JP2004519718A - Display device with switchable semi-transmissive reflective part and visible on both sides - Google Patents

Abstract

An apparatus and / or method for providing a transflective unit having a reflective state and a transmissive state to an LCD device (10). Either two transflectors (12, 20) are provided to form a device having double-sided display, or one transflector (68) provides a display having a display state and a transmission state. Used to

Description

[0001]
(Technical field)
The present invention relates generally to display devices, and more particularly, to an apparatus and method for providing a display with a transflective unit that can select between a reflective state and a transmissive state.
[0002]
(Background technology)
2. Description of the Related Art Liquid crystal displays (hereinafter referred to as LCDs) are generally used as display devices in devices such as portable televisions, notebook computers, mobile phones, and other portable electronic devices. A conventional LCD includes a plurality of LCD elements forming a plurality of rows and columns, and each LCD includes a pixel (pixel) electrode and a common electrode sandwiching a liquid crystal material portion therebetween. Further, the conventional LCD uses a reflection mode that requires a predetermined minimum ambient light intensity in order to obtain a sufficient contrast ratio at the time of display so that a viewer can sufficiently identify the display.
[0003]
More generally, a conventional LCD includes an upper polarizer, an upper substrate, an upper electrode, a liquid crystal, a lower electrode having a predetermined pattern or arrangement, a lower substrate, a lower polarizer, and a reflector (semi-transmissive reflection). It has a layered assembly. The polarizers are arranged on orthogonal axes in a mutually orthogonal relationship. The operating principle of LCDs is well known in the art. One such principle is to operate an LCD by applying an electric field to reduce the light transmission through a thin layer of liquid crystal material.
[0004]
Many conventional LCDs use a reflector or transflector on an opaque background plate that only functions in a reflective state. Some conventional LCDs, including some watches, operate in a transmissive mode with a transparent background. Also, conventional LCDs are readable only on one side. Thus, information that needs to be displayed on a device that is closed when not in use, such as a mobile phone, can only be displayed by providing another alternative display having circuitry to operate the display. Other alternative displays and additional circuitry can be prohibitively expensive, both in cost and size.
[0005]
(Disclosure of the Invention)
The present invention relates to an apparatus and / or method for providing a transflective unit having a reflective state and a transmissive state to an LCD device. Two transflectors are provided to form a device with double-sided display, or one transflector can be used to display a display state and a transmissive state. Although the following description, which is one aspect of the present invention, relates primarily to portable communication devices, it is also understood that the devices and / or methods of the present invention may be implemented in connection with implementing other forms of display. It will be understood and obvious to the trader.
[0006]
FIG. 1 shows a block diagram of a side view of a display 10 with both sides visible according to one embodiment of the present invention. The display 10 whose both sides can be viewed has a first semi-transmissive reflective portion 12 provided on the first surface side of the LCD cell 14 and a second semi-transmissive reflective portion 20 provided on the second surface side of the LCD cell 14. The first polarizer 13 is disposed between the first semi-transmissive reflector 12 and the first surface of the LCD cell 14, and the second polarizer 18 is arranged between the second semi-transmissive reflector 20 and the second It is arranged between the surface sides. The LCD cell 14 includes a liquid crystal layer 16 of, for example, a twisted nematic (TN) type sandwiched between a first electrode 15 and a second electrode 17. The first and second electrodes 15, 17 both include a transparent electrode pattern or arrangement. The first and second polarizers 13 and 18 are used to deflect ambient light passing through the polarizers 13 and 18 in the X and Y directions. Since the use of polarizers in twisted nematic and super twisted nematic (STN) LCD devices is well known to those skilled in the art, further description of polarizers 13 and 18 is omitted to avoid complication. I do.
[0007]
The transflective portions 12 and 20 can be formed from, for example, an electrochromic material or a liquid crystal material in which a polymer is dispersed. An electrochromic material or a polymer dispersed liquid crystal material can be used to obtain cells that are in one of a substantially transparent state or a reflective semi-opaque state. These types of cells can change color by applying a voltage to the cell. Taking an electrochromic cell (EC) as an example, when no voltage is applied to the cell, the cell is optically transparent. When a DC voltage is applied to the cell, the cell changes to a reflective, semi-opaque color state. The electrochromic cell can be selected to obtain a transparent state and a colored state, the color exhibiting one of blue, green, black and white. Further, cells for changing colors may be stacked to obtain a multi-color transflective portion.
[0008]
In one embodiment of the present invention, a white electrochromic cell is used for each of the transflective portions 12 and 20. The LCD cell 14 is sandwiched between the polarizing plates 13 and 18 and the transflectors 12 and 20. When a voltage V ₁ ⁺ is applied to the first semi-transmissive reflector 12 instead of the second semi-transmissive reflector 20, the first semi-transmissive reflector 12 becomes semi-opaque and reflective, and the second semi-transmissive reflector 20 becomes transparent. And become transparent. Therefore, the incident light that has passed through the second transflective unit 20 is reflected backward by the first transflective unit 12, and the LCD cell 14 can be visually recognized through the second transflective unit 20. Alternatively, when the voltage V ₂ ⁺ is applied to the second semi-transmissive reflector 20 instead of the first semi-transmissive reflector 12, the second semi-transmissive reflector 20 becomes semi-opaque and reflective, and the first semi-transmissive reflector becomes 12 becomes transparent. Therefore, the incident light that has passed through the first transflective unit 12 is reflected backward by the second transflective unit 20, and the LCD cell 14 can be viewed through the first transflective unit 12.
[0009]
FIG. 2 shows an example in which a display that can be viewed from both sides is applied to the portable communication device 30. The portable communication device 30 includes an upper portion 32 having a double-sided viewable display 34 having a front surface 40 and a back surface 42 (FIG. 4). The portable communication device 30 also includes a lower portion 36 having a keypad 38 for inputting information to the portable communication device 30. The portable communication device 30 has an open state as illustrated in FIG. 2 and a closed state as illustrated in FIG. When the portable communication device is in its open state, the text shown in FIG. As is evident from FIG. 3, while displaying text from the front surface 40, the first transflective unit 12 (disposed on the back) is in a semi-opaque or reflective state and the second transflective unit 20 (front surface). Is in a transparent or transmissive state. As shown in FIG. 4, when the portable communication device 30 is in the closed state, the text is displayed on the back surface 42 of the display 34 (FIG. 4). As illustrated in FIG. 5, while displaying text from the front surface 42, the second transflective unit 20 is in a semi-opaque or reflective state and the first transflective unit 12 is in a substantially transparent or transmissive state. It is in.
[0010]
FIG. 6 shows an example of a drive scheme 50 used to provide a similar display on either the front 40 or the back 42 of the duplex display 34. The LCD drive circuit element 58 outputs a drive signal to the drive inversion element 56 and the drive selection element 54 to output a drive signal to the LCD cell on the double-sided display 34. The drive inversion element 56 outputs an inversion and synchronization signal to display characters and illustrative contents on the back surface 42 of the display 34, and when the LCD drive circuit element 58 outputs a drive signal directly to the double-sided display 34, Similarly, it is displayed on the front surface 40. The inversion drive signal preferably uses a logic circuit such as a programmable logic device (PLD), but may alternatively be implemented with unique program instructions or the like. The inversion drive signal is inverted on two axes instead of one axis, as used in mirror reflectors. The output of the inversion drive signal from the LCD drive circuit 58 can be easily realized by those skilled in the art.
[0011]
The LCD drive circuit signal and the inverted LCD drive circuit signal are both input to the drive selection element 54. The drive selection element 54 switches between the drive circuit signal output to the double-sided display 34 and the inverted drive circuit signal output according to the state of the display position switch 52. The display position switch 52 switches the state of the portable communication device between an open state and a closed state. The display position switch 52 is coupled to the double-sided display 34, and which of the transflective portions 12 and 20 is translucent to reflect (potential applied) and which is substantially transparent to view. (No potential is applied).
[0012]
In one embodiment of the present invention, the double-sided display 34 switches the transflective portions 12 and 20 and simultaneously switches between the drive input signal and the inverted drive input signal, so that images and / or characters are displayed on both sides of the display 34. Contents can be displayed. For example, by inputting a rectangular wave signal in the range of 250 to 350 Hz to the output of the display position switch 52, both sides of the display 34 can be visually recognized simultaneously. The alternating signal switches the first semi-transmissive reflector 12 alternately between a semi-transparent and substantially transparent state, while the second semi-transmissive reflection 20 alternates between a transparent and a semi-opaque state. Make it possible. The alternate switching signal multiplexes the drive input signal and the inverted drive input signal through the drive selection element 54.
[0013]
In another aspect of the invention, a single transflector is used to obtain a display having a display state and a substantially transparent transmission state. An example of this type of implementation might be to find potential application in retail markets such as jewelry stores where information about the product is visible in display and the product itself may be visible in transparent transparency. Absent. Referring to FIGS. 7 and 8, a single-sided display 60 in which an LCD cell 64 is sandwiched between a first polarizing plate 62 and a second polarizing plate 66 is shown. A single transflector 68 is disposed on one side of LCD cell 66. The single transflective portion 68 can be formed from an electrochromic material or a liquid crystal material in which a polymer is dispersed. An electrochromic material or a polymer dispersed liquid crystal material can be used to obtain cells that are in one of a substantially transparent state or a reflective semi-opaque state. Such a single transflector 68 can apply a voltage to the cell to change color. Taking an electrochromic cell as an example, the cell is optically transparent when no voltage is applied to the cell. When a DC voltage is applied to the cell, the cell changes to a reflective, semi-opaque color state. The electrochromic cell can be selected to obtain a transparent state and a colored state, the color being one of blue, green, black and white. Further, cells for changing colors may be stacked to obtain a multicolor transflective portion.
[0014]
In one embodiment of the present invention, a white electrochromic cell is used for the transflector 68. In the transparent state where the voltage V ₃ ⁺ is not applied as shown in FIG. 7, the light beam can pass through the front and back surfaces of the single-sided display 60 to obtain a transparent view of one or more objects on the opposite side of the display. Yes, in other words, the display becomes a transparent window. In the opaque state with the voltage V ₃ ⁺ applied, as shown in FIG. 8, the light rays pass through the front surface but do not pass through a single single-sided display, and the rearward display of the LCD cell 64 to display the generated image. Is reflected by
[0015]
In view of the structure described above with respect to FIGS. 1-8, the method of using transflective in an LCD device having a state in which transflective is selectable between a reflective state and a transmissive state is illustrated in FIGS. Will be better understood. 9 and 10 are shown to avoid complicating the description, and a series of processes will be described. However, according to the present invention, some processes are different from the order shown and described in the present specification. It should be appreciated and understood that the invention is not limited to the order of processing, as it may occur simultaneously with and / or with other processing. Further, not all illustrated processes may be required to implement a methodology in accordance with an aspect of the present invention.
[0016]
With reference to FIG. 9, a method of operating the double-sided display shown in FIGS. 1 to 6 will be described. The method begins at operation 100 where power is applied to a device having a two-sided display. In operation 110, the device determines whether the device has been driven to the first state. For example, the first state means that the portable communication device is in an open state as illustrated in FIG. 2, while the second state means that the portable mobile communication device is in its closed state. If the apparatus is in the first state, that is, if “YES”, a voltage is applied to the first semi-transmissive reflector so as to be visible from the first side of the double-sided display in step 120, No voltage is applied to the transflector. In process 130, an LCD drive signal is output to the LCD cell. Thereafter, at process 140, the device continuously monitors whether the device is still in the first state. If the device is no longer in the first state, ie, “NO” in either process 110 or process 140, the device enters the second state and proceeds to process 125. In process 125, the device applies a voltage to the second semi-transmissive reflector and stops applying a voltage to the first semi-transmissive reflector so that the second semi-transmissive reflector can be viewed from the second surface side. Thereafter, in process 135, an inverted LCD drive signal is output to the LCD cell. Thereafter, at operation 145, the device continuously monitors whether the device is in the second state. If the device is not in the second state, i.e., "No", the device moves to the first state and the device proceeds to operation 120; otherwise, the device remains in the second state.
[0017]
With reference to FIG. 10, a method of operating the single-sided display shown in FIGS. The method begins at process 200 where power is applied to a device having a single-sided display. In operation 210, the device determines whether the device has been driven to the first state. For example, the first state provides information related to a product whose single-sided display is directly below the single-sided display as illustrated in FIG. 8, and the second state refers to information directly below the single-sided display as illustrated in FIG. 7. The single-sided display provides a transparent window for viewing the product at When the device is in the first state, that is, in the case of "yes", a voltage is applied to the transflective portion in process 220 so that the information on the single-sided display can be visually recognized. In process 230, an LCD drive signal is output to the LCD cell. Thereafter, at process 240, the device continuously monitors whether the device is still in the first state. If the device is not in the first state, i.e., "No" in either process 210 or process 240, the device enters the second state and proceeds to process 225. In operation 225, the apparatus stops applying the voltage to the transflector so that the product on the opposite side of the single-sided display can be clearly seen. In step 235, the LCD drive signal output is invalidated. Thereafter, at operation 245, the device continuously monitors whether the device is in the second state. If the device is not in the second state, i.e., "No", the device moves to the first state and the device proceeds to operation 220; otherwise, the device remains in the second state.
[0018]
The above description includes one or more examples of the present invention. Of course, it is not impossible to describe every conceivable combination of elements and methods to describe the invention, but those of ordinary skill in the art will recognize many other combinations and permutations of the invention. You will recognize that. Accordingly, the present invention is intended to embrace all such modifications, changes and variations that fall within the spirit and scope of the appended claims. Further, in any of the detailed description or claims, as to the scope of the use of the term “comprises” and its variations, and the scope of “comprising” and its variations, such terms are to be treated as inclusive of the term “comprising” It is intended as a religion.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram of a side view of a two-sided display according to one aspect of the present invention.
FIG. 2 is a front view of an open portable communication device using double-sided display according to one aspect of the present invention.
FIG. 3 is a functional block diagram of elements used to view the display content of the front display of the portable communication device of FIG. 2 in an open state according to one aspect of the present invention.
FIG. 4 is a front view of the portable communication device of FIG. 2 in a closed state using two-sided display according to one aspect of the present invention.
FIG. 5 is a functional block diagram of an element used for visually recognizing display contents of a back surface display of the portable communication device of FIG. 2 in a closed state according to one embodiment of the present invention.
FIG. 6 is a schematic block diagram of a drive system used to drive a two-sided display according to one aspect of the present invention.
FIG. 7 is a schematic block diagram of a side view of a one-sided display in a transmissive state according to one aspect of the present invention.
FIG. 8 is a schematic block diagram of the one-sided display of FIG. 7 in a reflective state according to one aspect of the present invention.
FIG. 9 is a flowchart illustrating one particular method for displaying display content on the front or back of a two-sided display according to one aspect of the present invention.
FIG. 10 is a flowchart illustrating one particular method for displaying a single-sided display content or providing a transparent window in accordance with one aspect of the present invention.

Claims (26)

An LCD cell having a front surface and a back surface;
A first semi-transmissive reflector disposed on the front surface and switchable between a reflective state and a transmissive state;
An LCD device, comprising: a second semi-transmissive reflector layer disposed on the back surface and capable of switching between a reflective state and a transmissive state. The front surface of the LCD cell is visible when the first transflective portion is in the transmissive state and the second transflective portion is in the reflective state, and the back surface of the LCD cell layer is the second transflective portion. The device of claim 1, wherein the transflector is visible when the transflector is in a transmissive state and the first transflector is in a reflective state. The first and second transflective portions are controllable between the reflective state and the transmissive state, and a potential applied to an electrode of the corresponding transflective portion is a voltage applied to the corresponding transflective portion. 2. The device according to claim 1, wherein the device switches from a transmission state to the reflection state. The device according to claim 1, wherein the first and second transflective portions are made of an electrochromic material. The apparatus according to claim 1, wherein at least one of the first and second transflectors comprises a plurality of laminated materials for changing colors. The device according to claim 1, wherein the first and second transflective portions are made of a polymer-dispersed liquid display material. A drive inverting element capable of inverting and synchronizing a signal from an LCD drive circuit, and a second state for displaying a drive signal to the LCD cell layer in a first state for displaying the front surface of the LCD cell and a rear surface of the LCD 2. The device according to claim 1, further comprising: a selection element that can output an inverted drive signal to the LCD cell. The apparatus according to claim 7, wherein the drive inverting element inverts the drive signal on two axes. 2. The device according to claim 1, further comprising a display position switch operable to switch the device between a first state for displaying the front side of the LCD cell and a second state for displaying the back side of the LCD cell. 10. The device of claim 9, wherein the display position switch is further operable to alternate between the first state and the second state at a frequency of 250-350 Hz to simultaneously display the front and back sides of the LCD cell. The LCD device in a portable communication device, wherein the portable communication device has an open position for displaying the front surface of the LCD cell and a closed position for displaying the back surface of the LCD cell. An apparatus according to claim 1. A display position switch operable to monitor the position of the portable communication device, wherein the open position sets the LCD device to the first state, and the closed position sets the LCD device to the second state. Item 12. The apparatus according to Item 11. An LCD cell having a front surface and a back surface;
An LCD device, comprising: a semi-transmissive reflector disposed on the back surface and capable of switching between a reflective state and a transmissive state. 14. The device of claim 13, wherein the LCD device has a first state for displaying an image generated by the LCD cell and a second state for providing a transparent window. The transflective unit according to claim 13, wherein the transflective unit is in a reflective state when a potential is applied to an electrode coupled to the transflective unit, and is in a transmissive state when no potential is applied to the electrode. apparatus. 14. The device according to claim 13, wherein the transflector is made of an electrochromic material. 13. The device according to claim 12, wherein the transflector comprises a plurality of laminates for changing colors. 13. The device according to claim 12, wherein the transflective portion is made of a liquid display material in which a polymer is dispersed. Light rays pass through the front surface and are reflected by the transflective portion in the first state of displaying an image generated by the LCD cell layer, and light beams pass through the object behind the rear surface from the front surface. 13. The device of claim 12, passing through the front and back of the LCD cell in a second state where a transmissive layer is provided for viewing. 13. The apparatus according to claim 12, further comprising a position switch operable to switch the transflective portion between the reflection state and the transmission state. A portable communication device comprising the device according to claim 12. Determining the state of the LCD device;
Selecting one of the reflection state and the transmission state of the transflective unit based on the state of the LCD device;
An LCD comprising the transflective portion drivable between a reflective state and a transmissive state and comprising a transflective portion disposed on an LCD cell surface, comprising: a step of switching the transflective portion between the reflective state and the transmissive state. A method for visually confirming display contents on a device. The transflective portion includes a first transflective portion disposed on a front surface of the LCD cell, and a second transflective portion disposed on a rear surface of the LCD cell. 23. The method according to claim 22, comprising a first state of displaying the front side of the LCD cell by a transflector and a second state of displaying the rear side of the LCD cell by the second transflective part. Applying a potential to the second semi-transmissive reflector instead of the first semi-transmissive reflector in the first state, and applying the first semi-transmissive reflector instead of the second semi-transmissive reflector in the second state Applying a potential to the substrate. The method according to claim 24, further comprising outputting a drive signal to the LCD cell layer in the first state and outputting an inversion drive signal to the LCD cell layer in the second state. The first and second states are alternately switched to simultaneously display the front surface of the LCD cell through the first transflective portion and the rear surface of the LCD cell through the second transflective portion. The method of claim 25, further comprising the step of switching.

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