Sony Patent | Display Device, Display Device Driving Method, Display Element, And Electronic Apparatus
Patent: Display Device, Display Device Driving Method, Display Element, And Electronic Apparatus
Publication Number: 20200168152
Publication Date: 20200528
Applicants: Sony
Abstract
The display element includes: a current-driven light-emitting unit; a capacitor unit including a first capacitor and a second capacitor; an n-channel driving transistor that causes a current corresponding to a voltage held by the capacitor unit to flow through the light-emitting unit; and a first switching transistor that writes a video signal voltage to the capacitor unit. In a state in which the first capacitor holds a voltage corresponding to a threshold voltage of the driving transistor, a video signal voltage is written to the second capacitor through the first switching transistor in a conducting state.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation application of U.S. patent application Ser. No. 15/768,134, filed Apr. 13, 2018, which is a national stage entry of PCT/JP2016/073930, filed Aug. 16, 2016, which claims priority from prior Japanese Priority Patent Application JP 2015-210650 filed in the Japan Patent Office on Oct. 27, 2015, the entire contents of which are hereby incorporated by reference.
TECHNICAL FIELD
[0002] The present disclosure relates to a display device, a display device driving method, a display element, and an electronic apparatus.
BACKGROUND ART
[0003] A display element provided with a current-driven light-emitting unit, and a display device provided with the display element, are well known. For example, a display element provided with a light-emitting unit that uses electroluminescence of an organic material (hereinafter, may be merely referred to as “organic EL display element”) attracts attention as a display element that is capable of high-luminance light emission by low-voltage DC driving.
[0004] As with liquid crystal display devices, in the field of, for example, display devices, each of which is provided with an organic EL display element, as well, a simple matrix method and an active matrix method are well known as driving methods. The active matrix method has a disadvantage that a structure becomes complicated. However, the active matrix method has, for example, an advantage that the brightness of an image can be made high. An organic EL display element driven by the active matrix method is provided with not only a light-emitting unit that includes an organic layer including a light-emitting layer and the like, but also a driving circuit having a driving transistor for driving the light-emitting unit.
[0005] A value of a current flowing through the driving transistor is influenced not only by a voltage of a gate electrode with respect to a source region of the driving transistor (so-called a voltage between the gate and the source) but also by a threshold voltage of the driving transistor. The threshold voltage of the driving transistor disperses on a display element basis, and therefore causes uneven brightness. For example, Japanese Patent Application Laid-Open No. 2008-287139 (Patent Document 1) discloses the feature of performing the operation of canceling an influence, which is exerted by the dispersion in threshold voltage of a driving transistor, every time a video signal is written to a display element.
CITATION LIST
Patent Document
[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2008-287139
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0007] The operation of canceling the influence, which is exerted by the dispersion in threshold voltage of a driving transistor, every time a video signal is written becomes a factor for increasing the power consumption of a display device. In general, the power consumption of an electronic apparatus is desired to be low. Accordingly, a reduction in power consumption of a display device is also expected.
[0008] Therefore, an object of the present invention is to provide: a display device that is capable of further reducing the power consumption while canceling an influence exerted by the dispersion in threshold voltage of a driving transistor; a method for driving the display device; a display element; and an electronic apparatus.
Solutions to Problems
[0009] In order to achieve the above-described object, a display device according to the present disclosure includes: a display unit in which display elements are arranged; and a drive unit for driving the display unit, in which:
[0010] the display elements each include: a current-driven light-emitting unit; a capacitor unit including a first capacitor and a second capacitor; an n-channel driving transistor that causes a current corresponding to a voltage held by the capacitor unit to flow through the light-emitting unit; and a first switching transistor that writes a video signal voltage to the capacitor unit;
[0011] in the capacitor unit, one end of the first capacitor is connected to a gate electrode of the driving transistor to form a first node, the other end of the first capacitor is connected to one end of the second capacitor to form a second node, and the other end of the second capacitor is connected to one end of the light-emitting unit, and to the other source/drain region of the driving transistor to form a third node;
[0012] in the driving transistor, one source/drain region is connected to an electric supply line, and the other source/drain region is connected to the light-emitting unit;
[0013] in the first switching transistor, one source/drain region is connected to a data line, and the other source/drain region is connected to the third node;* and*
[0014] in a state in which the first capacitor holds a voltage corresponding to a threshold voltage of the driving transistor, the drive unit writes a video signal voltage to the second capacitor through the first switching transistor in a conducting state.
[0015] In order to achieve the above-described object, there is provided a method for driving a display device according to the present disclosure, the display device including: a display unit in which display elements are arranged; and a drive unit for driving the display unit, in which:
[0016] the display elements each include: a current-driven light-emitting unit; a capacitor unit including a first capacitor and a second capacitor; an n-channel driving transistor that causes a current corresponding to a voltage held by the capacitor unit to flow through the light-emitting unit; and a first switching transistor that writes a video signal voltage to the capacitor unit;
[0017] in the capacitor unit, one end of the first capacitor is connected to a gate electrode of the driving transistor to form a first node, the other end of the first capacitor is connected to one end of the second capacitor to form a second node, and the other end of the second capacitor is connected to one end of the light-emitting unit, and to the other source/drain region of the driving transistor to form a third node;
[0018] in the driving transistor, one source/drain region is connected to an electric supply line, and the other source/drain region is connected to the light-emitting unit;
[0019] in the first switching transistor, one source/drain region is connected to a data line, and the other source/drain region is connected to the third node;* and*
[0020] in a state in which the first capacitor holds a voltage corresponding to a threshold voltage of the driving transistor, the drive unit writes a video signal voltage to the second capacitor through the first switching transistor in a conducting state.
[0021] In order to achieve the above-described object, a display element according to the present disclosure includes:
[0022] a current-driven light-emitting unit; a capacitor unit including a first capacitor and a second capacitor; an n-channel driving transistor that causes a current corresponding to a voltage held by the capacitor unit to flow through the light-emitting unit; and a first switching transistor that writes a video signal voltage to the capacitor unit; in which:
[0023] in the capacitor unit, one end of the first capacitor is connected to a gate electrode of the driving transistor to form a first node, the other end of the first capacitor is connected to one end of the second capacitor to form a second node, and the other end of the second capacitor is connected to one end of the light-emitting unit, and to the other source/drain region of the driving transistor to form a third node;
[0024] in the driving transistor, one source/drain region is connected to an electric supply line, and the other source/drain region is connected to the light-emitting unit;
[0025] in the first switching transistor, one source/drain region is connected to a data line, and the other source/drain region is connected to the third node;* and*
[0026] in a state in which the first capacitor holds a voltage corresponding to a threshold voltage of the driving transistor, a video signal voltage is written to the second capacitor through the first switching transistor in a conducting state.
[0027] In order to achieve the above-described object, an electronic apparatus according to the present disclosure includes a display device, in which:
[0028] the display device includes: a display unit in which display elements are arranged; and a drive unit for driving the display unit;
[0029] the display elements each include: a current-driven light-emitting unit; a capacitor unit including a first capacitor and a second capacitor; an n-channel driving transistor that causes a current corresponding to a voltage held by the capacitor unit to flow through the light-emitting unit; and a first switching transistor that writes a video signal voltage to the capacitor unit;
[0030] in the capacitor unit, one end of the first capacitor is connected to a gate electrode of the driving transistor to form a first node, the other end of the first capacitor is connected to one end of the second capacitor to form a second node, and the other end of the second capacitor is connected to one end of the light-emitting unit, and to the other source/drain region of the driving transistor to form a third node;
[0031] in the driving transistor, one source/drain region is connected to an electric supply line, and the other source/drain region is connected to the light-emitting unit;
[0032] in the first switching transistor, one source/drain region is connected to a data line, and the other source/drain region is connected to the third node;* and*
[0033] in a state in which the first capacitor holds a voltage corresponding to a threshold voltage of the driving transistor, the drive unit writes a video signal voltage to the second capacitor through the first switching transistor in a conducting state.
Effects of the Invention
[0034] In the display device, the display device driving method, the display element, and the electronic apparatus according to the present disclosure, in a state in which the first capacitor holds a voltage corresponding to a threshold voltage of the driving transistor, a video signal voltage is written to the second capacitor through the first switching transistor in a conducting state. This enables a frequency of operations of holding, in the first capacitor, a voltage corresponding to a threshold voltage of the driving transistor to be reduced. Therefore, the power consumption can be further reduced while canceling an influence exerted by the dispersion in threshold voltage of the driving transistor. It should be noted that the effects described herein are not necessarily limited, and may be any one of the effects described in the present disclosure.
BRIEF DESCRIPTION OF DRAWINGS
[0035] FIG. 1 is a conceptual diagram illustrating a display device according to a first embodiment.
[0036] FIG. 2 is a schematic partial cross-sectional view illustrating a part including a display element in the display unit.
[0037] FIG. 3 is a schematic timing chart illustrating the operation of the display device according to the first embodiment, more specifically, the operation of the (n, m)th display element of the display device.
[0038] FIGS. 4A and 4B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in a driving circuit of the display element of the display device according to the first embodiment.
[0039] Following FIGS. 4B, 5A, and 5B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the first embodiment.
[0040] Following FIGS. 5B, 6A, and 6B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the first embodiment.
[0041] Following FIGS. 6B, 7A, and 7B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the first embodiment.
[0042] Following FIGS. 7B, 8A, and 8B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the first embodiment.
[0043] FIG. 9 is a schematic timing chart illustrating the operation of a display device according to a second embodiment, more specifically, the operation of the (n, m)th display element of the display device.
[0044] FIGS. 10A and 10B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in a driving circuit of the display element of the display device according to the second embodiment.
[0045] FIG. 11 is a conceptual diagram illustrating a display device according to a third embodiment.
[0046] FIG. 12 is a schematic timing chart illustrating the operation of the display device according to the third embodiment, more specifically, the operation of the (n, m)th display element of the display device.
[0047] FIGS. 13A and 13B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in a driving circuit of the display element of the display device according to the third embodiment.
[0048] Following FIGS. 13B, 14A, and 14B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the third embodiment.
[0049] Following FIGS. 14B, 15A, and 15B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the third embodiment.
[0050] Following FIGS. 15B, 16A, and 16B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the third embodiment.
[0051] Following FIGS. 16B, 17A, and 17B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the third embodiment.
[0052] FIG. 18 is a conceptual diagram illustrating a display device according to a fourth embodiment.
[0053] FIG. 19 is a schematic timing chart illustrating the operation of the display device according to the fourth embodiment, more specifically, the operation of the (n, m)th display element of the display device.
[0054] FIGS. 20A and 20B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in a driving circuit of the display element of the display device according to the fourth embodiment.
[0055] Following FIGS. 20B, 21A, and 21B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the fourth embodiment.
[0056] Following FIGS. 21B, 22A, and 22B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the fourth embodiment.
[0057] Following FIGS. 22B, 23A, and 23B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the fourth embodiment.
[0058] Following FIGS. 23B, 24A, and 24B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the fourth embodiment.
[0059] FIG. 25 is a conceptual diagram illustrating a display device according to a fifth embodiment.
[0060] FIG. 26 is a schematic timing chart illustrating the operation of the display device according to the fifth embodiment, more specifically, the operation of the (n, m)th display element of the display device.
[0061] FIGS. 27A and 27B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in a driving circuit of the display element of the display device according to the fifth embodiment.
[0062] Following FIGS. 27B, 28A, and 28B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the fifth embodiment.
[0063] Following FIGS. 28B, 29A, and 29B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the fifth embodiment.
[0064] Following FIGS. 29B, 30A, and 30B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the fifth embodiment.
[0065] Following FIGS. 30B, 31A, and 31B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the fifth embodiment.
[0066] FIG. 32 is a schematic timing chart illustrating the operation of a display device according to a sixth embodiment, more specifically, the operation of the (n, m)th display element of the display device.
[0067] FIGS. 33A and 33B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in a driving circuit of the display element of the display device according to the sixth embodiment.
[0068] FIG. 34 is a conceptual diagram illustrating a display device according to a seventh embodiment.
[0069] FIG. 35 is a schematic timing chart illustrating the operation of the display device according to the seventh embodiment, more specifically, the operation of the (n, m)th display element of the display device.
[0070] FIGS. 36A and 36B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in a driving circuit of the display element of the display device according to the seventh embodiment.
[0071] Following FIGS. 36B, 37A, and 37B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the seventh embodiment.
[0072] Following FIGS. 37B, 38A, and 38B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the seventh embodiment.
[0073] Following FIGS. 38B, 39A, and 39B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the seventh embodiment.
[0074] Following FIGS. 39B, 40A, and, 40B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the seventh embodiment.
[0075] FIG. 41 is a conceptual diagram illustrating a display device according to an eighth embodiment.
[0076] FIG. 42 is a schematic timing chart illustrating the operation of the display device according to the eighth embodiment, more specifically, the operation of the (n, m)th display element of the display device.
[0077] FIGS. 43A and 43B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in a driving circuit of the display element of the display device according to the eighth embodiment.
[0078] Following FIGS. 43B, 44A, and 44B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the eighth embodiment.
[0079] Following FIGS. 44B, 45A and, 45B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the eighth embodiment.
[0080] Following FIGS. 45B, 46A, and 46B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the eighth embodiment.
[0081] Following FIGS. 46B, 47A, and 47B are drawings each schematically illustrating conducting state/non-conducting state and the like of each transistor that is included in the driving circuit of the display element of the display device according to the eighth embodiment.
[0082] FIG. 48 is a conceptual diagram illustrating a display device according to a first modified example.
[0083] FIG. 49 is a schematic timing chart illustrating the operation of the display device according to the first modified example, more specifically, the operation of the (n, m)th display element of the display device.
[0084] FIG. 50 is a conceptual diagram illustrating a display device according to a second modified example.
[0085] FIGS. 51A and 51B show outside drawings of a lens-interchangeable single-lens reflex type digital still camera, FIG. 51A is a front view thereof, and FIG. 51B is a rear view thereof.
[0086] FIG. 52 is an outside drawing of a head mounted display.
[0087] FIG. 53 is an outside drawing illustrating a see-through head mounted display.
MODE FOR CARRYING OUT THE INVENTION
[0088] The present disclosure will be described below on the basis of embodiments with reference to the accompanying drawings. The present disclosure is not limited to the embodiments, and various numerical values and materials in the embodiments are merely examples. In the following explanations, the same element, or an element having the same function, uses the same reference numeral, and overlapping explanation will be omitted. It should be noted that explanations are made in the following order.
-
Overall explanation about a display device, a display device driving method, a display element,* and an electronic apparatus according to the present disclosure*
2.* First Embodiment*
3.* Second Embodiment*
4.* Third Embodiment*
5.* Fourth Embodiment*
6.* Fifth Embodiment*
7.* Sixth Embodiment*
8.* Seventh Embodiment*
9.* Eighth Embodiment*
[0089] 10. Display device according to modified examples 11. Explanation of electronic apparatus,* and others*
[0090] Overall explanation about a display device, a display device driving method, a display element,* and an electronic apparatus according to the present disclosure*
[0091] In a display device, a display device driving method, and an electronic apparatus according to the present disclosure, a drive unit can be configured to scan display elements of a display unit consecutively, and to perform the operation of holding, in a first capacitor, a voltage corresponding to a threshold voltage of a driving transistor in a part of a plurality of consecutive frames.
[0092] The above-described operation may be performed, for example, once every two frames, or once every five or ten frames. From the viewpoint of reducing the power consumption, it is preferable to reduce a frequency of frames in which the operation of holding a voltage corresponding to the threshold voltage of the driving transistor in the first capacitor is performed. Meanwhile, the voltage held in the first capacitor changes due to leakage or the like. Therefore, from the viewpoint of, for example, reducing uneven brightness, it is preferable to maintain a certain level of frequency. A level of frequency may be set as appropriate according to, for example, specifications of the display device.
[0093] The operation of holding a voltage corresponding to the threshold voltage of the driving transistor in the first capacitor, and the operation of writing a video signal may be performed in some specific frame.
[0094] Alternatively, the following operation may be performed: in some specific frame, for all display elements, performing only the operation of holding a voltage corresponding to the threshold voltage of the driving transistor in the first capacitor; and in the subsequent frame, performing the operation of writing a video signal.
[0095] There is also a possibility that the voltage held by the first capacitor will change due to leakage or the like after the operation of holding the voltage corresponding to the threshold voltage of the driving transistor in the first capacitor has been performed until similar operation is performed next time. In such a case, a video signal voltage that has been corrected to compensate for a change in voltage of the first capacitor may be written to a second capacitor, for example.
[0096] In the present disclosure including the above-described preferable configuration,
[0097] the drive unit applies a reference voltage to the first node, and applies an initialization voltage to the second node and the third node, to set a voltage held by the capacitor unit so as to exceed the threshold voltage of the driving transistor, and subsequently applies the reference voltage to the first node, and applies the driving voltage to one source/drain region of the driving transistor in a state in which the second node and the third node electrically conduct with each other, so as to cause electric potentials of the second node and the third node to get close to a voltage obtained by subtracting the threshold voltage of the driving transistor from the reference voltage, consequently causing a voltage corresponding to the threshold voltage of the driving transistor to be held in the first capacitor.
[0098] In this case, the display elements each further include a second switching transistor, a third switching transistor, and a fourth switching transistor; in the second switching transistor, the reference voltage is applied to one source/drain region, and the other source/drain region is connected to the second node;
in the third switching transistor, one source/drain region is connected to the second node, and the other source/drain region is connected to the third node; in the fourth switching transistor, the reference voltage is applied to one source/drain region, and the other source/drain region is connected to the first node; the reference voltage is applied to the first node by bringing the fourth switching transistor into the conducting state; and the second node and the third node are brought into the conducting state by bringing the third switching transistor into the conducting state. The initialization voltage is supplied from the data line through the first switching transistor. Alternatively, the initialization voltage may be supplied from the electric supply line through the driving transistor.
[0099] The display elements each further include a fifth switching transistor, and the other source/drain region of the driving transistor may be connected to one end of the light-emitting unit through the fifth switching transistor.
[0100] Alternatively, the display elements each further include a second switching transistor, a third switching transistor, and a fourth switching transistor; in the second switching transistor, the initialization voltage is applied to one source/drain region, and the other source/drain region is connected to the second node;
in the third switching transistor, the reference voltage is applied to one source/drain region, and the other source/drain region is connected to the first node; the other source/drain region of the driving transistor is connected to one end of the light-emitting unit through the fourth switching transistor; the reference voltage is applied to the first node by bringing the third switching transistor into the conducting state; the initialization voltage is applied to the first node by bringing the second switching transistor into the conducting state; and a conducting state/a non-conducting state of the second switching transistor are controlled by a control line in common with the first switching transistor.
[0101] In the present disclosure including the above-described preferable configuration,
the drive unit applies a reference voltage to the first node, and applies an initialization voltage to the second node and the third node, to set a voltage held by the capacitor unit so as to exceed the threshold voltage of the driving transistor, and subsequently applies the reference voltage to the first node, and applies the driving voltage to one source/drain region of the driving transistor in a state in which the second node and the third node electrically conduct with each other, so as to cause electric potentials of the second node and the third node to get close to a voltage obtained by subtracting the threshold voltage of the driving transistor from the reference voltage, consequently causing a voltage corresponding to the threshold voltage of the driving transistor to be held in the first capacitor.
[0102] In this case, the display elements each further include a second switching transistor, a third switching transistor, and a fourth switching transistor; in the second switching transistor, the initialization voltage is applied to one source/drain region, and the other source/drain region is connected to the second node;
in the third switching transistor, the reference voltage is applied to one source/drain region, and the other source/drain region is connected to the first node; the other source/drain region of the driving transistor is connected to one end of the light-emitting unit through the fourth switching transistor; the reference voltage is applied to the first node by bringing the third switching transistor into the conducting state; the initialization voltage is applied to the second node by bringing the second switching transistor into the conducting state; and a conducting state/a non-conducting state of the second switching transistor are controlled by a control line in common with the first switching transistor.
[0103] Alternatively, in the present disclosure including the above-described preferable configuration,
the drive unit applies a reference voltage to the second node and the third node, and supplies a driving voltage from the electric supply line in a state in which the first node and one source/drain region of the driving transistor electrically conduct with each other, to set a voltage held by the capacitor unit so as to exceed a threshold voltage of the driving transistor, and subsequently interrupts a connection between the electric supply line and the driving transistor in a state in which the reference voltage is applied to the second node and the third node, so as to cause an electric potential of the first node to get close to an electric potential obtained by adding the threshold voltage of the driving transistor to the reference voltage, consequently causing a voltage corresponding to the threshold voltage of the driving transistor to be held in the first capacitor.
[0104] In this case, the display elements each further include a second switching transistor, a third switching transistor, a fourth switching transistor, and a fifth switching transistor;
in the second switching transistor, the reference voltage is applied to one source/drain region, and the other source/drain region is connected to the second node; in the third switching transistor, one source/drain region is connected to the second node, and the other source/drain region is connected to the third node; a connection between the first node and one source/drain region of the driving transistor is made through the fourth switching transistor; a connection between the electric supply line and one source/drain region of the driving transistor is made through the fifth switching transistor; the reference voltage is applied to the second node and the third node by bringing the second switching transistor and the third switching transistor into the conducting state; the first node and one source/drain region of the driving transistor are brought into the conducting state by bringing the fourth switching transistor into the conducting state; and the connection between the electric supply line and the driving transistor is interrupted by bringing the fifth switching transistor into the non-conducting state.
[0105] In this case, the display elements each further include a sixth switching transistor;* and*
the other source/drain region of the driving transistor is connected to one end of the light-emitting unit through the sixth switching transistor.
[0106] Alternatively, the display elements each further include a second switching transistor, a third switching transistor, and a fourth switching transistor; in the second switching transistor, the reference voltage is applied to one source/drain region, and the other source/drain region is connected to the second node;
a connection between the first node and one source/drain region of the driving transistor is made through the third switching transistor; a connection between the electric supply line and one source/drain region of the driving transistor is made through the fourth switching transistor; the reference voltage is supplied from the data line through the first switching transistor, and is applied to the first node, and the reference voltage is applied to the second node by bringing the second switching transistor into the conducting state; the first node and one source/drain region of the driving transistor are brought into the conducting state by bringing the third switching transistor into the conducting state; and the connection between the electric supply line and the driving transistor is interrupted by bringing the fourth switching transistor into the non-conducting state.
[0107] In the above-described various preferable configurations, a voltage in which the threshold voltage of the driving transistor is reflected suffices as the voltage held in the first capacitor. Therefore, it is not always required that the voltage held in the first capacitor agrees with the threshold voltage.
[0108] In the display device, the display device driving method, the display element, and the electronic apparatus according to the present disclosure including the above-described various preferable configurations (hereinafter, may be merely referred to as “the present disclosure”), the light-emitting unit may include a current-driven electro-optic element, the light emission brightness of which changes according to a value of a flowing current. An organic electroluminescent light-emitting unit, an LED light-emitting unit, a semiconductor laser light-emitting unit, and the like can be mentioned as the current-driven light-emitting unit. These light-emitting units can be configured by using a well-known material or method. From the viewpoint of configuring a flat-type display device, it is preferable that the light-emitting unit includes, above all, an organic electroluminescent light-emitting unit.
[0109] The drive unit used in the present disclosure including the above-described various preferable configurations includes, for example, a circuit such as a data-line drive unit, a power supply unit, and a control-line drive unit. These can be configured by using a well-known circuit element or the like.
[0110] The display device may be a so-called monochrome display configuration, or a color display configuration. In the case of the color display configuration, one pixel may include a plurality of sub-pixels. More specifically, one pixel may include three sub-pixels that are a red light-emitting sub-pixel, a green light-emitting sub-pixel, and a blue light-emitting sub-pixel. Moreover, one pixel may include a set of sub-pixels obtained by further adding one kind of or two or more kinds of sub-pixels to the above three kinds of sub-pixels (for example, a set of sub-pixels obtained by adding a sub-pixel that emits white light for improving brightness, a set of sub-pixels obtained by adding a sub-pixel that emits a complementary color for magnifying a color reproduction range, a set of sub-pixels obtained by adding a sub-pixel that emits yellow for magnifying a color reproduction range, and a set of sub-pixels obtained by adding sub-pixels that emit yellow and cyan for magnifying a color reproduction range).
[0111] As values of pixels (pixels) of the display device, other than VGA (640, 480), S-VGA (800, 600), XGA (1024, 768), APRC (1152, 900), S-XGA (1280, 1024), U-XGA (1600, 1200), HD-TV (1920, 1080), and Q-XGA (2048, 1536), some image display resolutions such as (1920, 1035), (720, 480) and (1280, 960) can be presented. However, image display resolutions are not limited to these values.
[0112] The display element that is included in the display unit is formed in a certain plane (for example, the display element is formed on a support base). For example, through the interlayer insulating layer, the light-emitting unit is formed above the driving circuit that drives the light-emitting unit.
[0113] The driving circuit that drives the light-emitting unit can be configured as a circuit that includes a transistor and a capacitor unit. As the transistor that is included in the driving circuit, for example, a thin film transistor (TFT) can be mentioned. The transistor may be an enhancement type transistor or a depletion type transistor. An n-channel transistor may be formed with a Lightly Doped Drain (LDD) structure. In some cases, the LDD structure may be unsymmetrically formed. For example, a large current flows through the driving transistor when the display element emits light. Therefore, the LDD structure may be formed only in one source/drain region that becomes a drain region at the time of light emission.
[0114] With respect to two source/drain regions of one transistor, there is a case where the term “one source/drain region” is used to mean a source/drain region connected to the power supply side. In addition, when a transistor is in a conducting state, this means a state in which a channel is formed between the source/drain regions. It does not matter whether or not a current flows from one source/drain region of the transistor to the other source/drain region. Meanwhile, when the transistor is in a non-conducting state, this means a state in which a channel is not formed between the source/drain regions. Moreover, the source/drain regions can be configured not only from a conductive material such as polysilicon and amorphous silicon containing impurities, but also from a layer that includes metal, alloy, conductive particles, a layered structure thereof, and an organic material (conductive polymer).
[0115] Each capacitor that is included in the capacitor unit can be configured from a pair of electrodes, and a dielectric layer that is put between these electrodes. The transistor and the capacitor unit that are included in the driving circuit are formed in a certain plane (for example, the transistor and the capacitor unit are formed on the support base). For example, through the interlayer insulating layer, the light-emitting unit is formed above the transistor and the capacitor unit that are included in the driving circuit. It should be noted that a configuration in which a transistor is formed on a semiconductor substrate or the like may be employed.
[0116] Various kinds of wiring lines such as a control line and a data line or an electric supply line are formed on a certain plane (for example, on the support base). These wiring lines can be regarded as a well-known configuration or structure.
[0117] As a constituent material of the support base or a constituent material of a substrate as described later, other than a glass material such as high-strain point glass, soda glass (Na.sub.2O.CaO.SiO.sub.2), borosilicate glass (Na.sub.2O.B.sub.2O.sub.3.SiO.sub.2), forsterite (2MgO.SiO.sub.2), and lead glass (Na.sub.2O.PbO.SiO.sub.2), it is possible to present a flexible polymeric material, for example, a polymeric material, typified by polyether sulfone (PES), polyimide, polycarbonate (PC), and polyethylene terephthalate (PET). It should be noted that a surface of the support base or a surface of the substrate may be provided with various coatings. The constituent material of the support base and the constituent material of the substrate may be the same, or may differ. If the support base and the substrate each including a flexible polymeric material are used, a flexible display device can be configured.
[0118] Conditions represented by various equations in the present description are fulfilled not only in a case where the equations mathematically and strictly hold, but also in a case where the equations substantially hold. With respect to whether or not the equations hold, various dispersions that occur while designing or producing a display element and a display device are allowed.
[0119] In timing charts used in the explanations below, a length (time length) of the horizontal axis indicating each time period is merely schematic, and thus does not indicate a ratio of the time length of each time period. The same applies to the vertical axis. In addition, waveform shapes in the timing chart are also schematic.
First Embodiment
[0120] The first embodiment relates to a display device, a display device driving method, and a display element according to the present disclosure.
[0121] FIG. 1 is a conceptual diagram illustrating a display device according to the first embodiment. A display device 1 is provided with: a display unit 10 in which display elements 11 are arranged; and a drive unit 20 for driving the display unit 10.
[0122] In the display unit 10, the display elements 11 are arranged in a two-dimensional matrix form in a state in which the display elements 11 are connected to first to fifth control lines WS1 to WS5 each extending in a row direction (X direction in FIG. 1), and are connected to data lines DTL each extending in a column direction (Y direction in FIG. 1).
[0123] For convenience of illustration, FIG. 1 shows a connection line relationship for one of the display elements 11, more specifically, for a (n, m)th display element 11 as described later.
[0124] The display device 1 is provided with a data-line drive unit 21, a power supply unit 22, and a control-line drive unit 23. The data-line drive unit 21, the power supply unit 22, and the control-line drive unit 23 constitute the drive unit 20 for driving the display unit 10.
[0125] Various signals are supplied from the control-line drive unit 23 to the first to fifth control lines WS1 to WS5. For example, a video signal voltage corresponding to the brightness of an image to be displayed is supplied to the data lines DTL. A driving voltage or the like is supplied from the power supply unit 22 to electric supply lines DS. Incidentally, there is a case where the first to fifth control lines WS1 to WS5 are merely collectively referred to as “control lines”.
[0126] Although not illustrated in FIG. 1, a region (display region) in which the display unit 10 displays an image is constituted of the display elements 11 that are arranged in a two-dimensional matrix form formed by N pieces in the row direction, and M pieces in the column direction, that is to say, N.times.M pieces in total. The number of rows of the display elements 11 in the display region is M, and the number of the display elements 11 that constitute each row is N.
[0127] The numbers of the first to fifth control lines WS1 to WS5, and the number of the electric supply lines DS, are each M. The display elements 11 in the m-th row (where m=1, 2, … , M) are each connected to the first to fifth control lines WS1.sub.m to WS5.sub.m corresponding to the m-th, and are each connected to the m-th electric supply line DS.sub.m, thereby constituting one display element row. It should be noted that FIG. 1 illustrates only the first to fifth control lines WS1.sub.m to WS5.sub.m, and the electric supply line DS.sub.m.
[0128] In addition, the number of data lines DTL is N. The display elements 11 in the n-th column (where n=1, 2, … , N) are each connected to the n-th data line DTL.sub.n. It should be noted that FIG. 1 illustrates only the data line DTL.sub.n.
[0129] The display element 11 includes: a current-driven light-emitting unit ELP; a capacitor unit CP including a first capacitor C.sub.S1 and a second capacitor C.sub.S2; an n-channel driving transistor TR.sub.Drv that causes a current corresponding to a voltage held by the capacitor unit CP to flow through the light-emitting unit ELP; and a first switching transistor TR.sub.1 that writes a video signal voltage to the capacitor unit CP. The driving transistor TR.sub.Drv includes an n-channel TFT. The same applies to the other transistors.
[0130] In the capacitor unit CP, one end of the first capacitor C.sub.S1 is connected to a gate electrode of the driving transistor TR.sub.Drv to form a first node ND.sub.1_G, the other end of the first capacitor C.sub.S1 is connected to one end of the second capacitor C.sub.S2 to form a second node ND.sub.2, and the other end of the second capacitor C.sub.S2 is connected to one end (anode electrode with which the light-emitting unit is provided) of the light-emitting unit ELP, and to the other source/drain region of the driving transistor TR.sub.Drv to form a third node ND.sub.3_S. In the driving transistor TR.sub.Drv, one source/drain region is connected to the electric supply line DS, and the other source/drain region is connected to the light-emitting unit ELP through a fifth switching transistor TR.sub.5 as described later. In the first switching transistor TIM, one source/drain region is connected to the data line DTL, and the other source/drain region is connected to the third node ND.sub.3_S.
