Abstract:
An embedded optical induction input device and method of implementing the same. Such a device includes a light sensing circuit and a conversion circuit. The light sensing circuit generates an induced current signal based on the variations of the intensity of light irradiation received as caused by a touch-control-position event; and the conversion circuit is connected to the light sensing circuit and receives an induced current derived therefrom. The conversion circuit is provided with a first transistor and a second transistor coupled together, that are driven by a positive and a negative biases having the same period but different phases, thus the induced current signals are converted into induced voltage signals based on the alternative turn-on&#39;s and turn-off&#39;s of the first transistor and the second transistor.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a touch-control display technology, and in particular to an embedded optical induction input device and an embedded optical induction input method. 
     2. The Prior Arts 
     Nowadays, touch-control panels are the most simple, direct, and efficient means of communications between users and electronics devices, thus, they have become very popular and are widely utilized. As such, touch-control panels operated under various operation principles are developed and commercialized. Among them, the most commonly used touch-control panels include: capacitor type, resistor type, sonic wave type, infrared light type, and in-cell (embedded) type touch-control panels, etc. Wherein, the development of in-cell (embedded) touch-control panels is getting most of the attentions. Compared with the conventional resistor or capacitor type touch-control panels both requiring additional touch-control panels to be installed on the associated display panels, for an in-cell (embedded) touch-control panel, the touch-control function is built-in and incorporated into a display panel without additional touch-control panels. Therefore, it has the advantages of light-weight, small size, and high optical performance, and thus is held in high esteem in the industry. 
     Presently, most of the in-cell (embedded) touch-control panels are of an optical sensor type, wherein, a photo sensor embedded in a display panel is used to detect the light intensity distribution on a panel in determining a touch-control-position event, and in such a process, the photo sensitivity amorphous silicon material is utilized, while such photo sensors can be the amorphous silicon thin-film-transistor (a-Si TFT) sensors produced directly by utilizing the existing manufacturing process and equipment. Moreover, according to the different light sensing principles, the light sensing circuit can be classified into a charge mode and a current mode. As shown in  FIG. 1 , while in a charge mode, a first transistor  10  is turned on, thus charging a storage capacitor (Cst)  12 , next, the first transistor  10  is turned off, and then a part of the charges in the storage capacitor  12  will be leaked out due to a photo current flowing through a second transistor  14 . As the light intensity is getting stronger, the charge leakage is getting faster because the photocurrent is proportional to the light intensity. Afterwards, the first transistor  10  is turned on again to read the charges remaining in the storage capacitor  12  in determining a touch-control-position event. Furthermore, as shown in  FIG. 2 , while in a current mode, a switching transistor  16  is turned on, so that current will flow into a detector transistor  18 , the magnitude of current flowing through detector transistor  18  is dependent on the intensity of light exposing on the detector, thus the magnitude of a current is read directly in determining a touch-control-position event. 
     For the light sensing circuit in a current mode, since the outputs of this circuit are signals of a light induction current, however, for the circuits responsible for system processing, the signals utilized are predominantly voltage signals, thus each of the respective read line  20  is connected to a resistor  22 , as shown in  FIG. 3 , so that the output light induction current signals are converted into light induction voltage signals, and then that are transferred to a read circuit  24  via a read line  20  in determining the occurrence of a touch-control-position event. However, in this respect, in general, a large quantity of resistors have to be added additionally onto a printed-circuit-board (PCB), and that is quite inefficient, besides, the cost is high. 
     In view of the problems and shortcomings of the prior art, the present invention provides an embedded optical induction input device and a method implementing the same, so as to solve the afore-mentioned problems of the prior art. 
     SUMMARY OF THE INVENTION 
     The major objective of the present invention is to provide an embedded optical induction input device and a method of implementing the same. In the application of the present invention, transistors are utilized to replace the original resistors, hereby achieving the purpose of converting induced current signals into induced voltage signals; meanwhile, the transistors utilized can be produced concurrently by making use of the existing manufacturing processes and equipment of semiconductor arrays, thus being able to be embedded and incorporated into a display device. 
     The another object of the present invention is to provide an embedded optical induction input device and a method of implementing the same. Since an embedded optical induction input device can be produced in a standardized manufacturing process and equipment without having to add touch-control panel and additional resistors, therefore, its cost can be reduced to the minimum, the modularized product thus produced can be relatively thin and light-weight, thus achieving wider scope of applications. 
     According to one aspect of the present invention, an embedded optical induction input device is provided, including a plurality of regularly arranged induction input units used in sensing touch-control-position events, with each of the respective induction input units comprising at least a or a plurality of light sensing circuits and a conversion circuit. Wherein, the light sensing circuit is used to generate an induced current signal according to the variations of the intensity of light irradiation received caused by a touch-control-position event; and the conversion circuit is connected to the light sensing circuit and having a first transistor and a second transistor connected together, thus that are turned on and turned off alternatively in converting induced current signals into induced voltage signals. 
     According to another aspect of the present invention, an embedded optical induction input method implementing the above-mentioned embedded optical induction input device is provided, including the following steps: firstly, applying a high level voltage and a low level voltage respectively on the gates of the above-mentioned first transistor and second transistor, hereby turning on the first transistor and turning off the second transistor, thus utilizing the first transistor in converting induced current signals produced by a light sensing circuit into induced voltage signals as an output; subsequently, applying a low level voltage and a high level voltage on the gates of the first transistor and second transistor respectively, hereby turning off the first transistor and turning on the second transistor, thus utilizing the second transistor in converting induced current signals into induced voltage signals as an output; and finally, repeating the above-mentioned steps, so that the first transistor and the second transistor convert alternatively the induced current signals into the induced voltage signals, thus proceeding continuously with sensing the occurrences of touch-control-position events by making use of the polarity variation of the two transistors. 
     Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The related drawings in connection with the detailed description of the present invention to be made later are described briefly as follows, in which: 
         FIG. 1  is a circuit diagram of a charge type light sensing circuit according to the prior art; 
         FIG. 2  is a circuit diagram of a current type light sensing circuit according to the prior art; 
         FIG. 3  is a circuit of a light sensing circuit utilizing a resistor in converting induced current signals into induced voltage signals according to the prior art; 
         FIG. 4  is a circuit diagram of an optical induction input device according to a first embodiment of the present invention; 
         FIG. 5  is an enlarged view of a portion of the circuit as shown in  FIG. 4 ; 
         FIG. 6(   a ) is a circuit diagram of a first stage driving according to a first embodiment of the present invention; 
         FIG. 6(   b ) is a circuit diagram of a second stage driving according to a first embodiment of the present invention; 
         FIG. 7  is a circuit diagram of an optical induction input device according to a second embodiment of the present invention; 
         FIG. 8  is a circuit diagram of an optical induction input device according to a third embodiment of the present invention; and 
         FIG. 9  is a circuit diagram of an optical induction input device according to a fourth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The purpose, construction, features, functions and advantages of the present invention can be appreciated and understood more thoroughly through the following detailed description with reference to the attached drawings. 
     In the application of the present invention, transistors are used to replace the conventional resistors in performing the same functions. However, in case that a single transistor is utilized, there still exists the problem of charge trapping, thus causing the shifting of threshold voltage (Vt) of a transistor, and resulting in the instability of the output signals, hereby creating reliability problems. As such, in the present invention, AC is used for driving, and voltages of different polarities are provided alternatively to the gates, drains and sources of two transistors respectively, thus keeping the trapped charges balanced, and solving the Vt shifting problems. As such, achieving effective compensation of Vt shifting through driving transistors with AC. 
     Referring to  FIGS. 4 and 5  for an embedded optical induction input device  30  according to a first embodiment of the present invention, including a plurality of light sensing circuits  32  arranged in an array, that are disposed on the corresponding liquid crystal device. In a first embodiment of the present invention, a conversion circuit  34  and a plurality of light sensing circuits  32  operated in its cooperation are referred to as a induction input unit. Naturally, no matter the quantity or constructions of the light sensing circuits  32 , they can work well with the conversion circuit  34  of the present invention. As shown in  FIGS. 4 &amp; 5 , each of the respective light sensing circuits  32  includes a switching transistor  321  and a detector transistor  322 . This switching transistor  321  controls the current flowing into the detector transistor  322  based on the signals received from a gate line  35 , so that the detector transistor  322  may generate an induced current signal based on its intensity of light exposing on the detector. The conversion circuit  34  includes a first transistor (T 1 )  341  and a second transistor (T 2 )  342  coupled to each other. The first transistor (T 1 )  341  and the second transistor (T 2 )  342  are connected to the light sensing circuit  32 , and are used to convert alternatively the induced current signals into the induced voltage signals, and then transfer the induced voltage signals to a read circuit  38  through a read line  36  in determining a touch-control position event as based on the location that generates the induced current signals. In the above configuration, the switching transistor  321 , the detector transistor  322 , the first transistor  341 , and the second transistor  342  are all thin film transistors. 
     More specifically, in a conversion circuit  34 , a gate of a second transistor  342  is connected to a first bias line  343 , with its drain connected to a second bias line  344 ; a source of a second transistor  342  is connected to a source of a first transistor  341 , thus being able to receive the above-mentioned induced current signals, and both the sources of a first transistor  341  and the second transistor  342  are connected respectively to a light sensing circuit  32 . A gate of a first transistor  341  is connected to a second bias line  344 , with its drain connected to the first bias line  343 , so as to supply voltage signals of the same period but opposite phases respectively to a second transistor  342  and a first transistor  341  through a first bias line  343  and a second bias line  344 . Since both the first transistor  341  and the second transistor  342  can be considered having the function of a resistor respectively, thus they are used to convert current signals induced by the light sensing circuit  32  into voltage signals. In addition, since the two transistors  341  and  342  are biased with two square waves of opposite phases, so that the voltages of the two transistors  341  and  342  may change their polarities with time, thus balancing the trapped charges. 
     In the following, referring to  FIG. 4  and  FIG. 6  for a description of the steps of an embedded optical induction input method according to a first embodiment of the present invention. When signals are transmitted to a switching transistor  321  from a gate line  35 , a switching transistor  321  is turned on, so that a current flows into a detector transistor  322 . When a user touches a touch-control panel, an induction current signal Iphoto is generated by a corresponding detector transistor  322  based on the differences of the intensities of light irradiations received, and then the signal is transferred into a conversion circuit  34 . Wherein, the conversion circuit  34  is composed of two transistors. As such, the driving process is composes of two stages: firstly, in the first stage, referring to  FIG. 6(   a ), applying two biases each of a high level voltage and a low level voltage respectively on a first bias line  343  and a second bias line  344 , so that a first transistor  341  is turned off and a second transistor  342  is turned on. At this time, the second transistor  342  acts as the role of a resistor and converts the induction current signals (Iphoto) output by a light sensing circuit  32  into induction voltage signals, and then transfers that signals to a read circuit  38  through a read line  36 . Subsequently, in the second stage, referring to  FIG. 6(   b ), applying two biases each of a low level voltage and a high level voltage respectively on a first bias line  343  and a second bias line  344 , so that a first transistor  341  is turned on and a second transistor  342  is turned off. At this time, the first transistor  341  acts as the role of a resistor and converts induction current signals (Iphoto) output by a light sensing circuit  32  into induction voltage signals, and then transfers those signals to a read circuit  38  through a read line  36 . As such, the above-mentioned two-stage driving process is repeated continuously, so that the first transistor  341  and the second transistor  342  are used to convert the induction current signals into the induction voltage signals alternatively; thus the polarity variations of transistors  341  and  342  are utilized to detect continuously whether a touch-control-position event does indeed occur, and the polarity variations of transistors are utilized to compensate trapped charges, hereby preventing the shifting of the threshold voltage Vt of the transistors. 
     In addition to the first embodiment mentioned above, the present invention is further provided with other embodiments as follows by making use of two transistors as a conversion circuit. 
     Subsequently, referring to  FIG. 7  for an embedded optical induction input device according to a second embodiment of the present invention. In order for the induction current signals output from a light sensing circuit  32  to be more stable, an additional capacitor  40  can be added, and also connected in parallel with a conversion circuit  34  in forming a RC circuit, so that the induction voltage signals output by a conversion circuit  34  can be more stable. In this configuration, the structure of capacitor  40  can be realized by making use of the existing semiconductor array manufacturing process and equipment. The remaining structures and driving methods of the present invention are the same as those of the first embodiment, and therefore they will not be repeated here for brivity&#39;s sake. 
     Since there are quite a lot of reasons and mechanisms that may cause the shifting of threshold voltages of transistors, such as the structures, materials, or manufacturing processes of different kinds of transistors. Therefore, in a third embodiment of the present invention, more voltage signals are introduced to regulate the voltages of transistors. As shown in  FIG. 8 , a drain of a first transistor  341  is connected to a first bias line  343 , a gate of the first transistor is connected to a third bias line  345 , a source of the first transistor is connected to a source of a second transistor  342 , and also the sources of the first transistor  341  and the second transistor  342  are both connected to a light sensing circuit; a drain of the second transistor  342  is connected to a second bias line  344 , a gate of the second transistor is connected to a fourth bias line  346 . In the above structure, voltage signals of same phase but different levels are applied to the first bias line  343  and the fourth bias line  346 ; and the voltage signals on the second bias line  344  and the third bias line  345  are of the same phase but different levels. In the present embodiment, in the first stage (t 1 ) of the driving process, low level voltages of different levels are applied to the first bias line  343  and the fourth bias line  346 , and high level voltages of different levels are applied to the second bias line  344  and the third bias line  345 , so that the first transistor  341  is turned on, and the second transistor  342  is turned off. At this time, the first transistor  341  plays the role of resistor in converting an induction current signal (Iphoto) output by the light sensing circuit  32  into an induction voltage signal. Subsequently, in the second stage (t 2 ) of the driving process, high level voltages of different levels are applied to the first bias line  343  and the fourth bias line  346 , and low level voltages of different levels are applied to the second bias line  344  and the third bias line  345 , so that the first transistor  341  is turned off, and the second transistor  342  is turned on. At this time, the second transistor  342  plays the role of resistor in converting induction current signals (Iphoto) output by the light sensing circuit  32  into induction voltage signals. As such, the above-mentioned two-stage driving process is repeated continuously, so that the first transistor  341  and the second transistor  342  are used in converting the induction current signals in turn into the induction voltage signals alternatively. 
     Finally referring to  FIG. 9  for a fourth embodiment of the present invention. As shown in  FIG. 9 , in a conversion circuit  34 , a gate of the first transistor  341  is connected to a first bias line  343 , its drain is connected to a constant voltage source (Vconstant)  347 , a source of the first transistor  341  is connected to a source of a second transistor  342 , so as to receive an induced current signal; a gate of the second transistor is connected to a second bias line  344 , with its drain connected to the same constant voltage source (Vconstant)  347 . In this configuration, the first bias line  343  and the second bias line  344  supply voltage signals of the same period but opposite phases respectively to the first transistor  314  and the second transistor  342 , so that the first transistor  314  and the second transistor  342  convert induction current signals into induction voltage signals in turn alternatively. 
     Summing up the above, in the application of the various embodiments of present invention, transistors are utilized to replace the resistors used in the prior art in achieving the objective of converting the induction current signals into induction voltage signals. Since the transistors utilized in these processes can be produced concurrently with the semiconductor arrays by means of the existing semiconductor array manufacturing process and equipment, such that they can be incorporated and embedded into the existing display device. Furthermore, since the device of the present invention can be produced by means of a standardized manufacturing process, thus there is no need to add another touch-control panel and the additional resistor elements, so that its cost can be reduced to the minimum, its modularized product be relatively thin and light-weight, and be able to achieve wider scope of applications. 
     The above detailed description of the preferred embodiment is intended to describe more clearly the characteristics and spirit of the present invention. However, the preferred embodiments disclosed above is not intended to be any restrictions to the scope of the present invention. Conversely, its purpose is to include the various changes and equivalent arrangements which are within the scope of the appended claims.