JP2008286905A - Display device, driving method thereof, and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device capable of sufficiently securing a holding capacity without changing transistor properties of a driving transistor as a thin-film transistor included in a pixel. <P>SOLUTION: Regarding an active matrix self-luminous display device using light emitting elements such as organic EL elements for pixels, the gate insulating film 54 of the driving transistor as the thin-film transistor included in the pixel and a dielectric film 58 constituting the holding capacity are independently formed. The optimum gate insulating film 54 is used in accordance with the properties required for the driving transistor, and the optimum dielectric film 58 is used so that the sufficient holding capacity can be secured related to a usable area. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a display device, a display device driving method, and an electronic apparatus, and more particularly, a display device using pixels including a current-driven light emitting element such as an organic EL (Electro Luminescence) element and an electronic device using the display device It is suitable for application to equipment.

  In recent years, development of flat self-luminous display devices using organic EL elements for pixels has been actively conducted. An organic EL element is a light emitting element utilizing a phenomenon that light is emitted when an electric field is applied to an organic thin film. Since the organic EL element can be driven by applying a low voltage of 10 V or less, the flat self-luminous display device using the organic EL element is not only low power consumption but also self-luminous. As a result, the liquid crystal display device does not require an illuminating member (backlight, light guide plate, etc.) essential, and can be easily reduced in weight and thickness. Furthermore, since the response time of the organic EL element is as short as about several μs and the response speed is high, no afterimage occurs when displaying a moving image.

  Among flat self-luminous display devices using organic EL elements as pixels, active matrix flat self-luminous display devices using thin film transistors as driving transistors are actively developed (for example, Patent Documents 1 to 5). reference.). One pixel of this active matrix type flat self-luminous display device includes an organic EL element, a driving transistor made of a thin film transistor, a sampling transistor made of a thin film transistor, and a storage capacitor (pixel capacity). Here, the holding capacitor is for holding an input voltage (a gate voltage of the driving transistor) corresponding to the sampled video signal.

  FIG. 35 shows a structure of a driving transistor and a storage capacitor formed of a thin film transistor included in one pixel. As shown in FIG. 35, in this example, a gate wiring 502 of a driving transistor and one electrode 503 of a storage capacitor are provided on a glass substrate 501 by using a first-layer wiring material. A gate insulating film 504 is provided on the entire surface so as to cover the gate wiring 502 and the electrode 503. Polycrystalline silicon films 505 and 506 having predetermined shapes are provided on the gate insulating film 504 above the driving transistor portion and the storage capacitor portion, respectively. Although illustration is omitted, a source region and a drain region are formed in the polycrystalline silicon film 505 in a self-aligned manner with respect to the gate wiring 502. The gate electrode formed of the gate wiring 502 and the source region and the drain region constitute a bottom gate type polycrystalline silicon thin film transistor as a driving transistor. On the other hand, the polycrystalline Si film 506 is used as an electrode, and a storage capacitor is constituted by a structure in which the gate insulating film 504 is sandwiched between the polycrystalline silicon film 506 and the electrode 503. An interlayer insulating film 507 is provided on the entire surface so as to cover the polycrystalline silicon films 505 and 506. In the interlayer insulating film 507, contact holes 508 and 509 are provided in portions above the source region and the drain region formed in the polycrystalline silicon film 505. Then, through these contact holes 508 and 509, wirings 510 and 511 are formed of the second-layer wiring material.

JP 2003-255856 A JP 2003-271095 A JP 2004-133240 A JP 2004-29791 A JP 2004-93682 A

  In the above active matrix type flat self-luminous display device, when the pixel pitch becomes smaller as the display screen becomes higher in definition, the layout area of the circuit pattern in the pixel is limited. In particular, the storage capacity is determined by the area of the portion where the electrode 503 and the polycrystalline silicon film 506 overlap with each other. However, when the pixel pitch is reduced, this area cannot be secured sufficiently, so that sufficient storage capacity is secured. Can not do it. In addition, when the pixel pitch is reduced, the short-circuit rate between the gate wiring 502 formed of the same wiring material and the electrode 503 is also increased.

Therefore, it is conceivable to reduce the thickness of the gate insulating film 504 used as the dielectric film of the storage capacitor or change the material of the dielectric film of the storage capacitor. Since the performance of the driving transistor is also determined, there is a problem that the characteristics of the driving transistor are changed. This is because the drain current of a general MOS transistor is
I _ds = (1/2) μ (W / L) C _ox (V _gs −V _th ) ² (1)
It is because it is represented by. Here, I _ds is the drain current, μ is the carrier mobility of the channel region, W is the channel width, L is the channel length, C _ox is the gate capacitance, and V _gs is the gate-source voltage (applied to the gate with reference to the source). Gate voltage), V _th is a threshold voltage. Further, when the thickness of the gate insulating film 504 is reduced, the gate capacitance C _ox is increased and the drain current I _ds is increased, but the transistor breakdown voltage tends to be lowered.
Therefore, the problem to be solved by the present invention is to provide a display device capable of ensuring a sufficient storage capacity without changing the transistor characteristics of a driving transistor including a thin film transistor included in a pixel, a driving method thereof, and such an excellent feature. It is to provide an electronic device using the display device.

  On the other hand, in a conventional active matrix type flat self-luminous display device, a pixel crosses a scanning line arranged in a row supplying a control signal and a signal line arranged in a column supplying a video signal. It is disposed in the portion and includes at least a sampling transistor, a storage capacitor, a driving transistor, and a light emitting element. The sampling transistor is turned on according to the control signal supplied from the scanning line, and samples the video signal supplied from the signal line. The holding capacitor holds an input voltage corresponding to the sampled video signal. The driving transistor supplies an output current during a predetermined light emission period in accordance with the input voltage held by the holding capacitor. In general, the output current depends on the carrier mobility and threshold voltage of the channel region of the driving transistor. The light emitting element emits light with luminance according to the video signal by the output current supplied from the driving transistor. In the driving transistor, the input voltage held by the holding capacitor is applied to the gate, an output current flows between the source and the drain, and the light emitting element is energized. In general, the light emission luminance of a light emitting element is proportional to the amount of current applied. Further, the output current supply amount of the driving transistor is controlled by the gate voltage, that is, the input voltage written in the storage capacitor. In the conventional pixel, the amount of current supplied to the light emitting element is controlled by changing the input voltage applied to the gate of the driving transistor in accordance with the input video signal.

Here, as described above, the operating characteristic of the driving transistor is expressed by the equation (1). The drain current I _{ds of the} equation (1) is an output current supplied to the light emitting element in the pixel. is there. The gate voltage V _gs is the above-described input voltage in the pixel. As apparent from the equation (1), when the thin film transistor operates in the saturation region, when the gate voltage V _gs exceeds the threshold voltage V _th , the thin film transistor is turned on and the drain current I _ds flows. Considering in principle, as shown in the equation (1), if the gate voltage V _gs is constant, the same amount of drain current I _ds is always supplied to the light emitting element. Therefore, if video signals of the same level are supplied to all the pixels constituting the screen, all the pixels should emit light with the same luminance, and the uniformity of the screen should be obtained. However, in practice, thin film transistors made of semiconductor thin films such as polycrystalline silicon have variations in individual characteristics. In particular, the threshold voltage V _th is not constant and varies from pixel to pixel. As apparent from the equation (1), when the threshold voltage V _th of each driving transistor varies, even if the gate voltage V _gs is constant, the drain current I _ds varies, and the luminance is different for each pixel. Since it varies, the uniformity of the screen is damaged. In view of this, a pixel incorporating a function (threshold voltage correction function) for canceling variation in the threshold voltage _Vth of the driving transistor has been developed (see, for example, Patent Document 3). However, a display device incorporating such a threshold voltage correction function in a pixel has a complicated structure, which has been an obstacle to pixel miniaturization or display screen high definition. In addition, a pixel incorporating a conventional threshold voltage correction function is not efficient and complicates circuit design. In addition, a pixel having a conventional threshold voltage correction function has a relatively large number of constituent elements, which causes a reduction in the yield of the display device.

Accordingly, another problem to be solved by the present invention is to improve the efficiency and simplification of a pixel having a threshold voltage correction function, thereby improving the definition of the display screen and improving the yield. To provide a display device, a driving method thereof, and an electronic apparatus using such an excellent display device.
The above and other problems of the present invention will become apparent from the description of this specification with reference to the accompanying drawings.

In order to solve the above problem, the first invention is:
A pixel array unit, a scanner unit, and a signal unit;
The pixel array unit includes a scanning line arranged in a row, a signal line arranged in a column, and a matrix pixel arranged in a portion where the scanning line and the signal line intersect,
The signal unit supplies a video signal to the signal line,
The scanner unit supplies a control signal to the first scanning line and the second scanning line to sequentially scan the pixels for each row,
The pixel includes a light emitting element, a sampling transistor made of a thin film transistor, a drive transistor made of a thin film transistor, a storage capacitor, and a switching transistor for connecting the drive transistor to a power source,
The sampling transistor is turned on in response to a control signal supplied from the first scanning line, samples the signal potential of the video signal supplied from the signal line in the holding capacitor,
The holding capacitor applies an input voltage to the gate of the driving transistor according to the signal potential of the sampled video signal,
The driving transistor supplies an output current corresponding to the input voltage to the light emitting element, and the output current has a dependency on a threshold voltage of the driving transistor,
The light emitting element emits light with a luminance corresponding to the signal potential of the video signal by an output current supplied from the driving transistor during a light emission period,
The switching transistor is turned on in response to a control signal supplied from the second scanning line, connects the driving transistor to a power source during the light emission period, and becomes non-conductive during the non-light emission period. Disconnect from the power supply,
The scanner unit outputs a control signal to the first scanning line and the second scanning line in a horizontal scanning period, controls on / off of the sampling transistor and the switching transistor, and controls the threshold of the output current. Preparation operation for resetting the storage capacitor to correct the dependency on the value voltage, correction operation for writing a voltage for canceling the threshold voltage to the reset storage capacitor, and the corrected storage capacitor A display device configured to perform a sampling operation for sampling the signal potential of the video signal,
The gate insulating film of the driving transistor and the dielectric film constituting the storage capacitor are formed independently of each other.

The second invention is
A pixel array unit, a scanner unit, and a signal unit;
The pixel array unit includes a scanning line arranged in a row, a signal line arranged in a column, and a matrix pixel arranged in a portion where the scanning line and the signal line intersect,
The signal unit supplies a video signal to the signal line,
The scanner unit supplies a control signal to the first scanning line and the second scanning line to sequentially scan the pixels for each row,
The pixel includes a light emitting element, a sampling transistor made of a thin film transistor, a drive transistor made of a thin film transistor, a storage capacitor, and a switching transistor for connecting the drive transistor to a power source,
A driving method of a display device in which a gate insulating film of the driving transistor and a dielectric film constituting the storage capacitor are formed independently of each other,
The sampling transistor is turned on in response to a control signal supplied from the first scanning line, and samples the signal potential of the video signal supplied from the signal line in the storage capacitor;
The holding capacitor applies an input voltage to the gate of the driving transistor according to the signal potential of the sampled video signal,
The driving transistor supplies an output current corresponding to the input voltage to the light emitting element, and the output current has a dependency on a threshold voltage of the driving transistor,
The light emitting element emits light with a luminance corresponding to the signal potential of the video signal by an output current supplied from the driving transistor during a light emission period,
The switching transistor is turned on in response to a control signal supplied from the second scanning line, connects the driving transistor to a power source during the light emission period, and becomes non-conductive during the non-light emission period. Disconnect from the power supply,
The scanner unit outputs a control signal to the first scanning line and the second scanning line in a horizontal scanning period, controls on / off of the sampling transistor and the switching transistor, and controls the threshold of the output current. Preparation operation for resetting the storage capacitor to correct the dependency on the value voltage, correction operation for writing a voltage for canceling the threshold voltage to the reset storage capacitor, and the corrected storage capacitor In addition, a sampling operation for sampling the signal potential of the video signal is executed.

  In the first and second aspects of the invention, typically, for example, the signal unit switches the video signal between the first fixed potential, the second fixed potential, and the signal potential during the horizontal scanning period, thereby preparing operation. A potential necessary for the correction operation and the sampling operation is supplied to each pixel through a signal line. Similarly, the signal unit, for example, first supplies a first fixed potential at a high level, then switches to a second fixed potential at a low level to enable a preparatory operation, and further maintains the second fixed potential at a low level. The correction operation is executed in the state, and then the sampling operation is executed by switching to the signal potential. The signal unit, for example, inserts the first fixed potential and the second fixed potential into the signal generation circuit that generates the signal potential and the signal potential output from the signal generation circuit. And an output circuit that synthesizes a video signal in which the fixed potential and the signal potential are switched and outputs the synthesized video signal to the signal line. The signal unit outputs, for example, a video signal obtained by synthesizing a signal potential that does not exceed a normal rating and a first fixed potential that exceeds the rating, and the signal generation circuit normally generates a signal potential that does not exceed the rating. The output circuit has a high breakdown voltage to cope with the first fixed potential exceeding the rating. Further, for example, the output current of the driving transistor has a dependency on the carrier mobility of the channel region in addition to the threshold voltage, and the scanner unit applies the second scanning line during the horizontal scanning period. In order to further control the switching transistor by outputting a control signal and cancel the dependence of the output current on the carrier mobility, the output current is extracted from the driving transistor while the signal potential is sampled, and this output current is held. An operation of correcting the input voltage by performing negative feedback to the capacitor is performed.

The third invention is
A pixel array unit, a scanner unit, and a drive unit;
The pixel array unit includes a scanning line arranged in a row, a signal line arranged in a column, and a matrix pixel arranged in a portion where the scanning line and the signal line intersect,
The driving unit supplies a video signal to the signal line,
The scanner unit supplies a control signal to the first scanning line and the second scanning line to sequentially scan the pixels for each row,
The pixel includes a light emitting element, a sampling transistor made of a thin film transistor, a drive transistor made of a thin film transistor, a storage capacitor, and a switching transistor for connecting the drive transistor to a power source,
The sampling transistor is turned on in response to a control signal supplied from the first scanning line, and samples the signal potential of the video signal supplied from the signal line in the holding capacitor,
The holding capacitor applies an input voltage to the gate of the driving transistor according to the signal potential of the sampled video signal,
The driving transistor supplies an output current corresponding to the input voltage to the light emitting element,
The light emitting element emits light with a luminance corresponding to the signal potential of the video signal by an output current supplied from the driving transistor during a light emission period,
The switching transistor is turned on in response to a control signal supplied from the second scan line, connects the driving transistor to a power source during the light emission period, and becomes non-conductive during a non-light emission period, Disconnect the transistor from the power supply,
The scanner unit outputs a control signal to the first scanning line and the second scanning line, respectively, during a horizontal scanning period, and controls on / off of the sampling transistor and the switching transistor, thereby varying the output current. Perform a correction operation to correct and a sampling operation to sample the signal potential of the video signal,
The driver unit switches the video signal between a fixed potential and a signal potential during the horizontal scanning period, and thereby supplies a potential necessary for the correction operation and the sampling operation to the pixel via the signal line. A display device configured as follows:
The gate insulating film of the driving transistor and the dielectric film constituting the storage capacitor are formed independently of each other.

  In the third invention, for example, the drive unit inserts a fixed potential into the signal generation circuit that generates the signal potential and the signal potential output from the signal generation circuit, whereby the fixed potential and the signal potential are And an output circuit that synthesizes the video signals to be switched and outputs them to each signal line. For example, the drive unit outputs a video signal that combines a signal potential that does not exceed the normal rating and a fixed potential that exceeds the rating, and the signal generation circuit generates a signal potential that does not exceed the rating. Only the output circuit has a high breakdown voltage to cope with a fixed potential exceeding the rating.

The fourth invention is:
Including a pixel array unit and a drive unit,
The pixel array section corresponds to a scanning line arranged in a row, a signal line arranged in a column, a matrix pixel arranged in a portion where the scanning line and the signal line intersect, and each row of the pixel. Power line arranged
The driving unit supplies a control signal to the scanning lines sequentially to scan the pixels line-by-line in units of rows, and applies a first potential and a second potential to the power supply line in accordance with the line sequential scanning. A power supply scanner that supplies a power supply voltage that is switched between, and a signal selector that supplies a signal potential and a reference potential to be a video signal to the signal line in accordance with the line sequential scanning,
The pixel includes a light emitting element, a sampling transistor including a thin film transistor, a driving transistor including a thin film transistor, and a storage capacitor.
The sampling transistor has its gate connected to the scanning line, one of its source and drain connected to the signal line, and the other connected to the gate of the driving transistor,
The driving transistor has one of a source and a drain connected to the light emitting element, the other connected to the power supply line,
The storage capacitor is connected between a source and a gate of the driving transistor,
The sampling transistor is turned on in response to a control signal supplied from the scanning line, samples the signal potential supplied from the signal line, and holds it in the storage capacitor,
The driving transistor receives a supply of current from the power supply line at the first potential, and causes a driving current to flow to the light emitting element according to the held signal potential.
The power supply scanner switches the power supply line between the first potential and the second potential while the signal selector supplies a reference potential to the signal line after the sampling transistor is turned on. The display device is configured to hold a voltage corresponding to the threshold voltage of the driving transistor in the holding capacitor.
The gate insulating film of the driving transistor and the dielectric film constituting the storage capacitor are formed independently of each other.

The fifth invention is:
Including a pixel array unit and a drive unit,
The pixel array section corresponds to a scanning line arranged in a row, a signal line arranged in a column, a matrix pixel arranged in a portion where the scanning line and the signal line intersect, and each row of the pixel. Power line arranged
The driving unit supplies a control signal to the scanning lines sequentially to scan the pixels line by line, and the power supply line is supplied with a first potential and a second potential in accordance with the line sequential scanning. A power supply scanner that supplies a power supply voltage that is switched between, and a signal selector that supplies a signal potential and a reference potential to be a video signal to the signal line in accordance with the line sequential scanning,
The pixel includes a light emitting element, a sampling transistor including a thin film transistor, a driving transistor including a thin film transistor, and a storage capacitor.
The sampling transistor has its gate connected to the scanning line, one of its source and drain connected to the signal line, and the other connected to the gate of the driving transistor,
The driving transistor has one of a source and a drain connected to the light emitting element, the other connected to the power supply line,
The storage capacitor is connected between the source and gate of the driving transistor,
A driving method of a display device in which a gate insulating film of the driving transistor and a dielectric film constituting the storage capacitor are formed independently of each other,
The sampling transistor is turned on in response to a control signal supplied from the scanning line, samples the signal potential supplied from the signal line, and holds it in the storage capacitor;
The driving transistor receives a current supplied from the power supply line at the first potential, and causes a driving current to flow to the light emitting element in accordance with the held signal potential;
The power supply scanner switches the power supply line between the first potential and the second potential while the signal selector supplies a reference potential to the signal line after the sampling transistor is turned on. Thus, a voltage corresponding to the threshold voltage of the driving transistor is held in the holding capacitor.

  In the fourth and fifth inventions, typically, for example, the signal selector switches the signal line from the reference potential to the signal potential at the first timing after the sampling transistor is turned on, and the main scanner By canceling the application of the control signal to the scanning line at the second timing after the timing to make the sampling transistor non-conductive, and appropriately setting the period between the first timing and the second timing, When the signal potential is held in the storage capacitor, a correction for the carrier mobility in the channel region of the driving transistor is added to the signal potential. Further, the drive unit adjusts the relative phase difference between the video signal supplied from the signal selector and the control signal supplied from the main scanner, for example, and sets a period between the first timing and the second timing. Configured to optimize. The signal selector is configured to, for example, incline the rising edge of the video signal that switches from the reference potential to the signal potential so that the period between the first timing and the second timing follows the signal potential. The The main scanner also cancels the application of the control signal to the scanning line at the stage where the signal potential is held in the holding capacitor, makes the sampling transistor non-conductive, and electrically disconnects the gate of the driving transistor from the signal line. Thus, the voltage between the gate and the source is kept constant in conjunction with the change in the source potential of the driving transistor in conjunction with the gate potential.

The sixth invention is:
Including a pixel array unit and a drive unit,
The pixel array section corresponds to a scanning line arranged in a row, a signal line arranged in a column, a matrix pixel arranged in a portion where the scanning line and the signal line intersect, and each row of the pixel. Power line arranged
The driving unit supplies a control signal to the scanning lines sequentially to scan the pixels line by line, and the power supply line is supplied with a first potential and a second potential in accordance with the line sequential scanning. A power supply scanner that supplies a power supply voltage that is switched between, and a signal selector that supplies a signal potential and a reference potential to be a video signal to the signal line in accordance with the line sequential scanning,
The pixel includes a light emitting element, a sampling transistor including a thin film transistor, a driving transistor including a thin film transistor, and a storage capacitor.
The sampling transistor has its gate connected to the scanning line, one of its source and drain connected to the signal line, and the other connected to the gate of the driving transistor,
The driving transistor has one of a source and a drain connected to the light emitting element, the other connected to the power supply line,
The storage capacitor is connected between a source and a gate of the driving transistor,
The sampling transistor is turned on in response to a control signal supplied from the scanning line, samples the signal potential supplied from the signal line, and holds it in the storage capacitor,
The driving transistor receives a supply of current from the power supply line at the first potential, and causes a driving current to flow to the light emitting element according to the held signal potential,
The signal selector switches the signal line from a reference potential to a signal potential at a first timing after the sampling transistor is turned on,
The main scanner cancels the application of the control signal to the scanning line at the second timing after the first timing to make the sampling transistor non-conductive,
By appropriately setting the period between the first timing and the second timing, when the signal potential is held in the storage capacitor, the correction for the carrier mobility in the channel region of the driving transistor is performed as a signal. A display device configured to apply an electric potential,
The gate insulating film of the driving transistor and the dielectric film constituting the storage capacitor are formed independently of each other.

The seventh invention
Including a pixel array unit and a drive unit,
The pixel array section corresponds to a scanning line arranged in a row, a signal line arranged in a column, a matrix pixel arranged in a portion where the scanning line and the signal line intersect, and each row of the pixel. Power line arranged
The driving unit supplies a control signal to the scanning lines sequentially to scan the pixels line by line, and the power supply line is supplied with a first potential and a second potential in accordance with the line sequential scanning. A power supply scanner that supplies a power supply voltage that is switched between, and a signal selector that supplies a signal potential and a reference potential to be a video signal to the signal line in accordance with the line sequential scanning,
The pixel includes a light emitting element, a sampling transistor including a thin film transistor, a driving transistor including a thin film transistor, and a storage capacitor.
The sampling transistor has its gate connected to the scanning line, one of its source and drain connected to the signal line, and the other connected to the gate of the driving transistor,
The driving transistor has one of a source and a drain connected to the light emitting element, the other connected to the power supply line,
The storage capacitor is connected between the source and gate of the driving transistor,
A driving method of a display device in which a gate insulating film of the driving transistor and a dielectric film constituting the storage capacitor are formed independently of each other,
The sampling transistor is turned on in response to a control signal supplied from the scanning line, samples the signal potential supplied from the signal line, and holds it in the storage capacitor;
The driving transistor receives a current supplied from the power supply line at the first potential, and causes a driving current to flow to the light emitting element in accordance with the held signal potential;
The signal selector switches the signal line from a reference potential to a signal potential at a first timing after the sampling transistor is turned on,
The main scanner cancels the application of the control signal to the scanning line at the second timing after the first timing to make the sampling transistor non-conductive,
By appropriately setting a period between the first timing and the second timing, when the signal potential is held in the storage capacitor, correction for the carrier mobility in the channel region of the driving transistor is performed as a signal. It is characterized by being applied to an electric potential.

  In the sixth and seventh aspects of the invention, typically, for example, the drive unit adjusts the relative phase difference between the video signal supplied from the signal selector and the control signal supplied from the main scanner, and The period between the timing and the second timing is optimized. The signal selector, for example, inclines the rising edge of the video signal that switches from the reference potential to the signal potential at the first timing, and follows the signal potential in the period between the first timing and the second timing. Let Further, the main scanner, for example, cancels the application of the control signal to the main scanning line at the second timing when the signal potential is held in the holding capacitor, makes the sampling transistor non-conductive, and signals the gate of the driving transistor. By electrically disconnecting from the line, the gate potential is interlocked with the variation of the source potential of the driving transistor, and the voltage between the gate and the source is kept constant. Further, the power supply scanner switches the power supply line between the first potential and the second potential while the signal selector supplies the reference potential to the signal line after the sampling transistor is turned on, for example. A voltage corresponding to the threshold voltage of the driving transistor is held in the holding capacitor.

The eighth invention
An active matrix display device in which a pixel includes a light emitting element, a sampling transistor including a thin film transistor, a driving thin film transistor including a thin film transistor, and a storage capacitor,
The gate insulating film of the driving transistor and the dielectric film constituting the storage capacitor are formed independently of each other.
The display device according to the eighth invention includes not only the display devices according to the first, third, fourth and sixth inventions, but also includes a gate insulating film of a driving transistor and a dielectric film constituting a storage capacitor. The display device includes other display devices except that they are formed independently of each other. Further, the driving method of the display device is not limited to the driving method according to the second, fifth and seventh inventions, and other driving methods may be used.

The ninth invention
In an electronic device having one or more display devices,
At least one of the display devices,
A pixel array unit, a scanner unit, and a signal unit;
The pixel array unit includes a scanning line arranged in a row, a signal line arranged in a column, and a matrix pixel arranged in a portion where the scanning line and the signal line intersect,
The signal unit supplies a video signal to the signal line,
The scanner unit supplies a control signal to the first scanning line and the second scanning line to sequentially scan the pixels for each row,
The pixel includes a light emitting element, a sampling transistor made of a thin film transistor, a drive transistor made of a thin film transistor, a storage capacitor, and a switching transistor for connecting the drive transistor to a power source,
The sampling transistor is turned on in response to a control signal supplied from the first scanning line, samples the signal potential of the video signal supplied from the signal line in the holding capacitor,
The holding capacitor applies an input voltage to the gate of the driving transistor according to the signal potential of the sampled video signal,
The driving transistor supplies an output current corresponding to the input voltage to the light emitting element, and the output current has a dependency on a threshold voltage of the driving transistor,
The light emitting element emits light with a luminance corresponding to the signal potential of the video signal by an output current supplied from the driving transistor during a light emission period,
The switching transistor is turned on in response to a control signal supplied from the second scanning line, connects the driving transistor to a power source during the light emission period, and becomes non-conductive during the non-light emission period. Disconnect from the power supply,
The scanner unit outputs a control signal to the first scanning line and the second scanning line in a horizontal scanning period, controls on / off of the sampling transistor and the switching transistor, and controls the threshold of the output current. Preparation operation for resetting the storage capacitor to correct the dependency on the value voltage, correction operation for writing a voltage for canceling the threshold voltage to the reset storage capacitor, and the corrected storage capacitor A display device configured to perform a sampling operation for sampling the signal potential of the video signal,
The gate insulating film of the driving transistor and the dielectric film constituting the storage capacitor are formed independently of each other.
In the ninth aspect, what has been described in relation to the first and second aspects is valid.

The tenth invention is
In an electronic device having one or more display devices,
At least one of the display devices,
A pixel array unit, a scanner unit, and a drive unit;
The pixel array unit includes a scanning line arranged in a row, a signal line arranged in a column, and a matrix pixel arranged in a portion where the scanning line and the signal line intersect,
The driving unit supplies a video signal to the signal line,
The scanner unit supplies a control signal to the first scanning line and the second scanning line to sequentially scan the pixels for each row,
The pixel includes a light emitting element, a sampling transistor made of a thin film transistor, a drive transistor made of a thin film transistor, a storage capacitor, and a switching transistor for connecting the drive transistor to a power source,
The sampling transistor is turned on in response to a control signal supplied from the first scanning line, and samples the signal potential of the video signal supplied from the signal line in the holding capacitor,
The holding capacitor applies an input voltage to the gate of the driving transistor according to the signal potential of the sampled video signal,
The driving transistor supplies an output current corresponding to the input voltage to the light emitting element,
The light emitting element emits light with a luminance corresponding to the signal potential of the video signal by an output current supplied from the driving transistor during a light emission period,
The switching transistor is turned on in response to a control signal supplied from the second scan line, connects the driving transistor to a power source during the light emission period, and becomes non-conductive during a non-light emission period, Disconnect the transistor from the power supply,
The scanner unit outputs a control signal to the first scanning line and the second scanning line, respectively, during a horizontal scanning period, and controls on / off of the sampling transistor and the switching transistor, thereby varying the output current. Perform a correction operation to correct and a sampling operation to sample the signal potential of the video signal,
The driver unit switches the video signal between a fixed potential and a signal potential during the horizontal scanning period, and thereby supplies a potential necessary for the correction operation and the sampling operation to the pixel via the signal line. A display device configured as follows:
The gate insulating film of the driving transistor and the dielectric film constituting the storage capacitor are formed independently of each other.
In the tenth aspect, what has been described in relation to the third aspect is established.

The eleventh invention is
In an electronic device having one or more display devices,
At least one of the display devices,
Including a pixel array unit and a drive unit,
The pixel array section corresponds to a scanning line arranged in a row, a signal line arranged in a column, a matrix pixel arranged in a portion where the scanning line and the signal line intersect, and each row of the pixel. Power line arranged
The driving unit supplies a control signal to the scanning lines sequentially to scan the pixels line by line, and the power supply line is supplied with a first potential and a second potential in accordance with the line sequential scanning. A power supply scanner that supplies a power supply voltage that is switched between, and a signal selector that supplies a signal potential and a reference potential to be a video signal to the signal line in accordance with the line sequential scanning,
The pixel includes a light emitting element, a sampling transistor including a thin film transistor, a driving transistor including a thin film transistor, and a storage capacitor.
The sampling transistor has its gate connected to the scanning line, one of its source and drain connected to the signal line, and the other connected to the gate of the driving transistor,
The driving transistor has one of a source and a drain connected to the light emitting element, the other connected to the power supply line,
The storage capacitor is connected between a source and a gate of the driving transistor,
The sampling transistor is turned on in response to a control signal supplied from the scanning line, samples the signal potential supplied from the signal line, and holds it in the storage capacitor,
The driving transistor receives a supply of current from the power supply line at the first potential, and causes a driving current to flow to the light emitting element according to the held signal potential,
The signal selector switches the signal line from a reference potential to a signal potential at a first timing after the sampling transistor is turned on,
The main scanner cancels the application of the control signal to the scanning line at the second timing after the first timing to make the sampling transistor non-conductive,
By appropriately setting the period between the first timing and the second timing, when the signal potential is held in the storage capacitor, the correction for the carrier mobility in the channel region of the driving transistor is performed as a signal. A display device configured to apply an electric potential,
The gate insulating film of the driving transistor and the dielectric film constituting the storage capacitor are formed independently of each other.
In the eleventh aspect, what has been described in relation to the fourth and fifth aspects is established.

The twelfth invention
In an electronic device having one or more display devices,
At least one of the display devices,
Including a pixel array unit and a drive unit,
The pixel array section corresponds to a scanning line arranged in a row, a signal line arranged in a column, a matrix pixel arranged in a portion where the scanning line and the signal line intersect, and each row of the pixel. Power line arranged
The driving unit supplies a control signal to the scanning lines sequentially to scan the pixels line by line, and the power supply line is supplied with a first potential and a second potential in accordance with the line sequential scanning. A power supply scanner that supplies a power supply voltage that is switched between, and a signal selector that supplies a signal potential and a reference potential to be a video signal to the signal line in accordance with the line sequential scanning,
The pixel includes a light emitting element, a sampling transistor including a thin film transistor, a driving transistor including a thin film transistor, and a storage capacitor.
The sampling transistor has its gate connected to the scanning line, one of its source and drain connected to the signal line, and the other connected to the gate of the driving transistor,
The driving transistor has one of a source and a drain connected to the light emitting element, the other connected to the power supply line,
The storage capacitor is connected between a source and a gate of the driving transistor,
The sampling transistor is turned on in response to a control signal supplied from the scanning line, samples the signal potential supplied from the signal line, and holds it in the storage capacitor,
The driving transistor receives a supply of current from the power supply line at the first potential, and causes a driving current to flow to the light emitting element according to the held signal potential,
The signal selector switches the signal line from a reference potential to a signal potential at a first timing after the sampling transistor is turned on,
The main scanner cancels the application of the control signal to the scanning line at the second timing after the first timing to make the sampling transistor non-conductive,
By appropriately setting the period between the first timing and the second timing, when the signal potential is held in the storage capacitor, the correction for the carrier mobility in the channel region of the driving transistor is performed as a signal. A display device configured to apply an electric potential,
The gate insulating film of the driving transistor and the dielectric film constituting the storage capacitor are formed independently of each other.
In the twelfth aspect, what has been described in relation to the sixth and seventh aspects is established.

  In the ninth to twelfth inventions, various electronic devices are included. For example, the electronic devices are input to an electronic device such as a flat-screen TV, a digital camera, a notebook personal computer, a cellular phone, a video camera, or the electronic device. This includes electronic devices in all fields that display video signals generated in the form of images or videos. For example, in a thin television including a video display screen composed of a front panel, filter glass, and the like, a display device is used for the video display screen. Further, in a digital camera including an imaging lens, a flash light emitting unit, a display unit, a control switch, a menu switch, a shutter, and the like, a display device is used for the display unit. In a notebook personal computer including a display unit for displaying an image, a display device is used for the display unit. Further, in a mobile phone including an upper housing, a lower housing, a connecting portion (such as a hinge portion), a display, a sub display, a picture light, and a camera, a display device is used for the display and the sub display. Further, in a video camera including a main body, a lens for photographing a subject provided on a side facing the front, a start / stop switch at the time of photographing, a display unit, a display device is used for the display unit.

In the first to twelfth inventions, as the thin film transistors constituting the driving transistor, the sampling transistor, and the switching transistor, those using various semiconductor thin films such as a silicon film and a ZnO film can be used. Further, the crystallinity of the semiconductor thin film may be any of single crystal, polycrystalline, microcrystalline, and amorphous. Moreover, as a light emitting element, you may use a light emitting diode other than an organic EL element. A material and a structure used for the light-emitting element are not particularly limited and are appropriately selected.
In the first to twelfth inventions, the display device includes a module shape, for example, a display module formed by pasting the pixel array portion to a transparent facing portion such as glass. . This display module may be provided with a flexible printed circuit (FPC) for inputting / outputting a signal to / from the pixel array portion from the outside.

  In the first to twelfth inventions configured as described above, in the pixel of the display device, the gate insulating film of the driving transistor and the dielectric film forming the storage capacitor are formed independently of each other. The gate insulating film of the driving transistor and the dielectric film constituting the storage capacitor can be optimally designed. In other words, the gate insulating film of the driving transistor can be made of a material and thickness optimal for the driving transistor, and the dielectric film constituting the storage capacitor can be used in the layout area of the circuit pattern in the pixel. Accordingly, an optimum material and thickness can be used so as to ensure a sufficient holding capacity.

  According to the present invention, a sufficient storage capacity can be ensured without changing the transistor characteristics of the driving transistor formed of the thin film transistor included in the pixel of the display device, so that a good image can be displayed. In addition, since the area of the storage capacitor can be sufficiently reduced even when the pixel pitch is reduced, it is possible to suppress an increase in the short-circuit ratio between the wiring and the electrode formed with the same wiring material. .

  According to the first to third inventions, the display device has a threshold voltage correction function for each pixel, and is based on gate potential coupling within one horizontal scanning period (1H) assigned to each row of pixels. By performing the threshold voltage correction preparatory operation, the actual threshold voltage correction operation, and the signal voltage sampling operation, the number of elements constituting each pixel is emitted by three transistors and one capacitor. The number of elements can be reduced to one. For this reason, it is possible to improve the yield of the display device by reducing the number of power supply lines and gate wirings (scanning lines) and greatly reducing the crossover between the wirings. At the same time, it is possible to increase the definition of the display device. Furthermore, not only sampling scanning but also correction operation is executed within the horizontal scanning period, so that a fixed potential for control is supplied from the signal line in addition to the signal potential. As described above, the display device can supply not only image data but also a fixed voltage for pixel control to the pixel array from the data signal line. As a result, the means for correcting the characteristic variation of the driving transistor included in each pixel can be configured with a small number of elements. Further, even if the fixed voltage for pixel control is higher than the maximum rated voltage of a general driver IC, it is only necessary to increase the breakdown voltage of the output circuit unit, and it is not necessary to increase the breakdown voltage of the driver IC. It is possible to prevent an increase in the cost of the IC due to an increase in the physical size of the driver, such as an increase in size and a wide pitch, and to cope with a high-resolution display device.

  According to the fourth to seventh inventions, the display device has a threshold voltage correction function, a mobility correction function, a bootstrap function, etc. for each pixel. Threshold voltage fluctuations can be corrected, the mobility correction function can also correct the mobility fluctuations of the driving transistor, and the bootstrap operation of the storage capacitor at the time of light emission can emit light from an organic EL element or the like. Regardless of variations in the characteristics of the element, it is possible to always maintain a constant light emission luminance. In other words, even if the current-voltage characteristics of light-emitting elements such as organic EL elements fluctuate over time, the gate-source voltage of the driving transistor is kept constant by the bootstrap storage capacitor, so that the light emission luminance is kept constant. can do. In addition, since the above-described threshold voltage correction function, mobility correction function, bootstrap operation, and the like are incorporated in each pixel of the display device, the power supply voltage supplied to each pixel can be used as a switching pulse. By using the switching pulse, the switching transistor for correcting the threshold voltage and the scanning line for controlling the gate thereof become unnecessary. As a result, the constituent elements and wirings of the pixel can be greatly reduced, the area of the pixel can be reduced, and the screen of the display device can be increased in definition. Further, by performing the mobility correction simultaneously with the sampling of the video signal potential, the mobility correction period can be adjusted by the phase difference between the video signal and the sampling pulse. Furthermore, the mobility correction period can automatically follow the level of the video signal. In addition, since the number of constituent elements of the pixel is small, the parasitic capacitance at the gate of the driving transistor is reduced, so that the bootstrap operation can be performed with certainty, and the ability to correct changes with time of light-emitting elements such as organic EL elements can be achieved. Can be improved.

In addition, each pixel of the display device has a threshold voltage correction function and a mobility correction function of the driving transistor and a temporal variation correction function (bootstrap operation) of the light emitting element, so that high-quality image quality can be obtained. In particular, with regard to mobility correction, an appropriate correction period can be automatically set following the video signal potential, so that mobility correction can be performed regardless of the brightness or the pattern of the image. Conventionally, a pixel having such a correction function has a large layout area due to the large number of constituent elements, and is not suitable for high definition of the screen of the display device. In this display device, however, the power supply voltage is switched. Thus, the number of constituent elements and wirings of the pixel can be reduced, and the layout area of the pixel can be reduced.
As described above, a high-quality and high-definition active matrix self-luminous display device can be provided.
According to the ninth to twelfth inventions, various electronic devices having excellent display performance can be realized by using the excellent display device as described above.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, referring to FIG. 1, an outline of a reference example of an active matrix display device that is the basis of an active matrix display device according to the following embodiment in terms of the circuit will be described.
As shown in FIG. 1, the active matrix display device is composed of a pixel array section 1 and a peripheral circuit section as main parts. The peripheral circuit section includes a horizontal selector 3, a write scanner 4, a drive scanner 5, a first correction scanner 71, a second correction scanner 72, and the like. The pixel array section 1 is composed of scanning lines WS arranged in rows, signal lines SL arranged in columns, and pixels 2 arranged in a matrix at the intersection of both. However, in FIG. 1, only one pixel 2 is enlarged for easy understanding. The signal line SL is driven by the horizontal selector 3. The horizontal selector 3 forms a signal unit and supplies a video signal to the signal line SL. The scanning line WS is scanned by the write scanner 4. In addition, other scanning lines DS, AZ1 and AZ2 are also wired in parallel with the scanning line WS. The scanning line DS is scanned by the drive scanner 5. The scanning line AZ1 is scanned by the first correction scanner 71. The scanning line AZ2 is scanned by the second correction scanner 72. The write scanner 4, the drive scanner 5, the first correction scanner 71, and the second correction scanner 72 constitute a scanner unit, which sequentially scans a row of pixels every horizontal scanning period. Each pixel 2 samples a video signal from the signal line SL when selected by the scanning line WS. Further, when selected by the scanning line DS, the light emitting element EL included in the pixel 2 is driven in accordance with the sampled video signal. In addition, the pixel 2 performs a predetermined correction operation when scanned by the scanning lines AZ1 and AZ2.

The pixel 2 includes five transistors Tr1 to Tr4 and Trd made of thin film transistors, a storage capacitor (pixel capacity) C _{s made} of one capacitor, and one light emitting element EL. The transistors Tr1 to Tr3 and Trd are, for example, n-channel polycrystalline silicon thin film transistors, but are not limited thereto. Only the transistor Tr4 is a p-channel polycrystalline silicon thin film transistor. The light emitting element EL is, for example, a diode type organic EL element having an anode and a cathode, but is not limited to this, and generally includes all light emitting elements that emit light by current drive.

The driving transistor Trd which is the center of the pixel 2 has a gate G is connected to one end of the storage capacitor C _s, the source S is also connected to the other end of the storage capacitor C _s. The gate G of the driving transistor Trd is connected to another reference potential V _ss1 via the switching transistor Tr2. The drain of the driving transistor Trd is connected to the power source _Vcc via the switching transistor Tr4. The gate of the switching transistor Tr2 is connected to the scanning line AZ1. The gate of the switching transistor Tr4 is connected to the scanning line DS. The anode of the light emitting element EL is connected to the source S of the driving transistor Trd, and the cathode is grounded. This ground potential may be expressed as V _cath . Further, the switching transistor Tr3 is interposed between the source S of the driving transistor Trd and a predetermined reference potential V _ss2 . The gate of the switching transistor Tr3 is connected to the scanning line AZ2. On the other hand, the sampling transistor Tr1 is connected between the signal line SL and the gate G of the drive transistor Trd. The gate of the sampling transistor Tr1 is connected to the scanning line WS.

In the display device configured as described above, the sampling transistor Tr1 is turned on in response to the control signal WS supplied from the scanning line WS in a predetermined sampling period, and the video signal V _sig supplied from the signal line SL is received. Sampling to the holding capacitor C _s . The storage capacitor C _s applies an input voltage V _gs between the gate G and the source S of the driving transistor in accordance with the sampled video signal V _sig . The driving transistor Trd supplies an output current I _ds corresponding to the input voltage V _gs to the light emitting element EL during a predetermined light emission period. This output current (drain current) I _ds has dependence on the carrier mobility μ and the threshold voltage V _{th in} the channel region of the driving transistor Trd. The light emitting element EL emits light with luminance according to the video signal V _sig by the output current I _ds supplied from the driving transistor Trd.

As a feature of this reference example, the pixel 2 is provided with a correction unit including switching transistors Tr2 to Tr4, and is held in advance at the beginning of the light emission period in order to cancel the dependence of the output current I _{ds on} the carrier mobility μ. The input voltage V _gs held in the capacitor C _s is corrected. Specifically, the correction means (Tr2 to Tr4) operate during a part of the sampling period according to the control signals WS and DS supplied from the scanning lines WS and DS, and the video signal V _sig is sampled. In this state, the output current I _ds is taken out from the driving transistor Trd, and this is negatively fed back to the holding capacitor C _s to correct the input voltage V _gs . Further, this correction means (Tr2~Tr4), in order to cancel the dependence on the threshold voltage V _th of the output current I _ds, detects the threshold voltage V _th of the driving transistor Trd prior to advance the sampling period In addition, the detected threshold voltage V _th is added to the input voltage V _gs .

In the case of this reference example, the driving transistor Trd is an n-channel transistor, the drain is connected to the power supply _Vcc side, and the source S is connected to the light emitting element EL side. In this case, the above-described correction means takes out the output current I _ds from the driving transistor Trd at the head part of the light emission period that overlaps the latter part of the sampling period, and negatively feeds back to the holding capacitor C _s side. At this time, the correcting means causes the output current I _ds extracted from the source S side of the driving transistor Trd at the beginning of the light emission period to flow into the capacitance of the light emitting element EL. Specifically, the light-emitting element EL is a diode-type light-emitting element having an anode and a cathode as described above. The anode side is connected to the source S of the driving transistor Trd, and the cathode side is grounded. With this configuration, the correction means (Tr2 to Tr4) sets the anode / cathode of the light emitting element EL in a reverse bias state in advance, and the output current I _ds extracted from the source S side of the driving transistor Trd emits light. When flowing into the element EL, this diode type light emitting element EL is made to function as a capacitive element. This correcting means can adjust the time width t for extracting the output current I _ds from the driving transistor Trd within the sampling period, thereby optimizing the negative feedback amount of the output current I _ds with respect to the holding capacitor C _s . Yes.

FIG. 2 is a schematic diagram of one pixel portion extracted from the display device shown in FIG. In order to facilitate understanding, the video signal V _sig sampled by the driving transistor Tr1, the input voltage V _gs and output current I _{ds of} the driving transistor Trd, and the capacitance component C _oled of the light emitting element EL are written. In addition. Hereinafter, the operation of the pixel 2 of the reference example will be described with reference to FIG.

  FIG. 3 is a timing chart showing the operation of the pixel shown in FIG. With reference to FIG. 3, the operation of the pixel of the reference example shown in FIG. 2 will be described more specifically. In FIG. 3, the waveform of the control signal applied to each scanning line WS, AZ1, AZ2, and DS along the time axis T is shown. In order to simplify the notation, the control signals are also represented by the same reference numerals as the corresponding scanning lines. Since the transistors Tr1, Tr2, and Tr3 are n-channel type, they are turned on when the scanning lines WS, AZ1, and AZ2 are each at a high level and turned off when the scanning lines are at a low level. On the other hand, since the transistor Tr4 is a p-channel type, it is turned off when the scanning line DS is at a high level and turned on when it is at a low level. In this timing chart, the change in the potential of the gate G of the drive transistor Trd and the change in the potential of the source S are also shown along with the waveforms of the control signals WS, AZ1, AZ2, and DS.

  In the timing chart of FIG. 3, timings T1 to T8 are defined as one field (1f). Each row of the pixel array unit 1 is sequentially scanned once during one field. In this timing chart, the waveforms of the control signals WS, AZ1, AZ2, and DS applied to the pixels for one row are shown.

All control lines WS, AZ1, AZ2, and DS are at a low level at timing T0 before the field starts. Therefore, the n-channel transistors Tr1, Tr2, and Tr3 are in the off state, while only the p-channel transistor Tr4 is in the on state. For this reason, since the driving transistor Trd is connected to the power supply _Vcc via the transistor Tr4 in the on state, the output current _Ids is supplied to the light emitting element EL according to the predetermined input voltage _Vgs . As a result, the light emitting element EL emits light at the timing T0. At this time, the input voltage V _gs applied to the driving transistor Trd is represented by the difference between the gate potential (G) and the source potential (S).

At the timing T1 when the field starts, the control signal DS is switched from the low level to the high level. As a result, the transistor Tr4 is turned off, and the driving transistor Trd is disconnected from the power source _Vcc, so that the light emission stops and the non-light emission period starts. Therefore, at the timing T1, all the transistors Tr1 to Tr4 are turned off.

Subsequently, at timing T2, the control signals AZ1 and AZ2 become high level, so that the switching transistors Tr2 and Tr3 are turned on. As a result, the gate G of the driving transistor Trd is connected to the reference potential V _ss1 , and the source S is connected to the reference potential V _ss2 . Here, V _ss1 −V _ss2 > V _th is satisfied, and by _setting V _ss1 −V _ss2 = V _gs > V _th , preparation for V _th correction performed thereafter at timing T3 is performed. In other words, the period T2-T3 corresponds to a reset period of the driving transistor Trd. Further, if the threshold voltage of the light emitting element EL is V _thEL , V _thEL > V _ss2 is set. Thereby, a minus bias is applied to the light emitting element EL, and a so-called reverse bias state is obtained. This reverse bias state is necessary for normal V _th correction operation and mobility correction operation to be performed later.

At timing T3, the control signal AZ2 is set to the low level, and the control signal DS is also set to the low level. Thereby, the transistor Tr3 is turned off while the transistor Tr4 is turned on. As a result, the drain current I _ds flows into the storage capacitor C _s and the V _th correction operation is started. At this time, the potential of the gate G of the driving transistor Trd is held at V _ss1 , and the current I _ds flows until the driving transistor Trd is cut off. When cut off, the source potential (S) of the driving transistor Trd becomes V _ss1 −V _th . At timing T4 after the drain current is cut off, the control signal DS is returned to the high level again, and the switching transistor Tr4 is turned off. Further, the control signal AZ1 is also returned to the low level, and the switching transistor Tr2 is also turned off. As a result, V _th is held fixed to the holding capacitor C _s. Thus, the timing T3-T4 is a period for detecting the threshold voltage _Vth of the driving transistor Trd. Here, this detection period T3-T4 is called a _Vth correction period.

After performing the _Vth correction in this way, the control signal WS is switched to the high level at the timing T5, the sampling transistor Tr1 is turned on, and the video signal V _sig is written in the holding capacitor C _s . The holding capacity C _s is sufficiently smaller than the equivalent capacity C _oled of the light emitting element EL. As a result, most of the video signal V _sig is written in the storage capacitor C _s . More precisely, a difference V _sig −V _ss1 of V _sig with respect to V _ss1 is written in the storage capacitor C _s . Therefore, the voltage V _gs between the gate G and the source S of the driving transistor Trd is a level (V _sig −V _ss1 + V) _obtained by adding V _th previously detected and held and V _sig −V _ss1 sampled this time. _th ). In the following, for ease of explanation, when V _ss1 = 0V, the gate / source voltage V _gs becomes V _sig + V _{th as} shown in the timing chart of FIG. The sampling of the video signal V _sig is performed until timing T7 when the control signal WS returns to the low level. That is, timing T5-T7 corresponds to a sampling period.

At timing T6 before the end of the sampling period T7, the control signal DS becomes low level and the switching transistor Tr4 is turned on. As a result, the driving transistor Trd is connected to the power supply _Vcc , so that the pixel 2 proceeds from the non-light emitting period to the light emitting period. As described above, the mobility of the driving transistor Trd is corrected in the period T6-T7 in which the sampling transistor Tr1 is still in the on state and the switching transistor Tr4 is in the on state. That is, in this reference example, the mobility correction is performed in the period T6-T7 in which the rear part of the sampling period and the head part of the light emission period overlap. Note that, at the beginning of the light emission period in which the mobility correction is performed, the light emitting element EL is actually in a reverse bias state, and thus does not emit light. In the mobility correction period T6-T7, the drain current _Ids flows through the driving transistor Trd in a state where the gate G of the driving transistor Trd is fixed at the level of the video signal _Vsig . Here, by setting V _ss1 −V _th <V _thEL , the light emitting element EL is placed in a reverse bias state, and thus exhibits simple capacitance characteristics instead of diode characteristics. For this reason, the current I _ds flowing through the driving transistor Trd is written into a capacitance C = C _s + C _{oled obtained} by combining both the holding capacitance C _s and the equivalent capacitance C _oled of the light emitting element EL. As a result, the source potential (S) of the drive transistor Trd increases. In the timing chart of FIG. 3, this increase is represented by ΔV. This increase ΔV is eventually subtracted from the gate / source voltage V _gs held in the holding capacitor C _s , so negative feedback is applied. In this way, the mobility μ can be corrected by negatively feeding back the output current I _ds of the driving transistor Trd to the input voltage V _gs of the driving transistor Trd. Note that the negative feedback amount ΔV can be optimized by adjusting the time width t of the mobility correction period T6-T7.

At timing T7, the control signal WS becomes low level, and the sampling transistor Tr1 is turned off. As a result, the gate G of the driving transistor Trd is disconnected from the signal line SL. Since the application of the video signal V _sig is cancelled, the gate potential (G) of the driving transistor Trd can be increased and increases with the source potential (S). Meanwhile, the gate / source voltage V _gs held in the holding capacitor C _s maintains the value of (V _sig −ΔV + V _th ). As the source potential (S) rises, the reverse bias state of the light emitting element EL is canceled, so that the light emitting element EL actually starts to emit light by the inflow of the output current I _ds . The relationship between the drain current I _{ds and the} gate voltage V _gs at this time is given by the following equation (2) by substituting V _sig −ΔV + V _th into V _gs in the above equation (1).
I _ds = kμ (V _gs −V _th ) ² = kμ (V _sig −ΔV) ² (2)

In the formula (2), k = (1/2) (W / L) C _ox . From the equation (2), it can be seen that the term V _th is canceled and the output current I _ds supplied to the light emitting element EL does not depend on the threshold voltage V _th of the driving transistor Trd. Basically, the drain current I _ds is determined by the signal voltage V _sig of the video signal. In other words, the light emitting element EL emits light with a luminance corresponding to the video signal V _sig . At that time, V _sig is corrected by the feedback amount ΔV. This correction amount ΔV just works to cancel the effect of the mobility μ located in the coefficient part of the equation (2). Therefore, the output current I _ds substantially depends only on the video signal V _sig .

Finally, when the timing T8 is reached, the control signal DS becomes high level, the switching transistor Tr4 is turned off, the light emission ends, and the field ends. Thereafter, the process proceeds to the next field, and the V _th correction operation, the mobility correction operation, and the light emission operation are repeated again.

However, in the pixel of the display device of this reference example, five types of transistors Tr1 to Tr4 and Trd, three types of power supply lines V _ss1 , V _ss2 , V _cc and four types of gate lines (scanning lines) WS, DS, AZ1 AZ2 needs to be formed, and the crossover with the power supply line and the signal line increases. This causes a decrease in the yield of the display device. Furthermore, it becomes difficult to achieve high definition in terms of layout. In a high-definition panel, it is necessary to reduce the number of elements in order to increase the yield.

FIG. 4 shows the overall configuration of an active matrix display device having a threshold voltage (V _th ) correction function according to the first embodiment of the present invention. As shown in FIG. 4, this active matrix type display device is composed of a pixel array section 1 and a peripheral circuit section as main parts. The peripheral circuit unit includes a horizontal selector 3, a write scanner 4, a drive scanner 5, and the like. The pixel array section 1 is composed of scanning lines WS arranged in rows and signal lines SL arranged in columns, and pixels R, G, and B arranged in a matrix at portions where they intersect. In order to enable color display in this display device, RGB three primary color pixels are prepared, but the present invention is not limited to this. Each pixel R, G, B is composed of a pixel 2. The signal line SL is driven by the horizontal selector 3. The horizontal selector 3 forms a signal unit, and generally uses a driver IC, and supplies a video signal to the signal line SL. The scanning line WS is scanned by the write scanner 4. A second scanning line DS is also wired in parallel with the first scanning line WS. The scanning line DS is scanned by the drive scanner 5. The write scanner 4 and the drive scanner 5 constitute a scanner unit, which sequentially scans pixel rows every horizontal scanning period. Each pixel 2 samples a video signal from the signal line SL when selected by the scanning line WS. Further, when selected by the scanning line DS, the light emitting element included in the pixel 2 is driven in accordance with the sampled video signal. In addition, the pixel 2 performs a predetermined correction operation when controlled by the scanning lines WS and DS within the horizontal scanning period.

  The above-described pixel array section 1 is usually formed on an insulating substrate such as a glass substrate (including a normal glass substrate and a quartz glass substrate), and is a flat panel. The transistor included in each pixel 2 is formed of, for example, an amorphous silicon thin film transistor or a low-temperature polycrystalline silicon thin film transistor. In the case of an amorphous silicon thin film transistor, the scanner unit is configured by TAB (tape automated bonding) or the like different from the panel, and is connected to the flat panel by a flexible cable. Similarly, the signal section is also composed of an external driver IC, and is connected to the flat panel with a flexible cable. In the case of a low-temperature polycrystalline silicon thin film transistor, the signal portion and the scanner portion can be formed of the same low-temperature polycrystalline silicon thin film transistor, so that the pixel array portion 1, the signal portion, and the scanner portion can be integrally formed on the flat panel.

FIG. 5 is a circuit diagram showing a configuration of the pixel 2 incorporated in the display device according to the first embodiment of the present invention shown in FIG. The pixel 2 includes a sampling transistor Tr1, a holding capacitor C _s connected thereto, a driving transistor Trd connected thereto, a light emitting element EL connected thereto, and a driving transistor Trd as a power source V _cc And a switching transistor Tr4 connected to the.

The sampling transistor Tr1 is turned on according to the control signal WS supplied from the first scanning line WS, and samples the signal potential V _sig of the video signal supplied from the signal line SL into the holding capacitor C _s . The holding capacitor C _s applies the input voltage V _gs to the gate G of the driving transistor Trd in accordance with the signal potential V _sig of the sampled video signal. The driving transistor Trd supplies an output current I _ds corresponding to the input voltage V _gs to the light emitting element EL. The output current I _ds has a dependency on the threshold voltage V _th of the driving transistor Trd. The light emitting element EL emits light with luminance corresponding to the signal potential V _sig of the video signal by the output current I _ds supplied from the driving transistor Trd during the light emission period. The switching transistor Tr4 is turned on in response to the control signal DS supplied from the second scanning line DS, connects the driving transistor Trd to the power source _Vcc during the light emission period, and is driven in a non-conductive state during the non-light emission period. The transistor Trd is disconnected from the power supply _Vcc .

As a feature of this display device, the scanner unit composed of the write scanner 4 and the drive scanner 5 outputs control signals WS and DS to the first scanning line WS and the second scanning line DS, respectively, in the horizontal scanning period (1H). The preparatory operation for resetting the holding capacitor C _{s in} order to correct the dependency of the output current I _{ds on} the threshold voltage V _th by controlling on / off of the sampling transistor Tr 1 and the switching transistor Tr 4 has been reset. correction operation in the storage capacitor C _s writing voltage for canceling the threshold voltage V _th, and executes a sampling operation for sampling the signal potential of the video signal V _sig to the corrected hold capacitor C _s. On the other hand, the signal section constituted by the horizontal selector 3 _switches the video signal between the first fixed potential V _ssH , the second fixed potential V _ssL, and the signal potential V _sig during the horizontal scanning period (1H). As a result, potentials necessary for the above-described preparation operation, correction operation, and sampling operation are supplied to each pixel 2 via the signal line SL.

Specifically, the horizontal selector 3 first supplies a high-level first fixed potential V _ssH , and then _switches to a low-level second fixed potential V _ssL to enable a preparatory operation. The correction operation is performed in a state where the fixed potential V _ssL is maintained, and then the sampling operation is performed by switching to the signal potential V _sig . The horizontal selector 3 as described above is composed of a driver IC, a signal generating circuit for generating a signal potential V _sig, first fixed potential V _ssH and second fixed potential to the signal potential V _sig output from the signal generating circuit _And an output circuit that inserts V _ssL and synthesizes a video signal in which the first fixed potential V _ssH , the second fixed potential V _ssL, and the signal potential V _sig are _switched, and outputs the synthesized video signal to each signal line SL. Preferably, the driver IC constituting the horizontal selector 3 outputs a video signal obtained by synthesizing the signal potential V _sig not exceeding the normal rating and the first fixed potential V _ssH exceeding the rating. In this case, the signal generation circuit included in the driver IC has a normal breakdown voltage to generate the signal potential V _sig that does not exceed the rating, while the output circuit has a high breakdown voltage to cope with the first fixed potential V _ssH that exceeds the rating. It has become.

In the driving transistor Trd, the output current I _ds has dependency on the carrier mobility μ in the channel region in addition to the threshold voltage V _th . In this case, the scanner unit constituted by the write scanner 4 and the drive scanner 5 outputs a control signal to the second scanning line DS in the horizontal scanning period (1H), further controls the switching transistor Tr4, and outputs an output current I _ds. In order to cancel the dependence on the carrier mobility μ, the output current I _ds is taken out from the driving transistor Trd while the signal potential V _sig is sampled, and this is negatively fed back to the holding capacitor C _s to input voltage V Execute the operation to correct _gs .

FIG. 6 is a schematic view of the pixel 2 portion extracted from the display device shown in FIG. In order to facilitate understanding, the video signal V _sig sampled by the sampling transistor Tr1, the input voltage V _gs and output current I _{ds of} the driving transistor Trd, and the capacitance component C _oled of the light emitting element EL are added. It is. The scanning lines WS and DS connected to the gates of the transistors are also written. The pixel 2 performs a V _th correction preparation operation, an actual correction operation, and a signal potential sampling operation within the horizontal scanning period (1H). Thus, the pixel 2 can be configured by the three transistors Tr1, Tr4, Trd and one of the storage capacitor C _s and one light emitting element EL. Compared to the pixel circuit incorporating the _Vth correction function in the display device of the reference example shown in FIG. 1, at least two transistors can be reduced. Thereby, power supply lines and gate lines can be reduced, and the yield of the panel can be improved. Further, the layout of the pixel 2 can be simplified, and high definition can be achieved.

FIG. 7 is a timing chart of the pixels shown in FIGS. 5 and 6. With reference to FIG. 7, the operation of the pixel 2 shown in FIG. 5 and FIG. 6 will be described specifically and in detail. FIG. 7 shows the waveforms of control signals applied to the scanning lines WS and DS along the time axis T. In order to simplify the notation, the control signals are also denoted by the same reference numerals as the corresponding scanning lines. In addition, the waveform of the video signal applied to the signal line is also shown along the time axis T. As shown in FIG. 7, this video signal is switched in sequence to a high potential V _ssH , a low potential V _ssL , and a signal potential V _sig within each horizontal scanning period (1H). Since the transistor Tr1 is an n-channel type, it is turned on when the scanning line WS is at a high level and turned off when it is at a low level. On the other hand, since the transistor Tr4 is a p-channel type, it is turned off when the scanning line DS is at a high level and turned on when it is at a low level. This timing chart also shows the change in the potential of the gate G and the change in the potential of the source S of the drive transistor Trd, along with the waveforms of the control signals WS and DS and the waveform of the video signal.

  In the timing chart of FIG. 7, timings T1 to T8 are defined as one field (1f). Each row of the pixel array unit 1 is sequentially scanned once during one field. The timing chart shows the waveforms of the control signals WS and DS applied to one row of pixels.

First, at timing T1, the switching transistor Tr4 is turned off to emit no light. At this time, the source potential of the driving transistor Trd is because there is no power supply from V _cc, is lowered to the cut-off voltage V _thEL of the light-emitting device EL.

Next, at timing T2, the sampling transistor Tr1 is turned on. However, it is _preferable to increase the signal line voltage to V _ssH before this time because the writing time can be shortened. By turning on the sampling transistor Tr1, V _ssH is written as the gate potential of the driving transistor Trd. At this time, coupling enters the source potential via the storage capacitor C _s and the source potential rises. Although the potential of the source S rises once, it is discharged through the light emitting element EL, so that the source voltage becomes V _thEL again. At this time, the gate voltage remains V _ssH .

Next, at the timing Ta, the signal voltage is changed to V _ssL while the sampling transistor Tr1 is turned on. This potential change is coupled to a source potential via a storage capacitor C _s. The amount of coupling at this time is determined by C _s / (C _s + C _oled ) × (V _ssH −V _ssL ). At this time, the gate potential is _expressed as V _ssL , and the source potential is expressed as V _thEL −C _s / (C _s + C _oled ) × (V _ssH −V _ssL ). Since a negative bias is applied here, the source voltage becomes _lower than V _thEL and the light emitting element EL is cut off. Here, the source potential is desirably set to a potential at which the light emitting element EL continues to be cut off after the subsequent _Vth correction and mobility correction. Further, by preparing coupling so that V _gd > V _th , preparation for V _th correction can be made. As described above, V _th correction preparation can be performed even in a circuit in which transistors, power supply lines, and gate lines are reduced. That is, the timings T2 to Ta are included in the correction preparation period.

Thereafter, when the switching transistor Tr4 is turned on with the gate G held at V _ssL at the timing T3, a current flows through the driving transistor Trd, and _Vth correction is performed as in the display device of the reference example. A current flows until the driving transistor Trd is cut off. When the driving transistor Trd is cut off, the source potential of the driving transistor Trd becomes V _ssL −V _th . Here, it is necessary to _satisfy V _ssL −V _th <V _thEL .

Thereafter, at timing T4, the switching transistor Tr4 is turned off, and the _Vth correction ends. That is, the timings T3 to T4 are the _Vth correction period.
After performing _Vth correction at timings T3 to T4 in this way, the potential of the signal line changes from V _ssL to V _sig at timing T5. Thereby, the signal potential V _sig of the video signal is written in the storage capacitor C _s . The holding capacity C _s is sufficiently smaller than the equivalent capacity C _oled of the light emitting element EL. As a result, most of the signal potential V _sig is written into the storage capacitor C _s . Therefore, the voltage V _gs between the gate G and the source S of the driving transistor Trd becomes a level (V _sig + V _th ) obtained by adding V _th previously detected and held and V _sig sampled this time. That is, the input voltage V _gs for the driving transistor Trd is V _sig + V _th . The signal voltage V _sig is sampled until timing T7 when the control signal WS returns to the low level. That is, timings T5 to T7 correspond to the sampling period.

The pixel 2 of this display device also corrects the mobility μ in addition to the correction of the threshold voltage V _th described above. The mobility μ is corrected at timings T6 to T7. This point will be described in detail later. In conclusion, as shown in the timing chart, the correction amount ΔV is subtracted from the input voltage V _gs .

At timing T7, the control signal WS becomes low level, and the sampling transistor Tr1 is turned off. As a result, the gate G of the driving transistor Trd is disconnected from the signal line SL. Since the application of the video signal V _sig is cancelled, the gate potential (G) of the driving transistor Trd can be increased and increases with the source potential (S). Meanwhile, the gate / source voltage V _gs held in the holding capacitor C _s maintains the value of (V _sig −ΔV + V _th ). As the source potential (S) rises, the reverse bias state of the light emitting element EL is canceled, so that the light emitting element EL actually starts to emit light by the inflow of the output current I _ds . The relationship between the drain current I _{ds and the} gate voltage V _gs at this time is given by the equation (2). From this equation (2), it can be seen that the term V _th is canceled and the output current I _ds supplied to the light emitting element EL does not depend on the threshold voltage V _th of the driving transistor Trd. Basically, the drain current I _ds is determined by the signal voltage V _sig of the video signal. In other words, the light emitting element EL emits light with a luminance corresponding to the video signal V _sig . At that time, V _sig is corrected by the feedback amount ΔV. This correction amount ΔV just works to cancel the effect of the mobility μ located in the coefficient part of the equation (2). Therefore, the output current I _ds substantially depends only on the video signal V _sig .

Finally, when the timing T8 is reached, the control signal DS becomes high level, the switching transistor Tr4 is turned off, the light emission ends, and the field ends. Thereafter, the process proceeds to the next field, and the correction preparation operation, the V _th correction operation, the mobility correction operation, and the light emission operation are repeated again.

FIG. 8 is a circuit diagram showing a state of the pixel 2 in the mobility correction period T6-T7. As shown in FIG. 8, in the mobility correction period T6-T7, the sampling transistor Tr1 and the switching transistor Tr4 are turned on, while the remaining switching transistors Tr3 are turned off. In this state, the source potential (S) of the driving transistor Tr4 is V _ssL −V _th . This source potential S is also the anode potential of the light emitting element EL. By setting V _ssL −V _th <V _thEL as described above, the light emitting element EL is placed in a reverse bias state and exhibits simple capacitance characteristics instead of diode characteristics. Accordingly, the current I _ds flowing through the driving transistor Trd flows into the combined capacitance C = C _s + C _oled of the holding capacitor C _s and the equivalent capacitance C _oled of the light emitting element EL. In other words, a part of the drain current I _ds is negatively fed back to the storage capacitor C _s and the mobility is corrected.

FIG. 9 is a graph of the above equation (2), where I _ds is on the vertical axis and V _sig is on the horizontal axis. The formula (2) is also shown below the graph. In the graph of FIG. 9, a characteristic curve is drawn in a state where the pixel 1 and the pixel 2 are compared. The mobility μ of the driving transistor included in the pixel 1 is relatively large. On the contrary, the mobility μ of the driving transistor included in the pixel 2 is relatively small. Thus, when the driving transistor is formed of a polycrystalline silicon thin film transistor or the like, it is inevitable that the mobility μ varies between pixels. For example, when the video signal V _sig of the same level is written in the pixels 1 and 2, the output current I _ds1 ′ flowing in the pixel 1 having the high mobility μ is small in the mobility μ without any mobility correction. A large difference is generated as compared with the output current I _ds2 ′ flowing through the pixel 2. As described above, a large difference is generated between the output currents I _ds due to the variation in the mobility μ, so that the uniformity of the screen is impaired.

Therefore, in this display device, the variation in mobility μ is canceled by negatively feeding back the output current I _ds to the input voltage side. As apparent from the equation (2), the output current I _ds increases when the mobility μ is large. Therefore, the negative feedback amount ΔV increases as the mobility μ increases. As shown in the graph of FIG. 9, the negative feedback amount ΔV1 of the pixel 1 having a high mobility μ is larger than the negative feedback amount ΔV2 of the pixel 2 having a low mobility μ. Therefore, the larger the mobility μ is, the more negative feedback is applied, so that the variation in mobility μ can be suppressed. As shown in FIG. 9, when applying a correction of the mobility in large pixel 1 mu [Delta] V1, the output current is large drops from I _ds1 'to I _ds1. On the other hand, since the correction amount ΔV2 of the pixel 2 having the low mobility μ is small, the output current I _ds2 ′ does not decrease so much to I _ds2 . Consequently, I _ds1 and I _ds2 is approximately equal, the variation in the mobility μ is canceled. Since the cancellation of the variation in mobility μ is performed in the entire range of V _sig from the black level to the white level, the uniformity of the screen becomes extremely high. In summary, when there are a pixel 1 and a pixel 2 having different mobility μ, the correction amount ΔV1 of the pixel 1 having a high mobility μ is smaller than the correction amount ΔV2 of the pixel 2 having a low mobility μ. That is, as the mobility μ increases, ΔV increases and the decrease value of I _ds increases. As a result, the current values of the pixels having different mobility μ are made uniform, and variations in mobility μ can be corrected.

Hereinafter, for reference, numerical analysis of the mobility correction described above is performed with reference to FIG. As shown in FIG. 10, the analysis is performed by taking the source potential of the driving transistor Trd as a variable V while the transistors Tr1 and Tr4 are turned on. Assuming that the source potential (S) of the driving transistor Trd is V, the drain current I _ds flowing through the driving transistor Trd is as shown in the following equation (3).

In addition, I _ds = dQ / dt = CdV / dt is established as shown in the following equation (4) based on the relationship between the drain current I _ds and the capacitance C (= C _s + C _oled ).

Integrate both sides by substituting equation (3) into equation (4). Here, the initial state of the source voltage V is -V _th, the mobility variation correction time (T6-T7) and t. When this differential equation is solved, the pixel current with respect to the mobility correction time t is given by the following equation (5).

FIG. 11 is a graph of the expression (5), in which the vertical axis represents the output current I _ds and the horizontal axis represents the video signal V _sig . In FIG. 11, mobility correction periods t = 0 μs, 2.5 μs, and 5 μs are set as parameters. Further, when the mobility μ is a relatively large parameter, the parameter is 1.2 μ and the relatively small value is 0.8 μ. It can be seen that the mobility variation is sufficiently corrected at t = 2.5 μs as compared to the case where the mobility correction is not substantially applied at t = 0 μs. Without mobility correction, _Ids with 40% variation can be suppressed to 10% or less when mobility correction is applied. However, if t = 5 μs and the correction period is lengthened, the output current I _ds varies greatly due to the difference in mobility μ. Thus, in order to perform appropriate mobility correction, it is necessary to set t to an optimal value. In the case of the graph shown in FIG. 11, the optimum value is in the vicinity of t = 2.5 μs.

In the display device having the circuit configuration as described above, in particular among the elements included in the pixel 2, the structure of a portion of the driving transistor Trd and the storage capacitor C _s consisting TFT shown in FIG. 12. As shown in FIG. 12, the gate wiring 52 of the driving transistor Trd and one electrode 53 of the storage capacitor C _s are provided on the glass substrate 51 by the first-layer wiring material. A gate insulating film 54 is provided so as to cover the end portions of the gate wiring 52 and the electrode 53. A polycrystalline silicon film 55 having a predetermined shape is provided on the gate insulating film 54 in the portion above the driving transistor portion. Although not shown, a source region and a drain region are formed in the polycrystalline silicon film 55 in a self-aligned manner with respect to the gate wiring 52. The gate electrode formed of the gate wiring 52 and these source region and drain region constitute a bottom gate type polycrystalline silicon thin film transistor as the driving transistor Trd. An interlayer insulating film 56 is provided so as to cover the polycrystalline silicon film 55 and the gate insulating film 54. A contact hole 57 is provided in the interlayer insulating film 56 in the portion above the electrode 53. Further, a dielectric film 58 is provided on the interlayer insulating film 56 and on the electrode 53 in the contact hole 57 portion. An electrode 59 is provided on the dielectric film 58 in the upper portion of the storage capacitor portion by using a second-layer wiring material. The storage capacitor C _s is configured by a structure in which the dielectric film 58 is sandwiched between the electrode 59 and the electrode 53. In the interlayer insulating film 56 and the dielectric film 58, contact holes 60 and 61 are provided in portions above the source region and the drain region formed in the polycrystalline silicon film 55. Then, wirings 62 and 63 are formed of the second-layer wiring material through these contact holes 60 and 61.
Although illustration and description are omitted, actually, for example, an interlayer insulating film is provided on the wirings 62 and 63 and the electrode 59 described above, and an anode electrode, a hole injection layer, a hole transport layer, a light emitting layer, A light emitting element 3D composed of an organic EL element is formed by sequentially stacking an electron transport layer, a cathode electrode, and the like, and further a passivation film is formed thereon, and a sealing substrate is formed thereon via an adhesive. These can be conventionally known ones.

As described above, in this display device, the gate insulating film 54 of the driving transistor Trd of the pixel 2 and the dielectric film 58 constituting the storage capacitor C _s are formed independently of each other. Therefore, the material and thickness of the gate insulating film 54 can be optimized according to the transistor characteristics required for the driving transistor Trd, and the material and thickness of the dielectric film 58 constituting the storage capacitor C _s can also be optimized. Independent of the gate insulating film 54, the storage capacity C _s can be optimized so that a sufficient storage capacity can be ensured according to the area that can be used. That is, when the pitch of the pixels 2 is reduced and an area that can be used for forming the storage capacitor C _s cannot be secured sufficiently, the dielectric film 58 is made more dielectric than the gate insulating film 54. A sufficient storage capacity can be ensured by using a material having a high rate or by making the thickness of the dielectric film 58 smaller than that of the gate insulating film 54. Specifically, for example, a silicon oxide film / silicon nitride film, which is a two-layer film, is used as the gate insulating film 54, while a silicon nitride film having a dielectric constant larger than that of the silicon oxide film, strontium titanate (STO), as the dielectric film 58. By using a film, a lead zirconate titanate (PZT) film, a tantalum pentoxide (Ta ₂ O ₅ ) film, etc., a sufficiently large storage capacity C _s can be secured even in a small area.

As described above, according to this display device, even when the pitch of the pixels 2 is reduced as the screen becomes higher definition, the transistor characteristics of the driving transistor Trd formed of the thin film transistors included in the pixels 2 are sufficiently changed. A large storage capacity C _s can be secured, and a high-quality video can be displayed. In this display device, the V _th correction preparation by changing the gate voltage from the high voltage to the low voltage and the V _th correction operation are performed within one horizontal scanning period, and then the video signal is transmitted within the same horizontal scanning period. To write. With this operation, the power lines, switching transistors, gate lines, and the like can be reduced by sharing the three types of power sources, which have been required in the past, with the signal lines, and a pixel circuit having three transistors and one capacity can be configured. Can do. As described above, the yield of the panel can be improved. Further, since the area of the pixel can be reduced by reducing elements included in the pixel, high definition can be achieved. In this display device, the mobility correction is performed by turning on the switching transistor Tr4 while the sampling transistor Tr1 is turned on. However, the mobility correction is performed by making the sampling transistor Tr1 and the switching transistor Tr4 non-overlapping. Even in a simple V _th correction operation without _{performing the above} , the number of wirings and transistors can be similarly reduced. In this display device, n-channel transistors are used as switching transistors other than the driving transistor Trd. However, the characteristics of each transistor may be n-channel or p-channel.

Next explained is an active matrix display device according to the second embodiment of the invention.
The second embodiment is particularly characterized by a data driver that constitutes a signal unit (horizontal selector) of the display device. That is, in the second embodiment, a signal driver arranged in the column direction of the display device and used for displaying image data switches between a signal potential representing image data and a fixed potential for pixel control and outputs the result. When the fixed potential for pixel control requires a voltage amplitude higher than the maximum rated voltage of a general data driver, the signal potential for image data near the output terminal and the fixed potential for pixel control By increasing the breakdown voltage of only the switch function part that switches the potential, the necessary functions can be realized in the driver manufacturing process without changing to a higher breakdown voltage process, changing the circuit size, or increasing the pin pitch. It is possible to do.

13A and 13B show an example of a pixel (FIG. 13A) and a drive waveform (FIG. 13B) of a display device in which a signal potential representing image data and a fixed potential for pixel control are mixed on a data signal line. The pixel 2 shown in FIG. 13A includes three transistors, one storage capacitor C _s , and one light emitting element EL. The pixel 2 of the display device according to the first embodiment shown in FIG. Is generalized. The video signal V _sig is supplied from the data signal line SL. The driving transistor Trd is driven by the voltage value of the signal V _sig to cause the light emitting element EL to emit light with a desired brightness. In this display device, since the characteristic variation of the driving transistor Trd directly affects the image quality at this time, the storage capacitor C _s is used to correct this variation during the correction period. When performing this correction operation, a fixed potential V _st for control is sent to the pixel 2 from the data signal line SL using the drive waveforms of the scan pulse WA and the scan pulse DS. In a normal display device, a signal line for an image data system and a signal line for a drive control system are separated from each other. When inputting a control system signal, another wiring is arranged and another scanning pulse is used. . However, if the number of elements in the pixel 2 increases, the yield deteriorates due to transistor defects, and the area required for one pixel 2 increases. Therefore, adverse effects such as a decrease in physical resolution can be considered. In order to reduce the number of elements of 2 as much as possible and correct the characteristic variation of the driving transistor Trd, the signal potential V _pc corresponding to the image data and the fixed potential V _st for controlling the pixel 2 are sampled from the data signal line SL. It is necessary to transmit separately at the time of correction and correction.

At this time, the fixed voltage V _st for controlling the pixel 2 is not necessarily in the same range as the signal voltage V _{pc of the} image data. As in the example of the waveform timing chart shown in FIG. 13B, the control signal voltage V _st may be higher than the image signal voltage V _pc , and V _st may be higher than the rated voltage of the data driver IC. . Normally, the driver output is indefinite (high impedance) during the non-display period, but in the case of this pixel 2, V _st and V _pc are separated into a sampling period and a correction period, and the voltage between them is ground. It may be necessary to fix to the level GND.

  FIG. 14 shows a block configuration of the data driver IC 3 that satisfies such a drive waveform condition. A portion surrounded by a square solid line is a high-breakdown-voltage output circuit section 32. If only a circuit in this is increased in the breakdown voltage by increasing the wiring film thickness, the image signal generation circuit section 31 has a normal configuration. It can be manufactured by withstand voltage and process. The output circuit section 32 includes voltage switching switches SW1 and SW2. However, since the control signal for the switch SW1 and the control signal for the switch SW2 are logic signals for controlling ON / OFF of the switch, there is no need to increase the breakdown voltage.

The output terminal 31B of the image signal generation circuit unit 31 outputs output voltages V _{pc1 to} V _pcn having the image display system power supply voltage V _pc as a maximum voltage. This output voltage is sent to the switch SW1 and switched to a fixed voltage for pixel circuit control. The fixed voltage for controlling the pixel circuit is a logic pulse having an amplitude of the control system power supply voltage _Vst . The output of the switch SW1 is sent to the switch SW2. In the switch SW2, to secure the output terminal to the GND level at the time of switching between V _pc1 ~V _pcn and V _st, performs signal or GND Kano selection. As a result, as the final output signal V _sig is the final output end 32B, control system power supply voltage maximum value V _pc1 ~V _pcn or GND level voltage with a maximum value of V _st or image display system power supply voltage to the output Is done.
In this display device, the structure of the drive transistor Trd made of a thin film transistor and the storage capacitor C _s among the elements included in the pixel 2 is the same as that shown in FIG.

Next explained is an active matrix display device according to the third embodiment of the invention.
First, in order to facilitate understanding of the active matrix display device and clarify the background, an outline of the active matrix display device from which the active matrix display device is based will be described with reference to FIG. explain.
FIG. 15 is a schematic circuit diagram showing one pixel of this display device. As shown in FIG. 15, in this pixel, sampling transistors 1A are arranged at intersections between scanning lines 1E arranged in rows and signal lines 1F arranged in columns. The sampling transistor 1A is an n-channel type, and has a gate connected to the scanning line 1E and a drain connected to the signal line 1F. One electrode of the storage capacitor 1C and the gate of the driving transistor 1B are connected to the source of the sampling transistor 1A. The driving transistor 1B is an n-channel type, and its drain is connected to the power supply line 1G, and its source is connected to the anode of the light emitting element 1D. The other electrode of the storage capacitor 1C and the cathode of the light emitting element 1D are connected to the ground wiring 1H.

FIG. 16 is a timing chart showing the operation of the pixel shown in FIG. This timing chart represents an operation of sampling the potential of the video signal supplied from the signal line 1F (video signal line potential) and setting the light emitting element 1D made of an organic EL element or the like to a light emitting state. When the potential of the scanning line 1E (scanning line potential) transitions to a high level, the sampling transistor 1A is turned on and charges the holding capacitor 1C with the video signal line potential. As a result, the gate potential (V _g ) of the driving transistor 1B starts to rise and starts to flow a drain current. For this reason, the anode potential of the light emitting element 1D rises and light emission starts. Thereafter, when the scanning line potential transitions to a low level, the video signal line potential is held in the holding capacitor 1C, the gate potential of the driving transistor 1B becomes constant, and the light emission luminance is kept constant until the next frame.

  However, due to variations in the manufacturing process of the driving transistor 1B, characteristics such as threshold voltage and mobility vary for each pixel. Due to this characteristic variation, even if the same gate potential is applied to the driving transistor 1B, the drain current (driving current) varies from pixel to pixel, resulting in variations in light emission luminance. Further, the anode potential of the light emitting element 1D varies due to the temporal variation of the characteristics of the light emitting element 1D made of an organic EL element or the like. This variation in the anode potential appears as a variation in the gate-source voltage of the driving transistor 1B, causing a variation in the drain current (driving current). Such fluctuations in the drive current due to various causes appear as variations in light emission luminance from pixel to pixel, resulting in degradation of image quality.

  FIG. 17 is a block diagram showing the overall configuration of the display device according to the third embodiment. As shown in FIG. 17, the display device 100 includes a pixel array unit 102 and a drive unit that drives the pixel array unit 102. The pixel array unit 102 includes scanning lines WSL101 to 10m arranged in rows, signal lines DTL101 to 10n arranged in columns, matrix-like pixels (PXLC) 101 arranged in portions where both intersect, Power supply lines DSL101 to 10m arranged corresponding to each row of each pixel 101 are provided. The driving unit sequentially supplies control signals to the scanning lines WSL101 to 10m to scan the pixels 101 line-sequentially in units of rows, and the power supply lines DSL101 to DSL101 to the line-sequential scanning. A power supply scanner (DSCN) 105 that supplies a power supply voltage that switches between the first potential and the second potential at 10 m, and a signal potential that becomes a video signal on the column-like signal lines DTL101 to 10n in accordance with the line sequential scanning. And a signal selector (horizontal selector HSEL) 103 for supplying the reference potential.

FIG. 18 is a circuit diagram showing a specific configuration and connection relationship of the pixel 101 included in the display device 100 shown in FIG. As shown in FIG. 18, the pixel 101 includes a light emitting element 3D such as an organic EL element, a sampling transistor 3A, a driving transistor 3B, and a storage capacitor 3C. Sampling transistor 3A has its gate connected to corresponding scanning line WSL101, one of its source and drain connected to corresponding signal line DTL101, and the other connected to gate g of driving transistor 3B. One of the source s and drain d of the driving transistor 3B is connected to the light emitting element 3D, and the other is connected to the corresponding power supply line DSL101. The drain d of the driving transistor 3B is connected to the power supply line DSL101, while the source s is connected to the anode of the light emitting element 3D. The cathode of the light emitting element 3D is connected to the ground wiring 3H. The ground wiring 3H is wired in common to all the pixels 101. The storage capacitor 3C is connected between the source s and the gate g of the driving transistor 3B.
In this display device, the structures of the driving transistor 3B and the storage capacitor 3C made of thin film transistors among the elements included in the pixel 101 are the same as those shown in FIG.

In the display device configured as described above, the sampling transistor 3A is turned on in accordance with the control signal supplied from the scanning line WSL101, samples the signal potential supplied from the signal line DTL101, and holds it in the holding capacitor 3C. To do. The driving transistor 3B receives supply of current from the power supply line DSL101 at the first potential, and flows drive current to the light emitting element 3D according to the signal potential held in the holding capacitor 3C. The power supply scanner (DSCN) 105 sets the power supply line DSL101 to the first potential and the second potential while the signal selector (HSEL) 103 supplies the reference potential to the signal line DTL101 after the sampling transistor 3A is turned on. Thus, a voltage corresponding to the threshold voltage V _th of the driving transistor 3B is held in the holding capacitor 3C. With this threshold voltage correction function, the display device 100 can cancel the influence of the threshold voltage of the driving transistor 3B, which varies from pixel to pixel.

  A pixel 101 shown in FIG. 18 has a mobility correction function in addition to the threshold voltage correction function described above. That is, the signal selector (HSEL) 103 switches the signal line DTL101 from the reference potential to the signal potential at the first timing after the sampling transistor 3A is turned on, while the main scanner (WSCN) 104 is switched after the first timing. Holding by applying the control signal to the scanning line WSL101 at the second timing to place the sampling transistor 3A in the non-passing state and appropriately setting the period between the first timing and the second timing. When the signal potential is held in the capacitor 3C, correction for the mobility μ of the driving transistor 3B is added to the signal potential. In this case, the drive unit adjusts the relative phase difference between the video signal supplied from the signal selector 103 and the control signal supplied from the main scanner 104, and a period between the first timing and the second timing. (Mobility correction period) can be optimized. The signal selector 103 also automatically follows the signal potential during the mobility correction period between the first timing and the second timing by inclining the rising edge of the video signal that switches from the reference potential to the signal potential. It can also be made.

The pixel 101 shown in FIG. 18 further has a bootstrap function. That is, the main scanner (WSCN) 104 cancels the application of the control signal to the scanning line WSL101 at the stage where the signal potential is held in the holding capacitor 3C, makes the sampling transistor 3A non-conductive, and the gate of the driving transistor 3B. g is electrically disconnected from the signal line DTL101, whereby the gate potential (V _g ) is interlocked with the fluctuation of the source potential (V _s ) of the driving transistor 3B, and the voltage V _gs between the gate g and the source s is changed. Can be kept constant.

FIG. 19 is a timing chart showing the operation of the pixel 101 shown in FIG. In FIG. 19, the change in the potential of the scanning line (WSL 101), the change in the potential of the power supply line (DSL 101), and the change in the potential of the signal line (DTL 101) are shown with a common time axis. In addition to these potential changes, changes in the gate potential (V _g ) and source potential (V _s ) of the driving transistor 3B are also shown.

In this timing chart, the period is divided for convenience as shown in (B) to (G) in accordance with the transition of the operation of the pixel 101. In the light emission period (B), the light emitting element 3D is in a light emitting state. Thereafter, in the first period (C) after entering a new field of line sequential scanning, the gate potential V _g of the driving transistor 3B is initialized. In the next period (D), the source potential V _s of the driving transistor is also initialized. Thus, by preparing the gate potential V _g and the source potential V _s of the driving transistor 3B, the preparation for the threshold voltage correction operation is completed. Subsequently, a threshold voltage correction operation is actually performed in the threshold voltage correction period (E), and a voltage corresponding to the threshold voltage _Vth is held between the gate g and the source s of the driving transistor 3B. The Actually, a voltage corresponding to V _th is written in the holding capacitor 3C connected between the gate g and the source s of the driving transistor 3B. Then, the procedure proceeds to the sampling period / mobility correction period (F), with the signal potential V _in the video signal is written into the holding capacitor 3C in the form to be added together to V _th, the voltage ΔV for mobility correction holding capacitor Subtracted from the voltage held at 3C. Then, the process proceeds to the light emitting period (G), the light-emitting device 3D with a luminance corresponding to the signal voltage V _in to light emission. In this case, since the signal voltage V _in is adjusted by a voltage ΔV for mobility correction voltage corresponding to the threshold voltage V _th, the emission luminance of the light-emitting device 3D is the threshold voltage of the drive transistor 3B It is not affected by variations in V _th and mobility μ. Note that a bootstrap operation is performed at the beginning of the light emission period (G), and the gate potential of the driving transistor 3B is maintained while maintaining the gate-source voltage V _gs = V _in + V _th −ΔV of the driving transistor 3B constant. V _g and source potential V _s rise.

Next, the operation of the pixel 101 shown in FIG. 18 will be described in detail with reference to FIGS. 20 to 25 correspond to the periods (B) to (G) of the timing chart shown in FIG. 19, respectively. In order to facilitate understanding, in FIGS. 20 to 25, the capacitive component of the light emitting element 3D is shown as the capacitive element 3I. First, as shown in FIG. 20, the light emitting period (B), the power supply line DSL101 is at a high potential V _cc _H (first potential), the drive transistor 3B supplies a drive current I _ds to the light emitting element 3D Yes.
As shown in FIG. 20, the drive current I _ds flows from the power supply line DSL101 at the high potential V _cc —H through the light emitting element 3D through the drive transistor 3B and flows into the common ground wiring 3H.

Once in the period (C) Subsequently, as shown in FIG. 21, the sampling transistor 3A by scanning line WSL101 is shifted to the high potential side is turned on, the gate potential V _g of the drive transistor 3B video signal lines Initialized (reset) to the reference potential V _{0 of the} DTL 101.

Now proceeds to the period (D), as shown in FIG. 22, the potential of the power supply line DSL101 is high potential V _cc _H (first potential) sufficiently lower than the reference potential V ₀ video signal line DTL101 from the potential V _cc Transition to _L (second potential). As a result, the source potential V _s of the driving transistor 3B is initialized (reset) to a potential V _cc _L that is sufficiently lower than the reference potential V ₀ of the video signal line DTL101. Specifically, the power source is set so that the gate-source voltage V _gs (the difference between the gate potential V _g and the source potential V _s ) of the driving transistor 3B is larger than the threshold voltage V _th of the driving transistor 3B. The low potential V _cc _L (second potential) of the supply line DSL101 is set.

Now proceeds to the threshold voltage correction period (E), as shown in FIG. 23, the potential of the power supply line DSL101 changes from the low potential V _cc _L to the high potential V _cc _H, the source potential of the driving transistor 3B V _s begins to rise. Eventually, the current is cut off when the gate-source voltage V _{gs of the} driving transistor 3B reaches the threshold voltage V _th . In this way, a voltage corresponding to the threshold voltage V _th of the driving transistor 3B is written to the storage capacitor 3C. This is the threshold voltage correction operation. At this time, the potential of the common ground wiring 3H is set so that the light emitting element 3D is cut off in order to prevent the current from flowing exclusively to the storage capacitor 3C and not to the light emitting element 3D.

Now proceeds to the sampling period / mobility correction period (F), as shown in FIG. 24, a transition from a reference potential V ₀ which is the potential of the video signal line DTL101 to the signal potential V _in at the first timing, drive The gate potential V _g of the transistor 3B is V _in . At this time, since the light emitting element 3D is initially in a cutoff state (high impedance state), the drain current I _ds of the driving transistor 3B flows into the parasitic capacitance 3I of the light emitting element. Thereby, the parasitic capacitance 3I of the light emitting element starts to be charged. As a result, the source potential V _s of the driving transistor 3B starts to rise, and the gate-source voltage V _gs of the driving transistor 3B becomes V _in + V _th −ΔV at the second timing. In this manner, the adjustment of sampling the correction amount ΔV of the signal potential V _in is performed. As V _in is higher, I _ds increases and the absolute value of ΔV also increases. Therefore, mobility correction according to the light emission luminance level can be performed. Further, when the V _in is constant, the greater the absolute value of the mobility as μ is large ΔV of the drive transistor 3B. In other words, since the negative feedback amount ΔV increases as the mobility μ increases, it is possible to eliminate variations in the mobility μ for each pixel.

Finally, in the light emission period (G), as shown in FIG. 25, the scanning line WSL101 transitions to the low potential side, and the sampling transistor 3A is turned off. As a result, the gate g of the driving transistor 3B is disconnected from the signal line DTL101. At the same time, the drain current I _ds starts to flow through the light emitting element 3D. As a result, the anode potential of the light emitting element 3D rises according to the drive current _Ids . Rise in the anode potential of the light-emitting device 3D is nothing but an increase in the source potential V _s of the drive transistor 3B. When the source potential V _s of the driving transistor 3B rises, the gate potential V _g of the driving transistor 3B also rises in conjunction with the bootstrap operation of the storage capacitor 3C. Increase the amount of the gate potential V _g is equal to the rise amount of the source potential V _s. Therefore, the gate-source voltage V _gs of the driving transistor 3B is kept constant at V _in + V _th −ΔV during the light emission period.

FIG. 26 is a graph showing the current-voltage characteristics of the driving transistor. In particular, the drain-source current I _ds when the driving transistor is operating in the saturation region is expressed by equation (1). As apparent from the equation (1), when the threshold voltage V _th varies, the drain-source current I _ds varies even if V _gs is constant. Here, in the pixel of this display device, as described above, since the gate-source voltage V _gs at the time of light emission is expressed by V _in + V _th −ΔV, if this is substituted into the equation (1), the drain− The inter-source current I _ds is expressed by I _ds = (1/2) μ (W / L) Cox (V _in −ΔV) ² and does not depend on the threshold voltage V _th . As a result, even if the threshold voltage V _th varies depending on the manufacturing process, the drain-source current I _ds does not vary, and the light emission luminance of the light emitting element 3D such as an organic EL element does not vary.

On the other hand, if no measures are taken, the drive current corresponding to V _gs becomes I _ds when the threshold voltage is V _th as shown in FIG. 26, whereas the same gate is obtained when the threshold voltage is V _th ′. The drive current I _ds ′ corresponding to the voltage V _gs is different from I _ds .

FIG. 27 is a graph showing the current-voltage characteristics of the driving transistors, and the characteristic curves are shown for two driving transistors having different mobility in μ and μ ′. As apparent from FIG. 27, when the mobility is different between μ and μ ′, the drain-source current becomes I _ds and I _ds ′ and fluctuates even if V _gs is constant.

FIG. 28 illustrates the operation of the pixel at the time of sampling the video signal potential and correcting the mobility, and also shows the parasitic capacitance 3I of the light emitting element 3D for easy understanding. The sampling of the video signal potential, the gate potential V _g of the drive transistor 3B for sampling transistor 3A is turned on the video signal potential V _in, and the gate of the drive transistor 3B - source voltage V _gs is V _in + V Become _th . The drive transistor 3B at this time is turned on, further since the light-emitting device 3D is cut off, the drain - source current I _ds flows to the light-emitting device capacitance 3I. When the drain-source current I _ds flows into the light emitting element capacitor 3I, the light emitting element capacitor 3I starts to be charged, and the anode of the light emitting element 3D (therefore, the source potential V _s of the driving transistor 3B) starts to rise. When the source potential V _s of the driving transistor 3B increases by ΔV, the gate-source voltage V _gs of the driving transistor 3B decreases by ΔV. This is a mobility correction operation by negative feedback, and the reduction amount ΔV of the gate-source voltage V _gs is determined by ΔV = I _ds · C _el / t, and ΔV is a parameter for mobility correction. Here C _el indicates the capacitance value of the light-emitting device capacitance 3I, t represents the mobility correction period (the period between the first timing and the second timing).

FIG. 29 is a schematic diagram illustrating the operation timing of the pixel circuit that determines the mobility correction period t. In the example shown in FIG. 29, the rising of the video line signal potential is inclined to automatically follow the mobility correction period t to the video line signal potential, thereby optimizing it. As shown in FIG. 29, the mobility correction period t is determined by the phase difference between the scanning line WS101 and the video signal line DTL101, and is further determined by the potential of the video signal line DTL101. The mobility correction parameter ΔV is ΔV = I _ds · C _el / t. As is apparent from this equation, the mobility correction parameter ΔV increases as the drain-source current I _ds of the driving transistor 3B increases. Conversely, when the drain-source current Ids of the driving transistor 3B is small, the mobility correction parameter ΔV is small. Thus, the mobility correction parameter ΔV is determined according to the drain-source current I _ds . At that time, the mobility correction period t is not necessarily constant, and conversely, it may be preferable to adjust the mobility correction period t according to I _ds . For example, when I _ds is large, it is preferable to set the mobility correction period t shorter, and conversely, when I _ds becomes smaller, the mobility correction period t is set longer. In the example shown in FIG. 29, at least by putting edge of the video signal line potential, when the potential of the video signal line DTL101 is higher (when I _ds is large) correction period t is shortened, the video signal line DTL101 When the potential is low (when I _ds is small), the correction period t is automatically adjusted to be long.

FIG. 30 is a graph for explaining the operating point of the driving transistor 3B at the time of mobility correction. Optimal correction parameters ΔV and ΔV ′ are determined by applying the above-described mobility correction to the variations in mobility μ and μ ′ in the manufacturing process, and the drain-source currents I _ds and I d of the driving transistor 3B are determined. _ds ' is determined. If mobility correction is not applied, if the mobility is different between μ and μ ′ with respect to the gate-source voltage V _gs , the drain-source current is also corresponding to I _ds0 and I _ds0 ′. It will be different. In order to cope with this, by applying appropriate corrections ΔV and ΔV ′ to the mobility μ and μ ′, respectively, the drain-source current becomes I _ds and I _ds ′, which are the same level. As is clear from FIG. 30, negative feedback is applied so that the correction amount ΔV increases when the mobility μ is high, while the correction amount ΔV ′ decreases when the mobility μ ′ is small.

FIG. 31 is a graph showing current-voltage characteristics of the light-emitting element 3 </ b> D composed of organic EL elements. When the current I _el flows through the light emitting element 3D, the anode-cathode voltage V _el is uniquely determined. As shown in FIG. 25, when the scanning line WSL101 transits to the low potential side during the light emission period and the sampling transistor 3A is turned off, the anode of the light emitting element 3D is the drain-source current I _{ds of the} driving transistor 3B. It rises by the anode-cathode voltage V _el determined by

FIG. 32 is a graph showing potential fluctuations of the gate potential V _g and the source potential V _s of the driving transistor 3B when the anode potential of the light emitting element 3D is increased. When the anode voltage rise of the light-emitting device 3D is V _el, the source of the drive transistor 3B also increases by V _el, the gate of the drive transistor 3B by the bootstrap operation of the holding capacitor 3C also increases V _el min. For this reason, the gate-source voltage V _gs = V _in + V _th −ΔV of the driving transistor 3B held before the bootstrap is held as it is after the bootstrap. Even if the anode potential fluctuates due to deterioration over time of the light emitting element 3D, the gate-source voltage of the driving transistor 3B is always kept constant at V _in + V _th −ΔV.

FIG. 33 is a circuit diagram in which parasitic capacitances 7A and 7B are added to the pixel configuration described in FIG. The parasitic capacitances 7A and 7B are parasitic on the gate g of the driving transistor 3. The capacitance value of the bootstrap operation capacity of the above-mentioned hold capacitor C _s, the capacitance value of the parasitic capacitance 7A and 7B the C _w respectively, when the C _p, is represented by _{C s / (C s + C} w + C p) The closer this is to 1, the higher the bootstrap operation capability. In other words, the light-emitting element 3D has a high correction capability with respect to deterioration over time. In this display device, the number of elements connected to the gate g of the driving transistor 3B is kept to a minimum, and C _p can be almost ignored. Therefore, the bootstrap operation capability is represented by C _s / (C _s + C _w ), which is as close to 1 as possible, indicating that the correction capability for the temporal deterioration of the light emitting element 3D is high.

Next explained is an active matrix display device according to the fourth embodiment of the invention.
FIG. 34 is a schematic circuit diagram of this display device. In FIG. 32, parts corresponding to those of the display device according to the third embodiment shown in FIG. The difference is that the display device shown in FIG. 18 uses n-channel transistors to form pixels, whereas the display device shown in FIG. 34 uses p-channel transistors to form pixels. It is that you are. The pixel in FIG. 34 can perform the threshold voltage correction operation, the mobility correction operation, and the bootstrap operation in exactly the same manner as the pixel shown in FIG.
In this display device, the structure of the driving transistor 3B and the storage capacitor 3C made of thin film transistors among the elements included in the pixel is the same as that shown in FIG.

As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to the above-mentioned embodiment, The various deformation | transformation based on the technical idea of this invention is possible.
For example, the numerical values, arrangements, materials, structures, shapes, and the like given in the first to fourth embodiments are merely examples, and if necessary, different numerical values, arrangements, materials, structures, shapes, etc. May be used.

It is a block diagram which shows the display apparatus by a reference example. It is a schematic diagram which shows the pixel circuit taken out from the display apparatus shown in FIG. 3 is a timing chart for explaining the operation of the display device shown in FIGS. 1 and 2. 1 is a block diagram showing an overall configuration of a display device according to a first embodiment of the present invention. It is a block diagram which shows the structure of the pixel contained in the display apparatus by 1st Embodiment of this invention. FIG. 6 is a schematic diagram illustrating a pixel circuit cut out from the display device illustrated in FIG. 5. 6 is a timing chart for explaining the operation of the display device shown in FIGS. 4 and 5. 6 is a timing chart for explaining the operation of the display device shown in FIGS. 4 and 5. 6 is a timing chart for explaining the operation of the display device shown in FIGS. 4 and 5. 6 is a timing chart for explaining the operation of the display device shown in FIGS. 4 and 5. 6 is a graph for explaining the operation of the display device shown in FIGS. 4 and 5. It is sectional drawing which shows the structure of the principal part in the pixel of the display apparatus by 1st Embodiment of this invention. It is a schematic diagram with which it uses for description of the data driver in the display apparatus by 2nd Embodiment of this invention. It is a circuit diagram which shows the structural example of the data driver in the display apparatus by the 2nd Embodiment of this invention. It is a circuit diagram which shows the pixel structure of the display apparatus on the premise of description of the display apparatus by 3rd Embodiment of this invention. 16 is a timing chart for explaining the operation of the pixel shown in FIG. 15. It is a block diagram which shows the whole structure of the display apparatus by 3rd Embodiment of this invention. It is a circuit diagram which shows embodiment of the display apparatus by 3rd Embodiment of this invention. FIG. 19 is a timing chart for explaining the operation of the display device shown in FIG. 18. FIG. It is a circuit diagram with which it uses for operation | movement description of the display apparatus shown in FIG. It is a circuit diagram with which it uses for operation | movement description of the display apparatus shown in FIG. It is a circuit diagram with which it uses for operation | movement description of the display apparatus shown in FIG. It is a circuit diagram with which it uses for operation | movement description of the display apparatus shown in FIG. It is a circuit diagram with which it uses for operation | movement description of the display apparatus shown in FIG. It is a circuit diagram with which it uses for operation | movement description of the display apparatus shown in FIG. It is a graph which shows the current-voltage characteristic of the transistor for a drive. It is a graph which shows the current-voltage characteristic of the transistor for a drive. It is a circuit diagram with which it uses for operation | movement description of the display apparatus by 3rd Embodiment of this invention. It is a wave form diagram with which it uses for operation | movement description of the display apparatus by 3rd Embodiment of this invention. It is a current-voltage characteristic graph of the display apparatus by 3rd Embodiment of this invention. It is a graph which shows the current-voltage characteristic of a light emitting element. It is a wave form diagram which shows the bootstrap operation | movement of the transistor for a drive. It is a circuit diagram with which it uses for operation | movement description of the display apparatus by 3rd Embodiment of this invention. It is a circuit diagram which shows the display apparatus by 4th Embodiment of this invention. It is sectional drawing which shows the structure of the principal part of the pixel of the display apparatus which the present inventors examined.

Explanation of symbols

1 ... pixel array unit, 2 ... pixels, 3 ... horizontal selector, 4 ... write scanner, 5 ... drive scanner, Tr1 ... sampling transistor, Tr4 ... switching transistor, Trd ... driving transistor, C _s ... holding capacitor, EL ... Light emitting element, 51 ... Glass substrate, 52 ... Gate wiring, 53 ... Electrode, 54 ... Gate insulating film, 55 ... Polycrystalline silicon film, 58 ... Dielectric film, 100 ... Display device, 101 ... Pixel, 102 ... Pixel array section , 103 ... Horizontal selector, 104 ... Write scanner, 105 ... Power supply scanner, 3A ... Sampling transistor, 3B ... Driving transistor, 3C ... Holding capacitor, 3D ... Light emitting element

Claims (20)

A pixel array unit, a scanner unit, and a signal unit;
The pixel array unit includes a scanning line arranged in a row, a signal line arranged in a column, and a matrix pixel arranged in a portion where the scanning line and the signal line intersect,
The signal unit supplies a video signal to the signal line,
The scanner unit supplies a control signal to the first scanning line and the second scanning line to sequentially scan the pixels for each row,
The pixel includes a light emitting element, a sampling transistor made of a thin film transistor, a drive transistor made of a thin film transistor, a storage capacitor, and a switching transistor for connecting the drive transistor to a power source,
The sampling transistor is turned on in response to a control signal supplied from the first scanning line, samples the signal potential of the video signal supplied from the signal line in the holding capacitor,
The holding capacitor applies an input voltage to the gate of the driving transistor according to the signal potential of the sampled video signal,
The driving transistor supplies an output current corresponding to the input voltage to the light emitting element, and the output current has a dependency on a threshold voltage of the driving transistor,
The light emitting element emits light with a luminance corresponding to the signal potential of the video signal by an output current supplied from the driving transistor during a light emission period,
The switching transistor is turned on in response to a control signal supplied from the second scanning line, connects the driving transistor to a power source during the light emission period, and becomes non-conductive during the non-light emission period. Disconnect from the power supply,
The scanner unit outputs a control signal to the first scanning line and the second scanning line in a horizontal scanning period, controls on / off of the sampling transistor and the switching transistor, and controls the threshold of the output current. Preparation operation for resetting the storage capacitor to correct the dependency on the value voltage, correction operation for writing a voltage for canceling the threshold voltage to the reset storage capacitor, and the corrected storage capacitor A display device configured to perform a sampling operation for sampling the signal potential of the video signal,
The display device, wherein the gate insulating film of the driving transistor and the dielectric film constituting the storage capacitor are formed independently of each other.   The signal unit switches the video signal between the first fixed potential, the second fixed potential, and the signal potential during the horizontal scanning period, thereby changing the potential necessary for the preparation operation, the correction operation, and the sampling operation. The display device according to claim 1, wherein the display device is configured to be supplied to each pixel through the signal line.   The signal unit first supplies the first fixed potential at a high level, then switches to the second fixed potential at a low level to enable the preparatory operation, and further maintains the second fixed potential at a low level. 3. The display device according to claim 2, wherein the correction operation is executed in a state, and then the sampling operation is executed by switching to the signal potential.   The signal unit inserts the first fixed potential and the second fixed potential into the signal potential output from the signal generation circuit that generates the signal potential and the signal generation circuit, and thereby the first fixed potential. 3. A display device according to claim 2, further comprising: an output circuit that synthesizes a video signal in which the second fixed potential and the signal potential are switched and outputs the synthesized video signal to the signal line. The driving transistor has an output current dependent on the carrier mobility of the channel region in addition to the threshold voltage,
The scanner unit outputs a control signal to the second scanning line in the horizontal scanning period to further control the switching transistor, and the signal potential is sampled in order to cancel the dependence of the output current on the carrier mobility. 2. An operation for taking out an output current from the driving transistor in a state in which the output current is applied and negatively feeding back the output current to the holding capacitor to correct the input voltage. The display device according to 1. A pixel array unit, a scanner unit, and a signal unit;
The pixel array unit includes a scanning line arranged in a row, a signal line arranged in a column, and a matrix pixel arranged in a portion where the scanning line and the signal line intersect,
The signal unit supplies a video signal to the signal line,
The scanner unit supplies a control signal to the first scanning line and the second scanning line to sequentially scan the pixels for each row,
The pixel includes a light emitting element, a sampling transistor made of a thin film transistor, a drive transistor made of a thin film transistor, a storage capacitor, and a switching transistor for connecting the drive transistor to a power source,
A driving method of a display device in which a gate insulating film of the driving transistor and a dielectric film constituting the storage capacitor are formed independently of each other,
The sampling transistor is turned on in response to a control signal supplied from the first scanning line, and samples the signal potential of the video signal supplied from the signal line in the storage capacitor;
The holding capacitor applies an input voltage to the gate of the driving transistor according to the signal potential of the sampled video signal,
The driving transistor supplies an output current corresponding to the input voltage to the light emitting element, and the output current has a dependency on a threshold voltage of the driving transistor,
The light emitting element emits light with a luminance corresponding to the signal potential of the video signal by an output current supplied from the driving transistor during a light emission period,
The switching transistor is turned on in response to a control signal supplied from the second scanning line, connects the driving transistor to a power source during the light emission period, and becomes non-conductive during the non-light emission period. Disconnect from the power supply,
The scanner unit outputs a control signal to the first scanning line and the second scanning line in a horizontal scanning period, controls on / off of the sampling transistor and the switching transistor, and controls the threshold of the output current. Preparation operation for resetting the storage capacitor to correct the dependency on the value voltage, correction operation for writing a voltage for canceling the threshold voltage to the reset storage capacitor, and the corrected storage capacitor And a sampling operation for sampling a signal potential of the video signal. A pixel array unit, a scanner unit, and a drive unit;
The pixel array unit includes a scanning line arranged in a row, a signal line arranged in a column, and a matrix pixel arranged in a portion where the scanning line and the signal line intersect,
The driving unit supplies a video signal to the signal line,
The scanner unit supplies a control signal to the first scanning line and the second scanning line to sequentially scan the pixels for each row,
The pixel includes a light emitting element, a sampling transistor made of a thin film transistor, a drive transistor made of a thin film transistor, a storage capacitor, and a switching transistor for connecting the drive transistor to a power source,
The sampling transistor is turned on in response to a control signal supplied from the first scanning line, and samples the signal potential of the video signal supplied from the signal line in the holding capacitor,
The holding capacitor applies an input voltage to the gate of the driving transistor according to the signal potential of the sampled video signal,
The driving transistor supplies an output current corresponding to the input voltage to the light emitting element,
The light emitting element emits light with a luminance corresponding to the signal potential of the video signal by an output current supplied from the driving transistor during a light emission period,
The switching transistor is turned on in response to a control signal supplied from the second scan line, connects the driving transistor to a power source during the light emission period, and becomes non-conductive during a non-light emission period, Disconnect the transistor from the power supply,
The scanner unit outputs a control signal to the first scanning line and the second scanning line, respectively, during a horizontal scanning period, and controls on / off of the sampling transistor and the switching transistor, thereby varying the output current. Perform a correction operation to correct and a sampling operation to sample the signal potential of the video signal,
The driver unit switches the video signal between a fixed potential and a signal potential during the horizontal scanning period, and thereby supplies a potential necessary for the correction operation and the sampling operation to the pixel via the signal line. A display device configured as follows:
The display device, wherein the gate insulating film of the driving transistor and the dielectric film constituting the storage capacitor are formed independently of each other. Including a pixel array unit and a drive unit,
The pixel array section corresponds to a scanning line arranged in a row, a signal line arranged in a column, a matrix pixel arranged in a portion where the scanning line and the signal line intersect, and each row of the pixel. Power line arranged
The driving unit supplies a control signal to the scanning lines sequentially to scan the pixels line-by-line in units of rows, and applies a first potential and a second potential to the power supply line in accordance with the line sequential scanning. A power supply scanner that supplies a power supply voltage that is switched between, and a signal selector that supplies a signal potential and a reference potential to be a video signal to the signal line in accordance with the line sequential scanning,
The pixel includes a light emitting element, a sampling transistor including a thin film transistor, a driving transistor including a thin film transistor, and a storage capacitor.
The sampling transistor has its gate connected to the scanning line, one of its source and drain connected to the signal line, and the other connected to the gate of the driving transistor,
The driving transistor has one of a source and a drain connected to the light emitting element, the other connected to the power supply line,
The storage capacitor is connected between a source and a gate of the driving transistor,
The sampling transistor is turned on in response to a control signal supplied from the scanning line, samples the signal potential supplied from the signal line, and holds it in the storage capacitor,
The driving transistor receives a supply of current from the power supply line at the first potential, and causes a driving current to flow to the light emitting element according to the held signal potential.
The power supply scanner switches the power supply line between the first potential and the second potential while the signal selector supplies a reference potential to the signal line after the sampling transistor is turned on. The display device is configured to hold a voltage corresponding to the threshold voltage of the driving transistor in the holding capacitor.
The display device, wherein the gate insulating film of the driving transistor and the dielectric film constituting the storage capacitor are formed independently of each other. The signal selector switches the signal line from a reference potential to a signal potential at a first timing after the sampling transistor is turned on,
The main scanner cancels the application of the control signal to the scanning line at the second timing after the first timing to make the sampling transistor non-conductive,
By appropriately setting a period between the first timing and the second timing, when the signal potential is held in the storage capacitor, the correction for the carrier mobility in the channel region of the driving transistor is performed. The display device according to claim 8, wherein the display device is configured to be applied to a signal potential.   The drive unit adjusts a relative phase difference between the video signal supplied from the signal selector and the control signal supplied from the main scanner, and a period between the first timing and the second timing. The display device according to claim 9, wherein the display device is optimized.   The signal selector is configured to incline the rising edge of the video signal switching from the reference potential to the signal potential so that the period between the first timing and the second timing follows the signal potential. The display device according to claim 9.   The main scanner cancels the application of the control signal to the scanning line at the stage where the signal potential is held in the holding capacitor, makes the sampling transistor non-conductive, and connects the gate of the driving transistor from the signal line. 10. The device according to claim 9, wherein the voltage is electrically disconnected, and the voltage between the gate and the source is maintained constant in association with the fluctuation of the source potential of the driving transistor. The display device described. Including a pixel array unit and a drive unit,
The pixel array section corresponds to a scanning line arranged in a row, a signal line arranged in a column, a matrix pixel arranged in a portion where the scanning line and the signal line intersect, and each row of the pixel. Power line arranged
The driving unit supplies a control signal to the scanning lines sequentially to scan the pixels line by line, and the power supply line is supplied with a first potential and a second potential in accordance with the line sequential scanning. A power supply scanner that supplies a power supply voltage that is switched between, and a signal selector that supplies a signal potential and a reference potential to be a video signal to the signal line in accordance with the line sequential scanning,
The pixel includes a light emitting element, a sampling transistor including a thin film transistor, a driving transistor including a thin film transistor, and a storage capacitor.
The sampling transistor has its gate connected to the scanning line, one of its source and drain connected to the signal line, and the other connected to the gate of the driving transistor,
The driving transistor has one of a source and a drain connected to the light emitting element, the other connected to the power supply line,
The storage capacitor is connected between the source and gate of the driving transistor,
A driving method of a display device in which a gate insulating film of the driving transistor and a dielectric film constituting the storage capacitor are formed independently of each other,
The sampling transistor is turned on in response to a control signal supplied from the scanning line, samples the signal potential supplied from the signal line, and holds it in the storage capacitor;
The driving transistor receives a current supplied from the power supply line at the first potential, and causes a driving current to flow to the light emitting element in accordance with the held signal potential;
The power supply scanner switches the power supply line between the first potential and the second potential while the signal selector supplies a reference potential to the signal line after the sampling transistor is turned on. Thus, a voltage corresponding to the threshold voltage of the driving transistor is held in the holding capacitor. Including a pixel array unit and a drive unit,
The pixel array section corresponds to a scanning line arranged in a row, a signal line arranged in a column, a matrix pixel arranged in a portion where the scanning line and the signal line intersect, and each row of the pixel. Power line arranged
The driving unit supplies a control signal to the scanning lines sequentially to scan the pixels line by line, and the power supply line is supplied with a first potential and a second potential in accordance with the line sequential scanning. A power supply scanner that supplies a power supply voltage that is switched between, and a signal selector that supplies a signal potential and a reference potential to be a video signal to the signal line in accordance with the line sequential scanning,
The pixel includes a light emitting element, a sampling transistor including a thin film transistor, a driving transistor including a thin film transistor, and a storage capacitor.
The sampling transistor has its gate connected to the scanning line, one of its source and drain connected to the signal line, and the other connected to the gate of the driving transistor,
The driving transistor has one of a source and a drain connected to the light emitting element, the other connected to the power supply line,
The storage capacitor is connected between a source and a gate of the driving transistor,
The sampling transistor is turned on in response to a control signal supplied from the scanning line, samples the signal potential supplied from the signal line, and holds it in the storage capacitor,
The driving transistor receives a supply of current from the power supply line at the first potential, and causes a driving current to flow to the light emitting element according to the held signal potential,
The signal selector switches the signal line from a reference potential to a signal potential at a first timing after the sampling transistor is turned on,
The main scanner cancels the application of the control signal to the scanning line at the second timing after the first timing to make the sampling transistor non-conductive,
By appropriately setting the period between the first timing and the second timing, when the signal potential is held in the storage capacitor, the correction for the carrier mobility in the channel region of the driving transistor is performed as a signal. A display device configured to apply an electric potential,
The display device, wherein the gate insulating film of the driving transistor and the dielectric film constituting the storage capacitor are formed independently of each other. Including a pixel array unit and a drive unit,
The pixel array section corresponds to a scanning line arranged in a row, a signal line arranged in a column, a matrix pixel arranged in a portion where the scanning line and the signal line intersect, and each row of the pixel. Power line arranged
The driving unit supplies a control signal to the scanning lines sequentially to scan the pixels line by line, and the power supply line is supplied with a first potential and a second potential in accordance with the line sequential scanning. A power supply scanner that supplies a power supply voltage that is switched between, and a signal selector that supplies a signal potential and a reference potential to be a video signal to the signal line in accordance with the line sequential scanning,
The pixel includes a light emitting element, a sampling transistor including a thin film transistor, a driving transistor including a thin film transistor, and a storage capacitor.
The sampling transistor has its gate connected to the scanning line, one of its source and drain connected to the signal line, and the other connected to the gate of the driving transistor,
The driving transistor has one of a source and a drain connected to the light emitting element, the other connected to the power supply line,
The storage capacitor is connected between the source and gate of the driving transistor,
A driving method of a display device in which a gate insulating film of the driving transistor and a dielectric film constituting the storage capacitor are formed independently of each other,
The sampling transistor is turned on in response to a control signal supplied from the scanning line, samples the signal potential supplied from the signal line, and holds it in the storage capacitor;
The driving transistor receives a current supplied from the power supply line at the first potential, and causes a driving current to flow to the light emitting element in accordance with the held signal potential;
The signal selector switches the signal line from a reference potential to a signal potential at a first timing after the sampling transistor is turned on,
The main scanner cancels the application of the control signal to the scanning line at the second timing after the first timing to make the sampling transistor non-conductive,
By appropriately setting a period between the first timing and the second timing, when the signal potential is held in the storage capacitor, correction for the carrier mobility in the channel region of the driving transistor is performed as a signal. A method for driving a display device, characterized by applying to a potential. An active matrix display device in which a pixel includes a light emitting element, a sampling transistor including a thin film transistor, a driving thin film transistor including a thin film transistor, and a storage capacitor,
The display device, wherein the gate insulating film of the driving transistor and the dielectric film constituting the storage capacitor are formed independently of each other. In an electronic device having one or more display devices,
At least one of the display devices,
A pixel array unit, a scanner unit, and a signal unit;
The pixel array unit includes a scanning line arranged in a row, a signal line arranged in a column, and a matrix pixel arranged in a portion where the scanning line and the signal line intersect,
The signal unit supplies a video signal to the signal line,
The scanner unit supplies a control signal to the first scanning line and the second scanning line to sequentially scan the pixels for each row,
The pixel includes a light emitting element, a sampling transistor made of a thin film transistor, a drive transistor made of a thin film transistor, a storage capacitor, and a switching transistor for connecting the drive transistor to a power source,
The sampling transistor is turned on in response to a control signal supplied from the first scanning line, samples the signal potential of the video signal supplied from the signal line in the holding capacitor,
The holding capacitor applies an input voltage to the gate of the driving transistor according to the signal potential of the sampled video signal,
The driving transistor supplies an output current corresponding to the input voltage to the light emitting element, and the output current has a dependency on a threshold voltage of the driving transistor,
The light emitting element emits light with a luminance corresponding to the signal potential of the video signal by an output current supplied from the driving transistor during a light emission period,
The switching transistor is turned on in response to a control signal supplied from the second scanning line, connects the driving transistor to a power source during the light emission period, and becomes non-conductive during the non-light emission period. Disconnect from the power supply,
The scanner unit outputs a control signal to the first scanning line and the second scanning line in a horizontal scanning period, controls on / off of the sampling transistor and the switching transistor, and controls the threshold of the output current. Preparation operation for resetting the storage capacitor to correct the dependency on the value voltage, correction operation for writing a voltage for canceling the threshold voltage to the reset storage capacitor, and the corrected storage capacitor A display device configured to perform a sampling operation for sampling the signal potential of the video signal,
An electronic apparatus, wherein a gate insulating film of the driving transistor and a dielectric film constituting the storage capacitor are formed independently of each other. In an electronic device having one or more display devices,
At least one of the display devices,
A pixel array unit, a scanner unit, and a drive unit;
The pixel array unit includes a scanning line arranged in a row, a signal line arranged in a column, and a matrix pixel arranged in a portion where the scanning line and the signal line intersect,
The driving unit supplies a video signal to the signal line,
The scanner unit supplies a control signal to the first scanning line and the second scanning line to sequentially scan the pixels for each row,
The pixel includes a light emitting element, a sampling transistor made of a thin film transistor, a drive transistor made of a thin film transistor, a storage capacitor, and a switching transistor for connecting the drive transistor to a power source,
The sampling transistor is turned on in response to a control signal supplied from the first scanning line, and samples the signal potential of the video signal supplied from the signal line in the holding capacitor,
The holding capacitor applies an input voltage to the gate of the driving transistor according to the signal potential of the sampled video signal,
The driving transistor supplies an output current corresponding to the input voltage to the light emitting element,
The light emitting element emits light with a luminance corresponding to the signal potential of the video signal by an output current supplied from the driving transistor during a light emission period,
The switching transistor is turned on in response to a control signal supplied from the second scan line, connects the driving transistor to a power source during the light emission period, and becomes non-conductive during a non-light emission period, Disconnect the transistor from the power supply,
The scanner unit outputs a control signal to the first scanning line and the second scanning line, respectively, during a horizontal scanning period, and controls on / off of the sampling transistor and the switching transistor, thereby varying the output current. Perform a correction operation to correct and a sampling operation to sample the signal potential of the video signal,
The driver unit switches the video signal between a fixed potential and a signal potential during the horizontal scanning period, and thereby supplies a potential necessary for the correction operation and the sampling operation to the pixel via the signal line. A display device configured as follows:
An electronic apparatus, wherein a gate insulating film of the driving transistor and a dielectric film constituting the storage capacitor are formed independently of each other. In an electronic device having one or more display devices,
At least one of the display devices,
Including a pixel array unit and a drive unit,
The pixel array section corresponds to a scanning line arranged in a row, a signal line arranged in a column, a matrix pixel arranged in a portion where the scanning line and the signal line intersect, and each row of the pixel. Power line arranged
The driving unit supplies a control signal to the scanning lines sequentially to scan the pixels line by line, and the power supply line is supplied with a first potential and a second potential in accordance with the line sequential scanning. A power supply scanner that supplies a power supply voltage that is switched between, and a signal selector that supplies a signal potential and a reference potential to be a video signal to the signal line in accordance with the line sequential scanning,
The pixel includes a light emitting element, a sampling transistor including a thin film transistor, a driving transistor including a thin film transistor, and a storage capacitor.
The sampling transistor has its gate connected to the scanning line, one of its source and drain connected to the signal line, and the other connected to the gate of the driving transistor,
The driving transistor has one of a source and a drain connected to the light emitting element, the other connected to the power supply line,
The storage capacitor is connected between a source and a gate of the driving transistor,
The sampling transistor is turned on in response to a control signal supplied from the scanning line, samples the signal potential supplied from the signal line, and holds it in the storage capacitor,
The driving transistor receives a supply of current from the power supply line at the first potential, and causes a driving current to flow to the light emitting element according to the held signal potential,
The signal selector switches the signal line from a reference potential to a signal potential at a first timing after the sampling transistor is turned on,
The main scanner cancels the application of the control signal to the scanning line at the second timing after the first timing to make the sampling transistor non-conductive,
By appropriately setting the period between the first timing and the second timing, when the signal potential is held in the storage capacitor, the correction for the carrier mobility in the channel region of the driving transistor is performed as a signal. A display device configured to apply an electric potential,
An electronic apparatus, wherein a gate insulating film of the driving transistor and a dielectric film constituting the storage capacitor are formed independently of each other. In an electronic device having one or more display devices,
At least one of the display devices,
Including a pixel array unit and a drive unit,
The pixel array section corresponds to a scanning line arranged in a row, a signal line arranged in a column, a matrix pixel arranged in a portion where the scanning line and the signal line intersect, and each row of the pixel. Power line arranged
The driving unit supplies a control signal to the scanning lines sequentially to scan the pixels line by line, and the power supply line is supplied with a first potential and a second potential in accordance with the line sequential scanning. A power supply scanner that supplies a power supply voltage that is switched between, and a signal selector that supplies a signal potential and a reference potential to be a video signal to the signal line in accordance with the line sequential scanning,
The pixel includes a light emitting element, a sampling transistor including a thin film transistor, a driving transistor including a thin film transistor, and a storage capacitor.
The sampling transistor has its gate connected to the scanning line, one of its source and drain connected to the signal line, and the other connected to the gate of the driving transistor,
The driving transistor has one of a source and a drain connected to the light emitting element, the other connected to the power supply line,
The storage capacitor is connected between a source and a gate of the driving transistor,
The sampling transistor is turned on in response to a control signal supplied from the scanning line, samples the signal potential supplied from the signal line, and holds it in the storage capacitor,
The driving transistor receives a supply of current from the power supply line at the first potential, and causes a driving current to flow to the light emitting element according to the held signal potential,
The signal selector switches the signal line from a reference potential to a signal potential at a first timing after the sampling transistor is turned on,
The main scanner cancels the application of the control signal to the scanning line at the second timing after the first timing to make the sampling transistor non-conductive,
By appropriately setting the period between the first timing and the second timing, when the signal potential is held in the storage capacitor, the correction for the carrier mobility in the channel region of the driving transistor is performed as a signal. A display device configured to apply an electric potential,
An electronic apparatus, wherein a gate insulating film of the driving transistor and a dielectric film constituting the storage capacitor are formed independently of each other.

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