JP2008181005A - Luminance characteristic correction device, electroluminescence display device, electronic equipment, luminance characteristic correction method, and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that luminance control considering the drive temperature characteristics of a light emitting element is not carried out. <P>SOLUTION: A luminance characteristics correction device corrects the luminance characteristics of an EL (electroluminescence) panel having pixel circuits 1 laid in a matrix, each having an EL element as a light emitting element, and the correction device is provided with (a) a cathode potential determining unit determining a cathode potential value to be applied to the cathode terminal of the EL element according to the current value of a drive temperature so that the potential change appearing at the current output terminal during a lighting period is kept constant regardless of changes in the drive temperature of the EL element when the pixel data are the same; and (b) a cathode potential varying unit applying the cathode potential corresponding to the cathode potential value to the cathode terminal of the EL element. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The invention described in this specification relates to a technique for correcting luminance characteristics of an EL panel caused by temperature characteristics of an EL (Electro Luminescence) element.
Note that the invention has aspects as a luminance characteristic correction device, an EL display device, an electronic apparatus, a luminance characteristic correction method, and a computer program.

  It is known that the current-voltage (IV) characteristics of the EL element, which is an important parameter during light emission, are affected by the driving temperature. However, the driving temperature of the EL element is easily affected by the environmental temperature and the heat generation of the EL element itself. For this reason, it is known that the current-voltage (IV) characteristics of the EL element always fluctuate.

  This variation in driving temperature acts as one of the factors that change the light emission luminance of the EL element. For example, even when the EL element is driven at a constant current, the emission luminance changes when the driving temperature changes and the voltage applied between the two electrodes of the EL element changes.

  Hereinafter, although the idea is different from the invention proposed by the inventors, some techniques that can change the light emission luminance (peak luminance level) of the display panel will be exemplified.

JP 2003-134418 A JP-A-2002-351389 discloses a technique for controlling peak luminance in accordance with average luminance of an input image. However, in these techniques, the influence of the temperature change of the EL element is not taken into consideration.

JP-A-2004-109170 discloses a technique for controlling peak luminance in accordance with the brightness of external light. However, even in this technique, the influence of the temperature change of the EL element is not taken into consideration.

JP-A-2003-330419 discloses a technique for referring to temperature characteristics of voltage-current characteristics of a light-emitting element and correcting display data so that appropriate luminance is obtained with respect to detected ambient temperature. Is disclosed. However, the correction of display data leads to the loss of gradation information and has a problem of degrading image quality.

In this patent document, a technique is disclosed in which the cathode potential is controlled according to the brightness of external light to reduce the voltage between Vcc and the cathode potential, and as a result, the peak luminance is lowered. Yes.

  However, in the case of this patent document, only the use of variable control of the cathode potential for changing the Vd-Id characteristic of the thin film transistor is considered, and no influence is given to the influence of the temperature characteristic of the EL element.

  As described above, neither patent document discloses nor suggests correction of the luminance characteristics of the EL panel in consideration of the temperature change of the EL element.

  The inventors include an EL (Electro Luminescence) element, a current driving element that drives the EL element in current, and a storage circuit that stores a charge corresponding to pixel data between a control terminal and a current output terminal of the current driving element. As a luminance characteristic correction apparatus that corrects the luminance characteristics of an EL panel in which pixel circuits having the above are arranged in a matrix, a device having the following processing function unit is proposed.

(A) If the pixel data is the same, the potential of the EL element depends on the current value of the drive temperature so that the potential appearing at the current output terminal during the lighting period is constant regardless of the change in the drive temperature of the EL element. A cathode potential determining unit for determining a cathode potential value applied to the cathode terminal; and (b) a cathode potential generating unit for applying a cathode potential corresponding to the cathode potential value to the cathode terminal of the EL element.

  According to the invention proposed by the inventors, it is possible to realize a display technique in which the change in display luminance is small even when the driving temperature of the EL element changes depending on the use environment or the like.

Hereinafter, a case where the invention is applied to an active matrix drive type organic EL display device (EL display device) will be described.
In addition, the well-known or well-known technique of the said technical field is applied to the part which is not illustrated or described in particular in this specification.
Moreover, the form example demonstrated below is one form example of invention, Comprising: It is not limited to these.

(A) Principle of correcting luminance characteristic (a) Cause of deterioration of luminance characteristic Here, the cause of deterioration of the luminance characteristic, which has been a problem in the past, will be described.
FIG. 1 shows a structural example of a pixel circuit in which the same problem occurs.

The pixel circuit 1 includes a switch element T1, a capacitor C, a current driving element T2, a duty control element T3, a reset element T4, and an organic EL element D.
The switch element T1 is a thin film transistor that controls the writing of the signal voltage Vsig corresponding to the pixel data to the capacitor (storage circuit) C.

  Here, the pixel data is given from the data line driver through the data line DL. The opening / closing operation of the switch element T1 is controlled by a write signal WS supplied from the scanning line driver through the scanning line WL.

  The signal voltage Vsig written to the capacitor C is held between the gate terminal and the drain terminal of the current driving element T2 until a new signal voltage Vsig is written in the next frame.

  For this reason, the current driving element T2 formed of an N-channel type thin film transistor operates so as to supply the organic EL element D with a driving current having a magnitude determined by the signal voltage Vsig (= Vgd) held in the capacitor C. To do.

  The duty control element T3 is a thin film transistor that controls the lighting time ratio (duty) in one frame of the organic EL element D. The duty control element T3 is connected in series to the organic EL element D, and controls the supply and stop of the drive current supplied from the current drive element T2 to the organic EL element D.

The control signal Sds of the duty control element T3 is supplied from the duty line control driver through the duty control line.
The reset element T4 is a transistor that resets the anode potential (drain potential Vd) of the organic EL element D to the fixed potential Vrs when the signal voltage Vsig is written. The control signal Srs for the reset element T4 is supplied through a reset line.

FIG. 2 shows a temperature change of the source-gate voltage of the current driving element T2 by a general driving method conventionally used.
A solid line indicates a change in potential when the driving temperature of the organic EL element D is low. On the other hand, a broken line shows a change in potential when the driving temperature of the organic EL element D is high.

As shown in FIG. 2, as the light emission of the organic EL element D starts, a voltage V _EL corresponding to the drive current is generated between both electrodes of the EL element D, and the rise of the drain potential Vd is started. At this time, the gate potential Vg also starts to rise so as to be pushed up to the rising drain potential Vd.

  However, a potential loss inevitably occurs when the drain potential Vd increases. The cause is an influence of parasitic capacitance existing around the capacitor C. That is, even if the signal voltage Vsig is changed while being held in the capacitor C, a part of the charge held in the capacitor C escapes to the parasitic capacitance. As a result, the gate-drain voltage Vgd 'after light emission becomes smaller than that at the time of writing.

This change in the gate-drain voltage Vgd can be expressed by the following equation when the potential amount that can be maintained in the capacitor C when the potential rises during light emission is expressed by a gain Gb (<1).
Vgd '= Vgd- (1-Gb) .a
Note that the variable a means the rising voltage of the drain potential Vd when the potential is rising.

From the previous equation, it can be seen that the smaller the rising voltage (variable a) of the drain potential Vd, the smaller the change in the gate-drain voltage Vgd before and after the start of light emission.
Further, from the previous equation, it can be seen that if the rising voltage (variable a) of the drain potential Vd is constant regardless of the driving temperature, the temperature characteristic does not appear in the screen luminance.

However, as shown in FIG. 3, the voltage V _EL generated between both electrodes of the organic EL element D (voltage between both electrodes) V _EL changes greatly when the driving temperature is different even if the driving current I d is the same. As shown in FIG. 3, the higher the drive temperature, the smaller the voltage V _EL between the electrodes.
However, in the case of the conventional driving method (FIG. 2), the cathode potential Vcathode applied to the cathode terminal of the organic EL element D is fixed.

  For this reason, when the driving temperature is different, as shown in FIG. 2, a phenomenon occurs in which the variable a that gives the rising voltage of the drain potential Vd changes. That is, even when the signal voltage Vsig corresponding to the same pixel data is written in the capacitor C, a phenomenon occurs in which the light emission luminance changes according to the driving temperature.

  FIG. 4 shows the drive temperature characteristics of the light emission luminance. As shown in FIG. 4, a phenomenon occurs in which the light emission luminance of the organic EL element increases as the driving temperature increases, and the light emission luminance of the organic EL element decreases as the driving temperature decreases. In FIG. 4, the light emission luminance at each drive temperature is normalized by assuming that the light emission luminance is 1 when the drive temperature is normal temperature (about 20 ° C.).

(B) Principle of the correction method proposed by the inventors Accordingly, the inventors have responded to changes in the drive temperature in order to stabilize the screen brightness regardless of changes in the drive temperature that inevitably occur depending on the use environment or the like. Then, a method for variably controlling the cathode potential Vcathode applied to the cathode terminal of the organic EL element D is proposed.

Specifically, a method is proposed in which the rising voltage (variable a) of the drain potential Vd generated after the organic EL element D is turned on becomes constant regardless of the driving temperature.
First, the driving temperature characteristics of the voltage V _EL between the electrodes of the organic EL element D will be considered. The drive temperature characteristic varies depending on the type of the organic EL element D, but has a linear relationship as shown in FIG.

That is, the higher the driving temperature, the smaller the voltage V _EL between the two electrodes of the organic EL element D. In FIG. 5, the voltage V _EL between the electrodes at room temperature is “1”, and the voltage V _EL between the electrodes at each temperature is relatively represented.

The inventors variably control the cathode potential Vcathode applied to the cathode terminal of the organic EL element D according to the driving temperature so as to cancel the driving temperature characteristic of the voltage V _EL between both electrodes of the organic EL element D. FIG. 6 shows drive temperature characteristics required for the cathode potential Vcathode.

  As shown in FIG. 6, by controlling the cathode potential Vcathode, the rising voltage after the start of lighting appearing in the drain potential Vd of the current driving element T2 has a substantially constant characteristic regardless of the driving temperature as shown in FIG. As shown. As a result, if the same pixel data is written, the screen brightness can be kept constant regardless of the drive temperature.

(B) Embodiment 1 of display device to which correction principle is applied
Hereinafter, an example of a display device to which the above-described correction principle is applied will be described.

(B-1) Overall Configuration of Display Device FIG. 8 shows the main components of the organic EL display device 11. The organic EL display device 11 includes an organic EL panel 13, a data line driver 15, a scanning line driver 17, a lighting period driver 19, a reset driver 21, a luminance characteristic correction unit 23, and a timing generator 25 as main components.

  The organic EL panel 13 is a self-luminous display panel in which the pixel circuits 1 (FIG. 1) are arranged in a matrix according to the panel resolution. In the case of this embodiment, the organic EL panel 13 is for color display, and the pixel circuit 1 is arranged for each emission color.

  However, when the organic EL element D having a structure in which a plurality of light emitting layers are stacked constitutes the pixel circuit 1, one pixel corresponds to a plurality of light emission colors. A specific connection relationship between the pixel circuit 1 and the driving circuit is shown in FIG.

  The data line driver 15 is a circuit device that applies a signal voltage Vsig corresponding to pixel data to the data line DL to which the pixel circuit 1 to be written is connected. Application of the signal voltage Vsig to each data line DL is executed in units of horizontal scanning periods.

  The scanning line driver 17 is a circuit device that provides a write timing of the signal voltage Vsig. The scanning line driver 17 selects one scanning line WL every time the horizontal synchronization signal HS is input, and controls the pixel circuit 1 located on the scanning line WL to a writable state. This control signal is the write signal WS.

The lighting period driver 19 is a circuit device that actually controls the lighting time ratio of the organic EL element D within one frame period. This control signal is the duty control signal Sds.
The reset driver 21 is a circuit device that resets the anode potential (drain potential Vd) of the organic EL element D to the reset potential Vrs when the signal voltage Vsig is written. This control signal is the reset signal Srs.

The luminance characteristic correction unit 23 is a circuit device that controls the cathode potential Vcathode applied to the cathode terminal of the organic EL element D so as to cancel the driving temperature characteristic of the voltage V _EL between the electrodes of the organic EL element D.

FIG. 10 shows an internal configuration example of the luminance characteristic correction unit 23. The luminance characteristic correction unit 23 includes a temperature detection unit 31, a cathode potential determination unit 33, and a cathode potential variable unit 35.
The temperature detection unit 31 is a temperature sensor that detects the driving temperature of the organic EL element D.

  In the case of this embodiment, the surface temperature of the organic EL panel 13 is substituted for the driving temperature of the organic EL element D. For this reason, the temperature detection part 31 is arrange | positioned as close to the effective display area as possible. For example, it arrange | positions to the outer peripheral part of an effective display area, the back surface side of the organic EL panel 13, etc. with respect to an effective display area.

  The cathode potential determination unit 33 is a processing device that refers to the reference table that realizes the control characteristics described with reference to FIG. 6 and determines an optimum cathode potential for the detected drive temperature. FIG. 11 shows an example of a reference table referred to by the cathode potential determination unit 33.

  In the case of the reference table shown in FIG. 11, the cathode potential determination unit 33 determines the cathode potential Vcathode (digital value) corresponding to the driving temperature of −10 ° C. to 1V. Further, the cathode potential determining unit 33 determines the cathode potential Vcathode corresponding to the driving temperature of 60 ° C. to 3V.

  The cathode potential variable unit 35 is a circuit device that variably controls the potential supplied to the cathode terminal of the organic EL element D so as to become the determined cathode potential Vcathode. FIG. 12 shows an internal configuration example of the cathode potential variable unit 35.

  The cathode potential variable unit 35 shown in FIG. 12 includes a digital potentiometer 41 and a voltage follower circuit (an operational amplifier OP1, resistors R11 and R13, and a PNP bipolar transistor T11) 43. The digital potentiometer 41 is composed of a semi-fixed resistor that generates a voltage in 256 steps (8 bits), for example.

  The timing generator 25 is a circuit device that supplies timing signals to the various drivers described above based on the pixel data Din. The timing generator 25 supplies, for example, a horizontal synchronization signal, a vertical synchronization signal, an operation clock, and the like.

(B-2) Drive Operation of Display Device Hereinafter, the drive operation executed by the organic EL display device 11 having the above-described functional configuration will be described. FIG. 13 shows a drive signal waveform of a certain pixel circuit 1 and a change in potential in the pixel circuit.

(A) Operation in Write Period First, the drive operation in the pixel data write period will be described. At this time, the signal voltage Vsig (FIG. 13A) is applied to the data line DL from the start of the corresponding horizontal scanning period. Here, the start point of the horizontal scanning period is given by the horizontal synchronization signal HS (FIG. 13B).

  At this time, the “H” level write signal WS (FIG. 13C) is applied to the scanning line WL, and the switch element T1 is turned on. As a result, the signal voltage Vsig can be written to the capacitor C.

  When the signal voltage Vsig is written, the potential on the other end side of the capacitor C is controlled to the reset potential Vrs. This is because if the potential at the other end of the capacitor C is indefinite, the voltage written to the capacitor C does not become the same as the original signal voltage Vsig. Therefore, the reset signal Srs (FIG. 13D) is controlled to the “H” level in accordance with the writing of the signal voltage Vsig.

  As a result, the gate potential Vg (FIG. 13E) of the current driving element T2 in the writing period starts to rise as the writing voltage increases. On the other hand, the drain potential Vd (FIG. 13F) of the current driving element T2 during the same period is held at the reset potential Vrs.

  In addition, the duty control signal Sds (FIG. 13G) during the writing period is controlled to the “L” level. As a result, the duty control element T3 is turned off.

(B) Operation during Lighting Period Next, the driving operation during the lighting period of the organic EL element D will be described. At this time, the signal voltage Vsig (FIG. 13A) corresponding to the next scanning line WL is applied to the data line DL from the start of the corresponding horizontal scanning period.

  However, since the “L” level write signal WS (FIG. 13C) is applied to the scanning line WL, the switch element T1 of the pixel circuit 1 currently focused on is controlled to be off. That is, the data line DL and the pixel circuit 1 are controlled to be electrically separated.

  In the case of this embodiment, the duty control signal Sds (FIG. 13G) is switched to the “H” level immediately after the end of the writing period. For this reason, the current drive element T2 starts to supply a drive current according to the signal voltage Vsig stored in the capacitor C.

Along with the supply of the drive current, a voltage V _EL between both electrodes is generated between both electrodes of the organic EL element D, and gradually increases with time. Along with this, the drain potential Vd (FIG. 13F) of the current driving element T2 starts to gradually increase from the reset potential Vrs.

Further, the gate potential Vg (FIG. 13E) starts to increase in accordance with a predetermined gain Gb so as to be linked to the increase of the drain potential Vd (FIG. 13F).
However, in the case of this embodiment, the cathode potential Vcathode is controlled according to the driving temperature of the organic EL element D so that the rising voltage (variable a) after the start of lighting is the same if the pixel data is the same. Yes.

FIG. 14 shows the state of this control operation. As shown in FIG. 14, even if the interpolar voltage V _EL generated between both electrodes of the organic EL element D fluctuates according to the driving temperature, the cathode potential Vcathode so as to cancel the fluctuation amount.
Is controlled to increase or decrease.
Therefore, as shown in FIG. 14, the rising voltage (variable a) of the drain potential Vd after the start of lighting becomes substantially constant even when the driving temperature changes.

  As a result, even when the driving temperature is different, the temperature-dependent characteristic of the holding voltage Vgd ′ of the capacitor C after the start of lighting is eliminated. If the value of the pixel data Din is the same, the organic EL element D always has the same emission luminance. It becomes possible to control lighting.

(C) Operation during Light-Off Period During the light-out period, the duty control signal Sds is again driven and controlled to the “L” level. As a result, the supply of drive current to the organic EL element D is stopped. That is, the light emission luminance of the organic EL element D decreases with a decrease in the drive current and eventually turns off.

If no drive current flows through the organic EL element D, the voltage V _EL is not generated between the two electrodes. Accordingly, as shown in FIG. 13F, the drain potential Vd of the current driving element T2 is lowered. Further, as the drain potential Vd decreases, the gate potential Vg (FIG. 13 (F)) of the current driving element T2 also decreases.

(B-3) Effect of Embodiment As described above, in the organic EL display device according to this embodiment, the same luminance level is obtained as long as the pixel data values are the same regardless of the driving temperature of the organic EL element D. Can be maintained.

That is, the display brightness of the organic EL panel 13 can be controlled to be constant. Therefore, it is possible to realize an organic EL display device whose image quality does not change due to a temperature change.
In particular, high effects can be expected in the case of mobile applications and large screen type organic EL display devices that are easily affected by environmental temperature.

  Further, in the case of the organic EL display device according to this embodiment, since the emission luminance maintenance control is realized by the control of the cathode potential Vcathode, there is no possibility that the gradation information is lost unlike the case where the pixel data Din is subjected to gamma conversion. . For this reason, high image quality can be maintained.

(C) Embodiment 2 of display device to which correction principle is applied
Hereinafter, another embodiment of the display device to which the above-described correction principle is applied will be described. Here, a case where the driving temperature of the organic EL element D is directly detected from the target pixel will be described.

(A) Case of Detecting Driving Temperature Using Dummy Pixel with Same Structure FIG. 15 shows a structural example of the organic EL panel 51. In the case of this embodiment, a dummy pixel area 55 dedicated for measurement is arranged outside the effective display area 53. Note that the number of pixels constituting the dummy pixel region 55 is arbitrary. Basically, if there is one dummy pixel, the driving temperature can be detected.

  15A shows an example in which the dummy pixel area 55 is arranged on the outer periphery in the horizontal direction of the effective display area 53, and FIG. 15B shows an example in which the dummy pixel area 55 is arranged on the outer periphery in the vertical direction of the effective display area 53. An example is shown. The pixel structure of the dummy pixel area 55 is the same as the pixel structure of the effective display area 53. Therefore, the effective display area 53 is integrally formed by the same process.

  FIG. 16 shows the main components of the organic EL display device 61 in this embodiment. In FIG. 16, the same reference numerals are given to the portions corresponding to those in FIG. 8. As shown in FIG. 16, the basic configuration is the same as the configuration described in FIG.

  16 includes an organic EL panel 51, a data line driver 15, a scanning line driver 17, a lighting period driver 19, a reset driver 21, a timing generator 25, a luminance characteristic correction unit 63, and a temperature detection unit 65. The main component.

  The luminance characteristic correction unit 63 in this embodiment corresponds to the cathode potential determination unit 33 and the cathode potential variable unit 35 in the luminance characteristic correction unit 23 described with reference to FIG. On the other hand, the temperature detection unit 65 corresponds to the temperature detection unit 31 in the luminance characteristic correction unit 23 described with reference to FIG.

  FIG. 17 shows a specific connection relationship between the dummy pixel circuit 71 constituting the dummy pixel region 55 and the drive circuit. As shown in FIG. 17, the connection relationship other than the temperature detection unit 65 is the same as the connection relationship described in FIG. That is, the dummy pixel circuit 71 is also driven by the same driving method as the pixel circuit 1 in the effective display area 53.

In the case of this embodiment, the driving temperature of the dummy pixel circuit 71 is realized by detecting the interpolar voltage V _EL appearing between both electrodes of the organic EL element D. For this reason, the anode potential Vs and the cathode potential Vcathode of the organic EL element D are given to the temperature detection unit 65.

  FIG. 18 shows an internal configuration example of the temperature detection unit 65. In the case of this embodiment, the temperature detection unit 65 includes a dummy pixel data generation unit 71, a dummy pixel data insertion unit 73, and a temperature conversion unit 75.

  The dummy pixel data generation unit 71 is a circuit device that generates dummy pixel data having a constant gradation value for temperature detection. In this embodiment, a fixed value set in advance is used for the dummy pixel data.

  The dummy pixel data insertion unit 73 is a circuit device that inserts dummy pixel data into input pixel data. The insertion position of the dummy pixel data depends on the arrangement position of the dummy pixel area. As described above, the insertion position is different between the case where the effective display area is arranged on the outer periphery in the horizontal direction and the case where the effective display area is arranged on the outer periphery in the vertical direction.

  The temperature conversion unit 75 is a circuit device that converts a voltage detected during the lighting period of the organic EL element D into a driving temperature. FIG. 19 illustrates an internal configuration example of the temperature conversion unit 75. As shown in FIG. 19, the temperature conversion unit 75 includes a voltage follower circuit 81, an analog / digital conversion circuit (A / D conversion circuit) 83, a differential voltage calculation unit 85, and a temperature information output unit 87.

Here, the voltage follower circuit 81 is used because the magnitude of the drive current supplied to the organic EL element D is very small (nano order). This is because it is difficult to detect a change in the voltage V _EL between the electrodes using such a minute driving current.

The potential detected through the voltage follower circuit 81 is converted into a digital value by the analog / digital conversion circuit 83.
The difference voltage calculation unit 85 executes a process of calculating a difference voltage between the anode potential (drain potential Vd) and the cathode potential Vcathode of the organic EL element D detected during the lighting period of the organic EL element D.

By this calculation process, the interpolar voltage V _EL generated between both electrodes of the organic EL element D is calculated. The reason why such calculation processing is performed is that in the case of this embodiment, the pixel circuit 71 in the dummy pixel region adopts the same circuit configuration as the pixel circuit 1 in the effective display region. That is, the cathode potential Vcathode of the organic EL element D is variably controlled. Therefore, a method of calculating a difference value between potentials corresponding to both electrodes of the organic EL element D is employed.

The temperature information output unit 87 is a circuit device that reads and outputs temperature information corresponding to the calculated potential difference from the reference table.
FIG. 20 shows an example of the reference table. This reference table is obtained by measuring in advance the temperature characteristics of the interpolar voltage V _EL generated between both electrodes when the organic EL element D is controlled to emit light using dummy pixel data for temperature detection.

As shown in FIG. 20, when the voltage V _EL between the electrodes is high, the driving temperature is low, and when the voltage V _EL between the electrodes is low, the driving temperature is high. For example, when the interpolar voltage V _EL is 9.3 [V], the temperature information output unit 87 outputs temperature information indicating −10 ° C. For example, when the voltage V _EL between both electrodes is 9.3 [V], the temperature information output unit 87 outputs temperature information indicating 60 ° C.

Since the operation after the drive temperature is detected in this way is the same as that in the first embodiment, the description thereof is omitted.
As in this embodiment, by directly measuring the driving temperature of the dummy pixel circuit 71 having the same pixel structure as that of the effective display region 53, the surface temperature of the organic EL panel 51 is higher than that detected by the temperature sensor. The temperature can be detected with accuracy. As a result, the control accuracy of the cathode potential Vcathode can be improved.

(B) Case where Drive Temperature is Detected Using Pixels in Effective Display Area FIG. 21 shows a structural example of the organic EL panel 91. In the case of this embodiment, one pixel constituting the effective display area 93 is used as the temperature detection / use pixel 95.

  That is, the temperature detection combined pixel 95 is used not only for temperature detection but also for normal image display. In this specification, pixels other than the temperature detection / use pixel 95 among all the pixels constituting the effective display area 93 are referred to as normal pixels.

  In the case of FIG. 21, the temperature detection / use pixel 95 is arranged at the lower right corner in the effective display area 93. However, the number and arrangement position of the temperature detection / use pixels 95 are arbitrary. However, from the viewpoint of the influence on the display quality and the panel design, it is desirable to arrange it in one of the outer peripheral portions of the effective display area 93.

  That is, the pixel structure of the temperature detection / use pixel 95 is the same as the other pixel structures of the effective display area 93 except that a wiring for detecting the anode potential (drain potential Vd) of the organic EL element D is additionally arranged. It is. Therefore, the effective display area 93 is integrally formed by the same process.

  FIG. 22 shows main components of the organic EL display device 101 in this embodiment. In FIG. 22, the same reference numerals are given to the portions corresponding to those in FIG. 8. As shown in FIG. 22, the basic configuration is the same as the configuration described in FIG.

  22 includes an organic EL panel 91, a data line driver 15, a scanning line driver 17, a lighting period driver 19, a reset driver 21, a timing generator 25, a luminance characteristic correction unit 103, and a temperature detection unit 105. The main component.

  The luminance characteristic correction unit 103 in this embodiment also corresponds to the cathode potential determination unit 33 and the cathode potential variable unit 35 in the luminance characteristic correction unit 23 described with reference to FIG. On the other hand, the temperature detection unit 105 also corresponds to the temperature detection unit 31 in the luminance characteristic correction unit 23 described with reference to FIG.

  FIG. 23 shows a specific connection relationship between the temperature detection / use pixel 95 and the drive circuit. As shown in FIG. 23, the basic connection relationship of the temperature detection / use pixel 95 is the same as the connection relationship of the normal pixels described in FIG. Therefore, the temperature detection / use pixel 95 can be driven by the same driving method as that of the normal pixel.

Also in this case, the driving temperature of the temperature detection / use pixel 95 is realized by detecting the voltage V _EL between both electrodes appearing between both electrodes of the organic EL element D as shown in FIG. For this reason, the anode potential (drain potential Vd) and the cathode potential Vcathode of the organic EL element D are applied to the temperature detection unit 105.

  FIG. 24 illustrates an internal configuration example of the temperature detection unit 105. In the case of this embodiment, the temperature detection unit 105 includes a measurement pixel data generation unit 111, a measurement pixel data replacement unit 113, and a temperature conversion unit 115.

  The measurement pixel data generation unit 111 is a circuit device that generates measurement pixel data having a constant gradation value for temperature detection. In this embodiment, a fixed value set in advance is used for the measurement pixel data.

  In addition, the measurement pixel data generation unit 111 generates a drive temperature measurement timing signal and supplies the measurement timing signal to the measurement pixel data replacement unit 113 and the temperature conversion unit 115. The measurement timing signal is used because it is necessary to switch and supply temperature measurement pixel data and display pixel data to the temperature detection / use pixel 95.

  FIG. 25 shows an example of the measurement timing signal. In the case of FIG. 25, the measurement timing signal sets the drive temperature measurement period once every 10 seconds. In FIG. 25, the length of the temperature measurement period is emphasized, but the actual measurement period may be one frame in which light emission control is performed using pixel data for temperature measurement.

  The measurement pixel data replacement unit 113 replaces the pixel data corresponding to the temperature detection / use pixel 95 with the measurement pixel data only when the driving temperature specified by the measurement timing signal is measured, and the pixels input in other periods It is a circuit device that outputs data as it is. Of course, the insertion position of the measurement pixel data depends on the arrangement position of the temperature detection / use pixel 95.

  The temperature conversion unit 115 is a circuit device that converts a voltage detected by the temperature detection / use pixel 95 into a driving temperature during the lighting period of the organic EL element D specified by the measurement timing signal. FIG. 26 illustrates an internal configuration example of the temperature conversion unit 115. In FIG. 26, the parts corresponding to those in FIG.

As shown in FIG. 26, the basic configuration of the temperature conversion unit 105 is the same as that of the temperature conversion unit 75 described in FIG.
That is, the temperature conversion unit 105 includes a voltage follower circuit 81, an analog / digital conversion circuit (A / D conversion circuit) 83, a differential voltage calculation unit 85, and a temperature information output unit 121.

The difference is that the update of the temperature information by the temperature information output unit 121 is executed only at the specified timing notified by the measurement timing signal. Of course, the temperature information conversion process is executed based on the voltage V _EL between the electrodes of the organic EL element D detected during the lighting period based on the measurement pixel data.

  For reference, FIG. 27 shows drive signal waveforms corresponding to this embodiment. FIG. 27 is an example of a drive signal waveform used in the temperature detection / use pixel 95. Needless to say, other normal pixels are driven by the drive signal waveforms shown in FIG.

As shown in FIG. 27, between the two electrodes based on the drain potential Vd (FIG. 27 (F)) appearing in the organic EL element D during the lighting period after the temperature measurement pixel data is written and the cathode potential Vcathode in the corresponding period. The voltage V _EL will be measured.

  Since the operation after the drive temperature is determined in this manner is the same as that in the first embodiment, the description thereof is omitted. As in this embodiment, by directly measuring the driving temperature of the temperature detection / use pixel 95 arranged in the effective display area 93, the accuracy is higher than when dummy pixels are arranged outside the effective display area 93. Thus, it becomes possible to detect the driving temperature.

  This is because the temperature detection / use pixel 95 is controlled to emit light according to the display content except for the measurement timing, and thus the influence of heat generation according to the display content can be accurately detected. As a result, the control accuracy of the cathode potential Vcathode can be further improved.

(C) Case where Drive Temperature is Detected for Multiple Pixels in the Effective Display Area FIG. 28 shows a structural example of the organic EL panel 131. In the case of this embodiment, a plurality of temperature detection / use pixels 135 are dispersedly arranged in the effective display area 133. The reason why the plurality of temperature detection / use pixels 135 are arranged in a distributed manner is that the distribution of the drive temperature in the screen may not be uniform depending on the display contents and usage mode.

For example, the amount of heat generated is different between a screen area where high-luminance display continues and a screen area where low-luminance display continues, which may cause a difference in driving temperature.
For example, when the panel surface is parallel to the vertical direction, a temperature difference may occur between the upper side and the lower side of the panel surface due to the influence of thermal convection.

However, in order to detect the drive temperature for the specific temperature detection / use pixel 135 in the effective display area 133, a mechanism capable of detecting only the voltage V _EL between the electrodes at a specific position is required.
FIG. 29 shows a detailed configuration of the organic EL panel 131 in which a mechanism for this is formed. Specifically, one row selection switch element T21 is arranged for one temperature detection / use pixel 135.

Here, all the row selection switch elements T21 corresponding to the temperature detection / use pixels 135 located on the same scanning line are connected to a common control line. With this connection configuration, it is possible to read the voltage V _EL between the electrodes in units of scanning lines.

However, only by this control, a plurality of voltages V _EL between the electrodes are read out to the output terminal. Therefore, one column selection switch element T23 is arranged on each output line in which the output terminals of the row selection switch element T21 are bundled in the column direction. With this connection configuration, only one of the read bipolar voltages V _EL is read from the output terminal.

  FIG. 30 shows the main components of the organic EL display device 141 in this embodiment. 30 corresponding to those in FIG. 8 are denoted by the same reference numerals. As shown in FIG. 30, the basic configuration is the same as the configuration described in FIG.

  An organic EL display device 141 shown in FIG. 30 includes an organic EL panel 131, a data line driver 15, a scanning line driver 17, a lighting period driver 19, a reset driver 21, a timing generator 25, a luminance characteristic correction unit 143, and a temperature detection unit 145. The main component.

  The luminance characteristic correction unit 143 in this embodiment also corresponds to the cathode potential determination unit 33 and the cathode potential variable unit 35 in the luminance characteristic correction unit 23 described with reference to FIG. On the other hand, the temperature detection unit 145 also corresponds to the temperature detection unit 31 in the luminance characteristic correction unit 23 described with reference to FIG.

  FIG. 31 shows a specific connection relationship between the temperature detection / use pixel 135 and the drive circuit. As shown in FIG. 31, the basic connection relationship of the temperature detection / use pixel 135 is the same as the connection relationship of the normal pixels described in FIG. Therefore, the temperature detection / use pixel 135 can be driven by the same driving method as that of the normal pixel.

However, as described above, the anode electrode of the organic EL element D constituting the temperature detection / use pixel 135 and the temperature detection unit 145 are connected through the row selection switch element T21 and the column selection switch element T23. Therefore, the process of providing the pixel data for measurement to the temperature detection / use pixel 135 that is the object of measurement and the selection operation of the interpolar voltage V _EL appearing during the light emission period are different from those of the other embodiments.

  FIG. 32 shows an example of the internal configuration of the temperature detector 145 used in this embodiment. In the case of this embodiment, the temperature detection unit 145 includes a measurement pixel data generation unit 151, a measurement target pixel specification unit 153, a measurement pixel data replacement unit 155, and a temperature conversion unit 157.

  The measurement pixel data generation unit 151 is a circuit device that generates measurement pixel data having a constant gradation value for temperature detection. In this embodiment, a fixed value set in advance is used for the measurement pixel data.

  In addition, the measurement pixel data generation unit 151 generates a drive temperature measurement timing signal and supplies the measurement timing signal to the measurement target pixel specification unit 153, the measurement pixel data replacement unit 155, and the temperature conversion unit 157.

  The measurement timing signal is used because it is necessary to switch and supply temperature measurement pixel data and display pixel data to the temperature detection / use pixel 135. As the measurement timing signal, for example, the signal described with reference to FIG. 25 is used.

  The measurement target pixel designating unit 153 is a circuit device that generates a signal designating a specific temperature detection / use pixel 135 based on the measurement timing signal. Here, the measurement target pixel specifying unit 153 outputs the pixel position as a measurement position signal.

  The measurement pixel data replacement unit 155 replaces the pixel data corresponding to the temperature detection combined pixel 135 specified by the measurement position signal with the measurement pixel data only when measuring the driving temperature specified by the measurement timing signal, In this period, the circuit device outputs the input pixel data as it is.

  The temperature conversion unit 157 is a circuit device that converts a voltage detected by the temperature detection / use pixel 135 into a driving temperature during the lighting period of the organic EL element D specified by the measurement timing signal. FIG. 33 shows an internal configuration example of the temperature conversion unit 157. In FIG. 33, parts corresponding to those in FIG.

As shown in FIG. 33, the basic configuration of the temperature conversion unit 157 is the same as that of the temperature conversion unit 75 described in FIG.
That is, the temperature conversion unit 157 includes a voltage follower circuit 81, an analog / digital conversion circuit (A / D conversion circuit) 83, a differential voltage calculation unit 85, and a temperature information output unit 161.

  The difference is that the update of the temperature information by the temperature information output unit 161 is executed only at the specified timing notified by the measurement timing signal. In the case of the temperature information detection unit 161, the temperature information is output with measurement position information added thereto. Thereby, the luminance characteristic correcting unit 143 can switch the cathode potential Vcathode for each region.

However, the luminance characteristic correction unit 143 can generate a single cathode potential Vcathode in consideration of the temperature distribution in the panel surface.
For reference, FIG. 34 shows drive signal waveforms corresponding to this embodiment. FIG. 34 shows an example of a drive signal waveform used in the temperature detection / use pixel 135. Needless to say, the other normal pixels are driven by the driving signals shown in FIG.

The drive waveform shown in FIG. 34 is basically the same as the waveform described in FIG. However, the drain potential Vd (FIG. 34 (F)) appearing in the organic EL element D and the cathode potential in the corresponding period during the period when one of the plurality of temperature detection / use pixels 135 is selected (FIG. 34 (H)). The voltage V _EL between the electrodes is measured based on Vcathode.

  Since the operation after the drive temperature is determined in this manner is the same as that in the first embodiment, the description thereof is omitted. As in this embodiment, by directly measuring the driving temperature of the plurality of temperature detection / use pixels 135 arranged in the effective display area 133, not only the driving temperature of the effective display area 133 can be accurately measured, but also in-plane The temperature distribution of can also be detected.

In particular, in the case of portable electronic devices, they are easily affected by the usage environment such as direct sunlight and temperature changes, and there are various usage modes. Therefore, a more accurate cathode can be detected by detecting the temperature distribution in the panel surface. The potential Vcathode can be controlled.
Further, when the effective display area is large (wide), temperature unevenness is likely to occur within the panel surface, and therefore, the cathode potential Vcathode can be controlled more accurately by combining the above-described mechanisms.

(C) Other Embodiments (C-1) Other Driving Temperature Examples In the above-described Embodiment 1, the case where the surface temperature of the organic EL panel 13 detected using the temperature sensor is used as the driving temperature has been described. . In the second embodiment, the case where the temperature measured from the voltage V _EL between both electrodes of the organic EL element is used as the driving temperature has been described.

  However, the driving temperature may be the ambient temperature (air temperature) around the EL panel. Also, temperature information given from the outside may be used.

(C-2) Product example (a) Drive IC
The above-described organic EL display devices (organic EL panel module and drive condition control unit) can be formed on a single panel, but the processing circuit portion and the pixel matrix can be separately manufactured and distributed. it can.

For example, the driver IC block and the drive condition control unit are independent drive ICs (integrated
circuit) and can be distributed independently from the organic EL panel. Of course, one driver IC can be constituted by the driver IC block and the drive condition control unit.

(B) Display Module The organic EL display device in the above-described embodiment can be distributed in the form of a display module 171 having the appearance configuration shown in FIG.
The display module 171 has a structure in which a facing portion 173 is bonded to the surface of the support substrate 175. The facing portion 173 uses a glass or other transparent member as a base material, and a color filter, a protective film, a light shielding film, and the like are disposed on the surface thereof.

  Note that the display module 171 may be provided with an FPC (flexible printed circuit) 177 and the like for inputting and outputting signals and the like to the support substrate 175 from the outside.

(C) Electronic device The organic EL display device in the embodiment described above is also distributed in a product form mounted on an electronic device.
FIG. 36 illustrates a conceptual configuration example of the electronic device 181. The electronic device 181 includes the organic EL display device 183 and the system control unit 185 described above. The processing content executed by the system control unit 185 differs depending on the product form of the electronic device 181.

Note that the electronic device 181 is not limited to a device in a specific field as long as it has a function of displaying an image or video generated in the device or input from the outside.
For example, a television receiver is assumed as this type of electronic apparatus 181. FIG. 37 shows an appearance example of the television receiver 191.

  A display screen 197 composed of a front panel 193, a filter glass 195, and the like is disposed on the front surface of the television receiver 191. The portion of the display screen 197 corresponds to the organic EL display device described in the embodiment.

  Further, for example, a digital camera is assumed as this type of electronic device 181. FIG. 38 shows an appearance example of the digital camera 201. FIG. 38A shows an example of the appearance on the front side (subject side), and FIG. 38B shows an example of the appearance on the back side (photographer side).

  The digital camera 201 includes an imaging lens (FIG. 38 shows the state in which the protective cover 203 is closed, so that it is disposed on the back side of the protective cover 203), a flash light emitting unit 205, a display screen 207, a control switch 209, and a shutter. It consists of buttons 211. Among these, the display screen 207 corresponds to the organic EL display device described in the embodiment.

For example, a video camera is assumed as this type of electronic device 181. FIG. 39 shows an appearance example of the video camera 221.
The video camera 221 includes an imaging lens 225 that images a subject in front of the main body 223, a shooting start / stop switch 227, and a display screen 229. Among these, the portion of the display screen 229 corresponds to the organic EL display device described in the embodiment.

  Further, for example, a portable terminal device is assumed as this type of electronic apparatus 181. FIG. 40 shows an example of the appearance of a mobile phone 231 as a mobile terminal device. A cellular phone 231 illustrated in FIG. 40 is a foldable type, and FIG. 40A illustrates an appearance example in a state where the housing is opened, and FIG. 40B illustrates an appearance example in a state where the housing is folded.

  The cellular phone 231 includes an upper housing 233, a lower housing 235, a connecting portion (in this example, a hinge portion) 237, a display screen 239, an auxiliary display screen 241, a picture light 243, and an imaging lens 245. Among these, the display screen 239 and the auxiliary display screen 241 correspond to the organic EL display device described in the embodiment.

In addition, for example, a computer is assumed as this type of electronic device 181. FIG. 41 shows an example of the appearance of a notebook computer 251.
The notebook computer 251 includes a lower casing 253, an upper casing 255, a keyboard 257, and a display screen 259. Among these, the display screen 259 corresponds to the organic EL display device described in the embodiment.

  In addition to these, the electronic device 181 may be an audio playback device, a game machine, an electronic book, an electronic dictionary, or the like.

(C-3) Other Display Device Examples In the description of the embodiments, the case where the luminance characteristic correction function is mounted on the organic EL display device has been described.

  However, the luminance characteristic correction function can also be applied to other self-luminous display devices. For example, the present invention can be applied to an inorganic EL display device, a display device in which LEDs are arranged, and other display devices in which light emitting elements having a diode structure are arranged on a screen.

(C-4) Control Device Configuration In the above description, the case where the luminance characteristic correction unit is realized in hardware has been described.
However, part or all of the luminance characteristic correction unit can be realized as software processing.

(C-5) Others Various modifications can be considered for the above-described embodiments within the scope of the gist of the invention. Various modifications and applications created or combined based on the description of the present specification are also conceivable.

It is a figure which shows the structural example of a pixel circuit. It is a figure explaining the source potential fluctuation | variation of the current drive element by a drive temperature characteristic (conventional example). It is a figure explaining the temperature change of the voltage between both poles which generate | occur | produces between the both electrodes of an organic EL element. It is a figure explaining the temperature dependence characteristic of light emission luminance. It is a figure explaining the drive temperature characteristic of the voltage between both poles which generate | occur | produces between the both electrodes of an organic EL element. It is a figure explaining the control method of the cathode potential of an organic EL element (proposed method). It is a figure explaining the application effect of a proposal technique. It is a figure which shows the function structural example of the organic electroluminescent display apparatus which concerns on the example 1 of a form. It is a figure which shows the connection relation of a pixel circuit and a drive circuit. It is a figure which shows the internal structural example of a brightness | luminance characteristic correction | amendment part. It is a figure which shows the example of a table referred for the temperature characteristic correction | amendment of a luminance characteristic. It is a figure which shows the internal structural example of a cathode potential variable part. It is a figure which shows the correspondence of a drive signal waveform and the terminal potential of a current drive element. It is a figure explaining the drive temperature characteristic of a source potential. It is a figure which shows the structural example of the organic electroluminescent panel used in the example 2 of a form (the 1). It is a figure which shows the function structural example of the organic electroluminescent display apparatus which concerns on the example 2 of a form (the 1). It is a figure which shows the connection relation of a pixel circuit and a drive circuit. It is a figure which shows the internal structural example of a temperature detection part. It is a figure which shows the internal structural example of a temperature conversion part. It is a figure which shows the example of the reference table which recorded the corresponding relationship of detection voltage and drive temperature. It is a figure which shows the structural example of the organic electroluminescent panel used in the example 2 (the 2). It is a figure which shows the function structural example of the organic electroluminescent display apparatus which concerns on the example 2 of a form (the 2). It is a figure which shows the connection relation of a pixel circuit and a drive circuit. It is a figure which shows the internal structural example of a temperature detection part. It is a figure which shows an example of a measurement timing signal. It is a figure which shows the internal structural example of a temperature conversion part. It is a figure which shows the correspondence of a drive signal waveform and the terminal potential of a current drive element. It is a figure which shows the structural example of the organic electroluminescent panel used in the example 2 (the 3). It is a figure explaining the detailed structure of an organic electroluminescent panel. It is a figure which shows the function structural example of the organic electroluminescent display apparatus which concerns on the example 2 of a form (the 3). It is a figure which shows the connection relation of a pixel circuit and a drive circuit. It is a figure which shows the internal structural example of a temperature detection part. It is a figure which shows the internal structural example of a temperature conversion part. It is a figure which shows the correspondence of a drive signal waveform and the terminal potential of a current drive element. It is a figure which shows the structural example of a display module. It is a figure which shows the function structural example of an electronic device. It is a figure which shows the example of goods of an electronic device. It is a figure which shows the example of goods of an electronic device. It is a figure which shows the example of goods of an electronic device. It is a figure which shows the example of goods of an electronic device. It is a figure which shows the example of goods of an electronic device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Organic EL display apparatus 23 Luminance characteristic correction | amendment part 31 Temperature detection part 33 Cathode potential determination part 35 Cathode potential variable part 55 Dummy pixel area | region 63 Luminance characteristic correction | amendment part 71 Dummy pixel data generation part 73 Dummy pixel insertion part 75 Temperature conversion part 95 Temperature Detection-use pixel 103 Luminance characteristic correction unit 111 Measurement pixel data generation unit 113 Measurement pixel data replacement unit 115 Temperature conversion unit 135 Temperature detection-use pixel 143 Luminance characteristic correction unit 151 Measurement pixel data generation unit 153 Measurement target pixel designation unit 155 Pixel data replacement unit for measurement 157 Temperature conversion unit

Claims (10)

A pixel having an EL (Electro Luminescence) element, a current driving element that drives the EL element in current, and a storage circuit that stores charges corresponding to pixel data between a control terminal and a current output terminal of the current driving element A luminance characteristic correction apparatus for correcting luminance characteristics of an EL panel in which circuits are arranged in a matrix,
If the pixel data is the same, the EL element according to the current value of the drive temperature so that the potential change during the lighting period appearing at the current output terminal is constant regardless of the change in the drive temperature of the EL element. A cathode potential determination unit for determining a cathode potential value to be applied to the cathode terminal of
And a cathode potential variable unit that applies a cathode potential corresponding to the cathode potential value to a cathode terminal of the EL element. The luminance characteristic correction apparatus according to claim 1,
The light emitting layer of the said EL element is comprised with an organic compound. The brightness | luminance characteristic correction apparatus characterized by the above-mentioned. The luminance characteristic correction apparatus according to claim 1,
The drive characteristic is an ambient temperature around the EL panel. The luminance characteristic correction apparatus according to claim 1,
The drive characteristic is a temperature detected by a temperature detector disposed on or near the surface of the EL panel. The luminance characteristic correction apparatus according to claim 1,
The drive characteristic is a temperature detected through a potential appearing at the current output terminal. The luminance characteristic correction apparatus according to claim 1,
The panel temperature is a temperature detected through a potential appearing at the current output terminal of a pixel circuit arranged outside an effective display area. A pixel having an EL (Electro Luminescence) element, a current driving element that drives the EL element in current, and a storage circuit that stores charges corresponding to pixel data between a control terminal and a current output terminal of the current driving element An EL panel in which circuits are arranged in a matrix;
A panel drive unit for controlling writing of pixel data to each pixel circuit and light emission operation;
If the pixel data is the same, the EL element according to the current value of the drive temperature so that the potential change during the lighting period appearing at the current output terminal is constant regardless of the change in the drive temperature of the EL element. A cathode potential determination unit for determining a cathode potential value to be applied to the cathode terminal of
An EL display device, comprising: a cathode potential variable portion that applies a cathode potential corresponding to the cathode potential value to a cathode terminal of the EL element. A pixel having an EL (Electro Luminescence) element, a current driving element that drives the EL element in current, and a storage circuit that stores charges corresponding to pixel data between a control terminal and a current output terminal of the current driving element An EL panel in which circuits are arranged in a matrix;
A panel drive unit for controlling writing of pixel data to each pixel circuit and light emission operation;
If the pixel data is the same, the EL element according to the current value of the drive temperature so that the potential change during the lighting period appearing at the current output terminal is constant regardless of the change in the drive temperature of the EL element. A cathode potential determination unit for determining a cathode potential value to be applied to the cathode terminal of
An electronic apparatus comprising: a cathode potential variable unit that applies a cathode potential corresponding to the cathode potential value to a cathode terminal of the EL element; and a system control unit. A pixel having an EL (Electro Luminescence) element, a current driving element that drives the EL element in current, and a storage circuit that stores charges corresponding to pixel data between a control terminal and a current output terminal of the current driving element A luminance characteristic correction method for correcting the luminance characteristics of an EL panel in which circuits are arranged in a matrix,
A process of acquiring a current value of the driving temperature of the EL element;
If the pixel data is the same, the EL element according to the current value of the drive temperature so that the potential change during the lighting period appearing at the current output terminal is constant regardless of the change in the drive temperature of the EL element. And a process of determining a cathode potential value to be applied to the cathode terminal. A pixel having an EL (Electro Luminescence) element, a current driving element that drives the EL element in current, and a storage circuit that stores charges corresponding to pixel data between a control terminal and a current output terminal of the current driving element In a computer for correcting the luminance characteristics of an EL panel in which circuits are arranged in a matrix,
A process of acquiring a current value of the driving temperature of the EL element;
If the pixel data is the same, the EL element according to the current value of the drive temperature so that the potential change during the lighting period appearing at the current output terminal is constant regardless of the change in the drive temperature of the EL element. And a process for determining a cathode potential value to be applied to the cathode terminal of the computer program.

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