Flat panel display in which a digitizer is integrated

A flat panel display comprises the following components. A display module has a lower glass substrate for fabricating thin film transistors, an upper glass substrate for fabricating a color filter, and a displaying molecule layer inserted between the lower glass substrate and the upper glass substrate. The lower glass substrate is connected electrically to a control circuit board via a flexible printed circuit board for driving the thin film transistors. And a backlight unit is fabricated beneath the display module and has a lightguide, a lamp disposed aside the lightguide to emit lights into the lightguide in the edgelight form, and a plurality of optical films disposed on the lightguide for scattering the lights emitted from the lightguide uniformly. The backlight unit comprises a sensor board disposed beneath the lightguide for receiving inputting signals from a signal stylus above the flat panel display. And the sensor board has a reflector surface layer for reflecting lights dispersed from a lower surface of the lightguide.

FIELD OF THE INVENTION

The present invention relates to a flat panel display (FPD) into which a digitizer is integrated, and more specifically, to a design of integrating the sensor board of the digitizer into a backlight unit and integrating the control board of the digitizer into the drive circuits of the flat panel display.

BACKGROUND OF THE INVENTION

With the advance of techniques for fabricating thin-film transistors, the flat panel displays (FPD) are widely applied in electrical products, such as PDAs, laptops, digital cameras, cell phones, etc. due to advantages as portability, non-radiation and lower power consumption. Especially when the manufacturers devote themselves to further research and improve the materials, processes and equipments, the qualities of FDP devices are promoted and the production costs thereof are reduced substantially.

In general, on these electronic products, such as PDAs or notebook, are assembled with keyboards for providing consumers to input data and orders. However, following the current design trend of the electronic products towards portable and practical, the keyboards occupied the part space of the electronic products usually hinder from the portability. Therefore, touch screens are introduced to some electronic products.

In the conventional touch screens, a touch panel is fabricated on a display to provide consumers for inputting data and orders by utilizing a hand-held stylus in conjunction with the touch screen display. However, because it is indispensable to fabricate the touch panel onto the outer surface of display, some light source is obstructed, and thus the image displaying efficiency is decreased. Even though the transparency of the touch panel in current products is promoted about 85%, for most electronic products with touch panels, the extra backlight sources are still required to provide enough illumination. And the transparency limitation of the touch panels also squander lots of electrical power.

For thoroughly solving the above problems, the display manufacturers introduce digitizers to substitute for the conventional touch screen. Please refer toFIG. 1, a liquid crystal display10integrated with a digitizer40is illustrated. The liquid crystal display10comprises a display module20, a backlight unit30and the digitizer40. The display module20has an upper glass substrate22, a lower glass substrate24, and a liquid crystal molecule layer inserted therebetween. On the upper glass substrate22an upper polarizer26is fabricated, and beneath the lower glass substrate24a lower polarizer26is fabricated. Specially, a printed circuit board assembly (PCB assembly)27is electrically connected to the lower glass substrate24via a flexible printed circuit board (FPC)29for driving the thin film transistors on the lower glass substrate24. By using a timing control chip25fabricated on the PCB assembly27, the thin film transistors can be switch on or off.

Besides, the backlight module30comprises a lightguide32, optical films34, a white sheet36, a lamp38and a reflector cover39. The lightguide32made of acrylics is applied to provide light propagating paths. Aside the lightguide32disposed the lamp38is applied to illuminate the lightguide32in the edgelight form. The lights entering from one side of the lightguide32can propagate therethrough to another side in the total reflection form. Aside the lamp38the reflector cover39is applied to prevent illumination from dissipating. The white sheet36is placed beneath the lightguide32to reflect the light dispersed from the lightguide32. And the optical films34disposed on the lightguide32including some diffuser films and brightness enhancing films are introduced to make the light scattering more uniformly.

The digitizer40comprises a sensor board42and a control board44. The sensor board42has the grid type of antenna arrays and is mounted underneath the backlight unit30. When consumers utilize a hand-held stylus to select or input data above the display module20, the sensor board42can receive the electromagnetic signals and transfer these signals to the control board44via a connecting bus46. Then the control board44can decode these signals and communicate with the motherboard of the electronic product. On the control board44an ASIC chip48is fabricated for providing the above decoding and communicating functions.

It is noted that after assembling the display module20and the backlight unit30, the FPC board29is wound around the sidewall of the backlight unit30to have the drive circuit board27attached to the lower surface of the backlight unit30for saving space. However, after integrating the digitizer40into the display, if the sensor board42is disposed under the drive circuit board27, the electronic signals passing on the drive circuit board27will severely interfere with the signals received by the antenna arrays of the sensor board42. Therefore, as shown inFIG. 2, in the current displays, the sensor board42is inserted between the drive circuit board27and the backlight unit30, and which is screwed or taped to fasten onto the backlight unit30for preventing from the signal interference of the drive circuit board27. However, after that, the thickness of the display is increasing, and thus it is indispensable to prolong the FPC board29for inserting the sensor board42between the drive circuit board27and the backlight unit30.

SUMMARY OF THE INVENTION

The primal objective of the present invention is to provide a new design of integrating the sensor board of the digitizer into the backlight unit of the flat panel display.

Another objective of the present invention is to provide a design of fabricating the sensor board with a reflector surface layer, and thus the sensor board is capable of reflecting lights.

The further objective of the present invention is to provide one single control circuit board and one single control chip for simultaneous driving the thin film transistors of the display and decoding the signals received by the sensor board.

The present invention discloses a new flat panel display which comprises the following components. A lower glass substrate is used for fabricating thin film transistors. An upper glass substrate is used for fabricating a color filter. A liquid crystal molecule layer is disposed between the upper glass substrate and the lower glass substrate. Some optical films are disposed beneath the lower glass substrate for scattering lights uniformly. A lightguide is disposed beneath the optical films for providing the paths of lights propagating. A lamp is disposed aside the lightguide for emitting lights into the lightguide in the edgelight form. A sensor board is attached beneath the lightguide for receiving signals from a hand-held stylus above the flat panel display, wherein the sensor board has a reflector surface layer for reflecting lights dispersed from a lower surface of the lightguide. And a control circuit board is attached to a lower surface of the sensor board, and is connected electrically to the lower glass substrate via a flexible printed circuit board for driving the thin film transistors. The control circuit board is also connected to the sensor board via a connecting bus for decoding the signals received by the sensor board.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Please refer toFIG. 3, a flat panel display (FPD)100in which a digitizer is integrated is illustrated. The flat panel display comprises a display module110and a backlight unit130. The display module110is fabricated on a top surface of the backlight unit130, and has the components of a lower glass substrate112for fabricating thin film transistors, an upper glass substrate114for fabricating a color filter, and a displaying molecule layer containing materials such as liquid crystal molecules (not illustrated) for forming images by the thin film transistors. In general, on the upper glass substrate114an upper polarizer plate (not shown) is fabricated, and similarly beneath the lower glass substrate112a lower polarizer plate (not shown) is fabricated for adjusting phases of lights and promoting the usage efficiency of lights.

Besides, the backlight unit130beneath the display module110comprises a lightguide132, a sensor board134, a lamp136and a reflector cover138. The lightguide132is applied to provide lights propagating paths. And the lamp136aside the lightguide132is applied to emit lights into the lightguide132in the edgelight form. The lights entering the lightguide132can propagate therethrough in the total reflection form and emit uniformly from a top surface of the lightguide132. The reflector cover138disposed around the lamp136is applied to reflect and concentrate lights for promoting the amount of lights entering the lightguide132.

In general, on the lightguide132a plurality of optical films (not shown) are fabricated to make the lights emitted from the top surface of the lightguide scatter uniformly. When the backlight unit130is assembled with the display module110, the optical films are attached to a lower surface of the display module110. In a preferred embodiment, the optical films comprise upper diffuser films, brightness enhancing films, and lower diffuser films. The upper and lower diffuser films are used for scattering lights uniformly. And the brightness enhancing films, such as the BEFs made of prisms or the DBEFs (Dual Brightness Enhanced Film) made of polarizers, are used for condensing lights.

Furthermore, the sensor board134is attached to a lower surface of the lightguide132for receiving inputting signals from a hand-held stylus above the flat panel display. In a preferred embodiment, the sensor board has a thickness of 0.40˜0.8 mm and comprises an antenna array layer and a reflector surface layer. The antenna array layer is made of FR4or FPC materials and has a thickness of 0.2˜0.4 mm for receiving electro-magnetic signals from the hand-held stylus. And the reflector surface layer has a thickness of 0.2˜0.4 mm and can be formed on or beneath the antenna array layer basing process requirements to reflect the lights dispersed from the lower surface of said lightguide132.

A control circuit board116is fabricated under the backlight unit130to control the thin film transistors on the lower glass substrate112and to decode the signals received by the sensor board134. As shown asFIG. 3, the control circuit board116is mounted on a lower surface of the sensor board134, and is connected to the lower glass substrate112for driving the thin film transistors thereon via a flexible printed circuit board118. The flexible printed circuit board118connected to the lower glass substrate112is wound downward and around sidewalls of the lower glass substrate112and the backlight unit130to connect with the control circuit board116. And the control circuit board116is also connected with the sensor board134via a connecting bus120for decoding the signals received by the sensor board134.

It is noted that an integrated control chip122is mounted onto the control circuit board116for executing the functions of driving the thin film transistors and decoding the signals from the sensor board. Namely the integrated control chip122is introduced to provide timing control signals for driving and controlling the thin film transistors, and simultaneously to provide logical functions of decoding and delivering signals from the sensor board134.

The flat panel display with a digitizer provided in the present invention has some advantages as follows:

First, because the sensor board of the digitizer is integrated into the backlight unit, the display device will have a small thickness than that in the prior art. And the material of the reflector surface layer will not affect the efficiency of receiving signals of the sensor board. So even though the sensor board is fabricated with the reflector surface layer, its capability of detecting the signals from the hand-held stylus can be still maintained.

Second, it is not required to use the screws or tapes to fasten the sensor board when it is assembled to the backlight unit. Therefore, in the later procedures of fabricating the control circuit board, the appearance of the display device will be more planar, and the reliability thereof will be more stable. And because the sensor board is fastened in the casing of the backlight unit, the joint compatibility between the sensor board and the display module is better. Especially, the displacement of the sensor board which is screwed or taped for fixing in the prior art can be effectively avoided by applying the design of the present invention effectively. Namely the alignment of the sensor board can be more accurate because the sensor board is disposed in the casing of the backlight unit.

Besides, the control board of the digitizer and the drive circuit board for driving the thin film transistors in the prior art are both integrated in one single control circuit board in the present invention. And similarly the ASIC chip and the timing control chip are both integrated into one single control chip. So no extra circuit board and connecting bus are used in the present invention, and thus the electronic products can be manufactured more portable and the prime cost can be further reduced.

Please refer toFIGS. 4 & 5, these FIGUREs illustrate the difference between of the conventional display and the new display of the present invention in their top views. InFIG. 4, a sensor board42is attached to a lower surface of the backlight unit by screws or tapes. And the above drive circuit board27and the control board44are fabricated on the sensor board42. On the drive circuit board, a timing control chip25is mounted and connected to the thin film transistors in the display module via a flexible printed circuit board29. And a connecting slot23is also fabricated on the drive circuit board for connecting to the system motherboard. Further, on the control board44fabricated is an ASIC chip which is connected to the sensor board42via a connecting bus49and connected to the system motherboard via another connecting bus51.

Compared to the conventional flat panel display, in the top view of the flat panel display provided by the present invention as shown inFIG. 5, the sensor board134is fabricated in the casing of the backlight unit. Similarly, beneath the backlight unit a control circuit board116is fabricated and connected to the thin film transistors of the display module via the flexible printed circuit board118. And because the control circuit board116is also applied to decode signal from the sensor board134, one connecting bus120is introduced to connect the control circuit board116and the sensor board134. Besides, as aforementioned, the integrated control chip122is mounted onto the control circuit board116to execute the functions of driving the thin film transistors and decoding the signals from the sensor board. And another connecting bus123is applied to connect the control circuit board116and the system motherboard.

As is understood by a person skilled in the art, the foregoing preferred embodiment of the present invention is illustrated of the present invention rather than limiting of the present invention. It is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims, the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar design.