Patent Grant
8665223
The present invention contains subject matter related to Japanese Patent Application JP 2005-092154 filed in the Japanese Patent Office on Mar. 28, 2005, the entire contents of which being incorporated herein by reference.
1. Field of the Invention
The present invention relates to a display device and display method suitably applied to, for example, a liquid crystal display, an organic EL (Electro-Luminance) display and the like, and particularly to a display technology capable of receiving light in parallel with emitting light.
2. Description of the Related Art
In related art, in the case where on a display screen of a display device such as a television receiver a touch panel capable of being operated when touching the screen is configured, the touch panel provided separately from the display device is superimposed on the display screen.
As a configuration that uses the touch panel separately provided, for example, there is the one in which a thin transparent input detecting device is attached on the screen. This is a touch sensor using a conductive film, and there are a pressure type that detects the pressure, a static capacity type whose static capacity is changed when a human body is touched and the like. Further, there is an electromagnetic induction type that uses a specific pen to input a position. Those types have a structure in which a specific position-detecting panel is superimposed on the surface of a display panel.
Although the above types that use the detecting panel superimposed on the display panel use a simple principle of detecting touch, the deterioration of the display quality occurs inevitably, because some material is superimposed on the display panel. Furthermore, since a method of mainly detecting the capacity change is employed, it is difficult to detect inputs to two or more positions simultaneously.
Also, as a method of a touch panel in which a panel is not attached to the surface, there is an optical type. In this touch panel method, light-emitting elements (light-emitting diodes) and phototransistors are combined and disposed on the left, right, top and bottom of a panel, and light is shielded by the finger and the like to detect the position. The deterioration of the display quality does not occur in this optical type, but a device installed in the surrounding area of the display device becomes large, which is not suitable for portable equipment.
Recently, in order to solve the inconvenience of those touch panels in related art, the one is proposed in which the screen itself of the display device functions as the touch panel without separately providing the touch panel. Patent document 1 discloses such display device that emits light and receives light in parallel.
In the display device that emits light and receives light in parallel, for example, the display (light-emitting) by an image display light-emitting element arranged on a display screen is performed intermittently, and electric charge corresponding to the received light is stored in the light-emitting element itself, and then the electric charge stored is read out. As a display device in which such configuration is possible, there is an organic EL display, for example. Furthermore, in the case where a display pixel does not have a function of receiving light (storing electric charge), such as an LCD (Liquid Crystal Display) device, it is proposed a structure in which a light-receiving element is disposed adjacently to the display pixel and the light is received by the light-receiving element during the pause of the display (light-emitting).
In the case where this kind of display device that emits light and receives light simultaneously is configured, there is recognized a problem that the state of a signal when light is received considerably fluctuates due to the influence of outside light. In other words, for example, when it is assumed that on the display screen a position touched with the finger or the like is detected, the light-receiving conditions are largely different between the case where the light-receiving is detected in a dark room and the case where the light-receiving is detected outdoors in bright daylight, and therefore it is difficult to detect the touch or the like to the surface of the display device under the uniform light-receiving conditions.
Accordingly, when the above-described display device is applied to equipment capable of being used both outdoors and indoors, for example, as a display panel for a portable electronic apparatus, some treatment corresponding to the change in the strength of outside light is required, however, it is difficult to perform such treatment easily with the display device proposed in the past that emits light and receives light simultaneously.
In view of the above, it is desirable that the influence of outside light is easily removed in the case where the light-emitting and the light-receiving are performed in parallel simultaneously.
A display device according to an embodiment of the present invention is the one in which in the case where an image is displayed and light is received simultaneously or alternately on the display surface thereof, processing of making the display surface emit light to display an image is performed and light entering the display surface is received, where the light-receiving is performed two times in a state in which light is emitted for display use and in a state in which light is not emitted, and the state touched or approached to the display surface is detected from a difference in the quantities of received light of the two times.
With the above configuration, for example, in the state in which the display surface is made to emit the light, the quantity of received light detected by the elements at the position touched on the display surface becomes an approximately constant regardless of the presence or absence of outside light, because the touched object itself interrupts the outside light, even if the outside light exists. In addition, since the quantity of received light detected by elements in other positions changes from the constant quantity of received light, the state in which the corresponding position was touched can be determined in the case where the difference in the quantities of received light of two times is a predetermined level or more. A state of being approached to the display surface can also be determined similarly.
According to the embodiment of the present invention, a state in which the corresponding position was touched (or approached) can be determined in the case where the difference in the quantities of received light of two times is a predetermined level or more, and the touch or approach can be determined favorably without an influence of outside light and without an influence by the environment where the display device is used.
Hereinafter, a first embodiment of the present invention is explained with reference to
In this embodiment, the present invention is applied to a display device configured as an LCD (Liquid Crystal Display), in which a light-receiving element is disposed adjacently to each of light-emitting elements constituting the LCD display and so light-emitting (display) and light-receiving (readout) can be performed in parallel. Here, a display in this embodiment in which the light-emitting and light-receiving can be performed in parallel is called an I/O display, because it is a display in which an input (light-receiving) and output (display) of an image can be performed simultaneously. Further, as described later on, the I/O display in this embodiment can detect not only a touch that is a state of the screen being touched, but also an object approached to the screen, and when described as “the detection of touch” in the later explanation, except that a particular explanation is given, “the detection of approach” is also included.
The I/O display panel 20 is configured as an LCD display, in which transparent electrodes and the like are arranged on a transparent substrate such as a glass substrate and a plurality of pixels (display elements) are formed on a display area (sensor area) 21 in the matrix shape, and a backlight 15 is arranged in the back. The backlight 15 of this embodiment includes a plurality of light-emitting diodes arranged, for example, and on/off control of illumination of the backlight can be performed at a comparatively high speed. The on/off control in the illumination of the backlight 15 is performed in synchronization with the display drive in the display drive circuit 12.
In the I/O display panel 20, a plurality of light-receiving elements are arranged separately from the display elements. Specifically, for example, the light-receiving elements are arranged in a matrix shape adjacently to each of display pixels in the display area (sensor area) 21, and signal electric charge stored correspondingly to the quantity of light received by the light-receiving element is read out with the drive from a light-receiving drive circuit 13. The light-receiving drive circuit 13 includes a frame memory 13a therein, which is used for the necessary determination processing when reading out the light-receiving signal described later on.
The light-receiving signal (differential image signal described later on) read out and determined in the light-receiving drive circuit 13 is sent to an image processing portion 14 and the state of touch and the like are determined as an image, a coordinate position of the center of touch and the like are determined if necessary, and the determination results (coordinate data, recognition result and the like) are sent to the application program executing portion 11. In the application program executing portion 11, the processing corresponding to the application being in execution is performed. For example, processing of displaying the position, range and the like where the touch was detected is performed while displaying the image.
Next, an example of arrangement of a driver in the I/O display panel 20 of this embodiment is explained with reference to
Further, a light-receiving sensor (light-receiving element) 31c is arranged at the position adjacent to the pixel electrode 31b, and power supply voltage VDD is supplied thereto. A reset switch 31d and a capacitor 31e are connected to the light-receiving sensor (light-receiving element) 31c and the electric charge corresponding to the quantity of received light is stored in the capacitor 31e while being reset by the reset switch 31d. The electric charge stored is supplied to a signal output electrode 31j through a buffer amplifier 31f at the timing in which a readout switch 31g becomes “ON” and is output to the outside. The on/off of the reset switch 31d is controlled by the signal obtained at a reset electrode 31k and the on/off of the readout switch 31g is controlled by the signal obtained in a readout control electrode 31m.
For each frame cycle, readout of the signal received by the light-receiving elements is performed one time in the first half period in which the backlight is “ON” and is further performed one time in the last half period in which the backlight is “OFF”. Although it is necessary that the display of the image signal is performed for each frame at the frame cycle, the readout of the light-receiving signal is not necessarily performed for each frame cycle, and may not be performed for each frame cycle.
Next, the processing performed after reading out the light-receiving signal as described above is explained with reference to a flow chart of
The detected differential signal is sent to the image processing portion 14 as a differential image for one frame unit. In the image processing portion 14, the processing in which the supplied differential image is binarized into a predetermined level or more and less than the predetermined level is performed for each pixel unit (step S14). Further, computation to determine the center of gravity of a detected area being the predetermined level or more as a result of binarization is performed (step S15), and a coordinate position of the center of gravity determined (a coordinate position on the display area 21) is sent to the application program executing portion 11. In the application program executing portion 11, the supplied coordinate position of the center of gravity is specified as the center position of an object touched or approached (step S16).
Here, with respect to processing of detecting the touch or approach in this embodiment, a principle that an object touched or approached to the display surface of the I/O display panel 20 is detected without being affected by the outside light is explained referring to
In the case where the outside light entering the display panel is strong as shown in
Next, in the case where almost no outside light enters, as shown in
Hereupon, when comparing
Accordingly, by detecting a difference between a voltage at the time when the backlight is “ON” and a voltage at the time when the backlight is “OFF”, a position having a certain difference or more such as the difference between the voltages Vb and Vc can be determined as a position touched or approached. The processing of detection and determination shown in the above-described flow chart of
As shown in
As mentioned above, according to the I/O display panel of this embodiment, the state in which the display is touched or approached can favorably be detected with the uniform condition, regardless of the presence or absence of outside light. Further in this embodiment, since the processing that detects the difference in the light-receiving images of two times is performed, a fixed noise due to the uneven light-receiving characteristic of each pixel is removed simultaneously. It was confirmed in an experiment that capacity for removing the fixed noise was about 25 dB.
Further, in the principle of detecting a touch in this embodiment, since the reflected light of the light emitted from the display panel is detected at the position touched, the brightness of some level on the screen is needed to display the image regarding the position where the touch is detected. For example, a button to be pushed with a finger may need to be brightly displayed. Such display can be dealt with on the side of the application program that performs the display and detection of touch executed by the application program executing portion 11.
Furthermore, an area where the touch or approach is detected may be limited to a specific area in the display screen, and the area may be displayed brightly. In addition, in order to favorably detect the touch and the like irrespective of the brightness of the image displayed, infrared light may be configured as the light emitted from the backlight other than the visible light for image illumination and the infrared light is transmitted through the panel 20 with a constant brightness, and reflected light of the infrared light may be detected.
Moreover, although the processing that detects only one position where the I/O display panel was touched (or approached) was explained in the above explanation, the detection processing of this embodiment is also applied to simultaneous detection of a plurality of positions touched (or approached), in the case where the plurality of positions on the panel were touched (or approached) simultaneously. The simultaneous detection of the plurality of positions touched (or approached) can be performed by the processing of discriminating the light-receiving signal obtained from the panel.
A flow chart of
Processing up to this point is the same as the example shown in
With this judgment, if it is judged that there are a plurality of positions detected, a center of gravity of each position is calculated (step S22), and a coordinate position of the center of gravity respectively determined (coordinate position in the display area 21) is sent to the application program executing portion 11. In the application program executing portion 11, the supplied coordinate position of each center of gravity is specified as a center position of the object touched or approached (step S23).
Further, in the step S21, if it is judged that one position is touched, computation processing of determining a center of gravity of that position is performed (step S24) and the coordinate position of the center of gravity determined (coordinate position in the display area 21) is sent to the application program executing portion 11. In the application program executing portion 11, the supplied coordinate position of the center of gravity is specified as a center position of the object touched or approached (step S25).
As the processing of detecting touch or approach in the above-described embodiments, the processing of specifying the center position such as the center of gravity of the range touched was performed, however, instead of processing data on the coordinates of such position touched, the image data showing the range touched may be obtained to be used in various applications. The corresponding processing may be performed with an application program installed in the application program executing portion 11.
With the processing being performed based on those recognitions, an instruction to zoom in can be given, for example. Since such instruction can be given, the I/O display panel 20 of this embodiment, for example, may be connected to a personal computer apparatus and an operation of changing a command on the computer apparatus can be input in more natural ways with those image-recognitions.
Further, as shown in
Furthermore, since such detection of touch as this embodiment is possible, a handwriting input using a writing brush becomes possible, as shown in
Next, a second embodiment of the present invention is explained with reference to
An organic EL display is configured as the I/O display panel 60, in which a plurality of pixels (display elements) are formed in a matrix shape in a display area (sensor area) and the display elements also function as the light-emitting elements, and a light-emitting period and a light-receiving period is set by time division. Further, signal electric charge stored correspondingly to the quantity of light received during the light-receiving period is read out by the drive from a light-receiving drive circuit 53. The light-receiving drive circuit 53 includes inside a frame memory 53a to be used for determination processing (processing of detecting the difference) necessary when the light-receiving signal is read out.
The light-receiving signal (differential image signal) read out in the light-receiving drive circuit 53 and determined is sent to an image processing portion 54 and the state of touch and the like are determined as an image, a coordinate position of the center of the touch and the like are determined if necessary, and the results of determination (coordinates data, recognition results and the like) are sent to the application program executing portion 51. In the application program executing portion 51, the processing corresponding to the application being in execution is performed. For example, the processing of displaying in the displayed image a position, range and the like where the touch was detected is performed.
Then, during a period when no light is emitted in the light emitting element 61, electric charge is stored in the parasitic capacitance 61a generated in the light-emitting element 61, correspondingly to the quantity of light entering the display panel surface. The stored electric charge is read out to a receiving data signal wire 64 when a switch SW2 is ON. In addition, at the time of the start of the light-receiving period, the electric charge stored in the parasitic capacitance 61a at the time of the light-emitting is discharged by turning ON a reset switch SW3 for a moment. The “ON” of the switch SW2 is controlled by the signal obtained in a readout line selecting wire 63.
In this state, the readout of the light-receiving signal is performed two times, namely, the horizontal line readout 60b on the upper side adjacently to the light-emitting area 60a and the horizontal line readout 60c with a certain interval from that readout 60b are performed in one field period. The lines, where the readout 60b, 60c are performed, are changed sequentially in synchronization with the change of the light-emitting area 60a.
When performing the readout in this way, readout of the horizontal line 60b adjacent to the light-emitting area 60a becomes the one that can detect light reflected from the light-emitting area 60a and, as shown in
As described above, the present invention can also be applied to the case in which the display elements constituting a pixel are the light-emitting elements such as those in an organic EL display, and accordingly the present invention can be applied to both the case in which another light-emitting means different from a display panel is required, for example, in an LCD display and the case in which a display panel itself emits light. In the embodiments described above, an LCD display and organic EL display, for example, were explained as display panels respectively, however, the present invention can be applied to a display of another configuration if it is a display capable of incorporating the light-receiving elements.
It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.
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