JP2010092062A - Electrooptical device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electronic circuit which can be constructed using a simple circuit, can AC drive an element without the use of special alternating current power supply, prolongs the lifetime of the element and lowers the production cost, and to provide a drive method of the electronic circuit, an electrooptical device, a driving method of the electrooptical device, and an electronic apparatus. <P>SOLUTION: Each unit circuit has a transistor Qs, an organic EL element 31 connected to it, and a holding capacitor Cp for reverse bias. A terminal b of the holding capacitor Cp is connected to a scanning line (one of Y1-Ym), to which the gate of the corresponding transistor Qs is also connected. Signals sequentially applied to the scanning line contain voltages of GND, Vg1 and -Vg2, and the organic EL element 31 is AC driven by the voltages of these 3 levels. When the transistor Qs is brought to an ON-state, in each selection period wherein the voltage Vg1 is applied to the scanning line, the organic EL element is biased in the forward direction, and emits a light. When the voltage -Vg2 is applied to the scanning line, the organic EL element is biased in the reverse direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electronic circuit, an electronic circuit driving method, an electro-optical device, an electro-optical device driving method, and an electronic apparatus.

  In recent years, a display device using an organic EL element as an electro-optical device has attracted attention as being superior to other devices in terms of low power consumption, a high viewing angle, and a high contrast ratio. A display device using an organic EL element has a problem that the life of the organic EL element is short. In order to solve such a problem, a conventional technique in which an organic EL element is AC driven is known (for example, Patent Document 1). In this display device, a switching TFT, a capacitor, a current control TFT, an element having a rectifying characteristic, and an AC power source are provided in each of a plurality of pixels, and a forward direction is applied from the AC power source to an element having the rectifying characteristic. By applying a voltage to, a reverse bias is applied to the organic EL element.

JP 2002-358048 A

  By the way, in the above prior art, it is necessary to provide each of a plurality of pixels with two TFTs, a capacitor, an element having a rectifying characteristic, a scanning line, a data line, and a power supply line, and further a special AC power source is required. Met. Because of such a configuration, in the conventional technique, many components (elements, wirings, etc.) are packed in one pixel, and the aperture ratio is difficult to increase. Therefore, strong light emission intensity is required to make the organic EL element emit light with a limited opening. For this purpose, a large amount of current needs to flow through the organic EL element. Then, heat generation of the organic EL element is generated and the life thereof is reduced. In addition, in the case of a complicated configuration in which many components are packed in one pixel as in the above prior art, the yield deteriorates due to the influence of dust and the like during the manufacturing process, and it is difficult to provide an inexpensive display device. It was.

  Further, the AC power supply is connected between the cathode of the organic EL element and the power supply line in each pixel, and a special power supply having a large power supply capability is required to drive the entire display screen with AC.

  The present invention has been made in view of the above-described conventional problems, and the object thereof can be configured with a simple circuit, the element can be AC driven without using a special AC power source, and the length of the element can be increased. It is an object of the present invention to provide an electronic circuit, an electronic circuit driving method, an electro-optical device, an electro-optical device driving method, and an electronic apparatus that achieve a lifetime and a reduction in manufacturing cost.

  The electro-optical device according to the present invention is an electronic circuit including a switching element. The switching element includes a control terminal connected to the first wiring, a first terminal connected to the second wiring, and an electronic element. And a second terminal connected to the capacitor, and when a voltage is applied to the control terminal and the switching element is turned on, a data signal supplied from the second wiring is the first and When the voltage written in the electronic element through the second terminal and having a polarity opposite to that of the voltage applied to the control terminal is applied to the capacitive element, the electronic element is biased in the reverse direction. The gist.

  According to this, (1) when a voltage is applied to the control terminal of the switching element and the switching element is turned on, the data signal supplied from the second wiring is connected to the first terminal and the second terminal of the switching element. It is written in the electronic element through the terminal. At this time, the electronic element is biased in the forward direction. When a voltage having a polarity opposite to that of the voltage is applied to the other terminal of the capacitive element, the electronic element is biased in the reverse direction. Since the electronic element is thus AC driven, the life of the electronic element can be extended. (2) Since only one transistor for the switching element is required and no special AC power source or power supply line for AC driving the electronic element is required, a circuit with a simple configuration can be realized with a small number of components. This can reduce the manufacturing cost. In addition, since the circuit configuration is simplified, it is less susceptible to dust during the manufacturing process, and the yield is improved. This can also reduce the manufacturing cost. Therefore, it can be configured with a simple circuit, the element can be AC driven without using a special AC power source, and the life of the element can be extended and the manufacturing cost can be reduced.

In this electronic circuit, the electronic element is a current-driven light emitting element.
According to this, when applied to an electro-optical device such as an EL display device using a light emitting element such as an organic EL element for each unit circuit of a plurality of pixels arranged in a matrix, each unit circuit is a transistor for a switching element. Since it can be configured by a simple circuit including one, a low-cost electro-optical device can be realized. At the same time, as in the prior art, many components such as a plurality of transistors and wirings are not packed in one pixel, so that an effective light emitting area of one pixel increases and an aperture ratio increases. As a result, the current flowing through the light emitting element can be reduced to reduce the light emission intensity of the light emitting element per unit area, and the amount of heat generated by the light emitting element can be reduced to keep the element temperature low. Thereby, the lifetime of the light emitting element can be further extended.

  In this electronic circuit, when the switching element is turned on, a charge corresponding to the voltage of the data signal is accumulated in the capacitor element, and a current corresponding to the data signal flows to the light emitting element through the switching element. When the light emitting element emits light and the switching element is turned off, the electric charge accumulated in the capacitor element is discharged through the light emitting element, current flows through the light emitting element, and the light emitting element emits light.

  According to this, when the switching element is turned on, a current corresponding to the data signal flows to the light emitting element through the switching element, so that the light emitting element can emit light with brightness according to the current of the data signal. In addition, when the switching element is turned from the on state to the off state, the charge accumulated in the capacitor element is discharged through the light emitting element, current flows through the light emitting element, and the light emitting element emits light. Therefore, the light emitting element can emit light even after the switching element is turned off until the switching element is biased in the reverse direction.

  In the driving method of the electronic circuit including the switching element according to the present invention, the switching element includes a control terminal connected to the first wiring, a first terminal connected to the second wiring, and the electronic element and the capacitor. A second terminal connected to the device, and a voltage is applied to the control terminal to set the switching device to an on state, and a data signal supplied from the second wiring is transmitted to the first and second terminals. A first step of writing to the electronic element through two terminals, and a voltage having a polarity opposite to the voltage applied to the control terminal is applied to the capacitive element to bias the electronic element in a reverse direction. It is a summary to include two steps.

According to this, it is possible to extend the life of the electronic element and reduce the manufacturing cost.
The electro-optical device according to the aspect of the invention includes a plurality of scanning lines, a plurality of data lines, and a plurality of unit circuits arranged corresponding to intersections of the scanning lines and the data lines. Each has a control terminal connected to a corresponding scanning line among the plurality of scanning lines, a first terminal connected to a corresponding data line among the plurality of data lines, and a second terminal. A switching element; a light emitting element connected to the second terminal; and a capacitive element having one terminal connected to the second terminal, the other terminal of the capacitive element being a corresponding one of the switching elements The gist is that the signal connected to the same scanning line as the control terminal and sequentially applied to the plurality of scanning lines includes a three-level voltage, and the light emitting element is AC driven by the signal. To do.

  According to this, (1) one of the three level voltages (Vg1) is sequentially applied to the plurality of scanning lines, whereby the plurality of scanning lines are sequentially selected. When each switching element corresponding to the scanning line to be selected is turned on during each selection period, a current corresponding to the data signal supplied from the data line flows through the light emitting element, and the light emitting element emits light. At this time, the light emitting element is biased in the forward direction. In addition, among the three levels of voltage, a voltage (-Vg2) having a polarity opposite to that of the one voltage is sequentially applied to the plurality of scanning lines, so that the corresponding light emitting elements are biased in the reverse direction. The flash stops. In this way, the light emitting element of each unit circuit is AC driven, so that the life of the light emitting element can be extended. (2) When applied to an electro-optical device such as an EL display device, the transistor of each unit circuit is only one transistor for the switching element, and no special AC power source or power supply line for AC driving the light emitting element is required. become. For this reason, since many components are not packed in one pixel like the above-mentioned prior art, the effective light emission area of one pixel increases and the aperture ratio increases. As a result, the current flowing through the light emitting element can be reduced, the light emission intensity of the light emitting element per unit area can be reduced, the amount of heat generated by the light emitting element can be reduced, and the element temperature can be kept low. Life can be extended. (3) The number of transistors in each unit circuit is only one for the switching element, and a special AC power source and power supply line for AC driving the light emitting element are not required, so that the manufacturing cost can be reduced. Further, since the configuration of each unit circuit is simplified, it is less susceptible to dust during the manufacturing process, and the yield is improved. This can also reduce the manufacturing cost. Therefore, it can be configured with a simple circuit, the element can be AC driven without using a special AC power supply, the life of the element can be extended, the manufacturing cost can be reduced, and a low-cost electro-optical device can be realized. it can. (4) The light emitting element of each unit circuit can be AC driven for each row of unit circuits corresponding to each of the plurality of scanning lines. (5) In each selection period in which one of three levels of voltages is sequentially applied to a plurality of scanning lines, when the switching element is turned on, the light emitting element emits light and the data signal supplied via the switching element A charge corresponding to the voltage is accumulated in the capacitor. After that, when the switching element is turned off, the charge accumulated in the capacitor element is discharged through the light emitting element, current flows through the light emitting element, and the light emitting element emits light. Therefore, the light emission period after the switching element is turned off is appropriately adjusted by changing the timing of applying the reverse polarity voltage to the other terminal of the capacitor element and biasing the light emitting element in the reverse direction. be able to.

  The “three-level voltage” mentioned here is, for example, 3 of a reference voltage (GND), a first voltage (Vg1) higher than the reference voltage, and a second voltage (−Vg2) lower than the reference voltage. It is a kind of voltage.

  The electro-optical device according to the aspect of the invention includes a plurality of scanning lines, a plurality of data lines, and a plurality of unit circuits arranged corresponding to intersections of the scanning lines and the data lines. Each has a control terminal connected to a corresponding scanning line among the plurality of scanning lines, a first terminal connected to a corresponding data line among the plurality of data lines, and a second terminal. A switching element; a light emitting element connected to the second terminal; and a capacitive element having one terminal connected to the second terminal, the other terminal of the capacitive element being a corresponding one of the switching elements A signal connected to the preceding scanning line selected before the scanning line to which the control terminal is connected and applied in order to the plurality of scanning lines includes a three-level voltage. AC driven And summarized in that the sea urchin configuration.

  According to this, a simple circuit can be configured, the element can be AC driven without using a special AC power source, the life of the element can be extended, and the manufacturing cost can be reduced. A device can be realized. In addition, the light emitting element of each unit circuit can be AC driven for each unit circuit of one row corresponding to each of the plurality of scanning lines. Furthermore, the light emission period after the switching element is turned off can be appropriately adjusted.

  The electro-optical device according to the aspect of the invention includes a plurality of scanning lines, a plurality of data lines, and a plurality of unit circuits arranged corresponding to intersections of the scanning lines and the data lines. Each has a control terminal connected to a corresponding scanning line among the plurality of scanning lines, a first terminal connected to a corresponding data line among the plurality of data lines, and a second terminal. A switching element; a light emitting element connected to the second terminal; and a capacitive element having one terminal connected to the second terminal, the other terminal of the capacitive element being connected to a capacitive line; The gist of the present invention is that the signals sequentially applied to the plurality of scanning lines and the capacitor lines include two levels of voltages, respectively, and the light emitting element is AC driven by the signals.

  According to this, a simple circuit can be configured, the element can be AC driven without using a special AC power source, the life of the element can be extended, and the manufacturing cost can be reduced. A device can be realized. In addition, by changing the timing of applying the reverse polarity voltage to the other terminal of the capacitor element to bias the light emitting element in the reverse direction, the light emission period after the switching element is turned off is appropriately adjusted. be able to.

In this electro-optical device, the capacitor line is provided independently for each unit circuit of one row corresponding to each of the plurality of scanning lines.
According to this, the light emitting element of each unit circuit can be AC driven for each row of unit circuits corresponding to each of the plurality of scanning lines.

  The electro-optical device driving method according to the present invention includes a plurality of scanning lines, a plurality of data lines, and a plurality of unit circuits arranged corresponding to intersections of the scanning lines and the data lines. Each of the unit circuits includes a control terminal connected to a corresponding scanning line among the plurality of scanning lines, a first terminal connected to a corresponding data line among the plurality of data lines, and a second terminal circuit. A switching element having a terminal; a light emitting element connected to the second terminal; and a capacitive element having one terminal connected to the second terminal, wherein the other terminal of the capacitive element corresponds to the corresponding terminal A signal connected to the same scanning line as the control terminal of the switching element and sequentially applied to the plurality of scanning lines includes a three-level voltage, and the gist is that the light emitting element is AC driven by the signal.

  According to this, a simple circuit can be configured, the element can be AC driven without using a special AC power source, the life of the element can be extended, and the manufacturing cost can be reduced. A device can be realized. In addition, the light emitting element of each unit circuit can be AC driven for each unit circuit of one row corresponding to each of the plurality of scanning lines. Furthermore, the light emission period after the switching element is turned off can be appropriately adjusted.

  The electro-optical device driving method according to the present invention includes a plurality of scanning lines, a plurality of data lines, and a plurality of unit circuits arranged corresponding to intersections of the scanning lines and the data lines. Each of the unit circuits includes a control terminal connected to a corresponding scanning line among the plurality of scanning lines, a first terminal connected to a corresponding data line among the plurality of data lines, and a second terminal circuit. A switching element having a terminal; a light emitting element connected to the second terminal; and a capacitive element having one terminal connected to the second terminal, wherein the other terminal of the capacitive element corresponds to the corresponding terminal A signal connected to the preceding scanning line selected before the scanning line to which the control terminal of the switching element is connected, and sequentially applied to the plurality of scanning lines includes a three-level voltage. AC light-emitting element And summary to be dynamic.

  According to this, a simple circuit can be configured, the element can be AC driven without using a special AC power source, the life of the element can be extended, and the manufacturing cost can be reduced. A device can be realized. In addition, the light emitting element of each unit circuit can be AC driven for each unit circuit of one row corresponding to each of the plurality of scanning lines. Furthermore, the light emission period after the switching element is turned off can be appropriately adjusted.

  The electro-optical device driving method according to the present invention includes a plurality of scanning lines, a plurality of data lines, and a plurality of unit circuits arranged corresponding to intersections of the scanning lines and the data lines. Each of the unit circuits includes a control terminal connected to a corresponding scanning line among the plurality of scanning lines, a first terminal connected to a corresponding data line among the plurality of data lines, and a second terminal circuit. A switching element having a terminal, a light emitting element connected to the second terminal, and a capacitor element having one terminal connected to the second terminal, the other terminal of the capacitor element being a capacitor line The signals connected and sequentially applied to the plurality of scanning lines and the capacitor lines include two-level voltages, respectively, and the light-emitting elements are AC-driven by the signals.

  According to this, a simple circuit can be configured, the element can be AC driven without using a special AC power source, the life of the element can be extended, and the manufacturing cost can be reduced. A device can be realized. In addition, by changing the timing of applying the reverse polarity voltage to the other terminal of the capacitor element to bias the light emitting element in the reverse direction, the light emission period after the switching element is turned off is appropriately adjusted. be able to.

In this electro-optical device, the capacitor line is provided independently for each unit circuit of one row corresponding to each of the plurality of scanning lines.
According to this, the light emitting element of each unit circuit can be AC driven for each row of unit circuits corresponding to each of the plurality of scanning lines.

  In this electro-optical device driving method, each of the plurality of scanning lines is selected once per frame, and each light emitting element of the plurality of unit circuits is supplied to the plurality of data lines as an analog voltage signal. In response to this, light is emitted once per frame.

According to this, each light emitting element of a plurality of unit circuits can be made to emit light with brightness according to the analog voltage signal once per frame.
In this electro-optical device driving method, one frame is divided into a plurality of subfields, and gradation control is performed by subfield driving.

  According to this, by combining the method of driving the light emitting element with alternating current and gradation control by subfield driving, light is emitted a plurality of times within one frame, so that a bright screen can be easily obtained as compared with a normal driving method. .

  Here, “gradation control by subfield driving” means that one frame is divided into a plurality of subfields, and each of the binary voltages based on the gradation data is divided into a plurality of subfields. A method for performing digital gradation control by time division by writing in a light emitting element.

An electronic apparatus according to an aspect of the invention includes the electro-optical device according to any one of claims 5 to 8.
According to this, the display quality of the electronic device can be improved. Therefore, an electronic device with good visibility can be realized.

1 is a block diagram showing an EL display device according to a first embodiment. The block diagram which shows the equivalent circuit and drive circuit of the display panel part shown in FIG. FIG. 3 is a circuit diagram showing an equivalent circuit of one pixel of the display panel unit shown in FIG. 2. (A)-(c) is a wave form diagram which shows the signal of the scanning line in the display panel part shown in FIG. (A), (b) is a wave form diagram which shows the data signal in the display panel part shown in FIG. The block diagram which shows the equivalent circuit and drive circuit of the display panel part in 2nd Embodiment. (A)-(c) is a wave form diagram which shows the signal of the scanning line in the display panel part shown in FIG. The block diagram which shows the equivalent circuit and drive circuit of the display panel part in 3rd Embodiment. (A)-(c) is a wave form diagram which shows the signal of the scanning line and capacitance line in the display panel part shown in FIG. (A)-(c) is a wave form diagram which shows the signal of the scanning line in 4th Embodiment. The wave form diagram which shows an example of the drive method by 4th Embodiment. (A)-(c) is a wave form diagram which shows the signal of the scanning line in 5th Embodiment. (A)-(c) is a wave form diagram which shows the signal of the scanning line in 6th Embodiment. The perspective view which shows the personal computer using EL display apparatus. The wave form diagram which shows the signal of the scanning line in the modification of 1st Embodiment.

Hereinafter, embodiments embodying the present invention will be described with reference to the drawings.
[First Embodiment]
A first embodiment in which the present invention is applied to an EL display device as an electro-optical device will be described with reference to FIGS.

FIG. 1 shows a circuit configuration of an EL display device, FIG. 2 shows an equivalent circuit and a drive circuit of a display panel unit, and FIG. 3 shows an equivalent circuit of one pixel.
In FIG. 1, the EL display device 20 includes a display panel unit 21, a scanning line driving circuit 22, a data line driving circuit 23, and a control circuit 24. The scanning line driving circuit 22 and the data line driving circuit 23 are controlled by the control circuit 24 to drive the plurality of scanning lines Y1 to Ym and the plurality of data lines X1 to Xn. The control circuit 24 receives a data signal, a synchronization signal, and a clock signal from an external circuit. In addition, a vertical synchronization signal, a clock signal, and the like are supplied from the control circuit 24 to the scanning line driving circuit 22 through a signal line. A data signal, a horizontal synchronizing signal, and the like are supplied from the control circuit 24 to the data line driving circuit 23 through the signal line.

  Each element 21 to 24 of the EL display device 20 may be composed of independent electronic components. For example, each element 21 to 24 may be constituted by a one-chip semiconductor integrated circuit device. Moreover, you may be comprised as an electronic component in which all or one part of each element 21-24 was united. For example, the scanning line driving circuit 22 and the data line driving circuit 23 may be integrally formed on the display panel unit 21. All or a part of each element 21 to 24 may be configured by a programmable IC chip, and the function may be realized by software by a program written in the IC chip.

  As shown in FIG. 2, the display panel unit 21 includes n columns of data lines X1 to Xn (n is an integer) extending along the column direction and m rows of scanning lines Y1 to Ym (m) extending along the row direction. Is provided with a plurality of (m × n) pixels 30 arranged in a matrix at the intersection with (integer).

  The unit circuit 30A (equivalent circuit of one pixel shown in FIG. 3) of each pixel 30 includes, as shown in FIGS. 2 and 3, one switching transistor Qs as a switching element and an organic element as an electronic element or a light emitting element. An EL element 31 and a holding capacitor Cp as a capacitive element are provided. The unit circuit 30A of each pixel 30 corresponds to the electronic circuit of the present invention.

  The switching transistor (hereinafter referred to as “transistor”) Qs is a thin film transistor (TFT). In this example, the transistor Qs is composed of an n-channel FET. The transistor Qs has a gate that is a control terminal, a source that is a first terminal, and a drain that is a second terminal. The gate of the transistor Qs is connected to one of the scanning lines Y1 to Ym, the source is connected to one of the data lines X1 to Xn, and the organic EL element 31 and the holding capacitor Cp are connected in parallel to the drain. It is connected.

  The organic EL element 31 is a current-driven light emitting element in which a light emitting layer is composed of an organic EL and emits light when supplied with current. The terminal a (one terminal) of the holding capacitor Cp of each pixel 30 is connected to the drain of one corresponding transistor Qs, and the other terminal b (the other terminal) of the holding capacitor Cp is one corresponding one. It is connected to the same scanning line as the gate of the transistor Qs. For example, the terminal b of each holding capacitor Cp of the plurality of pixels 30 corresponding to the scanning line Y1 is connected to the same scanning line Y1 as the gate of the corresponding transistor Qs. The anode (one terminal) of the organic EL element 31 of each pixel 30 is connected to the drain of the transistor Qs, and the cathode (the other terminal) is connected to the common electrode (cathode electrode). In this example, the potential of the cathode electrode is a general potential of 0 (V), but any voltage value lower than Vd (V) that is the voltage value of the data signal can be used.

  In the EL display device 20 of the first embodiment, each of the plurality of scanning lines Y1 to Ym is selected once per frame, and each organic EL element 31 of the plurality of pixels 30 is replaced with the plurality of data lines X1 to X1. Light is emitted once per frame in accordance with an analog voltage signal (data signal) supplied to each of Xn.

  Further, in the EL display device 20, as shown in FIGS. 4A to 4C, signals applied to each of the plurality of scanning lines Y1 to Ym are a reference voltage GND and a voltage Vg1 (scanning signal). The voltage Vg1 includes a three-level voltage with a voltage −Vg2 having a polarity opposite to that of the voltage Vg1. The organic EL element 31 of each pixel 30 is AC driven by these three levels of voltage.

  That is, the voltage Vg1 is applied to each of the plurality of scanning lines Y1 to Ym in each selection period h1 (one horizontal scanning period) in which one of the scanning lines Y1 to Ym is sequentially selected, and the next scanning line is selected. The voltage −Vg2 is applied during the reverse bias period h2 that coincides with the period h1, and the reference voltage GND is applied during other periods. For example, as shown in FIG. 4A, the voltage Vg1 is applied to the scanning line Y1 in the selection period h1, and it coincides with the selection period h1 of the next-stage scanning line Y2 selected next to the scanning line Y1. The voltage −Vg2 is applied during the reverse bias period h2. Similarly, as shown in FIG. 4B, the voltage Vg1 is applied to the scanning line Y2 during the selection period h1, and the voltage −Vg2 is applied during the reverse bias period h2. Then, as shown in FIG. 4C, the voltage Vg1 is applied to the scanning line Ym during the selection period h1, and the voltage −Vg2 is applied during the reverse bias period h2.

  Next, the operation of the EL display device 20 of this example will be described with reference to FIGS. 5A and 5B show voltage waveforms of data signals applied to each of the plurality of data lines X1 to Xn.

  In each selection period h1 in which the plurality of scanning lines Y1 to Ym are sequentially selected, the voltage Vg1 is applied to the gate of each transistor Qs of the plurality of pixels 30 corresponding to one scanning line to be selected, so that each transistor Qs is turned on. become. As a result, the voltage Vd (see FIGS. 5A and 5B) of the data signal (analog voltage signal) supplied simultaneously from the plurality of data lines X1 to Xn corresponds to each organic signal via each transistor Qs. The voltage is applied to the EL element 31 and each holding capacitor Cp.

  Thereby, in each selection period h1, a charge Q corresponding to the voltage Vd of the data signal is accumulated in each holding capacitor Cp, and a current corresponding to the data signal flows to the organic EL element 31 through each transistor Qs. The organic EL element 31 emits light with brightness according to the current. At this time, each organic EL element 31 is biased in the forward direction. That is, in FIG. 2, point A is kept at a higher potential than point B.

When the selection period h1 ends, the voltage −Vg2 is applied to the scanning line that has been selected for the reverse bias period h2 from the end of the selection period h1. For example, the voltage −Vg2 is applied to the scanning line Y1 from the end of the selection period h1 of the scanning line Y1 to the reverse bias period h2. As a result, in each of the unit circuits 30A of the plurality of pixels 30 corresponding to the scanning line for which the selection period h1 has ended, for example, the scanning line Y1, each holding is performed during the reverse bias period h2 to which the voltage −Vg2 is applied. A voltage obtained by dividing the voltage −Vg2 by the capacitance Cs of the capacitor Cp and the capacitance C0 of the organic EL element 31 is applied to the point A. The potential Va at point A at this time is expressed by the following equation. (Generally Cgs is ignored because Cgs << C0, Cs)
Va = −C0 / (C0 + Cs) × Vg2
As a result, each organic EL element 31 of the plurality of pixels 30 corresponding to the scanning line for which the selection period h1 has ended is biased in the reverse direction. In addition, since the voltage applied to the scanning line after the selection period h1 is changed from Vg1 to -Vg2 simultaneously with the end of the selection period h1, light emission of each organic EL element 31 is stopped. Such an operation is repeated for each scanning line to be selected while sequentially selecting the plurality of scanning lines Y1 to Ym to form a screen of one frame, and each organic EL element 31 of the plurality of pixels 30 corresponding to each scanning line. Is AC driven.

  In the EL display device 20 of the present embodiment, as one specific example, a capacitor Cs that is 1/3 of the capacitor C0 of the organic EL element 31 is formed on the TFT substrate. Further, in order to obtain sufficient brightness by emitting light once at 60 Hz for each organic EL element 31, it is necessary to apply a voltage of Va = 7V to the point A during the selection period h1. When calculated backward from this, Vg2 becomes 9.3V. To turn on the transistor Qs, Vg1 of 15 V was required. Therefore, it is necessary to apply a signal having a total amplitude of 24.3 V to each scanning line.

According to 1st Embodiment comprised as mentioned above, there exist the following effects.
A signal applied to each of the plurality of scanning lines Y1 to Ym includes three levels of a reference voltage GND, a voltage Vg1, and a voltage −Vg2 having a polarity opposite to that of the voltage Vg1. The organic EL element 31 of each pixel 30 can be AC driven by the voltage.

  One voltage Vg1 among the three levels of voltages is sequentially applied to the plurality of scanning lines Y1 to Ym as shown in FIGS. 4A to 4C, so that the plurality of scanning lines are sequentially selected. Thus, when each transistor Qs of the plurality of pixels 30 corresponding to the scanning line to be selected is turned on in each selection period h1 in which the plurality of scanning lines are sequentially selected, according to the data signal supplied from the data lines X1 to Xn. Current flows through each organic EL element 31, and each organic EL element 31 emits light. At this time, the organic EL element 31 is biased in the forward direction. By applying a voltage −Vg2 having a polarity opposite to that of the voltage Vg1 to each scanning line in which the selection period h1 has ended, the organic EL elements 31 of the plurality of pixels 30 corresponding to the scanning line are biased in the reverse direction. The In this way, the organic EL elements 31 of the unit circuits 30A of the plurality of pixels 30 are AC driven, so that the lifetime of the organic EL elements 31 can be extended.

  In each unit circuit 30A of the plurality of pixels 30, only one transistor Qs for switching elements is required, and a special AC power source or power supply line for AC driving the organic EL element 31 is not necessary. For this reason, unlike the above-described prior art, since many components are not packed in one pixel, the effective light emitting area of each pixel 30 increases and the aperture ratio increases. As a result, the current flowing through the organic EL element 31 can be reduced to reduce the emission intensity of the organic EL element 31 per unit area, and the amount of heat generated by the organic EL element 31 can be reduced to keep the element temperature low. become. This also makes it possible to extend the life of the light emitting element.

  In each unit circuit 30A of the plurality of pixels 30, only one transistor Qs for the switching element is required, and a special AC power source and power supply line for AC driving the organic EL element 31 are not required, so that the number of transistors is small. A unit circuit 30A having a simple configuration with the number of parts is obtained. In addition, since the configuration of each unit circuit 30A is simplified, it is less susceptible to dust during the manufacturing process, and the yield is improved. This reduces manufacturing costs.

  Therefore, with the above effects, the circuit can be configured with a simple circuit, the organic EL element 31 can be AC driven without using a special AC power source, and the life of the organic EL element 31 can be extended and the manufacturing cost can be reduced. Therefore, the low-cost EL display device 20 can be realized.

  The organic EL element 31 of each unit circuit 30A can be AC driven for each row of unit circuits 30A corresponding to each of the plurality of scanning lines Y1 to Ym. This eliminates the need for a special AC power source having a large current supply capability in order to AC drive the entire display screen at a time as in the above-described prior art, thereby realizing the EL display device 20 with low power consumption.

  In this embodiment, the reverse bias period h2 is the same as the selection period h1 (one horizontal scanning period), but the reverse bias effective value and drive voltage are arbitrarily adjusted by appropriately setting the reverse bias period. can do. Here, the “drive voltage” refers to a voltage for turning on the transistor Qs of each pixel 30 and corresponds to the voltage Vg1. For example, the reverse bias period may be an integral multiple of the selection period h1. As shown in FIG. 15, by setting the reverse bias period h2 to twice the selection period h1 (2h1), the voltage for reverse biasing each organic EL element 31 can be reduced to ½ of −Vg2. it can. As a result, AC driving may be performed.

[Second Embodiment]
FIG. 6 shows a second embodiment in which the present invention is applied to an EL display device 20 as an electro-optical device. In the description of this embodiment, the same members and signals as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  In the second embodiment, the terminals b of the holding capacitors Cp of the plurality of pixels 30 arranged in a matrix at intersections of the scanning lines Y1 to Ym and the data lines X1 to Xn are different from those in the first embodiment. It is different from the first embodiment in that it is connected. Other configurations are the same as those of the first embodiment.

  The terminal b of each holding capacitor Cp is connected via the gate line 40 to the preceding scanning line selected one before the scanning lines Y1 to Ym. For example, the terminal b of each holding capacitor Cp of each of the plurality of pixels 30 at each intersection of the scanning line Ym and the data lines X1 to Xn is connected to the scanning line Ym−1 that is the preceding scanning line via the gate line 40. It is connected to the. Since there is no preceding scanning line for the scanning line Y1 in the first row, a dummy scanning line Y0 is provided as the preceding scanning line, and each holding capacitor Cp of the plurality of pixels 30 corresponding to the scanning line Y1 is provided. The terminal b is connected to the dummy scanning line Y0 through the gate line 40.

  Also in the EL display device 20 of the second embodiment, the signals applied to each of the plurality of scanning lines Y1 to Ym are the reference voltage GND and the voltage as shown in FIGS. It includes three levels of voltage: Vg1 (scanning signal) and voltage -Vg2 having a polarity opposite to that of the voltage Vg1. The organic EL element 31 of each pixel 30 is AC driven by these three levels of voltage.

  Therefore, the voltage Vg1 is applied to each of the plurality of scanning lines Y1 to Ym in each selection period h1 for sequentially selecting one of the scanning lines Y1 to Ym, and during the selection period h1 of the next scanning line. A reference voltage GND is applied. The voltage −Vg2 is applied during the reverse bias period h2 from the end of the selection period h1 of the next scanning line, and then returns to the reference voltage GND. For example, as shown in FIG. 7A, the voltage Vg1 is applied to the scanning line Y1 during the selection period h1, and the reference voltage GND is applied during the selection period h1 of the next scanning line. Then, the voltage −Vg2 is applied between the end of the selection period h1 of the next-stage scanning line and the reverse bias period h2, and then returns to the reference voltage. As for the scanning lines Y2 to Ym, as shown in FIGS. 7B and 7C, three-level voltages are sequentially applied at the same timing as the scanning line Y1. For example, the reference voltage GND is applied to the dummy scanning line Y0 during the selection period h1 of the scanning line Y1, and the voltage −Vg2 is applied between the end of the selection period h1 of the scanning line Y1 and the reverse bias period h2. Thereafter, the reference voltage GND is applied.

Next, the operation of the EL display device 20 of this example will be described with reference to FIG.
During each selection period h1 in which the plurality of scanning lines Y1 to Ym are sequentially selected, the voltage Vg1 is applied to the gate of each transistor Qs of the plurality of pixels 30 corresponding to the selected scanning line, and each transistor Qs is turned on. It becomes a state. As a result, during each selection period h1, a charge Q corresponding to the voltage Vd of the data signal is accumulated in each holding capacitor Cp, and a current corresponding to the data signal flows to the organic EL element 31 through each transistor Qs. The organic EL element 31 emits light with brightness according to the current. At this time, each organic EL element 31 is biased in the forward direction. That is, in FIG. 6, point A is kept at a higher potential than point B.

  During the period from the end of each selection period h1 to the reverse bias period h2, the voltage −Vg2 is applied to the preceding scanning line to which the terminals b of the holding capacitors of the plurality of pixels 30 corresponding to the scanning line that has been selected are connected. Applied. For example, during the reverse bias period h2 from the end of the selection period h1 of the scanning line Y2, a voltage is applied to the preceding scanning line Y1 to which the terminals b of the holding capacitors of the plurality of pixels corresponding to the scanning line Y2 are connected. -Vg2 is applied. Thereby, in each of the unit circuits 30A of the plurality of pixels 30 corresponding to the scanning line, for example, the scanning line Y1, for which the selection period h1 has been completed, the potential at the point A during the reverse bias period h2 to which the voltage −Vg2 is applied. Va is applied.

  Thereby, in each organic EL element 31 of the plurality of pixels 30 corresponding to the scanning line for which the selection period h1 has ended, the voltage applied to the scanning line changes from Vg1 to −Vg2 simultaneously with the end of the selection period h1. , Biased in the reverse direction, stops light emission.

  Such an operation is repeated for each scanning line to be selected while a plurality of scanning lines Y1 to Ym are sequentially selected to form a screen of one frame, and each organic EL element 31 of each of the plurality of pixels 30 is AC driven. The

According to the second embodiment configured as described above, the same operational effects as those of the first embodiment described above can be obtained.
[Third Embodiment]
FIG. 8 shows a third embodiment in which the present invention is applied to an EL display device 20 as an electro-optical device. In the description of this embodiment, the same members and signals as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  In the third embodiment, the terminals b of the holding capacitors Cp of the plurality of pixels 30 arranged in a matrix at the intersections of the scanning lines Y1 to Ym and the data lines X1 to Xn are different from those in the first embodiment. It is different from the first embodiment in that it is connected. Other configurations are the same as those of the first embodiment.

Terminals b of the holding capacitors of the plurality of pixels 30 corresponding to the scanning lines Y1 to Ym are connected to capacitance lines 41 _{1 to} 41 _m corresponding to the plurality of scanning lines Y1 to Ym, respectively.

The capacitance lines 41 _{1 to} 41 _m are provided independently for each unit circuit 30A for one row corresponding to each of the plurality of scanning lines Y1 to Ym. For example, as shown in FIG. 8, the terminals b of the holding capacitors of the plurality of pixels 30 corresponding to the first row scanning line Y1 are connected to the first row capacitance line 41 ₁ corresponding to the scanning line Y1. It is connected. Similarly, the terminals b of the holding capacitors of the plurality of pixels 30 respectively corresponding to the second scanning line Y2 to the mth scanning line Ym are connected to the second row corresponding to the scanning lines Y2 to Ym. To the m-th capacity lines 41 _{2 to} 41 _m .

Further, in the EL display device 20 of the third embodiment, as shown in FIGS. 9A to 9C, signals applied to each of the plurality of scanning lines Y1 to Ym are the reference voltage GND and the voltage. A voltage of two levels with Vg1 (scanning signal) is included. Further, as shown in FIGS. 9A to 9C, the signals applied to the plurality of capacitance lines 41 _{1 to} 41 _m are the reference voltage GND and the voltage −Vg2 having a polarity opposite to that of the voltage Vg1. Includes two levels of voltage. The organic EL element 31 of each pixel 30 is AC driven by two-level voltages applied to the plurality of scanning lines Y1 to Ym and the plurality of capacitance lines 41 _{1 to} 41 _m , respectively.

That is, the voltage Vg1 is applied to each of the plurality of scanning lines Y1 to Ym in each selection period h1 in which one of the scanning lines Y1 to Ym is sequentially selected, and the reference voltage GND is applied to the other periods. Further, the voltage −Vg2 is applied to each of the plurality of capacitance lines 41 _{1 to} 41 _m from the end of the corresponding scanning line selection period h1 to the reverse bias period h2, and the reference voltage GND is applied to the other periods. It is to be applied.

Next, the operation of the EL display device 20 of this example will be described with reference to FIG.
During each selection period h1 in which the plurality of scanning lines Y1 to Ym are sequentially selected, the voltage Vg1 is applied to the gate of each transistor Qs of the plurality of pixels 30 corresponding to the selected scanning line, and each transistor Qs is turned on. It becomes a state. As a result, during each selection period h1, a charge Q corresponding to the voltage Vd of the data signal is accumulated in each holding capacitor Cp, and a current corresponding to the data signal flows to the organic EL element 31 through each transistor Qs. The organic EL element 31 emits light with brightness according to the current. At this time, each organic EL element 31 is biased in the forward direction. That is, in FIG. 8, point A is kept at a higher potential than point B.

One of the capacitance lines 41 _{1 to} 41 _m to which the terminals b of the holding capacitors of the plurality of pixels 30 corresponding to the scanning line that has been selected are connected from the end of each selection period h1 to the reverse bias period h2. One voltage -Vg2 is applied. For example, the voltage −Vg2 is applied to the capacitor line 41 ₁ from the end of the selection period h1 of the scanning line Y1 to the reverse bias period h2 (see FIG. 9A). As a result, the potential Va at the point A is applied to each unit circuit 30A of the plurality of pixels 30 corresponding to the scanning line Y1, for example, the scanning line Y1, after the selection period h1 is applied, while the voltage −Vg2 is applied. .

Thereby, in each organic EL element 31 of the plurality of pixels 30 corresponding to the scanning line for which the selection period h1 has ended, a voltage applied to one of the capacitance lines 41 _{1 to} 41 _m corresponding to the scanning line is selected. Since it changes from Vg1 to -Vg2 simultaneously with the end of h1, it is biased in the reverse direction and stops light emission.

  Such an operation is repeated for each scanning line to be selected while the plurality of scanning lines Y1 to Ym are sequentially selected to form a screen of one frame, and the organic EL elements 31 of the plurality of pixels 30 are AC driven.

According to the third embodiment configured as described above, the same operational effects as those of the first embodiment can be obtained.
[Fourth Embodiment]
Next, an EL display device 20 according to the fourth embodiment will be described with reference to FIG. FIG. 10 shows waveforms of signals applied to the scanning lines Y1 to Ym.

  In the EL display device 20 of the fourth embodiment, gradation control (digital level) by subfield driving (time-division driving) is applied to the method of alternating-current driving the organic EL elements 31 of the pixels 30 described in the first embodiment. Control).

<Gradation control by subfield driving>
The control circuit 24 of the EL display device 20 controls the scanning line driving circuit 22 and the data line driving circuit 23 so that ^2N gradation display is performed by subfield driving. In the “subfield driving”, one frame is divided into N subfields having a length corresponding to each bit of N-bit gradation data. Here, “one frame” refers to a period in which display of one screen is configured by sequentially selecting one of the scanning lines Y1 to Ym and writing data signals to all the pixels 30. The period of N sub-feeds is set to a length corresponding to each bit, that is, a ratio of 1 (2 ⁰ ): 2 (2 ¹ ): 4 (2 ² )... 2 ^N −1. Based on the grayscale data shown in Table 1 below, one of the binary voltages is written to each pixel 30 with the period T of the shortest subfield among the N subfields set in this way, and the ^2N grayscales Display.

Specifically, the control circuit 24 of this example performs gradation display of 2 ³ gradations (2 ^N , N = 3, 8 gradations), that is, gradation display of gradation degree 0 to gradation degree 7. As shown in FIG. 10, one frame is divided into three subfields SF1, SF2, and SF3. Each period (time length) of the three subfields SF1, SF2, and SF3 is set to a length corresponding to each bit of the 3-bit gradation data (according to the binary system), that is, 1 (2 ⁰ ): 2 The ratio is set to (2 ¹ ): 4 (2 ² ). Accordingly, each period of the subfields SF2 and SF3 is twice or four times that of the subfield SF1. In this case, of the three subfields SF1, SF2, and SF3, the subfield having the shortest period is SF1, and a binary voltage as a data signal is supplied to each pixel 30 in the period T (see FIG. 10) of the subfield SF1. Write one of these. The “binary voltage” mentioned here is an L level voltage 0 (V) and an H level voltage V1 (V).

As described above, in the gradation control by the subfield driving of this example, the data signal is written to each pixel 30 at a frame frequency of 60 Hz (frame period is 1/60 sec), and each pixel 30 is set in one frame. One of binary voltages is written every period T. That is, as shown in FIG. 10, the data signal is written to each pixel 30 seven times (2 ³ -1 times) every period T in one frame of 1/60 second (sec). For this purpose, the control circuit 24 outputs a vertical scanning start signal DY (not shown) to the scanning line driving circuit 22 seven times at intervals of a period T in one frame based on the synchronization signal and the clock signal. .

Each time a vertical scanning start signal DY (hereinafter simply referred to as a start signal DY) is input from the control circuit 24, the scanning line driving circuit 22 generates and outputs the scanning signals G1 to Gm in order, thereby outputting the scanning line. One of Y1 to Ym is sequentially selected. That is, when the first start signal DY is input at the beginning of one frame, the scanning line driving circuit 22 receives the first scanning signal G1 _{1 as} shown in FIGS. 10 (a), (b) and (c). To Gm ₁ are sequentially output, and the scanning lines Y1 to Ym are sequentially selected. This selection period is the first selection period t1 in one frame. The scanning line driving circuit 22, when 2 to seventh start signal DY each time period T has elapsed from the time of input of the first start signal DY are input, the second scan signals G1 ₂ ~ Gm ₂ ... Seventh scanning signals G 1 _{7 to} Gm ₇ are sequentially output, and the scanning lines Y 1 to Ym are selected in order. These selection periods are the second to seventh selection periods t1 in one frame. In this manner, the operation of sequentially selecting the scanning lines Y1 to Ym is repeated seven times in one frame.

  In addition to the synchronization signal and the clock signal, 3-bit gradation data is input to the control circuit 24 as a binary data signal that is an image signal in order to perform field driving. The gradation data is eight kinds of binary data signals from (000) to (111) as shown in Table 1 below.

階調データ（０００）は一つの画素３０に階調度０の表示（黒表示：有機ＥＬ素子３１の発光強度が０の表示）をするためのデータであり、階調データ（１１１）は一つの画素３０に階調度７の表示（白表示：有機ＥＬ素子３１の発光強度が７の表示）をするためのデータである。また、階調データ（００１）〜（１１０）はそれぞれ、一つの画素３０に中間の階調度１〜６の表示（有機ＥＬ素子３１の発光強度１〜６の表示）をするためのデータである。

The gradation data (000) is data for displaying a gradation of 0 on one pixel 30 (black display: display of the light emission intensity of the organic EL element 31 of 0), and the gradation data (111) is one. This is data for displaying a gradation of 7 on the pixel 30 (white display: display of the light emission intensity of the organic EL element 31 of 7). The gradation data (001) to (110) are data for displaying an intermediate gradation degree 1 to 6 on one pixel 30 (displaying the light emission intensity 1 to 6 of the organic EL element 31). .

  As shown in Table 1, the data line driving circuit 23 outputs a data signal to each pixel 30 corresponding to one selected scanning line during each selection period t1 in which one of the scanning lines Y1 to Ym is sequentially selected. Either (voltage 0) or H (voltage V1) is output all at once.

  Also, the above table 1 shows the gradation data corresponding to the above-described eight kinds of gradations, the subfield SF1 (first selection period t1) and SF2 (second and third selection periods t1) in one frame. ) And SF3 (fourth to seventh selection periods t1), and the relationship with the data signal written to one pixel 30 is shown.

  For example, when the gradation data (000) in Table 1 is used to display each pixel 30 with a gradation of 0, subfield SF1 (first selection period t1) and SF2 (second and third selection periods t1) And the L data signal is written in each pixel 30 in seven selection periods t1 of SF3 (fourth to seventh selection periods t1). In addition, when displaying gradation level 1 on each pixel 30 with gradation data (001), as shown in Table 1, an H data signal is written only in the first selection period t1, and the second to seventh times. The L data signal is written during each of the selection periods t1. Similarly, in the case of displaying gradation levels 2 to 7 on each pixel 30 with the gradation data (010) to (111) in Table 1, L or H data signals in each selection period t1 seven times in one frame. Is to be written.

  In this manner, when the L or H data signal is written in each selection period t1 of seven times in one frame, the organic EL element 31 of each pixel 30 has the gradation data (000) to (111) in Table 1. The pixel 30 emits light with a light emission intensity according to the above, and each pixel 30 performs gradation display of eight gradations.

  In this EL display device 20, the signals (scanning signals) applied to each of the plurality of scanning lines Y1 to Ym are the reference voltage GND and the voltage Vg1 as shown in FIGS. (Scanning signal) and the voltage Vg1 include three levels of voltage -Vg2 having a polarity opposite to that of the voltage Vg1. The organic EL element 31 of each pixel 30 is AC driven by these three levels of voltage.

  That is, as shown in FIGS. 10A to 10C, the signal (scanning signal) applied to each of the scanning lines Y1 to Ym becomes the voltage Vg1 (scanning signal) in the selection period t1, and the selection period t1. The voltage becomes −Vg2 in the reverse bias period (t1 + τ) from the end of, and becomes the reference voltage GND in the remaining period until the next selection period.

  FIG. 11 shows an example of driving according to the fourth embodiment. In one frame, each pixel 30 corresponding to the scanning lines Y1 to Yk is displayed with a gradation of 0 (black display), and the scanning lines Yk + 1 to 1 are displayed. A waveform of a data signal written to each pixel 30 when displaying each pixel 30 corresponding to Ym with a gradation level of 7 (white display) is shown. In this case, when writing a data signal to each pixel 30 in one frame seven times for each period T, 0 (V) data is stored in each pixel 30 corresponding to the scanning lines Y1 to Yk in each period T. A signal is written, and a data signal of V1 (V) is written to each pixel 30 corresponding to the scanning lines Yk + 1 to Ym.

According to 4th Embodiment comprised as mentioned above, while there exist an effect similar to the said 1st Embodiment, there exist the following effects.
-Combining gradation control by subfield driving with the method of alternating current driving the organic EL element 31 of each pixel 30 described in the first embodiment allows the organic EL element 31 of each pixel 30 to be multiple times within one frame ( Since light is emitted seven times in this example, a bright screen can be easily obtained as compared with a normal driving method.

In order to cause the organic EL element 31 of each pixel 30 to emit light, gradation control by the subfield driving is performed. That is, the L or H data signal is written in each of the seven selection periods t1 in one frame, so that the organic EL element 31 of each pixel 30 corresponds to the gradation data (000) to (111) in Table 1. in the light-emission intensity, and performing gradation display 2 ³ gradations in each pixel 30. As a result, the data signal writing cycle is shortened, so that the charge Q accumulated in each holding capacitor Cp during each selection period t1 can be reduced. Therefore, even with high definition, a bright display with low power consumption can be realized.

In the present embodiment, the effective value of the reverse bias and the drive voltage can be arbitrarily adjusted by appropriately setting the reverse bias period (t1 + τ).
[Fifth Embodiment]
Next, an EL display device 20 according to a fifth embodiment will be described with reference to FIG. FIG. 12 shows the waveforms of signals applied to the scanning lines Y1 to Ym.

  In the EL display device 20 of the fifth embodiment, the above-described gradation control by subfield driving is combined with the method of alternating-drive the organic EL element 31 of each pixel 30 described in the second embodiment.

  In this EL display device 20, as shown in FIGS. 12A to 12C, signals (scanning signals) applied to each of the plurality of scanning lines Y1 to Ym are a reference voltage GND and a voltage Vg1 (scanning). Signal) and a voltage −Vg2 having a polarity opposite to that of the voltage Vg1 are included. The organic EL element 31 of each pixel 30 is AC driven by these three levels of voltage.

  As shown in FIGS. 12A to 12C, the signal applied to each of the scanning lines Y1 to Ym becomes the voltage Vg1 (scanning signal) in the selection period t1, and the period τ1 from the end of the selection period t1. Becomes the reference voltage GND. Thereafter, the voltage becomes −Vg2 in the reverse bias period τ2, and becomes the reference voltage GND in the remaining period until the next selection period. Here, the period τ1 and the reverse bias period τ2 are the same as the selection period t1, respectively.

According to 5th Embodiment comprised as mentioned above, while there exist an effect similar to the said 4th Embodiment, there exist the following effects.
In the present embodiment, the effective value of the reverse bias and the drive voltage can be arbitrarily adjusted by appropriately setting the reverse bias period τ2.

[Sixth Embodiment]
Next, an EL display device 20 according to a sixth embodiment will be described with reference to FIG. FIG. 13 shows waveforms of signals applied to the scanning lines Y1 to Ym.

  In the EL display device 20 of the sixth embodiment, the above-described gradation control by subfield driving is combined with the method of alternating-current driving the organic EL element 31 of each pixel 30 described in the third embodiment.

In this EL display device 20, as shown in FIGS. 13A to 13C, the signals applied to each of the scanning lines Y1 to Ym are two levels of a reference voltage GND and a voltage Vg1 (scanning signal). Contains the voltage of Further, as shown in FIGS. 13A to 13C, signals applied to the capacitance lines 41 _{1 to} 41 _m are divided into two levels, that is, a reference voltage GND and a voltage −Vg2 having a polarity opposite to that of the voltage Vg1. Contains the voltage of The organic EL element 31 of each pixel 30 is AC driven by two-level voltages applied to the plurality of scanning lines Y1 to Ym and the plurality of capacitance lines 41 _{1 to} 41 _m , respectively.

As shown in FIGS. 10A to 10C, a signal (scanning signal) applied to each of the scanning lines Y1 to Ym becomes the voltage Vg1 (scanning signal) in the selection period t1, and until the next selection period. During the remaining period of time, the reference voltage GND is reached. On the other hand, the signal applied to each of the capacitance lines 41 _{1 to} 41 _m changes from GND to −Vg 2 at the timing at which the voltage of the signal applied to each of the scanning lines Y 1 to Ym changes from GND to Vg 1. It changes from -Vg2 to GND when the reverse bias period τ2 elapses from the end of t1.

According to 5th Embodiment comprised as mentioned above, while there exist an effect similar to the said 4th Embodiment, there exist the following effects.
In the present embodiment, the effective value of the reverse bias and the driving voltage can be arbitrarily adjusted by appropriately setting the reverse bias period τ.

[Electronics]
Next, electronic devices using the display panel unit 21 of the EL display device 20 described in the above embodiments will be described. The display panel unit 21 can be applied to a mobile personal computer as shown in FIG. A personal computer 70 shown in FIG. 14 includes a main body 72 including a keyboard 71 and a display unit 73 using the display panel unit 21. The display panel unit 21 used in the display unit 73 can realize bright display with low power consumption even with high definition.

[Modification]
In addition, this invention can also be changed and embodied as follows.
In each of the above embodiments, an n-channel FET is used as the switching transistor Qs. However, a p-channel FET may be used as the transistor Qs. In that case, by applying a voltage of −Vg1 to the selected scanning line in each selection period h1 in which the plurality of scanning lines Y1 to Ym are sequentially selected, the switching transistor Qs of each pixel 30 corresponding to the scanning line is Turns on. At the end of each selection period h1, by applying a voltage of −Vg2 to the scanning line whose selection period has ended, the organic EL element 31 of each pixel corresponding to the scanning line is biased in the reverse direction.

  In the first embodiment, the voltage −Vg2 is applied to the scanning line that has been selected from the end of each selection period h1 to the reverse bias period h2, but the timing of applying this voltage −Vg2 May be at any time within the non-selection period from the end of each selection period h1 to the next selection. For example, the reverse bias period h2 is provided after a predetermined time from the end of the selection period h1. In this case, during each selection period h1, a data signal is written in each holding capacitor Cp of the plurality of pixels 30 corresponding to the scanning line to be selected, and a charge Q represented by Q = Cs × Vg1 is accumulated. The Therefore, in the non-selection period in which each selection period h1 ends and each transistor Qs is turned off, the charge Q is discharged through the organic EL element 31 until the voltage −Vg2 is applied. Current flows to the organic EL element 31 and emits light. In this way, the organic EL element 31 is caused to emit light using not only each selection period h1 in which the transistor Qs is on but also the charge Q of the holding capacitor Cp accumulated in each selection period h1 as a current source. be able to. Therefore, the light emission period of the organic EL element 31 after the transistor Qs is turned off can be appropriately adjusted by changing the timing of applying the voltage −Vg2 in the non-selection period. Similarly, in the second to sixth embodiments, after the selection period ends, a non-selection period may be provided to discharge at least part of the charge Q and then −Vg2 may be applied.

  In the first embodiment, the reverse bias period does not necessarily have to be the same as the selection period, and it is only necessary to change the value of −Vg2 depending on the length of the reverse bias period and consequently perform AC driving. Although described, this is the same in other embodiments.

In the third embodiment, at the timing when the voltage of the signal applied to each of the scanning lines Y1 to Ym changes from Vg1 to GND, the voltage of the signal applied to each of the capacitance lines 41 _{1 to} 41 _m changes from GND to − Although it changes to Vg2, this invention is not limited to this. At the timing when the voltage of the signal applied to each scanning line changes from GND to Vg1, or at another timing, the voltage of the signal applied to each of the capacitance lines 41 _{1 to} 41 _m changes from GND to −Vg2. May be.

  In each of the above embodiments, the electronic circuit is embodied in the unit circuit 30A to obtain a suitable effect. However, a current other than the organic EL element 23 such as a light emitting element such as an LED, an FED, an electron emitting element, or a plasma element. You may embody in the electronic circuit which drives a drive element. Alternatively, it may be embodied in a storage device such as a RAM.

  In each of the above embodiments, the organic EL element 31 is embodied as the current driving element of each unit circuit 30A, but may be embodied in an inorganic EL element. That is, you may apply this invention to the inorganic EL display which consists of an inorganic EL element.

  In each of the above embodiments, an example is shown in which the present invention is applied to an EL display including a plurality of unit circuits 30A each having an organic EL element 31 of one color. However, each pixel 30 has a red unit circuit and a green unit circuit. The present invention can also be applied to an organic EL display device that performs color display by providing a blue unit circuit.

In the fourth to sixth embodiments, the present invention can be applied to a configuration in which gradation control by subfield driving is performed as follows instead of the gradation control by subfield driving described above. The control circuit 24 divides one frame into 2 ^N −1 subfields having the same length period (period T), and for each subfield, a binary voltage is applied to each pixel based on the gradation data. The scanning line driving circuit 22 and the data line driving circuit 23 are controlled so that either one is written and 2 ^N gradation display is performed. By such gradation control by subfield driving, the same operational effects as in the fourth to sixth embodiments can be obtained.

In the fourth to sixth embodiments, gradation display of 2 ³ gradations (2 ^N , N = 3, 8 gradations), that is, gradation display of gradation degree 0 to gradation degree 7 is performed. However, the present invention is also applied to a configuration in which a value of N is appropriately set and 2 ^N gradation display is performed, that is, gradation display of gradation degree 0 to gradation degree 2 ^N −1 is performed.

  In the fourth to sixth embodiments, the frame frequency is set to 60 Hz. However, the present invention can also be applied to an EL display device in which the frame frequency is twice (120 Hz) or more.

  In each of the above embodiments, the plurality of scanning lines Y1 to Ym are selected one by one in order, but the present invention is not limited to this configuration. For example, the present invention is applied to a configuration in which two or more of the plurality of scanning lines Y1 to Ym are sequentially selected and a configuration in which the plurality of scanning lines Y1 to Ym are sequentially selected by the interlaced scanning method.

  In each of the above embodiments, the scanning line driving circuit 22, the data line driving circuit 23, and the control circuit 24 do not need to be built on the substrate on which the switching transistor Qs is formed, and may be formed as an external circuit. Moreover, you may incorporate at least 1 of them. Here, “built-in” refers to a state of being directly formed on a substrate using a transistor.

  In each of the above embodiments, the electro-optical device has been described as the EL display device 20, but the present invention is not limited to this, and includes an electro-optical device using a light emitting element other than an organic EL element and the electro-optical device. It can also be applied to electronic devices.

  The switching transistor Qs used in the present invention is a TFT using a silicon thin film such as a polysilicon TFT, an amorphous silicon TFT, or a single crystal silicon TFT for the channel layer, or a TFT using a semiconductor thin film such as silicon germanium for the channel layer. It is done.

  The EL display device 20 is not limited to a personal computer as shown in FIG. 14, but can be applied to various electronic devices such as a mobile phone and a digital camera.

0, V1, Vd, Vg1, -Vg2, GND ... voltage, Q ... charge, h1, t1 ... selection period, X1, -Xn ... data line, Y0, Y1-Ym ... scanning line, SF1-SF3 ... subfield, DESCRIPTION OF SYMBOLS 20 ... EL display device as an electro-optical device, 22 ... Scan line drive circuit, 23 ... Data line drive circuit, 24 ... Control circuit, Qs ... Switching transistor as a switching element, Cp ... Holding capacitor as a capacitive element, 30 ... pixel, 30A ... unit circuit, 31 ... organic EL device as an electronic device or light-emitting element, 41 ₁ to 41 _m ... capacitor line.

Claims (15)

In an electronic circuit comprising a switching element,
The switching element includes a control terminal connected to the first wiring, a first terminal connected to the second wiring, and a second terminal connected to the electronic element and the capacitor element,
When a voltage is applied to the control terminal and the switching element is turned on, a data signal supplied from the second wiring is written to the electronic element through the first and second terminals,
An electronic circuit, wherein the electronic element is biased in a reverse direction when a voltage having a polarity opposite to that of the voltage applied to the control terminal is applied to the capacitor element.   2. The electronic circuit according to claim 1, wherein the electronic element is a current-driven light emitting element.   3. The electronic circuit according to claim 2, wherein when the switching element is turned on, a charge corresponding to the voltage of the data signal is accumulated in the capacitor element, and a current corresponding to the data signal is passed through the switching element. When the light emitting element emits light and flows through the light emitting element, and the switching element is turned off, the electric charge accumulated in the capacitor element is discharged through the light emitting element, and a current flows through the light emitting element. An electronic circuit that emits light. In a method for driving an electronic circuit comprising a switching element,
The switching element includes a control terminal connected to the first wiring, a first terminal connected to the second wiring, and a second terminal connected to the electronic element and the capacitor element,
A voltage is applied to the control terminal to set the switching element to an on state, and a data signal supplied from the second wiring is written to the electronic element through the first and second terminals. And the steps
And a second step of biasing the electronic element in a reverse direction by applying a voltage having a polarity opposite to that of the voltage applied to the control terminal to the capacitive element. In an electro-optical device,
A plurality of scanning lines, a plurality of data lines, and a plurality of unit circuits arranged corresponding to the intersection of the scanning lines and the data lines,
Each of the plurality of unit circuits includes a control terminal connected to a corresponding scanning line among the plurality of scanning lines, a first terminal connected to a corresponding data line among the plurality of data lines, and a first terminal A switching element having two terminals, a light emitting element connected to the second terminal, and a capacitive element having one terminal connected to the second terminal, the other terminal of the capacitive element corresponding Connected to the same scanning line as the control terminal of the switching element,
2. The electro-optical device according to claim 1, wherein a signal sequentially applied to the plurality of scanning lines includes a three-level voltage, and the light emitting element is AC driven by the signal. In an electro-optical device,
A plurality of scanning lines, a plurality of data lines, and a plurality of unit circuits arranged corresponding to the intersection of the scanning lines and the data lines,
Each of the plurality of unit circuits includes a control terminal connected to a corresponding scanning line among the plurality of scanning lines, a first terminal connected to a corresponding data line among the plurality of data lines, and a first terminal A switching element having two terminals, a light emitting element connected to the second terminal, and a capacitive element having one terminal connected to the second terminal, the other terminal of the capacitive element corresponding Connected to the preceding scanning line selected before the scanning line to which the control terminal of the switching element is connected,
2. The electro-optical device according to claim 1, wherein a signal sequentially applied to the plurality of scanning lines includes a three-level voltage, and the light emitting element is AC driven by the signal. In an electro-optical device,
A plurality of scanning lines, a plurality of data lines, and a plurality of unit circuits arranged corresponding to the intersection of the scanning lines and the data lines,
Each of the plurality of unit circuits includes a control terminal connected to a corresponding scanning line among the plurality of scanning lines, a first terminal connected to a corresponding data line among the plurality of data lines, and a first terminal A switching element having two terminals, a light emitting element connected to the second terminal, and a capacitor having one terminal connected to the second terminal, the other terminal of the capacitor being a capacitor Connected to the wire
2. The electro-optical device according to claim 1, wherein the signals sequentially applied to the plurality of scanning lines and the capacitor line each include a two-level voltage, and the light emitting element is AC driven by the signals.   8. The electro-optical device according to claim 7, wherein the capacitor line is provided independently for each unit circuit of one row corresponding to each of the plurality of scanning lines. In the driving method of the electro-optical device,
A plurality of scanning lines, a plurality of data lines, and a plurality of unit circuits arranged corresponding to the intersection of the scanning lines and the data lines,
Each of the plurality of unit circuits includes a control terminal connected to a corresponding scanning line among the plurality of scanning lines, a first terminal connected to a corresponding data line among the plurality of data lines, and a first terminal A switching element having two terminals, a light emitting element connected to the second terminal, and a capacitive element having one terminal connected to the second terminal, the other terminal of the capacitive element corresponding Connected to the same scanning line as the control terminal of the switching element,
The signal applied in sequence to the plurality of scanning lines includes a three-level voltage, and the light emitting element is AC driven by the signal. In the driving method of the electro-optical device,
A plurality of scanning lines, a plurality of data lines, and a plurality of unit circuits arranged corresponding to the intersection of the scanning lines and the data lines,
Each of the plurality of unit circuits includes a control terminal connected to a corresponding scanning line among the plurality of scanning lines, a first terminal connected to a corresponding data line among the plurality of data lines, and a first terminal A switching element having two terminals, a light emitting element connected to the second terminal, and a capacitive element having one terminal connected to the second terminal, the other terminal of the capacitive element corresponding Connected to the preceding scanning line selected before the scanning line to which the control terminal of the switching element is connected,
The signal applied in sequence to the plurality of scanning lines includes a three-level voltage, and the light emitting element is AC driven by the signal. In the driving method of the electro-optical device,
A plurality of scanning lines, a plurality of data lines, and a plurality of unit circuits arranged corresponding to the intersection of the scanning lines and the data lines,
Each of the plurality of unit circuits includes a control terminal connected to a corresponding scanning line among the plurality of scanning lines, a first terminal connected to a corresponding data line among the plurality of data lines, and a first terminal A switching element having two terminals, a light emitting element connected to the second terminal, and a capacitor having one terminal connected to the second terminal, the other terminal of the capacitor being a capacitor Connected to the wire
2. The electro-optical device driving method according to claim 1, wherein the signals sequentially applied to the plurality of scanning lines and the capacitor lines each include a two-level voltage, and the light emitting element is AC driven by the signals.   12. The method of driving an electro-optical device according to claim 11, wherein the capacitance line is provided independently for each unit circuit of one row corresponding to each of the plurality of scanning lines. Driving method of optical device.   13. The method of driving an electro-optical device according to claim 9, wherein each of the plurality of scanning lines is selected once per frame, and each light emitting element of the plurality of unit circuits is selected. A method of driving an electro-optical device, wherein light is emitted once per frame in accordance with an analog voltage signal supplied to the plurality of data lines.   13. The electro-optical device driving method according to claim 9, wherein one frame is divided into a plurality of subfields, and gradation control is performed by subfield driving. Driving method.   An electronic apparatus comprising the electro-optical device according to claim 5.

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