KR20050100625A - Touch sensitive display device - Google Patents

Abstract

A touch-sensitive display is made by incorporating a touch sensitive layer (19) between two optical layers (4, 15, 16) or between a substrate (11, 12) and a further optical layer (14, 15, 16).

Description

Touch Sensitive Display Device {TOUCH SENSITIVE DISPLAY DEVICE}

The present invention relates to a touch sensitive display device comprising a plurality of picture elements and means for applying a driving voltage to the pixels.

For example, the display device is a liquid crystal display device. Liquid crystal display devices have been found to be widely used in the computer industry and portable devices, ranging from mobile phones and price tags to palm top computers and organizers. In addition, although combinations with touching devices such as stylus and the like have been found to have a wide range of applications, there is also a need for a method of providing input through a display screen.

USP 5,777,596 discloses a touch sensitive liquid crystal display device capable of providing input to a connected device (eg, a computer, etc.) by simply touching the display screen with a finger, stylus or pen. Such a device continuously compares the charge time of a liquid crystal display element (pixel) with a reference value, and uses the comparison result to determine which element is in contact.

One of the problems with the touch sensitive liquid crystal display device is restoring the correct image after sensing. This is due to the fact that between two extreme states, a blinking line is used that represents the switching of all the pixels in one row. When such a blinking line reaches a predetermined row, the contact is detected by measuring the charging time of the pixel. After the measurement, the pixel is supplied with the appropriate voltage to display the correct image. In a similar manner, sensing using a blinking spot is disclosed in US Pat. No. 5,777,596. However, such blinking is visualized on the display (as artifacts).

Also, if a reflective display device is used, there may be internal DC bias voltages so that the charges for writing odd or even frames may be different. Since no inversion occurs in the DC driving method (low power liquid crystal display, electrophoretic display), the method can never be used in such a case.

The problem with providing blinking signals is overcome by making the spacing means (spacer) part of the means for monitoring the electrical properties of the pixel. The electrical property may be capacitive, (nonlinear) resistance or piezo-electric property. However, because locally thinner spacers may not be pressurized at all, it is necessary to configure (nonlinear) resistors with spacers of the same height, for example, to ensure that electrical contacts are produced when the display is under pressure. This process will be complex and touch sensing at all points on the display will not always be effective.

1 schematically shows a touch sensitive (liquid crystal) display device.

2 shows a cross-sectional view of a portion of a touch sensitive (liquid crystal) display device according to the present invention.

3 and 4 illustrate the principle of determining coordinates for a touch of a touch sensitive (liquid crystal) display device according to the present invention.

5 shows another embodiment of a touch sensitive (liquid crystal) display device according to the present invention.

In particular, it is an object of the present invention to overcome these deficiencies.

To this end, the touch sensitive display device according to the present invention comprises a touch sensitive material layer, the touch sensitive display device having means for monitoring the electrical properties of the touch sensitive material layer and for sensing a change in the electrical properties. .

By incorporating a layer with pressure sensing properties (e.g., non-linear resistance, which may be implemented by quantum-tunneling composites or piezoresistive layers, etc.) into the display structure, the display structure itself It has unique touch sensing characteristics.

In this way, the need for structured spacers is avoided, while the entire display area has touch sensing characteristics, thereby increasing touch sensitivity, and such touch sensing displays are also used in the fields of flexible displays and wearable displays. It can be applied. In addition, a pressure sensitive layer is interposed between two optical films (retardation film, polarizer film, etc.) present at the front of the display cell, or the display cell and one of these optical layers. When interposed therebetween, it prevents the deteriorating of the front screen performance (reflecting and reflecting light) caused by the air-substrate interface at the front of the device.

These and other features of the present invention will be apparent from and elucidated with reference to the embodiments described below.

These figures are schematic and not drawn to scale. Corresponding components are generally indicated by the same reference numerals.

1 is an electrical equivalent circuit diagram of a portion of a touch sensitive display device 1 to which the present invention may be applied. In one possible embodiment (as one drive mode, referred to as "passive mode"), this is a pixel defined by the intersection of the row or selection electrode 7 and the column or data electrode 6. Matrix 8. The row electrodes are successively selected by the column driver 4, and the column electrodes are supplied with data through the data register 5. For this purpose, the incoming data 2 is first processed in a processor 3 (if necessary). Mutual synchronization between the row driver 4 and the data register 5 is achieved by drive lines 9.

In another possible embodiment (also referred to as "active mode" as another drive mode), the signal from the row driver 4 is imaged through thin-film transistors (TFT) 10. An electrode is selected, wherein the gate electrode of the TFT 10 is electrically connected to the row electrode 7, and the source electrode is electrically connected to the column electrode. The signal present in the column electrode 6 is transmitted to the image electrode of the pixel 8 connected to the drain electrode through the TFT. The other image electrode is connected to, for example, one (one or more) common counter electrode (s). In FIG. 1, only one thin film transistor (TFT) 10 is shown by way of example only.

2 shows a cross-sectional view of a portion of a touch sensitive liquid crystal device having a lower substrate 11 and an upper substrate 12 and having a liquid crystal layer 13 between the substrates. The touch sensitive liquid crystal device has image electrodes (not shown) on the lower substrate 11 and the other substrate 12. The display device in this example further comprises a polarizer 14, an analyzer 15 and a backlight structure 18, and in this particular example also for example 1/4 · λ Other optical layers 16, such as quarter-lambda plates and protective layers 17, are further included.

According to the invention, a structure or layer 19 having pressure sensing properties is provided, in this particular example provided between the lower substrate 11 and the polarizer 14. The pressure sensitive structure or layer 19 in this example is composed of spacer particles 21 between two transparent conducting layers 20 (eg, indium tin oxide, etc.). Together with pressure sensitive structure 22.

A class of materials suitable for use for the pressure sensitive particles 22 is formed of Quantum Tunneling Composites (QTC). QTC is a polymer composite with conductive particles deposited in its structure. The conductive particles have dendrites. These particles are spaced apart and do not form a physical conductive path. However, tensile or compressive strain on these materials allows these particles to come close to each other. The spatial separation of the particles is reduced by the presence of dendrites. At a certain loading point, the spatial separation of the particles is so close that electrons from one particle can jump through the dendrites to another particle. However, dendrites from two different particles are still not in contact with each other. The quantum tunneling act of electrons causes the resistance of the entire material to be drastically reduced. This nonlinear action causes a transition point to be created that rapidly changes the resistance of the material from 10 ¹² to 10 ⁻¹ Ω.

Thus, QTC is a pressure / force sensitive switching material, the switching characteristic of which is equivalent to a mechanical switch. It can also be molded into different shapes and mixed with other polymers.

In this example, a mixture of normal polymer non-conducting spherical spacers 21 and pressure / force sensing (QTC) spacers 22 is provided between two transparent conductive layers 20. . The regular polymer spacer 21 prevents the QTC spacer 22 from being overloaded and not having plasticity. Another function of the regular polymer spacer is to prevent shorting between the top and bottom layers 20. The diameter of the QTC spacer 22 is preferably less than or equal to the size of the regular polymer spacer 21.

On the other hand, the sensing layer may be a mixture of compressible bonding materials, such as silicone rubber mixed with a conductive spherical spacer having a diameter smaller than the thickness of the compressible silicone rubber layer. have.

Thus, the structure or layer 19 in this example is inherently touch sensitive. This is shown in FIG. 3 (a), which is an electrical equivalent circuit diagram of a pressure sensing structure or layer 19 using a variable resistor 23. 3 and 4 illustrate a method of monitoring the impedance between the upper electrode and the lower electrode.

When no pressure is applied, the impedance between the upper electrode and the lower electrode is close to infinity, and V _read of the voltage source 25 is selected to be near zero as shown in Fig. 3 (a).

Upon contact with the pressure sensitive structure or layer 19, a sharp decrease in resistance indicates a contact action. The magnitude of the pressure is determined by measuring the impedance of the pressure sensitive structure or layer 19. The resistance is Where R _ead is a read resistor, which is indicated by resistor 26 in FIG. 3.

The sensing system can then proceed to detect xy coordinates by using one of the electrodes 20 as a probe. As shown in FIGS. 3 (b) and 3 (c), the voltage Vs can be applied directly or through mutually insulated low impedance strips 24 (metal strips, etc.). Is applied to the edge of. In one direction y, if the pixel has a height H, the y position is Where V _T is the voltage of the QTC spacer layer upon contact. On the other hand If, Becomes

In a similar way, if the pixel has a width W in the other direction x, then the x position Is given by

The sensing system is initiated with a calibration step 31 (FIG. 4), where the values of Vs are calibrated (eg, Vs (0, H), Vs (W, 0) and Vs (0). , 0), where Vs (0,0) is normally grounded). Next, the sensing system is switched to ON if necessary (step 32), and then proceeds to the contact detection mode (step 33). The sensing system then proceeds to detecting x-y coordinates by using one of the electrodes 20 as a probe. The indication of the contact action is determined by measuring the magnitude of the pressure (e.g., by measuring the impedance of the pressure sensitive structure or layer 19, see Figure 3 (a)). If there is a predetermined magnitude of pressure (some kind of threshold, which can be adjusted in step 34 if necessary), the sensing system detects xy coordinates using the method of FIGS. 3 (b) and 3 (c). Proceed to (step 36), and then return to the contact detection mode (arrow 37). If there is too little pressure present, the detection system immediately returns to the contact detection mode (arrow 35).

As shown in FIG. 5, the pressure sensitive layer is also two optical films (retardation film 16 and polarizer 15 in this case) in front of the display device, but the mirror layer, reflective layer and transflective layer. Other types of optical films such as reflective layers, etc. are also possible). The pressure sensitive layer may also be present between the substrate 13 of the display device and one of these optical layers. In this case no additional film is used at the front of the display cell, and the number of air-substrate interfaces that refracts and reflects light at the front of the screen is reduced.

The protected scope of the present invention is not limited to the described embodiments, and the present invention can also be applied to other display devices such as emissive, electrochromic and electrowetting displays and the like. . On the other hand, the regular polymer spacer 21 as shown in FIG. 2 need not always be present.

Instead, a flexible substrate (synthetic material) can be used (wearable display, wearable electronic product).

The present invention includes each and every new feature feature and a combination of each and every feature feature. Reference signs in the claims do not limit their protected scope. The word "comprises" and its derivatives do not exclude the presence of elements other than those mentioned in a claim. Components expressed in the singular do not exclude the presence of a plurality of such components.

Claims (7)

A touch sensitive display device 1 comprising a plurality of pixels 8 and means 3, 4, 5 for applying a driving voltage to the pixels, The contact sensing material layer 19, Means (25, 26) for monitoring the electrical properties of the contact sensitive material layer and for sensing variations in the electrical properties Touch sensitive display device comprising a. The method of claim 1, The touch sensitive display device (19) has at least one nonlinear resistive part. The method of claim 1, The touch sensing layer (19) comprises quantum-tunneling or piezoresistive composites. The method of claim 3, wherein The touch sensitive display device (19) comprises a quantum tunneling composite portion (22). The method of claim 1, The touch sensitive layer (19) is located between the substrate (11, 12) of the display device and other optical layers (14, 15, 16) of the device. The method of claim 1, The touch sensitive layer is located between two optical layers (14, 15, 16) of the device. The method according to claim 5 or 6, The optical layer comprises polarizers, retardation layers, orientation layers, quarter-lambda layers, mirror layers and reflective or transflective Touch sensing display device selected from the group comprising a layer.