SENSING DEVICE HAVING PHOTO SENSING ELEMENT ALTERNATELY OPERATED IN DIFFERENT BIASED STATES AND RELATED TOUCH-CONTROLLED DISPLAY DEVICE
The present invention provides a sensing device and a display device utilizing the sensing device. A photo sensing element of the sensing device is alternatively operated in a biased state and a reverse-biased state to prevent the stress issue. Furthermore, the sensing device improves the S/N ratio by generating an output signal through an active component. The display device including the sensing device prevents the stress issue and improves the S/N ratio by using specific driving signals.
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This application is a divisional application of and claims the benefit of U.S. patent application Ser. No. 13/103,999, filed May 9, 2011.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to a sensing device, and more particularly, to a sensing device employed in a touch-controlled display device.
2. Description of the Prior Art
Touch-controlled display devices are widely used in various electronic products in the market. When the touch source touches the figures or objects on the touch screen, a sensing device of the touch-controlled display device judges an occurrence of a touch event, and then an internal processing system operates according to a program compiled in advance. Traditionally, sensing devices employed in touch-controlled display devices may be categorized into two different types as shown in
Please refer to
Moreover, the sensing device shown in
In view of above, the present invention provides an innovative sensing device that may avoid the disadvantage of the conventional sensing device design. The characteristic of the present invention is that by a proper design of a biased signal which changes the biased state of the photo sensing element, alternately, the electric charges accumulated in the photo sensing element are released to thereby prevent the stress issue and accordingly solve the shifted I-V curve issue. Moreover, the present invention generates output signals by active components to thereby increase the overall signal-to-noise (S/N) ratio, and properly uses the control signal of the display device disposed in the sensing device as a biased signal to thereby save the cost of implementing an additional control circuit and improve the aperture ratio.
Since the photo sensing element may be an element having a two-terminal structure (e.g., a diode) or an element having a three-terminal structure (e.g. a transistor), different embodiments of the present invention therefore provide driving control signals of different timings to change the biased states of the photo sensing element that has a two-terminal structure or three-terminal structure, in order to solve the issue encountered by the conventional sensing device design.
According to one exemplary embodiment, a sensing device comprises: a photo sensing element, having a first terminal for receiving a second signal and a control terminal for receiving a first signal, and a second terminal; a first capacitor, having a first electrode electrically connected to the second terminal of the photo sensing element and a second electrode electrically connected to a third signal; and a first transistor, electrically connected to the second terminal of the photo sensing element and having a first terminal, a control terminal and a second terminal. Additionally, the first signal and the second signal are both driving signals each supporting two logic levels, and a voltage value corresponding to a high logic level of the first signal is higher than a voltage value corresponding to a high logic level of the second signal; and a voltage value corresponding to a low logic level of the first signal is not higher than a voltage value corresponding to a low logic level of the second signal.
According to another exemplary embodiment, a sensing device comprises: a photo sensing element, having a first terminal and a control terminal for receiving a first signal, wherein the first terminal of the photo sensing element is electrically connected to a second signal through at least one other element. The first signal and the second signal are both driving signals each supporting two logic levels, and a logic level transition of the first signal is not synchronized with a logic level transition of the second signal.
According to still another exemplary embodiment, a sensing device comprises: a photo sensing element, having a first terminal and a control terminal for receiving a first signal, wherein the first signal is a driving signal that supports two logic levels; and a first capacitor, having a first electrode electrically connected to the first terminal of the photo sensing element and a second electrode; and a first transistor electrically connected to the first terminal of the photo sensing element and having a first terminal, a control terminal and a second terminal.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
The concept of the present invention is illustrated with reference to different exemplary embodiments and relevant figures. Elements or devices with the same reference numeral in different figures have similar operation principles and technical effects. Thus, repeated description is omitted below for brevity. Moreover, different technical features mentioned in different exemplary embodiments are not limited to the exemplary embodiments only. In fact, in a reasonable scope of the present invention, one of the exemplary embodiments may be properly modified to have specific technical features of other exemplary embodiments.
Please refer to the lower part of
The first signal S1 is synchronized with the second signal S2 in this exemplary embodiment; however, in other exemplary embodiments of the present invention, the first signal S1 may not be synchronized with the second signal S2. When the first signal S1 is not synchronized with the second signal S2, the pulse falling edge timing corresponding to the second signal S2 may be equal to the pulse falling edge timing corresponding to the first signal S1. One of the possible relations is shown in
Moreover, the pulse falling edge timing corresponding to the second signal S2 may also lag behind the pulse falling edge timing corresponding to the first signal S1, and one of the possible relations is shown in
The relationship of voltage values corresponding to logic levels of the signals S1-S3 is detailed as follows. In order to alternately change the biased state of the first transistor TFT1, i.e., to make the first transistor TFT1 alternately operated at the forward-biased state and the reverse-biased state, the voltage value corresponding to the high logic level H1 of the first signal S1 must be higher than the voltage value corresponding to the high logic level H2 of the second signal S2, which is for making the first transistor TFT1 operated at the forward-biased state. The voltage value corresponding to the low logic level L1 of the first signal S1 must not be higher than the voltage value corresponding to the low logic level L2 of the first signal S2, which is for making the first transistor TFT1 operated at the reverse-biased state. Besides, as the sensing device 100 is still operated at the resetting phase when the second signal S2 has the high logic level H2, the second transistor TFT2 is not allowed to be conductive at this moment, in order to prevent a false judgment of the touch event. However, when the second signal S2 has the high logic level H2, the terminal voltage Va is inevitably raised. Hence, the selection of the voltage value corresponding to the high logic level H2 of the second signal S2 must ensure that the second transistor TFT2 would not be conductive.
Besides, the sensing device of the present exemplary embodiment is disposed in a touch-controlled display device to act as a necessary touch sensing means in practice. Please refer to
The arrangement of sensing devices 100 is similar to that of pixel elements 815. In the present invention, driving signals on the scan lines GL1-GLN are utilized for acting as the first signal S1 to bias the sensing devices 100. Thus, sensing devices 100 are respectively connected to the scan lines GL1-GLN, as shown in
It should be noted that in the first exemplary embodiment of the present invention, the terminal voltage Va is electrically connected to the control terminal of the second transistor TFT2; however, this is not meant to be a limitation of the present invention. In other exemplary embodiments, the terminal voltage Va may be electrically connected to the first terminal E21 or the second terminal E22 of the second transistor TFT2. Both alternative designs fall into the scope of the present invention.
The second exemplary embodiment of the present invention provides a sensing device as shown in
Please refer to the lower part of
In this exemplary embodiment, the first signal S1 is synchronized with the second signal S2; however, in other exemplary embodiments of the present invention, the first signal S1 may not be synchronized with the second signal S2. When the first signal S1 is not synchronized with the second signal S2, the pulse falling edge timing corresponding to the second signal S2 may be equal to the pulse falling edge timing corresponding to the first signal S1 as shown in
In the second exemplary embodiment of the present invention, the operation thereof is almost similar to that of the first exemplary embodiment. Since the second capacitor C2 and the fourth signal S4 are specially added in the second exemplary embodiment, the third signals S3 may be realized by the driving signals on the scan lines GL1-GLN in order to save the signal generating circuit or driving circuit required for generating the third signals S3.
Of course, the logic level transition timing of signals in the second exemplary embodiment of the present invention may also be similar to that shown in
Similarly, in the second exemplary embodiment of the present invention, the terminal voltage Va is electrically connected to the control terminal of the second transistor TFT2; however, this is not meant to be a limitation of the present invention. In another exemplary embodiment, the terminal voltage Va may be electrically connected to the first terminal E21 or the second terminal E22 of the second transistor TFT2. Both alternative designs fall within the scope of the present invention.
More specifically, the difference between the first exemplary embodiment and the second exemplary embodiment of the present invention is that the first signal S1 and the third signal S3 in the second exemplary embodiment both may be replaced by driving signals on the scan lines. The first capacitor C1 and the second capacitor C2 form a voltage divider. Therefore, when the high logic level H3 of the third signal S3 is coupled to the first capacitor C1 and the second capacitor C2, the terminal voltage Va generated at the sensing phase will not be over raised, and the intensity of the output current IDS corresponding to the present ambient light source and passing through the second transistor TFT2 in the read phase. Moreover, if the first signal S1 and the third signal S3 are both replaced by the scan line driving signals, the relation between the voltage levels of the signals S1-S3 is detailed as below. As the first signal S1 and the third signal S3 are driving signals having the same voltage level, the voltage value corresponding to the high logic level H1 of the first signal S1 is equal to the voltage value corresponding to the high logic level H3 of the third signal S3, and the voltage value corresponding to the low logic level L1 of the first signal S1 is equal to the voltage value corresponding to the low logic level L3 of the third signal S3. Moreover, the voltage values corresponding to the low logic level L1 of the first signal S1 and the low logic level L3 of the third signal S3 are not higher than the voltage value corresponding to the low logic level L2 of the second signal S2, and the voltage values corresponding to the high logic level H1 of the first signal S1 and the high logic level H3 of the third signal S3 are higher than the voltage value corresponding to the high logic level H2 of the second signal S2.
The exemplary implementation of disposing the sensing device of the present invention in a touch-controlled display device is illustrated below. Please refer to
The arrangement of sensing devices 200 is similar to that of pixel elements 915. In present invention, driving signals on the scan lines GL1-GLN are utilized for acting as the first signal S1 and the third signal S3 to bias the sensing devices 200. Thus, sensing devices 200 are respectively connected to the scan lines GL1-GLN, as shown in
Besides, in order to increase the S/N ratio of the sensing device, the third exemplary embodiment and the fourth exemplary embodiment, respectively shown in
The fifth exemplary embodiment of the present invention provides a sensing device that does not use any active component to generate the output signal, such as the sensing device 500 shown in
In the exemplary embodiments mentioned above, the sensing devices of the present invention are all implemented by photo sensing elements each having a three-terminal structure. However, by using different configuration of the control signal, a photo sensing element having a two-terminal structure maybe utilized, and the biased state of the photo sensing element having a two-terminal structure may be changed alternately, wherein the photo sensing element having a two-terminal structure may be a photo-diode or a silicon rich oxide (SRO) element. Please refer to the illustration as follows. As the photo sensing element that has a two-terminal structure includes only two terminals to control its biased state, the sixth exemplary embodiment and the seventh exemplary embodiment of the present invention therefore provide a technical means which allows the two-terminal photo sensing element in the sensing device to stay in the forward-biased state and reverse-biased state alternately by using the first signal S1 only. Please refer to the sensing devices 600 and 700 shown in
Similarly, in the sixth exemplary embodiment and the seventh exemplary embodiment of the present invention, the terminal voltage Va is electrically connected to the control terminal G2 of the second transistor TFT2. However, in other exemplary embodiments of the present invention, the terminal voltage Va may be electrically connected to the first terminal E21 or the second terminal E22 of the second transistor TFT2.
Moreover, according to the signal configuration mentioned above, the photo sensing element of the sensing device according to the present invention may be a photo diode or other photo semiconductor element. Please refer to
When the first signal S1 has a high logic level H1, the photo semiconductor element PSD stays in a forward-biased state, and when the first signal S1 has a low logic level L1, the photo semiconductor element PSD stays in a reverse-biased state. It should be noted that the implementation of the photo semiconductor element PSD is not limited in the present invention. Any semiconductor element with photo sensing effect may be utilized in the exemplary embodiment of the present invention.
Similarly, in the eighth exemplary and the ninth exemplary of the present invention, the terminal voltage Va is electrically connected to the control terminal G2 of the second transistor TFT2. However, in other exemplary embodiments of the present invention, the terminal voltage Va may be electrically connected to the first terminal E21 or the second terminal E22 of the second transistor TFT2.
Please note that the different technical features mentioned in the aforementioned exemplary embodiments are not limited to these exemplary embodiments only. In fact, within the reasonable scope of the present invention, proper modification may be made to one exemplary embodiment to make the exemplary embodiment have specific technical features of other exemplary embodiments. For example, regarding the sixth exemplary embodiment to the ninth exemplary embodiment, an extra third transistor TFT3 may be added at the output terminal of the second transistor TFT2 (i.e., the first terminal E21 or the second terminal E22) to isolate the output current IDS of each sensing device, thereby improving the S/N ratio. Besides, similar to the first exemplary embodiment to the fifth exemplary embodiment, the sixth exemplary embodiment to the ninth exemplary embodiment of the present invention may also be disposed in a display device.
To sum up, the alternating current (AC) signal characteristic of the first signal S1 or/and the second signal S2 in the present invention is utilized for making the transistor in the sensing device stay in the forward-biased state and the reverse-biased state alternately, in order to prevent the stress issue. Besides, the driving signals on scan lines of the display device may be utilized for controlling transistors in the sensing devices to thereby save the cost of a signal generating circuit. Moreover, an output signal may be generated through an active component to thereby improve the S/N ratio of the sensing device.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
Claims
1. A sensing device, comprising:
- a photo sensing element, having a first terminal and a control terminal, wherein the control terminal is configured to receive a first signal, and the first terminal of the photo sensing element is electrically connected to a second signal through at least one other element;
- wherein the first signal and the second signal are both driving signals each supporting two logic levels, and a logic level transition of the first signal is not synchronized with a logic level transition of the second signal.
2. The sensing device of claim 1, wherein the photo sensing element is a photo diode or a silicon rich oxide (SRO) element.
3. The sensing device of claim 1, wherein the at least one other element is a first capacitor having a first electrode electrically connected to the first terminal of the photo sensing element and a second electrode electrically connected to the second signal, and the first terminal of the photo sensing element receives the second signal through the first capacitor; and the sensing device further comprises a first transistor electrically connected to the first terminal of the photo sensing element and having a first terminal, a control terminal and a second terminal.
4. The sensing device of claim 3, wherein when the first signal has a high logic level, the first transistor is not conductive.
5. The sensing device of claim 3, wherein the first transistor is electrically connected to the first terminal of the photo sensing element through the control terminal of the first transistor, and the control terminal of the first transistor is electrically connected to the first electrode of the first capacitor.
6. The sensing device of claim 3, further comprising:
- a second capacitor, having a first electrode electrically connected to the first electrode of the first capacitor and a second electrode.
7. The sensing device of claim 3, further comprising:
- a second transistor, having a first terminal electrically connected to a second terminal of the first transistor, a control terminal for receiving a control signal and a second terminal electrically connected to a data read line, wherein the control signal is utilized for controlling a conductive state of the second transistor.
8. A touch-controlled display device, comprising:
- a plurality of scan lines for receiving scan line driving signals;
- a plurality of data lines;
- a plurality of sensing devices of claim 3 arranged in a matrix, each of the plurality of sensing devices being coupled to at least one of the plurality of scan lines; and
- a plurality of pixel elements arranged in a matrix, each of the plurality of pixel elements being coupled to one of the plurality of scan lines and to one of the plurality of data lines, respectively.
9. The touch-controlled display device of claim 8, wherein each of the sensing devices further comprises:
- a second capacitor, having a first electrode electrically connected to the first electrode of the first capacitor and a second electrode;
- wherein the first signal and the second signal are different scan line driving signals of the scan line driving signals, and an activation timing of the second signal is prior to an activation timing of the first signal.
10. A sensing device, comprising:
- a photo sensing element, having a first terminal and a control terminal for receiving a first signal, wherein the first signal is a driving signal that supports two logic levels;
- a first capacitor, having a first electrode electrically connected to the first terminal of the photo sensing element and a second electrode; and
- a first transistor electrically connected to the first terminal of the photo sensing element and having a first terminal, a control terminal and a second terminal.
11. The sensing device of claim 10, wherein the first transistor is electrically connected to the first terminal of the photo sensing element through the first terminal of the first transistor, and the first terminal of the first transistor is electrically connected to the first electrode of the first capacitor.
12. A touch-controlled display device, comprising:
- a plurality of scan lines for receiving scan line driving signals;
- a plurality of data lines;
- a plurality of sensing devices of claim 10 arranged in a matrix, each of the plurality of sensing devices being coupled to at least one of the plurality of scan lines; and
- a plurality of pixel elements arranged in a matrix, each of the plurality of pixel elements being coupled to one of the plurality of scan lines and to one of the plurality of data lines, respectively.
Type: Application
Filed: Jan 27, 2014
Publication Date: May 22, 2014
Applicant: AU OPTRONICS CORP. (HSIN-CHU)
Inventors: Tzu-Wei Liu (Hsin-Chu), Hsueh-Ying Huang (Hsin-Chu)
Application Number: 14/164,280
International Classification: G01J 1/46 (20060101); G06F 3/042 (20060101);