JP2005099745A - Semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To propose a semiconductor device that can supply an accurate current without the influence of variations even when a small signal current in a transistor for supplying a current to a pixel comprising an EL element. <P>SOLUTION: When the current is supplied to the pixel, a precharge voltage is supplied in advance. Subsequently, the signal writing is completed quickly. In addition, the precharge voltage is outputted from a circuit for supplying voltage and current that supplies a current to a current source circuit for supplying a current to the pixel. As the precharge voltage, a gate voltage of a transistor for supplying a current to the current source circuit is supplied to the pixel. At this time, optimum precharge voltage can be outputted by making W/L of a transistor in the pixel and W/L of a transistor for supplying current from the circuit for supplying voltage and current approximately equivalent to each other. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a semiconductor device having a function of controlling a current supplied to a load with a transistor, and particularly includes a pixel formed of a current-driven light-emitting element whose luminance changes depending on the current and a circuit for supplying a signal to the pixel The present invention relates to a semiconductor device.

  In a display device using a self-luminous light emitting element represented by an organic light emitting diode (also referred to as an organic light emitting diode (OLED), an organic EL element, or an electro luminescence (EL) element), as a driving method thereof. A simple matrix system and an active matrix system are known. Although the former has a simple structure, there is a problem that it is difficult to realize a large-sized and high-brightness display. In recent years, an active matrix system in which a current flowing through a light emitting element is controlled by a thin film transistor (TFT) provided in a pixel circuit is used. Development is underway.

In the case of an active matrix display device, a problem has been recognized that the current flowing through the light-emitting element changes due to variations in the current characteristics of the driving TFT, resulting in variations in luminance. In other words, a driving TFT that drives a current flowing through the light emitting element is used in the pixel circuit, and the current flowing through the light emitting element changes due to variations in characteristics of these driving TFTs, resulting in variations in luminance. It was. Therefore, even if the characteristics of the driving TFT in the pixel circuit vary, the current flowing through the light emitting element does not change, and various circuits for suppressing variations in luminance have been proposed (for example, see Patent Documents 1 to 4).
Patent Application Publication No. 2002-517806 International Publication No. 01/06484 Pamphlet Patent Application Publication No. 2002-514320 International Publication No. 02/39420 Pamphlet

  Patent Documents 1 to 3 disclose circuit configurations for preventing fluctuations in the current value flowing through the light emitting element due to variations in characteristics of the driving TFTs arranged in the pixel circuit. This configuration is called a current writing type pixel or a current input type pixel. Patent Document 4 discloses a circuit configuration for suppressing changes in signal current due to variations in TFTs in a source driver circuit.

  FIG. 6 shows a first configuration example of a conventional active matrix display device disclosed in Patent Document 1. The pixel in FIG. 6 includes a source signal line 601, first to third gate signal lines 602 to 604, a current supply line 605, TFTs 606 to 609, a storage capacitor 610, an EL element 611, and a video signal input current source 612. .

  The operation from signal current writing to light emission will be described with reference to FIG. In the figure, the figure numbers indicating the respective parts are the same as those in FIG. 7A to 7C schematically show the current flow. FIG. 7D shows the relationship between the currents flowing through the respective paths when signal current is written. FIG. 7E shows the voltage accumulated in the storage capacitor 610 when signal current is written, that is, TFT 608. This shows the gate-source voltage.

  First, a pulse is input to the first gate signal line 602 and the second gate signal line 603, and the TFTs 606 and 607 are turned on. At this time, a current flowing through the source signal line 601, that is, a signal current is Idata.

  Since the current Idata flows through the source signal line 601, the current path is divided into I1 and I2 in the pixel as shown in FIG. 7A. These relationships are shown in FIG. Needless to say, Idata = I1 + I2.

  At the moment when the TFT 606 is turned on, no charge is held in the storage capacitor 610, so the TFT 608 is turned off. Therefore, I2 = 0 and Idata = I1. That is, during this time, only a current due to charge accumulation in the storage capacitor 610 flows.

  Thereafter, electric charges are gradually accumulated in the storage capacitor 610, and a potential difference starts to occur between the two electrodes (FIG. 7E). When the potential difference between the two electrodes becomes Vth (point A in FIG. 7E), the TFT 608 is turned on and I2 is generated. As described above, since Idata = I1 + I2, I1 gradually decreases, but current still flows, and charge is accumulated in the storage capacitor 610.

  In the storage capacitor 610, charge accumulation continues until the potential difference between the two electrodes, that is, the gate-source voltage of the TFT 608 reaches a desired voltage, that is, a voltage (VGS) that allows the TFT 608 to pass an Idata current. . When the accumulation of the electric charge is finished (point B in FIG. 7E), the current I1 stops flowing, and further, the current corresponding to the VGS flows in the TFT 608, and Idata = I2 (FIG. 7B). . Thus, a steady state is reached. Thus, the signal writing operation is completed. Finally, selection of the first gate signal line 602 and the second gate signal line 603 is completed, and the TFTs 606 and 607 are turned off. Such an operation is called a setting operation.

  Subsequently, the light emission operation is started. A pulse is input to the third gate signal line 604, and the TFT 609 is turned on. Since the VGS written earlier is held in the holding capacitor 610, the TFT 608 is turned on, and a current of Idata flows from the current supply line 605. As a result, the EL element 611 emits light. At this time, if the TFT 608 operates in the saturation region, even if the source-drain voltage of the TFT 608 changes, Idata can flow without change.

  Such an operation for outputting the set current is referred to as an output operation. As a merit of the current writing type pixel, even when the characteristics of the TFT 608 are varied, the storage capacitor 610 holds a gate-source voltage necessary for flowing the current Idata, so that a desired voltage can be obtained. The current can be supplied to the EL element 611 accurately, and therefore, it is possible to suppress the luminance variation due to the TFT characteristic variation.

The above example relates to a technique for correcting a change in current due to variations in drive TFTs in a pixel circuit, but the same problem occurs in a source driver circuit. Patent Document 4 discloses a circuit configuration for preventing a change in signal current due to manufacturing variations of TFTs in a source driver circuit.
Patent Application Publication No. 2003-66908

  Further, in Patent Document 5, a voltage source is prepared in addition to a current source for controlling gradation, and a voltage source is supplied at the beginning of a row selection period by power source switching means for switching between two power sources input to the source signal line. Discloses a configuration in which the stray capacitance is changed instantaneously, and then gradation display is performed by a current source in order to obtain a desired luminance.

  However, since the parasitic capacitance of the wiring used for supplying the signal current to the driving TFT and the light emitting element is extremely large, when the signal current is small, the time constant for charging the parasitic capacitance of the wiring is increased, and the signal writing speed is increased. There is a problem that it becomes slow. That is, even if a signal current is supplied to the transistor, it takes a long time to generate a voltage necessary to flow the transistor at the gate terminal, and the signal writing speed becomes slow. Yes.

  Thus, Patent Document 5 discloses a configuration in which the charge of the source signal line is instantaneously changed, but the voltage value supplied at the beginning of the row selection period is not optimal. In addition, the configuration has become complicated.

  In view of such problems, the present invention reduces the influence of transistor characteristic variation, can supply a predetermined current, and can sufficiently improve the signal writing speed even when the signal current is small. An object is to provide an apparatus.

  The present invention achieves the above object by supplying an optimal voltage in advance when a current is input to a pixel.

  The present invention is a semiconductor device including a circuit for controlling a current supplied to a load by a transistor, wherein the source or drain of the transistor is connected to a current source circuit, and current is supplied from the current source circuit to the transistor. And an amplifying circuit for controlling the gate-source voltage and the drain-source voltage of the transistor.

  The present invention is configured such that a voltage / current supply circuit supplies a current to a current storage circuit, a voltage is supplied from a voltage / current supply circuit to a load, and a current is supplied from the current storage circuit. is there.

  The present invention includes a current storage circuit having means for supplying current to a load, and a voltage / current supply circuit having means for supplying current to the current storage circuit and means for supplying voltage to the load. It is characterized by this.

  The present invention is characterized in that the voltage / current supply circuit supplies a voltage to the load via the voltage storage circuit by the above-described configuration. The voltage supplied to the load can be a precharge voltage to the load.

  As the load, an element controlled by a current or a current signal is suitable, and a light-emitting element whose emission luminance can be changed by the current is a representative example. In the present invention, a display device or the like in which such a light-emitting element is provided in one pixel and arranged in a matrix can be formed.

  When a current or voltage is input, the voltage / current supply circuit has a function of supplying a current corresponding to the signal and supplying a precharge voltage. The precharge voltage has an optimum magnitude so that the current supplied from the voltage / current supply circuit can be written quickly.

  The current storage circuit has a function of inputting a current from a storage current input terminal and outputting a current having a magnitude corresponding to the input current from the storage current output terminal. In addition, even when no current is input, since a signal corresponding to the current is stored, a current having a magnitude corresponding to the input current can be output from the storage current output terminal. .

  In the present invention, there are no limitations on the types of transistors that can be used, and the transistor is formed using a thin film transistor (TFT) using a non-single-crystal semiconductor film typified by amorphous silicon or polycrystalline silicon, a semiconductor substrate, or an SOI substrate. MOS transistors, junction transistors, transistors using organic semiconductors or carbon nanotubes, and other transistors can be used. There is no limitation on the kind of the substrate over which the transistor is provided, and the transistor can be provided over a single crystal substrate, an SOI substrate, a glass substrate, or the like.

  In the present invention, being connected is synonymous with being electrically connected. Therefore, in the configuration disclosed by the present invention, in addition to a predetermined connection relationship, another element (for example, another element or a switch) that enables electrical connection may be disposed therebetween.

  In the present invention, when a current is supplied to the pixel, a precharge voltage is supplied in advance. Therefore, the writing of current is completed quickly. In addition, since the precharge voltage is output from a circuit that supplies current to the pixel, an appropriate voltage can be supplied.

(Embodiment 1)
In the present invention, a pixel is formed using an element whose light emission luminance can be controlled by a value of a current flowing through the light emitting element. Typically, an EL element can be used. Although there are various known EL element configurations, any element structure can be applied to the present invention as long as the emission luminance can be controlled by the current value. That is, an EL element is formed by freely combining a light emitting layer, a charge transport layer, or a charge injection layer. As a material therefor, a low molecular weight organic material, a medium molecular weight organic material (without sublimation, In addition, an organic light-emitting material having a number of molecules of 20 or less or a chained molecule length of 10 μm or less) or a polymer organic material can be used. Moreover, you may use what mixed or disperse | distributed the inorganic material to these.

In the present invention, a video signal voltage having a magnitude corresponding to display and a video signal current having a magnitude corresponding to display are supplied to a current source circuit disposed in a pixel, a signal line driver circuit, or the like. The video signal voltage and the video signal current have a magnitude related to each other. First, a circuit for supplying a video signal voltage and a video signal current will be described.

  However, the present invention is not limited to the video signal voltage and the video signal current, and can be applied to a circuit that supplies a voltage of another signal and a current of another signal.

  The circuit for supplying the video signal voltage and the video signal current may be the configuration shown in FIG. 1, the configuration shown in FIG. 2, the configuration shown in FIG. 3, the configuration shown in FIG. Since these details are described in Japanese Patent Application No. 2003-273765, the contents thereof can be combined with the present application. In the present application, first, this circuit will be briefly described.

  In FIG. 1, a voltage / current supply circuit 211 receives a signal from an original signal input terminal 212. In response to the signal, a signal current is output from the current output terminal 213 and a signal voltage is output from the voltage output terminal 214. The current output terminal 213 and the voltage output terminal 214 are connected to the input terminal 222 of the set circuit 221 via the switches 201 and 202.

  The set circuit 221 is precharged using the signal voltage supplied from the voltage output terminal 214 of the voltage / current supply circuit 211, and then uses the signal current supplied from the current output terminal 213 of the voltage / current supply circuit 211. Current is set. As a result, the set circuit 221 can supply an accurate current almost without being affected by variations in the current characteristics of the transistors constituting the circuit.

  The signal voltage supplied from the voltage output terminal 214 of the voltage / current supply circuit 211 is a steady state when the signal current is supplied from the current output terminal 213 of the voltage / current supply circuit 211 to the set circuit 221. That is, the voltage value is almost the same as when the signal writing is completed. Therefore, by supplying a signal voltage from the voltage output terminal 214 and precharging it, when a signal current is subsequently supplied from the current output terminal 213 of the voltage / current supply circuit 211, a steady state can be quickly established.

  That is, the magnitude of the signal voltage supplied from the voltage output terminal 214 of the voltage / current supply circuit 211 and the magnitude of the signal current supplied from the current output terminal 213 of the voltage / current supply circuit 211 are related to each other. ing.

  When supplying current from the current output terminal 213 of the voltage / current supply circuit 211 to the input terminal 222 of the circuit 221 to be set, it is necessary to pay attention to the direction of the current. That is, when a current flows from the voltage / current supply circuit 211 to the outside (referred to as a discharge type), the set circuit 221 causes a current to flow in (referred to as a suction type). It is necessary to keep. In this case, the voltage / current supply circuit 211 has a higher potential, and a current flows from the voltage / current supply circuit 211 to the set circuit 221. Further, when a current flows in from the voltage / current supply circuit 211 (in the case of a suction type), the set circuit 221 needs to allow the current to flow to the outside (in the case of a discharge type). In this case, the voltage / current supply circuit 211 has a lower potential, and a current flows from the set circuit 221 to the voltage / current supply circuit 211.

  When both the voltage / current supply circuit 211 and the set circuit 221 are of the suction type or the discharge type, the current flow is not normal, so that the circuit does not operate normally. Therefore, it is necessary to adjust whether the voltage / current supply circuit 211 and the set circuit 221 are the suction type or the discharge type.

  First, the configuration of the set circuit 221 will be briefly described. 5 and 8 show configuration examples of the set circuit 221 in the case of the discharge type. FIG. 5 shows the case where the transistor 501 which operates as a current source is a P-channel type, and FIG. 8 shows the case where the transistor 801 is an N-channel type. In this case, since it is a discharge type, the potential of the wiring 502 is high.

  The capacitor elements 503 and 803 function to hold the gate-source voltages of the transistors 501 and 801. However, it can be omitted depending on the gate capacitance of the transistors 501 and 801. Note that in FIG. 5, the wiring 504 is connected to the capacitor 503, and in FIG. 8, the wiring 504 and the wiring 805 are connected to the capacitor 803.

  Note that in FIG. 8, the source terminal of the transistor 801 is connected to the input terminal 222 of the circuit 221 to be set and is not connected to the constant potential line. Therefore, the source potential of the transistor 801 may change depending on the operating state. Therefore, the wiring 805 is preferably connected to the source terminal of the transistor 801 so that the gate-source voltage of the transistor 801 does not change even when the source potential of the transistor 801 changes. Further, the gate terminal and the drain terminal of the transistor 801 may be connected.

  Note that the transistors of the circuit to be set 221 are set so that a predetermined current can be supplied by using a signal supplied from the voltage / current supply circuit 211, that is, the current is set. The transistor of the circuit 221 to be set operates as a current source by supplying a predetermined current to another circuit or element. However, in FIGS. 5 and 8, for simplicity, other circuits and elements that supply current after the transistors (transistors 501 and 801) of the circuit to be set 221 have been set with current are not described.

  In addition, a switch is often provided in order to hold the charge of the capacitor elements 503 and 803, but in FIGS. 5 and 8, it is not shown for simplicity.

  That is, FIGS. 5 and 8 show the configuration of the circuit to be set 221 in a state where a signal is supplied from the voltage / current supply circuit 211 and the current is set for simplicity.

  9 and 10 show configuration examples of the set circuit 221 in the case of the suction type. FIG. 10 shows the case where the transistor 1001 which operates as a current source is a P-channel type, and FIG. 9 shows the case where the transistor 901 is an N-channel type, which is considered in the same manner as FIGS. I can do it. In FIG. 9, the wiring 902 is connected to the source or drain of the transistor 901. Reference numeral 903 denotes a capacitor element, and reference numeral 904 denotes a wiring connected to the capacitor element 903. In FIG. 10, the wiring 902 is connected to the source or drain of the transistor 1001. One terminal of the capacitor 1003 is connected to the wiring 904 and the gate of the transistor 1001, and the other terminal of the capacitor 1003 is connected to the wiring 1005.

  Next, the voltage / current supply circuit 211 will be described. When a current or voltage is input, the voltage / current supply circuit 211 has a function of supplying a current corresponding to the signal and supplying a precharge voltage. The precharge voltage has an optimum magnitude so that the current supplied from the voltage / current supply circuit 211 can be written quickly.

  Various examples of the voltage / current supply circuit 211 can be used, and the details thereof are described in Japanese Patent Application No. 2003-273765, so the contents thereof can be combined with the present application.

  An example is shown in FIG. In FIG. 11, the gate potential of the transistor 5101 is controlled by passing a current through an N-channel transistor 1101. That is, the gate terminal of the transistor 5101 is connected to the gate terminal of the transistor 1101, and the gate terminal of the transistor 5103 is connected to the gate terminal of the transistor 5105. In addition, the source or drain of the transistor 1101 and the source or drain of the transistor 5101 are connected by a wiring 5102. Further, the source or drain of the transistor 5103 and the source or drain of the transistor 5105 are connected by a wiring 5104. Accordingly, current corresponding to the current flowing through the transistor 1101 flows through the transistor 5101, the transistor 5103, and the transistor 5105. Here, the ratio W51 / L51 of the channel width W and the channel length L of the transistor 1101, the ratio W52 / L52 of the channel width W and the channel length L of the transistor 5101, and the ratio W53 / L53 of the channel width W and the channel length L of the transistor 5103. As a ratio W54 / L54 between the channel width W and the channel length L of the transistor 5105, (W51 / L51) = (W52 / L52) / ε and (W53 / L53) = (W54 / L54) / ζ. Then, a current ε times the current flowing through the transistor 1101 flows through the transistors 5101 and 5103. In addition, a current ζ times as large as the current flowing through the transistor 5103 flows through the transistor 5105.

  Then, the gate potential of the transistor 1101 is output to the voltage output terminal 214 via the amplifier circuit 1201. However, the present invention is not limited to this, and the amplifier circuit 1201 may be omitted when there is no need to perform impedance conversion.

  Here, the ratio W51 / L51 of the channel width W and the channel length L of the transistor 1101, the ratio W52 / L52 of the channel width W and the channel length L of the transistor 5101, and the ratio W53 / L53 of the channel width W and the channel length L of the transistor 5103. By adjusting the ratio W54 / L54 of the channel width W and the channel length L of the transistor 5105 and the ratio W21 / L21 of the channel width W and the channel length L of the transistor 901 in FIG. The signal voltage supplied from the voltage output terminal 214 is substantially equal to that when the signal current is supplied from the current output terminal 213 of the voltage / current supply circuit 211 to reach a steady state, that is, when signal writing is completed. It becomes a voltage value. That is, (W21 / L21) = (W51 / L51) × ε × ζ may be satisfied. Then, the gate-source voltage of the transistor 1101 and the gate-source voltage of the transistor 901 are substantially equal, and supplying a signal voltage from the voltage output terminal 214 is substantially equal to precharging. . Therefore, after the precharge, when a signal current is supplied from the current output terminal 213 of the voltage / current supply circuit 211, a steady state can be quickly achieved.

  Various examples of the voltage / current supply circuit 211 other than the above can be used in various configurations, and details thereof are described in Japanese Patent Application No. 2003-273765. I can do it.

  Next, a case where a current storage circuit 231 is inserted between the voltage / current supply circuit 211 and the set circuit 221 as shown in FIG. 2 will be described.

  As shown in FIG. 2, a signal current is output from the current output terminal 213 of the voltage / current supply circuit 211 to the current storage circuit 231 via the switch 203. In the current storage circuit 231, current setting is performed, and the current value is Remembered. At that time, a signal voltage is output from the voltage output terminal 214 of the voltage / current supply circuit 211 to the set circuit 221. Therefore, precharge is performed in the circuit 221 to be set. Thereafter, a signal current is output from the current storage circuit 231 to the set circuit 221, and the current is set in the set circuit 221. Note that the magnitude of the current output from the current storage circuit 231 to the set circuit 221 is proportional to the magnitude of the current output from the current output terminal 213 of the voltage / current supply circuit 211 to the current storage circuit 231. Alternatively, depending on the configuration of the current storage circuit 231, the current storage circuits 231 are approximately equal.

  In the case of FIG. 1, it is necessary to adjust which of the voltage / current supply circuit 211 and the circuit to be set 221 is the suction type and which is the discharge type. In the case of the configuration of FIG. 2, it is necessary to consider not only the type of the voltage / current supply circuit 211 and the set circuit 221 but also the type of the current storage circuit 231.

  First, the current storage circuit 231 is the same when a current is input from the current output terminal 213 of the voltage / current supply circuit 211 to the current storage circuit 231 and when a current is output from the current storage circuit 231 to the set circuit 221. Consider the case of type. For example, when the current storage circuit 231 is a discharge type, both the voltage / current supply circuit 211 and the set circuit 221 need to be a suction type. Conversely, when the current storage circuit 231 is a suction type, both the voltage / current supply circuit 211 and the set circuit 221 need to be a discharge type. That is, the voltage / current supply circuit 211 and the set circuit 221 need to be the same type.

  Next, when the current is input from the current output terminal 213 of the voltage / current supply circuit 211 to the current storage circuit 231 and when the current is output from the current storage circuit 231 to the set circuit 221, the current storage circuit 231 Consider the case of the opposite type. For example, in the case of a discharge type when input from the voltage / current supply circuit 211 to the current storage circuit 231 and a suction type when outputting current from the current storage circuit 231 to the set circuit 221, the voltage / current supply circuit 211 is a suction type. The set circuit 221 needs to be a discharge type. On the contrary, when the current is input from the voltage / current supply circuit 211 to the current storage circuit 231, the current storage circuit 231 is a suction type, and when the current is output from the current storage circuit 231 to the set circuit 221, the discharge type is The voltage / current supply circuit 211 is a discharge type, and the set circuit 221 needs to be a suction type. That is, the voltage / current supply circuit 211 and the set circuit 221 need to be reversed.

  Next, in the case of FIG. 2, the voltage / current supply circuit 211 will be described. Various examples of the voltage / current supply circuit 211 can be used, and the details thereof are described in Japanese Patent Application No. 2003-273765, so the contents thereof can be combined with the present application.

  An example is shown in FIG. In FIG. 12, the gate potentials of the P-channel transistor 1203 and the transistor 5201 are controlled by flowing current from the original signal input terminal 212 to the P-channel transistor 1203. Then, the gate-source voltage of the transistor 5201 changes, and the amount of current flowing through the transistor 5201 changes. Here, the wiring 5202 connects the transistor 5201 and the transistor 1203.

  Then, the current output from the current storage circuit 231 flows through the transistor 501 of the circuit to be set 221. The current output from the current storage circuit 231 to the set circuit 221 is κ times larger than the current input from the voltage / current supply circuit 211 to the current storage circuit 231.

  Then, the gate potential of the transistor 5201 is output to the voltage output terminal 214. An amplifier circuit 1201 such as a voltage follower circuit may be disposed between the original signal input terminal 212 and the voltage output terminal 214, or may not be disposed if it is not necessary to perform impedance conversion. .

  Here, by adjusting the ratio W81 / L81 of the channel width W and the channel length L of the transistor 5201 and the ratio W23 / L23 of the channel width W and the channel length L of the transistor 501, the voltage of the voltage / current supply circuit 211 is adjusted. The voltage value of the signal voltage supplied from the output terminal 214 is approximately equal to that when the signal current is supplied from the current storage circuit 231 to the set circuit 221 to reach a steady state, that is, when the signal writing is completed. become. That is, (W23 / L23) = κ × (W82 / L82) may be set. Then, the gate-source voltage of the transistor 5201 and the gate-source voltage of the transistor 501 are approximately equal, and supplying a signal voltage from the voltage output terminal 214 is approximately equal to precharging. . Therefore, when a signal current is supplied from the current output terminal 233 of the current storage circuit 231 after the precharge, the steady state can be quickly achieved.

  Next, the configuration of the current storage circuit 231 in FIG. 2 will be described. The current storage circuit 231 has a function of inputting a current from the storage current input terminal 232 and outputting a current having a magnitude corresponding to the input current from the storage current output terminal 233. Even when no current is input, since the signal is stored, a current having a magnitude corresponding to the input current can be output from the storage current output terminal 233. Any configuration may be used as long as the circuit has such a function.

  As an example of the current storage circuit 231, a suction type current storage circuit is shown in FIG. 13, and a discharge type current storage circuit is shown in FIG. Note that 5501 is a transistor, 5502 is a capacitor, and 5503, 5504, and 5505 are switches.

  Thus, the current storage circuit 231 can be configured by appropriately selecting the suction type or the discharge type.

  As described above, various configurations can be used for the examples of the voltage / current supply circuit 211 and the current storage circuit 231, and the details thereof are described in the Japanese Patent Application No. 2003-273765, and the contents thereof are described. And this application can be combined.

  In FIG. 2, the signal current is supplied from the current output terminal 213 to the current storage circuit 231 from the voltage / current supply circuit 211. However, the present invention is not limited to this, and a signal voltage and a signal current may be input as shown in FIG.

  Therefore, FIG. 3 shows a case where a signal voltage and a signal current are input to the current memory circuit 231.

  As shown in FIG. 3, the voltage / current supply circuit 241 receives a signal from the original signal input terminal 242. In response to the signal, the signal voltage is output from the second voltage output terminal 343 of the voltage / current supply circuit 241 to the current storage circuit 231 via the switch 303. This corresponds to a precharge operation. Thereafter, a signal current is output from the current output terminal 243 to the current storage circuit 231, current setting is performed in the current storage circuit 231, and the current value is stored. A signal voltage is output from the voltage output terminal 244 of the voltage / current supply circuit 241 to the set circuit 221. Therefore, precharge is performed in the circuit 221 to be set. Thereafter, a signal current is output from the current storage circuit 231 to the set circuit 221, and the current is set in the set circuit 221. Note that the magnitude of the current output from the current storage circuit 231 to the set circuit 221 is proportional to the magnitude of the current output from the current output terminal 243 of the voltage / current supply circuit 241 to the current storage circuit 231. Alternatively, depending on the configuration of the current storage circuit 231, the current storage circuits 231 are approximately equal.

  In FIG. 3, the voltage / current supply circuit 241 depends on whether the current storage circuit 231 and the set circuit 221 are the suction type or the discharge type, and depending on the polarity of the transistors constituting the circuit. It is necessary to adjust the output voltage value at the voltage output terminal 244 and the second voltage output terminal 343.

  In other words, the voltage output from the voltage output terminal 244 of the voltage / current supply circuit 241 is sized so that the precharge operation for the set circuit 221 is performed, and is output from the second voltage output terminal 343 of the voltage / current supply circuit 241. The voltage of the current storage circuit 231 is set to such a magnitude that the precharge operation is performed.

  As described above, the magnitude of each voltage is adjusted by adjusting the current value flowing through each transistor, the polarity of the transistor, the size of the transistor, whether it is a suction type or a discharge type, etc. Can be generated.

  Details are described in Japanese Patent Application No. 2003-273765, so that the contents thereof can be combined with the present application.

  Next, the case where the current storage circuit 231 is inserted between the voltage / current supply circuit 211 and the set circuit 221 has been described with reference to FIG. As a result, the signal current is temporarily stored and then input to the set circuit 221. Therefore, similarly, a voltage storage circuit 251 may be inserted between the voltage / current supply circuit 211 and the set circuit 221. FIG. 4 shows a configuration in which a voltage storage circuit 251 is arranged with respect to the configuration of FIG. In this figure, 204 is a switch, 252 is an input terminal, and 253 is an output terminal.

  However, the present invention is not limited to this, and the voltage storage circuit 251 may be arranged in the configuration of FIG. Similarly, in the configuration of FIG. 3, the voltage storage circuit 251 may be disposed between the voltage / current supply circuit 241 and the current storage circuit 231.

  For the example of the voltage storage circuit 251, various structures can be used. The voltage storage circuit 251 has a function of inputting a voltage and outputting a voltage having a magnitude corresponding to the input voltage. Even when no voltage is input, since the signal is stored, a voltage having a magnitude corresponding to the input voltage can be output. Any configuration may be used as long as the circuit has such a function. An example is shown in FIG. Since these details are described in Japanese Patent Application No. 2003-273765, the contents thereof can be combined with the present application. In FIG. 15, a capacitor 1501 and an amplifier circuit 1502 are arranged as elements for storing voltage values. Note that the amplifier circuit 1502 is a circuit that outputs a potential substantially equal to the input potential, and is preferably a voltage follower circuit or the like. However, the present invention is not limited to this, and a function for converting impedance may be performed. Note that when there is no need to perform impedance conversion, the amplifier circuit 1502 may be omitted.

  So far, a circuit for supplying video signal voltage and video signal current has been described. Then, next, a configuration example and a corresponding relationship when a circuit for supplying a video signal voltage and a video signal current is applied to a display device will be described.

  First, an example of the basic configuration is shown in FIG. A plurality of pixels 5309aa and 5309ab are connected to the signal line 5302a. The signal line 5302a is connected to the voltage storage circuit 251 through the switch 201 and is connected to the current storage circuit 231 through the switch 202. The voltage / current supply circuit 211 has a voltage output terminal 214 connected to the voltage storage circuit 251 via the switch 204, and a current output terminal 213 connected to the current storage circuit 231. Then, a signal is input from the original signal input terminal 212 of the voltage / current supply circuit 211.

  The configuration in FIG. 16 corresponds to a configuration to which the configuration in FIG. 4 is applied. 4 corresponds to the voltage / current supply circuit 211 in FIG. 16, the current storage circuit 231 in FIG. 4 corresponds to the current storage circuit 231 in FIG. 16, and the voltage storage circuit in FIG. 251 corresponds to the voltage storage circuit 251 in FIG. 16, and the set circuit 221 in FIG. 4 corresponds to the pixels 5309aa to 5309ab in FIG.

  Next, the operation method of FIG. 16 will be described. As shown in FIG. 17, a signal is input from the original signal input terminal 212, and a current is supplied from the current output terminal 213 to the current storage circuit 231. At that time, a video signal voltage is supplied to the signal line 5302a and the pixels 5309aa to 5309ab through the voltage storage circuit 251. This video signal voltage corresponds to a precharge voltage.

  Next, the supply of the signal from the voltage / current supply circuit 211 is stopped. Then, a video signal current is supplied from the current storage circuit 231 to the signal line 5302a. From the voltage storage circuit 251, the video signal voltage is continuously supplied to the signal line 5302a. Then, as shown in FIG. 19, the supply of the video signal voltage from the voltage storage circuit 251 is stopped, and the video signal current continues to be supplied to the signal line 5302a. Through the above operation, a video signal voltage is supplied to the pixel (but may not be supplied), and then a video signal current is supplied. Therefore, a steady state can be quickly obtained, and the influence of transistor variation can be reduced.

  16 to 19, the supply timing of the video signal voltage to the signal line 5302a is controlled using the wirings 1601 and 1602, but the present invention is not limited to this. For example, in the configuration of FIG. 20, after supplying the video signal voltage as shown in FIG. 21, the video signal current may be supplied as shown in FIG. Thereby, the number of wirings can be reduced. In this case, the voltage storage circuit 251 does not need to store the signal voltage. Therefore, the voltage memory circuit 251 only needs to have a function of supplying a sufficiently large signal, that is, a function of converting impedance. Alternatively, as shown in FIG. 23, the voltage storage circuit 251 may be deleted if the video signal voltage supplied from the voltage / current supply circuit 211 is sufficiently supplied. This case corresponds to the case where the configuration of FIG. 2 is applied. In FIG. 20, reference numeral 2001 denotes a wiring.

  Next, FIG. 24 shows a case where the configuration of FIG. 1 is applied. After the video signal voltage is supplied from the voltage / current supply circuit 211 to perform precharging, the video signal current is supplied. In FIG. 24, reference numeral 2401 denotes a wiring.

  Next, FIG. 25 shows a case where the configuration of FIG. 3 is applied. In this case, even when a current is supplied from the voltage / current supply circuit 241 to the current storage circuit 231, a video signal voltage is supplied from the second voltage output terminal 343 to perform precharging. Note that, as in FIG. 20 and FIG. 23, the number of wirings can be reduced or the voltage storage circuit 251 can be deleted.

  Next, an example of a circuit configuration of the current storage circuit 231 in FIGS. This is the same configuration as the current storage circuit 231 shown in FIGS. First, FIG. 26 shows a diagram in which the current source circuit portion is extracted from FIG. 16 and FIG. As shown in FIG. 26, the current source circuit 5307 includes at least a current input terminal 2602, a timing control terminal 2603, and a current output terminal 2601. Here, a switch 5305 is connected to the current output terminal 2601.

  Next, FIG. 27 shows a specific circuit configuration example of FIG. The switches 2703 and 2704 are turned on, the switch 2705 is turned off, and current is input to the current source transistor 2701 and the storage capacitor 2702 through the current input terminal 2602. When the input of current is completed, that is, when a steady state is reached, an appropriate voltage is stored in the storage capacitor 2702. Thereby, even if the current characteristics of the current source transistor vary, the influence can be reduced. Next, the switches 2703 and 2704 are turned off and the switch 2705 is turned on. Then, current can be output through the current output terminal 2601.

  In the case of FIG. 27, the video current signal input to the current source circuit 5307 through the current input terminal 2602 and the video current signal output from the current source circuit 5307 through the current output terminal 2601 are The size is almost equal. This depends on the circuit configuration. That is, since the transistor to which current is input through the current input terminal 2602 and the transistor that outputs current through the current output terminal 2601 are the same, the magnitudes of the currents are approximately equal.

  Therefore, the current magnitude can be changed by changing the ratio of the channel width W to the channel length L in the current source transistor 2801 and the mirror transistor 2806 in the configuration shown in FIG. In this case, the magnitude of the video current signal input to the current source circuit 5307 through the current input terminal 2602 and the video current signal output from the current source circuit 5307 through the current output terminal 2601 is as follows: Proportional relationship. In FIG. 28, reference numeral 2802 denotes a capacitor, and 2803 and 2804 denote switches.

  Similarly, with the configuration shown in FIG. 29, it is possible to control whether the current source transistor 2901 and the multi-transistor 2906 operate as multi-gate transistors by controlling the switch 2907. In this case, the video current signal input to the current source circuit 5307 through the current input terminal 2602 and the video current signal output from the current source circuit 5307 through the current output terminal 2601 according to the ON / OFF timing of the switch 2907. In the case of, the size may be proportional or may be generally pleasing. In FIG. 29, reference numeral 2902 denotes a capacitor, and 2903, 2904, and 2905 denote switches.

  Note that the operation of the current source circuit as shown in FIG. 29 is described in Japanese Patent Application Nos. 2002-380252 and 2003-055018, and the contents thereof can be combined with the present application. .

  In FIGS. 27 to 29, both the current flowing through the current input terminal 2602 and the current flowing through the current output terminal 2601 flow toward the current source circuit, but the present invention is not limited to this. A current may flow in the opposite direction between the current input terminal 2602 and the current output terminal 2601.

  In FIGS. 27 to 29, the polarity of the transistor operating as a current source is an N-channel type, but is not limited thereto. As an example, FIG. 30 shows a case where the transistor polarity is P-channel type with respect to the configuration of FIG. 28 to 29, if the same concept is applied, the polarity of the transistor can be changed.

  In FIGS. 27 to 30, the current flows to the current source circuit, but the present invention is not limited to this. Even when the direction of the current is changed, it can be easily deformed. For example, by reversing the polarity of a transistor operating as a current source, it is possible to cope with the circuit without changing the connection relation of the circuit. In FIG. 30, 3001 is a transistor, 3002 is a capacitor, and 3003, 3004, and 3005 are switches.

  In addition, although the current source circuit of various structures was shown, it is not limited to this. With respect to the basic configuration, the number, polarity and arrangement of the current source transistors, the direction of current flow, and the like, further configurations can be used by combining the configurations or combining the concepts in the configurations. That is, any configuration can be used as long as it operates as a current source circuit.

  Moreover, it is possible to easily change the arrangement and number of switches in each part and the connection relations associated therewith. In other words, any number of switches may be provided as long as they operate normally, and a plurality of switches may be combined into one, or a connection relationship may be modified to add or delete switches.

  Regarding the configuration of the current source circuit, International Publication No. 03/038793, International Publication No. 03/038794, International Publication No. 03/038795, International Publication No. 03/038796, International Publication No. 03 / 038797 pamphlet, the contents of which can be applied to the present invention or combined with the present invention.

(Embodiment 2)
In the first embodiment, the case where circuits such as the voltage / current supply circuit and the voltage storage circuit are connected to one signal line, that is, the case of one column is described. If these circuits are arranged in a plurality of columns, the pixels are arranged two-dimensionally. A plurality of voltage / current supply circuits 211 are also arranged.

  Therefore, when a plurality of voltage / current supply circuits 211 are arranged, it is necessary to supply a signal to the original signal input terminal 212 of each voltage / current supply circuit. Therefore, a drive circuit for controlling the supply of signals to the original signal input terminal 212 of each voltage / current supply circuit will be described.

  First, FIG. 31 shows a drive circuit in the most basic case. Here, for the sake of simplicity, a case where three columns of voltage / current supply circuits are arranged will be described. Voltage / current supply circuits 211a to 211c are connected to the original signal supply line 3104 through switches 3101a to 3101c. Then, the switches 3101a to 3101c are sequentially selected by the driving circuit 3103. As a result, the video signals supplied from the original signal current source circuit 3102 are sequentially supplied to the voltage / current supply circuit.

  However, in this case, after the switch is selected and the video signal is supplied from the original signal current source circuit 3102 to the voltage / current supply circuit, the supply of the video signal is moved to another voltage / current supply circuit. End up. Therefore, in each of the voltage / current supply circuits 211a to 211c, even after the supply of the signal to the original signal input terminals 212a to 212c is stopped, the video signal current and video from the current output terminals 213a to 213c and the voltage output terminals 214a to 214c. It is necessary to continue supplying the signal voltage. In order to realize this, each of the voltage / current supply circuits 211a to 211c needs a function of storing a signal.

  Therefore, an example of a voltage / current supply circuit modified to have a function of storing signals will be described. FIG. 32 shows a configuration when a signal storage function is added to the voltage / current supply circuit of FIG. A capacitor 3202 is added, and a switch 3201 prevents a signal held in the capacitor 3202 from leaking.

  Similarly, FIGS. 33 to 39 show configurations when a signal storage function is added to the voltage / current supply circuit. In FIG. 33, reference numeral 5601 denotes a transistor. In FIG. 35, reference numeral 5701 denotes a transistor which is connected to the transistor 5101 through a wiring 5102. 36, reference numerals 701 and 702 denote transistors, reference numeral 703 denotes wirings connected to the transistor 702, reference numerals 1201a and 1201b denote amplifier circuits, and reference numerals 3601 denote switches. In FIG. 37, 3701 is a switch, 3702 is a capacitor, 5803, 5806, 5808, and 5809 are transistors, and 5804 and 5807 are wirings. In FIG. 38, 3801 is a switch, 3802 is a capacitor, 5901, 5903 and 5905 are transistors, and 5902 and 5904 are wirings. In FIG. 39, 3901 is a switch and 3902 is a capacitor.

  For other voltage / current supply circuits, a storage means such as a capacitive element is provided at a position where a video signal current or a video signal voltage can be continuously supplied from the current output terminal 243 or the voltage output terminal 244. A switch for keeping the memory state may be arranged.

  Note that a capacitor or the like can be omitted by using a gate capacitance of a transistor or the like.

  In addition, regarding a voltage / current supply circuit that has a function to store signals, when a signal is input from the original signal input terminal, it is not necessary to output a signal from the current output terminal or the voltage output terminal at the same time. Can take other configurations. An example in that case is shown in FIG. When a signal is input from the original signal input terminal 212, the switches 4001 and 4003 are turned on and the switch 4002 is turned off. Then, the signal is stored in the capacitor 4004. When a current is output from the current output terminal 213, the switches 4001 and 4003 are turned off and the switch 4002 is turned on.

  In this manner, the same transistor 5201 is used when a signal is input from the original signal input terminal 212 and when a current is output from the current output terminal 213, so that the influence of variations in transistor current characteristics is eliminated. I can do it.

  Alternatively, when the voltage / current supply circuit does not have a signal storage function, it may be as shown in FIG. That is, while the voltage / current supply circuit continues to output a signal, the signal may be continuously input from a circuit having a signal storage function. Thus, when signals are sequentially supplied from the original signal current source circuit 3102 to the current source circuits 4131a to 4131c, the previously supplied and stored signals are simultaneously supplied to the voltage / current supply circuits 211a to 211c. ing.

  Note that the structure of the drive circuit is not limited to that shown in FIG. For example, as shown in FIG. 42, a plurality of original signal current source circuits 3102a, 3102b are connected to the original signal supply lines 3104a, 3104b, and a plurality of voltage / current supply circuits 211a are connected via the switches 3101aa, 3101ab, 3101ba. A signal may be input to ˜211c.

  Alternatively, as shown in FIG. 43, a plurality of original signal current source circuits 3102c and 3102d are connected to the original signal supply lines 3104c and 3104d, and switches 3101da, 3101db, 3101ea and 3101eb are connected to the switches 3101da, 3101db and 3101ea. The signal current may be input to the voltage / current supply circuits 211a and 211b by adding the currents flowing through 3101eb.

  Alternatively, as shown in FIG. 44, a signal may be input to the voltage / current supply circuits 211a to 211c using a voltage / current supply circuit 211z having an original signal input terminal 212z as the original signal current source circuit. In this case, the voltage / current supply circuit 211z first outputs a precharge voltage from the current output terminal 213z, and then outputs a signal current. Therefore, a signal can be written quickly. Reference numerals 4401 and 4402 denote switches.

  Next, FIG. 45 shows an example of a configuration when FIG. 31 and FIG. 16 are combined. In this figure, 201a, 201b, 202a and 202b are switches, and 5309aa, 5309ab, 5309ba and 5309bb are pixels. Reference numerals 5302a and 5302b denote signal lines, 251a and 251b denote voltage storage circuits, and 231a and 231b denote current storage circuits.

  Further, structural examples described at the transistor level are shown in FIGS. 46 to 49 show circuit diagrams for one column.

  In FIG. 46, a current substantially equal to the video signal current supplied from the original signal current source circuit 3102 is input to the transistors 4601a and 4601b in the pixel. Therefore, it is desirable that the W / L of the transistor 4605 and the W / L of the transistors 4601a and 4601b be substantially equal. Accordingly, the precharge voltage output from the voltage follower circuit 4606 to the pixel can be set to an appropriate level. Here, reference numerals 4602 and 4604 are wirings, 4603 is a transistor, 4607 is an amplifier circuit, and 4608 and 4609 are switches.

  47 corresponds to a circuit in which the voltage follower circuit 4606 in FIG. 46 is omitted. That is, the circuit diagram corresponds to FIG.

  FIG. 48 corresponds to the case where the current storage circuit 231 in FIG. 16 is in a current mirror format. Therefore, the video signal current supplied from the original signal current source circuit 3102 and the magnitude of the signal current input to the transistors 4601a and 4601b in the pixel are not necessarily the same. Therefore, here, assuming that W / L of the transistor 4803 is A times that of the transistor 4804, it is desirable that W / L of the transistor 4605 be A times that of the transistors 4601a and 4601b. Accordingly, the precharge voltage output from the voltage follower circuit 4606 to the pixel can be set to an appropriate level.

  FIG. 49 corresponds to the case where the current source portions in the voltage / current supply circuits 211a to 211b in FIG. 45 are in a current mirror format. Therefore, the video signal current supplied from the original signal current source circuit 3102 and the magnitude of the signal current input to the transistors 4601a and 4601b in the pixel are not necessarily the same. Note that a current substantially equal to the signal current output from the transistor 4904 is input to the transistors 4601a and 4601b in the pixel. Therefore, it is desirable that the W / L of the transistor 4904 and the W / L of the transistors 4601a and 4601b be substantially equal. Accordingly, the precharge voltage output from the voltage follower circuit 4606 to the pixel can be set to an appropriate level.

  Note that the circuit configuration is not limited to this, and various configurations can be adopted by combining each circuit.

  As for the configuration of the pixel, any configuration may be used as long as at least current is input. Further, the load disposed on the pixel is not limited to the EL element. An element such as a resistor, a transistor, an EL element, another light emitting element, a current source circuit composed of a transistor, a capacitor, a switch, and the like, a wiring to which an arbitrary circuit is connected, or a signal line, a signal line, It may be a connected pixel. The pixel may include an EL element, an element used in an FED, or an element driven by passing current.

  In the various configurations described so far, the switch is arranged in each part, but the arrangement place is not limited to the place already described. A switch can be arranged at an arbitrary place as long as it operates normally.

  The switch may be an electrical switch or a mechanical switch. Anything that can control the current flow is acceptable. It may be a transistor, a diode, or a logic circuit combining them. Therefore, when a transistor is used as a switch, the transistor operates as a mere switch, and thus the polarity (conductivity type) of the transistor is not particularly limited. However, when it is desirable that the off-state current is small, it is desirable to use a transistor having a polarity with a small off-state current. As a transistor with low off-state current, there is a transistor provided with an LDD region. In addition, the n-channel type is used when the source terminal potential of a transistor that operates as a switch is close to a low potential side power supply (Vss, Vgnd, 0 V, etc.), while the source terminal potential is a high potential. When operating in a state close to a side power supply (Vdd or the like), it is desirable to use a p-channel type. This is because the absolute value of the voltage between the gate and the source can be increased, so that it can easily operate as a switch. Note that a CMOS switch may be formed using both an n-channel type and a p-channel type.

(Embodiment 3)
As an electronic device using the present invention, a video camera, a digital camera, a goggle type display (head mounted display), a navigation system, a sound reproduction device (car audio, audio component, etc.), a notebook type personal computer, a game device, a portable information terminal (Mobile computer, mobile phone, portable game machine, electronic book, or the like), an image playback apparatus equipped with a recording medium (specifically, a recording medium such as a digital versatile disc (DVD) can be played back and the image can be displayed. And a device equipped with a display). Specific examples of these electronic devices are shown in FIGS.

  FIG. 50A illustrates a light-emitting device, which includes a housing 13001, a support base 13002, a display portion 13003, a speaker portion 13004, a video input terminal 13005, and the like. The present invention can be used for an electric circuit included in the display portion 13003. Further, according to the present invention, the light-emitting device shown in FIG. 50A is completed. Since the light-emitting device is a self-luminous type, a backlight is not necessary and a display portion thinner than a liquid crystal display can be obtained. Note that the light emitting device includes all display devices for displaying information such as for personal computers, for receiving TV broadcasts, and for displaying advertisements.

  FIG. 50B shows a digital still camera, which includes a main body 13101, a display portion 13102, an image receiving portion 13103, operation keys 13104, an external connection port 13105, a shutter 13106, and the like. The present invention can be used for an electric circuit included in the display portion 13102. Further, according to the present invention, the digital still camera shown in FIG. 50B is completed.

  FIG. 50C illustrates a personal computer, which includes a main body 13201, a housing 13202, a display portion 13203, a keyboard 13204, an external connection port 13205, a pointing mouse 13206, and the like. The present invention can be used for an electric circuit included in the display portion 13203. Further, the personal computer shown in FIG. 50C is completed according to the present invention.

  FIG. 50D illustrates a mobile computer, which includes a main body 13301, a display portion 13302, a switch 13303, operation keys 13304, an infrared port 13305, and the like. The present invention can be used for an electric circuit included in the display portion 13302. Further, according to the present invention, the mobile computer shown in FIG. 50D is completed.

  FIG. 50E shows a portable image playback device (specifically, a DVD playback device) provided with a recording medium, which includes a main body 13401, a housing 13402, a display portion A13403, a display portion B13404, and a recording medium (DVD, etc.). A reading unit 13405, operation keys 13406, a speaker unit 13407, and the like are included. Although the display portion A 13403 mainly displays image information and the display portion B 13404 mainly displays character information, the present invention can be used for an electric circuit constituting the display portions A, B 13403, and 13404. Note that an image reproducing device provided with a recording medium includes a home game machine and the like. Further, according to the present invention, the DVD reproducing apparatus shown in FIG. 50 (E) is completed.

  FIG. 50F illustrates a goggle type display (head mounted display), which includes a main body 13501, a display portion 13502, and an arm portion 13503. The present invention can be used for an electric circuit included in the display portion 13502. Further, the goggle type display shown in FIG. 50F is completed by the present invention.

  FIG. 50G illustrates a video camera, which includes a main body 13601, a display portion 13602, a housing 13603, an external connection port 13604, a remote control reception portion 13605, an image receiving portion 13606, a battery 13607, an audio input portion 13608, operation keys 13609, and an eyepiece Part 13610 and the like. The present invention can be used for an electric circuit included in the display portion 13602. Further, according to the present invention, the video camera shown in FIG. 50G is completed.

  FIG. 50H illustrates a cellular phone, which includes a main body 13701, a housing 13702, a display portion 13703, an audio input portion 13704, an audio output portion 13705, operation keys 13706, an external connection port 13707, an antenna 13708, and the like. The present invention can be used for an electric circuit included in the display portion 13703. Note that the display portion 13703 can suppress current consumption of the mobile phone by displaying white characters on a black background. In addition, the mobile phone shown in FIG. 50H is completed by the present invention.

  If the emission luminance of the luminescent material is increased in the future, the light including the output image information can be enlarged and projected by a lens or the like to be used for a front type or rear type projector.

  In addition, the electronic devices often display information distributed through electronic communication lines such as the Internet and CATV (cable television), and in particular, opportunities to display moving image information are increasing. Since the response speed of the light emitting material is very high, the light emitting device is preferable for displaying moving images.

  Further, since the light emitting part consumes power in the light emitting device, it is desirable to display information so that the light emitting part is minimized. Therefore, when a light emitting device is used for a display unit mainly including character information, such as a portable information terminal, particularly a mobile phone or a sound reproduction device, it is driven so that character information is formed by the light emitting part with the non-light emitting part as the background. It is desirable to do.

  As described above, the applicable range of the present invention is so wide that the present invention can be used for electronic devices in various fields. In addition, the electronic device of this embodiment may use the semiconductor device having any structure described in Embodiments 1 and 2.

6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. FIG. 10 illustrates a structure of a conventional pixel. FIG. 10 is a diagram illustrating an operation of a conventional pixel. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 8A and 8B illustrate operation of a semiconductor device of the present invention. 8A and 8B illustrate operation of a semiconductor device of the present invention. 8A and 8B illustrate operation of a semiconductor device of the present invention. 8A and 8B illustrate operation of a semiconductor device of the present invention. 8A and 8B illustrate operation of a semiconductor device of the present invention. 8A and 8B illustrate operation of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 6A and 6B illustrate a structure of a semiconductor device of the present invention. 1 is a diagram of an electronic device to which the present invention is applied.

Claims (8)

A voltage-current supply circuit, a current storage circuit, and a pixel;
The voltage / current supply circuit has means for supplying a current to the current storage circuit, and means for supplying a voltage to the pixel,
The semiconductor device according to claim 1, wherein the current storage circuit includes means for supplying a current to the pixel. In claim 1,
The semiconductor device according to claim 1, wherein the voltage / current supply circuit includes means for supplying a voltage to the pixel through a voltage storage circuit. In claim 1 or claim 2,
The semiconductor device characterized in that the voltage supplied to the pixel by the voltage / current supply circuit is a precharge voltage to the pixel. In any one of Claims 1 thru | or 3,
A display device comprising the semiconductor device. In claim 4,
An electronic apparatus comprising the display device. The voltage / current supply circuit supplies current to the current storage circuit,
The voltage / current supply circuit supplies a voltage to the pixel,
The method of driving a semiconductor device, wherein the current storage circuit supplies a current to the pixel. In claim 6,
The method of driving a semiconductor device, wherein the voltage / current circuit supplies a voltage to the pixel through a voltage storage circuit. In claim 6 or claim 7,
The method of driving a semiconductor device, wherein the voltage / current supply circuit supplies a precharge voltage to the pixel.

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