KR101849582B1 - Light emitting diode display - Google Patents

Abstract

The present invention relates to a light emitting diode display, and more particularly to a light emitting diode display capable of improving a picture quality by reducing a threshold voltage deviation between the driving switching elements, comprising: a plurality of pixels for displaying an image; Each pixel being controlled in accordance with a scan signal from a scan line and being connected between a data line and a first node; A merge switching element controlled in accordance with a light emission control signal from the light emission control line and connected between the first node and the second node; An initialization switching element controlled in accordance with a detection signal from the sense line, the initialization switch being connected between a reference line for transmitting a reference voltage and a third node; A sensing switching element connected between the third node and the second node, the sensing switching element being controlled according to a sensing signal from the sensing line; A driving switching element controlled in accordance with the voltage of the second node and connected between the fourth node and the fifth node; A light emission control switching element connected between a first driving line for transmitting a first driving voltage and the fourth node, the light emission control switching element being controlled according to a light emission control signal from the light emission control line; A light emitting diode connected between the fifth node and a second drive line for transmitting a second drive voltage; A first capacitor connected between the first node and the third node; And a second capacitor connected between the third node and the fourth node; Wherein the emission control signal, the sensing signal, and the scan signal are changed to an active state or an inactive state based on a sequentially generated initialization period, a threshold voltage detection period, a data writing period, and a light emission period; During the initialization period, the emission control signal and the sense signal are maintained in an active state, while the scan signal is maintained in an inactive state; The sensing signal remains active during the threshold voltage detection period, while the emission control signal and the scan signal remain inactive; The sensing signal and the scan signal remain active during the data writing period, while the emission control signal remains inactive; The light emission control signal remains active during the light emission period, while the sensing signal and the scan signal remain inactive; And a data signal corresponding to the pixel is supplied to the data line during the data writing period.

Description

[0001] LIGHT EMITTING DIODE DISPLAY [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode display device, and more particularly, to a light emitting diode display device capable of improving a picture quality by reducing a threshold voltage deviation between drive switching devices.

The pixels of the light emitting diode display include a drive switching element which is a constant current element. The current driving capability of the driving switching elements of these pixels is greatly affected by these threshold voltages. Accordingly, it is essential to accurately detect the threshold voltage between these driving switching elements to reduce the deviation of the threshold voltage between the driving switching elements, thereby improving the image quality of the LED display device.

However, in the prior art, since the threshold voltage of the driving switching device is influenced by the characteristics of the specific switching device, it is difficult to accurately detect the threshold voltage of the driving switching device. Therefore, conventionally, there has been a problem that a current deviation occurs between pixels and image quality is deteriorated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a light emitting diode display device capable of detecting a threshold voltage of a driving switching device in a source follower manner and obtaining a more accurate threshold voltage than a conventional one.

According to an aspect of the present invention, there is provided a light emitting diode display comprising: a plurality of pixels for displaying an image; Each pixel being controlled in accordance with a scan signal from a scan line and being connected between a data line and a first node; A merge switching element controlled in accordance with a light emission control signal from the light emission control line and connected between the first node and the second node; An initialization switching element controlled in accordance with a detection signal from the sense line, the initialization switch being connected between a reference line for transmitting a reference voltage and a third node; A sensing switching element connected between the third node and the second node, the sensing switching element being controlled according to a sensing signal from the sensing line; A driving switching element controlled in accordance with the voltage of the second node and connected between the fourth node and the fifth node; A light emission control switching element connected between a first driving line for transmitting a first driving voltage and the fourth node, the light emission control switching element being controlled according to a light emission control signal from the light emission control line; A light emitting diode connected between the fifth node and a second drive line for transmitting a second drive voltage; A first capacitor connected between the first node and the third node; And a second capacitor connected between the third node and the fourth node; Wherein the emission control signal, the sensing signal, and the scan signal are changed to an active state or an inactive state based on a sequentially generated initialization period, a threshold voltage detection period, a data writing period, and a light emission period; During the initialization period, the emission control signal and the sense signal are maintained in an active state, while the scan signal is maintained in an inactive state; The sensing signal remains active during the threshold voltage detection period, while the emission control signal and the scan signal remain inactive; The sensing signal and the scan signal remain active during the data writing period, while the emission control signal remains inactive; The light emission control signal remains active during the light emission period, while the sensing signal and the scan signal remain inactive; And a data signal corresponding to the pixel is supplied to the data line during the data writing period.

Further comprising a dummy period located between the data writing period and the light emitting period; During the dummy period, the sensing signal sequentially has an active state and an inactive state, and the emission control signal and the scan signal are maintained in an inactive state.

The data switching element, the merge switching element, the initial switching element, the sensing switching element, the driving switching element, and the emissive switching element are all p-type transistors.

The light emitting diode display device according to the present invention has the following effects.

First, in the present invention, since the threshold voltage of the driving switching element is detected by the source follower method, the threshold voltage can be detected more accurately than the method of detecting the threshold voltage of the driving switching element by the conventional diode connection method.

Second, in the present invention, since the sensing signal and the scan signal are supplied to the corresponding switching elements through independent lines, the length of the data writing period can be set longer than one horizontal time.

Thirdly, since the data signal is directly applied to the gate electrode of the driving switching element, the loss of the data signal can be reduced compared to the boosting method using the conventional capacitor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view illustrating a light emitting diode display device according to an embodiment of the present invention. FIG.
2 is a circuit diagram of a pixel according to an embodiment of the present invention.
FIG. 3 is a timing chart of the emission control signal, the sensing signal, the scan signal, and the data signal supplied to the pixel of FIG. 2, and the voltage of each node.
4A to 4E are diagrams for explaining the operation of a pixel according to an embodiment of the present invention.
5 is a view illustrating a simulation result for verifying the operation of the LED display device according to the embodiment of the present invention.
6A to 6C are diagrams for comparing a conventional light emitting diode display device and a light emitting diode display device according to an embodiment of the present invention.

1 is a view illustrating a light emitting diode display device according to an embodiment of the present invention.

1, a light emitting diode display device according to an embodiment of the present invention includes a display unit DSP, a system SYS, a control driver CD, a data driver DD, a timing controller TC, And a supply unit PS.

The display unit DSP includes a plurality of pixels PXL, a plurality of scan lines SL1 to SLi for transmitting a plurality of scan signals for sequentially driving the pixels PXL on a horizontal line basis, Lines DL1 to DLj, and power supply lines. On the other hand, although not shown, the display unit DSP further includes a plurality of sensing lines and emission control lines. Here, the number of scan lines, the number of sense lines, and the number of emission control lines may be the same.

These pixels PXL are arranged in a matrix on the display unit DSP. The pixels PXL are divided into a red pixel PXL for displaying red, a green pixel PXL for displaying green, and a blue pixel PXL for displaying blue.

The system SYS outputs a vertical synchronizing signal, a horizontal synchronizing signal, a clock signal, and image data through an interface circuit through a Low Voltage Differential Signaling (LVDS) transmitter of a graphic controller. The vertical / horizontal synchronizing signal and the clock signal output from the system SYS are supplied to the timing controller TC. In addition, the image data sequentially output from the system SYS is supplied to the timing controller TC.

The timing controller TC generates a data control signal, a scan control signal, a sensing control signal, and a light emission control signal by using a horizontal synchronizing signal, a vertical synchronizing signal, and a clock signal input to the timing controller TC, (CD).

The data driver DD samples the image data according to the data control signal from the timing controller TC and then outputs the sampling image corresponding to one horizontal line per horizontal period (1H, 2H, ...) Latches the data and supplies the latched image data to the data lines DL1 to DLj. That is, the data driver DD converts the video data from the timing controller TC into an analog pixel signal (data signal) by using the gamma voltage inputted from the power supply unit PS and supplies the converted video data to the data lines DL1 to DLj Supply.

The control driver CD outputs scan pulses, sense signals and emission control signals in accordance with a control signal from the timing controller TC. At this time, the control driver sequentially outputs i scan signals from the first scan signal to the i < th > scan signal every frame, and sequentially outputs i sense signals from the first sense signal to the i < th & And sequentially outputs i emission control signals from the first emission control signal to the i'th emission control signal every frame.

The power supply unit PS generates a gamma voltage, a first driving voltage Vdd, a second driving voltage Vss, and a reference voltage Vref necessary for driving the pixel PXL.

At this time, the first driving voltage VDD may be a constant voltage of about 10 [V] to 12 [V], the second driving voltage VSS may be a constant voltage of 0 [V] Vref) can be a constant voltage having a magnitude of 7 [V]. On the other hand, the data signal supplied to the data line may have a voltage of 0 [V] to 6 [V] depending on the gradation.

FIG. 2 is a circuit diagram of a pixel according to an embodiment of the present invention, and FIG. 2 is a diagram showing a circuit configuration provided in any one pixel in FIG.

One pixel PXL includes a data switching element Tr_DS, a merge switching element Tr_MG, an initialization switching element Tr_IT, a sensing switching element, a driving switching element, a light emission control switching element, A light emitting diode (OLED), a first capacitor C1, and a second capacitor C2.

The data switching element Tr_DS is controlled according to the scan signal SC from the scan line SCL and is connected between the data line DL and the first node N1.

The merge switching element Tr_MG is controlled in accordance with the emission control signal EM from the emission control line EML and is connected between the first node N1 and the second node N2.

The initialization switching element Tr_IT is controlled in accordance with the sense signal SS from the sense line SSL and is connected between the reference line VRL and the third node N3. A reference voltage Vref output from the power supply PS is applied to the reference line VRL.

The sensing switching element Tr_SS is controlled in accordance with the sensing signal SS from the sensing line SSL and is connected between the third node N3 and the second node N2.

The driving switching element Tr_DR is controlled according to the voltage of the second node N2 and is connected between the fourth node N4 and the fifth node N5.

The light emission control switching element Tr_EM is controlled in accordance with the light emission control signal EM from the light emission control line EML and is connected between the first drive line VDL and the fourth node N4. The first driving voltage Vdd output from the power supply PS is applied to the first driving line VDL.

The light emitting diode OLED is connected between the fifth node N5 and the second drive line VSL. That is, the anode electrode of the light emitting diode OLED is connected to the fifth node N5, and the cathode electrode is connected to the second driving line VSL. The second driving voltage Vss outputted from the power supply PS is applied to the second driving line VSL.

The first capacitor C1 is connected between the first node N1 and the third node N3.

The second capacitor C2 is connected between the third node N3 and the fourth node N4.

On the other hand, a light emitting capacitor Cel is connected between the fifth node N5 and the second drive line VSL. The light emitting capacitor Cel is an internal capacitor formed inside the light emitting diode OLED .

3 shows timing relationships between the emission control signals EM, EM, SC, and Vdata supplied to the pixel PXL of FIG. 2, and the voltages of the respective nodes Fig.

3, the emission control signal EM, the sense signal SS and the scan signal SC are sequentially generated in an initialization period Ti, a threshold voltage detection period Tth, a data write period Td ) And the light emission period (Te). Here, the active state of a signal means a state of a level at which the switching element can be turned on when the signal is supplied to the switching element. On the other hand, the inactive state of a signal means a state of a level at which the switching element can be turned off when a signal is supplied to the switching element. For example, when the switching elements are p-type as shown in FIG. 2, the active state of a signal supplied to the switching elements means a low-level voltage having a relatively low potential. On the other hand, the inactive state means a high level voltage having a relatively high potential.

The light emission control signal EM and the sense signal SS are maintained in the active state (low level voltage) during the initialization period Ti. On the other hand, during this period, the scan signal SC is held in the inactive state (high level voltage).

During the threshold voltage detection period Tth, the sense signal SS is maintained in the active state (low level voltage). On the other hand, during this period, the emission control signal EM and the scan signal SC are maintained in the inactive state (high level voltage).

The sense signal SS and the scan signal SC are maintained in the active state (low level voltage) during the data writing period Td. On the other hand, during this period, the emission control signal EM is maintained in the inactive state (high level voltage). Meanwhile, a data signal Vdata corresponding to the pixel PXL is supplied to the data line DL during the data writing period Td.

During the light emission period Te, the emission control signal EM is maintained in the active state (low level voltage). On the other hand, during this period, the sense signal SS and the scan signal SC are held in an inactive state (high level voltage).

Meanwhile, a dummy period Ty may be further included between the data writing period Td and the light emitting period Te described above. During this dummy period Ty, the sensing signal SS sequentially has an active state (low level voltage) and an inactive state (high level voltage). During this dummy period Ty, the emission control signal EM and the scan signal SC are maintained in the inactive state (high level voltage). At this time, the length of the period corresponding to the active state of the sense signal SS during the dummy period Ty is shorter than the length of the period corresponding to the inactive state.

In FIG. 3, V_N1 denotes the voltage of the first node N1, V_N2 denotes the voltage of the second node N2, and V_N4 denotes the voltage of the fourth node N4.

Hereinafter, the operation of the pixel PXL according to the embodiment of the present invention will be described in detail with reference to Figs. 2 and 3, and Figs. 4A to 4E.

4A to 4E are diagrams for explaining the operation of the pixel PXL according to the embodiment of the present invention. 4A to 4E, the switching element shown by the dotted line means the turned-off state, and the switching element surrounded by the circular dotted line means the turned-on state.

1) Initialization period ( Ti )

First, with reference to FIG. 3 and FIG. 4A, let us consider the operation of the pixel PXL in the initialization period Ti.

During the initialization period Ti, the emission control signal EM and the sense signal SS are maintained in the active state (low level voltage), as shown in Fig. On the other hand, during this period, the scan signal SC is held in the inactive state (high level voltage).

4A, the light emission control switching element Tr_EM and the merge switching element Tr_MG, which are supplied with the emission control signal EM in the active state, and the sensing signal SS The initialization switching element Tr_IT and the sense switching element Tr_SS are turned on. On the other hand, the data switching element Tr_DS supplied with the scan signal SC in an inactive state is turned off.

Then, the first driving voltage Vdd is supplied to the fourth node N4 through the turn-on emission control switching element Tr_EM. Also, the reference voltage Vref is supplied to the third node N3 through the turn-on initializing switching element Tr_IT. The reference voltage Vref is also supplied to the second node N2 through the turn-on sensing switching element Tr_SS. The reference voltage Vref is also supplied to the first node N1 through the turn-on merge switching element Tr_MG.

Thus, the fourth node N4 is initialized to the level of the first driving voltage Vdd, and the first node N1, the second node N2, and the third node N3 are both initialized to the level of the reference voltage Vref ). ≪ / RTI >

The difference between the reference voltage Vref applied to the second node N2 and the first driving voltage Vdd applied to the fourth node N4 is greater than the threshold voltage Vth of the driving switching element Tr_DR And the drive switching element Tr_DR is turned on. Then, the current flows to the fifth node N5 through the turn-on drive switching element Tr_DR. The voltage magnitude of the fifth node N5 is determined by this current.

At this time, when the voltage of the fifth node N5 rises and the difference voltage between the voltage of the fifth node N5 and the second driving voltage Vss exceeds the threshold voltage of the light emitting diode OLED, Ti may emit light from the light emitting diode OLED. However, since the initialization period Ti is extremely short, the light emitting diode OLED instantaneously emits light during this period, so that even if the light emitting diode OLED emits light during this initialization period Ti, it does not matter.

However, by setting the magnitude of the reference voltage Vref appropriately and reducing the rise of the voltage at the fifth node N5, the difference voltage between the voltage of the fifth node N5 and the second driving voltage Vss is reduced It is possible to prevent the light emitting diode (OLED) from emitting light in the initialization period (Ti) if the threshold voltage of the organic light emitting diode (OLED) is not exceeded.

2) Threshold voltage detection period ( Tth )

Next, the operation of the pixel PXL in the threshold voltage detection period Tth will be described with reference to FIGS. 3 and 4B.

During the threshold voltage detection period Tth, as shown in Fig. 3, the sense signal SS is maintained in the active state (low level voltage). On the other hand, during this period, the emission control signal EM and the scan signal SC are maintained in the inactive state (high level voltage).

According to such signals, the initializing switching element Tr_IT and the sensing switching element Tr_SS, which are supplied with the sensing signal SS in an active state, are turned on, as shown in FIG. 4B. On the other hand, the emission control switching element Tr_EM and the merge switching element Tr_MG supplied with the non-active emission control signal EM are turned off. In addition, the data switching element Tr_DS supplied with the scan signal SC in an inactive state is turned off.

Accordingly, the first node N1, the second node N2, and the third node N3 are all maintained at the level of the reference voltage Vref. On the other hand, during this period, the fourth node N4 is brought into a floating state because the light emission control switching element Tr_EM is turned off. At this time, the voltage of the fourth node N4 in the floating state is turned on Tr_DR). This will be described in detail as follows.

That is, since the differential voltage Vdd-Vref between the first driving voltage Vdd and the reference voltage Vref is set to be larger than the threshold voltage Vth of the driving switching element Tr_DR, the driving switching element Tr_DR is turned - Turns on. As the charge moves from the fourth node N4 in the floating state to the fifth node N5 through the turn-on drive switching element Tr_DR, the voltage of the fourth node N4 falls. The voltage of the fourth node N4 gradually falls and the voltage between the gate electrode and the source electrode of the driving switching element Tr_DR becomes lower than the threshold voltage Vth of the driving switching element Tr_DR. The drive switching element Tr_DR is turned off. At this time, the threshold voltage (Vth) of the driving switching element (Tr_DR) is stored in the second capacitor (C2). The voltage of the fourth node N4 at the time when the driving switching element Tr_DR is turned on is the difference voltage Vref-Vth between the reference voltage Vref and the threshold voltage Vth of the driving switching element Tr_DR, ≪ / RTI >

In this manner, the threshold voltage Vth of the driving switching element Tr_DR is detected in the source follower manner during the threshold voltage detection period Tth and is stored in the second capacitor C2.

Meanwhile, by setting the magnitude of the reference voltage Vref appropriately to reduce the rising width of the voltage at the fifth node N5 as described above, the difference voltage between the voltage of the fifth node N5 and the second driving voltage Vss The threshold voltage of the light emitting diode OLED can be prevented from exceeding the threshold voltage of the light emitting diode OLED to prevent the light emitting diode OLED from emitting light during the threshold voltage detection period Tth.

3) Data entry period ( Td )

Next, the operation of the pixel PXL in the data writing period Td will be described with reference to FIGS. 3 and 4C.

During the data writing period Td, the sense signal SS and the scan signal SC are maintained in the active state (low level voltage), as shown in Fig. On the other hand, during this period, the emission control signal EM is maintained in the inactive state (high level voltage). Meanwhile, a data signal Vdata corresponding to the pixel PXL is supplied to the data line DL during the data writing period Td.

According to such signals, as shown in FIG. 4C, the initialization switching element Tr_IT and the sense switching element Tr_SS, which are supplied with the sense signal SS in the active state, are turned on. On the other hand, the emission control switching element Tr_EM and the merge switching element Tr_MG supplied with the non-active emission control signal EM are turned off. In addition, the data switching element Tr_DS supplied with the scan signal SC in an inactive state is turned off.

Thus, both the second node N2 and the third node N3 are maintained at the level of the reference voltage Vref.

On the other hand, the data signal Vdata from the data line DL is supplied to the first node N1 through the turn-on data switching element Tr_DS. Accordingly, the voltage of the first node N1 falls to a level corresponding to the voltage of the data signal Vdata. The data signal Vdata applied to the first node N1 is held by the first capacitor C1.

On the other hand, during the data writing period Td, the driving switching element Tr_DR maintains the turned-off state.

4) The dummy period ( Ty )

Next, with reference to FIG. 3 and FIG. 4D, let us consider the operation of the pixel PXL in the dummy period Ty.

During the dummy period Ty, the sensing signal SS sequentially has an active state (low level voltage) and an inactive state (high level voltage), as shown in Fig. During this dummy period Ty, the emission control signal EM and the scan signal SC are maintained in the inactive state (high level voltage). At this time, the length of the period corresponding to the active state of the sense signal SS during the dummy period Ty is shorter than the length of the period corresponding to the inactive state.

According to these signals, the initializing switching element Tr_IT and the sensing switching element Tr_SS, which are finally supplied with the inactive sensing signal SS, are turned off as shown in FIG. 4D. Further, the light emission control switching element Tr_EM and the merge switching element Tr_MG, which are supplied with the light emission control signal EM in the inactive state, are turned off. In addition, the data switching element Tr_DS supplied with the scan signal SC in an inactive state is turned off.

Accordingly, the first node N1, the second node N2, the third node N3, the fourth node N4, and the fifth node N5 are both in a floating state. At this time, as the voltage of the fifth node N5 in the floating state changes toward the level of the threshold voltage of the light emitting diode OLED, the voltage between the source electrode and the drain electrode of the driving switching element Tr_DR ). That is, the voltage of the fourth node N4 also gradually drops. Also, as the voltage of the fourth node N4 falls, the voltages of the third node N3, the first node N1, and the second node N2 also drop at the same rate. If the dummy period Ty is sufficiently long, the voltage change of these nodes is performed until the voltage of the fifth node N5 is saturated with the threshold voltage of the light emitting diode OLED. At this time, the voltage difference between the fourth node N4, the second node N2, and the first node N1 remains the same, as can be seen from the dummy period Ty of FIG.

5) Light emitting period ( Te )

Next, with reference to FIG. 3 and FIG. 4E, let us consider the operation of the pixel PXL in the light emission period Te.

During the light emission period Te, the light emission control signal EM is maintained in the active state (low level voltage), as shown in Fig. On the other hand, during this period, the sense signal SS and the scan signal SC are held in an inactive state (high level voltage).

According to such signals, the emission control switching element Tr_EM and the merge switching element Tr_MG, which are supplied with the emission control signal EM in the active state, are turned on, as shown in FIG. 4E. On the other hand, the initializing switching element Tr_IT and the sensing switching element Tr_SS, which are supplied with the sensing signal SS in an inactive state, are turned off. In addition, the data switching element Tr_DS supplied with the scan signal SC in an inactive state is turned off.

Then, the first driving voltage Vdd is supplied to the fourth node N4 through the turn-on emission control switching element Tr_EM. Accordingly, the voltage of the fourth node N4 rises from the (Vref-Vdd) voltage to the first driving voltage Vdd. Then, the voltage of the third node N3 is bootstrapped by the first driving voltage Vdd and the second capacitor C2, and the voltage of the third node N3 and the voltage of the third node N3 The voltage of the first node N1 is bootstrapped. As a result, the first driving voltage Vdd applied to the fourth node N4, the voltage of the second capacitor C2, the voltage of the third node N3, and the voltage of the first node N1 by the first capacitor C1 The voltage rises to a level corresponding to (Vdata + Vdd- (Vref-Vth)). At this time, the second node N2 also has the same voltage as the first node N1 by the turn-on merge switching element Tr_MG. That is, the second node N2 also rises to a level corresponding to (Vdata + Vdd- (Vref-Vth)) by charge sharing between the first node N1 and the second node N2. Therefore, the driving switching element Tr_DR is turned on, and the turned-on driving switching element Tr_DR generates a driving current corresponding to the data signal Vdata and the threshold voltage Vth. As this driving current is supplied to the light emitting diode (OLED), the light emitting diode (OLED) starts to emit light.

As described above, according to the present invention, since the threshold voltage (Vth) of the driving switching device (Tr_DR) is detected by the source follower method, the threshold voltage (Vth) of the driving switching device (Tr_DR) The threshold voltage Vth can be detected. That is, conventionally, a switching element for connecting the gate electrode and the drain electrode of the driving switching element Tr_DR with each other in a diode manner is required, and the threshold voltage (Vth) of the driving switching element (Tr_DR) It is difficult to accurately detect the threshold voltage Vth of the driving switching element Tr_DR. However, in the present invention, since the threshold voltage (Vth) of the drive switching device (Tr_DR) is detected in the source follower manner without using such a switching device, a more accurate threshold voltage (Vth) can be obtained compared with the conventional case.

In the present invention, since the sense signal SS and the scan signal SC are supplied to the corresponding switching elements through independent lines, the length of the data write period Td can be set longer than one horizontal time. Therefore, it is advantageous to drive the LED display device at a high speed, and luminance uniformity between the pixels PXL in the OLED display area having a high resolution and a large-area panel can be improved.

In the present invention, since the data signal Vdata is directly applied to the gate electrode (second node N2) of the driving switching element Tr_DR, the loss of the data signal Vdata is reduced compared to the boosting method using the conventional capacitor Can be reduced.

FIG. 5 is a diagram illustrating a simulation result for verifying the operation of the LED display device according to the embodiment of the present invention. As shown in the figure, the initialization period Ti, the threshold voltage detection period Tth, The voltage of the fourth node N4 by the emission control signal EM, the sense signal SS and the scan signal SC during the data writing period Td, the dummy period Ty and the light emission period Te, The voltage of the node N2, and the pixel current of the pixel PXL are normally generated.

6A to 6C are views for comparing a conventional LED display device and a LED display device according to an embodiment of the present invention.

6A to 6C show a conventional light emitting diode display device, and B denotes a light emitting diode display device according to an embodiment of the present invention.

6A, when the threshold voltage of all the switching elements provided in the pixel PXL of the conventional light emitting diode display device is gradually changed from -1 [V] to 1 [V], the pixel PXL ) Are significantly larger than the average current deviation. However, as shown in FIG. 6A, when the threshold voltage of all the switching elements provided in the pixel PXL of the LED display apparatus according to the embodiment of the present invention changes from -1 [V] to 1 [V] It can be seen that the average current deviation between the pixels PXL is considerably small.

As shown in FIG. 6A, when the electron mobility characteristics of all the switching elements provided in the pixel PXL of the conventional light emitting diode display device are gradually changed from -10 [%] to 10 [%] It can be seen that the average current deviation between the PXLs is considerably large. However, as shown in FIG. 6B, the electron mobility characteristics of all the switching elements provided in the pixel PXL of the LED display device according to the embodiment of the present invention are changed from -10 [%] to 10 [%] The average current deviation between the pixels PXL is considerably small.

When the first driving voltage Vdd of the conventional LED display device is gradually changed from 0 [V] to -3 [V] as shown in Fig. 6A, the average current deviation between the pixels PXL is It is quite large. 6B, when the first driving voltage Vdd of the LED display device according to the embodiment of the present invention is changed from 0 [V] to -3 [V], the pixel PXL is turned on, And the average current deviation between the electrodes is considerably small.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. Will be clear to those who have knowledge of.

Tr_DS: Data switching element Tr_EM: Emission control switching element
Tr_MG: merge switching element Tr_IT: initial switching element
Tr_SS: sensing switching element Tr_DR: driving switching element
OLED: Light Emitting Diode N #: Primary Node
C #: n-th capacitor Cel: luminescence capacitor
SS: Detection signal SC: Scan signal
Vref: Reference voltage EM: Emission control signal
Vdd: first drive voltage Vdata; Data signal
Vss: second driving voltage SSL: sensing line
SCL: scan line EML: emission control line
VDL: first drive line VSL: second drive line
VRL: Reference line

Claims (3)

A plurality of pixels for displaying an image;
Each pixel has,
A data switching element controlled in accordance with a scan signal from the scan line and connected between the data line and the first node;
A merge switching element controlled in accordance with a light emission control signal from the light emission control line and connected between the first node and the second node;
An initialization switching element controlled in accordance with a detection signal from the sense line, the initialization switch being connected between a reference line for transmitting a reference voltage and a third node;
A sensing switching element connected between the third node and the second node, the sensing switching element being controlled according to a sensing signal from the sensing line;
A driving switching element controlled in accordance with the voltage of the second node and connected between the fourth node and the fifth node;
A light emission control switching element connected between a first driving line for transmitting a first driving voltage and the fourth node, the light emission control switching element being controlled according to a light emission control signal from the light emission control line;
A light emitting diode connected between the fifth node and a second drive line for transmitting a second drive voltage;
A first capacitor connected between the first node and the third node; And
And a second capacitor connected between the third node and the fourth node;
Wherein the emission control signal, the sensing signal, and the scan signal are changed to an active state or an inactive state based on a sequentially generated initialization period, a threshold voltage detection period, a data writing period, and a light emission period;
During the initialization period, the emission control signal and the sense signal are maintained in an active state, while the scan signal is maintained in an inactive state;
The sensing signal remains active during the threshold voltage detection period, while the emission control signal and the scan signal remain inactive;
The sensing signal and the scan signal remain active during the data writing period, while the emission control signal remains inactive;
The light emission control signal remains active during the light emission period, while the sensing signal and the scan signal remain inactive;
And a data signal corresponding to the pixel is supplied to the data line during the data writing period. The method according to claim 1,
Further comprising a dummy period located between the data writing period and the light emitting period;
Wherein during the dummy period, the sensing signal sequentially has an active state and an inactive state, and the emission control signal and the scan signal are kept inactive. The method according to claim 1,
Wherein the data switching element, the merge switching element, the initial switching element, the sensing switching element, the driving switching element, and the emissive switching element are both p-type transistors.

Images