JPH05323901A - Display device - Google Patents

Abstract

PURPOSE:To obtain a light-shade image with a good contrast by converting the brightness level of inputted gradation data into a brightness level which is proportional to (n)th power, and driving and turning ON a light emitting diode at the illumination rate of the level. CONSTITUTION:The brightness level of the inputted gradation data is converted into the brightness level which is proportional to the (n)th power and the light emitting diode is driven and turned ON at the illumination rate of the level. In this case, a gradation data converting circuit 4 which inputs the gradation data previously processed to four bits and the output data of a 16- frequencydividing circuit 1 uses a synchronizing signal VS as a reset signal and outputs 16 kind of pulse signals Pn. The pulse signals Pn are determined by the frequency of output in a pulse period of an illumination pulse signal Pn so as to become equal to the numeral of a specific output brightness level BOOT, and a pulse signal of one cycle of 16 frequency division corresponding to the pulse period is outputted. A display panel 6 ANDs pulse signals outputted by an illumination pulse generating circuit 3 and the gradation data converting circuit 4 to drive the light emitting diode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device for displaying multi-step halftones on a display panel having light emitting diodes formed in a matrix.

[0002]

2. Description of the Related Art Conventionally, a display device for displaying multi-step halftones on a display panel in which light emitting diodes are formed in a matrix form turns on the light emitting diodes at a lighting rate according to the brightness level of input gradation data. Had control.

[0003]

By the way, in general, human sense of brightness is proportional to the 1/3 power or logarithm of the brightness, and the brightness of the cathode ray tube is proportional to the 2.5 to 3 power of the applied voltage. .. Therefore, in the cathode ray tube, the luminance characteristics of the cathode ray tube and the human sense almost cancel each other out, so that a good display can be obtained without correcting the input data. On the other hand, when gradation display is performed on the light emitting diode type display panel by the conventional method, the gradation difference is unclear and the display lacks in contrast. The present invention has been made to solve such problems, and an object of the present invention is to provide a display device having a good contrast in displaying multi-step halftones on a display panel in which light emitting diodes are arranged in a matrix. is there.

[0004]

In order to solve such problems, the present invention is applied to a display device for displaying multi-step halftones on a display panel in which light emitting diodes are arranged in a matrix. The brightness level of the gradation data is n
The light emitting diode is converted into a brightness level proportional to the power and the light emitting diode is driven to light at a lighting rate according to the brightness level.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. In the embodiment, 16-gradation data obtained by processing the input gradation data into 4 bits is used. FIG. 1 is a block diagram of the display device, and FIG. 2 is an output waveform of each circuit in FIG. Table 1 shows the brightness level Bin for the input 4-bit gradation data, the brightness level Bout obtained by correcting the brightness level Bin, and the number of times the lighting pulse is output, which will be described later. The corrected brightness level Bout is a number. 1
It is calculated from the calculation formula shown in.

[0006]

[Table 1]

[0007]

[Equation 1]

In FIG. 1, reference numeral 1 denotes a 16-divider circuit which receives a synchronizing signal VS and a clock signal CK as a synchronizing signal VS.
Is divided by 16 as a reset signal and a 4-bit pulse signal is output. Reference numeral 2 is a 256 frequency divider circuit that also receives the synchronization signal VS and the clock signal CK as input.
Is divided by 256 as a reset signal and an 8-bit pulse signal is output. Reference numeral 3 is a lighting pulse generation circuit which receives the outputs of the frequency dividing circuits 1 and 2 as an input, and is composed of 16 pulses by combining the 4-bit data and 8-bit data output from the frequency dividing circuits 1 and 2. The pulse signal MCK is output. The lighting pulse signal MCK has different pulse widths, and when one cycle of 256 division is T, the pulse period T, 4T, 9T, 16 is calculated every 1 cycle of 16 division.
16 lighting pulses of T, 16T, ..., 16T are formed.

Reference numeral 4 denotes a gradation data conversion circuit which receives the gradation data preprocessed to 4 bits and the output data of the 16-divider circuit 1 as input, and 16 kinds of pulse signals Pn (Pn (P ₀ , P ₁ , ..., P ₁₅ ) are output. This pulse signal Pn (P ₀ , P ₁ , ..., P ₁₅ ) is equal to the numerical value of the output brightness level Bout shown in Table 1, and the pulse periods T, 4T, 9 of the lighting pulse signal MCK are set.
It is determined by the number of times T, 16T is output, and a pulse signal for one cycle of 16 division corresponding to the corresponding pulse period T, 4T, 9T, 16T is output. Reference numeral 5 is a drive circuit that receives the pulse signal output from the lighting pulse generation circuit 3 and the gradation data conversion circuit 4, and 6 is a display panel in which light emitting diodes are arranged in a matrix. The logical product of the pulse signals output from the conversion circuit 4 is obtained, and the light emitting diode is driven to light by a known method during the period blackened in FIG.

[0010]

The present invention is configured as described above, and converts the brightness level of the input gradation data into a brightness level proportional to the n-th power, and drives the light emitting diode to light at a lighting rate according to the brightness level. By doing so, the gradation difference becomes clear, and a bright and dark image with good contrast can be realized.

[Brief description of drawings]

FIG. 1 is an overall configuration block diagram of a display device that is an embodiment of the present invention.

FIG. 2 is an output waveform diagram of each circuit in FIG.

[Explanation of symbols]

 1 16 frequency dividing circuit 2 256 frequency dividing circuit 3 lighting pulse generating circuit 4 gradation data converting circuit 5 drive circuit 6 display panel

Claims (1)

[Claims] 1. In a display device for displaying multi-step halftones on a display panel in which light emitting diodes are arranged in a matrix, the brightness level of input gradation data is n.
A display device characterized by converting to a brightness level proportional to a power and driving a light emitting diode to light at a lighting rate according to the brightness level.