KR102445341B1 - Display device and displaying method of the same, and programing method of the same - Google Patents

Abstract

According to the amount of deterioration of the light emitting element for each pixel, the light emission amount of the light emitting element is corrected in a more preferable manner. A display device including pixel circuits arranged in a matrix, the pixel circuit comprising: a light emitting element emitting light at a luminance according to an amount of current; a driving circuit for controlling the amount of current supplied to the light emitting element according to the applied first voltage; a first transistor for switching between a conductive state and a non-conductive state between the light emitting element and the driving circuit according to a first gate voltage applied to a control terminal; an optical sensor detecting the luminance of light emitted from the light emitting device; a capacity for maintaining an applied second voltage in accordance with the first voltage; and a second transistor that controls application of the first gate voltage to the first transistor. wherein the second transistor is switched to a conductive state based on a detection result of the optical sensor and a second gate voltage determined according to the second voltage held in the capacitor, and the first transistor is Provided is a display device characterized in that the two transistors are switched to a conductive state and thus controlled to a non-conductive state based on the applied first gate voltage.

Description

Display device and display method {DISPLAY DEVICE AND DISPLAYING METHOD OF THE SAME, AND PROGRAMING METHOD OF THE SAME}

The present invention relates to a display device, a display method, and a program.

In recent years, as a display device, a flat panel (flat panel type) display device in which pixels including self-luminous elements such as organic EL (Organic Electro-Luminescence) elements are arranged in a matrix shape (matrix shape) has been provided. .

Japanese Patent Laid-Open No. 2001-524090 Japanese Patent Laid-Open No. 2006-506307

On the other hand, it is known that a self-luminous element such as an organic EL element (hereinafter, simply referred to as a "light-emitting element") has a property of deterioration in proportion to the light-emitting luminance and the light-emitting time. Since the content of the image displayed on the display device is not uniform, the deterioration of the light emitting element (organic EL element) is not uniform. For example, a light emitting device displaying a color with high luminance such as white may be more easily degraded than a light emitting device displaying a color with low luminance such as black.

The luminance of the light emitting device in which deterioration has progressed relatively tends to decrease compared to other light emitting elements in which deterioration is slow. Such a phenomenon is generally known as "image sticking (burn-in)".

As described above, an example of a technique for reducing a change in luminance between pixels due to deterioration of a light emitting element is disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2001-524090). That is, according to the technique disclosed in Patent Document 1, a part of the light from the light emitting element is received by a photodiode provided in the pixel circuit, and the amount of current supplied to the light emitting element is controlled based on the light reception result, so that the luminance of the light emitting element is deteriorated. is compensating for However, in the technique according to Patent Document 1, since the transistor for controlling the amount of current supplied to the light emitting element is operated in the saturation region, it is affected by variations in the characteristics of the transistor and the operation may become unstable.

In addition, as another example, in Patent Document 2 (Japanese Patent Laid-Open Publication No. 2006-506307), part of the light from the light emitting element is received by a photodiode provided in the pixel circuit, and based on the light reception result, the light emission time of the light emitting element ( A technique for compensating for luminance deterioration of the light emitting element by controlling the duty ratio) is disclosed. However, according to Patent Document 2, due to the driving method of controlling the amount of light emitted by the light emitting element by controlling the duty ratio at the time of light emission, when a moving picture is displayed, a so-called pseudo outline in which an outline not originally displayed is observed occurs. There are cases.

Here, the present invention has been made in view of the above problems, and an object of the present invention is a display device, a display capable of correcting the light emission amount of the light emitting element in a more preferable form according to the amount of deterioration of the light emitting element for each pixel. To provide a method, and a program.

A pixel circuit of a display device according to an embodiment of the present invention includes a light emitting device, a driving circuit, a first transistor, a first optical sensor, a capacitor, and a second transistor. The light emitting device emits light having a luminance according to the amount of current, and the driving circuit controls the amount of current supplied to the light emitting device in response to the first applied voltage. The first transistor switches an electrical connection between the light emitting device and the driving circuit in response to a first gate voltage applied to the first control terminal. The first optical sensor detects the luminance of the light emitted from the light emitting device. The capacitor maintains a second voltage reflecting the first voltage. The second transistor provides the first gate voltage to the first transistor. The second transistor is turned on in response to a second gate voltage determined by the detected light luminance and the second voltage maintained at the capacitance. The first transistor is turned off in response to the first gate voltage applied when the second transistor is turned on.

The discharge period of the second voltage held in the capacitor is controlled according to the luminance of the detected light. A light emission period of the light emitting device may be controlled based on the discharge period.

The first transistor may include the first control terminal, a first terminal, and a second terminal.

The second transistor may include a second control terminal, a third terminal, and a fourth terminal.

The third terminal of the second transistor may be connected to the first control terminal of the first transistor. One terminal of the first optical sensor and one terminal of the capacitor may each be connected to the second control terminal of the second transistor.

and a second optical sensor connected in series to the first optical sensor and connected in parallel with respect to the capacitance and to which the light emitted from the light emitting element is not directly applied, wherein the discharge period of the second voltage is the first optical sensor and a detection result of the second optical sensor.

A first switching element for switching an electrical connection between the second control terminal and the third terminal may be further included.

The second transistor and the first switching element may be turned on during a preparation period defined before the light emission period of the light emitting element, and the second control terminal may have a potential reflecting a threshold voltage of the second transistor. .

The threshold voltage may be compensated for the second voltage.

During the preparation period, the potential of the second control terminal of the second transistor may be changed from a value to which the threshold voltage is not reflected to a value to which the threshold voltage is reflected.

The pixel circuit of the display device according to an embodiment of the present invention may further include a second capacitor and a second switching element providing the second voltage to one terminal of the first capacitor.

The second capacitor is interposed between the second switching element and one terminal of the first capacitor. When the second switching element is turned on, the second voltage is applied to the one terminal of the first capacitor through the second capacitor.

After the second control terminal of the second transistor has a potential reflecting the threshold voltage of the second transistor, the second switching element may be turned on.

A third switching element providing the second voltage to the fourth terminal of the second transistor may be further included.

When the second transistor, the first switching element, and the third switching element are turned on, the second voltage is applied to the second control terminal of the second transistor, so that the second control terminal is connected to the second control terminal. 2 The threshold voltage of the transistor may have a reflected potential.

The third switching element may be switched in synchronization with the first switching element.

In the image display method according to an embodiment of the present invention, the second transistor is turned on based on a second gate voltage determined by the luminance of the light detected by the first optical sensor and the second voltage maintained in the capacitance. It may include turning on the first transistor and turning off the first transistor based on the first gate voltage applied when the second transistor is turned on.

As described above, according to the present invention, there is provided a display device, a display method, and a program capable of correcting the amount of light emitted by the light emitting element in a more preferable manner according to the amount of deterioration of the light emitting element for each pixel circuit.

1 is an explanatory diagram for explaining a principle of luminance deterioration compensation in a display device according to an embodiment of the present invention.
2 is an explanatory diagram for explaining the principle of luminance deterioration compensation in the display device according to the embodiment of the present invention.
3 is an explanatory diagram for explaining an example of the configuration of the display device according to the first embodiment of the present invention.
4 is an explanatory diagram for explaining an example of the configuration of the pixel circuit according to the embodiment.
5 is a schematic timing chart for explaining an example of driving timing of the pixel circuit 110 according to the embodiment.
FIG. 6 is an explanatory diagram for explaining a connection relationship between elements constituting a pixel circuit at each timing shown in FIG. 5 .
FIG. 7 is an explanatory diagram for explaining a connection relationship between elements constituting a pixel circuit at each timing shown in FIG. 5 .
FIG. 8 is an explanatory diagram for explaining a connection relationship between elements constituting a pixel circuit at each timing shown in FIG. 5 .
9 is an explanatory diagram for explaining a connection relationship between elements constituting a pixel circuit at each timing shown in FIG. 5 .
FIG. 10 is an explanatory diagram for explaining a connection relationship between elements constituting a pixel circuit at each timing shown in FIG. 5 .
11 is an explanatory diagram for explaining an example of control of a data signal for compensation according to emission luminance.
12 is an explanatory diagram for explaining an example of control of a data signal for compensation according to emission luminance.
13 is an explanatory diagram for explaining an example of control of a data signal for compensation according to emission luminance.
14 is an explanatory diagram for explaining an example of the configuration of the pixel circuit according to the first embodiment of the present invention.
15 is a schematic timing chart for explaining an example of driving timing of the pixel circuit according to the embodiment.
FIG. 16 is an explanatory diagram for explaining a connection relationship between elements constituting a pixel circuit at each timing shown in FIG. 15 .
17 is an explanatory diagram for explaining a connection relationship between elements constituting a pixel circuit at each timing shown in FIG. 15 .
FIG. 18 is an explanatory diagram for explaining a connection relationship between elements constituting a pixel circuit at each timing shown in FIG. 15 .
19 is an explanatory diagram for explaining a connection relationship between elements constituting a pixel circuit at each timing shown in FIG. 15 .
FIG. 20 is an explanatory diagram for explaining a connection relationship between elements constituting a pixel circuit at each timing shown in FIG. 15 .

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of this invention is described in detail, referring an accompanying drawing. In addition, in this specification and drawing, about the component which has substantially the same functional structure, the same code|symbol is attached|subjected, and redundant description is abbreviate|omitted.

<1. Principle of Compensation>

First, in order to more easily understand the characteristics of the display device according to the embodiment of the present invention, the display device controls (ie, corrects) the amount of light emitted by the display device according to the amount of deterioration of the light emitting device for each pixel circuit. , luminance deterioration compensation) will be described.

For example, FIGS. 1 and 2 are explanatory diagrams for explaining the principle of luminance deterioration compensation in the display device according to the embodiment of the present invention. For example, FIG. 1 shows a circuit configuration of a pixel circuit of a display device according to an embodiment of the present invention. In particular, it was modeled with a focus on the circuit for luminance degradation compensation. In addition, FIG. 2 shows the schematic driving timing of the circuit shown in FIG. 1 with a particular focus on the light emission time of the light emitting element.

The pixel circuit shown in FIG. 1 includes a driving circuit 117 , a control transistor EM-TFT, an organic EL element OLED, an optical sensor Ps, and a sensor capacitor Cs.

The organic EL element OLED is a so-called current driving element, and the luminance of light emission changes in proportion to the supplied driving current Ic.

The driving circuit 117 receives the data signal (Data, a voltage signal according to the luminance) and causes the organic EL element OLED to emit light with a luminance according to the data signal (Data). The driving circuit 117 outputs a driving current Ic corresponding to the data signal Data.

The driving circuit 117 may be constituted by, for example, a so-called 2T1C circuit including two transistors and one storage capacitor, a so-called 6T1C circuit including six transistors and one storage capacitor, or the like. In such a configuration, the driving circuit 117 includes, for example, a so-called driving transistor, and by supplying the data signal Data to the gate terminal of the driving transistor, the driving circuit 117 changes according to the data signal Data. The source-drain current is output as the driving current Ic.

Of course, the configuration of the driving circuit 117 shown above is only an example, and if the output driving current Ic can be controlled according to the supplied data signal Data (that is, the data signal Data is converted into an analog current (Ic)), the configuration of the driving circuit 117 is not particularly limited.

The control transistor EM-TFT may be configured by, for example, a P-channel type metal-oxide-semiconductor field-effect transistor (MOSFET).

The driving circuit 117 is connected to the source terminal side of the control transistor EM-TFT, and the anode side of the organic EL element OLED is connected to the drain terminal side. Further, a power supply voltage ELVSS is connected to the cathode side of the organic EL element. That is, when the control transistor EM-TFT is turned on (that is, a current path is formed between the source and drain), the driving current Ic from the driving circuit 117 is applied to the control transistor EM-TFT. is supplied to the organic EL element OLED through the , and the organic EL element OLED emits light corresponding to the driving current Ic.

The optical sensor Ps may be configured by, for example, a photodiode or a phototransistor. Moreover, as a material of the optical sensor Ps, polysilicon, amorphous silicon, etc. are mentioned, for example. In the optical sensor Ps, one terminal is connected to the gate terminal of the control transistor EM-TFT, and the other terminal is connected to an electrode having a predetermined potential. The optical sensor Ps receives a part of the light emitted from the organic EL element OLED.

In addition, one terminal of the sensor capacitor Cs is connected to the gate terminal of the control transistor EM-TFT, and the other terminal is connected to an electrode of a predetermined potential similarly to the optical sensor Ps. The sensor capacitance Cs maintains the voltage applied to the gate terminal of the control transistor EM-TFT.

When the light emitted from the organic EL element OLED is detected by the optical sensor Ps, a current corresponding to the luminance of the detected light (that is, the luminance of the organic EL element OLED) flows through the optical sensor Ps. Hereinafter, the current flowing through the optical sensor Ps corresponding to the detection result (the luminance of the detected light) of the optical sensor Ps is sometimes described as "sensing current Is".

The voltage maintained in the sensor capacitance Cs is discharged by the sensing current Is according to the detection result of the optical sensor Ps, and the gate terminal of the control transistor EM-TFT is discharged by the discharge of the sensor capacitance Cs. potential rises. That is, the potential Vg of the gate terminal of the control transistor EM-TFT rises depending on the sensing current Is according to the luminance of the light detected by the optical sensor Ps, and the time constant of the sensor capacitance Cs. . And, when the potential Vg of the gate terminal of the control transistor EM-TFT reaches the threshold voltage Vth of the control transistor EM-TFT, the control transistor EM-TFT is turned off (that is, The current path between the source and drain is blocked).

Hereinafter, a state in which a current path is formed in a transistor or a switching element is referred to as a “turn-on state”, and a state in which the current path is blocked is sometimes referred to as a “turn-off state”.

Here, with reference to FIG. 2 , compensation (correction) of the emission amount of the organic EL element OLED according to the amount of deterioration of the organic EL element OLED will be described. In FIG. 2 , reference numeral T ₀ denotes a light emission period of the organic EL element OLED defined in one frame period. In addition, reference sign T ₁ has shown the light emission period of the organic EL element OLED before deterioration. In addition, the state before deterioration of organic electroluminescent element OLED may be described later as "initial state".

If the organic EL element OLED is deteriorated compared to the initial state, the luminance of the organic EL element OLED decreases according to the deterioration, so that the sensing current Is according to the optical sensor Ps is ) decreases with deterioration. Since the discharge time of the voltage held in the sensor capacitance Cs becomes longer and the time for the potential Vg of the gate terminal of the control transistor EM-TFT to reach the threshold voltage Vth becomes longer, the organic EL element The light emission period of (OLED) is also lengthened. In FIG. 2 , the compensated light emission period indicated by the reference symbol T ₂ represents the light emission period extended according to the deterioration of the organic EL element OLED.

Here, the amount of light emitted from the organic EL element OLED is proportional to the current flowing through the organic EL element OLED (ie, the driving current Ic) and the length of the light emission period. Therefore, in the display device according to the embodiment of the present invention, the luminance deterioration of the organic EL element OLED can be compensated for by extending the light emission period according to the deterioration of the organic EL element OLED.

In addition, an example of the detailed configuration of the pixel circuit for extending the light emission period according to the deterioration of the organic EL element OLED described above will be separately described later.

The principle of control in which the display device according to the embodiment of the present invention compensates (corrects) the light emission amount of the light emitting element according to the deterioration amount of the light emitting element for each pixel circuit has been described above with reference to FIGS. 1 and 2 .

<2. First embodiment>

[2.1. Configuration of display device]

Next, the display device according to the first embodiment of the present invention will be described. First, an example of a functional configuration of the display device 10 according to the present embodiment will be described with reference to FIG. 3 . 3 is an explanatory diagram for explaining an example of the configuration of the display device 10 according to the present embodiment. In addition, in FIG. 3, the horizontal direction of a figure is shown as a row direction (X direction), and a vertical direction is shown as a column direction (Y direction). As shown in FIG. 3 , the display device 10 according to the present embodiment includes a display unit 100 , a scan driver 120 , and a data driver 130 .

The display unit 100 includes a plurality of pixel circuits 110 . An image corresponding to the data signal is displayed in the display pixel defined by the plurality of pixel circuits 110 . A plurality of scan lines 112 and 113 and a plurality of initialization signal lines 116 each extending in the row direction (X direction) are disposed on the display unit 100 . In addition, a plurality of data lines 114 and compensation signal lines 115 each extending in a column direction (Y direction) are disposed on the display unit 100 . In addition, in this description, as shown in FIG. 3 , in the display unit 100 , n (n is an integer of 2 or more) scanning lines 112, n (n is an integer of 2 or more) scanning lines 113, and n (n is an integer greater than or equal to 2) initialization signal lines 116, m (m is an integer greater than or equal to 2) data lines 114, and m (m is an integer greater than or equal to 2) compensation signal lines 115 are arranged can be

Each of the plurality of pixel circuits 110 is disposed in a region where the plurality of scan lines 112 and 113 extending in the row direction (X direction) and the plurality of data lines 114 extending in the column direction (Y direction) intersect each other. Each can be arranged. A detailed configuration of the pixel circuit 110 will be separately described later.

In addition, a high potential power supply (VDD, see FIG. 4 ), a low potential power supply (VGL, see FIG. 4 ), and power supply voltages (ELVDD and ELVSS, see FIG. 4 ) are connected to the display unit 100 , Based on the control by the control circuit, a voltage corresponding to the power source is applied from each power source.

A plurality of scan lines 112 and 113 arranged in the Y direction and a plurality of initialization signal lines 116 are connected to the scan driver 120 .

The scan driver 120 supplies scan signals to pixel rows through a plurality of scan lines 112 and 113 arranged in the X direction. At this time, the scan signal is supplied to the scan line 113 at a timing that is earlier than the timing at which the scan signal is supplied to the scan line 112 by one horizontal scanning period. That is, if the Scan signal supplied in the i-th (1 ≤ i ≤ n) horizontal scanning period is referred to as a Scan(i) signal, the pixel circuit 110 receives the Scan(i) signal through the scan line 112 and A Scan(i-1) signal is received through the scan line 113 .

Also, the scan driver 120 supplies the initialization signal Init to the pixel circuit 110 according to the timing of supplying the scan signal to the pixel circuit 110 . In addition, in the following description, the initialization signal Init supplied corresponding to the i-th horizontal scanning period may be described as "initialization signal Init(i)".

A plurality of data lines 114 and a plurality of compensation signal lines 115 arranged in the X direction are connected to the data driver 130 .

The data driver 130 supplies data signals Data (voltage signals) according to emission luminance (in other words, grayscale) corresponding to the pixel columns through the data lines 114 arranged for each pixel column. Note that, in the following description, the data signal Data supplied to the pixel circuit 110 in the j-th column may be described as "data signal Data(j)".

In addition, the data driver 130 supplies the compensation data signals Comp. Data according to the emission luminance (grayscale) corresponding to the pixel columns through the compensation signal lines 115 arranged for each pixel column. Note that, in the following description, the compensation data signal Comp. Data supplied to the pixel circuit 110 in the j-th column may be referred to as “Data(j)”.

An example of the functional configuration of the display device 10 according to the present embodiment has been described above with reference to FIG. 3 . In addition, the functional configuration of the display device 10 described above is merely an example, and if it is possible to supply each signal to the pixel circuit 110 , the configuration of the scan driver 120 or the data driver 130 . is not particularly limited.

[2.2. Configuration of pixel circuit]

Next, an example of the pixel circuit 110 according to the present embodiment will be described with reference to FIG. 4 . 4 is an explanatory diagram for explaining an example of the pixel circuit 110 according to the present embodiment. FIG. 4 illustrates an example of a pixel circuit 110 disposed in an nth row among a plurality of pixel circuits 110 constituting the display unit 100 shown in FIG. 3 . In addition, since it is possible to have the same structure as that of the pixel circuit 110 shown in FIG. 4 with respect to the other pixel circuit 110 which comprises the display part 100, detailed description is abbreviate|omitted.

As shown in FIG. 4 , the pixel circuit 110 includes an organic EL element OLED, a driving circuit 117 , control transistors M1 and M3 , switching transistors M2 , M4 , M15 , and M31 , and optical sensors. (Ps1 and Ps2), a sensor capacitance (Cs), and capacitances (C1 and C2).

The control transistors M1 and M3 may be configured by, for example, a P-channel type metal-oxide-semiconductor field-effect transistor (MOSFET).

In addition, the driving circuit 117 corresponds to the driving circuit 117 described above with reference to FIG. 1 .

As shown in FIG. 4 , the driving circuit 117 is connected to the source terminal side of the control transistor M1 , and the anode side of the organic EL element OLED is connected to the drain terminal side. Further, a power supply voltage ELVSS is connected to the cathode side of the organic EL element.

The driving circuit 117 is connected to the data line 114 via a switching transistor M31. The switching transistor M31 is turned on or off in response to a Scan(n) signal transmitted through the scan line 112 . That is, as the switching transistor M31 is turned on based on the Scan(n) signal, the data signal Data transmitted through the data line 114 is supplied to the driving circuit 117 . In addition, a power supply voltage is supplied to the driving circuit 117 from a power supply voltage ELVDD (not shown).

With this configuration, the driving circuit 117 supplies the driving current Ic according to the data signal Data supplied through the data line 114 and the switching transistor M31 to the source terminal of the control transistor M1. do.

The high potential power supply VDD is connected to the source terminal of the control transistor M3, and the gate terminal of the control transistor M1 is connected to the drain terminal. That is, as the control transistor M3 is turned on or off, the control transistor M1 is turned on or off. Note that the node to which the gate terminal of the control transistor M1 is connected is hereinafter referred to as "node Na" in some cases. In addition, a detailed description of the timing at which each of the control transistors M1 and M3 is switched to the turn-on state or the turn-off state will be separately described later according to the driving timing of the pixel circuit 110 .

The capacitor C1 is connected to a node Nb having one terminal connected to the gate terminal of the control transistor M1, and the other terminal connected to the high potential power supply VDD. In addition, a switching transistor M2 is interposed between the node Nb and the low potential power supply VGL. The switching transistor M2 is turned on or off according to the initialization signal Init supplied through the initialization signal line 116 .

In addition, when the node to which the gate terminal of the control transistor M3 is connected is referred to as "node Na", the compensation signal line 115 and the node Na are connected through the switching transistor M15 and the capacitor C2. do. The switching transistor M15 is turned on or off according to a Scan(n) signal transmitted through the scan line 112 . That is, as the switching transistor M15 is turned on based on the Scan(n) signal, the compensation data signal Comp.Data transmitted through the compensation signal line 115 is supplied to the node Na.

A switching transistor M4 is interposed between the drain terminal (in other words, the node Nb) and the gate terminal (in other words, the node Na) of the control transistor M3. The switching transistor M4 diode-connects the control transistor M3 by bypassing between the gate terminal and the drain terminal of the control transistor M3. The switching transistor M4 compensates for a change in the threshold voltage of the control transistor M3. The switching transistor M4 is turned on or off in response to a Scan(n-1) signal transmitted through the scan line 113 .

The optical sensors Ps1 and Ps2 may be configured by, for example, a photodiode or a phototransistor. Moreover, as a material of the optical sensors Ps1 and Ps2, polysilicon, amorphous silicon, etc. are mentioned, for example.

The optical sensor Ps1 (hereinafter, referred to as the first optical sensor) receives a portion of the light emitted from the organic EL element OLED. The first optical sensor Ps1 has one terminal connected to the node Na connected to the gate terminal of the control transistor M3, and the other terminal connected to the low potential power supply VGL.

The optical sensor Ps2 (hereinafter, referred to as the second optical sensor) does not directly receive the light emitted from the organic EL device OLED. A noise component such as reflected light entering from the surroundings or light provided from another pixel circuit 110 is detected depending on factors such as the structure of the pixel circuit 110 . The second optical sensor Ps2 has one terminal connected to the node Na connected to the gate terminal of the control transistor M3, and the other terminal connected to the high potential power supply VDD. At this time, the optical sensors Ps1 and Ps2 are connected in series. With such a configuration, based on the detection result of the first optical sensor Ps1, from the sensing current Is flowing through the first optical sensor Ps1, the noise component based on the detection result of the second optical sensor Ps2 It is removed (cancelled).

As for the sensor capacitance Cs, one terminal is connected to the node Na to which the gate terminal of the control transistor M3 is connected, and the other terminal is connected to the low potential power supply VGL. The compensation data signal Comp.Data held in the sensor capacitance Cs is discharged according to the detection results of the optical sensors Ps1 and Ps2, and the gate voltage Vg of the control transistor M3 is discharged by the discharge. Controlled. In addition, the detail is mentioned later separately.

An example of the configuration of the pixel circuit 110 according to the present embodiment has been described above with reference to FIG. 4 .

[2.3. drive timing]

Next, an example of driving timing of each element constituting the pixel circuit 110 according to the present embodiment shown in FIG. 4 will be described with reference to FIGS. 5 to 10 . 5 is a schematic timing chart for explaining an example of driving timing of the pixel circuit 110 according to the present embodiment. 6 to 10 are explanatory diagrams for explaining the connection relationship between elements constituting the pixel circuit 110 at each timing shown in FIG. 5 .

5 , the display device 10 according to the present embodiment divides one frame period (Frame) into a plurality of periods ( T ₁₁ to T ₁₆ ) to drive the pixel circuit 110 . In addition, among the plurality of periods T ₁₁ to T ₁₆ , some periods T ₁₃ to T ₁₅ correspond to the light emission periods in which the organic EL element OLED emits light, and other periods T ₁₁ , T ₁₂ , and T ₁₆ ) corresponds to the non-light-emission period in which the organic EL element OLED is turned off. In addition, FIG. 5 shows changes in the initialization signal Init, the Scan(n-1) signal, and the Scan(n) signal appearing in a plurality of periods T ₁₁ to T ₁₆ and potentials of the nodes Na and Nb. Changes are shown. In addition, the period indicated by the partial periods T ₁₁ and T ₁₂ corresponds to one horizontal scanning period 1H. Further, a period indicated by the periods T ₁₃ and T ₁₄ having the same time width as the periods indicated by the periods T ₁₁ and T ₁₂ also corresponds to one horizontal scanning period 1H.

First, the first period T ₁₁ will be described. 6 illustrates a connection relationship between elements constituting the pixel circuit 110 in the first period T ₁₁ . During the first period T ₁₁ , the switching transistor M2 is switched to the turn-on state according to the initialization signal Init, and the switching transistor M4 is switched to the turn-on state according to the Scan(n-1) signal do. Also, at this time, the switching transistors M15 and M31 are in a turned-off state. Also, the control transistors M1 and M3 are turned off.

As shown in FIG. 6 , when the switching transistors M2 and M4 are switched to the turned-on state, the low-potential power supply VGL is written to the gate terminal of the control transistor M3. Thereby, the gate terminal (in other words, the potential of the node Na) of the control transistor M3 is initialized to the low potential power supply VGL.

Next, the second period T ₁₂ will be described. 7 illustrates a connection relationship between elements constituting the pixel circuit 110 in the second period T ₁₂ . During the second period T ₁₂ , the switching transistor M2 is switched to a turn-off state according to the initialization signal Init. Also, during the first period T ₁₁ , the gate terminal of the control transistor M3 is initialized by the voltage VGL, so that the control transistor M3 is switched to the tone-on state during the second period T ₁₂ . Therefore, each of the control transistor M3 and the switching transistor M4 is turned on, and the drain terminal (node Nb) and gate terminal (node Na) of the control transistor M3 are bypassed. The control transistor M3 is so-called diode-connected.

Here, if the threshold voltage of the control transistor M3 is Vth, the potential of the gate terminal (node Na) of the control transistor M3 is diode-connected so that the potential of the control transistor M3 reflects the threshold voltage Vth. It is controlled by the potential (VDD-Vth). By such control, a change in the threshold voltage Vth of the control transistor M3 between the plurality of pixel circuits 110 is compensated for.

Next, the third period T ₁₃ and the fourth period T ₁₄ will be described. FIG. 8 shows the connection relationship between elements constituting the pixel circuit 110 in the third period T ₁₃ and the fourth period T ₁₄ . During the third period T ₁₃ and the fourth period T ₁₄ , the switching transistor M31 is switched to the turn-on state in response to the Scan(n) signal. Accordingly, the data signal Data transmitted through the data line 114 is supplied to the driving circuit 117 .

In addition, the switching transistor M15 is switched to a turn-on state in response to the Scan(n) signal during the third period T ₁₃ and the fourth period T ₁₄ , and in response to the Scan(n-1) signal The switching transistor M4 is switched to a turn-off state. Thereby, the compensating data signal Comp.Data transmitted through the compensating signal line 115 is transmitted through the switching transistor M15 and the capacitor C2 to the gate terminal (node Na) of the control transistor M3. ) is lit. Also, at this time, since the gate voltage Vg of the control transistor M3 becomes higher than the threshold voltage Vth of the control transistor M3, the control transistor M3 is switched to a turn-off state.

In addition, the switching transistor M2 is switched to the turn-on state during the third period T ₁₃ by the initialization signal Init and is switched to the turn-off state during the fourth period T ₁₄ . Thereby, the low potential power supply VGL is written to the gate terminal (node Nb) of the control transistor M1, and the control transistor M1 is switched to the turn-on state.

Based on the above control, the driving current Ic corresponding to the data signal Data is supplied from the driving circuit 117 to the organic EL element OLED through the control transistor M1, and the organic EL element ( OLED) emits light with a luminance corresponding to the driving current Ic.

Next, the fifth period T ₁₅ will be described. 9 illustrates a connection relationship between elements constituting the pixel circuit 110 in the fifth period T ₁₅ . During the fifth period T ₁₅ , the switching transistors M15 and M31 are switched to the turn-off state in response to the Scan(n) signal.

When the switching transistor M15 is switched to the turn-off state, the gate terminal (node Na) of the control transistor M3 floats, and the compensation data signal Comp.Data is maintained in the sensor capacitance Cs. . In addition, as the organic EL element OLED emits light, a sensing current Is corresponding to the luminance of the emitted light flows through the optical sensors Ps1 and Ps2. At this time, the compensation data signal Comp.Data held in the sensor capacitance Cs is discharged by the sensing current Is, and the gate voltage Vg of the control transistor M3 is lowered by the discharge.

Next, the sixth period T ₁₆ will be described. 10 illustrates a connection relationship between elements constituting the pixel circuit 110 in the sixth period T ₁₆ . As shown in FIG. 10 , the gate voltage Vg of the control transistor M3 is adjusted to the threshold value of the control transistor M3 by the sensing current Is based on the luminance of the detected light of the optical sensors Ps1 and Ps2. It is lowered to reach the voltage Vth, and the control transistor M3 is switched to the turn-on state. Thereby, the voltage VDD is written to the gate terminal (node Nb) of the control transistor M1, and the control transistor M1 is switched to the turn-off state. As a result, the driving current Ic supplied from the driving circuit 117 to the organic EL element OLED is cut off, and the organic EL element OLED is turned off.

In addition, the above-described series of operations can be achieved by a program for causing the CPU of the device to operate each component of the display device 10 to function. This program can be configured to run through an operating system (OS) installed in the device. In addition, this program is not limited to the location in which it is stored, as long as it is readable by the apparatus which includes the structure which performs the above-mentioned process. For example, the program may be stored in a recording medium that is connected from the outside of the apparatus. In this case, what is necessary is just to connect the recording medium in which the program is stored to an apparatus so that the CPU of the apparatus may be comprised so that a program may be executed.

An example of driving timing of each element constituting the pixel circuit 110 according to the present embodiment shown in FIG. 4 has been described with reference to FIGS. 5 to 10 . In addition, although the case in which the P-channel type control transistors M1 and M3 are applied in the above-described example has been described, the control transistors M1 and M3 are not necessarily limited to the P-channel type transistors. As a specific example, the control transistors M1 and M3 may be configured as N-channel transistors. In that case, the relationship between the potentials of the respective signals can be appropriately changed in accordance with the characteristics of the respective transistors.

[2.4. Control of data signal for compensation]

An example of control of the compensation data signal Comp.Data in the display device 10 according to the present embodiment will be described.

As described above with reference to FIGS. 5 and 8 , in the third and fourth periods ( T ₁₃ and T ₁₄ , see FIG. 5 ) of one frame period, the gate voltage ( Vg) is determined based on the compensation data signal Comp.Data. In addition, in the third and fourth periods ( T ₁₃ and T ₁₄ , see FIG. 5 ), the gate voltage Vg is changed by the sensing current Is of the light sensors Ps1 and Ps2 in the fifth period T ₁₅ ) corresponds to the initial value of the gate voltage Vg. That is, the light emission period (particularly, the fifth period T ₁₅ ) of the organic EL element OLED is changed according to the initial value of the gate voltage Vg.

Also, the emission luminance of the organic EL device OLED is changed by the data signal Data according to the grayscale, and the sensing current Is flowing through the first optical sensor Ps1 also changes according to the change in the emission luminance.

As a specific example, when white (255 grayscale) is displayed, the emission luminance of the organic EL device OLED is increased. As the emission luminance increases, the sensing current Is flowing through the first optical sensor Ps1 increases, and the emission period of the organic EL device OLED decreases.

Compared to the case of displaying white (255 gradations), in the case of displaying an intermediate gradation (eg, 128 gradations) such as gray, the emission luminance of the organic EL device OLED is lowered and the luminance of light flowing through the first optical sensor Ps1 is lowered. The sensing current Is also decreases. Therefore, when displaying an intermediate gradation (eg, 128 gradation) such as gray compared to the case of displaying white (255 gradation), the emission period of the organic EL element OLED becomes longer (eg, 2 times) ) tends to be the length of

On the other hand, as shown above, if the light emission period of the organic EL element OLED is changed depending on the gradation to be displayed, the compensation accuracy is affected. This is because it is difficult to discriminate the light to be detected by the first optical sensor Ps1 from among the light emitted for gradation display and the light emitted for luminance deterioration compensation.

In consideration of such a situation, in the display device 10 according to the present embodiment, the compensation data signal Comp.Data is controlled according to the emission luminance (gradation). Here, an example of the control of the compensation data signal Comp.Data according to the emission luminance (gradation) will be described with reference to FIGS. 11 to 13 . 11 to 13 are explanatory diagrams for explaining an example of the control of the compensation data signal Comp.Data according to the emission luminance (gradation).

For example, FIG. 11 shows an example of a circuit configuration of a modeled pixel circuit in order to explain the control of the compensation data signal Comp.Data according to the emission luminance (grayscale). The pixel circuit illustrated in FIG. 11 further includes a configuration for supplying the data signal Comp.Data for compensation to the gate terminal of the control transistor EM-TFT compared to the pixel circuit described with reference to FIG. 1 .

That is, according to the pixel circuit shown in FIG. 11 , the compensation data signal Comp.Data supplied to the gate terminal of the control transistor EM-TFT is maintained in the sensor capacitance Cs. In addition, the compensation data signal Comp.Data held in the sensor capacitance Cs is discharged by the sensing current Is according to the detection result of the optical sensor Ps, and the control transistor EM is discharged by the sensor capacitance. -TFT), the potential of the gate terminal rises. Then, when the potential Vg of the gate terminal of the control transistor EM-TFT rises to the threshold voltage Vth of the control transistor EM-TFT, the control transistor EM-TFT is turned off. .

Here, reference is made to FIG. 12 . 12 shows the gate voltage ( EM-TFT) of the control transistor EM-TFT for each of the emission luminances (grayscale) when the voltage value of the compensation data signal Comp.Data is fixed without depending on the emission luminance (gradation) An example of the time series change of Vg) is shown. In the graph shown in FIG. 12 , the horizontal axis represents time t, and the vertical axis represents the gate voltage Vg of the control transistor EM-TFT. In addition, in the example shown in FIG. 12, the change of the gate voltage Vg according to time series is exemplarily shown for the case of displaying white (255 gradations) and the case of displaying intermediate gradations (128 gradations) such as gray. have. In addition, in the example shown in FIG. 12, it is assumed that the organic electroluminescent element OLED is a state (initial state) in which it is not deteriorated.

12, since the voltage value of the compensating data signal Comp.Data is constant and does not depend on the emission luminance (grayscale), the initial value of the gate voltage Vg of white (255 grayscale) and the intermediate grayscale The initial values of the gate voltages Vg of (128 gradations) are equal to each other. In addition, the voltage value Vginit of the gate voltage Vg shown in FIG. 12 has shown the initial value of the gate voltage Vg in the example shown in FIG.

As described above, the gate voltage Vg of the control transistor EM-TFT increases in time series from the initial value Vginit by the sensing current Is flowing through the optical sensor Ps. Then, when the gate voltage Vg reaches the threshold voltage Vth of the control transistor EM-TFT, the control transistor EM-TFT is switched to a turn-off state, and the organic EL element OLED is turned off. do.

At this time, as shown in FIG. 12 , the period during which the gate voltage Vg reaches the threshold voltage Vth depends on the emission luminance of the organic EL element OLED detected by the optical sensor Ps. For example, in the case where the organic EL device OLED displays a half gray scale (128 gray scale) compared to the case where the organic EL device OLED displays white (255 gray scale) as shown in FIG. 12 , the gate voltage Vg is the threshold voltage The time to reach (Vth) becomes longer (for example, it becomes twice as long).

13 exemplarily illustrates the time series change of the gate voltage Vg of the control transistor EM-TFT when the voltage value of the compensation data signal Comp.Data is controlled differently according to the emission luminance (grayscale) is indicating In addition, in the graph shown in FIG. 12, a horizontal axis and a vertical axis|shaft are the same as that of the graph shown in FIG. In the example shown in Fig. 13, similarly to the example shown in Fig. 12, both the case of displaying white (255 gradations) and the case of displaying intermediate gradations (128 gradations) such as gray are gated according to time series. An example of a change in the voltage Vg is shown. In addition, in the example shown in FIG. 13, let it be the state (initial state) in which the organic electroluminescent element OLED has not deteriorated.

In FIG. 13 , reference sign Vg ₁₂₈ indicates the gate voltage Vg of the control transistor EM-TFT according to the voltage value of the compensation data signal Comp.Data in the case of displaying the intermediate grayscale (128 grayscale). ) shows an example of the initial value. In addition, the reference sign Vg ₂₅₅ denotes an initial value of the gate voltage Vg of the control transistor EM-TFT according to the voltage value of the compensation data signal Comp.Data when white (255 grayscale) is displayed. shows an example of

In the example shown in Fig. 13, when white (255 gradations) and halftones (128 gradations) are displayed, the period until the gate voltage Vg of the control transistor EM-TFT reaches the threshold voltage Vth. The initial values Vg ₂₅₅ and Vg ₁₂₈ of the gate voltage Vg are adjusted so that (that is, the reference light emission period T ₅ in FIG. 13 ) becomes constant.

As a specific example, the amount of change of the gate voltage Vg per unit time may be doubled when white (255 grays) is displayed compared to when intermediate grays (128 grays) are displayed. In the case of displaying white (255 gradations), the gate voltage Vg is such that the amount of change in the gate voltage Vg until the threshold voltage Vth is reached is twice that of displaying the intermediate gradation (128 gradations). ) can be set to initial values (Vg ₂₅₆ and Vg ₁₂₈ ). Also, as shown in FIG. 13 , the initial value (Vg ₂₅₅ ) of the gate voltage Vg corresponding to white (255 grayscale) and the initial value (Vg128) of the gate voltage Vg corresponding to the intermediate grayscale ( ₁₂₈ grayscale) ) between Vg ₂₅₅ < Vg ₁₂₈ .

In addition, the initial value of the gate voltage Vg may be set so that the reference light emission period T ₅ is constant even for grayscales other than white (255 grayscale) and intermediate grayscale (128 grayscale). Of course, it is not necessary to set the initial value of the gate voltage Vg for all grayscales, and for some grayscales, the initial value of the gate voltage Vg may be calculated based on interpolation processing.

As described above, the compensation data signal Comp.Data is controlled according to the emission luminance (gradation), so that the emission period of the organic EL element OLED in the initial state (that is, before deterioration) is the emission luminance (gradation). It is controlled so that it becomes constant without being dependent on it. With such a configuration, since the light emission period of the organic EL element OLED does not affect the grayscale data, the display device 10 according to the present embodiment detects the amount of deterioration of the organic EL element OLED and detects the result of the detection. Accordingly, it becomes possible to extend the light emission period.

An example of the control of the compensation data signal Comp.Data in the display device 10 according to the present embodiment has been described above with reference to FIGS. 11 to 13 .

[2.5. organize]

As described above, the pixel circuit 110 according to the present embodiment includes the driving circuit 117 for controlling the luminance of the organic EL element OLED according to the data signal Data according to the emission luminance (gradation) and the driving system. A circuit group for correcting the amount of light emitted from the organic EL element OLED positioned at the rear end of the circuit 117 is provided. With such a configuration, the display device 10 according to the present embodiment independently controls the luminance control of the organic EL element OLED according to the emission luminance (gradation) and the compensation of the luminance deterioration of the organic EL element OLED. thing becomes possible

In addition, the discharge period of the sensor capacitance Cs changes in response to the detection result of the first optical sensor Ps1, and the gate voltage Vg of the control transistor M3 is controlled in response to the discharge of the sensor capacitance Cs. do. Accordingly, according to the pixel circuit 110 according to the present embodiment, the discharge period of the sensor capacitor Cs is extended corresponding to the amount of luminance deterioration of the organic EL element OLED, and as the discharge period is extended, the organic EL The light emission period of the device OLED (particularly, the fifth period T ₁₅ of FIG. 5 ) is extended. That is, according to the pixel circuit 110 according to the present embodiment, the light emission period of the organic EL element OLED is extended corresponding to the amount of luminance deterioration of the organic EL element OLED. As a result, the organic EL element OLED It becomes possible to compensate for the luminance deterioration of

In addition, the control according to the compensation of the luminance deterioration of the organic EL element OLED by the configuration of the pixel circuit 110 (refer to FIG. 4 ) and the control of the pixel circuit 110 ( FIGS. 5 to 10 ) shown above is performed by the pixel. Completion within the circuit 110 becomes possible.

In addition, in the pixel circuit 110 according to the present embodiment, the on/off of the control transistor M1 may be controlled by the on/off of the control transistor M3 in order to control the emission of the organic EL element OLED. . With such a configuration, in the pixel circuit 110 according to the present embodiment, the on/off time of the control transistor M1 can be controlled to be shorter.

In addition, in the display device 10 according to the present embodiment, since the deviation of the threshold voltage Vth of the control transistor M3 between the plurality of pixel circuits 110 is compensated, the threshold voltage Vth is The change in the switching timing of the control transistor M1 according to the change is controlled. That is, according to the display device 10 according to the present embodiment, it is possible to more precisely control the compensation light emission period according to the luminance deterioration of the organic EL element OLED.

With the above configuration, the display device 10 according to the present embodiment realizes, in a more preferable form, the luminance setting of the organic EL element OLED and the correction of the amount of light emitted according to the luminance deterioration amount of the organic EL element OLED. it becomes possible to do

<3. Second embodiment>

Next, the display device 10 according to the second embodiment of the present invention will be described. In addition, the display device 10 according to the second embodiment differs from the display device 10 according to the first embodiment in the configuration of the pixel circuit 110 and the driving timing of the pixel circuit 110 in particular. Therefore, in this description, the configuration of the pixel circuit 110 and the driving timing of the pixel circuit 110 will be focused on the description, and detailed description of other configurations will be omitted.

[3.1. Configuration of pixel circuit]

First, an example of the configuration of the pixel circuit 110 according to the second embodiment will be described with reference to FIG. 14 . 14 is an explanatory diagram for explaining an example of the configuration of the pixel circuit 110 according to the present embodiment. FIG. 14 shows an example of the pixel circuit 110 arranged in the nth row among the plurality of pixel circuits 110 constituting the display unit 100 shown in FIG. 3 . In addition, the other pixel circuits 110 constituting the display unit 100 may be the same as those of the pixel circuit 110 shown in FIG. 14 , and thus a detailed description thereof will be omitted.

14 , the pixel circuit 110 according to the present embodiment includes an organic EL element (OLED), a driving circuit 117 , control transistors M1 and M3 , switching transistors M2 , M4 , M25 , M26 , and M31), the optical sensors Ps1 and Ps2, a sensor capacitance Cs, and a capacitance C1.

Further, the driving circuit 117 , the control transistors M1 and M3 , and the organic EL element OLED shown in FIG. 14 are the driving circuit 117 and the control according to the first embodiment (see FIG. 4 ) described above. It corresponds to the transistors M1 and M3 and the organic EL element OLED. Similarly, the optical sensors Ps1 and Ps2, and the sensor capacitance Cs correspond to the optical sensors Ps1 and Ps2, and the sensor capacitance Cs, according to the above-described first embodiment (see FIG. 4 ). . In addition, the switching transistors M2, M4, and M31 and the capacitor C1 shown in FIG. 14 are the switching transistors M2, M4, and M31 according to the above-described first embodiment (refer to FIG. 4), and It corresponds to the capacity (C1).

14 , the driving circuit 117 is connected to the source terminal side of the control transistor M1, and the anode side of the organic EL element OLED is connected to the drain terminal side. Further, a power supply voltage ELVSS is connected to the cathode side of the organic EL element.

The driving circuit 117 is connected to the data line 114 via a switching transistor M31. The switching transistor M31 is turned on or off according to a Scan(n) signal transmitted through the scan line 112 . That is, as the switching transistor M31 is turned on (ie, conductive) based on the Scan(n) signal, the data signal Data transmitted through the data line 114 is transmitted to the driving circuit 117 . is supplied In addition, a power supply voltage is supplied to the driving circuit 117 from a power supply voltage ELVDD (not shown).

With this configuration, the driving circuit 117 receives the driving current Ic according to the data signal Data supplied through the data line 114 and the switching transistor M31 of the control transistor M1 positioned at the rear end. It is supplied to the source terminal.

The source terminal of the control transistor M3 is connected to the high potential power supply VDD through the switching transistor M25, and the drain terminal is connected to the gate terminal of the control transistor M1. The switching transistor M25 is turned on or turned off by a sense signal to be described later. In addition, the sense signal may be supplied to each pixel circuit 110 by, for example, the scan driver 120 . As long as it is possible to supply the sense signal at a predetermined timing to each pixel circuit 110, the source of the sense signal is not particularly limited.

Further, a signal line 115 for compensation is connected to the source terminal of the control transistor M3 via the switching transistor M26. The switching transistor M25 is turned on or off by a Scan(n-1) signal transmitted through the scan line 113 . That is, as the switching transistor M26 is turned on based on the Scan(n-1) signal, the compensation data signal Comp.Data transmitted through the compensation signal line 115 is transmitted to the control transistor M3. It is supplied to the source terminal.

Note that, hereinafter, a node to which the gate terminal of the control transistor M1 is connected is referred to as "node Nb" in some cases. In addition, the node to which the gate terminal of the control transistor M3 is connected is described as "node Na" in some cases.

One terminal of the capacitor C1 is connected to the node Nb, and the other terminal is connected to the high potential power supply VDD. In addition, a switching transistor M2 is interposed between the node Nb and the low potential power supply VGL. The switching transistor M2 is turned on or off by the initialization signal Init supplied through the initialization signal line 116 .

A switching transistor M4 is interposed between the drain terminal (in other words, the node Nb) of the control transistor M3 and the gate terminal (in other words, the node Na). The switching transistor M4 diode-connects the control transistor M3 by bypassing between the gate terminal and the drain terminal of the control transistor M3. A change in the threshold voltage of the control transistor M3 may be compensated for by the switching transistor M4 . The switching transistor M4 is turned on or off by a Scan(n-1) signal transmitted through the scan line 113 .

The optical sensor Ps1 (hereinafter, referred to as the first optical sensor) is provided so that a part of the light from the organic EL element OLED is irradiated. The first optical sensor Ps1 has one terminal connected to the node Na and the other terminal connected to the low potential power supply VGL.

The optical sensor Ps2 (hereinafter, referred to as a second optical sensor) is disposed to shield direct light from the organic EL device OLED. The second photosensor Ps2 detects noise light due to factors such as the structure of the pixel circuit 110 , that is, reflected light entering from the surroundings or light emitted from another pixel circuit 110 as a noise component. One terminal of the optical sensor Ps2 is connected to the node Na, and the other terminal is connected to the high potential power supply VDD. At this time, the optical sensors Ps1 and Ps2 are connected in series. With such a configuration, the sensing current Is flowing through the first optical sensor Ps1 is calculated based on the detection result of the first optical sensor Ps1, and the noise component is based on the detection result of the optical sensor Ps2. It is removed (cancelled).

As for the sensor capacitance Cs, one terminal is connected to the node Na, and the other terminal is connected to the low potential power supply VGL. The sensor capacitance Cs maintains the compensation data signal Comp.Data supplied to the node Na. The compensation data signal Comp.Data held in the sensor capacitance Cs is discharged according to the detection results of the optical sensors Ps1 and Ps2, and the gate voltage Vg of the control transistor M3 is discharged by the discharge. Controlled.

An example of the configuration of the pixel circuit 110 according to the present embodiment has been described above with reference to FIG. 14 .

[3.2. drive timing]

An example of driving timing of each element constituting the pixel circuit 110 according to the present embodiment shown in FIG. 14 will be described with reference to FIGS. 15 to 20 . 15 is a schematic timing chart for explaining an example of driving timing of the pixel circuit 110 according to the present embodiment. 16 to 20 are explanatory diagrams for explaining the connection relationship between elements constituting the pixel circuit 110 at each timing shown in FIG. 15 .

15 , the display device 10 according to the present embodiment divides one frame period into a plurality of periods T ₂₁ to T ₂₅ to drive the pixel circuit 110 . In addition, some of the periods T ₂ 1 to T ₂₅ correspond to the light emission period in which the organic EL element OLED emits light, and some of the periods T ₂₃ and T ₂₄ , T ₂₁ , T ₂₂ , and T ₂₅ ) correspond to the non-emission period in which the organic EL element OLED is turned off. 15 shows changes in the initialization signal Init, the Scan(n-1) signal, the Scan(n) signal, and the Sense signal in the periods T ₂₁ to T ₂₅ , and nodes Na and Nb ) shows the change in potential. In addition, the period indicated by the partial periods T ₂₁ and T ₂₂ corresponds to one horizontal scanning period 1H.

First, the first period T ₂₁ will be described. 16 illustrates a connection relationship between elements constituting the pixel circuit 110 in the first period T ₂₁ . During the first period T ₂₁ , the switching transistor M2 is turned on according to the initialization signal Init, and the switching transistors M4 and M26 are turned on according to the Scan(n-1) signal. switch to

As shown in Fig. 16, when the switching transistors M2 and M4 are switched to the turned-on state, the low potential power supply VGL is written to the gate terminal of the control transistor M3, and the gate terminal of the control transistor M3 is written. (In other words, the potential of the node Na) is initialized by the low potential power supply VGL. Then, as the gate terminal of the control transistor M3 is initialized by the low potential power supply VGL, the control transistor M3 is switched to the turn-on state. Also, at this time, the switching transistors M25 and M31 are in a turned-off state. In addition, the control transistor M1 is also turned off.

Next, the second period T ₂₂ will be described. 17 illustrates a connection relationship between elements constituting the pixel circuit 110 in the second period T ₂₂ . During the second period T ₂₂ , the switching transistor M2 is switched to a turn-off state by the initialization signal Init. Accordingly, the drain terminal (node Na) and the gate terminal (node Na) of the control transistor M3 are bypassed during the second period T ₂₂ . The so-called control transistor M3 is diode-connected.

The compensation data signal Comp.Data transmitted through the compensation signal line 115 is supplied to the source terminal of the control transistor M3 through the switching transistor M26. As a result, the potential of the gate terminal (node Na) of the control transistor M3 is adjusted to the potential Comp. Data reflecting the threshold voltage Vth of the control transistor M3 and the compensation data signal Comp.Data. -Vth). A change in the threshold voltage Vth of the control transistor M3 of the plurality of pixel circuits 110 is compensated for by such control.

Next, the third period T ₂₃ will be described. 18 illustrates a connection relationship between elements constituting the pixel circuit 110 in the third period T ₂₃ . During the third period T ₂₃ , the switching transistor M31 is switched to the turn-on state by the Scan(n) signal. Accordingly, the data signal Data transmitted through the data line 114 is supplied to the driving circuit 117 .

Also, during the third period T ₂₃ , the switching transistor M2 is switched to a turn-on state by the initialization signal Init. In addition, the switching transistors M26 and M4 are switched to the turn-off state by the Scan(n-1) signal. Thereby, the low potential power supply VGL is written to the gate terminal (node Na) of the control transistor M1, and the control transistor M1 is switched to the turn-on state.

Also, during the third period T ₂₃ , the switching transistor M25 is switched to a turn-on state by the Sense signal. Thereby, the source terminal of the control transistor M3 is connected to the high potential power supply VDD.

Based on the above control, the driving current Ic according to the data signal Data from the driving circuit 117 is supplied to the organic EL element OLED through the control transistor M1, and the organic EL element OLED is emitted with a luminance according to the driving current Ic.

Next, the fourth period T ₂₄ will be described. 19 shows the connection relationship of each element constituting the pixel circuit 110 during the period T ₂₄ . During the fourth period T ₂₄ , the switching transistor M2 is switched to a turn-off state by the initialization signal Init.

When the switching transistor M2 is turned into a turn-off state, the gate terminal (node Na) of the control transistor M3 is floated, and compensation data in which the threshold voltage Vth is compensated for the sensor capacitance Cs The signal Comp. Data-Vth is maintained. In addition, as the organic EL element OLED emits light, a sensing current Is flows through the optical sensor Ps1. The compensation data Data-Vth held in the sensor capacitance Cs is discharged by the sensing current Is, and the gate voltage Vg of the control transistor M3 is lowered by the discharge.

Next, the fifth period T ₂₅ will be described. 20 illustrates a connection relationship between elements constituting the pixel circuit 110 during the fifth period T ₂₅ . In the state shown in FIG. 20 , the gate voltage Vg of the control transistor M3 is adjusted to the threshold voltage Vth of the control transistor M3 by the sensing current Is based on the detection result of the optical sensors Ps1 and Ps2. ) is reached, and the control transistor M3 switches to the turn-on state. Thereby, the high potential power supply VDD is written to the gate terminal (node Nb) of the control transistor M1, and the control transistor M1 is switched to a turn-off state. As a result, the driving current Ic supplied from the driving circuit 117 to the organic EL element OLED is cut off, and the organic EL element OLED is turned off.

An example of driving timing of each element constituting the pixel circuit 110 according to the present embodiment shown in FIG. 14 has been described with reference to FIGS. 15 to 20 . In the example described above, the control transistors M1 and M3 have been exemplarily described as the P-channel control transistors M1 and M3, but the control transistors M1 and M3 are not limited to the P-channel transistor. . As a specific example, the control transistors M1 and M3 may be configured as N-channel transistors. In that case, the relationship between the potentials of the respective signals can be appropriately changed in accordance with the characteristics of the respective transistors.

[3.3. organize]

The display device 10 according to the present embodiment has the same effects as those of the display device 10 according to the first embodiment, based on the circuit configuration of the pixel circuit 110 and the control of the pixel circuit 110 described above. It is possible to represent

That is, the pixel circuit 110 according to the present embodiment includes a driving circuit 117 and a driving circuit 117 for controlling the luminance of the organic EL element OLED according to the data signal Data according to the emission luminance (gradation). and a circuit group for correcting the amount of light emitted from the organic EL element (OLED) positioned at the rear end of the . With such a configuration, the display device 10 according to the present embodiment can control the luminance of the organic EL element OLED according to the emission luminance (gradation) and compensate for the luminance deterioration of the organic EL element OLED. can be controlled The above two controls can be implemented independently.

In addition, referring to the circuit group located at the rear end of the driving circuit 117, the discharge period of the sensor capacitor Cs changes according to the detection result of the optical sensor Ps1, and is controlled by the discharge of the sensor capacitor Cs. The gate voltage Vg of the transistor M3 is controlled. Accordingly, in the pixel circuit 110 according to the present embodiment, the discharge period of the sensor capacitor Cs is extended corresponding to the amount of luminance deterioration of the organic EL element OLED, and the extension of the discharge period causes the organic EL element The light emission period of (OLED) (in particular, period T ₂₄ in FIG. 15 ) is extended. That is, according to the pixel circuit 110 according to the present embodiment, since the light emission period of the organic EL element OLED is extended corresponding to the amount of luminance deterioration of the organic EL element OLED, the luminance of the organic EL element OLED is extended. It becomes possible to compensate for deterioration.

In addition, by the configuration of the pixel circuit 110 ( FIG. 14 ) and the control of the pixel circuit 110 ( FIGS. 15 to 20 ) shown above, the control according to the compensation of the luminance deterioration of the organic EL element OLED is performed by the pixel. Completion within the circuit 110 becomes possible.

In addition, in the pixel circuit 110 according to the present exemplary embodiment, switching of the control transistor M1 for controlling light emission of the organic EL device OLED may be controlled by switching of the control transistor M3 . With such a configuration, in the pixel circuit 110 according to the present embodiment, the switching time of the control transistor M1 is controlled to be shorter.

In addition, in the display device 10 according to the present embodiment, the change in the threshold voltage Vth of the control transistor M3 is compensated for between the plurality of pixel circuits 110 , so that the threshold voltage Vth The change in the switching timing of the control transistor M1 according to the change is controlled. That is, according to the display device 10 according to the present embodiment, it is possible to control the compensation light emission period due to the deterioration of the luminance of the organic EL element OLED with high precision.

In addition, in the pixel circuit 110 (refer to FIG. 8 ) according to the first embodiment described above, the compensation data signal Comp.Data is written to the gate terminal of the control transistor M3 through the capacitor C2 . In contrast, in the pixel circuit 110 (refer to FIG. 17 ) according to the present embodiment, the compensating data signal Comp.Data is applied to the gate terminal of the control transistor M3 by the switching transistor M26 and the control transistor M3. lighted through With such a configuration, the number of capacitor elements in the pixel circuit 110 according to the present embodiment is reduced compared to the pixel circuit 110 according to the first embodiment described above. In general, the area occupied by the capacitor element in the pixel circuit tends to be larger than that of other elements. Therefore, in some cases, the pixel circuit 110 according to the present embodiment can be further downsized as compared to the pixel circuit 110 according to the first embodiment described above.

<4. Organize>

As mentioned above, although preferred embodiment of this invention was described in detail, referring an accompanying drawing, this invention is not limited to this example. For those of ordinary skill in the art to which the present invention belongs, within the scope of the technical idea described in the claims, it is clear that it is obtained by paying attention to each type of change or modification, and also about these, Naturally, it is construed as belonging to the technical scope of the present invention.

10 display unit 100 display unit
110 pixel circuit 112 scan line
113 scan line 114 data line
115 Compensation signal line 116 Initialization signal line
117 drive circuit 120 scan driver
130 data driver

Claims (11)

A display device including pixel circuits arranged in a matrix, the display device comprising:
The pixel circuit is
a light emitting device emitting light having a luminance according to an amount of current;
a driving circuit for controlling an amount of current supplied to the light emitting device in response to the applied first voltage;
a first transistor for switching an electrical connection between the light emitting device and the driving circuit in response to a first gate voltage applied to a first control terminal;
a first optical sensor detecting the luminance of the light emitted from the light emitting device;
a capacity for maintaining a second voltage reflecting the first voltage; and
a second transistor providing the first gate voltage to the first transistor;
the second transistor is turned on in response to a second gate voltage determined by the detected light luminance and the second voltage maintained at the capacitance;
the first transistor is turned off in response to the first gate voltage applied when the second transistor is turned on;
the first transistor includes the first control terminal, a first terminal, and a second terminal;
the second transistor includes a second control terminal, a third terminal, and a fourth terminal;
the third terminal of the second transistor is connected to the first control terminal of the first transistor;
and one terminal of the first optical sensor and one terminal of the capacitor are each connected to the second control terminal of the second transistor. The method of claim 1,
The discharge period of the second voltage maintained in the capacitance is controlled according to the luminance of the detected light,
A display device in which a light emission period of the light emitting element is controlled based on the discharge period. delete The method of claim 1,
and a second optical sensor connected in series to the first optical sensor and connected in parallel with respect to the capacitance and to which the light emitted from the light emitting element is not directly applied, wherein the discharge period of the second voltage is the first optical sensor and a result of detection of the second optical sensor. The method of claim 1,
Further comprising a first switching element for switching the electrical connection between the second control terminal and the third terminal,
The second transistor and the first switching element are turned on during a preparation period defined before the light emission period of the light emitting element, and the second control terminal has a potential reflecting the threshold voltage of the second transistor;
The display device of claim 1, wherein the threshold voltage is compensated for the second voltage. 6. The method of claim 5,
The display device of claim 1 , wherein a potential of the second control terminal of the second transistor is changed from a value to which a threshold voltage is not reflected to a value to which a threshold voltage is reflected during the preparation period. 6. The method of claim 5,
a second dose; and
a second switching element providing the second voltage to one terminal of the capacitor;
further comprising,
the second capacitor is interposed between the second switching element and one terminal of the capacitor;
When the second switching element is turned on, the second voltage is applied to the one terminal of the capacitor through the second capacitor. 8. The method of claim 7,
and after the second control terminal of the second transistor has a potential reflecting a threshold voltage of the second transistor, the second switching element is turned on. 6. The method of claim 5,
Further comprising a third switching element for providing the second voltage to the fourth terminal of the second transistor,
When the second transistor, the first switching element, and the third switching element are turned on, the second voltage is applied to the second control terminal of the second transistor, so that the second control terminal is connected to the second control terminal. 2 A display device, characterized in that it has a potential to which the threshold voltage of the transistor is reflected. 10. The method of claim 9,
and the third switching element is switched in synchronization with the first switching element. A method for displaying an image of a display device including pixel circuits arranged in a matrix, the method comprising:
The pixel circuit is
a light emitting device emitting light having a luminance according to an amount of current;
a driving circuit for controlling an amount of current supplied to the light emitting device in response to the applied first voltage;
a first transistor for switching an electrical connection between the light emitting device and the driving circuit in response to a first gate voltage applied to a first control terminal;
a first optical sensor detecting the luminance of the light emitted from the light emitting device;
a capacity for maintaining a second voltage reflecting the first voltage; and
a second transistor providing the first gate voltage to the first transistor;
turning on the second transistor based on a second gate voltage determined by the luminance of light detected by the first optical sensor and the second voltage maintained in the capacitance; and
turning off the first transistor based on the first gate voltage applied when the second transistor is turned on;
the first transistor includes the first control terminal, a first terminal, and a second terminal;
the second transistor includes a second control terminal, a third terminal, and a fourth terminal;
the third terminal of the second transistor is connected to the first control terminal of the first transistor;
One terminal of the first optical sensor and one terminal of the capacitor are each connected to the second control terminal of the second transistor.

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