JP4453406B2 - Display panel and display device - Google Patents

Description

  The present invention relates to a display panel and a display device, and more particularly to a display panel technique used in a display device that can be controlled by light.

  Conventionally, as an image display device, for example, an organic electroluminescence (hereinafter referred to as “EL”) display is used. As an organic EL display technology, for example, there is one proposed in Non-Patent Document 1.

“Organic EL materials and displays”, CMC, ISBN: 4-88231-284-0 C3054, Chapter 19, “Drive methods for organic EL displays”, Shingo Kawashima, p. 279-289

  A conventional organic EL display has a thin film transistor (hereinafter referred to as “TFT”) element. Each TFT element is controlled to be turned on and off by an access using current. When the number of pixels is increased as the screen size is increased, the number of TFT elements is also increased. In this case, the configuration of the organic EL display becomes complicated, and it becomes difficult to make the TFT elements have uniform performance. Further, when the number of TFT elements increases, the wiring also increases, and the electrical resistance of the organic EL display also increases. For this reason, it is difficult to enlarge the display.

  Therefore, it is considered to use a display panel that can be controlled by irradiating control light to a display device using EL elements. If the control light can be controlled, the display panel can be controlled by causing the display panel to scan with the control light corresponding to the image signal. Regardless of electrical access, a display panel using control light does not require a TFT element. For this reason, if control light is used, it is thought that a display can be made into a simple structure and can be enlarged easily. Control of the display panel by scanning the control light is hereinafter referred to as control by optical addressing.

  Here, consider a case where optical addressing is performed using a single laser beam as the control light. For example, when 1024 × 768 pixels are displayed on the display panel, the maximum time for irradiating control light to one pixel corresponds to 1 / 786,432 of the period of one frame of an image. If the period of one frame of the image is 1/60 second, this time is a very short time of about 20 nanoseconds. In the case of using a photoelectric conversion layer such as amorphous silicon (hereinafter referred to as “a-Si”), the light emission time of the EL element is considered to be on the order of microseconds depending on the sensitivity speed of the photoelectric conversion layer. When the EL element emits light in the order of microseconds, the amount of light is insufficient to display an image, and the display image becomes dark. Therefore, in order to display a bright image, it is necessary to increase the light amount of the EL element to several hundred thousand times, for example.

  The EL element can increase the peak luminance when pulse driving is performed rather than DC driving. In addition to increasing the light amount of the EL element itself, it is conceivable to increase the light amount of the display panel by using a plurality of control lights. However, the amount of light of the EL element is only increased by about 100 times as compared with the case of direct current by pulse driving. Further, in order to brighten the display panel by increasing the number of control lights, it is necessary to use several thousand or more control lights even when pulse driving is used together. When optical addressing is performed with several thousand or more control lights, the display device becomes complicated and expensive. As described above, a display panel that performs control by optical addressing has a problem that it is difficult to display a bright image, although it has an advantage of being able to have a simple configuration. The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a display panel and a display device that can display a bright image with an inexpensive configuration using control by optical addressing. .

  In order to solve the above-described problems and achieve the object, according to the present invention, an optically transparent first transparent electrode layer, a second transparent electrode layer, and a first transparent electrode layer are provided. A first variable electrode layer, and an EL layer that is provided between the variable conductivity layer and the second transparent electrode layer and emits light when a voltage is applied. A predetermined voltage is applied between the first transparent electrode layer and the second transparent electrode layer, and the electrical conductivity of the variable conductivity layer changes according to the amount of control light transmitted through the first transparent electrode layer, In the EL layer, the conductivity of the conductivity variable layer changes according to the amount of control light transmitted through the first transparent electrode layer, and a voltage corresponding to the conductivity of the conductivity variable layer is applied among predetermined voltages. Furthermore, the EL layer has a conductivity variable layer according to the amount of emitted light supplied from the EL layer to the conductivity variable layer. Changes the electrical conductivity, it is possible to provide a display panel, wherein a voltage corresponding to the conductivity of the conductivity-variable layer of a predetermined voltage to emit light by being applied.

  When control light is incident on the conductivity variable layer, the conductivity of the conductivity variable layer increases in accordance with the amount of control light. In other words, the resistance value of the conductivity variable layer is reduced by the control light. At this time, if a voltage is applied between the first and second transparent electrodes, a current corresponding to the amount of control light flows through the EL layer. The EL layer supplies emitted light in all directions with a current corresponding to the amount of control light. For example, a hole transport layer is provided between the EL layer and the conductivity variable layer. Since this hole transport layer can be formed very thin, a part of the light emitted from the EL layer enters the conductivity variable layer.

  Next, the electrical conductivity of the variable conductivity layer changes according to the amount of emitted light supplied from the EL layer to the variable conductivity layer. The EL layer further emits light by a current corresponding to the conductivity of the conductivity variable layer. The EL layer continues to emit light even after the control light is not incident due to the light emitted from the EL layer itself entering the variable conductivity layer. Thus, the EL layer continues to emit light even after the control light is scanned, so that the light amount of the entire display panel can be increased particularly when the control light is scanned at a high speed. Further, the display panel can be brightened by increasing the light emission time without increasing the light emission amount at the peak of the EL layer. If it is not necessary to increase the light emission amount at the peak of the EL layer, it is possible to use a low-output light source for control light. As a result, a display panel capable of displaying a bright image with an inexpensive configuration can be obtained using control by optical addressing.

  According to a preferred aspect of the present invention, the conductivity variable layer has a conductivity such that the amount of light emitted from the EL layer is a predetermined ratio with respect to the amount of control light transmitted through the first transparent electrode layer. It is desirable to have a rate. For example, the amount of emitted light incident on the conductivity variable layer from the EL layer is made substantially the same as the amount of control light. In this case, even after the control light is scanned, the EL layer continues to emit light with substantially the same amount of light as when the control light is incident by the light from the EL layer.

  In addition, when the amount of emitted light incident on the conductivity variable layer from the EL layer is smaller than the amount of control light, the EL layer emits light with a smaller amount than when the control light is incident after scanning the control light. . Next, when a smaller amount of emitted light is incident on the conductivity variable layer than when the control light is incident, the EL layer emits light with a smaller amount of light. If this is repeated, the EL layer stops light emission after gradually decreasing the light amount. As described above, the light emission time of the EL layer can be appropriately set by setting the light amount of the light emitted from the EL layer to a predetermined ratio with respect to the light amount of the control light transmitted through the first transparent electrode layer. . Further, since it is not necessary to uniformly reset the light emission of the display panel, the light can be emitted for a certain period regardless of the position on the display panel. From this, the light quantity of the whole display panel can be increased and the whole display panel can be brightened. Thereby, the light emission time of the EL layer can be set as appropriate, and a bright display panel can be obtained throughout.

  In order to cause the EL layer to emit light accurately, the light emission state of the EL layer needs to be reset after the control light is scanned and before the next control light is scanned. If the configuration is such that the light emitted from the EL layer is attenuated, the amount of light emitted from the EL layer can be made substantially zero before the next control light scan. Further, since the light amount of the light emitted from the EL layer can be made substantially zero in substantially the same time for each pixel scanned with the control light, the light amount of the entire display panel can be made substantially uniform.

  Further, according to a preferred aspect of the present invention, the light amount of the emitted light from the EL layer supplied to the conductivity variable layer is further adjusted to be a predetermined ratio with respect to the light amount of the emitted light of the EL layer. It is desirable to have a light amount adjustment unit. By providing the light amount adjusting unit, the amount of light incident on the conductivity variable layer from the EL layer can be easily adjusted. Thereby, the light quantity of a display panel can be adjusted easily.

  In a preferred embodiment of the present invention, when the EL layer is the first EL layer, at least one second EL layer is further provided between the first EL layer and the second transparent electrode. In the second EL layer, the conductivity of the conductivity variable layer changes according to the amount of control light transmitted through the first transparent electrode layer, and the conductivity of the conductivity variable layer of a predetermined voltage depends on the conductivity. It is desirable to emit light when a voltage is applied. When control light enters the conductivity variable layer, current is supplied to the first EL layer and the second EL layer. Then, after the control light scans, the light emitted from the first EL layer is supplied to the conductivity variable layer, whereby current is supplied to the second EL layer. Thus, the first EL layer is used to supply current to the second EL layer. Then, the second EL layer supplies emitted light by the current from the first EL layer, thereby displaying an image. Two or more second EL layers may be provided. By increasing the number of second EL layers, a bright image can be easily obtained.

  As the conductivity variable layer, it is desirable to use a constant current element capable of supplying a current substantially constant regardless of the resistance value of the EL layer, for example, a-Si. When a constant current element is used as the conductivity variable layer, a substantially constant current can be supplied even if the number of second EL layers is increased. Even if the number of second EL layers is increased, the number of second EL layers can be increased any number of times as long as a substantially constant current can be supplied. The first EL layer may not emit light with a large amount of light with respect to the amount of control light. The emitted light for display can be increased by increasing the number of second EL layers. For this reason, a bright image can be displayed with the control light with less energy. As a result, a bright image can be obtained with low power consumption by using control light with lower output.

  As a preferred embodiment of the present invention, it is desirable that the EL layer and the second EL layer have a structure divided into a plurality of regions corresponding to pixels. As a result, a display panel that can display by emitting light for each pixel in accordance with the image signal can be obtained.

  Furthermore, according to the present invention, the display panel includes a display panel, a power source that applies a predetermined voltage to the display panel, and a control light optical system that supplies control light to the display panel. A display device characterized by being a panel is desirable. By using the above display panel, it is possible to display a bright image using control by optical addressing. Thereby, a display device capable of displaying a bright image using control by optical addressing can be obtained.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 shows a schematic configuration of a display device 100 according to Embodiment 1 of the present invention. In this embodiment, the configuration of the display device 100 will be described first, and then the configuration of the display panel 110 that supplies emitted light using control light will be described. The display device 100 includes a display panel 110, a power source 120, and a control light optical system 130. The display panel 110 displays an image with the emitted light Le from the organic EL layer 115. The control light optical system 130 supplies the control light Lc to the display panel 110.

  The substrate 112 is a parallel plate made of an optically transparent glass member. On the substrate 112, an optically transparent first transparent electrode layer 101 and a conductivity variable layer 102 are sequentially stacked. The first transparent electrode layer 101 can be composed of an ITO film. The conductivity variable layer 102 changes the electrical conductivity by the control light Lc transmitted through the first transparent electrode layer 101. For example, a-Si or a photosensitive organic film can be used for the conductivity variable layer 102. For example, it is desirable that a-Si contains hydrogen. Further, a-Si is formed by a vapor deposition method (CVD method). In a state where the control light Lc is not irradiated at all, a-Si functions as an insulating member having an electrical conductivity of approximately zero (that is, a resistance value of approximately infinite). On the other hand, when the a-Si is irradiated with the control light Lc, the conductivity increases (that is, the resistance value decreases) according to the amount of light. The region where the conductivity changes in the variable conductivity layer 102 is the region of the first transparent electrode layer 101 irradiated with the control light Lc.

  An organic EL layer 115 is provided on the conductivity variable layer 102. The organic EL layer 115 is configured by stacking a hole transport layer 103, a light emitting layer 104, and an electron transport layer 105 in this order. For the hole transport layer 103, for example, poly (ethylenedioxy) thiophene (PE-DOT) can be used. For the light emitting layer 104, for example, a polymer organic EL material such as a benzothiazole compound can be used. For the electron transport layer 105, for example, an electron transporting substance such as metallic calcium can be used. Since the hole transport layer 103, the light emitting layer 104, and the electron transport layer 105 are all about several tens of nm in thickness, they can be regarded as optically transparent.

  When a current flows through the organic EL layer 115, in the light emitting layer 104, holes from the hole transport layer 103 and electrons from the electron transport layer 105 are combined. The fluorescent material of the light-emitting layer 104 is excited by energy generated when holes and electrons are combined. A light emission phenomenon occurs when the excited fluorescent material returns to the ground state, and light Le is generated from the light emitting layer 104. Note that the hole-transporting layer 103 and the electron-transporting layer 105 are not provided, and the light-emitting layer 104 may be mixed with a hole-transporting material and an electron-transporting material.

  A second transparent electrode layer 106 is provided on the organic EL layer 115. Similar to the first transparent electrode layer 101, the second transparent electrode layer 106 can be composed of an ITO film. A sealing adhesive 111 is filled on the second transparent electrode layer 106 and around each layer from the first transparent electrode layer 101 to the second transparent electrode layer 106. A substrate 114 is provided on the sealing adhesive 111. Similar to the substrate 112, the substrate 114 is a parallel plate made of an optically transparent glass member. Each layer from the first transparent electrode layer 101 to the second transparent electrode layer 106 is sealed by filling a sealing adhesive 111 between the substrates 112 and 114. The sealing adhesive 111 is provided to prevent deterioration of the organic EL layer 115 due to absorption of moisture in the air and oxidation. The emitted light Le from the organic EL layer 115 passes through the sealing adhesive 111 and the substrate 114 and is emitted.

  The power source 120 is connected between the first transparent electrode layer 101 and the second transparent electrode layer 106. The power supply 120 applies a predetermined voltage between the first transparent electrode layer 101 and the second transparent electrode layer 106. As a method for stacking the layers constituting the display panel 110, a resistance heating vacuum deposition method, an electron beam heating vacuum deposition method, a sputtering method, an ion plating method, a casting method, a spin coating method, or the like can be used as appropriate.

  The control light optical system 130 is provided on the substrate 112 side with respect to the display panel 110. The control light source 132 supplies beam-shaped light, for example, control light Lc that is laser light. As the control light source 132, for example, a semiconductor laser element or a surface emitting laser element provided with a modulator can be used. The control light source 132 supplies the control light Lc modulated according to the image signal. The control light Lc from the control light source 132 is reflected by the galvanometer mirror 134 toward the display panel 110. Then, the control light Lc reflected in the direction of the display panel 110 enters the surface of the display panel 110 on the substrate 112 side.

  The galvanometer mirror 134 can be produced by, for example, MEMS (Micro Electro Mechanical Systems) technology. The galvanometer mirror 134 scans the control light Lc in two directions by rotating about two predetermined orthogonal axes. In this way, the control light optical system 130 scans the surface of the display panel 110 on the substrate 112 side with the control light Lc. As the control light Lc, light in a wavelength region that can change the electrical conductivity of the conductivity variable layer 102 is used. As the control light Lc, an ultraviolet laser, a visible light laser, or an infrared laser can be used. Further, not only laser light but also beam-like light, for example, light from a light emitting diode element (LED) may be used as the control light Lc.

  Next, the configuration of the display panel 110 for controlling the display panel 110 with the control light Lc and obtaining a bright image with the control light Lc will be described. The control light Lc from the control light optical system 130 passes through the substrate 112 of the display panel 110 and the first transparent electrode layer 101 and enters the conductivity variable layer 102. When the control light Lc having an intensity corresponding to the image signal enters the conductivity variable layer 102, the electrical conductivity of the portion at the incident position of the control light Lc increases according to the amount of the control light Lc. Strictly speaking, the region where the conductivity of the conductivity variable layer 102 changes tends to spread around the irradiation position in proportion to the intensity of the control light Lc and its irradiation time. Here, it is assumed that the control light Lc is scanned at high speed by the galvanometer mirror 134, and that the conductivity only changes in the vicinity of the region irradiated with the control light Lc.

  As the conductivity of the conductivity variable layer 102 increases, one electrode of the power source 120 connected to the first transparent electrode layer 101 has the first transparent electrode layer 101 and the conductivity variable layer 102 connected to each other. Via, it is electrically connected to the organic EL layer 115. The other electrode of the power source 120 is connected to the second transparent electrode layer 106. Since the conductivity of the variable conductivity layer 102 changes according to the light amount of the control light Lc transmitted through the first transparent electrode layer 101, a voltage corresponding to the light amount of the control light Lc is applied to the organic EL layer 115. Current flows. In this way, the organic EL layer 115 can emit light according to the control light Lc. The organic EL layer 115 emits light by current from the power source 120. From this, the organic EL layer 115 can supply the emitted light Le with energy larger than the energy of the control light Lc.

  As described above, the conductivity of the variable conductivity layer 102 changes only in the vicinity of the region irradiated with the control light Lc. Further, since the layers 103, 104, and 105 of the organic EL layer 115 are sufficiently small in thickness, the resistance value in the same horizontal direction as the surface of the substrate 112 is large with respect to the thickness direction of the organic EL layer 115. For this reason, the organic EL layer 115 is difficult to conduct in the lateral direction. For these reasons, even if each layer of the display panel 110 is formed uniformly without being divided into pixels, the organic EL layer 115 can emit light only at the position where the control light Lc is incident. By controlling the position where the control light Lc is incident using the control light optical system 130, the organic EL layer 115 can emit light for each pixel in accordance with the image signal, and an image can be displayed.

  FIGS. 2A and 2B are explanatory diagrams of the operation of the display panel 110 for obtaining a bright image by the display panel 110 by the control light Lc. For the sake of explanation, in FIGS. 2A and 2B, only the conductivity variable layer 102 and the light emitting layer 104 of the display panel 110 are illustrated. The light emitting layer 104 shown in FIG. 2A supplies the emitted light Le having the predetermined energy Ee in all directions when the control light Lc having the predetermined energy Ec is incident.

The energy Ee of the emitted light Le varies depending on the amount of current that can be conducted to the conductivity variable layer 102. In the following description, the ratio of the energy Ee of the emitted light Le to the energy of the incident light to the conductivity variable layer 102 is expressed as a gain G. The gain G is a value that varies depending on the property of the conductivity variable layer 102. When the control light Lc having the energy Ec is incident on the conductivity variable layer 102 and the emission light Le having the energy Ee is supplied, the gain G is calculated by the following equation.
G = Ee / Ec
When the energy Ec of the control light Lc is set to a predetermined value, the display panel 110 can obtain a brighter image as the gain G increases.

  For example, consider a case where the gain G of the display panel 110 is 5. The display panel 110 supplies emitted light Le having an energy Ee of 500 from the light emitting layer 104 in all directions by the control light Lc having an energy Ec = 100. A part of the light Lr supplied from the light emitting layer 104 in all directions travels in the direction of the conductivity variable layer 102. Since the electron transport layer 105 (see FIG. 1) provided between the conductivity variable layer 102 and the light emitting layer 104 is sufficiently thin, it can be regarded as optically transparent. Therefore, the light Lr traveling from the light emitting layer 104 toward the variable conductivity layer 102 can enter the variable conductivity layer 102.

  It is assumed that light Lr with energy Er = 100 corresponding to one-fifth of energy Ee is incident on the conductivity variable layer 102 with respect to emitted light Le with energy Ee = 500. When the light Lr enters the conductivity variable layer 102, the control light Lc and the light Lr enter the conductivity variable layer 102 at the same time. The conductivity variable layer 102 changes its conductivity according to the amount of light having an energy of 200 (= Ec + Er) by the simultaneous incidence of the control light Lc and the light Lr.

  When light having an energy of 200 is incident, the display panel 110 having G = 5 supplies emitted light Le having energy Ee = 1000 from the light emitting layer 104 in all directions. Then, as shown in FIG. 2B, after scanning with the control light Lc, the light Lr with energy Er = 200 corresponding to one-fifth of the energy Ee with respect to the emitted light Le with energy Ee = 1000 is conductivity. The light enters the variable layer 102. When the light Lr with energy Er = 200 enters the conductivity variable layer 102, the display panel 110 with G = 5 supplies the emitted light Le with energy Ee = 1000.

  FIG. 3 shows a change in the amount of light emitted from the display panel 110 since the control light Lc is incident. In the graph shown in FIG. 3, the vertical axis represents the light amount of an arbitrary unit, and the horizontal axis represents time. The display panel 110 continues to emit light with its own emission light Le having energy Ee = 1000 even after scanning with the control light Lc. Accordingly, the display panel 110 continues to emit light with a constant light amount I1 as shown in FIG. In this embodiment, the gain G of the display panel 110 depends on the voltage applied by the power source 120 in addition to the conductivity variable layer 102 to be formed such as the film thickness of the conductivity variable layer 102 and the content of impurities such as boron and phosphorus. It can be set appropriately. In the above description, the units of light energy Ee, Ec, Er are not particularly mentioned, but the gain G can be determined, for example, with the unit of light energy as watts (W).

  The organic EL layer 115 continues to emit light even after the control light Lc is scanned, so that the amount of light of the entire display panel 110 can be increased particularly when the control light Lc is scanned at high speed. In addition, the display panel 110 of this embodiment can easily brighten the display panel 110 by increasing the time during which the organic EL layer 115 emits light. Since the amount of light can be increased by increasing the light emission time of the organic EL layer 115, it is not necessary to increase the light emission amount of the organic EL layer 115 at the moment when the control light Lc is incident.

  If the light emission amount at the peak of the organic EL layer 115 does not need to be increased, the low-output light source 132 for control light can be used. For this reason, the display device 100 can be made inexpensive by using the low-output inexpensive light source 132 for control light. Thereby, there is an effect that a bright image can be displayed with an inexpensive configuration using control by optical addressing. When the control by optical addressing is used, it is not necessary to provide a complicated circuit such as a TFT element on the display panel 110. Therefore, the display panel 110 can have a simple configuration and can be easily enlarged. Another point that the display device 100 is suitable for upsizing is that the organic EL layer 115 is self-luminous and thus no other light source device is required. Furthermore, compared with a liquid crystal panel, the display panel 110 can obtain a high-contrast image. Compared with a plasma display, the display panel 110 can be driven at a lower voltage. For this reason, the display device 110 may be configured to have low power consumption by using an inexpensive driving circuit.

  As described above, in the display panel 110 according to the present embodiment, the light Lr having the energy Er corresponding to one fifth of the energy Ee out of the emitted light Le is incident on the conductivity variable layer 102. When the gain G = 5, the light Lr having an energy corresponding to 1/5 that is the reciprocal of the gain G with respect to the emitted light Le is incident on the conductivity variable layer 102. At this time, the light amount of the light Lr incident on the variable conductivity layer 102 from the organic EL layer 115 and the light amount of the control light Lc are substantially the same. Therefore, since the amount of incident light to the conductivity variable layer 102 is maintained, the organic EL layer 115 can continue to emit light.

  In this way, by setting the gain G to a predetermined value and making the light having the energy 1 / G reciprocal of the gain G out of the emitted light Le of the organic EL layer 115 incident on the conductivity variable layer 102, the organic EL layer 115. Can continue to emit light. Further, for example, when the light emitting layer 104 and the variable conductivity layer 102 are provided sufficiently close to each other, light having energy corresponding to substantially half of the light emitted from the light emitting layer 104 travels in the direction of the variable conductivity layer 102. It becomes the composition to do. At this time, the organic EL layer 115 can continue to emit light by setting the display panel 110 to a gain G = 2.

  If the organic EL layer 115 continues to emit light after the incidence of the control light Lc once, a plurality of displays cannot be performed according to the image signal. Therefore, the display panel 110 needs to reset the light emission of the organic EL layer 115 by turning off the power source 120 or the like until the next control light Lc is incident. When the control light Lc can be scanned over the entire surface of the display panel 110 in a very short time, display according to the image signal can be performed by turning off the power source 120 for each frame period of the image. Further, the configuration is not limited to the configuration in which the control light Lc is scanned. For example, the configuration may be such that the control light is incident on the display panel 110 using a surface light source. Also in this case, display according to the image signal can be performed by turning off the power source 120 for each frame period of the image.

  FIG. 4 shows a schematic configuration of a display device 400 according to the second embodiment of the present invention. The same parts as those of the display device 100 of the first embodiment are denoted by the same reference numerals, and redundant description is omitted. The display device 400 of the present embodiment is characterized in that the light amount of the emitted light Le from the organic EL layer 115 gradually attenuates after the control light Lc is scanned. The display panel 410 includes an aluminum layer 407 between the conductivity variable layer 102 and the hole transport layer 103.

  FIGS. 5A and 5B are explanatory diagrams of the operation of the display panel 410 that gradually attenuates the light amount of the emitted light Le from the organic EL layer 115 after the control light Lc is scanned. The light emitting layer 104 shown in FIG. 5A supplies the emitted light Le having the predetermined energy Ee in all directions when the control light Lc having the predetermined energy Ec is incident. A part of the light Lr of the emitted light Le supplied from the light emitting layer 104 in all directions is incident on the aluminum layer 407.

  The aluminum layer 407 transmits a part of the light traveling from the organic EL layer 115 toward the conductivity variable layer 102. The light transmitted through the aluminum layer 407 enters the conductivity variable layer 102. The aluminum layer 407 also has a characteristic of reflecting a part of light traveling from the organic EL layer 115 toward the conductivity variable layer 102 toward the organic EL layer 115. The aluminum layer 407 sets the amount of light supplied to the conductivity variable layer 102 to a predetermined value in accordance with the amount of light transmitted and reflected from the organic EL layer 115. The aluminum layer 407 adjusts the light quantity of the light from the organic EL layer 115 supplied to the conductivity variable layer 102 so that the light quantity of the whole light emission light Le of the organic EL layer 115 is a predetermined ratio. It is an adjustment part.

  Also in this embodiment, a case where the gain G = 5 is considered as in the first embodiment. The display panel 410 supplies emitted light Le having an energy Ee of 500 from the light emitting layer 104 in all directions by the control light Lc having an energy Ec = 100. Then, it is assumed that light Lr having an energy Er = 80, which is 0.16 times that of the emitted light Le having an energy Ee = 500, is incident on the conductivity variable layer 102 by adjusting the amount of light by the aluminum layer 407. At this time, the conductivity of the variable conductivity layer 102 changes according to the amount of light having an energy of 180 (= Ec + Er) when the control light Lc and the light Lr are simultaneously incident.

  When light having an energy of 180 is incident, the display panel 110 having G = 5 supplies emitted light Le having energy Ee = 900 in all directions from the light emitting layer 104. As shown in FIG. 5B, after scanning with the control light Lc, the light Lr2 with energy Er = 144 corresponding to 0.16 times the energy Ee is compared with the emission light Le2 with energy Ee = 900. The light enters the variable layer 102. When the light Lr2 with energy Er = 144 is incident on the conductivity variable layer 102, the display panel 110 with G = 5 supplies the emitted light Le2 with energy Ee = 720.

  If the same calculation is performed thereafter, the energy Ee of the emitted light Le2 decreases to 720, 576, 460.8, and 368.6. The light Lr2 incident on the variable conductivity layer 102 also decreases to 115.2, 92.16, and 73.73. In this way, both the light Lr2 and the emitted light Le2 incident on the conductivity variable layer 102 are attenuated. Finally, the light amount of the emitted light Le2 becomes 0 (zero).

  FIG. 6 shows a change in the amount of light emitted from the display panel 410 since the control light Lc is incident. In the graph shown in FIG. 6, the vertical axis represents the light quantity in an arbitrary unit, and the horizontal axis represents time. The amount of light emitted from the display panel 410 is attenuated with the amount of light I2 when the control light Lc is incident as a peak, and becomes 0 (zero) at time tF. When the time tF at which the amount of light emitted from the display panel 410 is 0 (zero) is shorter than the period of one frame of the image, it is not necessary to reset the light emission of the organic EL layer 115 every frame of the image.

  Further, consider a case where the time for the control light Lc to scan the entire surface of the display panel once and the period of one frame of the image are substantially the same. At this time, if the power supply 120 is turned off every frame period, the display panel is reset immediately after scanning with the control light Lc at the scanning light Lc scanning end position. For this reason, an image with a dark part is displayed because the time during which the emitted light can be supplied differs depending on the position on the display panel. The display panel 410 of this embodiment can supply emitted light over substantially the same time regardless of the position on the display panel 410. Therefore, it is possible to obtain an image with substantially uniform brightness throughout.

  In the display panel 410 of this embodiment, the amount of emitted light corresponding to the image signal corresponds to the integral value of the graph shown in FIG. Here, it is assumed that the time tF from when the control light Lc is incident until the light amount of the emitted light becomes 0 (zero) is substantially constant regardless of the light amount I2 when the control light Lc is incident. The display panel 410 can emit light according to the image signal by adjusting the light amount I2 when the control light Lc is incident. For example, the time tF can be shortened by reducing the energy of light incident on the conductivity variable layer 102 from the organic EL layer 115. The light emission time of the organic EL layer 115 can be appropriately set according to the amount of light transmitted through the aluminum layer 407.

  As described above, by setting the gain G as a predetermined value and making the light having an energy smaller than 1 / G reciprocal of the gain G out of the emitted light Le of the organic EL layer 115 enter the conductivity variable layer 102, the organic EL layer 115 emitted light can be attenuated. Further, as in the first embodiment, the light amount of the entire display panel 110 can be increased by continuing to emit light from the organic EL layer 115 for a certain period after the control light Lc is scanned. In addition, the display panel 110 of this embodiment can make the display panel 110 brighter by increasing the time during which the organic EL layer 115 emits light. Thereby, the light emission time of the organic EL layer 115 can be set as appropriate, and an effect is obtained that a bright image can be obtained over the whole.

  Further, by providing the aluminum layer 407, the amount of light incident on the conductivity variable layer 102 from the organic EL layer 115 can be easily adjusted. If the amount of light incident on the conductivity variable layer 102 can be easily adjusted, the light emission time of the organic EL layer 115 can be easily set. Thereby, there is an effect that the amount of light of the display panel 410 can be easily adjusted. In addition, as a light quantity adjustment part, it is good not only as a structure which provides the aluminum layer 407 but the layer of another metal member. Further, as the light amount adjusting unit, a semi-transmissive film that transmits only a part of the light Lr out of the light from the organic EL layer 115 may be used.

  Further, the semi-transmissive film may be configured to reflect light other than the transmitted light Lr in the light from the organic EL layer 115 in the direction of the organic EL layer 115. By reflecting other light in the direction of the organic EL layer 115 and emitting it from the substrate 114, it can be used as display light. For this reason, the light utilization efficiency can be improved by using a transflective film that reflects light other than the light Lr incident on the conductivity variable layer 102 in the direction of the organic EL layer 115.

  FIG. 7 shows a schematic configuration of a display device 700 according to Embodiment 3 of the present invention. The same parts as those of the display device 100 of the first embodiment are denoted by the same reference numerals, and redundant description is omitted. The display device 700 of this embodiment includes second organic EL layers 715, 725, and 735. The display panel 770 is configured by sequentially laminating a current supply layer 710 and three image display layers 720, 730, and 740 between the substrate 112 and the second transparent electrode layer 106. The current supply layer 710 is configured by laminating a first transparent electrode layer 101, a conductivity variable layer 102, a first organic EL layer 115, and an aluminum layer 707 in this order.

  The three image display layers 720, 730, and 740 are provided between the aluminum layer 707 on the first organic EL layer 115 and the second transparent electrode layer 106. Each of the image display layers 720, 730, and 740 is configured by sequentially laminating transparent electrode layers 711, 721, and 731 and second organic EL layers 715, 725, and 735. The second organic EL layers 715, 725, and 735 all have the same configuration as the first organic EL layer 115. A second transparent electrode layer 106 is laminated on the second organic EL layer 735 of the third image display layer 740.

  By making the control light Lc incident on the display panel 110, the first organic EL layer 115 supplies the emitted light Lc 'in all directions. The first organic EL layer 115 supplies a part of the emitted light Lc ′ to the conductivity variable layer 102 as in the first and second embodiments. The current supply layer 710 can supply current to the image display layers 720, 730, and 740 through the aluminum layer 707 by the conduction of the variable conductivity layer 102. Note that the aluminum layer 707 has a thickness that does not transmit light. For this reason, the light that is supplied in the direction opposite to the conductivity variable layer 102 of the emitted light Lc ′ is reflected by the aluminum layer 707 and supplied to the conductivity variable layer 102, and thus is not used for image display. . As described above, the current supply layer 710 has only a function of supplying current to the image display layers 720, 730, and 740.

  The second organic EL layers 715, 725, and 735 supply the emitted light Le when the conductivity variable layer 102 becomes conductive. Since the aluminum layer 707 has a thickness that does not transmit light, light traveling from the second organic EL layers 715, 725, and 735 toward the substrate 112 is reflected by the aluminum layer 707. . Then, the light reflected by the aluminum layer 707 travels toward the substrate 114. As described above, the aluminum layer 707 functions as an electrode that supplies current to the image display layers 720, 730, and 740, and serves as a reflection portion that reflects light emitted from the second organic EL layers 715, 725, and 735. With functions. The display panel 770 displays an image with the emitted light Le from the second organic EL layers 715, 725, and 735.

  Similar to Example 1 and Example 2, the conductivity variable layer 102 was scanned with the control light Lc when a part of the emitted light Lc ′ from the organic EL layer 115 was incident on the conductivity variable layer 102. It becomes conductive afterwards. Since the conductivity variable layer 102 becomes conductive, the current supply layer 710 can continuously supply current to the image display layers 720, 730, and 740 even after the control light Lc is scanned. Accordingly, the display device 700 of this embodiment can continue to emit the second organic EL layers 715, 725, and 735 even after the control light Lc is scanned, as in the first and second embodiments.

  Furthermore, the display panel 770 of this embodiment can display an image with the three organic EL layers 715, 725, and 735. For this reason, there is an effect that a bright image can be displayed more easily than when one organic EL layer is used. Note that the number of the second organic EL layers is not limited to three, and any number may be provided. As the quantity of the second organic EL layer is increased, the image of the display device 700 can be brightened.

  As the conductivity variable layer 102, it is desirable to use a constant current element capable of supplying a current substantially constant regardless of the resistance value of each organic EL layer, for example, a-Si. When a constant current element is used as the conductivity variable layer 102, a substantially constant current can be supplied even if the number of second organic EL layers is increased. Even if the number of second organic EL layers is increased, the number of second organic EL layers can be increased any number of times as long as a substantially constant current can be supplied.

  The emitted light Lc ′ from the first organic EL layer 115 is not used for image display. For this reason, the gain G of the current supply layer 710 may be a low value of about 1.1, for example. If bright light Le can be supplied in the image display layers 720, 730, and 740, a bright image can be displayed with the control light Lc with less energy. Accordingly, a bright image can be obtained with low power consumption by using the control light source 132 with lower output.

  FIG. 8 is a diagram showing a schematic configuration of a display device 800 according to Embodiment 4 of the present invention. The same parts as those of the display device 100 of the first embodiment are denoted by the same reference numerals, and redundant description is omitted. The display device 800 of this embodiment is characterized in that the organic EL layer 815 has a structure divided into a plurality of regions corresponding to pixels. A plurality of banks 808 as partition members are provided on the conductivity variable layer 102 of the display panel 810.

  The bank 808 is an electrically insulating member provided linearly in two directions substantially orthogonal to each other in a region in a plane substantially parallel to the substrate 112. The bank 808 can be formed by, for example, polyimide using an inkjet method, etching, or patterning. When cut along a plane substantially perpendicular to the surface of the substrate 112, the bank 808 has a substantially isosceles triangular shape as shown in FIG.

  An organic EL layer 815 is provided in a region on the conductivity variable layer 102 partitioned by the bank 808. The organic EL layer 815 has a configuration similar to that of the organic EL layer 115 (see FIG. 1) of the first embodiment. The organic EL layer 815 can be formed by sequentially stacking a hole transport layer 803, a light emitting layer 804, and an electron transport layer 805 in each region divided by the bank 808 by an inkjet method. A pixel is configured by an organic EL layer 815 divided by a bank 808. By providing the bank 808, each pixel is arranged in a matrix.

  Thus, the display panel 810 has a structure in which the organic EL layer 815 is divided into a plurality of regions corresponding to pixels. The R light emitting layer 804R, the G light emitting layer 804G, and the B light emitting layer 804B cause a light emission phenomenon in the same manner as the light emitting layer 104 of Example 1 (see FIG. 1). Note that since the electron transport layer 805 has a sufficiently small thickness, the resistance value in the same horizontal direction as the surface of the substrate 112 is large with respect to the thickness direction of the electron transport layer 805. For this reason, the electron transport layer 805 does not conduct in the lateral direction even if the division by the bank 808 is incomplete as shown in FIG. For this reason, even if the electron transport layer 805 is not completely divided by the bank 808, light can be emitted according to the image signal for each pixel.

  The light emitting layer for R light 804R, the light emitting layer for G light 804G, and the light emitting layer for B light 804B have different wavelength ranges depending on the energy generated when the respective fluorescent substances return to the ground state after being excited. Light is generated. Then, by generating light in different wavelength regions, the R light emitting layer 804R, the G light emitting layer 804G, and the B light emitting layer 804B generate R light, G light, and B light, respectively. .

  In the display device 800 shown in FIG. 8, the control light Lc is incident on the first transparent electrode layer 101 at a position corresponding to the B light emitting layer 804B. As described in the first embodiment, the conductivity variable layer 102 changes the electrical conductivity of the portion where the control light Lc is incident. For this reason, when the control light Lc is incident on the position corresponding to the B light emitting layer 804B, the B light emitting layer 804B can supply the emitted light Le. R light and G light can be supplied not only to the B light emitting layer 804B but also to the other light emitting layers 804R and 804G in the same manner as the B light emitting layer 804B. Accordingly, there is an effect that a bright color image can be displayed by emitting light for each pixel according to the image signal.

(Modification 1 of Example 4)
FIG. 9 is a diagram illustrating a schematic configuration of a display device 900 according to the first modification of the fourth embodiment. In the display device 900 of this modification, a second organic EL layer 915 having a structure divided into a plurality of regions corresponding to pixels between the first organic EL layer 115 and the second transparent electrode layer 106. Is provided. The bank 808 is provided on the electron transport layer 105 of the first organic EL layer 115. An electrode layer 907 and a second organic EL layer 915 are provided in a region on the first organic EL layer 115.

  The electrode layer 907 is configured by laminating a transparent electrode layer on an aluminum layer, like the display device 700 of the third embodiment. Similarly to the organic EL layer 815 (see FIG. 8), the second organic EL layer 915 is formed by sequentially stacking a hole transport layer 903, a light emitting layer 904, and an electron transport layer 905 in each region divided by the bank 808. Configured. The light emitting layer 904 of the second organic EL layer 915 is divided by a bank 808 into an R light emitting layer 904R, a G light emitting layer 904G, and a B light emitting layer 904B.

  The display device 900 of this modification is the same as the display device 800 described above in that it has a pixel structure. Further, the second organic EL layer 915 is provided between the first organic EL layer 115 and the second transparent electrode layer 106, and is the same as the display device 700 of the third embodiment. By adopting a configuration in which not only the second organic EL layer 915 but also the electrode layer 907 is partitioned by the bank 808, the second organic EL layer corresponds to the position of the first transparent electrode layer 101 on which the control light Lc is incident. A current can be supplied to 915. Thus, it is possible to easily display a bright color image by emitting light for each pixel in accordance with the image signal.

(Modification 2 of Example 4)
FIG. 10 is a diagram illustrating a schematic configuration of a display apparatus 1000 according to the second modification of the fourth embodiment. The display device 1000 according to the present modification includes the organic EL layers 1015 and 1025 divided into a plurality of regions corresponding to the pixels on the organic EL layer 1005 divided into a plurality of regions corresponding to the pixels. Features. The display panel 1070 is configured by sequentially stacking three layers 1010, 1020, and 1030 each having an organic EL layer.

  The first layer 1010 is formed by laminating the first transparent electrode layer 101, the conductivity variable layer 102, and the organic EL layer 1005 in this order. The organic EL layer 1005 is divided by a bank 808 provided on the conductivity variable layer 102. The second layer 1020 is provided by stacking a transparent electrode layer 1011 and an organic EL layer 1015. Both the transparent electrode layer 1011 and the organic EL layer 1015 are divided by a bank 808 provided on the first layer 1010. The third layer 1030 is provided by stacking a transparent electrode layer 1021 and an organic EL layer 1025. Both the transparent electrode layer 1021 and the organic EL layer 1025 are divided by a bank 808 provided on the second layer 1020.

  The layers 1010, 1020, and 1030 are provided so that the R light emitting layer, the G light emitting layer, and the B light emitting layer formed by the bank 808 are at corresponding positions in the emission direction of the emitted light Le. By configuring the display panel 1070 with such a layer structure, it is possible to easily display a bright color image by causing each pixel to emit light according to an image signal, similarly to the display panel 910 of the first modification. Also in the present modification, the first organic EL layer only for supplying current to the organic EL layers 1005, 1015, and 1025 may be provided in the same manner as in the first modification. In addition, although the display apparatus of each said Example uses the organic electroluminescent layer for the display panel, if it light-emits by applying a voltage, it will not be restricted to this. For example, an inorganic EL layer may be used instead of the organic EL layer.

  As described above, the display device according to the present invention is useful when displaying a presentation or a moving image.

1 is a schematic configuration diagram of a display device according to Embodiment 1 of the present invention. Explanatory drawing of an effect | action of a display panel. Explanatory drawing of an effect | action of a display panel. The figure which shows the change of the emitted light amount of a display panel. The schematic block diagram of the display apparatus which concerns on Example 2 of this invention. Explanatory drawing of an effect | action of a display panel. Explanatory drawing of an effect | action of a display panel. The figure which shows the change of the emitted light amount of a display panel. FIG. 6 is a schematic configuration diagram of a display device according to Example 3 of the invention. FIG. 6 is a schematic configuration diagram of a display device according to Example 4 of the invention. FIG. 10 is a schematic configuration diagram of a display device according to a first modification of the fourth embodiment. FIG. 10 is a schematic configuration diagram of a display device according to a second modification of the fourth embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 Display apparatus, 101 1st transparent electrode layer, 102 Conductivity variable layer, 103 Hole transport layer, 104 Light emitting layer, 105 Electron transport layer, 106 2nd transparent electrode layer, 110 Display panel, 111 Adhesion for sealing Agent, 112, 114 substrate, 115 organic EL layer, 120 power supply, 130 optical system for control light, 132 light source for control light, 134 galvano mirror, 400 display device, 407 aluminum layer, 410 display panel, 700 display device, 707 aluminum Layer, 710 current supply layer, 711 transparent electrode layer, 715, 725, 735 organic EL layer, 720, 730, 740 image display layer, 770 display panel, 800 display device, 803 hole transport layer, 804 light emitting layer, 804R R Light emitting layer for light, 804G G light emitting layer, 804B B light emitting layer, 805 Child transport layer, 808 bank, 810 display panel, 815 organic EL layer, 900 display device, 903 hole transport layer, 904 light emitting layer, 904R R light emitting layer, 904G G light emitting layer, 904B B light emitting layer , 905 Electron transport layer, 907 electrode layer, 910 display panel, 915 organic EL layer, 1000 display device, 1005, 1015, 1025 organic EL layer, 1010 first layer, 1011, 1021 transparent electrode layer, 1020 second layer 1030 Third layer, 1070 Display panel, Lc control light, Le, Le2, Lc ′ emission light

Claims (4)

An optically transparent first transparent electrode layer and a second transparent electrode layer;
A conductivity variable layer provided on the first transparent electrode layer;
A light amount adjusting unit provided on the conductivity variable layer;
An electroluminescence layer that is provided between the light amount adjustment unit and the second transparent electrode layer and emits light when a voltage is applied;
A predetermined voltage is applied between the first transparent electrode layer and the second transparent electrode layer,
The electrical conductivity variable layer changes in electrical conductivity according to the amount of control light transmitted through the first transparent electrode layer,
In the electroluminescence layer, the conductivity of the conductivity variable layer changes according to the amount of the control light transmitted through the first transparent electrode layer, and the conductivity variable layer of the predetermined voltage is changed. Light is emitted by applying a voltage according to the conductivity,
Further, in the electroluminescence layer, the electrical conductivity of the conductivity variable layer changes according to the amount of light emitted from the electroluminescence layer to the conductivity variable layer, and the predetermined voltage is applied. Emits light when a voltage corresponding to the conductivity of the conductivity variable layer is applied ,
The light amount adjusting unit adjusts the light amount of the emitted light supplied from the electro-luminescence layer to the conductivity variable layer so as to have a predetermined ratio with respect to the light amount of the emitted light of the electro-luminescence layer. ,
The predetermined ratio is set such that the amount of emitted light supplied from the electroluminescence layer to the conductivity variable layer is less than the amount of control light transmitted through the first transparent electrode layer,
The display panel, wherein light emission of the electroluminescence layer stops at a predetermined time . In the case where the electroluminescence layer is the first electroluminescence layer, at least one second electroluminescence layer is further provided between the first electroluminescence layer and the second transparent electrode. Have
In the second electroluminescence layer, the conductivity of the variable conductivity layer varies according to the amount of the control light transmitted through the first transparent electrode layer, and the conductivity of the predetermined voltage is changed. The display panel according to claim 1, wherein the display panel emits light when a voltage corresponding to the conductivity of the variable layer is applied. The electroluminescence layer and the second electroluminescence layer display panel according to any one of claims 1-2, characterized in that forming a structure divided into a plurality of regions corresponding to the pixels . A display panel;
A power source for applying a predetermined voltage to the display panel;
A control light optical system for supplying control light to the display panel,
The display panel display device which is a display panel according to any one of claims 1-3.

Images