Display device

Abstract

This display device comprises: a first light-emitting layer that emits light in a first direction in which a display surface is oriented; a light accumulation layer that is provided on the second direction side of the first light-emitting layer and accumulates light received from the first direction side, the second direction being opposite to the first direction; and a second light-emitting layer that is provided between the first light-emitting layer and the light accumulation layer and emits light toward the light accumulation layer. The power consumption of the second light-emitting layer is lower than the power consumption of the first light-emitting layer. The light accumulation layer accumulates at least light from the second light-emitting layer and emits the same in the first direction.

Description

Display device

[0001] The present invention relates to a display device.

[0002] In organic EL displays, which are a type of display device, images and the like are displayed by the self-emission of light-emitting elements composed of OLEDs (organic light-emitting diodes). In liquid crystal display devices, images and the like are displayed by a backlight composed of light-emitting elements provided on the back surface of a liquid crystal layer, which illuminates the liquid crystal layer. Liquid crystal display devices that are provided with a phosphorescent layer to supplement the light emission of the backlight are also known (see, for example, Patent Document 1).

[0003] JP 2009-115921 A

[0004] In self-luminous and liquid crystal display devices, in environments with high illuminance from external light such as sunlight or lighting, the visibility of the display may be deteriorated if the brightness of the light emitted by the light-emitting elements is insufficient. Also, in such display devices, power is constantly consumed by the light-emitting elements in low-illuminance environments.

[0005] The present invention has been made in view of the above problems, and has an object to provide a display device that can improve visibility and reduce power consumption in accordance with the illuminance of external light.

[0006] In order to solve the above problem, a display device according to one aspect of the present disclosure includes a first light-emitting layer that emits light in a first direction that is a direction in which a display surface is faced, a light-storing layer that is provided on a second direction side of the first light-emitting layer and stores light received from the first direction side, the second direction being the opposite direction to the first direction, and a second light-emitting layer that is provided between the first light-emitting layer and the light-storing layer and emits light toward the light-storing layer, wherein the power consumption of the second light-emitting layer is lower than the power consumption of the first light-emitting layer, and the light-storing layer stores light from at least the second light-emitting layer and emits light in the first direction.

[0007] According to the above aspect, the luminous layer emits light in the first direction based on the energy of the received light, thereby making it possible to supplement the luminance for display, thereby improving the visibility of the display when the illuminance of external light is high. Furthermore, when the illuminance is low, the display is realized by the luminescence of the luminous layer based on the storage of light from the second light-emitting layer, so it is possible, for example, to reduce the amount of light emitted by the first light-emitting layer or to make the first light-emitting layer non-emitting, thereby making it possible to reduce power consumption.

[0008] It is possible to provide a display device that can improve visibility and reduce power consumption in accordance with the illuminance of external light.

[0009] It is a figure which shows typically an example of the configuration of the display device of this embodiment. It is a figure which shows typically the configuration of the control part which controls the light emission of the first and second light-emitting layers. It is a flowchart which shows the control process of the light emission by the control part. It is a figure which shows typically the configuration of another example of the display device of this embodiment.

[0010] An embodiment of a display device according to the present invention will be described with reference to the drawings. Whenever possible, the same parts are designated by the same reference numerals and redundant description will be omitted.

[0011] The display device of this embodiment is, for example, a self-luminous organic EL display, a liquid crystal display device, etc. A self-luminous organic EL display displays images and the like by using elements such as OLEDs that emit light. A liquid crystal display device displays images and the like by using a backlight provided on the back surface of the liquid crystal layer and configured with light-emitting elements to illuminate the liquid crystal layer.

[0012] 1 is a diagram schematically illustrating an example of the configuration of a display device according to this embodiment. The display device 1 shown in Fig. 1 is a self-luminous display device such as an organic EL display.

[0013] The display device 1 includes a first light-emitting layer 11, a phosphorescent layer 12, and a second light-emitting layer 13. The display device 1 also includes a glass substrate 14, a transparent electrode 15, a TFT layer 16, a color filter 17, a TFT layer 18, and a glass substrate 19.

[0014] The first light-emitting layer 11 is a layer that emits light (11l) in a first direction d1, which is the direction in which the display surface ds is facing. The first light-emitting layer 11 illustrated in FIG. 1 is a self-emitting element constituted by, for example, an OLED. In the first light-emitting layer 11, when a voltage is applied between the electrodes sandwiching the light-emitting layer, electrons and holes are injected from the cathode and anode, respectively, to form electron-hole pairs. The electrons and holes combine in the light-emitting layer to reach a high-energy state (excited state). When they return from the high-energy state to their original stable energy state (ground state), the difference in energy is released as light, thereby realizing light emission 11l in the first light-emitting layer 11.

[0015] The first light-emitting layer 11 is pixel-controlled by the TFT layer 16. The color of light emitted by each pixel in the first light-emitting layer 11 (for example, any one of R, G, and B) is determined by the molecular structure of the semiconductor used.

[0016] The luminous layer 12 is provided on the second direction d2 side of the first light-emitting layer 11 and is a layer that stores light received from the first direction d1 (stores light energy). The second direction d2 is the opposite direction to the first direction d1. The luminous layer 12 emits light (12l) in the first direction d1 based on the stored energy. Note that, for convenience of illustration, the first direction d1 and the second direction d2 extend perpendicular to the display surface ds in FIG. 1, but the first direction d1 as the direction of light emission 12l and the second direction d2, which is the opposite direction, are not limited to being perpendicular to the display surface ds.

[0017] The luminous layer 12 stores external light L incident on the display surface ds. The luminous layer 12 also stores light emitted by the second light-emitting layer 13 (described later) through light emission 13l. The luminous layer 12 can be made of a known material with luminous properties, but as an example, it may be made of a long-lasting phosphor made by mixing a trace amount of a rare earth element into a strontium compound. The luminous layer 12 becomes excited by absorbing light energy and emits light when it returns from the excited state to the ground state.

[0018] The second light-emitting layer 13 is provided between the first light-emitting layer 11 and the phosphorescent layer 12, and emits light (13l) toward the phosphorescent layer 12. The second light-emitting layer 13 is composed of a self-emitting element, similar to the first light-emitting layer 11, and is composed of, for example, a light-emitting diode. That is, the second light-emitting layer 13 is excited when a voltage is applied between the electrodes sandwiching the light-emitting layer, and the difference in energy when returning from the excited state to the ground state is released as light, thereby realizing light emission 13l. The second light-emitting layer 13 is pixel-controlled by the TFT layer 18 in the same way as the first light-emitting layer 11.

[0019] The color of light emitted from the second light-emitting layer 13 is not limited, and the second light-emitting layer 13 may be formed of, for example, a white light-emitting diode. The power consumption of the second light-emitting layer 13 is configured to be lower than the power consumption of the first light-emitting layer 11.

[0020] The glass substrate 14 is a substrate made of transparent glass having a smooth surface, and forms the display surface ds of the display device 1 .

[0021] The transparent electrode 15 is an electrode made of a material that is transparent like glass and conductive like metal, and applies a voltage to the first light-emitting layer 11 .

[0022] The TFT layer 16 is a layer in which TFTs (Thin Film Transistors) are formed. The TFTs in the layer control the brightness of the light-emitting elements of the first light-emitting layer 11 for each pixel.

[0023] The color filter 17 is a filter that imparts color information such as RGB to the light emitted by the luminous layer 12. This controls the color that appears on the display surface ds due to the light emission 12l from the luminous layer 12 to be the same for each pixel as the color that appears on the display surface ds due to the light emission 11l from the first light-emitting layer 11.

[0024] The TFT layer 18 is a layer in which TFTs are formed. The TFTs in the layer control the brightness of the light-emitting element of the second light-emitting layer 13 for each pixel.

[0025] The glass substrate 19 is a substrate made of transparent glass having a smooth surface, and forms the substrate of the display device 1 .

[0026] The display device 1 of this embodiment further includes an illuminance sensor SE and a control unit 20. Fig. 2 is a diagram schematically illustrating the configuration of the control unit that controls the light emission of the first and second light-emitting layers. The illuminance sensor SE acquires illuminance that represents the brightness of light illuminating the display surface ds of the display device 1. The illuminance sensor SE may be a sensor that detects the illuminance of the environment surrounding the display device 1.

[0027] The control unit 20 controls the light emission of the first light-emitting layer 11 and the second light-emitting layer 13 according to the illuminance state acquired by the illuminance sensor SE. Specifically, the control unit 20 controls the switch state ss according to the illuminance, thereby supplying power from the power source ES to the first light-emitting layer 11 and the second light-emitting layer 13 and controlling the light emission of the first light-emitting layer 11 and the second light-emitting layer 13. The control unit 20 may be realized by a dedicated circuit, or may be realized by a processor that executes a program for realizing the functions of the control unit 20.

[0028] 3 is a flowchart showing the light emission control process by the control unit 20. In a first case where the illuminance exceeds a given threshold or is equal to or greater than the threshold, the control unit 20 controls the first light-emitting layer 11 to emit light and the second light-emitting layer 13 not to emit light, and in a second case where the illuminance is equal to or less than the threshold, the control unit 20 controls the first light-emitting layer 11 not to emit light and controls the phosphorescent layer 12 to emit light.

[0029] 2 and 3, the control process of the control unit 20 to control the light emission of the light-emitting layers 11 and 13 will be described. In step S1, the control unit 20 acquires the illuminance of the environment surrounding the display device 1, which is detected by the illuminance sensor SE.

[0030] In step S11, the control unit 20 determines whether the first case is true, in which the illuminance is equal to or greater than the threshold value. If it is determined that the first case is true, the process proceeds to step S12. On the other hand, if it is not determined that the first case is true, that is, if it is determined that the second case is true, in which the illuminance is less than the threshold value or equal to or less than the threshold value, the process proceeds to step S21. Note that the threshold value for illuminance may be, for example, 200 lx, but the threshold is not limited to this value.

[0031] In step S12, the control unit 20 controls the switch state ss to (2'b00). In step S13, the control unit 20 controls the switch state ss to cause the first light-emitting layer 11 to emit light and to cause the second light-emitting layer 13 not to emit light. At this time (first case), the phosphorescent layer 12 stores external light L illuminating the display surface ds and emits light in the first direction d1.

[0032] As a result, the light emission 11l from the first light-emitting layer 11 realizes the display of an image or the like on the display surface ds, and the light emission 12l from the phosphorescent layer 12 functions as a backlight to compensate for the amount of light. Therefore, in a high-illuminance environment, if the light emission in the direction in which the display surface ds is facing is insufficient, the visibility of the display will decrease, but the light emission 12l from the phosphorescent layer 12 compensates for the amount of light, so the decrease in visibility is prevented.

[0033] If it is determined in step S11 that the illuminance corresponds to the second case, the process proceeds to step S21. In step S21, the control unit 20 determines whether the switch state ss is (2'b00). If it is determined that the switch state ss is (2'b00), the process proceeds to step S22. On the other hand, if it is not determined that the switch state ss is (2'b00), the process proceeds to step S31.

[0034] In step S22, the control unit 20 controls the switch state ss to (2'b01). In step S23, the control unit 20 controls the switch state ss so that the first light-emitting layer 11 does not emit light and the second light-emitting layer 13 emits light. At this time (second case), the luminous layer 12 stores low-illuminance external light L and also stores light emitted 13l from the second light-emitting layer 13. The luminous layer 12 then emits light in the first direction d1 based on the energy of the stored light.

[0035] In this way, in the second case where the illuminance is low, the display of an image or the like on the display surface ds is realized by the light emission 12l of the phosphorescent layer 12 based on the storage of light emitted 13l from the second light-emitting layer 13, which consumes less power than the first light-emitting layer 11, and therefore it is possible to reduce power consumption by making the first light-emitting layer 11 non-emitting.

[0036] In step S24, the control unit 20 causes the second light-emitting layer 13 to emit light for a certain period of time, thereby storing light in the phosphorescent layer 12. This certain period of time may be set to any time without any limitations, and may be, for example, 30 seconds.

[0037] In step S25, when a certain time (given light-emitting time) has elapsed since the second light-emitting layer 13 was caused to emit light, the control unit 20 controls the switch state ss to (2'b1x), and in step S26, stops the light emission of the second light-emitting layer 13.

[0038] In this way, the light emission 13l of the second light-emitting layer 13 is stopped after a given light-emitting time has elapsed, and the light emission 12l in the phosphorescent layer 12 continues based on the energy already absorbed, thereby making it possible to further reduce power consumption.

[0039] If it is determined in step S21 that the switch state ss is not (2'b00), the process proceeds to step S31. In step S31, the control unit 20 determines whether the amount of light emitted 12l from the phosphorescent layer 12 is sufficient. Specifically, the control unit 20 may acquire information indicating whether the amount of light emitted 12l from the phosphorescent layer 12 is sufficient based on an input operation on the display device 1 from a user viewing the display surface ds. The control unit 20 may also acquire information from an optical sensor (not shown) provided on the display device 1 that can detect the amount of light emitted 12l from the phosphorescent layer 12 as information indicating whether the amount of light emitted 12l from the phosphorescent layer 12 is sufficient. If it is determined that the amount of light emitted 12l from the phosphorescent layer 12 is sufficient, the process proceeds to step S32. On the other hand, if it is not determined that the amount of light emitted 12l from the phosphorescent layer 12 is sufficient, the process proceeds to step S41.

[0040] In step S32, the control unit 20 controls the switch state ss to (2'b01). In step S33, the control unit 20 controls the switch state ss so that the first light-emitting layer 11 emits light and the second light-emitting layer 13 does not emit light. In this way, when the amount of light emitted 12l from the phosphorescent layer 12 is sufficient, the light emission 13l of the second light-emitting layer 13 is stopped, and the light emission 12l in the phosphorescent layer 12 continues based on the energy that has already been absorbed, making it possible to further reduce power consumption.

[0041] If it is not determined in step S31 that the amount of light emitted 12l from the luminescent layer 12 is sufficient, the process proceeds to step S41. In step S41, the control unit 20 controls the switch state ss to (2'b01). In step S42, the control unit 20 controls the switch state ss to prevent the first light-emitting layer 11 from emitting light and to cause the second light-emitting layer 13 to emit light. At this time (second case), the luminescent layer 12 stores low-illuminance external light L and also stores light emitted 13l from the second light-emitting layer 13. The luminescent layer 12 then emits light in the first direction d1 based on the energy of the stored light.

[0042] In this way, in the second case where the illuminance is low, the display of an image or the like on the display surface ds is realized by the light emission 12l of the phosphorescent layer 12 based on the storage of light emitted 13l from the second light-emitting layer 13, which consumes less power than the first light-emitting layer 11, and therefore it is possible to reduce power consumption by making the first light-emitting layer 11 non-emitting.

[0043] In step S43, the control unit 20 causes the second light-emitting layer 13 to emit light for a certain period of time, thereby storing light in the phosphorescent layer 12. This certain period of time may be set to any time without any limitations, and may be, for example, 30 seconds.

[0044] In step S44, when a certain time (given light-emitting time) has elapsed since the second light-emitting layer 13 was caused to emit light, the control unit 20 controls the switch state ss to (2'b1x), and in step S45, stops the light emission of the second light-emitting layer 13. In this way, the light emission 13l of the second light-emitting layer 13 is stopped after the given light-emitting time has elapsed, and the light emission 12l of the phosphorescent layer 12 continues based on the energy that has already been absorbed, so that further reduction in power consumption is possible.

[0045] Fig. 4 is a diagram schematically illustrating the configuration of another example of a display device according to this embodiment. The display device 1A (1) shown in Fig. 4 is a liquid crystal display device. In the display device 1A, a backlight composed of light-emitting elements provided on the back surface of the liquid crystal layer illuminates the liquid crystal layer, thereby displaying images and the like.

[0046] The display device 1A includes a first light-emitting layer 11A (11), a phosphorescent layer 12A (12), and a second light-emitting layer 13A (13). The display device 1A also includes a glass substrate 31, a color filter 32, a transparent electrode 33, a liquid crystal layer 34, and a glass substrate 35.

[0047] The first light-emitting layer 11A is a layer that emits light (11al) in a first direction d1, which is the direction in which the display surface ds is facing, and is a so-called backlight. The first light-emitting layer 11A is composed of a light-emitting element such as a light-emitting diode. The color of light emitted by the first light-emitting layer 11A is not limited, and the first light-emitting layer 11A may be composed of, for example, a white light-emitting diode.

[0048] The luminous layer 12A is provided on the second direction d2 side of the first light-emitting layer 11A and is a layer that stores light received from the first direction d1 (stores light energy). The second direction d2 is the opposite direction to the first direction d1. The luminous layer 12A emits light (12al) in the first direction d1 based on the stored energy. Note that, for convenience of illustration, the first direction d1 and the second direction d2 extend perpendicular to the display surface ds in FIG. 1, but the first direction d1 as the direction of light emission 12al and the second direction d2, which is the opposite direction, are not limited to being perpendicular to the display surface ds.

[0049] The luminous layer 12A stores external light L incident on the display surface ds. The luminous layer 12 also stores light emitted by a second light-emitting layer 13A (described later) through an emission 13al. The luminous layer 12A, like the luminous layer 12, can be made of a material having known luminous properties.

[0050] The second light-emitting layer 13A is provided between the first light-emitting layer 11A and the phosphorescent layer 12A, and emits light (13a1) toward the phosphorescent layer 12A. The second light-emitting layer 13A is composed of a self-luminous element, similar to the first light-emitting layer 11A, and is composed of, for example, a light-emitting diode. The color of light emitted by the second light-emitting layer 13A is not limited, and the second light-emitting layer 13A may be composed of, for example, a white light-emitting diode. The power consumption of the second light-emitting layer 13A is configured to be lower than the power consumption of the first light-emitting layer 11A.

[0051] The glass substrate 31 is a substrate made of transparent glass having a smooth surface, and forms the display surface ds of the display device 1A.

[0052] The color filter 32 is a filter that provides color information such as RGB to light 11al emitted by the first light-emitting layer 11A that constitutes the backlight and that passes through the liquid crystal layer 34, and to light 12al emitted by the phosphorescent layer 12A and that passes through the liquid crystal layer 34.

[0053] The transparent electrode 33 is an electrode made of a material that is transparent like glass and that conducts electricity like metal, and applies a voltage to the liquid crystal layer 34 .

[0054] The liquid crystal layer 34 is a layer that controls the amount of light traveling in the first direction d1 by changing the orientation of the liquid crystal molecules in response to the voltage applied by the electrodes.

[0055] The glass substrate 35 is a substrate made of transparent glass having a smooth surface, and forms the substrate of the display device 1A.

[0056] 1, the display device 1A includes an illuminance sensor SE and a control unit 20. Similar to the control unit of the display device 1 described with reference to FIGS. 2 and 3, the control unit 20 of the display device 1A controls the light emission of the first light-emitting layer 11A and the second light-emitting layer 13A in accordance with the illuminance, and also controls the light storage and light emission of the phosphorescent layer 12A. In this way, even in the display device 1A configured as a liquid crystal display device having a backlight, it is possible to improve visibility and reduce power consumption.

[0057] According to the display devices 1, 1A of the present embodiment described above, the luminous layers 12, 12A emit light in the first direction d1 based on the energy of the received light, thereby making it possible to supplement the luminance for display, thereby improving the visibility of the display when the illuminance of the external light L is high. Furthermore, when the illuminance is low, the display is realized by the emission of light from the luminous layers 12, 12A based on the storage of light from the second light-emitting layers 13, 13A, so it becomes possible, for example, to reduce the amount of light emitted by the first light-emitting layers 11, 11A or to make the first light-emitting layers 11, 11A non-emitting, thereby making it possible to reduce power consumption.

[0058] A display device according to the present disclosure may have the following configurations: The actions and effects of each configuration are described below.

[0059] A display device according to one aspect of the present disclosure comprises a first light-emitting layer that emits light in a first direction that is the direction in which a display surface is faced; a luminescent layer that is provided on a second direction side of the first light-emitting layer and stores light received from the first direction side, the second direction being the opposite direction to the first direction; and a second light-emitting layer that is provided between the first light-emitting layer and the luminescent layer and emits light toward the luminescent layer, wherein the power consumption of the second light-emitting layer is lower than the power consumption of the first light-emitting layer, and the luminescent layer stores light from at least the second light-emitting layer and emits light in the first direction.

[0060] According to the above aspect, the luminous layer emits light in the first direction based on the energy of the received light, thereby making it possible to supplement the luminance for display, thereby improving the visibility of the display when the illuminance of external light is high. Furthermore, when the illuminance is low, the display is realized by the luminescence of the luminous layer based on the storage of light from the second light-emitting layer, so it is possible, for example, to reduce the amount of light emitted by the first light-emitting layer or to make the first light-emitting layer non-emitting, thereby making it possible to reduce power consumption.

[0061] Furthermore, a display device according to another aspect may further include an illuminance sensor that acquires an illuminance representing the brightness of light illuminating a display surface of the display device, and a control unit that controls the first light-emitting layer to emit light and the second light-emitting layer not to emit light in a first case where the illuminance exceeds a given threshold or is equal to or greater than the threshold, and that controls the first light-emitting layer not to emit light and causes the phosphorescent layer to emit light in a second case where the illuminance is equal to or less than the threshold.

[0062] According to the above aspects, in the first case, the display is realized by the light emission from the first light-emitting layer and the light emission from the phosphorescent layer based on the storage of external light, so that good visibility of the display is maintained even under high illuminance. In the second case, the display is realized by the light emission from the phosphorescent layer without causing the first light-emitting layer to emit light, so that power consumption can be reduced.

[0063] In addition, in the display device according to another aspect, in the second case, the control unit may cause the second light-emitting layer to emit light, thereby causing the phosphorescent layer to store and emit light.

[0064] According to the above aspect, the light storage and light emission in the phosphorescent layer are realized by the light emission of the second light-emitting layer, which consumes less power than the first light-emitting layer, so that it is possible to reduce the power consumption in displaying the display device.

[0065] In a display device according to another aspect, the control unit may cause the second light-emitting layer to emit light when the amount of light emitted from the phosphorescent layer is less than a predetermined level.

[0066] According to the above aspect, when the amount of light emitted from the luminescent layer is equal to or greater than a predetermined level, the second luminescent layer is not caused to emit light, so that the luminescence in the luminescent layer continues based on the energy already absorbed, thereby enabling a reduction in power consumption.

[0067] In addition, in a display device according to another aspect, the control unit may stop the second light-emitting layer from emitting light when a given light-emitting time has elapsed since the second light-emitting layer was made to emit light.

[0068] According to the above aspect, the emission of light from the second light-emitting layer is stopped after the emission time has elapsed, and the emission of light from the phosphorescent layer continues based on the energy already absorbed, thereby enabling further reduction in power consumption.

[0069] In a display device according to another aspect, in the first case, the phosphorescent layer may store external light that illuminates the display surface and emit light in a first direction.

[0070] According to the above aspect, in a high-illuminance environment, if the light emitted in the direction in which the display surface is facing is insufficient, the visibility of the display will decrease. However, the light emitted from the phosphorescent layer compensates for the amount of light, thereby preventing the decrease in visibility.

[0071] In a display device according to another aspect, the display device may be a self-luminous display device, and the first light-emitting layer may include elements that emit light in a plurality of different colors.

[0072] According to the above aspect, for example, in a self-luminous organic EL display constituted by OLEDs, it is possible to improve visibility and reduce power consumption.

[0073] In a display device according to another aspect, the display device may be a liquid crystal display device, and the first light-emitting layer may be a backlight for a liquid crystal included in the liquid crystal display device.

[0074] According to the above aspect, in a liquid crystal display device having a backlight, it is possible to improve visibility and reduce power consumption.

[0075] Although the present embodiment has been described in detail above, it is clear to those skilled in the art that the present embodiment is not limited to the embodiment described in this specification. The present embodiment can be implemented in modified and altered forms without departing from the spirit and scope of the present invention as defined by the claims. Therefore, the description in this specification is intended to be illustrative and does not have any limiting meaning on the present embodiment.

[0076] As used in this disclosure, the terms "determining" and "determining" may encompass a wide variety of actions. "Determining" and "determining" may include, for example, judging, calculating, computing, processing, deriving, investigating, looking up, searching, inquiring (e.g., searching in a table, database, or other data structure), ascertaining, and the like. "Determining" and "determining" may also include receiving (e.g., receiving information), transmitting (e.g., sending information), input, output, accessing (e.g., accessing data in memory), and the like. Furthermore, "judgment" and "decision" can include regarding resolving, selecting, choosing, establishing, comparing, etc. as having been "judged" or "decided." In other words, "judgment" and "decision" can include regarding some action as having been "judged" or "decided." Furthermore, "judgment (decision)" can be interpreted as "assuming," "expecting," "considering," etc.

[0077] As used in this disclosure, the phrase "based on" does not mean "based only on," unless expressly specified otherwise. In other words, the phrase "based on" means both "based only on" and "based at least on."

[0078] When designations such as "first," "second," etc. are used in this disclosure, any reference to an element does not generally limit the quantity or order of those elements. These designations may be used herein as a convenient method of distinguishing between two or more elements. Thus, a reference to a first and a second element does not imply that only two elements may be employed therein or that the first element must precede the second element in some way.

[0079] To the extent that the terms "include," "including," and variations thereof are used herein or in the claims, these terms are intended to be inclusive, similar to the term "comprising." Furthermore, the term "or," as used herein or in the claims, is not intended to be an exclusive or.

[0080] In this disclosure, where articles are added by translation, such as a, an, and the in English, the disclosure may include that the nouns following these articles are in the plural form.

[0081] Throughout this disclosure, the plural is intended to be included unless the singular is clearly indicated by the context.

[0082] The display device of the present disclosure may have the following configuration: [1] A display device including: a first light-emitting layer that emits light in a first direction that is a direction toward which a display surface is directed; a light-storing layer that is provided on a second direction side of the first light-emitting layer and that stores light received from the first direction side, the second direction being opposite to the first direction; and a second light-emitting layer that is provided between the first light-emitting layer and the light-storing layer and that emits light toward the light-storing layer, wherein power consumption of the second light-emitting layer is lower than power consumption of the first light-emitting layer, and the light-storing layer stores light from at least the second light-emitting layer and emits light in the first direction. [2] The display device according to [1], further comprising: an illuminance sensor that acquires an illuminance representing the brightness of light illuminating a display surface of the display device; and a control unit that controls the first light-emitting layer to emit light and the second light-emitting layer not to emit light in a first case where the illuminance exceeds a given threshold or is equal to or greater than the threshold, and controls the first light-emitting layer not to emit light and the phosphorescent layer to emit light in a second case where the illuminance is equal to or less than the threshold. [3] The display device according to [2], in which the control unit controls the second light-emitting layer to emit light in the second case, causing the phosphorescent layer to store and emit light. [4] The display device according to [3], in which the control unit controls the second light-emitting layer to emit light when an amount of light emitted from the phosphorescent layer is less than a predetermined level. [5] The display device according to [3] or [4], in which the control unit controls the second light-emitting layer to emit light when a given light-emitting time has elapsed since the second light-emitting layer was caused to emit light. [6] The display device according to any one of [2] to [5], wherein in the first case, the luminous layer stores luminescence from external light illuminating the display surface and emits light in the first direction. [7] The display device according to any one of [1] to [6], wherein the display device is a self-luminous display device, and the first luminous layer includes elements that emit light in a plurality of different luminous colors.[8] The display device according to any one of [1] to [6], wherein the display device is a liquid crystal display device, and the first light-emitting layer is a backlight for a liquid crystal included in the liquid crystal display device.

[0083] 1, 1A...display device, 11, 11A...first light-emitting layer, 12, 12A...luminous layer, 13, 13A...second light-emitting layer, d1...first direction, d2...second direction, ds...display surface, L...external light, SE...illuminance sensor.

Claims

1. A display device comprising: a first light-emitting layer that emits light in a first direction that is a direction toward which a display surface is facing; a light-storing layer that is provided on a second direction side of the first light-emitting layer and stores light received from the first direction side, the second direction being the opposite direction to the first direction; and a second light-emitting layer that is provided between the first light-emitting layer and the light-storing layer and emits light toward the light-storing layer, wherein the power consumption of the second light-emitting layer is lower than the power consumption of the first light-emitting layer, and the light-storing layer stores light from at least the second light-emitting layer and emits light in the first direction.

2. The display device of claim 1, further comprising: an illuminance sensor that acquires an illuminance representing the brightness of light illuminating a display surface of the display device; and a control unit that controls, in a first case where the illuminance exceeds a given threshold value or is equal to or greater than the threshold value, to cause the first light-emitting layer to emit light and not cause the second light-emitting layer to emit light, and to cause the phosphorescent layer to emit light, in a second case where the illuminance is equal to or less than the threshold value.

3. The display device according to claim 2, wherein in the second case, the control unit causes the second light-emitting layer to emit light, thereby causing the phosphorescent layer to store and emit light.

4. The display device according to claim 3, wherein the control unit causes the second light-emitting layer to emit light when the amount of light emitted from the phosphorescent layer is less than a predetermined level.

5. The display device according to claim 3, wherein the control unit stops the emission of light from the second light-emitting layer when a given emission time has elapsed since the second light-emitting layer was made to emit light.

6. A display device according to claim 2, wherein in the first case, the phosphorescent layer stores external light that illuminates the display surface and emits light in the first direction.

7. The display device according to claim 1, wherein the display device is a self-luminous display device, and the first light-emitting layer includes elements that emit light in a plurality of different colors.

8. The display device of claim 1, wherein the display device is a liquid crystal display device, and the first light-emitting layer is a backlight for a liquid crystal contained in the liquid crystal display device.