JP2006189804A - Light-emitting device and electronic apparatus using the light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device which generates no potential change of a power supply line of a pixel portion, even if both the electrodes of a light-emitting element for monitoring are short-circuited. <P>SOLUTION: The light emitting device has a monitoring portion which detects changes in the ambient temperature and degradation with time, provided with a plurality of monitoring pixels and a monitoring line. Each of the plurality of monitoring pixels has a light-emitting element for monitoring, a constant current source, a switch, and a detecting circuit, and one electrode of the light-emitting element for monitoring is connected to the monitoring line via the switch. The detecting circuit controls the on and off of the switch, and specifically, when both electrodes of the light-emitting element for monitoring are short-circuited, the switch is turned off. The light-emitting device will not generate potential change in the power supply line of the pixel portion, even if both the electrodes of the light-emitting element for monitoring are short-circuited. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light emitting device and an electronic device having a self light emitting element.

  In recent years, the development of light-emitting devices including light-emitting elements typified by EL (Electro Luminescence) elements has been promoted, and a wide range of uses is expected by taking advantage of self-luminous type such as high image quality, wide viewing angle, thinness, and light weight. Has been. In general, a light-emitting element is a current-driven element, and the value of current flowing through the light-emitting element and the luminance of the light-emitting element are approximately proportional. For this reason, there is a display device that employs constant current driving in which a constant current is supplied to the light emitting element (see, for example, Patent Document 1).

  In addition, the light-emitting element has temperature dependency, and the resistance value decreases when the ambient temperature (hereinafter sometimes referred to as environmental temperature) becomes high, and the resistance value increases when the temperature becomes low. In addition, the light-emitting element has a property of deteriorating with time, and the resistance value increases due to deterioration with time (hereinafter sometimes referred to as deterioration with time). Thus, there is a light-emitting device that suppresses the influence of changes in environmental temperature and changes over time of the light-emitting element (see, for example, Patent Document 2).

The light emitting device described in Patent Document 2 includes a light emitting element, a power supply line, a buffer amplifier, a monitoring light emitting element, and a constant current source. A constant current is supplied to the monitor light emitting element from the constant current source. When the environmental temperature changes and the deterioration with time occurs, the current value of the monitor light emitting element does not change, and one of the electrodes of the monitor light emitting element does not change. The potential changes. Since one electrode of the monitor light emitting element is connected to the power supply line via the buffer amplifier, when the potential of one electrode of the monitor light emitting element changes in accordance with the change in environmental temperature and deterioration with time. The potential of the power supply line also changes. As described above, in the light-emitting device described in Patent Document 1, the resistance value of the light-emitting element due to the change in environmental temperature and the deterioration with time is changed by changing the potential of the power supply line in accordance with the change in environmental temperature and the deterioration with time. It is possible to suppress the influence due to the fluctuation of.
JP 2003-323159 A JP 2002-333861 A

  Electronic devices equipped with display functions such as information terminals and mobile phones have been widely used. However, many of these electronic devices use batteries, and power supply is limited. Reduction has become an issue. However, when constant current driving is employed as in the light-emitting device described in Patent Document 1, a driving transistor connected in series with the light-emitting element must be operated in a saturation region, and thus it is necessary to increase the driving voltage. As a result, power consumption increases. In view of the above circumstances, an object of the present invention is to provide a light-emitting device capable of reducing power consumption.

  The light-emitting element includes an anode, a cathode, and a layer containing a light-emitting material between the anode and the cathode (hereinafter sometimes referred to as an organic light-emitting layer). The organic light-emitting layer is thin, and the anode and the cathode are short-circuited (hereinafter sometimes referred to as a short-circuit between both electrodes) due to dust and other defects in the manufacturing process, during the initial stage of the light-emitting device and during use. Sometimes. In Patent Document 2, if a short-circuit between both electrodes occurs in the monitor light emitting element, the current supplied from the constant current source is concentrated on the shorted portion of the monitor light emitting element. Then, the potential of one electrode of the monitor light emitting element is lowered, the potential of the input portion of the buffer amplifier connected to one electrode of the monitor light emitting element is lowered, and the power supply line for supplying current to the light emitting element of the pixel portion is reduced. The potential also drops. That is, when a short-circuit between both electrodes occurs in the monitor light emitting element, the potential of the power supply line varies due to the influence. When the potential of the power supply line fluctuates, a desired voltage value is not applied between both electrodes of the light emitting element. If it does so, a light emitting element will not light-emit with desired brightness | luminance, but the precision of gradation display will fall.

  In view of the above circumstances, the present invention has a plurality (n, n is a natural number) of monitor light emitting elements, and even if (n-1) or less monitor light emitting elements are short-circuited between both electrodes, It is an object to provide a light-emitting device in which the potential of a power supply line in a pixel portion does not vary. It is another object of the present invention to provide a light-emitting device that can display an image accurately even if a short circuit between both electrodes occurs in a monitor light-emitting element.

  The light-emitting device of the present invention includes a first pixel, a monitor line, and a second pixel. The first pixel includes a first light-emitting element, a constant current source, a switch, and a circuit. The second pixel has a second light-emitting element, one electrode of the first light-emitting element is connected to the monitor line through a switch, and the circuit is connected to one of the first light-emitting elements. The switch is controlled to be turned on or off in accordance with the potential of the electrode, and the constant current source supplies current to the first light emitting element.

  In addition, another structure of the light-emitting device of the present invention includes a first pixel portion, a second pixel portion, and an amplifier. The first pixel portion includes a first pixel and a monitor line. The first pixel includes a first light-emitting element, a constant current source, a switch, and a circuit. The second pixel portion includes a power supply line and a second pixel. The pixel includes a second light-emitting element and a transistor. One electrode of the first light-emitting element is connected to a monitor line through a switch, and the circuit includes one electrode of the first light-emitting element. The on / off of the switch is controlled in accordance with the potential of one of the electrodes, one electrode of the second light emitting element is connected to the power supply line through the transistor, and the monitor line is connected to the power supply line through the amplifier The constant current source supplies current to the first light emitting element.

  In addition, another structure of the light-emitting device of the present invention includes a first pixel portion, a second pixel portion, and an amplifier. The first pixel portion includes a first pixel and a monitor line. The first pixel includes a first light emitting element, a constant current source, a first transistor, and an inverter. The second pixel portion includes a power supply line and a second pixel. The second pixel includes a second light-emitting element and a second transistor, and one electrode of the first light-emitting element is connected to the monitor line through the first transistor, and the constant current source Supplies current to the first light emitting element, the input terminal of the inverter is connected to one electrode of the first light emitting element, the output terminal of the inverter is connected to the gate electrode of the first transistor, and the inverter Is a voltage for controlling on or off of the first transistor in accordance with the potential of one electrode of the first light-emitting element. Is output to the gate electrode of the first transistor, one electrode of the second light-emitting element is connected to the power supply line via the second transistor, and the monitor line is supplied with power via the amplifier. It is connected to a line.

In the above structure, the second transistor operates in a linear region. The amplifier may be an operational amplifier, a sense amplifier, or a differential amplifier. The first light-emitting element and the second light-emitting element can be provided over the same insulating surface.
Note that a panel, a module, a portable terminal, a camera, a display, a television device, or the like can be manufactured using the light-emitting device having the above structure.

  The light-emitting device of the present invention includes a monitor unit that detects changes in environmental temperature and deterioration over time. The monitor unit has a plurality of monitor pixels and monitor lines. Each of the plurality of monitor pixels includes a monitor light emitting element, a constant current source, a separation switch, and a detection circuit. One electrode of the monitor light emitting element is connected to the monitor line via a separation switch. The constant current source supplies a constant current to the monitor light emitting element. The detection circuit is a circuit that controls on or off of the separation switch. Specifically, when both electrodes of the monitor light emitting element are short-circuited, the separation switch is turned off (non-conduction).

  The light-emitting device of the present invention having the above configuration will be described with reference to FIG. The monitor unit 107 includes a plurality of monitor pixels 100 and monitor lines 105. The monitor pixel 100 includes a monitor light emitting element 104, a constant current source 101, a separation switch 102, and a detection circuit 103.

  One of the anode and the cathode of the monitor light emitting element 104 is connected to the monitor line 105 via the separation switch 102. The other of the anode and the cathode of the monitor light emitting element 104 is connected to the common power source 115.

  The constant current source 101 supplies a constant current to the monitor light emitting element 104.

  The input terminal of the detection circuit 103 is connected to one electrode of the monitor light emitting element 104, and the output terminal of the detection circuit 103 is connected to the separation switch 102. The detection circuit 103 is a circuit that controls the on / off of the separation switch 102. More specifically, the detection circuit 103 controls the on / off of the separation switch 102 according to the potential of one of the anode and the cathode of the monitor light emitting element 104. When both electrodes of the monitor light emitting element 104 are short-circuited, a potential for turning off the separation switch 102 is output to the separation switch 102. When both electrodes of the monitor light emitting element 104 are not short-circuited, a potential for turning on the separation switch 102 is output to the separation switch 102.

  According to the present invention having the above-described configuration, the monitor light-emitting element 104 and the monitor light-emitting element 104 in which the short-circuit between the electrodes has occurred are detected by detecting the occurrence of a short-circuit between the electrodes. The connection with the line 105 can be made non-conductive. Therefore, even if a short-circuit between both electrodes occurs in the monitor light emitting element 104, the influence can be suppressed.

  In addition to the above structure, the light-emitting device of the present invention includes a buffer amplifier 106. An input unit of the buffer amplifier 106 is connected to the monitor line 105.

  In addition to the above structure, the light-emitting device of the present invention includes a pixel portion including a plurality of pixels and a power supply line. Each of the plurality of pixels includes a light emitting element and a driving transistor. One electrode of the light emitting element is connected to a power supply line through a driving transistor. The power supply line is connected to the output section of the buffer amplifier 106. A monitor line 105 included in the monitor unit 107 and a power supply line included in the pixel unit are connected via a buffer amplifier 106.

  As described above, in the present invention having the monitor unit 107 and the pixel unit, even if a short-circuit between both electrodes occurs in the monitor light emitting element 104, the potential of the monitor line 105 does not fluctuate due to the short-circuit between both electrodes. The potential of the power supply line in the unit does not change. Therefore, an image can be accurately displayed by the pixel portion.

  In addition, the driving transistor included in each of the plurality of pixels operates in a linear region. Further, the present invention employs constant voltage driving in which a constant voltage is applied to the light emitting element. In the constant voltage driving, it is not necessary to operate the driving transistor in the saturation region, and it is not necessary to increase the driving voltage. Therefore, power consumption can be reduced as compared with the constant current driving.

  The light-emitting element for monitoring 104 and the light-emitting element provided in the pixel portion are provided over the same insulating surface (on the same substrate). That is, the monitor light-emitting element 104 and the light-emitting element provided in the pixel portion are manufactured through the same process. Therefore, the characteristics with respect to environmental temperature and changes with time are the same or almost the same.

  The present invention also provides a panel using the light-emitting device having the above structure. A panel is in a state in which a plurality of pixels are sealed, and in many cases, corresponds to a state in which a plurality of pixels are sealed with a pair of substrates.

  The present invention provides a module using the light emitting device having the above structure. A module is a state in which a printed circuit board is connected to the above-described panel, and a plurality of IC chips corresponding to a controller circuit and a power supply circuit are mounted on the printed circuit board.

  The present invention provides a portable terminal using the light emitting device having the above-described configuration. The portable terminal corresponds to a cellular phone device (also referred to as a cellular phone or a cellular phone), a PDA (Personal Digital Assistant), an electronic notebook, a portable game machine, or the like.

  The present invention provides a digital camera using the light emitting device having the above structure. The structure of the light emitting device of the present invention is used as a display unit of a digital camera.

  The present invention provides a digital video camera using the light emitting device having the above structure. The structure of the light emitting device of the present invention is used as a display unit of a digital video camera.

  The present invention provides a display using the light emitting device having the above structure. The display corresponds to a display used as a personal computer monitor or an advertisement display monitor.

  The present invention provides a television device using the light emitting device having the above structure.

  According to the present invention having the monitor portion, it is possible to suppress the influence due to the variation of the resistance value of the light emitting element due to the environmental temperature and the change with time.

  According to the present invention having the monitor light emitting element, the constant current source, the separation switch, and the detection circuit, even if a short circuit between the two electrodes occurs in the monitor light emitting element, the potential of the monitor line does not change due to the short circuit between the two electrodes. Therefore, the potential of the power supply line that supplies power to the light emitting elements in the pixel portion can be kept normal. As a result, a light emitting device with improved reliability can be provided. Further, according to the present invention, the reliability of a product using the light emitting device can be improved. Accordingly, the product can be shipped with peace of mind.

  In addition, the present invention in which the driving transistor is operated in a linear region uses constant voltage driving, and the driving voltage of the light emitting element can be lowered as compared with the case where constant current driving is used, thereby reducing power consumption. can do.

Embodiments of the present invention will be described below with reference to the drawings. However, the present invention can be implemented in many different modes, and those skilled in the art can easily understand that the modes and details can be variously changed without departing from the spirit and scope of the present invention. Is done. Therefore, the present invention is not construed as being limited to the description of this embodiment mode. Note that in all the drawings for describing the embodiments, the same portions or portions having similar functions are denoted by the same reference numerals, and repetitive description thereof is omitted.
(Embodiment 1)

  The structure of the light-emitting device of the present invention will be described with reference to the drawings (see FIG. 2). The light-emitting device of the present invention includes a pixel portion 210, a monitor portion 217, a buffer amplifier 206, a source driver 208, and a gate driver 209.

  The pixel unit 210 includes a plurality of pixels 211. Each of the plurality of pixels 211 includes a light emitting element 214, a writing transistor 212, and a driving transistor 213. Note that each of the plurality of pixels 211 may include a capacitor that holds the gate-source voltage of the driving transistor 213 in addition to the above structure.

The light-emitting element 214 includes an anode, a cathode, and an electroluminescent layer sandwiched between the anode and the cathode. One of an anode and a cathode of the light-emitting element 214 is connected to a source electrode or a drain electrode of the driving transistor 213, and the other of the anode and the cathode of the light-emitting element 214 is connected to a common power source 215.
Here, the direction of the current flowing through the light emitting element 214 is such that the current flows from the electrode connected to the driving transistor 213 to the electrode not connected to the driving transistor 213, and the driving transistor of the light emitting element 214 A mode in which the electrode on the side connected to 213 serves as an anode and the electrode on the common power source 215 side through which current flows serves as a cathode will be described. Note that when the direction of the current flowing through the light-emitting element 214 is opposite, the polarity of the driving transistor 213 and the connection relationship between the driving transistor 213 and the light-emitting element 214 are changed as appropriate.

  The writing transistor 212 functions to capture the video signal from the source driver 208 into each pixel 211 in accordance with a signal from the gate driver 209. That is, the writing transistor 212 is a transistor that controls capturing of a video signal to the pixel 211.

The driving transistor 213 is a transistor that controls supply of current to the light-emitting element 214 in accordance with the potential of the captured video signal. Note that the driving transistor 213 operates in a linear region. Therefore, the potential applied to the electrode on the side connected to the driving transistor 213 of the light emitting element 214 is substantially equal to the potential of the power supply line 216, and the amount of current flowing through the light emitting element 214 is between the power supply line 216 and the common power source 215. Determined by potential difference.
The present invention in which the driving transistor 213 operates in a linear region employs constant voltage driving in which a constant voltage is applied to the light emitting element 214. In the constant voltage driving, it is not necessary to operate the driving transistor 213 in the saturation region and it is not necessary to increase the driving voltage, so that power consumption can be reduced compared to the constant current driving.

  The monitor unit 217 includes a plurality of monitor pixels 200, a monitor line 205, and a current value control circuit 207. Each of the plurality of monitor pixels 200 includes a monitor light emitting element 204, a constant current source 201, a detection inverter 203, and a separation switch 202.

  A plurality of monitor light emitting elements 204 are connected to the monitor line 205. Accordingly, the potential of the monitor line 205 is an average potential of one of the anode and cathode of the plurality of monitor light emitting elements 204.

  The monitor light-emitting element 204 includes an anode, a cathode, and an electroluminescent layer sandwiched between the anode and the cathode. One of the anode and the cathode of the monitor light emitting element 204 is connected to the monitor line 205 via the separation switch 202. The other of the anode and the cathode of the monitor light emitting element 204 is connected to a common power source 215. In this embodiment mode, a case will be described in which the electrode on the side connected to the constant current source 201 of the monitoring light-emitting element 204 is an anode, and the electrode on the side connected to the common power source 215 is a cathode. In this case, a current flows from the anode of the monitor light emitting element 204 to the cathode.

  The constant current source 201 is a P channel transistor. The source electrode of the P channel transistor is connected to a high potential power supply (VDD), and the gate electrode of the P channel transistor is connected to the current value control circuit 207. Note that the configuration of the constant current source 201 is not limited to the above configuration, and may include a current mirror circuit or a configuration including a transistor variation correction circuit.

  The isolation switch 202 is a P-channel transistor. Note that an element including a switching function may be used for the separation switch 202. Therefore, an N-channel transistor, an analog switch, or the like may be used instead of the P-channel transistor.

The detection inverter 203 has a P-channel transistor 203a and an N-channel transistor 203b connected in series. The source electrode of the P-channel transistor 203a is connected to the monitor line 205, and the source electrode of the N-channel transistor 203b is connected to a low potential power supply (GND).
Note that the source electrode of the P-channel transistor 203a may be connected to the power supply line 216. Further, the source electrode of the N-channel transistor 203b is not necessarily connected to the ground power supply (GND). Since the potential output from the detection inverter 203 may be any potential that can open and close the separation switch 202, a plurality of power supplies connected to the source electrode of the N-channel transistor 203 b are arranged in the vicinity of the monitor pixel 200. An appropriate power source may be used from among the power sources.
In addition, the detection circuit is not limited to the configuration using the detection inverter 203, and the short circuit between the two electrodes of the monitor light emitting element 204 is detected, and the separation switch 202 is turned on (conductive) or turned off (non-conductive). If so, another configuration may be used instead of the detection inverter 203.

  The current value control circuit 207 is connected to the constant current source 201. The current value supplied from the constant current source 201 is determined by the potential supplied from the current value control circuit 207, and the current flows to the monitoring light emitting element 204.

  The buffer amplifier 206 has an input unit and an output unit. An input unit of the buffer amplifier 206 is connected to the monitor line 205, and an output unit is connected to the power supply line 216. The buffer amplifier 206 is a circuit having high input impedance, equal input and output potentials, and high output current capacity (also referred to as current capability). The buffer amplifier 206 is a circuit with low output impedance. Therefore, any circuit having such characteristics can use another circuit instead of the buffer amplifier 206. For example, an amplifier such as an operational amplifier, a sense amplifier, or a differential amplifier can be used.

  In the above configuration, if the monitoring light emitting element 204 is not short-circuited between both electrodes, one potential of the anode and the cathode of the monitoring light emitting element 204 is applied to the input portion of the detection inverter 203. Then, the output of the detection inverter 203 becomes the GND potential, and the separation switch 202 is turned on (conductive state).

  On the other hand, when a short-circuit between both electrodes occurs in the monitor light emitting element 204, the potential of the input part of the detection inverter 203 becomes close to 0V. Then, the output of the detection inverter 203 becomes a potential for turning off the separation switch 202, and the separation switch 202 is turned off.

In the present invention having the above configuration, when a short circuit between the electrodes occurs in the monitor light emitting element 204, the separation switch 202 provided between the monitor line 205 and the monitor light emitting element 204 is turned off. The potential of the monitor light emitting element 204 is not transmitted to the monitor line 205. Therefore, the potential of the monitor line 205 does not fluctuate due to a short circuit between the two electrodes generated in the monitor light emitting element 204.
That is, even if a short-circuit between both electrodes occurs in the monitor light emitting element 204, the potential of the monitor line 205, that is, the power supply line 216 that supplies power to the light emitting element 214 of the pixel portion 210 can continue to maintain a normal potential. it can. The present invention having the above-described configuration contributes to improving the reliability of the light emitting device.

  In the above configuration, the monitor pixel 200 is provided between the pixel portion 210 and the gate driver 209, but the position where the monitor pixel 200 is provided is not particularly limited. For example, it may be provided between the source driver 208 and the pixel portion 210.

  In addition, the current value control circuit 207, the buffer amplifier 206, the source driver 208, and the gate driver 209 may be provided over a substrate having the same insulating surface, or some circuits may be provided over another substrate.

  In this embodiment, the case where the light emitting element 214 is a single color has been described. However, when there are a plurality of light emitting elements such as red, green, and blue, the monitor pixel 200, the buffer amplifier 206, and the power supply line 216 are naturally included. It is necessary to provide more than one.

  Further, in this embodiment mode, it has been described that a current always flows through the monitor light emitting element 204. However, control may be performed so that a current flows intermittently through the monitor light emitting element 204. However, it is needless to say that the design should be such that the potential of the input portion of the buffer amplifier 206 is held during a period in which no current flows through the monitor light emitting element 204.

In the above embodiment, the structure of the active matrix light-emitting device of the present invention is described; however, the present invention can also be applied to a passive matrix light-emitting device. A passive matrix light-emitting device includes a pixel portion, a column signal line driver circuit, and a row signal line driver circuit provided over a substrate. The pixel portion includes column signal lines arranged in the column direction, row signal lines arranged in the row direction, and a plurality of light emitting elements arranged in a matrix. By providing the monitor unit and the buffer amplifier on the same substrate on which the pixel unit is formed, the effect of the present invention can be obtained.
(Embodiment 2)

  A cross-sectional structure and a top surface structure of a light-emitting device of the present invention will be described with reference to the drawings. More specifically, a cross-sectional structure and a top structure of a light-emitting device including a writing transistor 212, a driving transistor 213, a light-emitting element 214, and a capacitor 219 will be described with reference to FIGS.

  As the substrate 20 having an insulating surface, a glass substrate, a quartz substrate, a stainless steel substrate, or the like can be used. In addition, a substrate made of a plastic such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN) or a flexible synthetic resin such as acrylic can be used as long as it can withstand the processing temperature in the manufacturing process.

  First, a base film is formed on the substrate 20. As the base film, an insulating film such as silicon oxide, silicon nitride, or silicon nitride oxide can be used. Next, an amorphous semiconductor film is formed over the base film. The thickness of the amorphous semiconductor film is 25 to 100 nm. As the amorphous semiconductor, not only silicon but also silicon germanium can be used. Subsequently, the amorphous semiconductor film is crystallized as necessary to form a crystalline semiconductor film. As a method for crystallization, a heating furnace, laser irradiation, irradiation of light emitted from a lamp, or a combination thereof can be used. For example, a crystalline semiconductor film is formed by adding a metal element to an amorphous semiconductor film and performing heat treatment using a heating furnace. Thus, it is preferable to add a metal element because crystallization can be performed at a low temperature.

  Next, the crystalline semiconductor film is selectively etched so as to have a predetermined shape. Next, an insulating film functioning as a gate insulating film is formed. The insulating film is formed with a thickness of 10 to 150 nm so as to cover the semiconductor film. For example, a silicon oxynitride film, a silicon oxide film, or the like can be used, and a single layer structure or a stacked structure may be used.

  Next, a conductive film functioning as a gate electrode is formed through the gate insulating film. The gate electrode may be a single layer or a stacked layer, but here, the gate electrodes are formed by stacking the conductive films 22a and 22b. The conductive films 22a and 22b are composed of an element selected from tantalum (Ta), tungsten (W), titanium (Ti), molybdenum (Mo), aluminum (Al), and copper (Cu), or these elements as a main component. It is made of alloy material or compound material. In this embodiment, a tantalum nitride film with a thickness of 10 to 50 nm is formed as the conductive film 22a, and a tungsten film with a thickness of 200 to 400 nm is formed as the conductive film 22b.

  Next, an impurity element is added using the gate electrode as a mask to form an impurity region. At this time, a low concentration impurity region may be formed in addition to the high concentration impurity region. The low concentration impurity region is called an LDD (Lightly Doped Drain) region.

  Next, insulating films 28 and 29 that function as the interlayer insulating film 30 are formed. The insulating film 28 is preferably an insulating film containing nitrogen. Here, the insulating film 28 is formed using a 100 nm silicon nitride film by a plasma CVD method. The insulating film 29 is preferably formed using an organic material or an inorganic material. As the organic material, polyimide, acrylic, polyamide, polyimide amide, benzocyclobutene, siloxane, or polysilazane can be used. Siloxane has a skeletal structure with a bond of silicon (Si) and oxygen (O), and an organic group containing at least hydrogen (for example, an alkyl group or aromatic hydrocarbon) is used as a substituent. Further, a fluoro group may be used as a substituent. Further, as a substituent, an organic group containing at least hydrogen and a fluoro group may be used. Polysilazane is formed using a polymer material having a bond of silicon (Si) and nitrogen (N), that is, a liquid material containing polysilazane as a starting material. Examples of the inorganic material include oxygen such as silicon oxide (SiOx), silicon nitride (SiNx), silicon oxynitride (SiOxNy) (x> y), and silicon nitride oxide (SiNxOy) (x> y) (x and y are natural numbers). Alternatively, an insulating film containing nitrogen can be used. Note that a film made of an organic material has good flatness, but moisture and oxygen are absorbed by the organic material. In order to prevent this, an insulating film containing an inorganic material is preferably formed over the insulating film made of an organic material.

  Next, after forming contact holes in the interlayer insulating film 30, the conductive film 24 functions as the source wiring and drain wiring of the writing transistor 212, the source wiring and drain wiring of the driving transistor 213, the signal line Sx, and the power supply line Vx. Form. As the conductive film 24, a film made of an element of aluminum (Al), titanium (Ti), molybdenum (Mo), tungsten (W), or silicon (Si) or an alloy film using these elements can be used. In this embodiment, a stacked film of a titanium film, a titanium nitride film, a titanium-aluminum alloy film, and a titanium film is formed.

Next, an insulating film 31 is formed so as to cover the conductive film 24. The material shown for the interlayer insulating film 30 can be used for the insulating film 31. Next, a pixel electrode (also referred to as a first electrode) 19 is formed in the opening provided in the insulating film 31. In order to improve the step coverage of the pixel electrode 19 in the opening, the end face of the opening may be rounded so as to have a plurality of radii of curvature. The pixel electrode 19 is made of indium tin oxide (ITO), IZO (Indium Zinc Oxide) in which 2 to 20 at% zinc oxide is mixed with indium oxide, and 2 to 20 at. % Silicon oxide (SiO ₂ ), organic indium, organic tin, or the like can be used. In addition to silver (Ag), an element selected from tantalum, tungsten, titanium, molybdenum, aluminum, and copper, or an alloy material or a compound material containing these elements as a main component is used as a non-translucent material. Can do. At this time, when the insulating film 31 is formed using an organic material and the flatness is increased, the flatness of the pixel electrode formation surface is improved, so that a voltage can be uniformly applied to the light-emitting element 214. A short circuit of the light emitting element 214 can be prevented.

  Next, the electroluminescent layer 33 is formed by a vapor deposition method or an inkjet method. The electroluminescent layer 33 includes an organic material or an inorganic material, and includes an electron injection layer (EIL), an electron transport layer (ETL), a light emitting layer (EML), a hole transport layer (HTL), and a hole injection layer (HIL). ) And the like. Note that the boundaries between the layers are not necessarily clear, and there are cases where the materials constituting the layers are partially mixed and the interface is unclear.

  Then, a counter electrode (also referred to as a second electrode) 35 is formed by a sputtering method or an evaporation method. One of the pixel electrode 19 and the counter electrode 35 is an anode, and the other is a cathode.

  As the anode material, it is preferable to use a metal, an alloy, an electrically conductive compound, a mixture thereof, or the like having a high work function (work function of 4.0 eV or more). Specific examples of anode materials include ITO (indium tin oxide), indium oxide mixed with 2 to 20 at% zinc oxide (ZnO), IZO (Indium Zinc Oxide), gold (Au), platinum (Pt). , Nickel (Ni), tungsten (W), chromium (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), or metal nitride (TiN, etc.) ) Etc.

On the other hand, as the cathode material, it is preferable to use a metal, an alloy, an electrically conductive compound, a mixture thereof, or the like having a low work function (work function of 3.8 eV or less). Specific examples of the cathode material include elements belonging to Group 1 or Group 2 of the element periodic rule, that is, alkali metals such as lithium (Li) and cesium (Cs), and magnesium (Mg), calcium (Ca), and strontium (Sr In addition to alkaline earth metals such as) and alloys containing these (Mg: Ag, Al: Li) and compounds (lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF ₂ )), It can be formed using a transition metal including a rare earth metal. However, since the cathode needs to have translucency, these metals or alloys containing these metals are formed very thin, and are formed by lamination with metals (including alloys) such as ITO (indium tin oxide). To do.

Thereafter, a protective film made of a silicon nitride film or a DLC (Diamond Like Carbon) film may be provided so as to cover the counter electrode 35. The light emitting device of the present invention is completed through the above steps.
(Embodiment 3)

  A panel which is an embodiment of the light emitting device of the present invention will be described. Over the substrate 20, a pixel portion 210 including a plurality of pixels including the light-emitting element 214, gate drivers 209 and 218, a source driver 208, and a connection film 407 are provided (see FIG. 5A). The connection film 407 is connected to an external circuit (IC chip).

  FIG. 5B is a cross-sectional view taken along the line AB of the panel, and shows a driving transistor 213, a light emitting element 214, a capacitor 219 provided in the pixel portion 210, and a CMOS circuit 410 provided in the source driver 208. . A sealant 408 is provided around the pixel portion 210, the gate drivers 209 and 218, and the source driver 208, and the light-emitting element 214 is sealed with the sealant 408 and the counter substrate 406. This sealing process is a process for protecting the light-emitting element 214 from moisture. Here, a method of sealing with a cover material (glass, ceramics, plastic, metal, or the like) is used, but a thermosetting resin or ultraviolet light is used. A method of sealing with a curable resin or a method of sealing with a thin film having a high barrier ability such as a metal oxide or a nitride may be used. The element formed on the substrate 20 is preferably formed of a crystalline semiconductor (polysilicon) having favorable characteristics such as mobility as compared with an amorphous semiconductor, so that monolithic formation on the same surface can be achieved. Realized. Since the number of external ICs to be connected is reduced, the panel having the above structure can be small, light, and thin.

Note that in the case where the pixel electrode of the light-emitting element 214 has a light-transmitting property and the counter electrode of the light-emitting element 214 has a light-blocking property, the light-emitting element 214 performs bottom emission (see FIG. 5B).
In addition, when the pixel electrode of the light-emitting element 214 has a light-shielding property and the counter electrode of the light-emitting element 214 has a light-transmitting property, the light-emitting element 214 performs top emission (see FIG. 6A).
In addition, when both the pixel electrode of the light-emitting element 214 and the counter electrode of the light-emitting element 214 have a light-transmitting property, the light-emitting element 214 performs dual emission (see FIG. 6B).

  5B, an insulating layer is provided over the source / drain wiring of the driving transistor 213, and the pixel electrode of the light-emitting element 214 is provided over the insulating layer. However, the present invention is not limited to this structure, and the pixel electrode of the light-emitting element 214 may be provided in the same layer as the source / drain wiring of the driving transistor 213 (see FIGS. 6A and 6B). In addition, in the portion where the source / drain wiring of the driving transistor 213 and the pixel electrode of the light emitting element 214 are stacked, the source / drain wiring of the driving transistor 213 may be a lower layer and the pixel electrode of the light emitting element 214 may be an upper layer (see FIG. 6A), the pixel electrode of the light-emitting element 214 may be a lower layer, and the source / drain wiring of the driving transistor 213 may be an upper layer (see FIG. 6B).

  Note that the pixel portion 210 is configured by a TFT using an amorphous semiconductor (amorphous silicon) formed on an insulating surface as a channel portion, and the gate drivers 209 and 218 and the source driver 208 may be configured by an IC chip. Good. The IC chip may be bonded to the substrate 20 by a COG (Chip on Glass) method, or may be bonded to the connection film 407 connected to the substrate 20. An amorphous semiconductor can be easily formed on a large-area substrate by using the CVD method and does not require a crystallization step, so that an inexpensive panel can be provided. At this time, if a conductive layer is formed by a droplet discharge method typified by an ink jet method, a cheaper panel can be provided.

  The light-emitting element included in the light-emitting device of the present invention includes, in its category, an element whose luminance is controlled by current or voltage. Specifically, the light-emitting element is used for OLED (Organic Light Emitting Diode) and FED (Field Emission Display). MIM type electron source elements (electron emitting elements) and the like are included. An OLED that is one of light-emitting elements includes a layer containing an electroluminescent material (hereinafter, abbreviated as an electroluminescent layer) from which luminescence generated by applying an electric field is obtained, an anode, and a cathode. Yes. The electroluminescent layer is provided between the anode and the cathode, and is composed of a single layer or a plurality of layers. In some cases, these layers contain an inorganic compound. Luminescence in the electroluminescent layer includes light emission (fluorescence) when returning from the singlet excited state to the ground state and light emission (phosphorescence) when returning from the triplet excited state to the ground state.

As the transistor used in the light-emitting device of the present invention, a thin film transistor using a polycrystalline semiconductor, a microcrystalline semiconductor (including a semi-amorphous semiconductor), or an amorphous semiconductor can be used, but the transistor is used in the light-emitting device of the present invention. The transistor is not limited to a thin film transistor. A transistor formed using single crystal silicon or a transistor using SOI (Silicon On Insulator) may be used. Further, a transistor using an organic semiconductor or a transistor using carbon nanotubes may be used. In addition, the transistor provided in the pixel of the light-emitting device of the present invention may have a single gate structure, a double gate structure, or a multi-gate structure having more gate electrodes.
(Embodiment 4)

  One mode of an electronic device using the light-emitting device of the present invention will be described with reference to FIGS. The electronic device illustrated here is a mobile phone device, and includes housings 2700 and 2706, a panel 2701, a housing 2702, a printed wiring board 2703, operation buttons 2704, and a battery 2705 (see FIG. 7). The panel 2701 has a pixel portion in which a plurality of pixels are arranged in a matrix, and the pixel portion is sealed with a pair of substrates. The panel 2701 is detachably incorporated in the housing 2702, and the housing 2702 is fitted on the printed wiring board 2703. The shape and dimensions of the housing 2702 are changed as appropriate in accordance with the electronic device in which the panel 2701 is incorporated. A plurality of IC chips corresponding to one or more selected from a central processing unit (CPU), a controller circuit, a power supply circuit, a buffer amplifier, a source driver, and a gate driver are mounted on the printed wiring board 2703. A module corresponds to a state where a printed wiring board 2703 is mounted on a panel 2701.

  The panel 2701 is connected to the printed wiring board 2703 through the connection film 2708. The panel 2701, the housing 2702, and the printed wiring board 2703 are housed in the housings 2700 and 2706 together with the operation buttons 2704 and the battery 2705. A pixel portion included in the panel 2701 is arranged so as to be visible from an opening window provided in the housing 2700.

  Note that the housings 2700 and 2706 are examples of the appearance of a mobile phone device, and the electronic device according to this embodiment can be transformed into various modes depending on functions and uses. Therefore, an example of an aspect of the electronic device will be described below with reference to FIG.

  A cellular phone device which is a portable terminal includes a pixel portion 9102 and the like (see FIG. 8A). A portable game device which is a portable terminal includes a pixel portion 9801 and the like (see FIG. 8B). The digital video camera includes pixel portions 9701 and 9702 and the like (see FIG. 8C). A PDA (Personal Digital Assistant) which is a portable information terminal includes a pixel portion 9201 and the like (see FIG. 8D). The television device includes a pixel portion 9301 and the like (see FIG. 8E). The monitor device includes a pixel portion 9401 and the like (see FIG. 8F).

  The present invention relates to a mobile phone device (also referred to as a mobile phone or a mobile phone) which is a mobile terminal, a PDA, an electronic notebook, a portable game machine, a television device (also referred to as a television or a television receiver), a display (a monitor device). It can also be applied to various electronic devices such as cameras such as digital cameras and digital video cameras, sound playback devices such as car audio, and home game machines. This embodiment mode can be freely combined with the above embodiment modes.

The figure which shows the light-emitting device of this invention. The figure which shows the light-emitting device of this invention. FIG. 6 illustrates a top structure of a light-emitting device of the present invention. FIG. 6 shows a cross-sectional structure of a light-emitting device of the present invention. The figure which shows the light-emitting device of this invention. The figure which shows the light-emitting device of this invention. FIG. 16 illustrates an electronic device of the invention. FIG. 16 illustrates an electronic device of the invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Monitor pixel 101 Constant current source 102 Separation switch 103 Detection circuit 104 Monitor light emitting element 105 Monitor line 106 Buffer amplifier 107 Monitor part 115 Common power supply

Claims (13)

A first pixel, a monitor line, and a second pixel;
The first pixel includes a first light emitting element, a constant current source, a switch, and a circuit.
The second pixel has a second light emitting element,
One electrode of the first light emitting element is connected to the monitor line via the switch,
The circuit controls on or off of the switch according to the potential of one electrode of the first light emitting element,
The light emitting device, wherein the constant current source supplies a current to the first light emitting element. A first pixel portion, a second pixel portion, and an amplifier;
The first pixel portion includes a first pixel and a monitor line,
The first pixel includes a first light emitting element, a constant current source, a switch, and a circuit.
The second pixel portion includes a power supply line and a second pixel,
The second pixel includes a second light emitting element and a transistor,
One electrode of the first light emitting element is connected to the monitor line via the switch,
The circuit controls on or off of the switch according to the potential of one electrode of the first light emitting element,
One electrode of the second light emitting element is connected to the power supply line through the transistor,
The monitor line is connected to the power supply line via the amplifier,
The light emitting device, wherein the constant current source supplies current to the first light emitting element. A first pixel portion, a second pixel portion, and an amplifier;
The first pixel portion includes a first pixel and a monitor line,
The first pixel includes a first light emitting element, a constant current source, a first transistor, and an inverter.
The second pixel portion includes a power supply line and a second pixel,
The second pixel includes a second light emitting element and a second transistor,
One electrode of the first light emitting element is connected to the monitor line through the first transistor,
The constant current source supplies current to the first light emitting element,
An input terminal of the inverter is connected to one electrode of the first light emitting element,
An output terminal of the inverter is connected to a gate electrode of the first transistor;
The inverter outputs a potential for controlling on or off of the first transistor to the gate electrode of the first transistor in accordance with the potential of one electrode of the first light emitting element.
One electrode of the second light emitting element is connected to the power supply line through the second transistor,
The light-emitting device, wherein the monitor line is connected to the power supply line through the amplifier.   3. The light-emitting device according to claim 2, wherein the transistor operates in a linear region.   4. The light-emitting device according to claim 3, wherein the second transistor operates in a linear region.   6. The light-emitting device according to claim 2, wherein the amplifier is an operational amplifier, a sense amplifier, or a differential amplifier. In any one of Claims 1 thru | or 6,
The light-emitting device, wherein the first light-emitting element and the second light-emitting element are provided on the same insulating surface.   A panel using the light emitting device according to claim 1.   A module using the light emitting device according to claim 1.   A portable terminal using the light emitting device according to claim 1.   A camera using the light emitting device according to any one of claims 1 to 7.   A display using the light emitting device according to any one of claims 1 to 7.   A television apparatus using the light-emitting device according to claim 1.

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