JP3483953B2 - Multi-tone display device and multi-tone display method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-gradation display device and a multi-gradation display method.
N each having a predetermined weight of display brightness (N: 2 or more
The present invention relates to an improvement in an apparatus and method for displaying a one-frame screen by combining a plurality of display screens.

In recent years, plasma displays (hereinafter simply referred to as P
In the case of a DP device), a liquid crystal display panel, an electroluminescence device, a fluorescent display tube, a light emitting diode, and the like, gradation expression has become indispensable as the display contents are diversified and diversified. When gradation display is performed on such a display device, there is a method of forming a one-frame display screen by combining N display screens having different display brightness weights. In order to express this gradation, a power supply control circuit that supplies a driver with a drive voltage that is the center of the drive voltage range of each display screen is required. In the conventional display device, each drive of N display screens is required. A drive voltage obtained by averaging the center potential of the voltage range is adopted.

However, when the drive voltage range of the display screen common to N sheets shifts the optimum drive voltage value for each display screen depending on the number of light emission of the display panel and its display function,
It becomes narrower than the drive voltage range centered on the drive voltage of one display screen, and the brightness adjustment range for each display screen is limited, which causes deterioration of display quality. Therefore, by devising the method of supplying the drive voltage for expressing the gradation, the center potential of the drive voltage range which is deviated for each display screen is corrected, and the drive voltage range of the total display screen is ensured wide. A device and a method capable of improving the quality and the yield are desired.

[0004]

2. Description of the Related Art FIGS. 4 and 5 are explanatory views according to a conventional example. 4 is a configuration diagram of a power supply control circuit of a multi-gradation display device according to a conventional example, and FIG. 5A is a configuration diagram of a display screen in one frame for explaining a multi-gradation control method. (B)
FIG. 6 is a diagram illustrating a drive voltage range of the total display screen, which is the problem.

For example, the predetermined weight of the display brightness is
A power supply control circuit that supplies a drive voltage Va to an address driver of a PDP device that displays a one-frame screen by combining N (N: a natural number of 2 or more) display screens,
As shown in FIG. 4, resistors R1 and R2, an output transistor 1, a voltage adjusting circuit 2 and a smoothing circuit 3 are provided. In the PDP device, one pixel has three electrodes, discharge is maintained between the two electrodes, and information is written in the third electrode.
Multi-gradation display is performed.

The function of the power supply control circuit is that the power supply voltage VBB
When the reference voltage VR divided by the resistors R1 and R2 is supplied to the voltage adjusting circuit 2, the output transistor 1 is operated by the voltage adjusting circuit 2 according to the reference voltage VR and the drive voltage Va fed back from the output point. Output controlled. The voltage output from the output transistor 1 is smoothed by the smoothing circuit 3, and the drive voltage Va at the output point is the reference voltage V.
It is fixed to a value proportional to R.

As a result, the power supply control circuit causes the PDP to
The fixed drive voltage Va is supplied to the address driver of the device. The drive voltage Va is set, for example, by superimposing the drive voltage ranges forming the N display screens and setting the center potential (average value) as an optimum value. Next, a multi-gradation display method to which the power supply control circuit is applied will be described.
For example, as shown in FIG. 5A, a multi-gradation display method in which N display screens having different display brightness weights are combined to display one frame of a screen in a divided manner is as shown in FIG. The value is 2 ⁰ = 1 when the weight is “0”. The display brightness value of the second display screen is 2 ¹ = 2 when the weight is “1”, and similarly, the display brightness value of the third display screen is 2 ² = 4 when the weight is “2”. Yes, the display luminance value of the Nth display screen is 2 ^{N when the} weight is “N”.

By combining the first display screen to the Nth display screen, multi-gradation display can be performed. The order at this time is arbitrary, and the weighting of the display brightness on each display screen is also an arbitrary value. Table 1 shows specific combinations.

[0009]

[Table 1]

For example, when forming a display screen with a display brightness value = 3, the first and third display screens are combined. When forming a display screen with a display brightness value = 7, the first, second and third display screens are combined. This realizes multi-gradation display in which the screen of one frame is divided and displayed.

[0011]

By the way, according to the conventional multi-gradation display device, a power supply control circuit for supplying the drive voltage Va to the driver in a fixed manner is provided.
Is an average of the center potentials in the respective drive voltage ranges of the N display screens. Therefore, the drive voltage range VX of the display screen (total display screen) common to N sheets is narrower than the drive voltage range centered on the drive voltage Va of one display screen. As a result, the drive voltage range VX of the total display screen is narrowed, so that the brightness adjustment range and the adjustment range of the drive voltage Va in the total display screen are limited, which hinders improvement in display quality. In addition, there are problems that the drive voltage Va is precisely adjusted and the yield of the display device is reduced.

That is, in the diagram for explaining the drive voltage range of N display screens as shown in FIG. 5B, in this method, there are a drive voltage range and an optimum drive voltage value for each of the N display screens. To do. If the optimum drive voltage value is the same for each display screen, no problem will occur even if the drive voltage Va is fixedly supplied. However, as in the case of the first and second display screens, the optimum drive voltage value shifts to the lower region at the boundary of the drive voltage Va, and in the case of the N-1th and Nth display screens, the optimum drive voltage value is changed. In some cases, the voltage value shifts to the upper region with the drive voltage Va as the boundary. Such a shift of the optimum drive voltage value occurs because the internal impedance changes and the discharge conditions change depending on the number of times the display panel emits light and its display function.

If the optimum driving voltage value shifts to the lower region, the brightness of the first and second display screens cannot be adjusted sufficiently, or the optimum driving voltage value shifts to the upper region. This means that the brightness of the N-1 or Nth display screen cannot be adjusted sufficiently. The larger the shift amount, the narrower the drive voltage range VX of the total display screen, and the lower the drive voltage range of the display device.

According to the conventional power supply control circuit, the drive voltage Va can be fixedly supplied based on the reference voltage VR divided by the resistors R1 and R2. However, in the conventional power supply control circuit, the drive voltage range V of the total display screen is
Stay tuned for X. The present invention was created in view of the problems of the conventional example, and devises a method of supplying a drive voltage for gradation expression to correct the center potential of a drive voltage range that is deviated for each display screen. An object of the present invention is to provide a multi-gradation display device and a multi-gradation display method capable of ensuring a wide drive voltage range of the total display screen and improving display quality and yield.

[0015]

According to the present invention SUMMARY OF THE INVENTION The multi-gray scale display device, the embodiments as shown in FIGS. 1 to 3, it
N having a predetermined weight of display luminance is: display the screen of one frame by combining the (N 2 or greater natural <br/> number) pieces of the display screen
In multi-gradation display apparatus which indicates, and write information to the pixel
Address driver 16 (first driver) for
The power supply voltage Va is variable in single display screen each, wherein said power control means 100 is supplied to the address driver 16 a variable voltage Vb1~VbN as schematically central potential of the driving voltage range is provided.

In the multi-gradation display device of the present invention, the power supply control means 100 stores a voltage correction value assigned to each of N display screens, as shown in FIG.
1, a voltage value readout circuit 12 for reading out a voltage correction value corresponding to each of the N display screens, a D / A conversion circuit 13 for converting the voltage correction value into a digital signal and an analog signal,
The power supply circuit 14 that outputs the drive voltages Vb1 to VbN by varying the power supply voltage Va based on the analog voltage value from the A / A conversion circuit 13, and the output control of the voltage value read circuit 12 based on the display information and the display control signal. And a screen rewriting control circuit 15 for performing the following.

The multi-gradation display device of the present invention further comprises a second driver 17 for selecting the pixel electrode, and a display panel 18 having a plurality of the pixel electrodes . According to the multi-gradation display method of the present invention, the predetermined weight of the display brightness is set, respectively.
Combining N (N: a natural number of 2 or more) display screens
In addition to the multi-gradation display method that displays a 1-frame screen
The power supply voltage Va is changed for each of the N display screens,
Supply to address driver 16 for writing information to the source
It is characterized by doing. Furthermore, this multi-gradation display method
Then , the voltage correction value is acquired in advance for each of the N display screens,
Based on the acquired voltage correction value, the power supply voltage Va
Was correct the deviation of the central potential of the driving voltage range by varying the A on the basis of the corrected drive voltage range
It is characterized by driving the dress driver 16 .

In the multi-gradation display method of the present invention, the voltage correction value is obtained by obtaining a difference between drive voltages of two adjacent screens among N display screens, thereby achieving the above object. .

[0019]

[Operation] Next, referring to FIGS. 1 (A) and 1 (B),
The operation of the multi-gradation display device of the present invention will be described. The power supply voltage Va according to the voltage correction value assigned to each of the N display screens.
Is changed by the power supply control means 100. The variable voltages Vb1 to VbN are output from the power supply control means 100 as the center potential (optimum drive voltage) of the drive voltage range for adjusting the brightness of the display screen.

Therefore, when N (N: natural number) display screens having different display brightness weights are combined to display one frame of the screen in a divided manner, the number of times the display panel emits light and its display function are unwilling. The center potential of the displaced drive voltage range can be corrected for each display screen by the optimum drive voltages Vb1 to VbN. Specifically, as shown in FIG. 1A, when the display information and the display control signal are supplied to the screen rewriting control circuit 15 in the power supply control means 100, the screen rewriting control circuit 15 causes the voltage value reading circuit 12 to operate. Through this, the voltage correction value corresponding to each of the N display screens is read from the storage circuit 11. This voltage correction value is, for example, N
Among the display screens of one sheet, the difference in drive voltage between two adjacent screens is acquired in advance, and this difference is stored in the storage circuit 11.

When the voltage correction value is transferred from the voltage value reading circuit 12 to the D / A conversion circuit 13, the correction value is digital-analog converted. This analog voltage value is D / A
It is output from the conversion circuit 13 to the power supply circuit 14, and the power supply circuit 14 varies the power supply voltage Va based on the analog voltage value. The voltage varied here is the driving voltage Vb1 to Vb
As bN, the first driver 1 as shown in FIG.
6 is supplied.

With this, the center potential of the drive voltage range can be corrected for each display screen by the optimum drive voltages Vb1 to VbN, and wherever the first to Nth display screens are taken,
The optimum drive voltage value can be set at the center of the drive voltage range. Also, a display screen common to N sheets (total display screen)
Drive voltage range of 1 display screen can be made almost equal to the drive voltage range of one display screen, the drive voltage range of the total display screen can be secured wider than the conventional example, and the display quality and the yield can be improved. Can be achieved.

Further, according to the multi-gradation display device of the present invention,
On the other hand, the pixel electrode of the display panel 18 is the second driver 1
On the other hand, the information is written in the pixel electrode by the first driver 16 based on the drive voltages Vb1 to VN from the power supply control means 100. At this time, the weight of the display luminance is fully adjusted using the drive voltage range centered on each of the optimum drive voltages Vb1 to VbN of the N display screens (the multi-gradation display method of the present invention).

Therefore, the weight of the display brightness can be adjusted by fully using the drive voltage range in which the deviation of the center potential is corrected by the voltage correction value acquired for each of the N display screens. The adjusted display brightness is different N
By combining (N: a natural number of 2 or more) display screens, one frame screen can be divided and displayed in high definition.

As a result, it is possible to improve the display quality as compared with the conventional example, and it is possible to reduce the defects of the display device due to the reduction of the drive voltage range, and to improve the production yield of the display device. Can be improved.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, each embodiment of the present invention will be described with reference to the drawings. 1 to 3 are diagrams for explaining a multi-gradation display device and a multi-gradation display method according to an embodiment of the present invention. FIG. 1A is an overall configuration diagram of a power supply control circuit according to an embodiment of the present invention, and FIG. 1B is a configuration diagram of a multi-gradation display device using the same. FIG. 2 is an internal configuration diagram of the power supply circuit of the power supply control circuit, and FIG. 3 is a diagram for explaining the drive voltage range of the total display screen related to the multi-gradation display.

For example, the power supply control means 100 applicable to a PDP device which combines N (N: natural number) display screens having different display brightness weights to display one frame of a screen is shown in FIG. In addition, the memory circuit 11, the voltage value reading circuit 12, the D / A conversion circuit 13, and the power supply circuit 14
And a screen rewriting control circuit 15. That is, the memory circuit 11 stores the voltage correction value V assigned to each of the N display screens.
It stores ε. A programmable read-only memory such as PROM or EPROM is used for the storage circuit 11. As the voltage correction value Vε, an optimum drive voltage value is measured in advance for each display screen, and the resultant value is stored as a binary digital value. For example, as the voltage correction value Vε, the difference between the drive voltages of two adjacent screens among the N display screens is acquired.

The voltage value read circuit (hereinafter, simply referred to as a read circuit) 12 has, for example, N in response to a read control signal SR.
The voltage correction value Vε commensurate with each display screen is read out. The D / A conversion circuit 13 digital-analog converts the voltage correction value Vε and outputs the analog voltage value VE to the power supply circuit 14. The power supply circuit 14 changes the power supply voltage Va based on the analog voltage value VE from the D / A conversion circuit 13 and outputs the drive voltages Vb1 to VbN. For example, as shown in FIG. 2, the power supply circuit 14 includes a reference voltage circuit 41, comparators 42 and 44, an oscillation circuit 43, and an FE.
T driver circuit 45, n-type field effect transistor 4
6, a choke coil 47, a protection diode 48, and an electric field capacitor 49.

The reference voltage circuit 41 outputs the reference voltage VREF to the comparator 42. The comparator 42 uses the analog voltage value VE from the D / A conversion circuit 13 and the reference voltage circuit 4
The reference voltage VREF from 1 is compared and the comparison result voltage VC suitable for each display screen is output to the comparator 44.
Specifically, the comparator 42 lowers the voltage VC when the analog voltage value VE is lower than the reference voltage VREF. When the analog voltage value VE is higher than the reference voltage VREF, the voltage VC is increased. The oscillator circuit 43 outputs a signal of the oscillation frequency Sf to the comparator 44.

The comparator 44 outputs the driver control voltage VF to the FET driver circuit 45 on the basis of the N comparison result voltages VC which are different for each display screen and the signal of the oscillation frequency f. The driver circuit 45 generates a gate control signal SG according to the control voltage VF and supplies it to the gate of the transistor 46. The transistor 46 performs an ON / OFF operation on the basis of the gate control signals SG having N pulse widths which are different for each display screen to lower the power supply voltage Va. Choke coil 47, protection diode 48 and electric field capacitor 4
Reference numeral 9 smoothes and outputs the lowered drive voltages Vb1 to VbN.

Returning to FIG. 1A, the screen rewriting control circuit (hereinafter simply referred to as control circuit) 15 controls the output of the reading circuit 12 based on the display information and the display control signal. For example, the control circuit 15 generates the read control signal SR based on the video display data DIN for writing information in the pixel electrode and the vertical synchronizing signal SV that defines the display period of one frame, and outputs it to the read circuit 12.

As a result, the power supply control means 100 changes the power supply voltage Va according to the voltage correction value Vε assigned to each of the N display screens, and adjusts the changed voltages Vb1 to VbN to the brightness of the display screen. It can be output as the center potential of the driving voltage range. Next, a multi-gradation display device to which the power supply control means 100 according to the embodiment of the present invention is applied will be described. For example, a PDP device which is an example of a multi-gradation display device includes an address driver 16, an XY driver 17, a plasma display panel (PDP) 18 and a power supply control means 100 in FIG.

The address driver 16 is an example of a first driver, and the driving voltage Vb1 to Vb1 from the power supply control means 100 is used.
Information is written in the pixel electrode based on VbN.
The XY driver 17 is an example of a second driver and selects a pixel electrode. Plasma display panel (P
DP) 18 is an example of a display panel, in which one pixel has three electrodes, discharge is maintained between the two electrodes, and information is written to the third electrode to perform multi-gradation display. is there.

Next, with reference to FIGS. 1 to 3, the operation of the display device of the present invention will be described with respect to the multi-gradation display method according to the embodiment of the present invention. For example, when N (N: natural number) display screens having different display luminance weights are combined to display one frame of the screen in a divided manner, based on the voltage correction value Vε acquired in advance for each of the N display screens. The deviation of the center potential of the drive voltage range is corrected, and the weight of the display brightness is adjusted based on this drive voltage range.

That is, the power supply control means 100 varies the power supply voltage Va according to the voltage correction value Vε assigned to each of the N display screens. This variable voltage Vb1 to Vb
N is output as the center potential (optimal drive voltage) of the drive voltage range for adjusting the brightness of the display screen as shown in FIG. In FIG. 3, the vertical axis represents the drive voltage value V and the horizontal axis represents the time t, which indicates one frame period. Vbi,
[I = 1 to N] is an optimum drive voltage value.

Specifically, the power supply control means 100 is shown in FIG.
As shown in (A), when the screen display rewriting control circuit 15 is supplied with the video display data DIN and the vertical synchronizing signal SV, the control circuit 15 causes the storage circuit 11 via the reading circuit 12.
From, the voltage correction value Vε commensurate with each of the N display screens is read out. When the voltage correction value Vε is transferred from the reading circuit 12 to the D / A conversion circuit 13, the correction value is digital-analog converted in the circuit 13. This analog voltage value V
E is output from the D / A conversion circuit 13 to the power supply circuit 14,
In the power supply circuit 14, the power supply voltage Va is changed based on the analog voltage value VE. The voltage changed here is supplied to the address driver 16 as shown in FIG. 1B as the optimum driving voltages Vb1 to VbN.

The pixel electrode of the display panel 18 is selected by the XY driver 17, while information is written in the pixel electrode by the address driver 16 based on the driving voltages Vb1 to VN from the power supply control means 100. At this time, N
Optimal drive voltages Vb1 to VbN for each display screen
The weight of the display brightness is fully adjusted by using the drive voltage range centered on.

In this way, according to the multi-gradation display device according to the embodiment of the present invention, as shown in FIG. 1B, the power supply control means 100, the address driver 16, the XY driver 17 and the display. The panel 18 is provided, and the power supply voltage Va is varied by the control means 100 according to the voltage correction value Vε assigned to each of the N display screens.
VbN is output to the address driver 16 as the center potential of the drive voltage range of each display screen.

Therefore, the center potential of the drive voltage range that is unintentionally shifted depending on the number of times of light emission of the display panel 18 and its display function can be corrected for each display screen by the optimum drive voltages Vb1 to VbN. The address driver 16 can adjust the weight of the display brightness based on the corrected drive voltage range, and the display brightness weighted by fully using the drive voltage range can be adjusted to N (N: a natural number). By combining the display screens of 1), a 1-frame screen can be divided and displayed in high definition.

As a result, as shown in FIG. 3, the drive voltage range of the display screen (total display screen) common to N sheets can be made almost equal to the drive voltage range of one display screen,
It is possible to secure a wider drive voltage range of the total display screen and relax the specifications of the power supply circuit 14 as compared with the conventional example. Also, by mounting the power supply control circuit in the display device, it is possible to adjust the difference in the optimum voltage range between the display devices for each display device, and to relax the specifications when using the display device. Contribute.

Further, it is possible to improve the display quality as compared with the conventional example, and it is possible to reduce the defects of the display device due to the reduction of the drive voltage range, and to improve the production yield of the display device. Can be achieved. In the embodiments of the present invention, the case of the PDP device has been described, but it is also possible to use a display panel such as a liquid crystal display panel, electroluminescence, a fluorescent display tube and a light emitting diode, and combine the power supply control circuit of the present invention. , A similar effect is obtained.

[0042]

As described above, according to the multi-gradation display device of the present invention, the power supply voltage is varied according to the voltage correction value assigned to each of the N display screens, and the varied voltage is applied. Is provided as a center potential of a drive voltage range for adjusting the brightness of the display screen.

For this reason, when N display screens having different display brightness weights are combined to display one frame of the screen in a divided manner, the drive voltage range is unintentionally shifted depending on the number of times the display panel emits light and its display function. The center potential of can be corrected for each display screen from the optimum drive voltage. Further, the drive voltage range of the total display screen can be made almost equal to the drive voltage range of one display screen, and the drive voltage range of the total display screen can be secured wider than that of the conventional example.

According to the multi-gradation display device of the present invention,
A driver for writing information in the pixel electrode based on the drive voltage from the power supply control means is provided. Therefore, the weight of the display luminance can be adjusted by fully using the drive voltage range in which the shift of the center potential of the N display screens is corrected, and the N display screens having the weight adjusted can be combined. As a result, a 1-frame screen can be divided and displayed in high definition.

This greatly contributes to providing a high-quality and high-quality multi-gradation display device and improving the production yield thereof.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a power supply control unit and a multi-gradation display device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a power supply circuit according to an embodiment of the present invention.

FIG. 3 is a voltage range diagram illustrating a multi-gradation display according to an embodiment of the present invention.

FIG. 4 is a configuration diagram of a power supply control circuit of a display device according to a conventional example.

FIG. 5 is a voltage range diagram illustrating multi-gradation control according to a conventional example and its problems.

[Explanation of symbols]

100… power control means, 11 ... memory circuit, 12 ... Voltage reading circuit, 13 ... D / A conversion circuit, 14 ... power supply circuit, 15 ... Screen rewriting control circuit, 16 ... First driver (address driver), 17 ... Second driver (X-Y driver), 18 ... Display panel, DIN ... video display data, SV ... Vertical sync signal, VREF ... reference voltage, Vε ... voltage correction value, VE ... analog voltage value, Vbi, [i = 1 to N] ... Optimal drive voltage value, SR ... Read control signal.

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Claims (5)

(57) [Claims] 1. Each has a predetermined weight of display brightness
In a multi-gradation display device that displays N (N: a natural number of 2 or more ) display screens to display a 1-frame screen , an address driver for writing information to pixels, and a power supply voltage for each N display screens. the Va variably, the add said variable voltage as a schematic central potential of the driving voltage range
Multi-gradation display device characterized by power control means for supplying the less the driver is provided. 2. The power supply control means stores a voltage correction value assigned to each of N display screens;
A readout circuit for reading out a voltage correction value suitable for each of the display screens, a conversion circuit for converting the voltage correction value into a digital / analog signal, and a drive voltage by varying the power supply voltage based on the analog voltage value from the conversion circuit. Output power circuit,
The multi-gradation display device according to claim 1, further comprising a control circuit that controls the output of the readout circuit based on display information and a display control signal. 3. Each has a predetermined weight of display brightness
Combining N (N: 2 or more natural number) display screens
In the multi-gradation display method for displaying a 1-frame screen , the power supply voltage Va is changed for each N display screens to change the information to pixels.
To supply the address driver for writing
Characteristic multi-gradation display method. 4. A voltage correction value is previously acquired for each of N display screens, and the power supply is based on the acquired voltage correction value.
The deviation of the central potential of the drive voltage range is corrected by varying the voltages Va, and drives the address driver based on the corrected drive voltage range 請
The multi-gradation display method according to claim 3 . 5. The multi-gradation display method according to claim 4, wherein the voltage correction value obtains a difference between drive voltages of two adjacent screens among N display screens.