JPH05333831A - Gradational display control circuit - Google Patents

Abstract

PURPOSE:To suppress the generation of a moving phenomenon on a display device with multi-gradational display ability by converting gradation data according to random number data and displaying the data. CONSTITUTION:This gradational display control circuit consists of a frame buffer 2 stored with display gradations, a frame buffer writing means 1 for writing the gradation data, a display readout part 4 for reading the gradation data out of the frame buffer 2, a random number generation part 5 for generating random number data, dot by dot, and a data comparison part 6 which compares the gradation data with the random number data generated by the random number generation part 5; and the data are displayed according to the output result of the data comparison part 6, so the generation of the moving phenomenon is small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gradation display control circuit for displaying and converting gradation data based on random number data in a display device having multi-gradation display capability.

[0002]

2. Description of the Related Art Conventionally, as a display method having a multi-gradation display capability, FRC (FrameRateCon) has generally been used.
The control method and the spatial method are known, and a method of obtaining a double effect by using these two methods together is also known.

The FRC system is shown as a "gradation display control circuit" in JP-A-2-79092, and the spatial system is shown as "a liquid crystal display element and a spatial modulation element" in JP-A-2-230119. In Japanese Patent Laid-Open No. 3-118596, a method of using both is described as a "gradation display control method".

[0004]

Among the above methods, FR
In the method using both the C method and the spatial method, when an attempt is made to represent a halftone in a wide range of the display device, the FRC is set in a unit pixel of spatial modulation (a pixel using a plurality of pixels of the display device). Since the display phase of the display changes simultaneously in a wide range of halftone areas of the display device, a moving phenomenon in which the display as a group of unit pixels of the spatial modulation appears to move in a wavy manner may occur. Display 1991, pp. 176-179.

This moving phenomenon is perceived as "flicker" on the screen, resulting in deterioration of display quality. As a method of coping with such "flicker", a solution for LCD is considered in JP-A-2-993, from claim 2 of "LCD gradation display device". In this method, the unit pixel for spatial modulation is made into a larger "combined block", and the "flicker" of the screen is suppressed by devising the arrangement of this "combined block". This method brings about the complexity of the circuit called "joint block" management, and the moving phenomenon in a large unit called "joint block"
Although weakened, it never disappears.

Now, the moving phenomenon will be described with reference to FIG. In a black and white 2-gradation display device,
When an expression of 1/3 luminance is to be performed, by displaying each pattern of pattern 1, pattern 2 and pattern 3 as shown in FIG. 4A as 1 → 2 → 3 → 1 for each field. The display pattern is the FRC method. When the display is performed in a wide range of 9 × 9, this 1/3 luminance expression has a display pattern as shown in FIG. 4B, and a human-like expression such as a dotted line is obtained. Visible This phenomenon is called the moving phenomenon, which seems to move while the field changes.

[0007]

The present invention is intended to solve these problems, and in a gradation display control circuit for controlling the gradation of a display image in a dot matrix display panel, gradation data is stored. A frame buffer, and reading means for reading the display data stored in the frame buffer for each dot unit,
Random number generating means for generating a random number in synchronization with the reading means, and a data comparing section for comparing the gradation data for each dot unit read by the reading means with the random number data generated by the random number generating means. Consists of and
Provided is a gradation display control circuit in which display data is gradation-converted based on output data from the data comparison unit.

[0008]

According to this structure, the gradation data read from the frame buffer storing the gradation data for each dot unit by the reading unit and the random number generated by the random number generator in synchronization with the reading unit. While the data is compared with the data by the data comparison unit, the original gradation data is converted and displayed based on the random number data, so that it is possible to realize multi-gradation by adding a simple circuit. The moving phenomenon that occurs as an aggregate of pixels does not appear.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a block diagram of a gradation display control circuit showing an embodiment of the present invention, and FIG. 2 is a display pattern diagram displayed using the gradation display control circuit showing an embodiment of the present invention. FIG. 3 is a diagram showing random number data generated from a random number generator used in the gradation display control circuit according to the embodiment of the present invention, and FIG. 4 is an explanatory diagram for explaining the moving phenomenon.

In FIG. 1, the gradation display control circuit of the present invention comprises a display device 8, a frame buffer 2 in which a display gradation for each dot which is a display unit is stored, and a gradation in the frame buffer 2. In accordance with a frame buffer writing unit 1 for writing data and a display read instruction from the display control unit 3, read control is performed on the frame buffer 2 in which grayscale data is stored,
Based on the read control, the display reading unit 4 for reading the gradation data from the frame buffer 2, the random number generating unit 5 for generating the random number data for each field and each dot, and the display reading unit 4 Based on the comparison result output from the data comparison unit 6 that compares the read grayscale data and the random number data generated by the random number generation unit 5 with each other, the data for the display device is obtained. Data assembling unit 7 for assembling and display reading unit 4
And a display control unit 3 for generating a synchronizing signal for the display device 8.

An operation of a method for displaying four gradations in a pseudo manner in a display device capable of expressing only two colors of black and white will be described with reference to FIGS.

A display screen to be displayed on the display device 8 is generated from the frame buffer writing means 1 shown in FIG. 1, and gradation data is written in the frame buffer 2 at any time. The display control unit 3 instructs the display reading unit 4 to read the data to be displayed from the frame buffer 2. Display readout unit 4
Is read out from the frame buffer 2 in accordance with the instruction from the display control unit 3, and the read data is sent as one of the data for comparison by the data comparison unit 6. On the other hand, the random number generator 5 generates a random number of the number corresponding to the number of dots on the screen sent by the display reading unit 4 to the data comparing unit 6, and the random number data has the pattern shown in FIG.
To the other side as comparison data.

The data comparing section 6 compares the data from the display reading section 4 with the data from the random number generating section 5 for each dot unit of the display screen. The compared data is sent to the data assembling unit 7 as data for each dot.

A data comparison method in the data comparison unit 6 will be described with reference to FIG.

As conditions for displaying the data on the display device 8, white is displayed when the data is 1, and black is displayed when the data is 0.
A value of 0 to 3 is set in the frame buffer 2 in order to display four gradations in a pseudo manner in a display device that can express only two colors of black and white. As for the value, 3 is white,
As the value decreases to 2, 1, 0, it becomes black, and at 0, black is displayed. On the other hand, a random number as shown in FIG. 3 is generated for each dot from the random number generation unit 5, and the data read out from the frame buffer 2 by the display reading unit 4 in the data comparison unit 6 for each dot. Be compared. The gradation data read from the frame buffer 2 is compared with the random number data, and when the gradation data is larger than the random number data, 1 is sent to the display device 8 and white is displayed. On the other hand, when the gradation data is smaller than the random number data, 0 is sent to the display device 8 and black is displayed.
The data assembling unit 7 collects the data output from the data comparing unit 6 so that the display unit 8 can receive the data, and sends the data to the display unit 8 for display. Display control unit 3
At, the data assembling unit 7 sends a synchronization signal or the like required for display to the display device at a timing consistent with the timing of sending data to the display device 8. As an application example, red, green,
By applying the present invention to each color in the display device 8 having a display capability of 8 colors in total of 2 gradations for each of blue, it is possible to display 16 or more colors. Also,
Even when the display device 8 has a display capability of two or more gradations, the same display device 8 can realize a display having the display capability or more.

[0016]

As described above, according to the present invention, since the gradation data and the random number data output from the random number generation section are compared by the data comparison section for each dot and then output, a simple circuit is used. Gradation can be realized, and since the intermediate gradation is expressed based on the random number data, the possibility of the moving phenomenon occurring is small.

[Brief description of drawings]

FIG. 1 is a block diagram of a gradation display control circuit showing an embodiment of the present invention.

FIG. 2 is a display pattern diagram displayed by using a gradation display control circuit according to an embodiment of the present invention.

FIG. 3 is a diagram showing random number data generated from a random number generator used in the gradation display control circuit according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram for explaining a moving phenomenon.

[Explanation of symbols]

 1 Frame Buffer Writing Means 2 Frame Buffer 3 Display Control Section 4 Display Reading Section 5 Random Number Generation Section 6 Data Comparison Section 7 Data Assembly Section 8 Display Device

Claims (1)

[Claims] 1. A gradation display control circuit for controlling the gradation of a display image in a dot matrix display panel, wherein a frame buffer storing gradation data and display data stored in the frame buffer are provided for each dot. Read-out means for reading out for each unit, random number generation means for generating a random number in synchronization with the read-out means, gradation data for each dot unit read out by the read-out means, and the random-number generation means A gradation display control circuit, comprising: a data comparison unit that compares the random number data with the random number data, and display data is gradation-converted and displayed based on output data from the data comparison unit.