Abstract: A display device includes a display panel on which a plurality of sub-pixels are disposed; a timing controller configured to transmit an image control signal to a host system to receive image data from the host system; a data driving circuit configured to convert the image data transmitted from the timing controller into a data voltage and configured to supply the data voltage to the display panel; and a semi-off switching circuit configured to control the image control signal so that the image data is cut off from the host system during a semi-off period of a predetermined time from a time when an off monitoring signal is transmitted from the host system in response to the power off signal.

Abstract: A pixel driving circuit includes a data writing sub-circuit, a driving sub-circuit, and a control sub-circuit. The data writing sub-circuit is configured to: in response to a first scanning signal and a third scanning signal, write a first data signal into the driving sub-circuit; and in response to a second scanning signal and the third scanning signal, write a second data signal into the driving sub-circuit. The control sub-circuit is configured to, in response to an enable signal, connect a driving transistor to a first power supply voltage signal terminal and an element to be driven. The driving sub-circuit is configured to: according to the first data signal and a first power supply voltage signal, output a driving signal; and according to the second data signal and the first power supply voltage signal, control an operating state of the element to be driven.

Abstract: The preset disclosure relates to a pixel driving circuit, a pixel driving method, an array substrate and a display device. The pixel driving circuit includes a pixel driving unit and an optical detection unit. The pixel driving unit is configured to drive a light-emitting element included in a pixel unit to emit light. The optical detection unit includes a photoelectric conversion sub-circuit and a switch control sub-circuit. The photoelectric conversion sub-circuit is configured to receive light emitted from the light-emitting element, and convert the light into an electrical signal. The switch control sub-circuit is configured to output the electrical signal under control of a first scanning signal. The pixel driving unit is configured to adjust brightness of the light emitted from the light-emitting element according to the electrical signal.

Abstract: Provided is a pixel including an organic light emitting diode, a driving circuit, and a light receiving circuit. The driving circuit is configured to supply a driving current corresponding to a data signal supplied through a data line during a scan period to the organic light emitting diode during an emission period, and to supply a first sensing current corresponding to threshold voltage/mobility information of a driving transistor or degradation information of the organic light emitting diode to a feedback line during a current sensing period. The light receiving circuit is configured to supply a second sensing current corresponding to luminance of the organic light emitting diode to the feedback line during the emission period.

Abstract: The present invention provides an organic light emitting diode pixel circuit, a driving method thereof and a display panel. The OLED pixel circuit comprises a light emitting module comprising an organic light emitting diode for emitting light; a light emitting control module for controlling the light emitting module to emit light; a driving module, so as to control the light emitting module to emit light; a threshold compensation module, and a data signal input module configured for inputting a data signal; the OLED pixel circuit further comprises: a touch sensing module configured for generating a touch sensing signal; and a touch detection module configured for detecting the touch sensing signal, and providing an initial voltage for the threshold compensation module, wherein the driving module amplifies the touch sensing signal generated by the touch sensing module and then outputs it to the touch detection module.

Abstract: A circuit and method of driving a display panel requiring gray scale control wherein the voltage applied to a row of pixels is equal to the sum of voltages of opposite sign with respect to ground applied respectively to the row electrode and column electrodes whose intersection with the row defines the pixels. Gray scale is realized through modulation of the voltage applied to the column electrodes. Typically for video application, 256 individual gray levels are required corresponding to luminance levels ranging from zero (no emissive luminance) to full luminance. The required luminance for each gray level is not a linear function of the gray level number but rather corresponds to an approximate quadratic function of this number. The present invention facilitates generation of luminance values for each gray level that approximates this functional dependence (i.e. Gamma corrected) with a non-linear voltage ramp terminated by a digital clock having 256 (8 bit) resolution.

Abstract: A display device for displaying a predetermined color during an interval. The display device includes a plurality of pixels, each said pixel having at least two light emitting elements. Each light emitting element emits a corresponding color within the interval. Some of the light emitting elements of two adjacent said pixels are grouped into a first light emitting element group and the remaining light emitting elements of the two adjacent said pixels are grouped into a second light emitting element group. The first light emitting element group and the second light emitting element group are time-divisionally driven, one of the first and second light emitting element groups being driven within a given period, thereby displaying the predetermined color within the interval. The interval is one frame, and the one frame is divided into two subframes. The first and second light emitting element groups are time-sharingly driven.

Abstract: Disclosed are an organic light emitting display device and a display panel thereof, which are capable of performing a recovery driving for recovering a threshold voltage of a driving transistor to be within a range of compensation for the threshold voltage if the threshold voltage of the driving transistor deviates from the range of the compensation for the threshold voltage as a driving time of the driving transistor of a pixel increases.

Abstract: Disclosed herein is a display apparatus, including: a pixel array section including a plurality of pixels, a writing transistor, a driving transistor, a first switching transistor, a holding capacitor, and a second switching transistor; a first scanning section configured to drive the writing transistor in a unit of a row of the pixels; a second scanning section configured to drive the switching transistors in synchronism with scanning by the first scanning section; and a third scanning section configured to control the second switching transistors to a non-conducting state within a period after the image signal is written by the writing transistor until the signal writing period of the same row of the pixels ends but to a conducting state within any other period.

Abstract: A display device having subpixel repeating groups is presented. Each subpixel repeating group has an even number of four or more subpixels and includes odd-numbered subpixels and even-numbered subpixels alternately arranged in a row direction, each subpixel having a color. A data driver is configured to provide data signals to the subpixels such that the odd-numbered subpixels have a polarity that is opposite that of the even-numbered subpixels in each of the subpixel repeating groups. A first subpixel repeating group and a second subpixel repeating group are adjacent in the row direction. The first subpixel of the first subpixel repeating group and the first subpixel of the second subpixel repeating group have the same color and opposite polarities.

Abstract: Discussed are a display device and a method for controlling the same, which are capable of achieving a reduction in power consumption, through selective application of a charge share mode or a pre-charge mode in accordance with the swing width of a data voltage. The disclosed method includes the steps of determining a positive or negative polarity of input image data on the basis of reference data and outputting a pre-charge enable signal when two successive image data have the same polarity; supplying a pre-charge voltage to a corresponding output channel in response to the pre-enable signal; and converting the image data into a data voltage, supplying the converted data voltage to a corresponding data line through the corresponding output channel.

Abstract: The invention provides an image display device capable of reducing the transmission delay of a scanning signal. A plurality of scanning signal lines are wired in one pixel circuit row. Pixel circuits of the pixel circuit row are connected to any of the plurality of scanning signal lines.

Abstract: An organic light emitting diode (OLED) display device includes a plurality of OLED pixels. In one aspect, each pixel respectively includes a first capacitor connected between a data line and a first node, a switching transistor connecting the first node and a second node, a second capacitor connected between the second node and a third node, a driving transistor having a gate electrode connected to the third node and controlling a driving current flowing from a first power source voltage to an OLED, and a reference voltage transistor transmitting a reference voltage to the first node.

Abstract: A pixel circuit has a light emitting element and a driver electrically connected to the light emitting element. A reverse bias voltage is applied to the driver to reduce a shift amount of a threshold voltage of the driver.

Abstract: A display apparatus disclosed herein includes a plurality of pixel circuits, each having a plurality of switches configured to receive a driving signal of a predetermined period and to be controlled for opening and closing operation by the driving signal, a drive circuit configured to control the open/closed state of the switches, being operable to scan the pixel circuits and open and close the switches in periods independent of each other.

Abstract: An emission control circuit for controlling emission of R, G, B EL elements and method for driving an organic light emitting diode display using the same. An emission control signal generating circuit of a flat panel display includes a plurality of pixels. Each pixel includes a plurality of EL elements, and emission of the elements is controlled by emission control signals. The circuit includes a first signal generating device for generating one of the emission control signals, and a plurality of second signal generating devices for generating other ones of the emission control signals using an output signal of the first signal generating device and an external control signal. The first signal generating device may include a shift register. Each of the plurality of second signal generating devices may include a NAND gate using the external signal and the external control signal, or an inverted signal thereof, as two inputs.

Abstract: A gate of a driving transistor is set to a offset level corresponding to the threshold of the driving transistor by an initializing current flowing between a source and a drain of the driving transistor or a compensating transistor for the driving transistor. A conduction state of the driving transistor is set according to a gate voltage of the gate of the driving transistor that corresponds to a data signal and the threshold of the driving transistor. A current of which a level corresponds to the conduction state and of which the direction is opposite to the direction of the initializing current flows through driving transistor.

Abstract: Method, apparatus and systems for driving electroluminescent segments in electroluminescent displays are disclosed. Each segment in the display receives a series of first pulses alternating in polarity at a first electrode and a series of second pulses at a second electrode. Each of the second pulses corresponds to one of the first pulses and is opposite in polarity. The width of the second pulses corresponds to the parasitic resistance of the segment.

Abstract: A light-emitting device includes a drive transistor that controls a current to be supplied to a light-emitting element from a power supply line, an element continuity portion that electrically connects the drive transistor with the light-emitting element, an initializing transistor that is turned ON to diode-connect the drive transistor, and a connecting portion that electrically connects the drive transistor with the initializing transistor. The power supply line includes a first portion extending in a predetermined direction. The element continuity portion and the connecting portion are formed from the same layer as that of the power supply line and are located on one side along the width of the first portion across the drive transistor.

Abstract: A light-emitting device includes a drive transistor that controls a current to be supplied to a light-emitting element from a power supply line, an electrical continuity portion that electrically connects the drive transistor with the light-emitting element, an initializing transistor that is turned ON to diode-connect the drive transistor, and a connecting portion that electrically connects the drive transistor with the initializing transistor. The power supply line including a first portion extending in a first direction and a second portion extending in a second direction that crosses the first direction. The connecting portion being positioned in an area between the first and second power supply lines in plan view.

Abstract: An organic light emitting display includes a display panel including data lines, gate lines crossing the data lines, and pixels and a panel driving circuit which supplies a data voltage to the pixels of the display panel during a power-on period and then is additionally driven for a predetermined power-on delay duration time delayed from a power-off start time of a power input signal. The panel driving circuit supplies a reverse polarity recovery voltage having a polarity opposite the data voltage to the pixels or supplies a recovery voltage, which is different from a gate voltage of a driving element of each of the pixels, to a source terminal of the driving element of each pixel for the predetermined power-on delay duration time.

Abstract: The present invention relates to a front light system which can be built with thin film light emitting diodes (LEDs), such as organic light emitting diodes (OLEDs) or electro-luminescent light emitting diodes. The front light system may be built on a thin and flexible substrate and can generate lighting of satisfactory uniformity and with high efficiency. The system also can potentially be inexpensive. The front light system of the present invention is particularly suitable for keymat applications wherein a flexible reflective display on top of a touch sensitive surface or device, is used as an output device.

Abstract: The data driver of a flat panel display includes: an output driver configured to output a plurality of amplified data signals for a plurality of channels corresponding to a plurality of data lines, the plurality of channels including: a plurality of amplifiers configured to amplify a plurality of input data signals and to supply the amplified data signals to the data lines; and a plurality of chopping controllers, each of the chopping controllers being coupled connected to a plurality of input terminals of a corresponding amplifier of the amplifiers and configured to receive a first control signal or a second control signal to periodically change signals applied to positive and negative input terminals from among the input terminals of the amplifiers.

Abstract: A display device, includes: a plurality of thin film transistors which comprise a gate electrode, a source electrode and a drain electrode; a plurality of pixel electrodes which are respectively connected to the drain electrode of the thin film transistors; a plurality of gate lines which are respectively disposed to the opposite edge parts of the pixel electrodes in a lengthwise direction of the pixel electrodes, and connected to the gate electrode of the thin film transistors; and a plurality of data lines which are respectively disposed to a single edge part of the pixel electrodes in a widthwise direction of the pixel electrodes, and connected to the source electrode of the thin film transistors, a pair of pixel electrodes adjoining each other to interpose the single data line therebetween, and a pair of thin film transistors which are respectively connected to the pair of pixel electrodes being connected with the same single data line.

Abstract: Disclosed is an electrophoretic display and a method for driving the electrophoretic display. The method for driving the electrophoretic display, which includes a first electrode, a second electrode, and an electrophoretic layer including electrophoretic particles disposed in a plurality of pixels receiving the voltage for driving from the first electrode and the second electrode and provided between the first electrode and the second electrode includes applying a reset voltage to the pixels, applying a reset compensation voltage including reversed polarity to the reset voltage to the pixels, applying an image display voltage including the same or different polarity during a predetermined time between the neighboring pixels, and applying an image display compensation voltage including reversed polarity to the image display voltage to the pixels during a predetermined time.

Abstract: A driving method of a liquid crystal display panel having a source line and a counter electrode, includes driving the counter electrode to a first potential, driving the, counter electrode to a second potential being different from the first potential, setting the counter electrode and the source line to a third potential by short-circuiting the counter electrode and the source line to an interconnection having a potential between the first potential and the second potential, and driving the source line to a potential corresponding to an image data. The setting of the counter electrode and the source line to the third potential occurs in a period of one frame.

Abstract: A flat panel display includes a flexible substrate; a passive matrix display having an array of pixels formed on a side of the flexible substrate, and row and column electrodes formed on the same side of the flexible substrate and connected to the pixels for providing data and selection signals to the pixel elements; a plurality of electrical contacts formed on the same side of the substrate and electrically connected to the row and column electrodes; and discrete data and selection drivers located on the same side of the flexible substrate around the periphery of the passive matrix display and electrically connected to the electrical contacts for driving the pixels of the passive matrix display.

Abstract: A data driver capable of displaying images with a substantially uniform brightness, an organic light emitting display device using the same, and a method of driving the organic light emitting display device. The data driver includes a plurality of current sink units for controlling predetermined currents to flow through data lines, a plurality of voltage generators for resetting values of gray scale voltages using compensation voltages generated when the predetermined currents flow, a plurality of digital-to-analog converters for selecting one gray scale voltage among the gray scale voltages as a data signal in response to bit values of the data supplied from the outside, and a plurality of switching units for supplying the data signal to the data lines. The predetermined currents may be set equal to pixel currents that correspond to a maximum brightness.

Abstract: In one embodiment of the present invention, a liquid crystal display device according to the present invention includes a plurality of pixels, each including first and second subpixels. When a predetermined grayscale tone is displayed continuously through four or more consecutive even number of vertical scanning periods, the first and second subpixels have different luminances in at least two of the even number of vertical scanning periods, first polarity periods that are included in the vertical scanning periods and that maintain a first polarity are as long as second polarity periods that are also included in the vertical scanning periods and that maintain a second polarity for each of the first and second subpixels, and in each of the first and second polarity periods, the difference between the average of effective voltages applied to the liquid crystal layer of the first subpixel and that of effective voltages applied to the liquid crystal layer of the second subpixel is substantially equal to zero.

Abstract: A pixel circuit and an organic light-emitting diode (OLED) display using the pixel circuit is provided. The pixel circuit includes: an OLED; a third N-channel metal-oxide semiconductor (NMOS) transistor coupled to a data line and a first scan line and configured to apply a data signal to a first node; a storage capacitor having one terminal coupled to the first node and the other terminal coupled to a second node; a fourth NMOS transistor coupled between a first power and the second node and configured to apply a voltage of the first power to the second node; a first NMOS transistor having a first electrode, a second electrode, and a gate electrode coupled to the second node; and a second NMOS transistor coupled between the second node and the first electrode of the first NMOS transistor and configured to diode-connect the first NMOS transistor.

Abstract: A display apparatus including a plurality of data lines which transmit a data signal received from a data driving unit, a plurality of first gate lines and a plurality of second gate lines, which cross the data lines and are arranged in such a manner that the first gate lines and the second gate lines alternate with each other, a plurality of pixels which are defined by the data lines, the first gate lines, and the second gate lines, each of the pixels including a first sub-pixel electrode to which a first data voltage is applied by a first switching device connected to one of the first gate lines and a second sub-pixel electrode to which a second data voltage is applied by a second switching device connected to one of the second gate lines, and a gate driving unit which selects a scanning group including two or more first gate lines and two or more second gate lines, applies a gate-on voltage to the first gate lines of the scanning group according to a first predetermined scanning order, and applies the gate

Abstract: A drive circuit which outputs an output signal to an output terminal, includes a drive transistor configured to output a gradation current to the output terminal; a single differential amplifier; a resistance element connected with the drive transistor; and a plurality of switches. The plurality of switches are controlled such that a precharge voltage is outputted from the differential amplifier to the output terminal in a first period while blocking off an output from the drive transistor and such that a gradation current is outputted from the drive transistor to the output terminal in a second period after the first period.

Abstract: A display apparatus employs a pixel array section including pixel circuits forming a matrix, signal lines as columns, scan lines as rows and power-supply lines, and driving sections. The driving sections are a signal selector, a write scanner and a drive scanner. The signal selector provides an electric potential representing a gradation or a predetermined reference electric potential. The write scanner provides a control signal. The drive scanner provides a power-supply voltage changing the electric potential from high to low. The drive scanner drives adjacent power-supply lines as a group. The number of lines as a group is determined in advance. The drive scanner switches a power-supply voltage from high to low and vice versa, and applies the voltage to groups by shifting the phase from group to group. The voltage is supplied to a group at the same phase and switched the electric potential.

Abstract: To provide a display device including a flexible panel that can be handled without seriously damaging a driver circuit or a connecting portion between circuits. The display device includes a bent portion obtained by bending an element substrate. A circuit for driving the display device is provided in the bent portion and a wiring extends from the circuit, whereby the strength of a portion including the circuit for driving the display device is increased and failure of the circuit is reduced. Furthermore, the element substrate is bent in a connecting portion between an external terminal electrode and an external connecting wiring (FPC) so that the element substrate provided with the external terminal electrode fits the external connecting wiring, whereby the strength of the connecting portion is increased.

Abstract: An organic light emitting diode (OLED) display and an operating method thereof are provided. The organic light emitting diode display includes an organic light emitting diode display panel and a driving circuit. The organic light emitting diode display panel has a plurality of pixels. The driving circuit is coupled to the organic light emitting display panel and receives a primitive display frame. The driving circuit generates a first frame and a second frame corresponding to the primitive display frame by a polarity inverting means, and outputs a zero gray-level pixel voltage to the corresponding pixels of the organic light emitting diode display panel corresponding to a negative polarity data of the first frame and the second frame, wherein the second frame is adjacent to the first frame.

Abstract: A liquid crystal display device with no flicker and with bright excellent display is provided. A polarity pattern of a conventional frame inversion driving is one kind of display. A polarity pattern of a conventional source line inversion driving is two kinds of display, and a disclination pattern is one kind of display. On the contrary, in a circuit structure of the present invention, polarity patterns are made to have not less than four kinds, and disclination patterns are made to have not less than two kinds. By this, bright display in which flicker is not included and poor display due to disclination is improved, can be obtained.

Abstract: The display device includes an output circuit, a threshold control circuit which sequentially selects one of a forward bias voltage and a reverse bias voltage, and a power supply control circuit which applies one of the forward bias voltage and the reverse bias voltage which is selected to a gate of a transistor included in the output circuit. Time in which the reverse bias voltage is applied to the gate of the transistor is determined in accordance with time in which the forward bias voltage is applied to the gate of the transistor.

Abstract: Disclosed are a direct current converter and an organic light emitting display including the converter. The converter includes a power supply generating an input power, a first power generator receiving the input power and a selected voltage from a selector and generating a first voltage, a first output terminal connected to the first power generator and outputting the first voltage; a second power generator receiving the input power and generating a second voltage, a second output terminal connected to the second power generator and outputting the second voltage, an external feedback wiring providing a feedback voltage, a feedback terminal connected to the external feedback wiring and inputting the feedback voltage to the selector, and the selector connected to and transferring the selected voltage to the first power generator, where the selected voltage is one of the feedback voltage and the voltage output from the first output terminal.

Abstract: Charge balanced display data writing systems, apparatuses, and methods use write and hold cycles of opposite polarity during selected frame update periods. A release cycle may be provided to reduce the chance that a given display element will become stuck in an actuated state.

Abstract: A display device, including a substrate; an array of pixels arranged in rows and columns forming a light-emitting area over the substrate, each pixel including a first electrode, one or more layers of light-emitting material located over the first electrode, and a second electrode located over the one or more layers of light-emitting material; a first serial buss having a plurality of electrical conductors, each electrical conductor connecting one chiplet in a first set of chiplets to only one other chiplet in the first set in a serial connection, the chiplets being distributed over the substrate in the light-emitting area, each chiplet including one or more store-and-forward circuits for storing and transferring data connected to its corresponding electrical conductor; and a driver circuit in each chiplet for driving at least one pixel in response to data stored in the store-and-forward circuit.

Abstract: A common power line shared by all the pixels allows threshold correction to be performed simultaneously on all the pixels. Video signal lines are set to a second reference potential higher than a reference potential, followed by multi-step threshold correction and video signal writing which are performed in a line sequential manner. Performing the threshold correction immediately before the video signal writing ensures shorter time from the threshold correction to the video signal writing. This suppresses leak currents, providing improved image quality.

Abstract: Methods for displaying an image on a color display having a target display white point luminance and chromaticity, and including three gamut-defining emitters defining a display gamut and two or more additional emitters which emit light within the display gamut; the method including receiving a three-component input image signal; transforming the three-component input image signal to a five-or-more component drive signal; and providing the drive signal to display an image corresponding to the input image signal. One method provides a reproduced luminance value higher than the sum of the respective luminance values of the three components of the input signal when reproduced with the gamut-defining emitters. Another method provides reduced power in an OLED display including a white-emitting layer with three color filters for gamut-defining emitters and two or more additional color filters for three additional within-gamut emitters.

Abstract: An organic electro-luminescent device package includes an organic electro-luminescent device array substrate, a transparent cover, and a frit. The organic electro-luminescent device array substrate includes a first substrate and a plurality of organic electro-luminescent devices arranged on the first substrate in an array. The transparent cover is disposed over the organic electro-luminescent device array substrate. The transparent cover includes a second substrate and a conductive layer disposed on the second substrate. The organic electro-luminescent devices are located between the first substrate and the second substrate. The frit is disposed between the organic electro-luminescent device array substrate and the transparent cover to surround the organic electro-luminescent devices. The frit is located between the first substrate and a portion of the conductive layer, and the portion of the conductive layer corresponding to the frit is transparent.

Abstract: An organic light emitting diode display device and the driving method thereof that is adaptive for increasing display quality. The organic light emitting diode display device according to an embodiment includes a display panel where pixels having an organic light emitting diode device are arranged in a matrix type and a data driver that supplies a data voltage and an inverted voltage to the pixels, where the inverted voltage is symmetric to the data voltage relative to a reference voltage.

Abstract: A method of removing offsets between channels of a liquid crystal panel is provided. The method includes: alternately arranging first type output buffers and second type output buffers for driving the pixels in units of at least two rows of the pixels; and arranging the first type output buffers and the second type output buffers in units of at least two columns of the pixels so that the output buffers with types opposite to those of previous two columns are arranged. The second type output buffers are embodied by switching connections among the differential transistors and connections among the load transistors in the first type output buffers.

Abstract: A display apparatus includes a data driver outputting a data current as image signals, a plurality of data lines for applying the data currents, and a plurality of pixel circuits coupled to the data lines At least one of the plurality of pixel circuits has a driving circuit outputting a current corresponding to the data current, a demultiplexer demultiplexing the output current of the driving circuit and outputting the output current to at least two output terminals, and at least two light emitting elements coupled to the at output terminals of the demultiplexer, and emitting light corresponding to an inputted current.

Abstract: A liquid crystal display is disclosed.

Abstract: After a sampling transistor is turned ON at a first timing when a control signal has risen, during a sampling period from a second timing when a video signal has risen from a reference potential to a signal potential to a third timing when the control signal has fallen and is turned OFF, the sampling transistor samples and writes the signal potential in a holding capacitance, and negatively feeds back a current flowing into a drive transistor during the sampling period to the holding capacitance and applies mobility correction of the drive transistor on the written signal potential. A signal driver adjusts the second timing for the video signal supplied to respective signal lines to correct a backward shift of the third timing due to a transmission delay along a scanning line of the control signal output from the control scanner.

Abstract: An offset voltage generating circuit sets an offset voltage through binary search based on a voltage value of the initial voltage, and a voltage controlling circuit generates an output voltage which is a predetermined gradation voltage added with the offset voltage, and applies a voltage based on the output voltage to a control terminal of a drive transistor. A current comparison circuit applies a supply voltage from a power supply to the other end of current path of the drive transistor. The current comparison circuit compares the current value of a reference current corresponding to the gradation voltage with a current value of the current flowing in the current path of the drive transistor at this time. The offset voltage generating circuit acquires a specific offset voltage corresponding to variation of the characteristic of the drive transistor based on a result of comparison performed by the current comparison circuit.

Abstract: According to one embodiment, a light-emitting device includes an emitting layer, first and second electrodes, a voltage-supply circuit, an ammeter and a controller. The emitting layer includes a solution containing an emitting material and a solvent. The first and second electrodes are in contact with the solution. The voltage-supply circuit applies an operating voltage between the first and second electrodes. The ammeter measures the amount of electric current flowing between the first and second electrodes. The controller controls the operation of the voltage-supply circuit such that the polarity of the operating voltage reverses and determining a timing of reversing the polarity based on the output of the ammeter.