2D/3D switchable and touch sensitive display and method for driving the same

A 2D/3D switchable and touch sensitive display, comprising a display panel with a plurality of pixels and a LC cell is disclosed. The LC cell is disposed on the display panel for providing 2D/3D switchable and touch sensitive function. The LC cell comprises a first substrate and a second substrate opposite to each other, a plurality of first electrodes disposed on the first substrate, a plurality of second electrodes disposed on the second substrate, and a liquid crystal layer disposed between the first electrodes and the second electrodes. The second electrodes interlaced with the first electrodes. The liquid crystal layer is controlled by a voltage between the first electrodes and the second electrodes for adjusting light path from the display panel and/or touch sensing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates in general to a 2D/3D switchable display and method for driving the same, and more particularly to a touch sensitive 2D/3D switchable display and method for driving the same.

2. Description of the Related Art

As technology develops, a three-dimensional (3D) image display device capable of displaying an image in 3D is developed. A 3D image is generated by the principle of stereo vision of both eyes. The different images are received by individual eyes, merged by the brain and be developed into a stereoscopic image. Naked eye three dimensional (auto-stereoscopic) technology is produced so that viewers can watch the 3D images without wearing a three dimensional glasses. The main types of naked eye 3D display are lenticular lens type and parallax barrier type. By using switchable lenticular lens or switchable parallax barrier, a 2D/3D switchable display can be achieved so that viewers can optionally watch 2D or 3D images according to their preference.

Also, touch sensitive panel technologies are developed rapidly these years. The screens of a smart-phone and a tablet PC are integrated with a touch sensor for detecting touch information. However, the combination of the 3D and touch sensitive functions is difficult due to the manufacturing complexity and the problems of heaviness. Besides, a 2D/3D switchable display with an additional touch panel may be too thick to be accepted by the consumers.

SUMMARY

The invention is directed to a 2D/3D switchable and touch sensitive display and method for driving the same. The 2D/3D switchable and touch sensitive display having a LC cell disposed on the display panel for providing 2D/3D switchable and touch sensitive function.

According to a first aspect of the present invention, a 2D/3D switchable and touch sensitive display, comprising a display panel with a plurality of pixels and a LC cell is disclosed. The LC cell is disposed on the display panel for providing 2D/3D switchable and touch sensitive function. The LC cell comprises a first substrate and a second substrate opposite to each other, a plurality of first electrodes disposed on the first substrate, a plurality of second electrodes disposed on the second substrate, and a liquid crystal layer disposed between the first electrodes and the second electrodes. The second electrodes interlaced with the first electrodes. The liquid crystal layer is controlled by a voltage between the first electrodes and the second electrodes for adjusting light path from the display panel and/or touch sensing.

According to a second aspect of the present invention, a method for driving a 2D/3D switchable and touch sensitive display. The method comprises following steps. A display panel and a LC cell disposed on the display panel is provides. The LC cell comprises a first substrate and a second substrate opposite to each other. A plurality of first electrodes are disposed on the first substrate, a plurality of second electrodes are disposed on the second substrate and interlaced with the first electrodes, and a liquid crystal layer is disposed between the first electrodes and second electrodes. Each of the first electrodes comprises a plurality of conductive lines arranged in parallel, and the conductive lines in each first electrode are electrically connected with each other. A display panel displays an image. The LC cell is driven by providing a voltage between the first and second electrodes for controlling the liquid crystal layer to adjust a light path from the display panel and/or sensing a touch information.

DETAILED DESCRIPTION

FIG. 1illustrates a cross section view of a 2D/3D switchable and touch sensitive display10according one embodiment of the invention. Referring toFIG. 1, a 2D/3D switchable and touch sensitive display10comprises a liquid crystal (LC) cell11and a display panel12. The LC cell11disposed on the display panel12comprises a first substrate102, a first electrode layer104a, a liquid crystal layer106, a second electrode layer104band a second substrate108opposite to the first substrate102. The LC cell11may comprise additional optical function layer, like polarizer or phase retarder, between the observer and the liquid crystal layer106for modulating the light transmittance or phase. The LC cell11for example is a passively driven type or active driven type switchable lens or switchable barrier. The material of the first substrate102and the second substrate108could be glass, plastic or other transparent organic polymers. The material of the first electrode layer104aand the second electrode layer104bcould be transparent conductive metal oxide (ITO, IZO), metal or alloy.

The first electrode layer104acomprises a plurality of first electrodes disposed on the first substrate102, and a second electrode layer104bcomprises a plurality of second electrodes disposed on the second substrate108. The second electrodes are interlaced with the first electrodes. The liquid crystal layer106is disposed between the first substrate102and second substrate108. Actually, the liquid crystal layer106is disposed between the first electrode layer104aand the second electrode layer104b. The liquid crystal layer106is controlled by a voltage difference between the first electrode layer104aand the second electrode layer104bfor adjusting the path or phase while a light passing through the display panel12. Additionally, the lamination of the first substrate102and the second substrate108could be misplaced to expose the first electrode layer104a(down) and the second electrode layer104b(up) for bonding from two interlace directions.

In this embodiment, the 2D/3D switchable and touch sensitive display10can display a two view 3D image, since a gap between two adjacent first electrodes of the first electrode layer104acorresponds to two pixels (unit dot of image) of the display panel12and the two pixels playing two images with parallax. In other embodiments, the 2D/3D switchable and touch sensitive display10can also be a multi-view display when displaying a plurality of images with parallax if a gap between two adjacent first electrodes corresponds to more pixels. The pitch of two adjacent first electrodes corresponding to at least two pixels of the display panel12. The better choice of the pitch is corresponded to even number of pixels.

The display panel12such as a LCD or an organic light-emitting diode (OLED) is used for displaying and providing an image. If the display panel12is a LCD, then it can comprises polarizer112, substrate114, color filter (CF) and thin-film transistor (TFT)116, substrate118, polarizer120and liquid crystal (not shown inFIG. 1). The structure of the invention is not limited thereto. The display panel12can be assembly and fixed with the LC cell11by glue110or other adhesives.

FIG. 2Aillustrates a diagram of electrode layers in a 2D/3D switchable and touch sensitive display10according one embodiment of the invention. Referring toFIG. 2A, the first electrode layer104acan comprises a plurality of first electrodes R1, R2, R3, R4and R5. Each of the first electrodes R1˜R5comprises a plurality of conductive lines1040arranged in parallel, and the conductive lines1040in each first electrode R1˜R5are electrically connected with each other in a group by a conductive pad1042at an end of the conductive line1040. The number of the first electrodes and the conductive lines depends on driving ability of IC, driving scheme of sensing process, RC loading, and 3D function.

The second electrodes T1, T2, T3, T4and T5are horizontal stripe electrodes. The conductive lines1040of the first electrodes R1˜R5are substantially vertical to the second electrodes T1˜T5. A width of the conductive line1040is smaller than a width of one of the second electrodes T1˜T5. InFIG. 2A, merely five first electrodes and five second electrodes are illustrated to simplified the structure for sake of clarity, and the invention is not limited thereto.

In one embodiment for displaying an image with HD 720 resolution, a number of first electrodes can be 20 and each first electrode comprises 32 conductive lines1040. Besides, a number of the second electrodes can be 12. In this case, the touch sensor electrodes arrange in a M by N matrix, M for example is 20 and N for example is 12. The number of the first electrodes and the second electrodes are adjustable according to the size, the resolution and the sensitivity of the 2D/3D switchable and touch sensitive display10.

Each pair of the first electrode and the second electrode separated by a dielectric layer (liquid crystal layer106) for forming a capacitance called touch sensitive unit. Several touch sensitive units form a touch sensitive screen. While a charge disturbance of the electrode, the change can be detected and transfer to a touch signal. In one embodiment, the first electrodes R1˜R5can be used as receivers of a touch sensor and the second electrodes T1˜T5can be used as transmitters of the touch sensor, and the invention is not limited thereto. In other embodiment, the first electrodes R1˜R5can be used as transmitters of a touch sensor and the second electrodes T1˜T5can be used as receivers of the touch sensor. Each first electrode R1˜R5or each second electrode T1˜T5can be driven sequentially for sensing a touch information. Moreover, the conductive lines1040of the first electrodes R1˜R5or the second electrodes T1˜T5can be driven at the same time to form a switchable barrier or a switchable lens for adjusting a light path of light transmitting from the display panel.

FIGS. 2B˜2Cshows diagrams of electrode layers in a 2D/3D switchable and touch sensitive display10according other embodiments of the invention. Referring toFIG. 2B, the conductive lines1044of the first electrode layer104aare substantially parallel to each other, and the conductive lines1044of the first electrode layer104aare orthogonal to the second electrodes1046. Referring toFIG. 2C, the conductive lines1044of the first electrode layer104aare substantially parallel to each other, conductive lines1044of the first electrode layer104aare slant to the second electrodes1048. The arrangements of the electrodes are so-called a slant lens design and can reduce the 3D moiré and solve the color shift issue by misalignment with the pixel alignment of the display panel12.

The 2D/3D switchable and touch sensitive display10can be driven by different signals in various embodiments of the invention. The driving method of the 2D/3D switchable and touch sensitive display10are described as follows.

First Embodiment

FIG. 3Aillustrates a waveform diagram of driving signals for driving a 2D/3D switchable and touch sensitive display in a 3D mode according to an embodiment of the invention. Referring toFIGS. 2A and 3A, a DC signal Rx (such as 0V) is inputted to the first electrodes R1˜R5, and alternative signals (AC) T10, T20, T30. . . T50with the same duty cycle are respectively inputted to the second electrodes T1˜T5. The DC signal Rx inputted synchronous (in phase) to the first electrodes R1˜R5and the alternative signals T10, T20, T30. . . T50inputted synchronous (in phase) to the second electrodes T1˜T5. The alternative signals are pulse (or square, sine) signals. The numbers of the DC signal Rx and that of the alternative signals T10, T20, T30. . . T50correspond to the numbers of the second and first electrodes.

Each of the alternative signals T10, T20T30. . . T50can be a superposition of a first signal S10and a second signal S20. The first signals S10are pulse (or square, sine) signals and the voltage difference is between the amplitude difference (modulus) of the first signals S10and the DC signals. In a 3D mode, the first signal S10can have amplitude of ±5V, with the same duty cycle, and synchronous (in phase) in a frequency of 60 Hz to switch on the liquid crystal layer106(shown inFIG. 1) for producing the switchable lens and switchable barrier, so that the 2D/3D switchable and touch sensitive display10can display 3D images. Besides, the second signal S20(or square, sine) can have an amplitude of ±αV, with the same duty cycle, and sequentially in a frequency of 120 Hz for touch sensing, and α is much less than 5. In addition, the modulus of the first signals S10and the second signals S20are positive integer, and the modulus of the first signals S10are larger than that of the second signals S20. The doubled frequency of the second signals S20in a frame (a pulse of the first signals) using a pair of a positive signal and a negative signal for reducing the disturbing switchable lens or switchable barrier function. The second signals S20are separated from each other for touch sensing.

As shown inFIG. 3A, the alternative signals T10, T20and T30. . . T50have a period of 16.7 ms. The second electrodes T1˜T5driven by the first signal S10having the same period with the alternative signals T10, T20and T30. . . T50can control the liquid crystal layer106to form a switchable lens or a switchable barrier. The second electrodes T1˜Tn are sequentially driven by the second signals S20with short period such as 2-3 μs and the first electrodes R1˜R5are biased with DC voltage source, and the DC-biased first electrodes R1˜R5can receive small voltage changes by finger touch.

FIG. 3Billustrates a waveform diagram of driving signals for driving a 2D/3D switchable and touch sensitive display in a 2D mode according to an embodiment of the invention. Referring toFIGS. 2A and 3B, a DC signal Rx (such as 0V) is inputted to the first electrodes R1˜R5, and alternative signals T12, T22, T32. . . T52are respectively inputted to the second electrodes T1˜T5. The DC signal Rx and the alternative signals T12, T22and T32. . . T52are interchangeable.

Each of the alternative signals T12, T22and T32can be a superposition of a first signal S10and a second signal S20. In a 2D mode, the first signal S10can have amplitude of 0V (less than the threshold voltage of the liquid crystal layer106and more than or equal to 0V) so that the switchable lens and switchable barrier are switched off to display 2D images. Besides, a second signals S20can have an amplitude of ±αV and a frequency of 120 Hz, the waveforms of the second signals S20in 2D and 3D modes are the same. In other embodiment, the frequency of the second signals can be reduced to 60 Hz, since a number of interlaced positive and negative second signals S20in 2D mode can be reduced to half of the number of that in 3D mode, for disturbing the functions of switchable lens or switchable barrier. As shown inFIGS. 2A and 3B, the second electrodes T1˜T5are sequentially driven by the alternative signals T12, T22, T32. . . T52with short period such as 2-3 μs and the first electrodes R1˜R5are biased with DC voltage source, and the first electrodes R1˜R5can receive small voltage changes by finger touch.

Second Embodiment

FIG. 4Aillustrates a waveform diagram of driving signals for driving a 2D/3D switchable and touch sensitive display in a 3D mode according to another embodiment of the invention. Referring toFIGS. 2A and 4A, a DC signal Rx (such as 0V) is inputted to the first electrodes R1˜R5, and alternative signals T11, T21, T31. . . T51are respectively inputted to the second electrodes T1˜T5. The DC signal Rx inputted to the first electrodes R1˜R5and the alternative signals T11, T21and T31. . . T51respectively inputted to the second electrodes T1˜T5are interchangeable.

In a 3D mode, the alternative signals (square, pulse or sine wave) T11, T21and T31. . . T51can be a superposition of a first signal S11(the position and half cycle of first signal S11is illustrated inFIG. 4B) and a second signal S21(illustrated inFIG. 4B). The alternative signals T11, T21and T31. . . T51have an amplitude of ±5V, a frequency of 60 Hz and the same duty cycle, so that the switchable lens and switchable barrier are switched on to display 3D images. Besides, the second electrodes T1˜T5are sequentially driven by the alternative signals T11, T21and T31. . . T51and the first electrodes R1˜R5are biased with DC voltage source, the DC-biased first electrodes R1˜R5can receive small voltage changes by finger touch. The waveform patterns of the DC signals Rx and the alternative signals T11, T21and T31. . . T51applied to the first and second electrodes can be utilized to both form the switchable barrier or the switchable lens and detect touch information. The alternative signals T11, T21and T31. . . T51are arranged with a shift to each other (non-synchronous).

FIG. 4Billustrates a waveform diagram of driving signals for driving a 2D/3D switchable and touch sensitive display in a 2D mode according to an embodiment of the invention. Referring toFIGS. 2A and 4B, a DC signal Rx (such as 0V) is inputted to the first electrodes R1˜R5, and alternative signals T12, T22and T32are respectively inputted to the second electrodes T1˜T5. The DC signal Rx and the alternative signals T13, T23, T33. . . T53are interchangeable.

In a 2D mode, the first signals S11having an amplitude of 5V is turned off to switch off the switchable lens and switchable barrier so that the 2D/3D switchable so that the touch sensitive display10can display 2D images. Besides, second signals S21having an amplitude of ±βV (such as ±5V) and a frequency of 60 Hz (square, pulse or sine wave) can be applied to the second electrodes T1˜T5. As shown inFIGS. 2A and 4B, the second electrodes T1˜T5sequentially driven by the another first signals T13, T23, T33. . . T53with short period such as 2-3 μs, and the first electrodes R1˜R5are biased with DC voltage source to receive small voltage changes by finger touch. In this embodiment, the modulus of the alternative signals and the β are the same (positive integer).

Third Embodiment

FIG. 5Aillustrates a waveform diagram of driving signals for driving a 2D/3D switchable and touch sensitive display in a 3D mode according to an embodiment of the invention. Referring toFIGS. 2A and 5A, alternative signals Rx comprise first signals S13is inputted to the first electrodes R1˜R5, and another alternative signals T14, T24, T34. . . T54comprise second signals S13with the same duty cycle are sequentially inputted to the second electrodes T1˜T5. The alternative signals Rx inputted to the first electrodes R1˜R5and the another alternative signals T14, T24, T34. . . T54respectively inputted to the second electrodes T1˜T5are interchangeable.

In a 3D mode, the alternative signals Rx can have amplitude of ±5V and a frequency of 60 Hz, and the switchable lens and switchable barrier are switched on so that the 2D/3D switchable and touch sensitive display10can display 3D images. Besides, another alternative signals T14, T24, T34. . . T54with the same duty cycle can have an amplitude of ±αV and a frequency of 120 Hz, and α is much less than 5. The alternative signals Rx can have a period of 16.7 ms. (the definition of α is the same with that in embodiment 1)

The first electrodes R1˜R5driven by the alternative signals Rx (first signal S13) can control the liquid crystal layer106to form a switchable lens or a switchable barrier. The second electrodes T1˜T5are sequentially driven by the another alternative signals T14, T24, T34. . . T54(second signal S13) with short period such as 2-3 μs, and the first electrodes R1˜R5can be connected to an input end of an Operational Amplifier (Op-Amp) and be virtually biased with DC voltage source to cancel the LC driving voltage impact. The virtually DC-biased first electrodes R1˜R5can receive small voltage changes induced by finger touch.

FIG. 5Billustrates a waveform diagram of driving signals for driving a 2D/3D switchable and touch sensitive display in a 2D mode according to an embodiment of the invention. Referring toFIGS. 2A and 5B, a DC signal Rx (such as 0V) is inputted to the first electrodes R1˜R5, and second signals T15, T25, T35. . . T55are sequentially and respectively inputted to the second electrodes T1˜T5. The DC signal Rx and the second signals T15, T25and T35. . . T55are interchangeable.

In a 2D mode, the switchable lens and switchable barrier are switched off (first signal S13is turned off) so that the 2D/3D switchable and touch sensitive display10can display 2D images. Besides, the second signals can have an amplitude of ±αV and a frequency of 120 Hz can be inputted to the second electrodes T1˜T5. The second electrodes T1˜T5sequentially driven by the another alternative signals T15, T25and T35. . . T55(second signals S23) with short period such as 2-3 μs, and the first electrodes R1˜R5are biased with DC voltage source to receive small voltage changes induced by finger touch. In other embodiment, the frequency of the second signals can be reduced to 60 Hz, since a number of interlace positive and negative second signals S23in 2D mode can be reduced to half of the number of that in 3D mode, for disturbing the functions of switchable lens or switchable barrier function.

FIG. 6illustrates a simplified equivalent circuit of a simplified 2D/3D switchable and touch sensitive display according to an embodiment of the invention. As shown inFIG. 6, the equivalent circuit comprises a buffer to provide a voltage source for driving a transmitter electrode T with a step voltage. A mutual capacitance between the transmitter electrode T and the receiver electrode R can be measured for touch detecting.

The receiver electrode R is connected to an Operational Amplifier (Op-Amp)302so that current from the receiver electrode R passes through an Op-Amp. The Op-Amp302coupling with a capacitance C is used as charge integrator. Since the charge received by the charge integrator can be converted to a voltage signal, a detected touch signal S1and an untouched signal S2can be distinguished. Then, the detected touch signal S1and an untouched signal S2can be digitized by an analog-to-digital converter (ADC) element for signal processing in MPU. In this circuit, since the receiver electrode R is virtually connected to a DC bias voltage source (can be virtual ground) of the charge integrator, the LC driving voltage impact can be canceled and the receiver electrode R can receive small voltage change by finger touch.

Based on the above, the embodiments of the invention provide a 2D/3D switchable and touch sensitive display. The 2D/3D switchable and touch sensitive display combines the 2D/3D switchable techniques and touch sensing techniques together and integrates electrodes for controlling the liquid crystal layer to form a 2D/3D switchable lens (or barrier) and electrodes for touch sensing in one liquid crystal cell. The 2D/3D switchable and touch sensitive display has advantages such as thin size, light weight, low cost and simple manufacturing procedure. Besides, the 2D/3D switchable and touch sensitive display can be manufactured simply and without additional photo-mask process by using the electrodes as the receiver and transmitter of a touch sensor and as a switch for LC lens (or barrier) control.