JP3993221B2 - Display device - Google Patents

Description

  The present invention relates to a non-light emitting display device such as a liquid crystal display device, and a display device such as a light emitting display device using an organic EL light emitting element. Specifically, the present invention relates to a display device in which a non-light emitting display area and a light emitting display area are provided in the display area.

  In recent years, mobile information terminals (PDA: Personal Data Assistant) and the like have become widespread, including mobile phones. Along with this, development of displays for displaying information mounted on these terminals has become very active in recent years.

  The display is roughly classified into a non-light emitting display device and a light emitting display device. The former performs display by modulating light from an external light source such as sunlight, room light, backlight, or front light by a light modulation element, and a liquid crystal display element is known as a representative. On the other hand, the latter does not require an external light source, and the light emitting element emits light for display, and EL (Electro Luminescence) is attracting much attention as a representative. Hereinafter, these display devices will be described in more detail.

  First, in a transmissive liquid crystal display device that is a non-light-emitting display device using an external light source, the backlight is used as a light source, which increases power consumption and enlarges the shape, leaving problems for portable use. Therefore, in order to reduce power consumption, which is one of the above problems, the lower electrode of the liquid crystal layer is formed of a metal that reflects light such as aluminum, so that external light such as sunlight or indoor light is used as a light source. Reflective liquid crystal display devices have been developed. However, this reflection type liquid crystal display device has difficulty in use in a dark place because it uses external light.

  In order to solve these problems, the lower electrode of the liquid crystal layer is formed with a half mirror, and in a bright environment, a reflective display is performed without using a backlight, and in a dark place, the backlight is turned on to perform a transmissive display. A transflective display device was developed. However, since the transflective display device uses the contradictory characteristics of the portion that reflects light and the portion that transmits light, the light use efficiency is low and a decisive improvement for reducing power consumption has not been achieved.

  In order to solve these problems, the present inventors can use the liquid crystal display device that can be used as a reflective type that does not use a backlight in a bright environment, and can be used as a transmissive type by turning on the backlight in a dark place. (See Patent Document 1). This liquid crystal display device is different from a conventional liquid crystal display device using a reflector having a thin film thickness and semi-transparency, and each display pixel in the liquid crystal display device is divided into two regions, a reflective region and a transmissive region. It is divided into. That is, in the liquid crystal display device, a reflective electrode is formed as one region of each display pixel to be a reflective region, while a transmissive electrode is formed in another region of each display pixel to be a transmissive region. Further, the thickness of the liquid crystal layer in the reflective region is different from the thickness of the liquid crystal layer in the transmissive region. Thereby, it is possible to achieve optimum brightness in each of the reflective region and the transmissive region.

  However, in the above-described pixel-divided liquid crystal display device, the entire region of each pixel is irradiated with backlight light from the back, while the backlight light is used only in the transmission region of each pixel. Therefore, there has been a problem that the utilization efficiency of backlight light is low. In particular, when the area ratio of the reflective electrode is high, the transmission area is inevitably narrowed, so that the utilization efficiency of the backlight light is lowered.

  In view of this, for example, there is a pixel division type liquid crystal display device disclosed in Japanese Patent Application Laid-Open No. 2005-228405 as one that increases the use efficiency of the backlight for the pixel division type liquid crystal display device. In this liquid crystal display device 100, as shown in FIG. 15, first, by providing a transmissive opening 104 in a part of the reflective electrode 103 arranged in each pixel 102 in the liquid crystal panel 101, a pixel division type liquid crystal is provided. It is a display device. Further, in the liquid crystal display device 100, a light emitting element composed of an organic EL (Electro Luminescence) element 110 is used as a backlight, and the light emitting portions 111... Of the organic EL element 110 are arranged in the entire region of each pixel 102. Instead, it is arranged only in the region corresponding to the transmission openings 104. Thereby, since the patterned organic EL element is combined as a backlight, light utilization efficiency can be improved and power consumption can be reduced.

On the other hand, a display device using the organic EL light emitting element, which is representative of a light emitting display device, has a thin and lightweight feature, and since it is a light emitting element, it does not require a backlight like a liquid crystal display device and can be used even in a dark environment. Moreover, since almost all of the emitted light is used for display, the light utilization efficiency is high. However, a display device using this organic EL light emitting element must always emit light, and it is difficult to reduce power consumption because it is necessary to increase the amount of light emitted in order to improve the display quality particularly in a bright environment. It was.
Japanese Patent Laid-Open No. 11-101992 JP 2001-66593 A

  However, in the pixel division type liquid crystal display device shown in FIG. 15, the organic EL element 110 as the light emitting element is arranged outside the liquid crystal panel 101, so that the transmission opening 104 of the reflective electrode 103. Between the EL element 110, there are a phase difference plate 105, a polarizing plate 106, and two glass substrates, that is, a glass substrate 107 and a glass substrate 112. At present, a typical pixel pitch is about 80 microns, but in this case, the width of the transmissive aperture 104 is further reduced from one half to one sixth, approximately 15 microns to 40 microns. On the other hand, the polarizing plate 106 has a thickness of about 300 microns, and there are two glasses having a thickness of 500 to 700 microns, that is, the glass substrate 107 of the liquid crystal panel 101 and the glass substrate 112 of the organic EL element 110. Therefore, the distance between the transmissive opening 104 of the reflective electrode 103 and the organic EL element 110 is 1300 microns to 1700 microns. Therefore, even if the light emitting sections 111 of the organic EL element 110 are installed at positions corresponding to the transmission openings 104, all the light emitted from the light emission sections 111 of the organic EL elements 110 is incident on the transmission openings 104. It is impossible. Therefore, there is still a problem that the irradiation efficiency of the organic EL element 110 is not good.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a display device that is excellent in visibility from outdoors to indoors while achieving downsizing and cost reduction.

  In order to solve the above problems, a display device according to the present invention includes a first display region including a non-light-emitting display element in which a light modulation element reflects external light to display, and a reflective electrode. A light emitting element including a light emitting display element that directly modulates and displays, and includes a first substrate and a second substrate facing each other, and the light modulating element and the light emitting element Are provided between the first substrate and the second substrate, and the light emitting element and the light modulation layer of the light modulation element are sequentially stacked on the first substrate in the second display region. When either one of the first display area and the second display area in the same pixel is in the display state, the other is always in the black state regardless of the presence or absence of external light.

  According to the display device of the present invention, a non-light emitting display element that performs display by reflecting external light and a self-light emitting light emitting display element are incorporated in the same display device. Since it is not necessary to provide a light source, it is possible to realize low power consumption and miniaturization at the same time. In addition, when the non-light-emitting display element and the self-light-emitting light-emitting display element are incorporated in the same display device, the manufacturing process of members such as electrodes, wiring, driving elements, and insulators can be made common. Time and cost required for light source manufacturing and assembly can be greatly reduced.

  Hereinafter, the operation and effect of the present invention will be described in detail.

  First, as described above, the display is generally classified into a non-light emitting display device and a light emitting display device. The non-light emitting display device modulates light transmitted from an external light source such as sunlight, room light, backlight, front light, etc., through a light modulation element that is a non-light emitting display element. There are a reflection type having a reflection means for reflecting light from an external light source and a transmission type having no reflection means. On the other hand, a light-emitting display device is a display device having a light-emitting element. Usually, a portion called a light emitting element or a light emitting layer emits light. Here, control of transmitted light in the light modulation element is referred to as light modulation, whereas light emission from the light emitting element is referred to as direct modulation.

  By the way, in the case of a transmissive non-light emitting display device represented by a transmissive liquid crystal display device, the luminance of the backlight light is usually constant from dark display to bright display and is always lit. Therefore, the transmissive non-light-emitting display device always consumes power from the external light source. In addition, since the transmissive non-light emitting display device requires power supply and control for the light modulation element and the backlight, respectively, the number of parts is large, and there is a limit to downsizing, thereby reducing the cost. It was difficult.

  On the other hand, a light-emitting display device typified by an EL display device modulates light emission luminance, so that power consumption differs between dark display and bright display, and power consumption is small in dark display and large in bright display.

  Here, the present invention is compared with a case where the transmissive non-light emitting display element or the light emitting display element and the reflective non-light emitting display element are incorporated in the same panel and both are used for display. That is, a display device according to the present invention is compared with a conventional display device in which a transmissive non-luminescent display element and a reflective non-luminescent display element are incorporated, that is, a pixel-divided liquid crystal display device described as the prior art. .

  As shown by a broken line L1 in FIG. 2, the conventional liquid crystal display device requires a constant power consumption since it is necessary to always turn on a backlight as a light source from a bright environment to a dark environment. On the other hand, the display device of the present invention in which the light emitting display element and the reflective non-light emitting display element are incorporated in the same panel can display by adjusting the luminance of the light emitting display element in accordance with the surrounding environment. Therefore, as shown by a solid line L2 in FIG. 2, the light emission luminance can be reduced in a bright environment and the reflection type non-light emitting display element can be used to the maximum, while the light emission luminance of the light emitting display element can be increased in a dark environment for display. can do. Therefore, in a bright environment, the power applied to the backlight in the conventional transmissive non-light emitting display device can be kept low.

  Therefore, the display device of the present invention can reduce power consumption and reduce brightness in a bright environment as compared with a display device incorporating a transmissive non-luminescent display element and a reflective non-luminescent display element. By displaying the information, it is possible to realize a longer life and improved reliability. Furthermore, since the display device of the present invention does not require a separate backlight, it can be made thinner and smaller than conventional liquid crystal display devices, and power supply means and control are not required. Therefore, the cost can be reduced.

  FIG. 3 shows a comparison of the display device according to the present invention with a display device having only a light emitting display element. That is, as indicated by a broken line L1 'in FIG. 3, in the case of a display device composed of only light emitting display elements, the display becomes difficult to see unless the light emission luminance is increased as the environment becomes brighter.

  On the other hand, in the display device of the present invention, since the reflective non-light emitting display element improves the display characteristics in a bright environment, the light emitting display element displays with reduced brightness as indicated by a solid line L2 ′ in FIG. It is possible. This is a concept that has not been used in the case of using only a conventional light emitting display element, and is a luminance control method that can be uniquely performed by the configuration of the present invention.

  As described above, according to the display device of the present invention, the maximum luminance can be set lower than that in the case where only the light emitting display element is provided, and a longer life and improved reliability can be realized.

  Specifically, in the display device of the present invention, first, a light emitting element directly modulates a first display area composed of a non-light emitting display element in which a light modulation element reflects external light to display in the display area. A second display area including a light emitting display element for performing display is also provided.

  Therefore, since the light emitting element emits light by itself toward the display surface and directly displays, the light emitting element is not used as a backlight or a front light as in the past. Thereby, the utilization efficiency of light from the light emitting element can be increased, and the thickness of the display device can be reduced. That is, since the thickness of the backlight is usually about 3 to 6 millimeters, the merit of thickness reduction due to the necessity of the backlight is very large. Further, the fact that the backlight is unnecessary means that the polarizing plate, the retardation plate, and the glass substrate that are conventionally installed between the back panel of the liquid crystal panel and the backlight are also unnecessary. Therefore, the thickness of the display device can be further reduced by eliminating the need for the polarizing plate, the retardation plate, and the glass substrate.

  In addition, since it is not necessary to position and fix the patterned light emitting element backlight, it is possible to omit a dedicated device and a fixing mechanism, and it is possible to reduce costs by reducing the number of parts and shortening the process. .

  Furthermore, the advantage that the backlight, the polarizing plate and the retardation plate on the back side are not necessary is not only that the thickness of the entire display device is reduced. In other words, the reduction in the number of members can reduce not only the material cost but also the assembly man-hours and the cost required for inspection of each member, and thus the manufacturing cost of the entire display device can be reduced.

  Further, in a display device of a display area division method such as a pixel division method as in the present invention, the ratio between the first display region and the second display region can be arbitrarily designed to some extent. For this reason, for example, when it is assumed to be used for a mobile device such as a mobile phone or a personal digital assistant (PDA), it is common to increase the ratio of the first display area which is a reflective area. For example, when 80% of the pixel area of the display pixel is used as the reflection region, the second display region, which is the light emitting region, is 20%. Therefore, the light emitting area of the light emitting element is at most one fifth of the pixel area. Just do it. This means that it is possible to reduce power consumption.

  Therefore, it is possible to provide a display device having excellent visibility from the outdoors to the indoors while reducing the size and cost.

  The present invention further includes a first substrate and a second substrate facing each other, and both the light modulation element and the light emitting element are provided between the first substrate and the second substrate. In the second display region, the light emitting element and the light modulation layer of the light modulation element are sequentially stacked on the first substrate. For this reason, since both the light modulation element and the light emitting element are accommodated between the first substrate and the second substrate, the thickness of the display device can be reliably reduced. Further, even if the light modulation layer is laminated on the surface side of the light emitting element, the light emitting element is provided between the first substrate and the second substrate, so that all the display light of the light emitting element is in the second display region. Emitted. Therefore, the light utilization efficiency is very high.

  Therefore, it is possible to provide a display device that can ensure higher irradiation efficiency and reduce not only the brightness but also the thickness of the display device and the member cost.

  Further, when either the first display area or the second display area in the same pixel is in the display state, the other is always in the black state regardless of the presence or absence of external light. For this reason, it is possible to prevent a decrease in contrast caused by driving the light emitting element to emit light.

  The display device of the present invention is characterized in that, in the display device described above, the light-emitting element has an area substantially the same as or smaller than the area of the second display region.

  That is, the light-emitting element is not necessarily formed in the entire second display region, and may be formed in a necessary area according to the required screen luminance. In this regard, in the present invention, the light emitting element has an area that is substantially the same as or smaller than the area of the second display region. Therefore, it is possible to further reduce the power consumption of the light emitting display element.

  The display device of the present invention is characterized in that, in the display device described above, the light emitting element is an organic electroluminescent element.

  For this reason, the light modulation element and the organic electroluminescence element can be easily incorporated between the first substrate and the second substrate.

  In addition, by using a current-driven organic electroluminescence element as the light emitting element, the power consumption of the light emitting element is proportional to the light emitting area. Therefore, the power consumption of the display device according to the present invention is based on the organic electroluminescence element as a backlight. Compared with the case of using, power consumption is, for example, 1/5. Therefore, power consumption can be reliably reduced.

  The display device of the present invention is characterized in that in the display device described above, the light modulation element is a liquid crystal display element.

  According to the above invention, when the light modulation element and the light emitting element are formed in the display region, it is possible to provide a display device having excellent visibility from the outdoors to the indoors while reducing the size and cost.

  The display device of the present invention is characterized in that, in the display device described above, the light emitting element and the light modulation element are driven by sharing a signal line.

  According to the above invention, the light emitting element and the light modulation element are driven by sharing the signal line. Therefore, it is possible to prevent the configuration of the drive circuit of the light emitting element and the light modulation element from becoming complicated, and to provide a display device having excellent visibility from the outdoors to the indoors while surely reducing the size and cost. be able to.

  In the display device of the present invention, the liquid crystal layer that is the light modulation layer of the liquid crystal display element is in the horizontal alignment mode in the first display region and in the vertical alignment mode in the second display region. It is characterized by being.

  As a result, in the state where no voltage is applied to the light modulation element, the first display area is white display, while when the voltage is applied to the light modulation element, the reflectance is zero and the first display area is black display. It becomes.

  Therefore, in the present invention, when the light emitting element and the light modulation element are driven at the same time, the periphery of the second display area which is the display area of the light emitting element is displayed in black, so that the contrast is reduced by driving the light emitting element to emit light. Can be prevented.

  In addition, when the characteristics of the light modulation element are set to the horizontal alignment mode, the pixel electrode for driving the liquid crystal display element is not formed in the second display area where the light emitting element performs display. maintain. Therefore, in a state where the horizontal orientation is maintained, in a place where there is a lot of outside light such as outdoors, the amount of outside light incident on the light emitting element increases. For example, when the light emitting element has a function of a reflector, The reflected light by light increases.

  In this regard, in the present invention, the alignment of the liquid crystal layer stacked on the light emitting element is vertical alignment, and the alignment of the liquid crystal layer in the first display region is horizontal alignment. Therefore, when only the light emitting element emits light without driving the light modulation element, it is possible to prevent a decrease in contrast and an adverse effect on display quality due to superimposition of reflected light of external light in the second display region.

As described above, the display device of the present invention includes a first display region including a non-light-emitting display element in which a light modulation element reflects external light to perform display and a reflective electrode in the display region. And a second display region composed of a light emitting display element that directly modulates and displays,
A first substrate and a second substrate facing each other, wherein the light modulation element and the light emitting element are both provided between the first substrate and the second substrate; and
In the second display area, the light emitting element and the light modulation layer of the light modulation element are sequentially stacked on the first substrate, and either the first display area or the second display area in the same pixel is stacked. Is in a display state, the other is always in a black state regardless of the presence or absence of external light.

  Therefore, since the light emitting element emits light by itself toward the display surface and directly displays the light emitting element, the light emitting element is not used as a backlight or a front light as in the past. Accordingly, the light use efficiency of the light emitting element can be increased and the thickness of the display device can be reduced.

  Further, since the backlight, the polarizing plate, and the retardation plate are not necessary, the number of members is reduced. For this reason, not only the material cost but also the assembly man-hours and the cost required for the inspection of each member can be reduced, so that the manufacturing cost of the entire display device can be reduced. In the pixel division type display device as in the present invention, the ratio between the first display area and the second display area can be arbitrarily designed to some extent. For this reason, for example, when 80% of the pixel area of the display pixel is used as the reflection region, the second display region, which is the light emitting region, is 20%. Therefore, the light emitting area of the light emitting element is at most 5 of the pixel area. One minute is enough.

  Therefore, there is an effect that it is possible to provide a display device with excellent visibility from the outdoors to the indoors while reducing the size and cost.

  Further, when either one of the first display area or the second display area in the same pixel is in the display state, the other is always in a black state regardless of the presence or absence of external light. It is possible to prevent a decrease in contrast caused by driving the element to emit light.

  The display device of the present invention is the display device described above, wherein the light emitting element has an area substantially the same as or smaller than the area of the second display region. Therefore, the power consumption of the light emitting element can be further reduced.

  The display device of the present invention is the display device described above, wherein the light emitting element is an organic electroluminescence element.

  Therefore, the light modulation element and the organic electroluminescence element can be easily incorporated between the first substrate and the second substrate.

  In addition, by using a current-driven organic electroluminescence element as the light emitting element, the power consumption of the light emitting element is proportional to the light emitting area. Therefore, the power consumption of the display device according to the present invention is based on the organic electroluminescence element as a backlight. Compared with the case of using, power consumption is, for example, 1/5. Therefore, there is an effect that power consumption can be surely reduced.

  The display device of the present invention is the above-described display device, wherein the light modulation element is a liquid crystal display element.

  Therefore, when the light modulation element and the light-emitting element are easily formed in the display region, it is possible to provide a display device having excellent visibility from the outdoors to the indoors while reducing the size and cost. Play.

  In the display device of the present invention, the light emitting element and the light modulation element are driven by sharing a signal line.

  Therefore, it is possible to provide a display device that can prevent the configuration of the drive circuit of the light emitting element and the light modulation element from becoming complicated and can surely reduce the thickness of the display device and the member cost. There is an effect.

  In the display device of the present invention, the liquid crystal layer that is the light modulation layer of the liquid crystal display element is in the horizontal alignment mode in the first display region and in the vertical alignment mode in the second display region. There is something.

  Therefore, in a state where no voltage is applied to the light modulation element, the first display area is white display. On the other hand, when a voltage is applied to the light modulation element, the reflectance is zero and the first display area is black display. It becomes.

  Therefore, in the present invention, when the light emitting element and the light modulation element are driven at the same time, the periphery of the second display area which is the display area of the light emitting element is displayed in black, so that the contrast is reduced by driving the light emitting element to emit light. Can be prevented.

  In addition, the alignment of the liquid crystal layer stacked on the light emitting element is vertical alignment, and the alignment of the liquid crystal layer in the first display region is horizontal alignment. Therefore, when only the light emitting element emits light without driving the light modulation element, it is possible to prevent a decrease in contrast and an adverse effect on display quality due to the reflection of the reflected light of the external light in the second display region. There is an effect.

[Embodiment 1]
An embodiment of the present invention will be described with reference to FIGS. 1 and 4 to 10 as follows.

  As shown in FIG. 4, the display device 1 of the present embodiment includes a source bus line 2a as a plurality of data signal lines provided in the vertical direction and a gate bus line as a plurality of scan signal lines provided in the horizontal direction. The display pixels 10 as a display area are formed in a matrix.

  In the present embodiment, the display pixel 10 is divided into a reflective region 11 as a first display region having reflectivity and a transmissive region 12 as a second display region having transparency. That is, as shown in FIG. 1, a pixel electrode 25 made of a metal such as aluminum (Al) constituting the reflective liquid crystal display element 20 as a light modulation element is formed in the reflection region 11. Thus, the external light 4 is reflected by the pixel electrode 25.

  On the other hand, as shown in the figure, a rectangular opening 25 a is formed at the center of the pixel electrode 25, and this opening 25 a serves as the transmission region 12. Below the opening 25a of the pixel electrode 25, that is, behind the pixel electrode 25, an organic EL (Electro Luminescence) light emitting element 40 as a light emitting element is provided via a transparent insulating layer 24. The organic EL light emitting element 40 Displays directly by emitting display light 5 by itself. That is, in the present embodiment, the organic EL light emitting element is not used as a backlight or a front light as in the prior art, but the organic EL light emitting element 40 performs direct display, so the display device of the present embodiment 1 can be said to be a display device in which a reflective liquid crystal display device constituted by the liquid crystal display element 20 and an organic EL (Electro Luminescence) display device constituted by the organic EL light emitting element 40 are integrated.

  Here, the organic EL light emitting element 40 can have an area substantially the same as or smaller than the area of the transmissive region 12. That is, the organic EL light emitting element 40 does not necessarily have to be formed in the entire transmission region 12, but may be formed in a necessary area according to the required screen luminance. For this reason, by making the area of the organic EL light emitting element 40 smaller than that of the transmission region 12, it becomes possible to reduce the power consumption of the organic EL light emitting element 40. Further, the fact that the organic EL light emitting element 40 is substantially the same as the area of the transmissive region 12 means that the organic EL light emitting element 40 may be slightly larger than the area of the transmissive region 12. That is, if the organic EL light emitting device 40 is slightly larger than the area of the transmission region 12, it is considered that the irradiation efficiency of the organic EL light emitting device 40 is not harmed. Even if the organic EL light emitting element 40 is a little larger than the area of the transmissive region 12, there is no problem because the pixel electrode 25 serves as a black matrix risk.

  As shown in the figure, the display device 1 is referred to as a thin film transistor element for liquid crystal (hereinafter, “thin film transistor element”) on an insulating substrate 21 as a first substrate such as a glass substrate. ) 22. As shown in FIG. 4, the liquid crystal TFT element 22 is connected to the gate bus lines 3 and the source bus lines 2a, and functions as a switching element for applying a voltage to the pixel electrode 25 through the drain electrode 22a. . In this embodiment, the liquid crystal TFT element 22 is used as the switching element. However, the present invention is not limited to this, and for example, a liquid crystal MIM (Metal Insulator Metal) element may be used.

  On the other hand, the drain electrode 22a of the liquid crystal display element 20 is a gate electrode of an EL thin film transistor element (hereinafter referred to as "EL TFT element") 42 for driving the organic EL light emitting element 40, as shown in FIG. 42a. Further, a current supply line 2b is connected to the source side of the EL TFT element 42. When the EL TFT element 42 is turned ON, the current supply line 2b and the EL TFT element are supplied by a supply voltage Vdd described later. The organic EL layer 41 emits light when a drive current flows to the organic EL layer 41 of the organic EL light emitting element 40 through the drain electrode 42a. The drive circuits for the liquid crystal display element 20 and the organic EL light emitting element 40 will be described in detail later.

  Here, in order to explain the configuration of the display device 1 in more detail, it will be described below with reference to FIGS.

First, as shown in FIG. 1, a liquid crystal TFT element 22 is formed on an insulating substrate 21 such as a glass substrate. At this time, the EL TFT element 42 is also formed at the same time. Next, after the planarization film 23 is formed to a thickness of 2 μm, for example, with a photosensitive acrylic resin, the reflective anode 43 constituting the organic EL light emitting element 40 is formed to a thickness of 2000 mm with chromium (Cr) by sputtering. To do. Further, silicon dioxide (SiO _{2) is formed} by sputtering. ) Is formed to a thickness of 2000 mm, and the insulating layer 44 is formed by etching so as to have a predetermined shape.

Subsequently, an organic EL layer 41 which is a light emitting layer is formed by a vapor deposition method. The organic EL layer 41 is formed by mask vapor deposition so that red, green, and blue light emitting materials correspond to the respective display pixels 10. Next, in order to inject electrons efficiently into the organic EL layer 41, an alloy (not shown) of magnesium and silver is formed to a thickness of 100 mm by vapor deposition, and then an indium-zinc oxide is formed by sputtering as a transparent cathode 45. (IZO) is formed with a thickness of 2000 mm. Next, tantalum pentoxide (Ta ₂ O ₅ ) is formed as a transparent insulating layer 24 by sputtering to a thickness of 7000 mm, and then a reflective pixel electrode 25 for driving the liquid crystal layer 26 constituting the liquid crystal display element 20. Is formed of aluminum (Al).

  On the other hand, a color filter layer 28 and a counter electrode 27 made of indium tin oxide (ITO) are sequentially formed on an insulating substrate 29 as a transparent second substrate such as the other glass substrate. To do.

  Next, an alignment film (trade name “JALS204 (manufactured by Nippon Synthetic Rubber)”) having the property of aligning liquid crystal molecules perpendicularly to the insulating substrate 29 is applied by spin coating and then baked to form. To do.

  Next, ultraviolet light is irradiated to the molding substrate on the insulating substrate 21 side through a mask (not shown) in which an opening is formed so as to expose only a region other than the portion where the organic EL light emitting element 40 is formed. On the other hand, the ultraviolet light is irradiated to the region other than the portion facing the organic EL light-emitting element 40 when the molded substrate on the insulating substrate 29 side is bonded to the insulating substrate 21. A liquid crystal material having a positive dielectric anisotropy and a Δn of 0.06 after uniaxially aligning an alignment film (not shown) by rubbing these two molded substrates and then bonding them through a seal resin (Merck Co., Ltd.) is injected and the liquid crystal display element 20 is produced. Furthermore, the display device 1 is completed by attaching the retardation film 31 and the polarizing plate 32 in this order to the surface of the insulating substrate 29. In addition, the phase difference of the phase difference plate 31 was set to 1/4 with respect to light with λ = 550 nm.

  When the display device 1 manufactured in this way is observed in a state where no voltage is applied under the external light 4, as shown in FIG. 8 to be described later, the portion located above the organic EL light emitting element 40 is displayed in black. The portion where the organic EL light emitting element 40 is not formed is displayed in white. This is because the liquid crystal molecules are aligned in parallel with the insulating substrate 21 and the insulating substrate 29 by cutting the functional group that expresses the vertical alignment of the alignment film in the portion irradiated with the ultraviolet light.

  As a result, the display mode of the liquid crystal layer 26 is a normally white mode in which white is displayed in a state where no voltage is applied, and black is displayed with the reflectance gradually decreasing with the application of voltage.

  Next, an example of a drive circuit for driving the display device 1 having the above configuration will be described.

  As shown in FIG. 5, in the display device 1, a source driver 6 for sequentially transmitting data line signals is connected to source bus lines 2a, and a gate driver 7 for selecting display pixels 10 is connected to a gate bus line. 3 ... are connected. A display circuit in one display pixel 10 includes a liquid crystal display element 20 that is a light modulation element and an organic EL light emitting element 40 that is a light emitting element.

  The liquid crystal display element 20 and the organic EL light emitting element 40 are arranged in a matrix in the display area of the display device 1, respectively, and the counter electrode 27 of the liquid crystal display element 20, the current supply line 2 b of the EL TFT element 42 and the organic EL element 40. The cathode 45 of the EL light emitting element 40 is connected to each of the liquid crystal display element 20 and the organic EL light emitting element 40 in common. That is, in this drive circuit, the gates that are the signal lines and the scanning signal lines for driving the liquid crystal display element 20 and the organic EL light emitting element 60 in order to actively drive the display pixels 10 as display areas formed in a matrix. The bus lines 3 and the source bus lines 2a, which are signal lines and data signal lines, are shared. However, the present invention is not necessarily limited to this, and can be applied to a simple matrix.

  As shown in FIG. 6, the circuit configuration for one pixel in the display device 1 having the above configuration is such that the gate electrode of the liquid crystal TFT element 22 is connected to the gate bus line 3 and the source bus line 2a is the liquid crystal TFT element 22. Connected to the source electrode. The drain electrode 22 a of the liquid crystal TFT element 22 is connected to the liquid crystal display element 20, the liquid crystal auxiliary capacitor 35, and the gate electrode of the EL TFT element 42. The source electrode of the EL TFT element 42 is connected to the current supply line 2 b, and the drain electrode of the EL TFT element 42 is connected to the anode 43 of the organic EL light emitting element 40. In the above configuration, the organic EL light emitting element 40 is provided on the drain side of the EL TFT element 42. However, the present invention is not limited to this, and for example, as shown in FIG. It can also be provided on the side.

  In the driving circuit of the display device 1 configured as described above, the liquid crystal TFT elements 22 are driven by the scanning line signals from the gate bus lines 3 to switch the signals of the source bus lines 2a. Then, as shown in FIG. 8, when the data line signal Vs is smaller than the EL threshold voltage Vth (OLED) of the EL TFT element 42, the organic EL light emitting element 40 does not emit light and the liquid crystal display element 20 reacts. From bright display to dark display, that is, black display. When the data line signal Vs is larger than the EL threshold voltage Vth (OLED) of the EL TFT element 42, the liquid crystal display element 20 performs dark display. The drain current 42 changes, and the light emission type display is performed by adjusting the light emission amount of the organic EL light emitting element 40. The light emission amount of the organic EL light emitting element 40 can also be adjusted by adjusting the supply voltage Vdd. Further, the display device 1 of the present embodiment is not limited to this driving method, but may be another driving method, but the driving method shown in FIG. 8 is optimal because the driving circuit is common.

  The above display operation will be described in detail with reference to FIGS. 9 to 11 show the state of light when the birefringence when the voltage is not applied to the liquid crystal layer 26 is λ / 4, which is the condition for the highest reflectance.

  First, when the display device 1 is used under the external light 4, when the data line signal Vs is not applied with voltage, or when the drain voltage Vd of the liquid crystal TFT element 22 is equal to or lower than the liquid crystal threshold voltage Vth (LC), As shown in FIG. 9, the external light 4 passes through the polarizing plate 32 and the phase difference plate 31 and then becomes circularly polarized light and enters the liquid crystal layer 26. Next, since the liquid crystal layer 26 has a phase difference of λ / 4, when it reaches the reflective pixel electrode 25, it has a phase difference of λ / 2 and is reflected as linearly polarized light. After the reflection, the external light 4 passes through a path opposite to that at the time of incidence and becomes linearly polarized light, so that it passes through the polarizing plate 32 and becomes white display.

  At this time, since the drain voltage Vd of the liquid crystal TFT element 22 is equal to or lower than the EL threshold voltage Vth (OLED) at which the EL TFT element 42 operates, no current is supplied to the organic EL light emitting element 40 and the non-light emitting state. Become.

  Next, when the display device 1 is used under the external light 4, the black voltage of the liquid crystal display element 20 when the drain voltage Vd of the liquid crystal TFT element 22 is higher than the liquid crystal threshold voltage Vth (LC) is applied. The display will be described.

  As shown in FIG. 10, since the birefringence of the liquid crystal layer 26 is substantially zero, the external light 4 maintains, for example, a right circularly polarized state when reaching the reflective pixel electrode 25. When the light is reflected, for example, it becomes circularly polarized light that is opposite to the left circularly polarized light. For this reason, the reflected light of the external light 4 becomes linearly polarized light having an angle perpendicular to the transmission axis of the polarizing plate 32 after passing through the phase difference plate 31. Therefore, the reflected light of the external light 4 cannot pass through the polarizing plate 32 and the display is black.

  At this time, since the drain voltage Vd of the liquid crystal TFT element 22 is equal to or lower than the EL threshold voltage Vth (OLED) at which the EL TFT element 42 operates, no current is supplied to the organic EL light emitting element 40 and no light emission occurs. The state is maintained.

  Next, the case where the organic EL light emitting element 40 emits light when the intensity of the external light 4 is weak will be described.

  In this case, as shown in FIG. 11, the drain voltage Vd of the liquid crystal TFT element 22 is set to be equal to or higher than the EL threshold voltage Vth (OLED) at which the EL TFT element 42 operates. Thereby, a current is supplied to the organic EL light emitting element 40 to emit light. At this time, as shown in FIG. 5, the drain voltage Vd is sufficiently high, and the liquid crystal layer 26 displays black, so that the light emission of the organic EL light emitting element 40 is not affected.

  Here, in the present embodiment, the anode 43 constituting the organic EL light emitting element 40 is made of a reflective metal and always reflects light regardless of the display signal. For this reason, when an organic EL display is mounted on a product that is frequently used outdoors such as a mobile phone, it is necessary to attach a circularly polarizing plate to the observer side. In this embodiment, as shown in FIG. In addition, the polarizing plate 32 necessary for displaying the liquid crystal layer 26 and the retardation plate 31 having a phase difference of λ / 4 wavelength have a function of making the reflection of the external light 4 almost zero. In addition, the liquid crystal layer 26 exists between the organic EL light emitting element 40 and the polarizing plate 32. In this portion of the liquid crystal layer 26, an electrode such as the counter electrode 27 is formed only on the insulating substrate 29 side. . For this reason, the liquid crystal layer 26 is always in the OFF state regardless of the applied voltage, and does not adversely affect the suppression of reflection of the external light 4.

  In the present embodiment, since the transparent insulating layer 24 is formed so as to cover the entire surface of the organic EL light emitting element 40, the liquid crystal of the liquid crystal layer 26 does not penetrate into the organic EL light emitting element 40 and the liquid crystal Since there is no interference with the display element 20, the reliability of the organic EL light emitting element 40 can be improved.

  As described above, in the display device 1 according to the present embodiment, in each display pixel 10..., The liquid crystal display element 20 reflects the external light 4 and the reflective region 11 including the non-light emitting display element, and the organic EL. A transmissive region 12 made of a light-emitting display element that directly modulates and displays the light-emitting element 40 is also provided.

  Therefore, since the organic EL light emitting element 40 emits light directly toward the display surface and directly displays it, the organic EL light emitting element 40 is not used as a backlight or a front light as in the past. As a result, the light use efficiency of the organic EL light emitting element 40 can be increased, and the thickness of the display device can be reduced. That is, since the thickness of the backlight is usually about 3 to 6 millimeters, the merit of thickness reduction due to the necessity of the backlight is very large. Further, the fact that the backlight is unnecessary means that the polarizing plate, the retardation plate, and the glass substrate that are conventionally installed between the back panel of the liquid crystal panel and the backlight are also unnecessary. Therefore, the thickness of the display device can be further reduced by eliminating the need for the polarizing plate, the retardation plate, and the glass substrate.

  Furthermore, the advantage that the backlight, the polarizing plate and the retardation plate on the back side are not necessary is not only that the thickness of the entire display device is reduced. In other words, the reduction in the number of members can reduce not only the material cost but also the assembly man-hours and the cost required for inspection of each member, and thus the manufacturing cost of the entire display device can be reduced.

  Further, in the pixel division type display device 1 as in the present embodiment, the ratio between the reflective region 11 and the transmissive region 12 can be arbitrarily designed to some extent. For this reason, for example, when it is assumed to be used for a mobile device such as a mobile phone or a personal digital assistant (PDA), it is common to increase the ratio of the reflective region 11. For example, when 80% of the pixel area of the display pixels 10 is the reflective region 11, the transmissive region 12 is 20%. Therefore, the light emitting area of the organic EL light emitting element 40 is at most the pixel area of the display pixel 10. 1/5 of that. This means that it is possible to reduce power consumption.

  Further, in the present embodiment, an insulating substrate 21 and an insulating substrate 29 which are opposed to each other are provided, and both the organic EL light emitting element 40 and the liquid crystal display element 20 are formed of the insulating substrate 21 and the insulating substrate 29. It is provided in between. In the transmissive region 12, the organic EL light emitting element 40 and the liquid crystal layer 26 of the liquid crystal display element 20 are sequentially stacked on the insulating substrate 21. For this reason, since both the liquid crystal display element 20 and the organic EL light emitting element 40 are accommodated between the insulating substrate 21 and the insulating substrate 29, the thickness of the display device 1 can be reliably reduced. Further, even if the liquid crystal layer 26 is laminated on the surface side of the organic EL light emitting element 40, the organic EL light emitting element 40 is provided between the insulating substrate 21 and the insulating substrate 29. All 40 display lights are emitted to the transmission region 12. Therefore, the light utilization efficiency is very high.

  Therefore, it is possible to provide the display device 1 having excellent visibility from the outdoors to the indoors while reducing the size and cost.

  By the way, the organic EL light emitting element 40 does not necessarily have to be formed in the entire transmission region 12, and may be formed in a necessary area according to the required screen luminance. In this regard, in the display device 1 of the present embodiment, the organic EL light emitting element 40 has an area that is substantially the same as or smaller than the area of the transmissive region 12. Therefore, the power consumption of the organic EL light emitting element 40 can be further reduced.

  Further, in the display device 1 of the present embodiment, the light emitting element is composed of the organic EL light emitting element 40. Therefore, the liquid crystal display element 20 and the organic EL light emitting element 40 can be easily incorporated between the pair of insulating substrates 21 and the insulating substrate 29.

  Further, since the power consumption of the light emitting element is proportional to the light emitting area by using the current driven organic EL light emitting element 40 as the light emitting element, the power consumption of the display device 1 of the present embodiment is the organic EL light emitting element. Compared with the case where 40 is used as a backlight, the power consumption is one fifth. Therefore, power consumption can be reliably reduced.

  In the display device 1 of the present embodiment, the light modulation element is the liquid crystal display element 20. Accordingly, when the liquid crystal display element 20 and the organic EL light emitting element 40 are easily formed in one pixel, light is incident on the opening 25a with higher irradiation efficiency, thereby achieving downsizing and cost reduction. It is possible to provide the display device 1 having excellent visibility from the outdoors to the indoors.

  Further, in the display device 1 of the present embodiment, the organic EL light emitting element 40 and the liquid crystal display element 20 are driven by sharing the source bus lines 2a... And the gate bus lines 3. For this reason, it is possible to prevent the configuration of the drive circuit of the organic EL light emitting element 40 and the liquid crystal display element 20 from becoming complicated, and to reliably reduce the thickness of the display device 1 and the member cost. Can be provided.

  By the way, in the present embodiment, when the organic EL light emitting element 40 emits light, for example, when white display is performed, when the liquid crystal display element 20 performs white display, the contrast of one display pixel 10 decreases. To do.

  Therefore, in the present embodiment, the liquid crystal layer 26 of the liquid crystal display element 20 is in the horizontal alignment mode in the reflective region 11 and in the vertical alignment mode in the transmissive region 12. Accordingly, in a state where no voltage is applied to the liquid crystal display element 20, the reflective area 11 is white display, while when a voltage is applied to the liquid crystal display element 20, the reflectance is zero and the reflective area 11 is black. Become.

  Therefore, in the present embodiment, since the periphery of the transmissive region 12 that is the display region of the organic EL light emitting element 40 is displayed in black, it is possible to prevent a decrease in contrast caused by driving the organic EL light emitting element 40 to emit light. .

  Further, in the liquid crystal layer 26 of the liquid crystal display element 20, when the transmissive region 12 in which the organic EL light emitting element 40 performs display is horizontally aligned, the pixel electrode 25 for driving the liquid crystal display element 20 is not formed. The parallel orientation of the initial orientation is maintained. Therefore, especially when this display device 1 is used in a place where there is a lot of outside light 4 such as outdoors, the light reflected by the outside light 4 increases in the transmissive region 12 that maintains the horizontal orientation. That is, the external light 4 is transmitted through the liquid crystal display element 20 and further reflected by the organic EL light emitting element 40.

  In this regard, in the present embodiment, the alignment of the liquid crystal layer 26 stacked on the organic EL light emitting element 40 is a vertical alignment, and the alignment of the liquid crystal layer 26 in the reflective region 11 is a horizontal alignment. Therefore, when only the organic EL light emitting element 40 emits light without driving the liquid crystal display element 20, it prevents the deterioration of contrast and the adverse effect on the display quality due to the reflection of the reflected light of the external light 4 in the transmission region 12. be able to.

  In the present embodiment, the color filter layer 28 formed on the insulating substrate 29 is formed in all the portions facing the reflective region 11 and the transmissive region 12, but the present invention is not limited thereto. The color filter layer 28 does not have to be formed in the portion facing the surface, that is, the region facing the organic EL light emitting element 40. Thereby, the light emitted from the organic EL layer 41 is not absorbed by the color filter layer 28, so that a brighter display is possible. In addition, since the color purity of the organic EL layer 41 is usually superior to the color purity of the color filter layer 28, more colorful display can be performed.

  In the present embodiment, the reflective liquid crystal display element 20 is used as the light modulation element. However, the present invention is not limited to this, and for example, it is possible to display by changing the amount of reflected light using a mirror or the like. A display element may be used. In addition, it is possible to use a reflective light modulation element such as an electrophoretic display, a twist ball display, a reflective display using a fine prism film, a digital mirror device, or the like.

  Further, in the present embodiment, the organic EL light emitting element 40 is used as the light emitting element. However, the present invention is not limited to this. For example, an inorganic EL light emitting element, an LED (Light Emitting Diode) or the like is an element having variable light emission luminance. Applicable if possible. Further, a light emitting element such as a field emission display (FED) or a plasma display can be used.

[Embodiment 2]
The following will describe another embodiment of the present invention with reference to FIGS. For convenience of explanation, members having the same functions as those shown in the drawings of the first embodiment are given the same reference numerals, and descriptions thereof are omitted.

  In the present embodiment, a case where the liquid crystal display element 20 and the organic EL light emitting element 40 are driven simultaneously will be described. The driving here does not indicate a state in which a voltage is simply applied to the liquid crystal display element 20 or a current is simply flowing in the organic EL light emitting element 40, but according to information displayed by the voltage or current. Is controlled, and the reflected light intensity or the light emission intensity of the light emitting element is changed to display.

  In this embodiment, when the display device 1 is manufactured, an alignment film (not shown) having the property of aligning the liquid crystal molecules shown in FIG. 1 perpendicularly to the insulating substrate 29 (trade name “JALS204 (manufactured by Nippon Synthetic Rubber Co., Ltd.). ) ”), And after orientation treatment by rubbing, two molded substrates, a molded substrate on the insulating substrate 29 side and a molded substrate on the insulating substrate 21 side, are bonded via a sealing resin (not shown). In addition, a liquid crystal material having a negative dielectric anisotropy (trade name “MLC6608 (manufactured by Merck))” is injected as the liquid crystal layer 26 to produce the liquid crystal display element 20. Further, the retardation plate 31 and the polarizing plate 32 are sequentially attached to the surface of the insulating substrate 29 to complete the display device 1. Also in the present embodiment, the retardation plate 31 has a phase difference of 1/4 with respect to light of λ = 550 nm.

  In the present embodiment, a drive circuit different from that in the first embodiment is used as the drive circuit. That is, in the present embodiment, the liquid crystal display element 20 and the organic EL light emitting element 40 are driven independently of each other.

  A specific display operation of the display device 1 having the above configuration will be described with reference to FIGS.

  First, as shown in FIG. 12, the display mode of the liquid crystal layer 26 uses, as described above, the liquid crystal layer 26 made of a liquid crystal material having a negative dielectric anisotropy and an alignment film (not shown) having a vertical alignment property. Therefore, while displaying black in a state where no voltage is applied, as shown in FIG. 13, a normally black mode is performed in which the reflectance gradually increases with voltage application and white display is performed.

  That is, when the display device 1 is used under the external light 4, when no voltage is applied or the drain voltage Vd is equal to or less than the common threshold voltage Vth, the external light 4 is transmitted through the polarizing plate 32 and the retardation plate as shown in FIG. After passing through 31, it becomes circularly polarized light and enters the liquid crystal layer 26. When the drain voltage Vd equal to or lower than the common threshold voltage Vth is applied to the liquid crystal layer 26 by the liquid crystal TFT element 22, the birefringence of the liquid crystal layer 26 is 0, so when the pixel electrode 25 reaches the reflective pixel electrode 25, for example, Although the circularly polarized state of the right circularly polarized light is maintained, when it is reflected by the pixel electrode 25, for example, the circularly polarized light is reverse to the left circularly polarized light. For this reason, the reflected light becomes linearly polarized light at an angle orthogonal to the transmission axis of the polarizing plate 32 after passing through the retardation plate 31. Thereby, the reflected light of the external light 4 cannot pass through the polarizing plate 32 and the display is black. Accordingly, as shown in FIG. 14A, the luminance of the liquid crystal display element 20 is substantially zero. At this time, as shown in FIG. 14B, the organic EL light emitting element 40 is also in the OFF state because it is equal to or lower than the common threshold voltage Vth, and no current is supplied to the organic EL layer 41 so that it does not emit light. It becomes.

  Next, a case where white display is performed by applying a voltage will be described with reference to FIG. In the figure, the state of light with a birefringence of λ / 4 of the liquid crystal layer 26, which is the condition for the highest reflectance, is shown.

  As shown in FIG. 13, when a drain voltage Vd equal to or higher than the common threshold voltage Vth is applied to the liquid crystal layer 26, the liquid crystal layer 26 has birefringence and cannot maintain a circularly polarized state. Therefore, the reflected light of the external light 4 from the reflective pixel electrode 25 is transmitted through the polarizing plate 32, and the luminance display of the liquid crystal display element 20 is white as shown in FIG.

  At this time, as shown in FIG. 13, since the EL TFT element 42 is also in the ON state, the current supplied from the current supply line 2b causes the organic EL light emitting element 40 to appear as shown in FIG. The light emission state is activated.

  Here, as shown in FIG. 1, the anode 43 constituting the organic EL light emitting element 40 is made of a reflective metal and always reflects light regardless of the display signal. Therefore, when an organic EL display is mounted on a product that is frequently used outdoors such as a mobile phone, it is necessary to attach a circularly polarizing plate to the viewer side. In the present embodiment, the display of the liquid crystal layer 26 is required. The polarizing plate 32 and the retardation plate 31 having a phase difference of λ / 4 wavelength have a function of making the reflection of the external light 4 almost zero.

  In addition, a liquid crystal layer 26 exists between the organic EL light emitting element 40 and the polarizing plate 32, and an electrode is disposed on the insulating substrate 29 side like the counter electrode 27 in the liquid crystal layer 26 portion of the transmission region 12. Only formed. For this reason, as shown in FIGS. 12 and 13, the liquid crystal layer 26 is always in the OFF state regardless of the applied voltage, and maintains the vertical alignment, so that it does not adversely affect the suppression of reflection of the external light 4.

  In the present embodiment, the example in which the liquid crystal layer 26 and the organic EL light emitting element 40 are driven simultaneously has been described. However, when the external light 4 is strong, the current supply to the organic EL light emitting element 40 is stopped. It is also possible to reduce power consumption by displaying only the liquid crystal layer 26.

  Also in the present embodiment, as in the first embodiment, since the transparent insulating layer 24 is formed so as to cover the entire surface of the organic EL light emitting device 40, the liquid crystal of the liquid crystal layer 26 is the organic EL light emitting device. Since it does not penetrate into the liquid crystal display 40 and does not interfere with the liquid crystal display element 20, the reliability of the organic EL light emitting element 40 can be improved.

  Thus, in the display device 1 of the present embodiment, the organic EL light emitting element 40 and the liquid crystal display element 20 are driven independently of each other. For this reason, it becomes possible to drive the organic EL light emitting element 40 and the liquid crystal display element 20 individually. In addition, as a structure for driving the organic EL light emitting element 40 and the liquid crystal display element 20 independently of each other, for example, the organic EL light emitting element 40 and the liquid crystal display element 20 include the source bus line 2a. .. May be provided, or the source bus lines 2a may be provided respectively, but the gate bus lines 3 may be shared.

  In the display device 1 of the present embodiment, the liquid crystal display element 20 is normally black. Therefore, when the liquid crystal display element 20 and the organic EL light emitting element 40 are driven independently, when only the organic EL light emitting element 40 is driven without driving the liquid crystal display element 20, the display of the organic EL light emitting element 40 is performed. The area around the transmissive area 12 is a black display that does not reflect light.

  Accordingly, it is possible to prevent a decrease in contrast when only the organic EL light emitting element 40 is driven to emit light.

  In addition, in this Embodiment, it has the structure and function similar to Embodiment 1 except the structure in which the liquid crystal display element 20 is normally black.

FIG. 5 shows an embodiment of a display device according to the present invention and is a cross-sectional view taken along line AA of FIG. 4 showing one pixel in the display device. It is a graph which shows the concept of this invention and shows the relationship between a display environment and power consumption. It is a graph which shows the concept of this invention and shows the relationship between a display environment and a brightness | luminance. It is a top view which shows 1 pixel in the said display apparatus. It is a whole block diagram which shows the said display apparatus. FIG. 3 is a drive circuit diagram illustrating one pixel of the display device. FIG. 10 is another drive circuit diagram showing one pixel of the display device. It is a signal waveform diagram at the time of driving of the display device. When the said display apparatus is a normally white mode, it is explanatory drawing which shows the display state of a liquid crystal display element and an organic electroluminescent light emitting element in case the drain voltage Vd is smaller than the threshold voltage Vth (LC) for liquid crystals. Liquid crystal display element and organic EL light emitting element when drain voltage Vd is larger than liquid crystal threshold voltage Vth (LC) and smaller than EL threshold voltage Vth (OLED) when the display device is in a normally white mode It is explanatory drawing which shows the display state of. Liquid crystal display element and organic EL light emitting element when drain voltage Vd is larger than liquid crystal threshold voltage Vth (LC) and larger than EL threshold voltage Vth (OLED) when the display device is in a normally white mode It is explanatory drawing which shows the display state of. When the display device is in a normally black mode, the display state of the liquid crystal display element and the organic EL light emitting element when the drain voltage Vd is smaller than the common threshold voltage Vth is an explanatory diagram. When the said display apparatus is normally black mode, it is explanatory drawing which shows the display state of a liquid crystal display element and an organic electroluminescent light emitting element in case drain voltage Vd is larger than shared threshold voltage Vth. (A) is explanatory drawing which shows the luminance state of the liquid crystal display element in case a display apparatus is normally black mode, (b) is the luminance state of the organic EL light emitting element in case a display apparatus is normally black mode. It is explanatory drawing which shows. It is sectional drawing which shows the conventional display apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Display apparatus 2a Source bus line 2b Current supply line 3 Gate bus line 4 External light 5 Display light 6 Source driver 7 Gate driver 10 Display pixel (display area)
11 Reflection area (first display area)
12 Transmission area (second display area)
20 Liquid crystal display elements (light modulation elements)
21 Insulating substrate (first substrate)
22 TFT element for liquid crystal 22a Drain electrode 24 Transparent insulating layer 25 Pixel electrode 25a Opening 26 Liquid crystal layer 27 Counter electrode 29 Insulating substrate (second substrate)
31 Phase difference plate 32 Polarizing plate 40 Organic EL light emitting device (light emitting device, organic electroluminescence device)
42 EL TFT element Vdd Supply voltage Vth Shared threshold voltage Vth (LC) Liquid crystal threshold voltage Vth (OLED) EL threshold voltage Vs Data line signal

Claims (7)

A first display region composed of a non-light-emitting display element that performs display by reflecting light from the outside in the same pixel in the display region, and light emission that is directly modulated by a light-emitting element that includes a reflective electrode. And a second display area made up of display elements,
A first substrate and a second substrate facing each other, wherein the light modulation element and the light emitting element are both provided between the first substrate and the second substrate; and
In the second display area, the light emitting element and the light modulation layer of the light modulation element are sequentially stacked on the first substrate,
The display device according to claim 1, wherein when one of the first display area and the second display area in the same pixel is in a display state, the other is always in a black state regardless of the presence or absence of external light.   The display device according to claim 1, wherein the light modulation element in the second display region is formed on the light emitting element via a transparent insulating layer.   The display device according to claim 1, wherein the light emitting element has an area substantially equal to or smaller than an area of the second display region.   The display device according to claim 1, wherein the light emitting element is an organic electroluminescence element.   The display device according to claim 1, wherein the light modulation element is a liquid crystal display element.   The display device according to claim 1, wherein the light emitting element and the light modulation element are driven by sharing a signal line.   The light modulation element is a liquid crystal display element, and the liquid crystal layer which is a light modulation layer of the liquid crystal display element is in a horizontal alignment mode in the first display area and in a vertical alignment mode in the second display area. The display device according to claim 1.

Images