JPH06236161A - Display device for color picture - Google Patents

Abstract

PURPOSE:To provide a display device for a color picture which can compensates brightness of the display device for a color picture with a cell unit and with a element unit based on brightness compensation data. CONSTITUTION:This display device for a color picture is provided with a cell which is constituted with dots consisting of elements to which plural red, green and blue fluorescent materials are applied, assembled plurally at upper and lower parts, and a grid electrode for controlling quantity of a beam with which elements are irradiated. Further the device is provided with a first storage means 4 which stores compensation data of pulse width modulation for every element, a means 2 which adds compensation data to picture data inputted to the display device for a color picture and performs pulse width modulation in every element a second storage means 4 which stores bias voltage deciding voltage applied to the grid electrode as a digital signal, and a D/A conversion means 3 which converts bias voltage stored in the second storing means 4 to an analog signal.

Description

Detailed Description of the Invention

[0001]

The present invention is suitable for use in correcting the brightness of a color image display device.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram of a large color image display device. As shown in FIG. 6, the large-sized color image display device is composed of units 100 arranged in an m × n matrix. The unit 100 is composed of, for example, three cells 101 arranged vertically and four cells horizontally arranged as shown in FIG. As shown in FIG. 8, the cell 101 is normally composed of two dots 102 arranged vertically and four dots horizontally, and the dots 102 are B (BLUE), R (RED), and G.
Element 10 coated with each phosphor of (GREEN)
It consists of three.

Unit 1 of the large-sized color image device described above.
While the cell 101 of No. 00 is used up, the phosphor of the element 103 is deteriorated due to aging and secular change, resulting in variation in luminance among the units 100, and it was necessary to correct the luminance level during use. . Therefore, conventionally, in order to correct the luminance, the bias voltage to the cell 101 is changed by a mechanical volume provided on the back surface of the unit 100.

[0004]

As described above, conventionally, the brightness of the cell 101 is corrected by changing the bias voltage to the cell 101 by the mechanical volume control. However, the brightness correction is performed for each cell 101. Therefore, the variation in the brightness between the elements 103 cannot be corrected, and the uniformity of the screen cannot be said to be good. In addition, since mechanical volume is prone to secular change,
There was a problem that the bias voltage would change over time.

Therefore, an object of the present invention is to provide a color image display device capable of correcting the brightness of the color image display device on a cell-by-cell and element-by-element basis based on the brightness correction data.

[0006]

According to the present invention, a color image having a cell composed of a plurality of dots each composed of a plurality of elements coated with a plurality of red, green and blue phosphors is provided. In the display device, for correcting pulse width modulation for each element, the first storage means for storing correction data for pulse width modulation, and for adding pulse width modulation for each element to the image data input to the color image display device. And a driving unit for the color image display device.

Further, according to the present invention, the above-mentioned problem is solved by the present invention. A cell composed of a plurality of dots composed of a plurality of red, green, and blue phosphor-coated elements and a beam amount irradiated to the element. In a color image display device having a grid electrode for controlling the voltage, a bias voltage for determining a voltage to be applied to the grid electrode is stored as a digital signal for each cell, and the second storage means is provided. And a D / A conversion unit for converting the bias voltage stored in the storage unit into an analog signal.

[0008]

FIG. 1 shows the brightness correction by controlling the G ₁ bias voltage of the cell 101 and the PWM for each element 103.
The color image display device is capable of performing both correction and brightness correction by control.

Nonvolatile memory EEPROM 4 shown in FIG.
The brightness correction data pulse-width-modulated for each element and the bias voltage applied to the G ₁ electrode (grid voltage) in cell units are stored as digital signals.
The signal processing unit 1 transmits a bias voltage in cell units to the D / A converter 3, where the bias voltage is analog-converted and applied to the cell 101 as a G ₁ bias voltage. Therefore, the brightness can be adjusted for each cell by the G ₁ bias voltage applied to the cell 101.

On the other hand, the signal processing section 1 sends the image signal and the brightness correction data in element units to a PWM modulator 2 as a driving means. Since the PWM modulator 2 drives the element by the PWM signal in which the brightness correction data is added to the image signal, the brightness level can be corrected in the unit of element.

Therefore, the brightness adjustment between the cells is mainly performed by the bias voltage, and the variation between the elements in the cell, which cannot be adjusted only by the bias voltage, can be performed by the pulse width modulation, so that the entire screen and the cells are uniform. Brightness can be adjusted.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a unit 1 according to an embodiment of the present invention.
It is a block diagram in 00. As shown in FIG. 1, this large-screen-oriented color image display device processes 8-bit image signals and brightness correction data input from an image processing device (not shown) provided outside the unit 100. An EEPROM 4 (Electric) that stores the brightness correction data in units of the signal processing unit 1, the cell 101 and the element 103.
ally Erasable Programmable ROM), a predetermined bit in a cell unit, for example, a D / A converter 3 for D / A converting the G ₁ bias voltage, which is 8-bit brightness correction data in a cell 101 unit, a predetermined bit in an element 103 unit, for example, 5 bits. Add brightness correction data to the 8-bit image signal
A PWM modulator 2 and a cell 101 that create bit-brightness data and pulse-width modulate (PWM) the brightness data.
Are provided respectively.

FIG. 2 is a block diagram of the PWM modulator 2. As shown in FIG. 2, a data bus 5, a cell 1 for inputting an 8-bit image signal and 5-bit brightness correction data.
Address bus 6 for inputting addresses of 01 and element 103, correction data storage RAM 7 for storing 5-bit brightness correction data, 5-bit brightness correction data is added to 8-bit image data, and 13-bit The PWM modulator 2 is configured by the multiplier 8 for creating the brightness data and the PWM converter 10 for converting the 13-bit brightness data into the PWM signal. These operations will be described later.

FIG. 3 is a diagram showing an electrode configuration of the cell 101 and its drive system. The cathode electrode 20 is of a direct heating type, and an AC voltage is applied thereto, and an electron beam (arrow) is emitted. The inverter 26 provided in the field switch 25 alternately applies to the cathode electrode 20 to the upper dot (dot group) 102 and the lower dot (dot group) 102. A voltage determined by the G ₁ bias voltage output from the D / A converter 3 is applied to the G ₁ electrodes (first grid electrodes) 21 arranged above and below, respectively. On the other hand, the PW output by the PWM converter 10 is connected to the base of the transistor Q connected to the G ₁ electrode 21.
The M signal is input. G ₂ electrode (second grid electrode) 2
B, R, and G switching signals for controlling light emission of B, G, and R are input to 2 in units of elements. G ₃ electrode (3rd
The grid electrode) 23 prevents the influence of the electric field generated by the anode electrode 24 from affecting the G ₁ electrode 21, and at the same time appropriately diffuses the flow of electrons to make the electron beam B,
Control is performed so that the entire R and G elements 103 are evenly hit. The electron beam is accelerated by the anode electrode 24, and the electron beam collides with the element 103 to emit light.

The method of controlling the brightness of the cell 101 described above includes a method of controlling the voltage value itself of the G ₁ bias voltage,
There is a method of controlling the application time of the G ₁ bias voltage (PWM control). Therefore, the PWM control is performed by the element 103
In this method, the longer the light emission time, the brighter the human eye looks. Therefore, the brightness can be adjusted by controlling the light emission time. In this method, the light emission time and the brightness level change linearly.

Further, the G ₁ bias voltage control is performed by the G ₁ electrode 2
Since the voltage itself applied to 1 is controlled, the amount of electron beam emitted from the cathode electrode 20 is controlled and the brightness level is adjusted.

The brightness correction processing of the present invention will be described below.

First, when the power of the unit 100 is turned on, the signal processing unit 1 sequentially reads the 5-bit PWM correction data stored in the EEPROM 4, the PWM correction data to the data bus 5 and the address to the address bus 6. Send. The bus line corresponding to the specified address of the address bus 6 is enabled, and the correction data storage R
The PWM correction data is written in the address area of AM7.

Next, an 8-bit digital image signal and an address signal indicating its output destination (cell unit) are input to the signal processing unit 1 from an image processing device (not shown).
The signal processing unit 1 reads the G ₁ bias voltage of the 8-bit cell 101 unit stored in the EEPROM 4, and the D / A
Transmit to converter 3. Converts the G ₁ bias voltage to a predetermined voltage 256 by the D / A converter 3, and outputs a G ₁ a bias voltage.

The signal processor 1 also sends a digital image signal to the data bus 5 and an address signal to the address bus 6. The digital image signal input to the data bus 5 is input to the multiplier 8.

On the other hand, the address input to the address bus 6 enables the address line of the correction data storage RAM 7, and the PWM correction data corresponding to the address is read out and input to the multiplier 8.

The multiplier 8 multiplies the 8-bit digital image signal and the 5-bit brightness correction data to create 13-bit brightness data and outputs it to the PWM converter 10.

The brightness data input to the PWM converter 10 is stored in a register (not shown) designated by the address input to the address bus 6. Also, a counter (not shown) for counting the number of pulses for pulse width modulation is provided corresponding to this register, and the contents of this counter and the register are compared. If they do not match, a pulse is created by the control signal and the transistor is generated. This pulse is applied to the base of Q, and the content of the counter is incremented by "1", for example. Pulses are created and applied as a PWM signal to the base of transistor Q until the contents of the counter match the contents of the register. In this way, 2 ¹³
Since a bit image signal is pulse-width modulated, a 256-level (8-bit) digital video signal input from an image processing device and a PWM signal of a 13-bit brightness level obtained by multiplying 5-bit brightness correction data are transistors. The G ₁ bias voltage output from the D / A converter 3 is applied to the G ₁ electrode 21 for the duration of the pulse width of the PWM signal.

On the other hand, the 8-bit G ₁ bias voltage is D / A
It is D / A converted by the converter 3 and converted into a predetermined voltage value. Since the converted voltage is applied as the G ₁ bias voltage shown in FIG. 3, the brightness can be corrected in units of cells 101 by setting the 8-bit G ₁ bias voltage to a desired value.

As described above, the PWM control and the G ₁ bias control can be independently performed by the PWM modulator 2 and the D / A converter 3.

Next, control of light emission of the element 103 will be described. FIG. 4 is a timing chart for explaining control of light emission of the element 103.

A pulse having a predetermined cycle is input to the field switch 25, the signal input by the inverter 26 is inverted, and the bases of the lower transistor T1 and the upper transistor T2 of the field switch 25 are alternately arranged. A high voltage is applied to the cathode electrodes 20 to heat them.

Since the B, R, G switching signals applied to the G ₂ electrode 22 are signals obtained by dividing one field into three as shown in FIG. 4, the acceleration of the electron beam emitted from the cathode electrode 20 is accelerated. It is controlled in units of B, R, and G elements.

Further, the B, R and G switching signals are set to 255 × 31.
The PWM signal is applied to the base electrode of the transistor T by using the time divided into 7905 as the minimum pulse width of the PWM signal, and the PWM signal is output to the G ₁ electrode 21 by the D / A converter 3 during the time when the PWM signal is output. G ₁ bias voltage is applied, and the B, R, and G elements 103 sequentially emit light.

Next, a processing flow for creating the brightness correction data will be described. FIG. 5 is a flow chart of luminance correction data creation processing.

First, the cell 101 in the unit 100 is caused to emit light, and its brightness is measured (step 50). Based on the measured brightness, it is determined whether correction is necessary (step 51). The brightness is corrected by increasing or decreasing the G ₁ bias voltage for each cell 101 (step 53),
The brightness is measured in units of cells 101 (step 50).

If it is not necessary to correct the measured luminance, the G ₁ bias voltage is stored in the EEPROM 4 (step 52).

Next, the brightness is measured for each element 103 (step 54). It is determined whether brightness correction is necessary (step 55). If it is necessary to correct the brightness, the PWM pulse width is changed for each element 103 to correct the brightness (step 57), and the element 1 is corrected with the corrected brightness.
03 is emitted to measure the brightness (step 54).

Element 1 is used if no brightness correction is required.
The PWM brightness correction data in units of 03 is stored in the EEPROM 4 (step 56). It is determined whether or not the brightness correction of all the elements is completed (step 58), and if not completed, the process proceeds to step 54, and the brightness is corrected in units of the elements 103.

According to the above-described method, first, a large variation in each cell 101 is brightness-corrected by the bias voltage control, and then a fine variation in the cell 101 is P.
Brightness can be corrected by WM control. Further, since the cell bias voltage control and the brightness correction by the element PWM control can be independently performed, the screen brightness can be adjusted by only the bias voltage control or the PWM control.

[0037]

As described above, the brightness correction by controlling the bias voltage in the cell unit and the brightness correction by the control in the element unit can be independently performed, and since these are digital systems, the brightness can be easily adjusted. Corrections can be made. In particular, when both the brightness correction by the bias voltage control in the cell unit and the brightness correction by the PWM control in the element unit are used together, a large variation in the brightness in each cell is corrected by the bias voltage control, and a small variation in the cell is obtained. Since the brightness can be corrected by the PWM control, the correction can be performed in the element unit and the cell unit, and a color image display device with good uniformity can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram of a unit according to an embodiment.

FIG. 2 is a configuration diagram of a PWM modulator 2.

FIG. 3 is a diagram showing an electrode of a cell 101 and its driving system.

FIG. 4 is a diagram showing a timing chart.

FIG. 5 is a diagram showing a processing flow for creating brightness correction data.

FIG. 6 is a configuration diagram of a large color image display device.

7 is a configuration diagram of a unit 100. FIG.

FIG. 8 is a configuration diagram of a cell 101.

[Explanation of symbols]

 1 Signal Processor 2 PWM Modulator 3 D / A Converter 4 EEPROM 5 Data Bus 6 Address Bus 7 Correction Data Storage RAM 8 Multiplier 10 PWM Converter

Claims (5)

[Claims] 1. A color image display device having a cell composed of a plurality of dots each composed of a plurality of elements coated with a plurality of red, green and blue phosphors, wherein pulse width modulation is corrected for each element. A first storage unit for storing data, and a driving unit for adding the correction data to the image data input to the color image display device and performing pulse width modulation for each element. Color image display device. 2. A cell composed of a plurality of dots composed of elements coated with a plurality of red, green, and blue phosphors, and a grid electrode for controlling the beam amount irradiated to the elements. In a color image display device including: a second storage unit that stores, as a digital signal, a bias voltage that determines a voltage applied to the grid electrode for each cell, and the storage unit stores the bias voltage in the second storage unit. A color image display device comprising: a D / A conversion unit for converting a bias voltage into an analog signal. 3. A cell composed of a plurality of dots each composed of an element coated with a plurality of red, green, and blue phosphors, and a grid electrode for controlling the beam amount irradiated to the element. In a color image display device having: a first storage means for storing correction data for pulse width modulation for each element; and a pulse for each element by adding the correction data to image data input to the color image display device. Driving means for width modulation, a second storage means for storing, as a digital signal, a bias voltage for determining a voltage applied to the grid electrode for each cell, and a second storage means stored in the second storage means. A color image display device, comprising: a D / A conversion means for converting the bias voltage into an analog signal. 4. The color image display device according to claim 1, wherein the first storage means is non-volatile. 5. The color image display device according to claim 1, wherein the second storage means is non-volatile.