Patent Application
20100164921
This invention relates to a display apparatus. Particularly, the present invention relates to a display apparatus wherein operation of an illuminating section which emits, after light coming in from the other face side of a display panel is received by an external light sensor element to obtain reception light data, illuminating light based on the reception light data obtained by the external light sensor element is controlled by a control section.
Display apparatus such as a liquid crystal display apparatus and an organic EL display apparatus have such an advantage that they are slim, light-weighted and low in power consumption.
Among such display apparatus, a liquid crystal display apparatus has a liquid crystal panel as a display panel including a liquid crystal layer filled between a pair of substrates. The liquid crystal panel is, for example, of the transmission type wherein the liquid crystal panel modulates illuminating light emitted from an illuminating apparatus such as a backlight provided on the rear face of the liquid crystal panel and transmits the modulated illuminating light therethrough. Then, display of an image is carried out with the modulated illuminating light on the front face of the liquid crystal panel.
This liquid crystal panel is, for example, of the active matrix type and includes a TFT array substrate on which a plurality of thin film transistors (TFT: Thin Film Transistor) which function as pixel switching elements. In the liquid crystal panel, an opposing substrate is disposed in an opposing relationship so as to face the TFT array substrate, and a liquid crystal layer is provided between the TFT array substrate and the opposing substrate. In this liquid crystal panel of the active matrix type, a pixel switching element inputs a potential to a pixel electrode to vary the voltage to be applied to the liquid crystal layer thereby to control the transmission factor of light which is transmitted through the pixel to modulate the light.
In such liquid crystal panels as described above, a liquid crystal panel has been proposed wherein a light receiving element which receives light to obtain reception light data is built as a position sensor element in a display region in addition to a TFT which functions as a pixel switching element described hereinabove.
Since a liquid crystal panel wherein a light receiving element is built in as a position sensor element as described above can implement a function as a user interface, it is called I/O touch panel (Input-Output touch panel). In a liquid crystal panel of this type, the necessity to separately install a touch panel of the resistance film type or the electric capacitance type on the front face of the liquid crystal panel is eliminated. Therefore, miniaturization of an apparatus can be implemented readily, and a contribution to reduction in thickness of the liquid crystal panel can be made. Further, where a touch panel of the resistance film type or the electric capacitance type is installed, since light to be transmitted through the display region is sometimes decreased by the touch panel or the light suffers from interference, the picture quality of the display image is sometimes deteriorated. However, appearance of this fault can be prevented by building a light receiving element as a position sensor in the liquid crystal panel in such a manner as described above.
In such a liquid crystal panel as described above, visible light of light reflected from a detection object body such as, for example, a finger of a user or a touch pen touching with the front face of the liquid crystal panel is received by light receiving elements built in as position sensor elements. Thereafter, the position at which the detection object body touches is specified based on reception light data obtained by the light receiving elements built in as position sensor elements, and an operation corresponding to the specified position is carried out by the liquid crystal display apparatus itself or by a different electronic apparatus connected to the liquid crystal display apparatus.
Where a light receiving element built in as a position sensor element is used to detect the position of a detection object body as described above, reception light data obtained by the light receiving element sometimes includes much noise by an influence of visible light included in external light. Further, where dark display is carried out in a display region, it is difficult for a light receiving element provided on a TFT array substrate to receive visible light emitted from a detection object body. Therefore, it is sometimes difficult to detect the position accurately.
In order to correct such a fault as described above, a technique has been proposed which uses invisible light such as infrared light other than visible light. Here, a light receiving element built in as a position sensor element receives invisible light such as infrared light to acquire reception light data, and the position of a detection object body is specified based on the acquire data (refer to, for example, Japanese Patent Laid-Open No. 2005-275644, Japanese Patent Laid-Open No. 2004-318819 and Japanese Patent Laid-Open No. 2006-301864).
Further, a technique is known that a light receiving element which functions as an external light sensor for receiving external light including visible light is formed, and operation when an illuminating apparatus such as a backlight emits illuminating light is controlled based on reception light data obtained by the external light sensor element. Here, the light receiving element which functions as an external light sensor element is formed in a peripheral region positioned around a display region of a display panel. For example, if light of a high light illuminance is received by the external light sensor, then the operation of the illuminating apparatus is controlled so that the illuminating apparatus may emit illuminating light of a higher light illuminance. On the other hand, if light of a low light illuminance is received by the external light sensor, then the operation of the illuminating apparatus is controlled so that the illuminating apparatus may emit illuminating light of a lower light illuminance. Consequently, the fault that the quality of the display image is deteriorated by an influence of external light can be corrected, and increase of the power consumption can be suppressed.
However, in the foregoing case, since a light receiving element which functions as an external light sensor element is formed in a peripheral region positioned around a display region of a display panel, it is sometimes difficult to adjust the influence of external light coming into the display region with a high degree of accuracy. Therefore, sometimes it is not easy to correct the fault that the quality of a display image is deteriorated by an influence of external light. Further, since light such as external light undergoes multipath reflection and stray light is sometimes generated, the accuracy in position detection sometimes drops.
In this manner, deterioration of the image quality or deterioration of the position detection accuracy sometimes occurs.
Accordingly, the present invention provides a display apparatus which can implement improvement of the image quality and the position detection accuracy.
According to the present invention, there is provided a display apparatus including a display panel having a plurality of pixels disposed in a display region thereof and an illuminating section for emitting illuminating light from one face side of the display panel to the display region, the display apparatus having an external light sensor element for receiving light coming in from the other face side of the display panel and a control section for controlling operation of the illuminating section to emit the illuminating light based on reception light data obtained by reception of the light by the external light sensor element, the external light sensor element being disposed in the display region.
In the present invention, light coming in from the other face side of the display panel is received by the external sensor element in the display region.
According the present invention, a display apparatus which can implement improvement of the image quality and the position detection accuracy can be provided.
Examples of an embodiment according to the present invention are described.
As shown in
The liquid crystal panel 200 is of the active matrix type and has a TFT array substrate 201, an opposing substrate 202 and a liquid crystal layer 203 as shown in
In this liquid crystal panel 200, the TFT array substrate 201 and the opposing substrate 202 are opposed to each other with a distance placed therebetween. The liquid crystal layer 203 is provided in such a manner as to be sandwiched between the TFT array substrate 201 and the opposing substrate 202.
Further, as shown in
Here, the liquid crystal panel 200 is of the transmission type, and the backlight 300 is disposed in such a manner as to be positioned on the TFT array substrate 201 side. In the liquid crystal panel 200, a face of the TFT array substrate 201 opposite to the face which is opposed to the opposing substrate 202 is illuminated with illuminating light emitted from the backlight 300. This liquid crystal panel 200 includes a display region PA in which a plurality of pixels (not shown) are disposed to display an image. Illuminating light emitted from the backlight 300 disposed on the rear face side of the liquid crystal panel 200 is received from the rear face through the first polarizing plate 206, and the light received from the rear face is modulated in the display region PA. In particular, a plurality of TFTs are provided as pixel switching elements (not shown) in such a manner as to correspond to pixels on the TFT array substrate 201. As the TFTs serving as pixel switching elements are switching controlled to modulate the illuminating light received from the rear face. Then, the modulated illuminating light is emitted to the front face side through the second polarizing plate 207, and an image is displayed in the display region PA.
In the present embodiment, the liquid crystal panel 200 is a so-called I/O touch panel. Therefore, although details are hereinafter described, light receiving elements (not shown) are formed as position sensor elements for detecting the position of a detection object body when the detection object body is contacted with or positioned closely to the front face of the liquid crystal panel 200 on the opposite side to the rear race on which the backlight 300 is disposed. For example, the position sensor elements are formed so as to include a photodiode and are used for detection of the position of a detection object body such as, for example, a finger of a user or a touch pen. The light receiving elements which form the position sensor elements receive, on the front face side of the liquid crystal panel 200, reflection light reflected by the detection object body. In particular, the light receiving elements receive reflected light directed from the opposing substrate 202 side toward the TFT array substrate 201 side. Then, the light receiving elements which form the position sensor elements carry out photoelectric conversion to produce reception light data.
Further, in the present embodiment, although details are hereinafter described, the light receiving elements of the liquid crystal panel 200 which receive external light coming in from the front face side of the liquid crystal panel 200 are formed as external light sensor elements (not shown). For example, the external light sensor elements are formed so as to include a photodiode. Here, the external light sensor element receives external light coming in from the opposing substrate 202 side toward the TFT array substrate 201 side. Then, the light receiving element which forms the external light sensor element carries out photoelectric conversion to produce reception light data.
As shown in
In the present embodiment, the light source 301 of the backlight 300 includes, for example, a visible light source 301a and an infrared light source 301b as shown in
The data processing section 400 has a control section 401 and a position detection section 402 as shown in
The control section 401 of the data processing section 400 includes a computer and is configured so as to control operation of the liquid crystal panel 200 and the backlight 300. The control section 401 supplies a control signal to the liquid crystal panel 200 to control operation of the plural pixel switching elements (not shown) provided on the liquid crystal panel 200 to display an image in the display region PA of the liquid crystal panel 200. For example, the control section 401 causes the liquid crystal panel 200 to execute line-sequential driving to display an image.
Further, the control section 401 supplies a control signal to the liquid crystal panel 200 to control operation of the plural position sensor elements provided on the liquid crystal panel 200 and serving as the light receiving elements to collect reception light data from the position sensor elements. For example, the control section 401 causes the liquid crystal panel 200 to execute line-sequential driving to collect the reception light data.
Further, the control section 401 supplies a control signal to the liquid crystal panel 200 to control operation of the plural external light sensor elements provided on the liquid crystal panel 200 and serving as the light receiving elements to collect reception light data from the external light sensor elements.
Further, the control section 401 supplies a control signal to the backlight 300 to control operation of the backlight 300 to irradiate illuminating light from the backlight 300.
Here, the control section 401 controls operation of the backlight 300 to emit illuminating light based on the reception light data obtained by reception of light of the external light sensor elements.
Although details are hereinafter described, in the present embodiment, if the reception light data obtained by reception of light of the external light sensor elements indicate that the illuminance of the received light is high, then high power is supplied to the backlight 300 so as to cause the backlight 300 to irradiate illuminating light of a higher illuminance. On the other hand, if the illuminance of the received light is low, then lower power is supplied to the backlight 300 so as to cause the backlight 300 to irradiate illuminating light of a lower illuminance.
The position detection section 402 detects the position of the display region of the liquid crystal panel 200 at which a detection object body is contacted with or positioned closely to the liquid crystal panel 200 based on reception light data collected from the plural light receiving elements provided as the position sensor elements on the liquid crystal panel 200.
The liquid crystal panel 200 is described in detail.
As shown in
In the liquid crystal panel 200, a plurality of pixels P are disposed in a horizontal direction x and a vertical direction y in the display region PA such that they are juxtaposed in a matrix as shown in
Here, each pixel P has a pixel switching element (not shown) formed therein although details are hereinafter described. Further, the pixel P is formed so as to include a light receiving element (not shown) serving as a position sensor element or an external light sensor element.
In the present embodiment, as shown in
In the liquid crystal panel 200, the peripheral region CA is provided such that it surrounds the periphery of the display region PA as shown in
In particular, the selection switch 12 and the vertical driver 13 line-sequentially drive the pixel switching elements (not shown) provided individually for the pixels P in the display region PA based on driving signals supplied thereto from the display driver 14 to carry out image display.
Further, the selection switch 12 and the vertical driver 13 reads out reception light data from the light receiving elements 32 provided as the position sensor elements 32a in the display region PA based on driving signals supplied from the sensor driver 15 and outputs the reception light data to the position detection section 402. Then, the position detection section 402 detects the position in the display region PA of the liquid crystal panel 200 at which a detection object body such as a finger of a user or a touch pen is contacted with or positioned closely to the display region PA based on the reception light data outputted from the position sensor elements 32a.
Similarly, the selection switch 12 and the vertical driver 13 read out reception light data from the light receiving elements 32 provided as the external light sensor elements 32b in the display region PA based on driving signals supplied thereto from the sensor driver 15 and outputs the reception light data to the control section 401. Then, the control section 401 controls operation of the backlight 300 to emit illuminating light based on the reception light data outputted from the external light sensor elements 32b.
As shown in
Further, as shown in
In the light transmitting region TA, illuminating light emitted from the backlight 300 passes from the TFT array substrate 201 side to the opposing substrate 202 side. Here, in the light transmitting region TA, a color filter layer 21 is formed as shown in
Meanwhile, in the light blocking region RA, a black matrix layer 21K is formed as shown in
In this light blocking region RA, a light receiving region SA is formed as shown in
In this light receiving region SA, a light receiving element 32 is formed as a position sensor element 32a so as to receive light advancing from the opposing substrate 202 side toward the TFT array substrate 201 side on a face of the TFT array substrate 201 opposing to the opposing substrate 202. In particular, as shown in
The individual components of the liquid crystal panel 200 are described.
The TFT array substrate 201 is described below.
The TFT array substrate 201 is a substrate of an insulator which passes light therethrough and is formed, for example, from glass. The TFT array substrate 201 has a pixel switching element 31, an auxiliary capacitance element Cs, a position sensor element 32a and a pixel electrode 62 formed on a face thereof opposing to the opposing substrate 202 as shown in
It is to be noted that, in
The individual components of the TFT array substrate 201 are described.
The pixel switching element 31 is formed on a face of the TFT array substrate 201 on the side opposing to the opposing substrate 202 with an insulating layer 42 interposed therebetween as shown in
As shown in
In particular, in the pixel switching element 31, the gate electrode 45 is formed using a metal material such as, for example, molybdenum.
Meanwhile, in the pixel switching element 31, the gate insulating film 46g is formed using an insulating material such as a silicon dioxide film.
Further, in the pixel switching element 31, the semiconductor layer 48 is formed using, for example, low temperature polycrystalline silicon. Further, on the semiconductor layer 48, a channel formation region 48C is formed so as to correspond to the gate electrode 45, and a pair of source-drain regions 48A and 48B are formed in such a manner as to sandwich the channel formation region 48C therebetween. The pair of source-drain regions 48A and 48B have a pair of low-density impurity regions 48AL and 48BL formed thereon in such a manner as to sandwich the channel formation region 48C therebetween. Further, a pair of high-density impurity regions 48AH and 48BH having a higher density of impurities than the source-drain regions 48AL and 48BL are formed in such a manner as to sandwich the pair of low-density impurity regions 48AL and 48BL therebetween.
In the pixel switching element 31, each of the source electrode 53 and the drain electrode 54 is formed by filling a conductive material such as aluminum into an opening provided in an insulating layer 49, which covers the semiconductor layer 48, and carrying out patterning.
The auxiliary capacitance element Cs is formed on a face of the TFT array substrate 201 on the side opposing to the opposing substrate 202 with the insulating layer 42 interposed therebetween as shown in
The position sensor element 32a is a light receiving element 32 and is formed on a face of the TFT array substrate 201 on the side opposing to the opposing substrate 202 with the insulating layer 42 interposed therebetween as shown in
In particular, in the position sensor element 32a, the control electrode 43 is formed using a metal material such as, for example, molybdenum. Meanwhile, the insulating film 46s is formed using an insulating material such as a silicon dioxide film. Further, the semiconductor film 47 is formed from low temperature polycrystalline silicon and is configured such that it has a PIN structure wherein, though not shown in
The pixel electrode 62 is formed so as to cover an interlayer insulating film 60 formed so as to cover a face of the TFT array substrate 201 opposing to the opposing substrate 202 as shown in
The opposing substrate 202 is described.
The opposing substrate 202 is a substrate of an insulator which passes light therethrough similarly as in the case of the TFT array substrate 201 and is formed from glass. The opposing substrate 202 is opposed in a spaced relationship to the TFT array substrate 201 as shown in
The components of the opposing substrate 202 are described.
The color filter layer 21 is formed on a face of the opposing substrate 202 on the side opposing to the TFT array substrate 201 as shown in
The black matrix layer 21K is formed in the light blocking region RA such that it defines a plurality of pixels P in the display region PA as shown in
The flattening film 22 is formed on a face of the opposing substrate 202 on the side opposing to the TFT array substrate 201 in such a manner as to correspond to the light transmitting region TA and the light blocking region RA as shown in
The opposing electrode 23 is formed on a face of the opposing substrate 202 on the side opposing to the TFT array substrate 201 as shown in
The liquid crystal layer 203 is described.
The liquid crystal layer 203 is sandwiched between the TFT array substrate 201 and the opposing substrate 202 as shown in
It is to be noted that, to the liquid crystal panel 200, an FFS (Field Fringe Switching) structure which is one of transverse electric field modes can be applied as an example of an application as shown in
As shown in
As shown in
As shown in
As shown in
The visible light source control section 411 of the control section 401 is configured so as to control the visible light source 301a based on reception light data D obtained by reception of light by the external light sensor element 32b to cause the visible light source 301a to emit visible light.
As shown in
For example, the visible light source control section 411 stores, in a memory (not shown) thereof, a lookup table wherein the reception light data D and the control data CTa representative of a value of power to be supplied to the visible light source 301a are associated with each other. The visible light source control section 411 uses the lookup table, and the visible light source control section 411 controls. In particular, the visible light source control section 411 carries out, after it acquires the reception light data D, a data process of extracting control data CTa corresponding to the reception light data D from the lookup table. Then, the visible light source control section 411 controls operation of the visible light source 301a based on the extracted control data CTa.
The infrared light source control section 412 of the control section 401 is configured so as to control operation of the infrared light source 301b of the backlight 300 to emit infrared light based on reception light data D obtained by reception of light by the external light sensor element 32b as shown in
As shown in
For example, the infrared light source control section 412 stores, in a memory (not shown) thereof, a lookup table wherein control data CTb representative of a value of power to be supplied to the infrared light source 301b and reception light data D are associated with each other. The infrared light source control section 412 uses this lookup table, and the visible light source control section 411 controls. In particular, the infrared light source control section 412 carries out, after it acquires the reception light data D, a data process of extracting control data CTb corresponding to the reception light data D from the lookup table. Then, the infrared light source control section 412 controls operation of the infrared light source 301b based on the extracted control data CTb.
In the following, operation of the liquid crystal display apparatus 100 described above when it displays an image is described.
As shown in
Therefore, when an image is to be displayed, a selection pulse is supplied from the vertical driver 13 to the gate line G1 to place the pixel switching element 31 into an on state. Together with this, an image signal is supplied from the selection switch 12 to the data line S1, and the pixel switching element 31 writes the image signal into the auxiliary capacitance element Cs and the liquid crystal layer 203. In other words, a voltage is applied to the liquid crystal layer 203. Consequently, the direction of liquid crystal molecules in the liquid crystal layer 203 varies, and illuminating light emitted from the backlight is modulated by and passes through the liquid crystal layer 203. Therefore, image display is carried out on the front face of the liquid crystal panel.
In the following, operation of the liquid crystal display apparatus 100 described above when it detects a position with or to which a detection object body such as a finger of a user is contacted or moved in the display region PA of the liquid crystal panel 200 is described.
If a detection object body F such as a finger of a user is contacted with or moved to the display region PA of the liquid crystal panel 200, then reflection light reflected by the detection object body F is received by the position sensor elements 32a formed on the liquid crystal panel 200 as shown in
Here, the backlight 300 irradiates illuminating light R including visible light VR and infrared light IR as planar light upon the rear face of the liquid crystal panel 200. Then, the illuminating light R is irradiated upon the detection object body F through the liquid crystal panel 200 and is reflected by the detection object body F. Then, the reflection light H reflected by the detection object body F is received by the position sensor elements 32a.
At this time, the visible light VR in the illuminating light R is absorbed by various portions of the liquid crystal panel 200 and received in a state wherein the intensity thereof is decreased by the position sensor elements 32a. In contrast, the infrared light IR in the illuminating light R is received in an intensity higher than that of the visible light VR by the position sensor elements 32a because the ratio at which it is absorbed by various portions of the liquid crystal panel 200 is lower than that of the visible light VR.
Then, after reception light data of a signal intensity corresponding to the intensity of the received light are produced by the position sensor elements 32a, the reception light data are read out by the peripheral circuits. Then, the position at which the detection object body F contacts with the display region PA is detected by the position detection section 402 (refer to
As shown in
Here, in the position sensor element 32a which is a light receiving element, the control electrode 43 is connected to a power supply voltage line HD formed from aluminum (Al), and a power supply voltage VDD is supplied. Meanwhile, an anode electrode 51 is connected to a floating diffusion FD. Further, a cathode electrode 52 is connected to the power supply voltage line HD, and the power supply voltage VDD is supplied.
Further, the reset transistor 33 is a TFT including a gate electrode, for example, of molybdenum and a semiconductor layer of polycrystalline silicon. The reset transistor 33 is connected at one of terminals thereof to a reference voltage line HS formed from aluminum (Al), and a reference voltage VSS is supplied. Further, the reset transistor 33 is connected at the other terminal thereof to the floating diffusion FD. The reset transistor 33 is connected at the gate thereof to a reset signal line HR formed from aluminum (Al), and resets the potential of the floating diffusion FD when a reset signal is applied to the gate electrode.
The amplification transistor 35 is a TFT including a gate electrode, for example, of molybdenum and a semiconductor layer of polycrystalline silicon and is connected at one of terminals thereof to the power supply voltage line HD such that the power supply voltage VDD is supplied. The amplification transistor 35 is connected at the other terminal thereof to the selection transistor 36. Further, the amplification transistor 35 is connected at the gate electrode thereof to the floating diffusion FD and forms a source follower circuit.
The selection transistor 36 is, for example, a TFT including a gate electrode of molybdenum and a semiconductor layer of polycrystalline silicon, and is connected at one of terminals thereof to the amplification transistor 35 and at the other terminal thereof to a data line S2. Further, the gate electrode is connected to a readout line HRe formed from aluminum (Al) such that a readout signal (Read) is supplied. The selection transistor 36 is configured such that, if the readout signal is supplied to the gate electrode, then it is placed into an on state and outputs reception light data amplified by the amplification transistor 35 to the data line S2.
Here, capacitance 34 is generated between the floating diffusion FD and the reference voltage line HS to which the reference voltage VSS is applied, and the voltage of the floating diffusion FD varies in response to the amount of charge accumulated in the capacitance 34.
In the present embodiment, the sensor driver 15 outputs driving signals to the selection switch 12 and the vertical driver 13 to drive the position sensor circuit so that reception light data is read out from the light receiving elements 32 provided as the position sensor elements 32a in the display region PA and outputted to the position detection section 402 (refer to
In the following, operation of the liquid crystal display apparatus 100 described above when it detects external light and controls the backlight 300 is described.
As shown in
In particular, the switch SW1 of the first external light sensor element 32ba is turned OFF, and the switch SW2 of the second external light sensor element 32bb is turned ON. In this state, resetting of the second external light sensor element 32bb is turned ON/OFF once to detect light to obtain reception light data. Since the second external light sensor element 32bb is in a light blocked state, it measures dark current in the light blocked state, and reception light data of the second external light sensor element 32bb is transmitted to the comparator CP.
Then, time (for example, the number of steps) until after the detection value of reception light data after start of light reception by the second external light sensor element 32bb exceeds a predetermined reference value is counted by the difference mathematical operation circuit SE and stored into the memory.
Then, the switch SW2 of the second external light sensor element 32bb is turned OFF and the switch SW1 of the first external light sensor element 32ba is turned ON. In this state, resetting of the first external light sensor element 32ba is turned ON/OFF once to detect light to obtain reception light data. Since the first external light sensor element 32ba is not in a light blocked state and can receive external light, current when light is not blocked to the comparator CP is measured. Then, the reception light data is transmitted to the comparator CP.
Then, the difference mathematical operation circuit SE counts the time (for example, the number of steps) until after the detection value of the reception light data after reception of light of the first external light sensor element 32ba is started exceeds a predetermined reference value and stores the time into the memory.
Then, the detection result of the first external light sensor element 32ba and the detection result of the second external light sensor element 32bb stored in the memory of the difference mathematical operation circuit SE are read out. Then, the difference mathematical operation circuit SE carries out a difference mathematical operation process of subtracting the detection result of the second external light sensor element 32bb from the detection result of the first external light sensor element 32ba and outputs difference data. In other words, the difference mathematical operation circuit SE outputs difference data obtained by subtracting the dark current from the detection result when light is not blocked.
Then, the control section 401 receives the difference data as reception light data D obtained by the external light sensor element 32b (refer to
In the present embodiment, operation of the infrared light source 301b of the backlight 300 is controlled based on the difference data obtained as the reception light data D of the external light sensor element 32b as described hereinabove with reference to
For example, if the illuminance of received external light is high, then the infrared light source control section 412 carries out control so that the infrared light source 301b irradiates infrared light of a higher luminance. On the other hand, if the illuminance of the received external light is low, then the infrared light source control section 412 carries out control so that the infrared light source 301b irradiates infrared light of a lower luminance.
As shown in
Further, in the present embodiment, in addition to the infrared light source 301b of the backlight 300, control of operation of the visible light source 301a of the backlight 300 is carried out by the visible light source control section 411 based on difference data obtained as reception light data D of the external light sensor element 32b in such a manner as described above. The visible light source control section 411 controls such that, though not shown, if the illuminance of the received light is high, then the visible light source 301a irradiates visible light of a higher luminance, but if the illuminance of the received light is low, then the visible light source 301a irradiates visible light of a lower luminance.
As described above, in the present embodiment, the external light sensor elements 32b including the first external light sensor element 32ba and the second external light sensor element 32bb are disposed in the display region PA as shown in
As illustrated in
As shown in
Further, as shown in
Therefore, in the present embodiment, by providing an external light sensor element 32b in the display region PA as described above, light of a high intensity can be received.
Accordingly, with the present embodiment, since the influence of external light to come into the display region PA can be adjusted with a high degree of accuracy, occurrence of a fault that the quality of the display image is deteriorated by the influence of external light can be prevented.
More particularly, in the present embodiment, an external light sensor element 32b for receiving external light including visible light is disposed in the display region PA, and the external light sensor element 32b detects the signal amplitude, which increases in proportion to the luminance of external light, as a voltage or current value. Thereafter, the control section 401 uses the detection data to carry out luminance adjustment of the backlight 300. Generally, in an environment wherein external light, particularly, sunlight, comes in, it is sometimes difficult to recognize an image because of reflection in the display region PA. However, in the present embodiment, the visible light source 301a of the backlight 300 is controlled so that, for example, light of a luminance higher than the reflection luminance is emitted as outgoing light. Therefore, occurrence of a fault that the quality of the display image deteriorates can be prevented.
Further, although, in a state wherein external light is dark as in the case of the dark, occurrence of deterioration of the picture quality is suppressed, in this instance, the luminance of visible light which the visible light source 301a of the backlight 300 irradiates as illuminating light is controlled so as to be dropped. In particular, in the present embodiment, after the external light sensor element 32b receives external light, for example, in case of use in the open in which the intensity of external light is high, operation of the backlight is controlled so as to raise the backlight luminance. On the other hand, in case of use in an environment wherein the intensity of external light is low as in the case of indoor use, operation of the backlight is controlled so as to establish a state wherein the backlight luminance is low. Therefore, with the present embodiment, power consumption can be reduced in addition to the effects described above.
Further, in the present embodiment, since it can be prevented that light such as external light is multiple-reflected in the display panel and stray light is generated, the accuracy in position detection can be improved. Further, with the present embodiment, since a touch panel of the resistance type is not provided, the overall thickness can be reduced.
Further, in the present embodiment, the operation of the infrared light source 301b when it emits infrared light is controlled by the control section 401 based on reception light data obtained by reception of light by the external light sensor element 32b. Here, the control section 401 controls such that, where the illuminance of the received light is high, the infrared light source 301b irradiates infrared light of a higher luminance, but where the illuminance of the received light is low, the infrared light source 301b irradiates infrared light of a lower luminance as described hereinabove (refer to
Generally, natural light includes infrared light in an optical intensity substantially equal to that of visible light. Therefore, for example, when the time is approximately 12:00, natural light including infrared light of an intensity higher than that of reflected light of infrared light reflected by a detection object body such as a finger sometimes comes into the position sensor elements 32a, and it is sometimes difficult to carry out position detection of a detection object body with a high degree of accuracy. Therefore, in the present embodiment, high power (for example, 300 mW) is supplied to the infrared light source 301b based on reception light data obtained by reception of light by the external light sensor element 32b as illustrated in
In contrast, where the time ranges from 0:00 to 12:00 or 18:00 to 24:00, since the optical intensity of natural light is low and indoor use is carried out frequently, external light does not include much infrared light. Therefore, for example, within the time zones, external light of an intensity higher than that of light of infrared light reflected by a detection object body comes in no case into the position sensor elements 32a, and position detection of a detection object body can be carried out with a high degree of accuracy without being influenced by external light. Therefore, in the present embodiment, power (for example, 50 mW) lower than that in the case described hereinabove is supplied to the infrared light source 301b based on reception light data obtained by reception of light by the external light sensor element 32b.
Conventionally, in order to prevent occurrence of a fault caused by coming in of natural light including infrared light of a high intensity, high power (for example, 300 mW) is supplied to the infrared light source 301b as indicated by a dotted line in
Accordingly, in the present embodiment, the power consumption can be reduced.
In addition, in the present embodiment, infrared light whose absorption factor by such members as a liquid crystal layer and a glass substrate is low are received by the position sensor elements 32a. Therefore, since the backlight luminance for obtaining an arbitrary detection signal can be made lower than that of visible light, the present embodiment can further reduce the power consumption.
Furthermore, in the present embodiment, the position sensor elements 32a and the external light sensor elements 32b are disposed such that they are juxtaposed alternately in each of the horizontal direction x and the vertical direction y. In other words, the external light sensor elements 32b are disposed uniformly over the overall display region PA. Therefore, the influence (panel surface luminance or the like) of incoming external light can be adjusted readily over the overall display region PA.
Further, the light receiving elements of the external light sensor elements for measuring the amount of visible light observed by the eyes of a human being accurately and feeding back the amount to the backlight for visible light and position sensor elements having a high S/N ratio can be formed by the same fabrication process.
In the following, an embodiment 2 according to the present invention is described.
In the present embodiment, band gaps of semiconductor layers of the position sensor elements 32a and the external light sensor elements 32b are different from each other. Except this point, the present embodiment is similar to the embodiment 1. Therefore, description of overlapping portions is omitted.
In the present embodiment, a semiconductor layer in which the position sensor elements 32a receive and photoelectrically convert reflected light of a detection object body and another semiconductor layer in which the external light sensor elements 32b receive and photoelectrically convert external light have band gaps different from each other.
Here, the semiconductor layer in which photoelectric conversion is carried out by the position sensor elements 32a is formed such that it has a band gap narrower than that of the semiconductor layer in which photoelectric conversion is carried out by the external light sensor elements 32b.
The position sensor element 32a receives infrared light included in reflected light reflected from a detection object body. Therefore, the semiconductor layer in which photoelectric conversion is carried out by the position sensor element 32a is formed from polycrystalline silicon or crystalline silicon whose band gap is narrow as shown in
On the other hand, the external light sensor element 32b receives visible light defined by a wavelength range from 350 nm to 700 nm. Therefore, the semiconductor layer in which photoelectric conversion is carried out by the external light sensor element 32b is formed from amorphous silicon or microcrystalline silicon wherein the optical band gap is distributed broadly. This semiconductor layer is formed such that, for example, the band gap is 1.6 eV.
In this manner, in the present embodiment, the semiconductor layer in which photoelectric conversion is carried out by the position sensor elements 32a is formed such that it has a band gap narrower than that of the semiconductor layer in which photoelectric conversion is carried out by the external light sensor elements 32b. Therefore, in the present embodiment, infrared light included in reflection light reflected by a detection object body can be received with a high sensitivity by the position sensor elements 32a. Meanwhile, visible light included in external light can be received with a high sensitivity by the external light sensor element 32b.
As shown in
Accordingly, with the present embodiment, since the influence of external light to come into the display region PA can be adjusted with a high degree of accuracy, occurrence of a fault that the quality of the display image is determined by an influence of external light can be prevented. Further, since it can be prevented that light such as external light is multiple-reflected in the display panel and stray light is generated, the accuracy in position detection can be improved.
In the following, an embodiment 3 according to the present invention is described.
Meanwhile,
The present embodiment is different from the embodiment 1 in that an infrared filter IRF is provided so as to correspond to some of external light sensor elements 32b of the light receiving elements 32. Further, the present embodiment is different from the embodiment 1 in part of a relationship between the principal components of the control section 401 and inputting/outputting of data to/from the other members. Except this point, the present embodiment is similar to the embodiment 1. Therefore, description of overlapping portions is omitted.
The light receiving elements 32 are described.
As shown in
Here, as shown in
It is to be noted that, though not shown, in the external light sensor element 32b in which the infrared filter IRF is provided, a second external light sensor element 32bb is provided separately from the first external light sensor element 32ba similarly as in
As shown in
Here, the infrared filter IRF includes a red filter layer 21Rs and a blue filter layer 21Bs as shown in
In the present embodiment, the infrared filter IRF is provided in the opening 21a provided in the black matrix layer 21K on the opposing substrate 202.
This infrared filter IRF is formed at a step same as the step at which the red filter layer 21R and the blue filter region 21B which form the color filter layer 21 are formed.
For example, coating liquid including a coloring pigment of red and a photo resist material is applied by spin coating to the overall area including formation regions of the red filter layer 21R of the color filter layer 21 and the red filter layer 21Rs of the infrared filter IRF to form a red resist film (not shown). Then, the red resist film is patterned by a lithography technique to form the red filter layer 21R of the color filter layer 21 and the red filter layer 21Rs of the infrared filter IRF.
Thereafter, coating liquid including a coloring pigment of blue and a photo resist material is applied by spin coating to the overall area including formation regions of the blue filter layer 21B of the color filter layer 21 and the blue filter layer 21Bs of the infrared filter IRF to form a blue resist film (not shown). Then, the blue resist film is patterned by a lithography technique to form the blue filter layer 21B of the color filter layer 21 and the blue filter layer 21Bs of the infrared filter IRF. Here, the patterning is carried out such that the blue filter layer 21Bs is layered on the red filter layer 21Rs.
It is to be noted that visible light VR can be absorbed suitably by layering at least two from among a red filter layer, a green filter layer and a blue filter layer for the three primary colors. Therefore, the configuration of the color filter laminate 21ST is not limited to that which is formed using a red filter layer and a blue filter layer. For example, all of a red filter layer, a green filter layer and a blue filter layer for the three primary colors may be layered to form the color filter laminate 21ST.
The control section 401 is described.
As shown in
For example, in the visible light source control section 411, a lookup table wherein control data CTa representative of a value of power to be supplied to the visible light source 301a and reception light data D are associated with each other is stored in the memory (not shown) similarly as in the embodiment 1. The infrared light source control section 412 uses this lookup table, and the visible light source control section 411 controls.
On the other hand, in the control section 401, the infrared light source control section 412 receives reception light data Db obtained by reception of external light GH incoming through the infrared filter IRF by the external light sensor element 32b, different from the case of the embodiment 1 as illustrated in
For example, in the infrared light source control section 412, a lookup table wherein control data CTb indicative of a value of power to be supplied to the infrared light source 301b and reception light data Db are associated with each other is stored in a memory (not shown). The infrared light source control section 412 uses the lookup table and the visible light source control section 411 controls.
As described above, in the present embodiment, the infrared light source control section 412 controls operation of the infrared light source 301b based on the reception light data Db produced by reception of external light GH which includes much infrared light IR by the external light sensor element 32b. Therefore, since the illuminance of infrared light can be controlled with a high degree of accuracy, detection of a detection object body such as a finger can be carried out with a high degree of accuracy. Further, together with this, increase of power consumption can be suppressed, similarly as in the embodiment 1.
It is to be noted that, in carrying out the present invention, it is not limited to the embodiments described above, but various modified forms can be adopted. In other words, various particular items of the invention can be altered or combined suitably.
For example, while, in the present embodiments described above, a PIN sensor is provided in the light receiving elements 32, the present invention is not limited to this. For example, even if a PDN sensor including a photodiode of a PDN (P Doped−N+N type) structure is formed as the light receiving element 32, similar effects can be exhibited. In addition, for example, a phototransistor may be formed as the light receiving element 32.
Further, while, in the embodiments described above, illuminating light is irradiated such that it includes invisible light such as infrared light, the present invention is not limited to this. For example, the present invention can be applied also where illuminating light which includes only visible light without including invisible light is irradiated. Incidentally, invisible light signifies infrared light of a wavelength longer than 700 nm and ultraviolet light of a wavelength of 10 nm to 400 nm.
Further, while, in the embodiments described above, illuminating light is irradiated such that it includes infrared light as invisible light, the present invention is not limited to this. For example, illuminating light may be irradiated such that it includes ultraviolet light as invisible light.
Further, while, in the embodiments described above, the pixel switching element 31 is formed as a thin film transistor of the bottom gate type, the present invention is not limited to this.
As shown in
Further, while, in the embodiments described above, a plurality of light receiving elements 32 are provided so as to correspond to a plurality of pixels P, the present invention is not limited to this. For example, one light receiving element 32 may be provided for a plurality of pixels P, or conversely a plurality of light receiving elements 32 may be provided for one pixel P.
Further, in the embodiments described above, the light receiving elements 32 which function as position sensor elements 32a and external light sensor elements 32b are disposed in the display region PA such that the position sensor elements 32a and the external light sensor elements 32b exhibit a diced pattern as shown in
As shown in
In this instance, the second external light sensor element 32bb for receiving light coming in through a black matrix for blocking light from among the external light sensor elements 32b is not formed at the center of the display region PA but is formed around the same. Therefore, since the luminance of the display image does not drop, the image quality can be improved.
As shown in
In particular, an external light sensor element 32b may be disposed at two corner portions at an upper portion from among four corner portions of the display region PA of a rectangular shape as shown in (a) of
Also in this instance, the image quality can be improved similarly as described above.
As shown in
In particular, a plurality of external light sensor elements 32b may be disposed along a side extending in the vertical direction from among four sides which define a display region PA of a rectangular shape as shown in (a) of
Also in this instance, the image quality can be improved similarly as described above. Further, external light to come into the external light sensor element 32b is sometimes blocked by a housing which is installed so as to surround the display region PA. However, if a plurality of external light sensor elements 32b are disposed along a side which is less likely to be influenced by the housing, then external light can be received precisely. Therefore, control of later operation of the backlight 300 can be carried out appropriately.
As shown in
In particular, a plurality of external light sensor elements 32b may be disposed along two sides extending in the vertical direction from among four sides which define a display region PA of a rectangular shape as shown in (a) of
Also in this instance, similar effects to those described hereinabove can be obtained.
Further, the liquid crystal display apparatus 100 of the present embodiments can be applied as apart of various electronic apparatus.
As shown in
As shown in
As shown in
As shown in
As shown in
Further, while, in the embodiments described above, the plural light receiving elements 32 provided in the display region PA are configured such that each of them functions as one of the position sensor elements 32a and the external light sensor element 32b, the present invention is not limited to this. The plural light receiving elements 32 provided in the display region PA may be formed otherwise such that each of them functions as both of the position sensor elements 32a and the external light sensor element 32b. In other words, each light receiving element may be configured so as to serve as both of the position sensor element 32a and the external light sensor element 32b. For example, a switch for switching each light receiving element such that reception light data obtained when the light receiving element functions as the position sensor element 32a is outputted to the position detection section 402 but reception data obtained when the light receiving element functions as the external light sensor element 32b is outputted to the control section 401 is provided. Further, the switch may be configured such that operation thereof is controlled.
Further, while, in the embodiments described above, the first external light sensor element 32ba and the second external light sensor element 32bb are provided as the external light sensor elements 32b, the present invention is not limited to this. For example, similar effects can be obtained also where only the first external light sensor element 32ba is provided. Further, also the circuit configuration for obtaining reception light data from the external light sensor element 32b is not limited to the form described above. For example, a circuit configuration similar to that of the position sensor elements 32a may be applied.
Further, while, in the embodiments described hereinabove, both of the first external light sensor element 32ba and the second external light sensor element 32bb as the external light sensor elements 32b are provided so as to correspond to each of the pixels P, the present invention is not limited to this. For example, one second external light sensor element 32bb may be disposed for two first external light sensor elements 32ba. In this instance, it is preferable to use a configuration wherein, for example, reception light data obtained from one second external light sensor element 32bb is subtracted from reception data obtained individually from the two first external light sensor elements 32ba. By this configuration, it is possible to reduce the occupation area of the light receiving elements, and therefore, the light transmission factor with which light is transmitted for image display can be improved. Further, one of the first external light sensor element 32ba and the second external light sensor element 32bb may be provided additionally so as to correspond to each of the pixels P. In this instance, the first external light sensor elements 32ba and the second external light sensor elements 32bb may be disposed so as to be juxtaposed alternately in each of the horizontal direction x and the vertical direction y.
Further, in the embodiments, the red filter layer 21R, green filter layer 21G and blue filter region 21B are formed in a stripe shape and are formed so as to be juxtaposed in the horizontal direction x. Further, the light receiving region SA is formed in the neighborhood of the red filter layer 21R such that it is juxtaposed with the red filter layer 21R, green filter layer 21G and blue filter region 21B (refer to
Further, the present invention can be applied to liquid crystal panels of various types such as the IPS (In-Phase-Switching) type and the FFS (Field Fringe Switching) type. Furthermore, the present invention can be applied also to other display apparatus such as an organic EL display device and electronic paper.
It is to be noted that the position sensor element 32a in the embodiments described hereinabove corresponds to the position sensor element in the present invention. Further, the external light sensor element 32b in the embodiments described hereinabove in the embodiments described hereinabove corresponds to the external light sensor element in the present invention. Further, the liquid crystal display apparatus 100 in the embodiments described hereinabove corresponds to the display apparatus in the present invention. Further, the liquid crystal panel 200 in the embodiments described hereinabove corresponds to the display panel in the present invention. Further, the backlight 300 in the embodiments described hereinabove corresponds to the illuminating section in the present invention. Further, the TFT array substrate 201 in the embodiments described hereinabove corresponds to the first substrate in the present invention. Further, the opposing substrate 202 in the embodiments described hereinabove corresponds to the second substrate in the present invention. Further, the liquid crystal layer 203 in the embodiments described hereinabove corresponds to the liquid crystal layer in the present invention. Further, the control section 401 in the embodiments described hereinabove corresponds to the control section in the present invention. Further, the position detection section 402 in the embodiments described hereinabove corresponds to the position detection section in the present invention. Further, the display region PA in the embodiments described hereinabove corresponds to the display region in the present invention. Further, the infrared filter IRF in the embodiments described hereinabove corresponds to the invisible light filter in the present invention. Further, the visible light source control section 411 in the embodiments described hereinabove corresponds to the visible light source control section in the present invention. Further, the infrared light source control section 412 in the embodiments described hereinabove corresponds to the invisible light source control section in the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-314911 | Dec 2007 | JP | national |
| 2008-269590 | Oct 2008 | JP | national |
This application is a 371 U.S. National Stage filing of PCT/JP2008/071526, filed Nov. 27, 2008, which claims priority to Japanese Patent Application Number JP 2007-314911, filed Dec. 5, 2007, and the Japanese Patent Application Number JP 2007-314911, filed Dec. 5, 2007, all of which are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2008/071526 | 11/27/2008 | WO | 00 | 11/23/2009 |
