JP2013097169A - Driving device of display unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that a power loss occurs in a signal line driving section since an excessive voltage is applied to the signal line driving section when necessary voltage drops in accordance with a change in a current value in the case of changing an output current value of the signal line driving section in accordance with video display.SOLUTION: A driving device of a display unit includes a scanning line driving section 6 for driving a scanning line of a display unit 1, a signal line driving section 5 for driving a signal line of the display unit, a drive current control section 8 for changing current outputted from the signal line driving section by video to be displayed on the display unit, and a voltage control section 10 for controlling voltage inputted to the signal line driving section. When current outputted from the signal line driving section 5 by the video to be displayed is changed by the drive current control section 8, the voltage control section 10 changes voltage inputted to the signal line driving section 5 to reduce power consumption.

Description

  The present invention relates to a display unit driving apparatus in which light emitting elements such as organic EL and LEDs are arranged in a matrix.

  A display device is generally composed of a display unit composed of a display panel in which light emitting elements are arranged, and a driving device for driving the light emitting elements. As shown in FIG. 11, the display unit 1 has a plurality of signal lines 2 and a plurality of scanning lines 3, and the pixels of the light-emitting elements 4 arranged in a matrix are arranged at the intersections of the lines. Yes. The driving device includes a signal line driving unit 5 connected to the signal line 2 of the display unit 1, a scanning line driving unit 6 connected to the scanning line 3 of the display unit 1, and a signal line according to input video data. The controller 7 is configured to control the driving unit 5 and the scanning line driving unit 6.

  Video data input from the outside is received by the controller 7, and the controller 7 transmits control signals to the signal line driving unit 5 and the scanning line driving unit 6 in accordance with the video data. The display unit 1 is driven in accordance with control signals output from the controller 7 to the signal line driving unit 5 and the scanning line driving unit 6, and displays an image on the display unit 1.

  Such a display device includes a drive voltage sensor that measures a drive voltage at a specific position that appears on the drive line of the display unit (display), and the voltage controller operates according to the drive voltage measured by the drive voltage sensor. An invention is disclosed in which the power supply voltage of a signal line driving unit having a constant current source for supplying a constant current is controlled to reduce power consumption (see Patent Document 1).

Patent No. 4064400 (FIG. 5 and its description)

  The conventional driving of the display device is basically constant current driving and gradation control with time width, but the current output from the signal line driving unit 5 according to the video data input to the controller 7. The value may be changed. At this time, the output voltage of the signal line driver 5 varies depending on the current value. When the output current value is reduced, the voltage required for driving the light emitting element 4 is reduced, and the output voltage of the signal line driving unit 5 is also reduced. On the other hand, the voltage input to the signal line driving unit 5 is set in accordance with the maximum current of the pulse output from the signal line driving unit 5, so that when the current output from the signal line driving unit 5 decreases, the signal line driving unit 5 increases the difference between the input voltage and the output voltage, resulting in power loss. As a result, power consumption of the display device is deteriorated.

  Further, in the display device of Patent Document 1, since the voltage at a specific position when current is output is measured and fed back to the input voltage, the voltage is actually input after the voltage at the specific position is measured. A delay time occurs until the voltage changes. When the time axis of change of the optimum value of the input voltage is long, such as an increase of the input voltage due to deterioration of the light emitting element or increase in element temperature, there is no problem, but when changing the current value depending on the video display state, etc. When the optimum value of the input voltage changes in a short period, voltage loss or current shortage occurs.

  The present invention has been made to solve the above-described problems, and when the driving current of the light emitting element is changed according to the image to be displayed, the input voltage of the signal line driving unit is also changed. An object of the present invention is to obtain a display unit drive device that improves power consumption.

  The display unit driving device of the present invention has a plurality of scanning lines and a plurality of signal lines, and in the display unit driving device in which pixels of light emitting elements are arranged at intersections of the lines, the scanning lines for driving the scanning lines. A drive unit, a signal line drive unit that drives a signal line, a drive current control unit that changes a current output from the signal line drive unit according to an image displayed on the display unit, and a voltage that is input to the signal line drive unit A voltage control unit, a controller for controlling the scanning line drive unit, the signal line drive unit, the drive current control unit, and the voltage control unit, and a current output from the signal line drive unit according to the video to be displayed is a drive current control unit In this case, the voltage controller changes the voltage input to the signal line driver.

  According to the present invention, for example, when the current output from the signal line driving unit is reduced, the voltage input to the signal line driving unit is small, and when the current output from the signal line driving unit is increased, the signal line driving is performed. Since the voltage input to the signal line drive unit is changed in response to the change in the current output from the signal line drive unit so that the voltage input to the unit is also increased, the power loss is minimized and the power consumption is reduced. Deterioration can be prevented.

It is a block diagram which shows the drive device of the display unit in Embodiment 1 of this invention. It is explanatory drawing of the voltage drop of the drive device in Embodiment 1 of this invention. It is explanatory drawing of the voltage control of the drive device in Embodiment 1 of this invention. It is a block diagram which shows the drive device of the display unit in Embodiment 2 of this invention. It is a block diagram which shows the drive device of the display unit in Embodiment 3 of this invention. It is a block diagram which shows the drive device of the display unit in Embodiment 4 of this invention. It is explanatory drawing which shows the drive device of Embodiment 5 of this invention. It is explanatory drawing of the voltage control of the drive device in Embodiment 5 of this invention. It is a block diagram which shows the drive device of the display unit in Embodiment 6 of this invention. It is explanatory drawing of the voltage control of the drive device in Embodiment 6 of this invention. It is a block diagram which shows the drive device of the conventional display unit.

Embodiment 1 FIG.
Hereinafter, a display unit driving apparatus according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing an example of a driving apparatus of the present invention, and FIGS. 2 and 3 are explanatory diagrams of voltage drop and voltage control of the driving apparatus.
In FIG. 1, the display unit 1 includes a plurality of signal lines 2, a plurality of scanning lines 3, and light emitting elements 4 arranged in a matrix at intersections of the lines. The signal line 2 is connected to the signal line driving unit 5 and the scanning line 3 is connected to the scanning line driving unit 6, and the signal line driving unit 5 and the scanning line driving unit 6 are controlled by a controller 7. Such a configuration is the same as that of the conventional FIG.

  The controller 7 inputs video data from an external video or PC to the control circuit 71, and the control circuit 71 classifies the video data into current data, image data, and scanning data. The current data classified by the control circuit 71 is output to the drive current control unit 8 and the current-voltage conversion unit 9. On the other hand, the image data classified by the control circuit 71 is output to the signal line driving unit 5, and the scanning data classified by the control circuit 71 is output to the scanning line driving unit 6.

  The drive current control unit 8 changes the current value based on the current data and outputs the change to the signal line drive unit 5. The signal line driving unit 5 basically has a current source for constant current driving, performs constant current driving, and performs gradation control for controlling the brightness of a screen displayed with a PWM (pulse width modulation) time width. Is going. However, gradation control may be performed by changing the current value according to the image to be displayed.

  For example, the light emitting element 4 has a characteristic that when the luminance is lowered, the current can be driven more efficiently when the current is lowered than when the time width is lowered. Therefore, when displaying a dark image, it is better to lower the current than the time width. As shown in FIG. 1, since a plurality of signal lines 2 are connected to one drive current control unit 8 having a current changing function, a plurality of signals connected to the drive current control unit 8 when the current is lowered. The brightness of all lines 2 decreases. Therefore, as an example of the driving method, the change in luminance for normal video display is performed by changing the time width, and the current is changed when changing the brightness of the entire screen, such as a change in the brightness setting of the screen. There is a method. Since the light emission luminance of the light emitting element 4 is substantially proportional to the current, when the brightness is reduced by several percent, the drive current may be reduced by a few percent.

The current-voltage conversion unit 9 includes a current-voltage correlation memory 91 and a current data-voltage data conversion unit 92. Based on information in the current-voltage correlation memory 91, the current data-voltage data conversion unit 92 is a controller. The current data output from 7 is converted into voltage data. The voltage data from the current data-voltage data conversion unit 92 is output to the voltage control unit 10, and the voltage control unit 101 of the voltage control unit 10 changes the power supply voltage based on this voltage data, and the voltage output unit 102. To output voltage. The voltage output from the voltage output unit 102 is input to the signal line driving unit 5. That is, the voltage control unit 10 changes the voltage input to the signal line driving unit 5 in response to the current change output from the signal line driving unit 5.
In FIG. 1, the current-voltage conversion unit 9 is described with a configuration different from that of the controller 7, but may be included in the controller 7.

  As described above, the controller 7 transmits a control signal to the signal line driving unit 5, the scanning line driving unit 6, and the driving current control unit 8 according to the video data, and the signal line driving unit 5 has a current corresponding to the image data. The signal line 2 is driven, and the scanning line driving unit 6 drives the scanning line 3 according to the scanning data. At the same time, the voltage controller 10 controls the input voltage of the signal line driver 5 to be optimal according to the current value output from the signal line driver 5. By these operations, the light emitting element 4 in the display unit 1 is driven to perform image display.

The voltage required for driving the light emitting element 4 at this time will be described with reference to FIG. When the signal line driving unit 5 outputs the current I ₁ based on the image data transmitted from the controller 7, the current I ₁ flows through the light emitting element 4 to the scanning line driving unit 6.
Here, the resistance component between the scanning line driving unit 6 and the light emitting element 4 is R ₁ , the resistance between the light emitting element 4 and the signal line driving unit 5 is R _2, and the voltage drop of the R ₁ part is V ₁ and R ₂ part. Is V ₂ , the voltage drop of the light emitting element 4 is V ₃ , and the voltage drop of the signal line driver 5 is V ₄ , the voltage V _{5 of the} power supply line necessary to output the current I ₁ is V ₁ + V ₂ + V ₃ + V ₄

When the current I ₁ is reduced according to the image data, V ₁ , V ₂ , V ₃ , V ₄ are reduced according to the decrease amount of the current, and as a result, a power supply line necessary for outputting the current I ₁ voltage _{V 5} also becomes small. If the voltage V ₅ is not changed even if the current I ₁ is reduced, a voltage higher than the necessary voltage is input to the signal line driver 5, and the voltage drop V ₄ of the signal line driver 5 is necessary. It becomes larger than above, resulting in power loss. Therefore, when changing the current I ₁ in accordance with an image to be displayed controls the voltage control unit 10 by the controller 7 so that the voltage of the power supply line is changed.

FIG. 3 shows the relationship between the input voltage and the output current value of the signal line driver 5 when the driving method of the present invention is used. When the current value output from the signal line driving unit 5 decreases from I ₂ to I ₃ , the voltage control unit 10 controls the power supply voltage accordingly, and the input voltage input to the signal line driving unit 5 is also from V ₆ to V Reduce to ₇ . Conversely, when the current value output from the signal line driver 5 increases from I ₃ to I ₂ , the voltage controller 10 controls the power supply voltage accordingly, and the input voltage input to the signal line driver 5 is also V as high as _{V 6} from _7. In this way, the input voltage of the signal line driving unit 5 is controlled to be optimal according to the current value output from the signal line driving unit 5, and the power loss can be minimized.

  As described above, according to the first embodiment, in the display device that displays the image by modulating the drive current and the drive time, the drive current control unit 8 outputs the current output from the signal line drive unit 5 according to the display to be imaged. When the voltage control unit 10 reduces the voltage input to the signal line driving unit 5 when the voltage control unit 10 reduces the voltage, and the current output from the signal line driving unit 5 increases, the voltage control unit 10 By performing control so that the voltage input to 5 is also increased, it is possible to minimize power loss in the signal line driving unit 5 and reduce power consumption.

Embodiment 2. FIG.
Next, a display unit driving apparatus according to Embodiment 2 of the present invention will be described with reference to FIG.
The invention of the second embodiment is such that the current output from the signal line driving unit 5 and the voltage input to the signal line driving unit 5 are individually controlled for each color of the RGB signal in the driving device of the first embodiment. Is.

In FIG. 4, the signal line driving unit 5 is connected to the signal line 2 of the display unit 1 by an R (red) signal line driving unit 5R, a G (green) signal line driving unit 5G, and a B (blue) signal line driving unit 5B. Three are connected. Between the R signal line drive unit 5R and the controller 7, an R voltage control unit 10R and an R drive current control unit 8R are connected. Similarly, a G voltage controller 10G and a G drive current controller 8G are connected between the G signal line driver 5G and the controller 7. A B voltage control unit 10B and a B drive current control unit 8B are connected between the B signal line drive unit 5B and the controller 7.
In FIG. 4, the current-voltage conversion unit 9 is built in the controller 7. Further, the scanning line driving unit 6 is omitted.

  Also in the second embodiment, when the current output from the individual signal line driving units 5R, 5G, and 5B of the RGB signals is reduced according to the display to be imaged, the voltage control units 10R, 10G, and 10B are reduced. By controlling the voltage input to the signal line drive units 5R, 5G, and 5B to be small, it is possible to minimize power loss and reduce power consumption.

Embodiment 3 FIG.
Next, a display unit driving apparatus according to Embodiment 3 of the present invention will be described with reference to FIG.
In the invention of the third embodiment, one display device is constituted by a plurality of display units, a signal line driving unit is provided for each display unit, and the voltage output from the voltage control unit is a plurality of signal lines. The power supply line voltage input to the drive unit and output from the voltage control unit is controlled so as to be optimized according to the current values output from the plurality of signal line drive units.

  5, the display unit 1 is configured such that a plurality of display units 1a, 1b,... 1n are arranged adjacent to each other to form one display device. Signal line drivers 5a, 5b,... 5n are connected to the signal lines 2 of the display units 1a, 1b,. A signal from one drive current control unit 8 and a voltage from one voltage control unit 10 are input to each signal line drive unit 5a, 5b,. The controller 7 incorporating the current-voltage conversion unit 9 sends control signals to the signal line drive units 5a, 5b,... 5n, the drive current control unit 8 and the voltage control unit 10. In FIG. 5, the scanning line driving unit 6 is omitted.

  With such a configuration, when the current output from the signal line drive units 5a, 5b,... 5n is changed by the drive current control unit 8 depending on the video to be displayed, the voltage control unit 10 responds to the change in the current with a signal. The voltage input to the line driving units 5a, 5b,. Thus, by controlling the voltage of the power supply line output from the voltage control unit 10 to be optimal according to the current values output from the plurality of signal line driving units 5a, 5b,. Reduction of power consumption can be realized.

Embodiment 4 FIG.
Next, a display unit driving apparatus according to Embodiment 4 of the present invention will be described with reference to FIG.
In the invention of the fourth embodiment, one display device is constituted by a plurality of display units, a signal line driving unit is provided for each display unit, and a plurality of voltage control units are also provided corresponding to each signal line driving unit. It is provided.

  In FIG. 6, the display unit 1 includes a plurality of display units 1 a 1 to 1 am, 1 b 1 to 1 bm,... 1 n 1 to 1 nm arranged adjacent to each other vertically and horizontally to constitute one display device. . Signal line driving units 5 (not shown) are connected to the signal lines of the display units 1a1 to 1am, 1b1 to 1bm,. A voltage controller 10a is connected to each signal line driver 5 corresponding to the display units 1a1 to 1am, and a voltage controller 10b is connected to each signal line driver 5 corresponding to the display units 1b1 to 1bm. A voltage control unit 10n is connected to each signal line driving unit 5 corresponding to the display units 1n1 to 1nm.

  Each signal line driver 5 is supplied with voltages from a plurality of voltage controllers 10a, 10b,. The controller 7 having a built-in current-voltage conversion unit sends control signals to the voltage control units 10a, 10b,. In FIG. 6, the signal line driving unit 5, the scanning line driving unit 6, and the driving current control unit 8 are omitted.

  In the case of the configuration of the fourth embodiment, the distance between the voltage control units 10a, 10b,... 10n and the signal line driving unit 5 depends on the arrangement positions of the display units 1a1 to 1am, 1b1 to 1bm,. Longer voltage drop may occur. In that case, when the distance between the voltage control units 10a, 10b,... 10n and the signal line driving unit 5 is long, it is necessary to increase the voltage output from the voltage control units 10a, 10b,. is there. Therefore, when the distance between the voltage control units 10a, 10b,.

  In this way, when a plurality of display units are combined into one screen, the voltage control unit 10 determines the voltage to be input to the signal line driving unit 5 for each display unit depending on the video displayed on the display unit and the position of the display unit. Individual control is performed to minimize power loss and reduce power consumption.

Embodiment 5 FIG.
Next, a display unit driving apparatus according to Embodiment 5 of the present invention will be described with reference to FIGS.
According to the fifth embodiment of the present invention, the voltage input to the signal line drive unit is adjusted during the drive period of the scan line according to the position of the scan line to be driven among the plurality of scan lines in the display unit. It is a thing.

As shown in FIG. 7, display elements 4 ₁ , 4 ₂ ,... 4 _n composed of a plurality of organic EL elements are connected between the signal line driving unit 5 and the scanning line driving unit 6. When the resistances between the four elements are R ₃₁ , R ₃₂ ,..., R _3n , a voltage difference is generated in the voltage required to drive the display element 4 ₁ and the display element 4 _n with the current I _4. The difference ΔVs is expressed by I ₄ × (R ₃₂ + R ₃₃ +... + R _3n ). That is, as the scanning line is further away from the signal line driving unit 5, the voltage drop becomes larger, so that a voltage difference is generated between the scanning lines. When this voltage difference occurs, the brightness varies depending on the position of the screen, resulting in color unevenness.

In the present invention, in order to eliminate the voltage difference generated between the driving scan lines, the voltage input to the signal line driving unit 5 is changed by the voltage control unit 10 in accordance with the driving scan line, and the voltage difference between the scan lines is changed. Prevent it from occurring. FIG. 8 shows the waveform of the input voltage during driving when the current I ₄ is output from the signal line driving unit 5.
Scan lines display element 4 ₁ is connected 3 _1, display element 4 ₂ connected scan line 3 _2, the signal line driving unit when ... display element 4 _n drives the connected scan line 3 _n 5 is gradually increased as the scanning line 3 is further away from the signal line driving unit 5 so that the input voltage of V 5 becomes V ₉₁ , V _{92 ,.} Here, V _{9k + 1} = V _{9k + 1} + I ₄ × R _k (1 ≦ K ≦ n−1) holds.

Embodiment 6 FIG.
Next, a display unit driving apparatus according to Embodiment 6 of the present invention will be described with reference to FIG.
In the first to fifth embodiments, the driving method in which the input voltage is changed according to the current value output from the signal line driving unit 5 has been described. However, according to the signal transmitted from the controller 7, the current is output from the signal line driving unit 5. The time until output is not always the same as the time until the voltage of the power supply line changes. In the invention of the sixth embodiment, in order to synchronize the current output from the signal line driver 5 and the voltage input to the signal line driver 5, a delay circuit is provided between the controller 7 and each driver and controller. It is intended to be provided.

In FIG. 9, a first delay circuit 11 is provided between the controller 7 and the signal line driving unit 5, and a second delay circuit 12 is provided between the controller 7 and the scanning line driving unit 6. A third delay circuit 13 is provided between each unit 8 and the unit 8.
With this configuration, the current output from the signal line driver 5 and the voltage input to the signal line driver 5 are synchronized. Other configurations are the same as those of the first embodiment shown in FIG.

First, for control purposes, the signal to the drive current control unit 8, the signal to the signal line drive unit 5, and the signal to the scan line drive unit 6 need to be sent at the same timing. This is because, based on the video data input to the controller 7, the controller 7 selects a signal line, selects a scanning line, and sets a current value in accordance with the timing for displaying the image, and displays the video.
Here, when the voltage control unit 10 changes the voltage at the same time as setting the current value, the voltage change is not immediately reflected, so that the voltage change is delayed as shown in FIG. Loss or current shortage due to voltage shortage occurs. In order to prevent this, it is necessary to change the voltage in advance. This is because the delay circuit 11, 12, 13 delays signals to the drive current control unit 8, the signal line drive unit 5, and the scan line drive unit 6. This can be solved.

The premise that this configuration is required is that the voltage change takes time and the current change does not take time. Generally, the current change is performed in the drive IC which is the signal line drive unit 5. Therefore, dynamic current can be changed. On the other hand, the voltage controller 10 has a voltage changing function in the voltage controller, and inputs the changed voltage to the signal line driver 5. Usually, a plurality of signal line driving units 5 are connected to one voltage control unit 10 and the signal system is different from the current control. Therefore, the final voltage change takes longer time than the current change. There are many.
Therefore, the delay circuits 11, 12, and 13 are provided so that the current output from the signal line driver 5 and the voltage input to the signal line driver 5 coincide. Thereby, more efficient driving becomes possible.

In the above embodiment, the signal line driving unit 5 has been described with a current sink configuration in which current flows into the driving drive unit. However, instead of the current sink, the signal line driving unit 5 is configured with a current source that outputs current from the driving drive unit. May be.
Within the scope of the invention, the present invention can be freely combined with each other, or can be appropriately modified or omitted.

  As described above, according to the present invention, pixels are arranged in a matrix in the display unit, each display unit has a plurality of scanning lines and a plurality of signal lines, and one or a plurality of signal line driving units for driving the signal lines; A drive current control unit that changes a current output from the signal line drive unit, a voltage control unit that controls a voltage input to one or more signal line drive units, and a controller that performs the control In the display device, the current output from one or more signal line driving units is changed according to the video to be displayed, and the voltage input to the signal line driving unit is changed, thereby minimizing power loss and power consumption. Can be realized.

1: Display unit 2: Signal line
3: scanning line, 4: light emitting element,
5: signal line drive unit, 6: scan line drive unit,
7: Controller, 8: Drive current controller,
9: current-voltage conversion unit, 10: voltage control unit,
11, 12, 13: delay circuits.

Claims (8)

  In a display unit driving device having a plurality of scanning lines and a plurality of signal lines, and pixels of light emitting elements are arranged at intersections of the lines, a scanning line driving unit for driving the scanning lines, and driving the signal lines A signal line driving unit, a driving current control unit that changes a current output from the signal line driving unit according to an image displayed on the display unit, a voltage control unit that controls a voltage input to the signal line driving unit, A controller for controlling the scanning line driving unit, the signal line driving unit, the driving current control unit, and the voltage control unit, and a current output from the signal line driving unit according to a display image is controlled by the driving current control. When the voltage is changed by the unit, the voltage control unit changes the voltage input to the signal line driving unit. Display unit of the drive unit.   The voltage control unit reduces the voltage input to the signal line driving unit when the current output from the signal line driving unit is reduced, and drives the signal line when the current output from the signal line driving unit is increased. The display unit driving device according to claim 1, wherein the voltage input to the unit is also controlled to be large.   The display unit driving device according to claim 1, wherein the controller controls the current output from the signal line driving unit and the voltage input to the signal line driving unit individually for each of RGB colors.   The voltage control unit adjusts a voltage input to the signal line driving unit according to a position of the scanning line to be driven among a plurality of scanning lines in the display unit during a period of driving the scanning line. The display unit drive device according to claim 1.   When a plurality of display units are combined into a single screen, the voltage control unit determines a voltage to be input to the signal line driving unit for each display unit according to the video displayed on the display unit and the arrangement position of the display unit. The display unit driving device according to claim 1, wherein the display unit driving device is individually controlled.   A delay circuit is provided between the controller and the scan line driving unit and the signal line driving unit, and between the controller and the driving current control unit, and a current output from the signal line driving unit and the signal 6. The display unit driving apparatus according to claim 1, wherein the voltages input to the line driving unit are synchronized.   7. The display unit driving apparatus according to claim 1, wherein the signal line driving unit includes at least one current source. 8.   The display unit driving apparatus according to claim 1, wherein the signal line driving unit includes at least one current sink.

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