JPH04247490A - Brightness adjusting circuit of fluorescent display tube - Google Patents

Abstract

PURPOSE:To perform the brightness adjustment of every color in fluorescent display tubes. CONSTITUTION:Voltage adjusting circuits 15, 16 and 17, where the number of circuits is the same as the number of the phospher colors of a fluorescent display tube 1, are switched to supply to a shield electrode 3. Or, the previously determined and stored brightness data in a memory are used by a micro-computer which controls the driving voltage of the shield electrode 3.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a brightness adjustment circuit for a fluorescent display tube.

0002

2. Description of the Related Art FIG. 5 shows a conventional brightness adjustment circuit for a fluorescent display tube. In the figure, 1 is a fluorescent display tube in which red, green, and blue phosphors are arranged in a matrix, 2 is an anode to which a constant high voltage is applied, 3 is a shield electrode that controls the amount of emitted electrons, and 4
5 is an X grid (scanning electrode) to which a scanning signal is applied, 5 is a Y grid (data electrode) to which a phosphor on/off signal is applied, 6 is a filament that emits electrons, and 7 is an X grid 4 for applying a scanning signal. 8 is a drive circuit that supplies on/off signals to Y grid 5; 9 is an X grid controller that generates scanning signals; 10 is a Y grid controller that generates on/off signals; 11 is a drive circuit that supplies drive voltage to R
1, R2 is a resistor for voltage division, 12 is a transistor, V
D is the driving voltage, VH is the high voltage applied to the anode 2, VK
is the filament power supply, and Vf is the filament voltage. Next, the operation will be explained. In the fluorescent display tube 1, electrons emitted from a filament 6 are accelerated by X and Y grids 4 and 5 and collide with an anode 2 to emit light.
Any display can be obtained by controlling the Y grids 4, 5 with drive circuits 7, 8 and controllers 9, 10. Drive circuits 7 and 8 for the X and Y grid electrodes 4 and 5 switch drive voltages VD according to respective control signals and supply them to the X and Y grids. A voltage adjustment circuit consisting of a resistor 11 and a transistor 12 divides the drive voltage VD and applies the shield electrode drive voltage (hereinafter referred to as VS) to the shield electrode 3. Vs=VD×R2/(R1+R2) is supplied. Here, the brightness of the fluorescent display tube 1 is determined by the filament 6 and
, Y grids 4 and 5, and the voltage between the shield electrode 3 and the anode 2. Since the VD supplied to the grid electrodes 4 and 5 and the high voltage VH applied to the anode 2 are constant, the shield The brightness of the fluorescent display tube 1 is adjusted by changing the value of the shield electrode drive voltage VS supplied to the electrode 3.

0003

[Problems to be Solved by the Invention] Since the conventional luminance adjustment circuit for a fluorescent display tube is constructed as described above, the shield electrode drive voltage VS supplied to the shield electrode of one fluorescent display tube can be any voltage. Since the value is fixed, there is a problem in that the brightness cannot be adjusted for each color within the tube. The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a device that allows brightness adjustment for each color in a fluorescent display tube.

0004

[Means for Solving the Problems] A brightness adjustment circuit for a fluorescent display tube according to the invention as set forth in claim 1 is provided with shield electrode drive voltage adjustment circuits of the same number as colors of phosphors, and a controller for controlling the voltage adjustment circuits. In this example, the shield electrode drive voltage is switched in a time-division manner to provide a brightness adjustment circuit for each color. Further, in the brightness adjustment circuit for a fluorescent display tube according to the invention as claimed in claim 2, the drive circuit control microcomputer reads out the set brightness data written in the non-volatile memory and controls the D/A converter based on the brightness data. By switching the generated shield electrode drive voltage in a time division manner,
This is a brightness adjustment circuit for each color.

[0005]

The controller of the brightness adjustment circuit of the fluorescent display tube according to the invention described in claim 1 can adjust the shield electrode drive voltage for each color by switching each voltage adjustment circuit in a time-division manner. The microcomputer for controlling the drive circuit of the brightness adjustment circuit of a fluorescent display tube according to the second aspect of the present invention can control and adjust the shield electrode drive voltage for each color based on the brightness data written in the memory.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the first invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of a brightness adjustment circuit for a fluorescent display tube according to the first invention. In the figure, 13R is a switch circuit for the voltage adjustment circuit for R (red), 13G is a switch circuit for G (green), 13B is a switch circuit for B (blue), 14 is a controller, 15 is a voltage adjustment circuit for R, 16 17 is a voltage adjustment circuit for G, 17 is a voltage adjustment circuit for B, and other devices (numerals 1 to 10) are the same as in the conventional example.

FIG. 2 is a diagram showing the matrix structure of the X grid 4 and Y grid 5 of the fluorescent display tube of the present invention. From the figure, R, G, and B are two-dimensional pixel corresponding areas for each color on the phosphor screen, and
G1-XG8 indicate matrix rows corresponding to each pixel in the eight X grids 4, and YG1 to YG8 indicate matrix columns corresponding to each pixel in the eight Y grids 5. FIG. 3 is a diagram showing the relationship between the waveforms, timings, and display colors of signals applied to each electrode of the fluorescent display tube 1 of the present invention. Each XG1 of X grid 4
- Scanning signal waveform applied to XG8 at time-sharing timing; On/off signal waveform applied to each YG1-YG8 of Y grid 5 at time-sharing timing; VR, VB
, VG are voltage waveforms applied to the shield electrode, and R, B, and G are fluorescent display colors.

Next, the operation will be explained. From FIG. 1, the fluorescent display tube 1 in this case includes three voltage adjustment circuits 15, 16, and 17 for each color of R, G, and B, and each voltage adjustment circuit divides the drive voltage VD into switch circuits 13R, 13G, and 13.
When B is ON, shield electrode drive voltages (VR, VG, VB) for each color are supplied to the shield electrode 3, but this voltage value is not the fixed value VS in the conventional example. The switch circuits 13R, 13G, and 13B are ON/OFF controlled by the controller 14, and are connected to VR, VG, and VB.
One of the three driving voltages is supplied to the shield electrode 3. The controller 14 has voltage adjustment circuits 15, 16, 1
The output of 7 is switched in a time-division manner.The brightness of the fluorescent display tube 1 differs for each color even if the driving voltage VS is constant, so it is necessary to switch the output for each color in this way and apply different voltage values to the shield electrode 3. It is possible to adjust the brightness of each color.

Further, the signal waveform applied to each electrode of the fluorescent display tube 1 and the time-division switching timing of brightness adjustment for each display color will be explained with reference to FIGS. 2 and 3. As shown in Figure 3
A scanning signal with a duty of 1/8 is applied to each of XG1 to XG8 of grid 4 (here, the number of grids is 8 for the sake of explanation), and each of YG1 to YG8 of Y grid 5
The on/off signals for the pixels at the intersections of the X and Y grids are time-divided and applied for each color. In this case, the odd-numbered columns YG1,
YG3, YG5, YG7 and even columns YG2, YG4, Y
G6 and YG8 are applied with a lighting pulse (positive) and a lighting pulse (negative) as a group column. Drive voltages VR, VG, and VB corresponding to each display color are applied to the shield electrode 3 in a time-division manner by the controller 14. be done. now,
Starting from the first R (red) point in the display color sequence as shown in FIG. Supply electrode drive voltage VR. At this point, the X grid 4 is scanning the XG8 area, and the Y grid 5 has odd numbered columns when the light-off signal is applied and even numbered columns when the lighting signal is applied. Therefore, from the matrix structure diagram in Figure 2, XG8 rows, Y even columns, YG2, YG4, YG6
, YG8, the brightness of R (red) is adjusted. Moving on to the operation at the next point, the controller 14 changes to B (blue).
is selected, the voltage adjustment circuit 17 is turned on, and the shield electrode drive voltage VB is supplied to the shield electrode 3. The lights go out. From the matrix of FIG. 2, brightness adjustment of B (blue) is performed in the intersection area of the XG1 row and YG1, YG3, YG5, and YG7.

As described above, the brightness adjustment for each color is performed by the controller 14 in conjunction with the switching timing of the X grid controller 9 and Y grid controller 10 of the fluorescent display tube 1, and the voltage adjustment circuits 15, 16,
By processing the 17 switching timings in a time-division manner, brightness adjustment for each color can be performed.

Next, an embodiment of the second invention will be explained based on the drawings. FIG. 4 is a brightness adjustment circuit diagram of a fluorescent display tube according to the second invention. In the figure, 20 is a drive circuit control computer, 21 is a D/A converter, 22 is a voltage conversion circuit,
23 is a non-volatile memory, and other devices and symbols are the same as in the first embodiment of the invention. Next, the operation will be explained. In the fluorescent display tube 1 shown in FIG. 4, a D/A converter 21 and a voltage conversion circuit 22 are connected to the shield electrode 3. The nonvolatile memory 23 stores set brightness data for adjusting the brightness of the fluorescent display tube 1. This brightness data is data that detects the brightness of each color of the fluorescent display tube 1 and makes the brightness constant for each color. When the power is turned on, the microcomputer 20 reads brightness data from the nonvolatile memory 23, writes it to the RAM in the microcomputer 20, and outputs the written brightness data to the D/A converter 21 according to the brightness of the displayed color. /A converter 2
1 is a voltage conversion circuit 2 that generates a voltage corresponding to brightness data.
2 and time-divisionally applying a shield electrode drive voltage corresponding to the luminance data to the shield electrode 3 for each color, thereby adjusting the luminance for each color.

[0012] Furthermore, the X, Y matrix structure diagram in FIG.
Since the signal timing diagram in FIG. 3 is the same in the case of the second invention, parts that overlap with the explanation of the first invention will be omitted, and the time-sharing diagram of brightness adjustment of each display color in the second invention will be explained. The switching timing will be explained. Now, assuming that the first R (red) in the display color row is the starting point from FIG. A D/A converter 21 that outputs data generates VR corresponding to the luminance data and applies it to the shield electrode through a voltage conversion circuit 22. At this point, the X grid 4 is scanning XG8, and the Y grid 5 has odd-numbered columns when the lights are turned off, and even-numbered columns when the lights are turned on, so in the matrix of FIG. Brightness adjustment of R (red) is performed in the intersection area. Moving to the next point, when the microcomputer 20 selects B (blue) and similarly supplies the drive voltage VB to the shield electrode 3, the X grid 4 is scanning XG1, and the Y grid 5 is scanning an odd number. The columns are when the signal is on, and the even columns are when the signal is off. Therefore, from Figure 2, XG1 row and YG1, YG3, YG5, Y
B (blue) brightness adjustment is performed in the intersection area of column G7.

As described above, the brightness adjustment for each color is performed by the microcomputer 20 using the brightness data in the RAM and the
Grid controller 9 and Y grid controller 10
The timing data is taken in and controlled in a time-division manner, and a driving voltage corresponding to each color is applied to the shield electrode 3, so that brightness can be automatically adjusted for each color.

[0014] Since an actual display device is composed of N fluorescent display tubes, in the case of the first invention there are N stages of voltage adjustment circuit blocks, and in the case of the second invention there are N stages of D/A blocks. Adjustments are made using a converter and voltage conversion circuit.

[0015]

As described above, according to the first invention, the voltage adjustment circuits for the fluorescent display tube shield electrode drive voltage are arranged in the same number as the colors of the phosphors. This has the effect that the brightness can be easily adjusted. According to the second invention, the brightness of the fluorescent display tube is adjusted by storing preset brightness data in the memory.
Since the microcomputer is configured to control the shield electrode drive voltage according to the brightness data, there is an effect that automatic brightness adjustment for each color can be made more precisely and accurately.

[Brief explanation of the drawing]

FIG. 1 is a brightness adjustment circuit for a fluorescent display tube according to an embodiment of the first invention.

FIG. 2 is a matrix structure diagram of an X grid and a Y grid.

FIG. 3 is a diagram showing the relationship between signal waveforms, timings, and display colors applied to each electrode of a fluorescent display tube.

FIG. 4 is a brightness adjustment circuit for a fluorescent display tube according to an embodiment of the second invention.

FIG. 5 is a diagram of a brightness adjustment circuit of a conventional fluorescent display tube.

[Explanation of symbols]

1 Fluorescent display tube 2 Anode 3 Shield electrode 4 X grid 5 Y grid 6 Filament 14 Controller 15 R voltage adjustment circuit 16 G voltage adjustment circuit 17 B voltage adjustment circuit 20 Drive circuit control microcomputer 21
D/A converter 23 Non-volatile memory Note that in the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] [Claim 1] Consisting of an anode coated with phosphors of multiple colors and to which high voltage is applied, a scanning electrode and a data electrode that accelerate electrons emitted from a filament toward the anode and control the light emission of the phosphor. In a fluorescent display tube equipped with a matrix-structured grid electrode and a shield electrode that controls the amount of electron emission, a voltage adjustment circuit for driving the shield electrodes of the same number as the color of the phosphor and a voltage adjustment circuit for driving the shield electrodes are provided. A brightness adjustment circuit for a fluorescent display tube, comprising: a controller for time-division switching; [Claim 2] Consisting of an anode coated with phosphors of multiple colors and to which high voltage is applied, and a scanning electrode and a data electrode that accelerate electrons emitted from a filament toward the anode and control the light emission of the phosphor. In a fluorescent display tube equipped with a matrix-structured grid electrode and a shield electrode that controls the amount of electron emission, a nonvolatile memory in which set brightness data is written, and a D 1. A brightness adjustment circuit for a fluorescent display tube, comprising: a microcomputer that time-divisionally switches the shield electrode drive voltage generated in the /A converter.