Electroluminescent display device

This invention is based on Japanese Patent Application No. 2003-411617, the content of which is incorporated by reference in its entirety.

1. Field of the Invention

This invention relates to an electroluminescent display device, particularly to such a device having a touch panel function.

2. Description of the Related Art

In recent years, organic electroluminescent (hereafter, referred to as EL) display devices using EL elements have been receiving attention as a display device substituting for a CRT or an LCD. Particularly, an organic EL display device having thin film transistors (hereafter, referred to as TFTs) as switching elements for driving the organic EL elements has been developed.

The LCD has a wide range of applications, for example, from displays for cellular phones and to those for personal digital assistants. Furthermore, a touch panel used with a finger or a pen-type pointing device has been developed.

Such technologies are described in Japanese Patent Application Publication Nos. 2002-175029 and 2002-214583. However, the organic EL display device has not been applied to touch panels used with the finger or the pen-type pointing device.

This invention provides an organic EL display device having a touch panel function, and is directed to improving accuracy in positional detection on a display portion of such an organic EL display device.

The invention provides an electroluminescent display device that includes a display portion having a plurality of display pixels arranged in a matrix. Each of the pixels has a display electroluminescent element and a driving transistor driving the display electroluminescent element. The device also includes a light source portion having a plurality of light source electroluminescent elements and provided along a first side of the display portion and a light detecting portion having a plurality of light sensors and provided along a second side of the display portion. The second side is opposite from the first side. The device further includes a first reflecting board reflecting light emitted by the light source portion in a horizontal direction along a front surface of the display portion and a second reflecting board reflecting the light reflected by the first reflecting board so as to lead the light into the light detecting portion through a back surface of the display portion.

FIG. 1A is a plan view of an organic EL display device of a first embodiment of the invention, FIG. 1B is a schematic cross-sectional view of FIG. 1A along line A—A, and FIG. 1C is a schematic cross-sectional view of FIG. 1A along line B—B.

FIGS. 2A , 2 B, and 2 C are schematic plan views of a display panel showing an operation of the organic EL display device of FIGS. 1A , 1 B, and 1 C.

FIG. 3 is an equivalent circuit diagram of a display pixel of the organic EL display device of the first embodiment of the invention.

FIG. 4 is a schematic cross-sectional view of a display organic EL element and a light sensor of the first embodiment of the invention.

FIGS. 5A and 5B are schematic cross-sectional views of an organic EL display device of a second embodiment along line A—A and line B—B in the plan view, respectively.

FIG. 6 is a schematic cross-sectional view of a display organic EL element and a light sensor of the second embodiment of the invention.

FIG. 1A is a plan view of the organic EL display device of a first embodiment of the invention. In this embodiment, a plurality of display pixels PEL (shown in FIG. 4 ) is arrayed in a matrix in a display portion 10 of a display panel 1 . Each of the display pixels PEL has a display organic EL element 11 A (e.g. top emission type organic EL element), a pixel selecting TFT (e.g. top gate type TFT) (not shown) selecting the display pixel PEL, a driving TFT 61 A (e.g. top gate type TFT) driving the display organic EL element 11 A, and so on.

As shown in FIG. 1A , the display portion 10 is shaped in a rectangle in the plan view. A first side and a second side of the display portion 10 in the plan view respectively correspond to an x coordinate and a y coordinate of a rectangular coordinate system formed of x and y axes. A light source portion 20 x is placed along the side on the x axis. A plurality of light source organic EL elements 21 A (e.g. top emission type organic EL element) is aligned in the light source portion 20 x . Furthermore, a light detecting portion 30 x is provided along a side opposite from the light source portion 20 x . A plurality of light sensors 31 A (e.g. top gate type TFT) is aligned in the light detecting portion 30 x . The light sensor 31 A generates a predetermined current or voltage when receiving light, and the current or the voltage is electrically detected so that the light can be detected.

Similarly, a light source portion 20 y is placed along a side on a y-axis of the display portion 10 . A plurality of light source organic EL elements 21 A (e.g. top emission type organic EL element) is aligned in the light source portion 20 y . A light detecting portion 30 y is provided along a side opposite from the light source portion 20 y . A plurality of light sensors 31 A (e.g. top gate type TFT) is aligned in the light detecting portion 30 y.

Next, a structure of a display panel 1 will be described with reference to a cross-sectional view thereof. FIG. 1B is a schematic cross-sectional view of FIG. 1A along line A—A, and FIG. 1C is a schematic cross-sectional view of FIG. 1A along line B—B.

As shown in FIGS. 1B and 1C , the display portion 10 , the light source portions 20 x and 20 y , and the light detecting portions 30 x and 30 y are provided on the same transparent glass substrate 40 A, being integrally formed as a display panel 1 . The light source organic EL elements 21 A of the light source portions 20 x and 20 y have the same structure (a structure of a top emission type organic EL element outputting light toward the direction opposite from the transparent glass substrate 40 A) as that of the display organic EL elements 11 A of the display portion 10 so that the light source organic EL elements 21 A and the display organic EL elements 11 A are formed by the same manufacturing steps. Furthermore, the light sensors 31 A of the light detecting portions 30 x and 30 y can be formed of TFTs so that the light sensors 31 A can be formed by the same manufacturing steps as the steps for manufacturing the pixel selecting TFTs and the driving TFTs 61 A in the display portion 10 . This reduces the number of components in the organic EL display device, preventing complexity of manufacturing steps.

This display panel 1 is placed in a container 50 , and the display portion 10 is exposed through a window of the container 50 . This display panel 1 is thus configured to emit display light of the display portion 10 .

A light reflecting board 51 x for reflecting light is provided above the light source portion 20 x inside the container 50 along a side of an x-axis of the display portion 10 . The light reflecting board 51 x reflects light, which is emitted in a vertical direction through a front surface of the display panel 1 from the light source organic EL element 21 A of the light source portion 20 x , in a horizontal direction along the front surface of the display panel 1 .

Furthermore, near the light detecting portion 30 x inside the container 50 , a reflecting board 52 x is provided so as to cover an edge portion of the display panel 1 , which contains the light sensors 31 A, as shown in FIG. 1B .

an upper side and a lower side of the light detecting portion 30 x from the side. The reflecting board 52 x is formed having three reflecting surfaces A, B, and C having predetermined reflecting angles. This reflecting board 52 x reflects light, which is incident horizontally along the front surface of the display panel 1 , in a vertical direction (toward backside direction of the light detecting portion 30 x ) by the reflecting surface A above the light detecting portion 30 x. Furthermore, this reflected light is reflected in a horizontal direction along the back surface of the display panel 1 and then in a vertical direction (toward the front side direction of the light detecting portion 30 x ) by the reflecting surface B and the reflecting surface C respectively, which are a part of the reflecting board 52 x placed below the light detecting portion 30 x . In this embodiment, all the reflecting angles are different.

When the light, which is emitted by the light source portion 20 x and reflected in a horizontal direction along the front surface of the display panel 1 by the reflecting board 51 x, is not blocked by a pointing object (not shown) such as a pen or a finger which touches or is placed close to the display portion 10 , the light is further reflected by the light reflecting board 52 x and enters the first light detecting portion 30 x through the back surface of the display panel 1 . The reflecting board 52 x is formed inside the container 50 which no external light enters, and each of the reflecting surfaces has such a predetermined reflecting angle that only light reflected in a horizontal direction along the front surface of the display panel 1 can enter the light detecting portion 30 x . Therefore, external light incident at an angle different from the angle of the horizontal front surface of the display panel 1 does not enter the light detecting portion 30 x.

Similarly, a light reflecting board 51 y for reflecting light is provided above the light source portion 20 y inside the container 50 along a side of a y-axis of the display portion 10 . The light reflecting board 51 y reflects light, which is emitted in a vertical direction through the front surface of the display panel 1 from the light source organic EL element 21 A of the light source portion 20 y , in a horizontal direction along the front surface of the display panel 1 .

Furthermore, near the light detecting portion 30 y inside the container 50 , a reflecting board 52 y is provided so as to cover the edge of the display portion 1 . The reflecting board 52 y has three reflecting surfaces D, E, and F having predetermined reflecting angles. This reflecting board 52 y reflects light, which is incident horizontally along the front surface of the display panel 1 , in the vertical direction by the reflecting surface D above the light detecting portion 30 y . Furthermore, this reflected light is reflected in the horizontal direction along the back surface of the display panel 1 and then in a vertical direction by the reflecting surface E and the reflecting surface F respectively, which are a part of the reflecting board 52 y placed below the light detecting portion 30 y.

When the light, which is emitted by the light source portion 20 y and reflected in the horizontal direction along the front surface of the display panel 1 by the reflecting board 51 y, is not blocked by a pointing object such as a pen or a finger which touches or is placed close to the display portion 10 , the light is further reflected by the light reflecting board 52 y and enters the light detecting portion 30 y through the back surface of the display panel 1 . The reflecting board 52 y is formed inside the container 50 which no external light enters, and each of the reflecting surfaces has such a predetermined reflecting angle that only light reflected in a horizontal direction along the front surface of the display panel 1 can enter the light detecting portion 30 y . Therefore, external light incident at an angle different from the angle of the horizontal front surface of the display panel 1 does not enter the light detecting portion 30 y.

Next, a detection process of a point P corresponding to a position where the pointing object such as a pen or a finger touches or is placed close to the display portion 10 will be described with reference to FIGS. 1A , 1 B, and 1 C. The coordinates (x, y) of this point P are determined as follows. Assume that the x coordinate corresponds to the first side of the display portion 10 , and the y coordinate corresponds to the second side of the display portion 10 . Furthermore, light emitted from each of the light source organic EL elements 21 A of the light source portions 20 x and 20 y has directivity similar to those of laser beams.

First, the x coordinate of the point P is determined as described below. Light emitted in a vertical direction through the front surface of the display panel 1 from the light source organic EL element 21 A of the light source potion 20 x is reflected in a horizontal direction along the front surface of the display panel 1 by the reflecting board 51 x . The light reflected in a horizontal direction along the front surface of the display panel 1 is reflected in the vertical direction relative to the front surface of the display panel 1 by the reflecting surface A formed in the reflecting board 52 x above the light detecting portion 30 x , when the light is not blocked by the pointing object touching or placed close to the display portion 10 . This reflected light is reflected in a horizontal direction again by the reflecting surface B of the reflecting board 52 x below the light detecting portion 30 x . Then, the light is reflected in the vertical direction by the reflecting surface C.

Therefore, the light emitted from the light source portion 20 x enters the light detecting portion 30 x through a backside of the display panel 1 and is detected by the corresponding light sensor 31 A, when the light is not blocked by the pointing object. On the other hand, when the pointing object touches or is placed close to the display portion 10 , the light emitted from the light source portion 20 x is blocked by the pointing object, so that the light sensor 31 A corresponding to this position does not detect the light. Therefore, the position of this light sensor 31 A which does not detect the light corresponds to the x coordinate of the point P on the display portion 10 .

The reflecting board 52 x is formed inside the container 50 which no external light enters, and each of the reflecting surfaces A, B, and C has such a predetermined reflecting angle that only light reflected in the horizontal direction along the front surface of the display panel 1 can enter the light detecting portion 30 x . Therefore, external light incident at an angle different from the angle of the horizontal front surface of the display panel 1 is not detected by the light sensor 31 A of the light detecting portion 30 x. This can reduce detection errors caused by external light, and improve accuracy in detection of the x coordinate of the point P.

Similarly, the y coordinate of the point P is determined as described below. Light emitted in a vertical direction through the front surface of the display panel 1 from the light source organic EL element 21 A of the light source potion 20 y is reflected in a horizontal direction along the front surface of the display panel 1 by the reflecting board 51 y. The light reflected in a horizontal direction along the front surface of the display panel 1 is reflected in the vertical direction relative to the front surface of the display panel 1 by the reflecting surface D formed in the reflecting board 52 y above the light detecting portion 30 y , when the light is not blocked by the pointing object touching or placed close to the display portion 10 . This reflected light is reflected in a horizontal direction again by the reflecting surface E of the reflecting board 52 y below the light detecting portion 30 y . Then, the light is reflected in the vertical direction by the reflecting surface F.

Therefore, the light emitted from the light source portion 20 y enters the light detecting portion 30 y through the back surface of the display panel 1 and is detected by the corresponding light sensor 31 A, when the light is not blocked by the pointing object. On the other hand, when the pointing object touches or is placed close to the display portion 10 , the light emitted from the light source portion 20 y is blocked by the pointing object, so that the light sensor 31 A corresponding to this position does not detect the light. Therefore, the position of this light sensor 31 A which does not detect the light corresponds to the y coordinate of the point P on the display portion 10 .

The reflecting board 52 y is formed inside the container 50 which no external light enters, and each of the reflecting surfaces D, E, and F has such a predetermined reflecting angle that only light reflected in the horizontal direction along the front surface of the display panel 1 can enter the light detecting portion 30 y . Therefore, external light incident at an angle different from the angle of the horizontal surface of the display panel 1 is not detected by the light sensor 31 A of the light detecting portion 30 y . This can reduce detection errors caused by external light, and improve accuracy in detection of the y coordinate of the point P.

When light emitted from each of the light source organic EL elements 21 A of the light source portions 20 x and 20 y does not have directivity similar to those of laser beams, the x and y coordinates of the point P (x, y) can be determined as described below.

That is, the x and y coordinates of the point P (x, y) are determined by sequentially switching the light source organic EL elements for emitting light, and by monitoring the positions of the light sensors which do not detect the light each time. A process of determining the x and y coordinates of the point P (x, y) in this case will be described with reference to FIGS. 2A , 2 B, and 2 C.

FIGS. 2A , 2 B, and 2 C are schematic plan views of the display panel 1 explaining an example of the process of determining the x and y coordinates of the point P (x, y) under the divergent light source. In FIGS. 2A , 2 B and 2 C, the numbers of the light source organic EL elements and the light sensors are smaller than the numbers shown in FIG. 1A for simplifying description.

As shown in FIG. 2A , light is emitted in the vertical direction through a transparent glass substrate 40 A (not shown) from a light source organic EL element 21 a provided in one end of the first light source portion 20 x . This light is reflected in the horizontal direction along the transparent glass substrate 40 A by the light reflecting board 51 x (not shown) provided above the light source portion 20 x . In a position where the light reflected in the horizontal direction is not blocked by the pointing object PT, the light is then reflected in the backside direction of the display panel 1 by the light reflecting board 52 x (not shown) provided above the light detecting portion 30 x to enter the light detecting portion 30 x . Furthermore, the light is reflected in the backside direction of the display panel 1 by the light reflecting board 52 y (not shown) provided above the light detecting portion 30 y to enter the light detecting portion 30 y.

The light entering the light detecting portions 30 x and 30 y is detected by the light sensors corresponding to positions where the light enters (light sensors 31 a, 31 d, 31 e, 31 f, 31 g, 31 h, 31 i, and 31 j in an example of FIG. 2A ).

On the other hand, where the light reflected in a horizontal direction is blocked by the pointing object PT, the light does not enter the light detecting portions 30 x and 30 y . That is, the light sensors (light sensors 31 b and 31 c in an example of FIG. 2A ) corresponding to the positions where the light does not enter do not detect the light.

Accordingly, the light sensors which do not detect the light are searched among the light sensors of the light detecting portions 30 x and 30 y , and x coordinates or y coordinates of those light sensors are stored in a storage medium (not shown) such as a memory. When this operation is completed, the light source organic EL element 21 a is turned off the light.

Next, as shown in FIG. 2B , light is emitted from a light source organic EL element 21 b adjacent the light source organic EL element 21 a. Then, x coordinates or y coordinates of the light sensors (light sensors 31 a and 31 b in an example of FIG. 2B ) which do not detect the light 20 among the light sensors of the light detecting portions 30 x and 30 y are stored in the memory (not shown) and so on. When this operation is completed, the light source organic EL element 21 b is turned off the light.

Similarly, light source organic EL elements 21 c, 21 d, 21 e and 21 f placed adjacent each other in the light source portion 20 x are sequentially switched to emit light and turn off the light. The light sensors which do not detect the light are searched each time, and x coordinates or y coordinates of the light sensors are stored in the memory (not shown) and so on. As shown in FIG. 2C , when light is emitted from the light source organic EL element 21 f, an x coordinate or a y coordinate of the light sensor (light sensor 31 j in an example of FIG. 2C ) which does not detect the light is stored in the memory (not shown) and so on.

After a sequence of light emission and turn-off is completed from the light source organic EL element 21 a provided on one end of the light source portion 20 x to the light source organic EL element 21 f provided on another end thereof, the light emission and turn-off in the light source portion 20 y are sequentially performed from the light source organic EL element 21 g provided on one end thereof to the light source organic EL element 21 j provided on another end thereof. At each operation, the light sensors which do not detect the light are searched in the light detecting portions 30 x and 30 y , and x or y coordinates corresponding to the light sensors are monitored and stored in the memory and so on (not shown).

As described above, the light sensors of the light detecting portions 30 x and 30 y , which do not detect the light emitted from the light source portions 20 x and 20 y , are searched. The x coordinate or the y coordinate corresponding to each of the detected light sensors is monitored each time, and stored in the memory (not shown) and so on.

Then, the x or y coordinates of the light sensors which do not detect the light, which are monitored and stored each time, are all used to determine the x and y coordinates of the point P (x, y) representing the location of the pointing object PT that touches or is placed close to the display portion 10 . Then, the data stored in the memory and so on are initialized for next detection of the point P (x, y).

Next, a structure of a display pixel PEL having the display organic EL element 11 A and so on will be described in detail with reference to drawings. FIG. 3 shows an equivalent circuit diagram of the display pixels PEL disposed in a matrix on the display portion 10 . It is noted that FIG. 3 shows one display pixel PEL only.

A gate signal line L 1 supplying a gate signal Gn for selecting the display pixels PEL and a drain signal line L 2 supplying a display signal Dm for each of the display pixels PEL are crossing each other in the display pixel PEL. An organic EL element 11 A serving as a self-emissive element, a driving TFT 61 A for supplying a current to the organic EL element 11 A, and a pixel selecting TFT 71 A for selecting the display pixel PEL are disposed in a region enclosed with these signal lines.

A gate of the pixel selecting TFT 71 A is connected with the gate signal line L 1 and supplied with the gate signal Gn therefrom, and a drain 71 A d of the pixel selecting TFT 71 A is connected with the drain signal line L 2 and supplied with the display signal Dm therefrom. A source 71 A s of the pixel selecting TFT 71 A is connected with a gate of the driving TFT 61 A. A source 61 A s of the driving TFT 61 A is supplied with a positive power supply voltage PVdd from a power supply line L 3 . A drain 61 A d of the driving TFT 61 A is connected with an anode 12 A of the organic EL element 11 A. A transparent cathode 14 A of the organic EL element 11 A is supplied with a power supply voltage CV.

The gate signal Gn is outputted from a vertical driver circuit (not shown) for switching the display pixel PEL in a vertical direction. The display signal Dm is outputted from a horizontal driver circuit (not shown) for controlling displays of the display pixels PEL arrayed in a horizontal direction.

The gate of the driving TFT 61 A is connected with a storage capacitor Cs. The storage capacitor Cs is provided to store the display signal Dm to be supplied to the display pixel PEL for a field period by storing electric charge corresponding to the display signal Dm.

The display pixel PEL described above is operated as follows. When the gate signal Gn becomes high level for one horizontal period, the pixel selecting TFT 71 A turns on. Then, the display signal Dm is applied from the drain signal line L 2 to the gate of the driving TFT 61 A through the pixel selecting TFT 71 A. Conductance of the driving TFT 61 A changes in accordance with the display signal Dm supplied to the gate thereof, and a drive current in accordance with the conductance is supplied to the organic EL element 11 A through the driving TFT 61 A, thereby lighting the organic EL element 11 A. When the driving TFT 61 A turns off in accordance with the display signal Dm supplied to the gate, an electric current does not flow in the driving TFT 61 A, thereby turning off the light of the organic EL element 11 A.

Next, structures of the display organic EL element 11 A, the driving TFT 61 A, and the light sensor 31 A of the display pixel PEL will be described with reference to a schematic cross-sectional view in detail.

FIG. 4 is a schematic cross-sectional view of the display organic EL element 11 A and the driving TFT 61 A of the display pixel PEL, and the light sensor 31 A of the light detecting portions 30 x and 30 y and its neighborhood. FIG. 4 shows one of the display pixels PEL arrayed in a matrix on the display portion 10 . The display organic EL element 11 A of the display pixel PEL is of top emission type, and the driving TFT 61 A for driving the display organic EL element 11 A is of top gate type. Although not shown, the pixel selecting TFT 71 A is of top gate type like the driving TFT 61 A. The light sensor 31 A is formed of a top gate type TFT.

These display organic EL element 11 A, the driving TFT 61 A, the pixel selecting TFT 71 A, and the light sensor 31 A are disposed on the same glass substrate 40 A. A configuration of these elements will be described in detail hereafter.

A buffer layer BF formed by laminating, for example, SiN x and SiO 2 in this order, an active layer 62 A formed by poly-crystallizing an a-Si film by laser beam irradiation, a gate insulating film 63 A, and a gate electrode 64 A made of metal having a high melting point such as chromium or molybdenum are formed on the transparent glass substrate 40 A, in this order. A channel 62 Ac, a source 62 As, and a drain 62 Ad are provided in the active layer 62 A, the source 62 As and the drain 62 Ad being disposed on sides of the channel 62 Ac respectively.

An interlayer insulating film 65 A laminated with an SiO 2 film, an SiN x film, and an SiO 2 film in this order is formed on the whole surfaces of the gate insulating film 63 A and the gate electrode 64 A. A contact hole C 1 is provided in the interlayer insulating film 65 A in a position corresponding to the source 62 As, and the power supply line L 3 to be supplied with a positive power supply voltage PVdd is provided therein by filling metal such as Al therein.

A contact hole C 2 is provided in the interlayer insulating film 65 A in a position corresponding to the drain 62 Ad, and a drain electrode 3 d is provided therein by filling the hole with a metal such as Al therein. Furthermore, a planarization insulating film 66 A made of, for example, organic resin and planarizing a surface is provided on the whole surface. A contact hole C 3 is provided in the planarization insulting film 66 A in a position corresponding to the drain electrode 3 d, and metal such as Al fills the hole so that the drain electrode 3 d and the anode 12 A of the display organic EL element 11 A are in contact with each other. The anode 12 A is an electrode having characteristics of reflecting light without transmission. The anode 12 A is formed of Al and other metals, but can be formed of a single metal layer having a high reflectance, or a multilayered structure of ITO (indium tin oxide) and metal.

The display organic EL element 11 A is formed in each of the display pixels PEL, being isolated as an island. This display organic EL element 11 A is formed by laminating the anode 12 A, an emissive layer 13 A, and the transparent cathode 14 A transmitting light emitted from the emissive layer 13 A, in this order. The transparent cathode 14 A is supplied with a power supply voltage CV (not shown). In this display organic EL element 11 A, holes injected from the anode 12 A and electrons injected from the transparent cathode 14 A are recombined in the emissive layer 13 A. The recombined holes and electrons excite organic molecules forming the emissive layer 13 A to generate excitons. Then, light is emitted from the emissive layer 13 A in a process of radiation of the excitons and released outside from the transparent cathode 14 A, completing light emission.

The light sensor 31 A is disposed on the transparent glass substrate 40 A, which is also formed with the driving TFT 61 A and the display organic EL element 11 A, in a position corresponding to the light detecting portions 30 x and 30 y . The light sensor 31 A is formed of a top gate type TFT.

That is, the buffer layer BF formed by laminating, for example, SiN x and SiO 2 in this order, the active layer 32 A formed by poly-crystallizing an a-Si film by laser beam irradiation, the gate insulating film 33 A, the gate electrode 34 A made of metal having a high melting point such as chromium or molybdenum, the interlayer insulating film 65 A, and the planarization insulating film 66 A are formed on the transparent glass substrate 40 A, in this order. Furthermore, the transparent cathode 14 A of the display organic EL element 11 A can be extended on the planarization insulating film 66 A. In this case, external light can be blocked from entering a back surface of the light sensor 31 A.

Light from the light source portions 20 x and 20 y enters the active layer 32 A through the back surface of the display panel 1 , i.e. through an exposed surface of the transparent glass substrate 40 A. The light sensor 31 A electrically detects the light received by the active layer 32 A, and outputs an electric current or a voltage corresponding to intensity of the light.

In the structure of this light sensor 31 A, the gate electrode 34 A for blocking light does not exist between the transparent glass substrate 40 A where light enters and the active layer 32 A. This increases an area of the active layer 32 A receiving light and improves sensitivity in light detection compared with the case where the light sensor 31 A is formed of a bottom gate type TFT (laminated with the transparent glass substrate, the gate electrode, the gate insulating film, and the active layer, in this order).

Furthermore, the driving TFT 61 A and the light sensor 31 A are formed of the top gate type TFTs so that these can be formed by the same steps, thereby preventing complexity of manufacturing steps. For example, manufacturing steps described below can be used.

The buffer layer BF is formed on the transparent glass substrate 40 A, and then the active layers 32 A and 62 A are formed on the buffer layer BF. The gate insulating films 33 A and 63 A are formed on these active layers 32 A and 62 A. Furthermore, the gate electrodes 34 A and 64 A are formed on the gate insulating films 33 A and 63 A, an the interlayer insulating film 65 A is formed on the gate insulating films 33 A and 63 A so as to cover the gate electrodes 34 A and 64 A. Then, the power supply line L 3 and the drain electrode 3 d are formed, and the planarization insulating film 66 A is formed to cover the power supply line L 3 and the drain electrode 3 d. The anode 12 A is formed on the planarization insulating film 66 A, the emissive layer 13 A is laminated on the anode 12 A, and the transparent cathode 14 A is formed thereon. Furthermore, the transparent cathode 14 A of the display organic EL element 11 A is formed on the planarization insulating film 66 A above the light sensor 31 A so that external light can be blocked from entering the back surface of the light sensor 31 A.

As described above, in this embodiment, the display portion 10 , the light source portions 20 x and 20 y , and the light detecting portions 30 x and 30 y are formed on the same transparent glass substrate 10 A integrally, so that the number of the components of the organic EL display device and complexity of the manufacturing steps can be reduced. Furthermore, the reflecting boards 51 x, 51 y, 52 x, and 52 y lead light emitted by the light source portions 20 x and 20 y through the back surface of the light detecting portions 30 x and 30 y (the same side as the back surface of the display panel 1 where no external light enters), so that an effect of external light can be prevented when the emitted light is detected. It is noted that the effect of the external light can be further prevented by providing the black matrix on each of the organic EL elements in a region other than the light detecting portions 30 x and 30 y.

Accordingly, accuracy in positional detection of the pointing object PT that touches or is placed close to the display portion 10 can be improved. Furthermore, the active layer 32 A of the light sensor 31 A is placed in a position where light is not blocked by the gate electrode 34 A (top gate type TFT), so that an area receiving light to be detected can be increased. This improves sensitivity in detection of entering light.

Next, a second embodiment of the invention will be described. In the first embodiment described above, the top emission type display organic EL element and the top emission type light source organic EL element, the top gate type driving TFT, and a light sensor formed of a top gate type TFT are integrally formed on the same substrate. In this embodiment, however, the display organic EL element and the light source organic EL element are of bottom emission type, the driving TFT is formed of a top gate type TFT, and the light sensor is formed of a bottom gate type TFT, all being integrally formed on the same substrate.

This embodiment will be described in detail with reference to drawings. The plan view of FIG. 1A applies to a plan view of this embodiment where the display organic EL element 11 A, the light source organic EL element 21 A, and the light sensor 31 A in FIG. 1A are changed to the bottom emission type display organic EL element 11 B, the bottom emission type light source organic EL element 21 B, and the light sensor 31 B formed of a bottom gate type TFT, respectively.

FIG. 5A is a schematic cross-sectional view of FIG. 1A for this embodiment along line A—A, and FIG. 5B is a schematic cross-sectional view of FIG. 1A for this embodiment along line B—B.

As shown in FIGS. 5A and 5B , the display portion 10 , the light source portions 20 x and 20 y , and the light detecting portions 30 x and 30 y are provided on the same transparent glass substrate 40 B, being integrally formed as a display panel 1 . This configuration reduces the number of components of the organic EL display device, reducing complexity of manufacturing steps, in a manner similar to the first embodiment. The transparent glass substrate 40 B of this embodiment is different from the transparent glass substrate 40 A of the first embodiment, and is formed on the front surface of the display panel 1 as an emissive surface.

Structures of the container 50 and the reflecting boards 51 x, 52 x, 51 y, and 52 y are the same as those shown in the schematic cross-sectional views of FIGS. 1B and 1C of the first embodiment.

A detecting process of the point P corresponding to a position where the pointing object touches or is placed close to the display portion 10 in this embodiment is the same as that of the first embodiment.

Next, structures of the display organic EL element 11 B, the driving TFT 61 B, and the light sensor 31 B of the display pixel PEL will be described in detail with reference to a schematic cross-sectional view. The operation of the display pixel PEL is the same as that of the first embodiment.

FIG. 6 is a schematic cross-sectional view of the display organic EL element 11 B and the driving TFT 61 B of the display pixel PEL, and the light sensor 31 B of the light detecting portions 30 x and 30 y and its neighborhood. FIG. 6 shows one of the display pixels PEL arrayed in a matrix on the display portion 10 . The display organic EL element 11 B of the display pixel PEL is of bottom emission type, and the driving TFT 61 B for driving the display organic EL element 11 B is of top gate type. Although not shown, the pixel selecting TFT 71 B is of top gate type in a manner similar to the driving TFT 61 B. The light sensor 31 B is formed of a bottom gate TFT.

These display organic EL element 11 B, the driving TFT 61 B, the pixel selecting TFT 71 B, and the light sensor 31 B are disposed on the same transparent glass substrate 40 B. In this embodiment, differing from the first embodiment, light released by the display organic EL element 11 B is emitted from the exposed surface of the transparent glass substrate 40 B. These elements will be described in detail hereafter.

A buffer layer BF formed by laminating, for example, SiN x and SiO 2 in this order, an active layer 62 B formed by poly-crystallizing an a-Si film by laser beam irradiation, a gate insulating film 63 B, and a gate electrode 64 B made of metal having a high melting point such as chromium or molybdenum are formed on the transparent glass substrate 40 B, in this order. A channel 62 Bc, a source 62 Bs, and a drain 62 Bd are provided in the active layer 62 B, the source 62 Bs and the drain 62 Bd being disposed on sides of the channel 62 Bc, respectively.

An interlayer insulating film 65 B laminated with an SiO 2 film, an SiN x film, and an SiO 2 film in this order is formed on the whole surfaces of the gate insulating film 63 B and the gate electrode 64 B. A contact hole C 4 is provided in the interlayer insulating film 65 B in a position corresponding to the source 62 Bs, and the power supply line L 3 to be supplied with a positive power supply voltage PVdd is provided therein by filling the hole with a metal such as Al.

A contact hole C 5 is provided in the interlayer insulating film 65 B in a position corresponding to the drain 62 Bd, and a drain electrode 3 d is provided therein by filling the hole with a metal such as Al. Furthermore, a planarization insulating film 66 B made of, for example, organic resin and planarizing a surface is provided on the whole surface. A contact hole C 6 is provided in the planarization insulting film 66 B in a position corresponding to the drain electrode 3 d, and metal such as Al fills the hole so that the drain electrode 3 d and the transparent anode 12 B of the display organic EL element 11 B are in contact with each other. The transparent anode 12 B is a transparent electrode formed of ITO (indium tin oxide).

The display organic EL element 11 B is formed in each of the display pixels PEL, being isolated as an island. This display organic EL element 11 B is formed by laminating the transparent anode 12 B, an emissive layer 13 B, and the cathode 14 B (e.g. formed of Al or magnesium-indium alloy) reflecting light emitted from the emissive layer 13 B without transmission, in this order. The cathode 14 B is supplied with a power supply voltage CV (not shown). Light emitted by the emissive layer 13 B is released from the transparent glass substrate 40 B through the transparent anode 14 B.

A light sensor 31 B is provided on the transparent glass substrate, which is also formed with the driving TFT 61 B and the display organic EL element 11 B, in a position corresponding to the light detecting portions 30 x and 30 y . The light sensor 31 B is formed of a bottom gate type TFT.

The gate electrode 34 B made of metal having a high melting point such as chromium or molybdenum, the gate insulating film 33 B serving as the buffer layer BF, the active layer 32 B formed by poly-crystallizing an a-Si film by irradiating laser beams thereto, the insulating films 35 B and 36 B, and the planarization insulating film 37 B are formed on the transparent glass substrate 40 B, in this order. Light from the light source portions 20 x and 20 y enters the active layer 32 B through the back surface of the display panel 1 , i.e. through an exposed surface on the side of the cathode 14 B. The light sensor 31 B electrically detects the light received by the active layer 32 B, and outputs an electric current or a voltage corresponding to intensity of the light.

In the structure of this light sensor 31 B, the gate electrode 34 B for blocking light does not exist between the exposed surface of the back surface of the display panel 1 where light enters and the active layer 32 B. This increases the area of the active layer 32 B receiving light and improves sensitivity in light detection compared with a case where the light sensor 31 B is formed of a top gate type TFT (not shown) (laminated with the glass substrate, the active layer, the gate insulating film, and the gate electrode, in this order).

The light sensor 31 B and the driving TFT 61 B can be manufactured by manufacturing steps described below, for example. The gate electrode 34 B is formed on the transparent glass substrate 40 B, and then the buffer layer BF serving as the gate insulating film 33 B is formed to cover the gate electrode 34 B. The active layers 32 B and 62 B are formed thereon, and the insulating film 35 B serving as the gate insulating film 63 B is formed on the active layers 32 B and the 62 B. Furthermore, the gate electrode 64 B is formed thereon, and the insulating film 36 B serving as the interlayer insulating film 65 B is formed to cover the gate electrode 64 B. Then, the power supply line L 3 and the drain electrode 3 d are formed, and the planarization insulating films 37 B and 66 B are formed to cover the power supply line L 3 and the drain electrode 3 d. The transparent anode 12 B is formed on the planarization insulating film 66 B, the emissive layer 13 B is laminated on the transparent anode 12 B, and the cathode 14 B is formed thereon.

As described above, in this embodiment, the display portion 10 , the light source portions 20 x and 20 y , and the light detecting portions 30 x and 30 y are formed on the same transparent glass substrate integrally, so that the number of the components of the organic EL display device can be reduced and complexity of the manufacturing steps can be suppressed. Furthermore, the reflecting boards 51 x, 51 y, 52 x, and 52 y let light emitted by the light source portions 20 x and 20 y enter the back surface of the light detecting portions 30 x and 30 y (the same side as the back surface of the display panel 1 where no external light enters) in a manner similar to the first embodiment, so that a detection error caused by an effect of external light can be prevented. Accordingly, accuracy in positional detection of the pointing object that touches or is placed close to the display portion 10 can be improved. Furthermore, the active layer 32 B of the light sensor 31 B is placed in a position where light is not blocked by the gate electrode 34 b (bottom gate type TFT), so that an area receiving light to be detected can be increased. This improves sensitivity in detection of entering light.

The reflecting boards 52 x and 52 y provided near the light detecting portions 30 x and 30 y in the first and second embodiments have reflecting surfaces which reflects light incident horizontally along the display panel 1 in a vertical direction, next reflects the light in a horizontal direction, and last reflects the light in a vertical direction to enter the light in the light detecting portions 30 x and 30 y of the back surface of the display panel 1 . However, reflecting angles of the other reflecting surfaces A, B, D, and E can be angles other than vertical or horizontal as far as the light can vertically enter the light detecting portions 30 x and 30 y through the back surface of the display panel 1 .

The embodiments described above can be applied to a non-organic electroluminescent display device using a non-organic material as an emissive layer.