is input to ROMI6. At this time, the latch circuit 3
R which is the superimpose data input from
If the GB and BLK (blanking) signals are all "0", the video signal (RGB
24 BIT signal) passes through the gamma (γ) table in the ROMI 6 and is input to the liquid crystal panel 8 via the latch circuit 7.

Here, the ROMI 6 has not only a γ correction table but also a superimpose table built therein, and the table can be selected according to whether the input signal is a video signal or a superimpose signal. Has become. Further, the γ correction table is switched depending on whether the video display signal is a video signal or an RGB signal to a microcomputer. And the latch circuit 3
R which is the superimpose data input from
Either GB or BLK signal is "1" (active)
In the case of, the video signal (RGB
24BIT signal) does not pass through the γ correction table in ROMI6, and the RGB signal (binary) that is the superimpose data input from the latch circuit 3 is ROMI6.
Is input to the liquid crystal panel 8 via the latch circuit 7.

The above operation will be described more specifically with reference to the drawings. FIG. 2 illustrates a ROMI data map. Then, FIG. 3 shows a flowchart of the operation using the data map of FIG. In this example, ROM data having a gray screen is shown, but this can be changed to various display screens such as a display screen when there is no signal (blue screen) or a display screen (gray screen) instead of the lens cap. In the application screen of 1), a signal according to the screen generation is added.

Here, as shown in the flow chart of FIG. 3, first, when the BK screen is processed (step S1) and a BK screen signal is obtained, a video signal for producing the gray screen display screen as described above. Is selected (step S2). In addition, it is detected whether or not the signal which does not require the BK screen processing has the BLK signal (step S3).
/ Which video display mode to choose (step S
The γ correction operation is performed according to 4) (step S5), and the image signal is output.

On the other hand, if the BLK signal is detected in step S3, it is then detected whether or not there is a superimpose signal (step S6). If there is, a signal for each of R, G and B is prepared. If there is no table processing operation (step S7), and if there is no table processing, a video signal is output by setting "R, G, B" to 0 by "black" operation.

[0015]

The method according to the prior art requires a circuit means for synthesizing the superimpose data from a character pattern generator such as a microcomputer with a main image such as a main image such as a video, and then gamma Since the image signal passes through the correction circuit, the device becomes complicated and large and the cost becomes high. However, the present invention is provided with a digital γ correction circuit using a memory such as a ROM as a lookup table. In the liquid crystal image display device, a simple and small size and low cost device is realized by γ-correcting a normal video signal and a personal computer signal and providing a means having a circuit function for superimposing a character signal at the same time. You will be able to do it.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a liquid crystal display image signal generation device of the present invention.

FIG. 2 is a diagram illustrating a ROMI data map as an element of the present invention.

FIG. 3 is a flowchart showing an example of an operation using the ROMI table of the present invention.

FIG. 4 is a block diagram illustrating a conventional superimposed image signal generating apparatus.

[Explanation of symbols]

1 ... Microcomputer, 2 ... 1/2 divider circuit, 3, 5, 7 ... Latch circuit, 4 ... Field memory, 6 ... ROMI, 8 ... Liquid crystal panel, 9 ... OSD data synthesizing circuit, 10 ... ROMI
I, 11 ... Basic clock oscillator, S1 to S8 ... Operation step.

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location H04N 5/445 H04N 5/445 Z

Claims (3)

[Claims] 1. A main video signal and input means for inputting a superimpose signal from a pattern generating means such as a character as a digital signal, a memory having a look-up table built therein, and the look-up table from the input means. In the liquid crystal display video signal generation device including processing means for performing digital gamma correction using the video signal of No. 1, the memory has a built-in superimpose table in addition to the gamma correction table, and the processing means inputs from the input means. Liquid crystal display video signal generation, characterized by adding a function of outputting the superimposed composite display video signal by using either a gamma correction table or a superimpose table corresponding to the signal apparatus. 2. The function of the processing means has a function of processing only the superimpose signal and outputting it as a video signal without gamma correction of the main video signal at the pixel position where the superimpose signal is active. The liquid crystal display image signal generating device according to claim 1, wherein the liquid crystal display image signal generating device is provided. 3. The liquid crystal display video signal generating device according to claim 1, wherein the superimposing table includes a correction table for a superimposing signal.