Patent Application
20230078715
Electroluminescent displays comprise an emissive layer with electroluminescent phosphor material between two layers of conductors. In conventional thin film electroluminescent devices, an alternating or pulsed driving voltage is applied over such emissive layer between a pair of electrodes. Peak-to-peak amplitudes of such driving voltages may be relatively high, resulting in notable charging of the electrodes used to provide such driving voltages.
In conventional devices, each pair of electrodes is discharged after charging by driving both electrodes of the pair to the same electrical potential. Although such method has been proven suitable for use in a variety of circumstances, it may still be desirable to develop new solutions related to electroluminescent displays, for example, to reduce the power consumption and/or increase the brightness of electroluminescent displays.
This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. A display arrangement is provided. The display arrangement comprises a thin film display element with a layer structure extending substantially along a base plane defining a lateral extension of the display element.
The display element comprises a first conductor layer, comprising a common display electrode, and a second conductor layer, comprising a first display electrode and a second display electrode, the common display electrode at least partly laterally overlapping each of the first display electrode and the second display electrode.
The display arrangement further comprises a display driver unit with a primary circuit node configured to be maintained at a first potential, a first display terminal associated with the first display electrode, a second display terminal associated with the second display electrode, and a common display terminal associated with the common display electrode.
Each of the first display terminal and the second display terminal has a first state, wherein said display terminal electrically couples its associated display electrode to the primary circuit node via a primary current path of said display terminal, and a high-impedance state, wherein said primary current path is disconnected. The common display terminal has a first state, wherein the common display electrode is maintained at a second potential and a high-impedance state.
The display driver unit has a rectifying first primary auxiliary current path between the first display electrode and the primary circuit node, and the display driver unit is configured to, while maintaining the second display terminal in its high-impedance state, set the first display terminal and the common display terminal to their first states and, after setting the first display terminal and the common display terminal to their first states, set the second display terminal to its first state, while maintaining the first display terminal and the common display terminal in their high-impedance states, such that electrical current passes between the first display electrode and the second display electrode along a forward direction of the first primary auxiliary current path and via the second display terminal.
The present disclosure will be better understood from the following detailed description read in light of the accompanying drawings, wherein:
Unless specifically stated to the contrary, any drawing of the aforementioned drawings may be not drawn to scale such that any element in said drawing may be drawn with inaccurate proportions with respect to other elements in said drawing in order to emphasize certain structural aspects of the embodiment of said drawing.
Moreover, corresponding elements in the embodiments of any two drawings of the aforementioned drawings may be disproportionate to each other in said two drawings in order to emphasize certain structural aspects of the embodiments of said two drawings.
Concerning display arrangements discussed in this detailed description, the following shall be noted.
Throughout this specification, “potential”, “current”, “impedance” and “charge” may refer to electrical potential, electrical current, electrical impedance, and electrical charge, respectively.
In this disclosure, the terms “primary” and “secondary” may refer to elements related to primary circuit nodes and to secondary circuit nodes, respectively. Further, an ordinal number preceding such term may denote a display terminal related to an element. For example, a “first primary” element may refer to an element related both to a first display terminal and a primary circuit node.
Herein, a “display arrangement” may refer to an arrangement which may form, as such, a complete, operable display. Alternatively, a display arrangement may be used as a part of a complete display comprising also other elements, units, and/or structures. A display arrangement may generally comprise at least one display element.
Throughout this specification, a “display element” may refer to an element comprising at least one emissive area for emitting light therefrom in order to present visual information.
With reference to
Herein, a “thin film” display element may refer to a display element having a total thickness less than or equal to 50 μm, or less than or equal to 20 μm, or less than or equal to 10 μm. Individual layers may have thicknesses, for example, in a range from a few nanometers to some hundreds of nanometers or some micrometers.
The display element 100 of the embodiment of
Herein, a “layer” may refer to a generally sheet-formed element arranged on a surface or a body. Additionally or alternatively, a layer may refer to one of a series of superimposed, overlaid, or stacked generally sheet-formed elements. A layer may generally comprise a plurality of sublayers of different materials or material compositions. A layer may be path-connected. Some layers may be locally path-connected and disconnected.
In this disclosure, a base plane “defining a lateral extension” of an element with a layer structure may refer to said element comprising a layer and having lateral directions along said base plane, in which lateral directions said element may have dimensions substantially larger than in a thickness direction perpendicular to said lateral directions.
In the embodiment of
Throughout this specification, a “conductor” may refer to an electrical conductor material and/or the electrical conductivity thereof. Consequently, a “conductor layer” may refer to a layer comprising a conductor material. Additionally or alternatively, a conductor layer may be electrically non-insulating, e.g., electrically conductive.
A conductor layer may comprise, for example, indium tin oxide (ITO), aluminum-doped zinc oxide (AZO, ZnO:Al), any other appropriate transparent conductive oxide (TCO), and/or any other transparent conductor material. Additionally or alternatively, a conductor layer may comprise metal, for example, a thin metal mesh. Generally, at least one of a first conductor layer and a second conductor layer of a display element may comprise a transparent material and/or structure.
The second conductor layer 120 of the embodiment of
In the embodiment of
Throughout this specification, a “display electrode” may refer to an electrode functionally and/or electrically connectable and/or connected to a display driver unit. Additionally or alternatively, a display electrode may at least partly, i.e., partly or entirely, laterally overlap another display electrode. A display electrode may generally laterally overlap any suitable number, e.g., one, two, three, etc., of other display electrodes. Additionally or alternatively, a display electrode may be suitable for coupling electrical voltage over an emissive layer.
In this specification, an “emissive layer” may refer to layer comprising material capable of emitting light when electrical voltage is coupled over said emissive layer.
Herein, “light” may refer to electromagnetic radiation of any wavelength(s) within a range of relevant wavelengths. The range of relevant wavelengths may overlap or coincide with ultraviolet (wavelength from about 10 nanometers (nm) to about 400 nm), and/or visible (wavelength from about 400 nm to about 700 nm), and/or infrared (wavelength from about 700 nm to about 1 millimeter (mm)) parts of the electromagnetic spectrum.
Further, a “common display electrode” may refer to a display electrode laterally overlapping a plurality of (i.e., at least two, at least three, at least four, etc.) other display electrodes.
In the embodiment of
The first conductor layer 110 of embodiment of
In this specification, a “substrate” may refer to a solid body providing a surface, which may be flat or curved, such that material may be arranged, deposited, etched, and/or inscribed on the surface. A substrate may be formed, for example, of glass, e.g., sodalime, aluminosilicate, and/or any other appropriate glass or plastic. Suitable plastic materials include, for example, polyethylene (PE), polycarbonate (PC), and mixtures thereof, without being limited to these examples.
A substrate may mechanically protect a thin film display element and/or serve as an electrically insulating layer between said thin film display element and surroundings thereof. Further, there may also be another protective and/or insulating layer on an opposite side of said thin film display element. Such another layer may be formed by an external layer or element to which a display element is attached.
In the embodiment of
The first display electrode 121 of the embodiment of
The common display electrode 111 of the embodiment of
Although in
The common display electrode 111 and the first display electrode 121 of the embodiment of
The display element 100 of the embodiment of
Herein, an “inorganic thin film electroluminescent” type of display element may refer to a thin film display element comprising an emissive layer comprising an inorganic phosphor layer. In inorganic TFEL display elements, an emissive layer may further comprise a first insulating layer arranged between an inorganic phosphor layer and a first conductor layer, and a second insulating layer arranged between said phosphor layer and a second conductor layer. In inorganic TFEL displays, an alternating or pulsed driving voltage may be applied over such emissive layer. An inorganic TFEL display driven with pulsed or alternating voltages may be referred to as an inorganic “AC TFEL display”. Peak-to-peak amplitudes of such driving voltages may be, for example, few hundreds of volts, generated by a specific display driver unit and fed to display electrodes via conductors from display terminals of said display driver unit.
It is apparent to a person skilled in the art that a common display electrode may or may not be arranged as an elongated row or column electrode of a matrix-type display element, and one or more of a first display electrode and a second display electrode may or may not be arranged as an elongated column or row electrode, respectively, of said matrix-type display element.
Herein, a “matrix-type display element” may refer to a display element comprising a set of row electrodes and a set of column electrodes directed at an angle in relation to and laterally overlapping one another. Generally, such sets of electrodes may or may not be directed perpendicularly to one another. A TFEL display element organized as a matrix-type display element may be implemented as a passive matrix display element.
In the embodiment of
Herein, a “display driver unit” may refer to a display-powering means suitable for and/or configured to supply electrical power to a display element of a display arrangement to bring about emission of light.
A display driver unit may or may not form a part of a multifunctional control system. In some embodiments, a display driver unit may be implemented as a separate unit, whereas in others a display driver unit may be implemented as a sub-unit of a control system further comprising other suitable sub-units.
A display driver unit being “configured to” perform a process may refer to capability of and suitability of said display driver unit for such process. This may be achieved in various ways. For example, a display driver unit may comprise at least one processor and at least one memory coupled to the at least one processor, the memory storing program code instructions which, when executed on said at least one processor, cause the processor to perform the process(es) at issue.
Additionally or alternatively, any functionally described features of a display driver unit may be performed, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of suitable hardware logic components include Field-programmable Gate Arrays (FPGAs), Application-specific Integrated Circuits (ASICs), Application-specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), etc. A display driver unit may generally be operated in accordance with any appropriate principles and by means of any appropriate circuitry and signals known in the art for powering display elements of display arrangements.
In the embodiment of
In the embodiment of
In the embodiment of
Owing to its physical nature, the emissive layer 130 may emit light in a pulsed manner. When light pulses are repeatedly brought about by a plurality of voltage pulses in rapid succession, such light pulses may be perceived as a constant source of light, owing to the persistence of vision, also referred to as flicker fusion.
In the embodiment of
In the embodiment of
Herein, “terminal” may refer to an interface of a device whereto external elements, such as electrodes and/or electrical circuits, may be connected. The term “terminal” may also refer to any electronic components configured to modify electrical signals transmitted and/or received via said terminal.
Further, a “display terminal” may refer to a terminal of a display driver unit suitable for providing power to a display electrode in a display arrangement.
Each of the first display terminal 221 and the second display terminal 222 of the embodiment of
Throughout this disclosure, a “current path” may refer to an electrical connection between two elements, enabling a continuous flow of direct (i.e., unidirectional) electrical current between said elements.
Each of the first display terminal 221 and the second display terminal 222 of the embodiment of
Additionally, each of the first display terminal 221 and the second display terminal 222 of the embodiment of
In the high-impedance state of the first display terminal 221, the first secondary current path 312 is disconnected. Correspondingly, in the high-impedance state of the second display terminal 222, the second secondary current path 322 is disconnected. In other embodiments, wherein a display terminal has a second state, wherein said display terminal couples its associated display electrode to a secondary circuit node via its secondary current path, said secondary current path may be disconnected in a high-impedance state of said display terminal.
The common display terminal 211 of the embodiment of
In its first state, the common display terminal 211 may electrically couple the common display electrode 111 to the secondary circuit node 202. In other embodiments, a common display terminal may or may not electrically couple a common display electrode to a secondary circuit node in its first state.
The common display terminal 211 of the embodiment of
In its second state, the common display terminal 211 may electrically couple the common display electrode 111 to the primary circuit node 201. In other embodiments, a common display terminal may or may not electrically couple a common display electrode to a primary circuit node in its second state.
With reference to
Each of the first display terminal 221, the second display terminal 222, and the common display terminal 211 is configured to receive an enable signal EN1, EN2, ENCOM, determining whether said terminal is to be maintained in its high-impedance state. If an enable signal corresponding to maintaining a high-impedance state (for example, logical 0) is received by one of the terminals, said terminal is maintained in its high-impedance state, irrespective of other signals received by said terminal. Nevertheless, if an enable signal corresponding to maintaining an enabled state (for example, logical 1) is received by one of the terminals, said terminal is set to some enabled state, for example, a first state or a second state, based on the contents of a channel signal CH1, CH2, CHCOM last received by said terminal.
As depicted in
Herein, a “rectifying current path” may refer to a current path exhibiting asymmetric electrical conductance. A rectifying current path may generally exhibit a first electrical resistance for current passing along its primary conduction direction, i.e., its forward direction, and a second electrical resistance considerably higher than the first electrical resistance for current passing opposite its forward direction, i.e., along its reverse direction. A rectifying current path may be provided, for example, between the pins of a semiconductor diode.
In the embodiment of
Additionally, the display driver unit 200 of the embodiment
In embodiments, wherein a common display electrode of a first conductor layer of a display element of a display arrangement laterally overlaps each of a plurality of display electrodes of a second conductor layer of said display element at a separate overlapping region, a “partial sequence” of a driving sequence of said display arrangement may refer to a series of stages during which emission of light is brought about at least once, e.g., once, at each of said overlapping regions.
In general, a driving sequence of the display arrangement may comprise a series of stages similar or different to the stages of the driving sequence of the embodiment of
With reference to
Consequently, light is emitted by the first emissive part 131, as depicted by wavy arrows in
Throughout this specification, an element or material being “transparent”, may refer to a quality, i.e., “transparency”, of said element or material of allowing light of wavelength(s) within a range of relevant wavelengths to propagate through such element or material. Said range of relevant wavelengths may generally depend on intended usage of such transparent element or material.
Additionally, in the embodiment of
As depicted in
With reference to
Since the first primary auxiliary current path 411 and the second display terminal 222 of the embodiment of
In other embodiments, a display driver unit may generally be configured to, after setting a first display terminal and a common display terminal to their first states, set a second display terminal to its first state, while maintaining said first display terminal and said common display terminal in their high-impedance states, such that electrical current passes between said first display electrode and said second display electrode along a forward direction of a first primary auxiliary current path and via a second display terminal. A display driver unit of a display arrangement being configured in such manner may generally reduce power consumption of said display driver unit and/or increase a brightness of a display element of said display arrangement.
With reference to
Light emitted by the second emissive part 132 passes through the second display electrode 122. As such, the second display electrode 122 is transparent. In other embodiments, at least one of a second display electrode and a common display electrode may be transparent.
As depicted in
With reference to
Generally, a display driver unit may be configured to set a common display terminal to its second state to at least partly discharge a first display electrode and a second display electrode, while maintaining a first display terminal in its first state or its high-impedance state and while maintaining a second display terminal in its first state or its high-impedance state.
Throughout this specification, “discharging” may refer to reduction or removal of net electrical charge from an electrode.
In the embodiment of
The discharging of both the first display electrode 121 and the second display electrode 122 concludes the first partial sequence of the driving sequence of the display arrangement 1, during which emission of light is achieved by coupling the second potential V2 to the first conductor layer 110 and the first potential V1 to the second conductor layer 120. In the following, stages included in the second partial sequence are described.
With reference to
As depicted in
With reference to
With reference to
As depicted in
Finally, referring back to
Such discharging of both the first display electrode 121 and the second display electrode 122 concludes the second partial sequence of the driving sequence of the display arrangement 1, during which emission of light is achieved by coupling the first potential V1 to the first conductor layer 110 and the second potential V2 to the second conductor layer 120.
Evidently, in the embodiment of
In the embodiment of
Although a first display terminal 221 is depicted in
The first display terminal 221 of the embodiment of
In the embodiment of
Herein, a “push-pull output stage” may refer to an electronic circuit, wherein a complementary pair of transistors is used to supply current to a load from a positive voltage source and to absorb current from a load to ground or a negative voltage supply.
The push-pull output stage 500 of the embodiment of
The first transistor 510 has its source connected to a primary circuit node 201, configured to be maintained at a first potential V1, and its drain connected to the first display electrode 121. On the other hand, the second transistor 520 has its source connected to a secondary circuit node 202, configured to be maintained at a second potential V2, and its drain connected to the first display electrode 121. In other embodiments, any suitable electrical connections may be utilized for a first transistor and a second transistor.
In the embodiment of
In the embodiment of
Herein, a “body diode structure” may refer to a semiconductor diode structure between a drain and a source of a MOSFET. Body diode structures may be commonly utilized in so-called power MOSFETs, i.e., MOSFETs designed to handle high power levels.
It is to be understood that the embodiments described above may be used in combination with each other. Several of the embodiments may be combined together to form a further embodiment.
It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The invention and its embodiments are thus not limited to the examples described above, instead they may vary within the scope of the claims.
It will be understood that any benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages.
The term “comprising” is used in this specification to mean including the feature(s) or act(s) followed thereafter, without excluding the presence of one or more additional features or acts. It will further be understood that reference to ‘an’ item refers to one or more of those items.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20205175 | Feb 2020 | FI | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FI2021/050125 | 2/19/2021 | WO |
