CN100410749C - Light sensing touch liquid crystal display - Google Patents

Abstract

A liquid crystal display comprises a first substrate, a second substrate and a plurality of pixel units. The second substrate is parallel to and faces the first substrate. A plurality of pixel units are formed between the first substrate and the second substrate, and each pixel unit is provided with a light reflection piece and a light sensor. The light reflection member is disposed on the first substrate. The light sensor is formed on the second substrate and used for outputting a sensing parameter according to the light reflected by the light reflection element from the backlight module. When an external force is applied to the first substrate, the sensing parameter value output by the optical sensor is changed to determine the position of the pixel unit relative to the position where the external force is applied.

Description

Light Sensing Touch LCD Display

technical field

The invention relates to a liquid crystal display, in particular to a touch-sensitive liquid crystal display.

Background technique

Displays with advanced functions have gradually become an important feature of today's consumer electronics products. Liquid crystal displays have gradually become widely used in various electronic devices such as mobile phones, personal digital assistants (PDAs), digital cameras, computer screens or notebook computer screens. monitor with high resolution color screen.

Since the current liquid crystal display is convenient to carry and use, the touch-sensitive liquid crystal display panel that the user can directly touch has also become the direction of market development. In traditional resistive or capacitive touch liquid crystal display panels, additional resistive and capacitive components are arranged on the panel, and the position coordinates of the touch pressure are determined by detecting the change of the voltage value of the touch pressure point. However, since components such as resistors and capacitors are directly arranged on the panel, the light transmittance of the liquid crystal display panel will decrease, and the overall thickness of the panel will increase. Another type of optical touch panel is to arrange a large number of light sources and corresponding optical sensing components around the liquid crystal display panel, and use the optical sensing components to detect the light of the corresponding light source to determine the position coordinates of the touch point . Although such a design will not reduce the light transmittance of the panel, it will greatly increase the volume of the product, so it is not suitable for general portable liquid crystal displays.

Therefore, if the sensing components can be integrated into the liquid crystal panel, not only can the overall weight and volume of the liquid crystal display be reduced, but it will be beneficial to the current liquid crystal display products that emphasize thin and light design.

Contents of the invention

The purpose of the present invention is to provide a touch-sensitive liquid crystal display. The light sensor is directly arranged in the liquid crystal display panel, so that when an external force touches and presses the liquid crystal display panel, the external force is detected by the light intensity detected by the light sensor. The position of the touch.

An embodiment of the present invention provides a liquid crystal display including a first substrate, a second substrate and a plurality of pixel units. The second substrate is parallel to and faces the first substrate. A plurality of pixel units are formed between the first substrate and the second substrate, and each pixel unit has a light reflector and a light sensor. The light reflector is disposed on the first substrate. The light sensor is formed on the second substrate, and the light sensor is used to output a sensing parameter according to the light reflected from the backlight module by the light reflector. When an external force is applied to the first substrate, the value of the sensing parameter output by the light sensor will be changed to determine the position of the pixel unit relative to the place where the external force is applied.

Description of drawings

FIG. 1 is a schematic diagram of a liquid crystal display of the present invention.

FIG. 2 is a circuit diagram of the liquid crystal display panel and the judging unit of FIG. 1 .

FIG. 3 is a partial structural diagram of the liquid crystal display panel and the light source in FIG. 1 .

FIG. 4 is a schematic diagram of deformation of the liquid crystal display panel of FIG. 3 when an external force is applied.

Description of reference symbols

100 Liquid Crystal Display 102 Gate Driver

104 source driver 106 judging unit

110 LCD panel 112 Scanning lines

114 data line 116 transmission line

120 Liquid crystal molecules 130 Light source

154 Light reflector 156 Black matrix layer

200 Pixel Units 202 Switching Transistors

204 storage capacitor 206 liquid crystal capacitor

210 detection circuit 150, 152 conductive substrate

212 conversion circuit 250 decision unit

216 switch unit 218 light sensor

211 Transistor 214 Operational Amplifier

221, 222 input terminal 223 output terminal

Detailed ways

Please refer to FIG. 1 , which is a schematic diagram of a liquid crystal display 100 of the present invention. The liquid crystal display 100 includes a light source 130 , a gate driver 102 , a source driver 104 , a determination unit 106 and a liquid crystal display panel 110 . The above-mentioned components are all wrapped in a casing (not shown in the figure). The gate driver 102 is used to generate a scan signal and transmit it to the LCD panel 110 through the scan line 112 . The source driver 104 is used to generate a data signal voltage and transmit it to the LCD panel 110 through the data line 114 . The judging unit 106 is coupled to the liquid crystal display panel 110 through the transmission line 116 and used for detecting the position where the liquid crystal display panel 110 is pressed. The light source 130 can be a cold cathode ray tube for generating the backlight required by the liquid crystal display panel 110 .

Please refer to FIG. 2 together. FIG. 2 is a circuit diagram of the liquid crystal display panel 110 and the determination unit 106 in FIG. 1 . The liquid crystal display panel 110 includes a plurality of pixel units 200 , and each pixel unit 200 includes a switching transistor 202 , a storage capacitor 204 and a liquid crystal capacitor 206 . The liquid crystal capacitor 206 is composed of two electrodes, one electrode is connected to a common voltage terminal Vcom, and the other electrode is connected to the switching transistor 202, and liquid crystal molecules are distributed between the two electrodes. When the gate of the switch transistor 202 receives the scan signal generated by the gate driver 102 from the scan line 112 , it conducts the data signal voltage generated by the source driver 104 to the liquid crystal capacitor 206 via the data line 114 . The liquid crystal molecules of the liquid crystal capacitor 206 generate different alignment directions according to the common voltage generated by the common voltage terminal Vcom and the voltage difference of the data signal voltage, so as to control the intensity of light passing through the liquid crystal molecules. The storage capacitor 204 is used to store the data signal voltage, so that the liquid crystal capacitor 206 can still maintain the voltage difference between the data signal voltage and the common voltage when the switching transistor 202 is turned off, so that the light intensity passing through the liquid crystal molecules remains constant. In addition, the liquid crystal display panel 110 is provided with a plurality of transistors 211 and a plurality of light sensors 218 . The light sensor 218 is used to generate different sensing parameters according to the light intensity. For example, the light sensor 218 can be a light sensing transistor, which is coupled to a bias terminal Vbias and used to generate different sensing currents according to the light intensity. The transistor 211 is used to conduct the sensing current generated by the light sensor 218 when turned on. In addition, the pixel unit 200 further includes a storage capacitor 219 for storing the sensing current generated by the light sensor 218 .

Please refer to FIG. 3 and FIG. 4 . FIG. 3 is a partial structural diagram of the liquid crystal display panel 110 and the light source 120 in FIG. 1 , and FIG. 4 is a schematic diagram of deformation of the liquid crystal display panel 110 in FIG. The liquid crystal display panel 110 includes a first substrate 150 , a second substrate 152 and a black matrix layer 156 . The first substrate 150 and the second substrate 152 are transparent conductive substrates. The pixel unit 200 is formed between the first substrate 150 and the second substrate 152 . Each pixel unit 200 includes a light sensor 218 and a light reflector 154 . The light sensor 218 is formed on the second substrate 152 . The light reflector 154 protrudes from the first substrate 150 and corresponds to the position of the light sensor 218 . The light reflector 154 is used to reflect the light emitted by the light source 130 , so its material can be metal with better reflectivity. In addition, the black matrix layer 156 can be an opaque resin, which is formed on the first substrate 150 and is not formed on the position corresponding to the light sensor 218 for shielding the light emitted by the light source 130 . The first and second substrates 150 and 152 are transparent conductive substrates, and liquid crystal molecules 120 are placed between the two substrates 150 and 152 . As shown in FIG. 3 , when no external force is applied to the first substrate 150 , the light sensor 218 can receive the light emitted by the light source 130 . As shown in FIG. 4 , when an external force A is applied to a pressure point of the first substrate 150 , the distance between the first substrate 150 and the second substrate 152 at the pressure point will be shortened. At this time, the light emitted from the light source 130 will be reflected by the light reflector 154 , so that the intensity of the light received by the light sensor 218 is weaker than that when no force is applied to the touch point. Since the light sensor 218 generates a sensing current according to the intensity of the received light, and the stronger the intensity of the received light, the greater the sensing current. The sensing current (as shown in FIG. 3 ) is greater than the sensing current (as shown in FIG. 4 ) generated by applying force to the touch point.

See Figure 2. The light sensor 218 generates different sensing currents according to different light intensities, and outputs the sensing currents to the conversion circuit 212 . The conversion circuit 212 includes an operational amplifier 214 , a feedback capacitor Cf and a switch unit 216 . The operational amplifier 214 includes a first input terminal 221 , a second input terminal 222 and an output terminal 223 . The first input terminal is coupled to a reference voltage terminal Vref, and the reference voltage terminal Vref is used to provide a DC reference voltage. The entire converting circuit 212 can be regarded as an integrating circuit. When the scan line 112 transmits a scan signal, the switch unit 216 is turned off (turn-off). On the contrary, when the scan line 112 does not transmit a scan signal, the switch unit 216 will be turned on (turn-on), so that the second input terminal 222 and the output terminal 223 are short-circuited, and at this time the voltage of the output terminal 223 is equal to the DC reference Voltage. When the switch unit 216 is turned off (turn-off), the output voltage Vout of the output terminal 223 of the operational amplifier 214 satisfies Equation 1:

$\mathrm{Vout}=-\mathrm{Vc}=-\frac{I\×t}{\mathrm{Cf}}$ Formula 1

Wherein, I represents the sensing current generated by the light sensor 218 , and t represents time.

Next, the operational amplifier 214 converts the sensing current transmitted by the light sensor 218 into a sensing voltage. Because the sensing current output by the light sensor 218 corresponding to the contact pressure point with external force is relatively small, the sensing voltage output by the converting circuit is also relatively small. Finally, the determination unit 250 receives the sensing voltages output by each operational amplifier 214 , and judges the corresponding coordinates of the touch points on the liquid crystal display panel 110 according to the magnitude of the sensing voltages.

The distance between the first substrate 150 and the second substrate 152 will be different due to the different external forces that touch the first substrate 150, which will affect the intensity of light sensed by the photosensor 218 and the sensitivity of its output. Measure the current. Therefore, the magnitudes of the sensing voltages output by the operational amplifier 214 are also different. Therefore, in terms of design, in addition to determining the coordinates of the touched point, the determining unit 250 can also determine the magnitude of the external force applied to the touched point according to the output voltage of each operational amplifier 214 .

In the liquid crystal display of the present invention, a plurality of light sensors are integrated into the liquid crystal display panel, and the coordinates of the touch point on the liquid crystal display panel are judged by the difference in light intensity received by the light sensors. Since the light sensor is integrated in the liquid crystal display panel, not only the overall weight and volume of the liquid crystal display can be reduced, but also it is beneficial to the current liquid crystal display products that emphasize thin and light design.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any skilled person can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore The scope of protection of the present invention should be defined by the patent scope of the present invention.

Claims (10)

1. LCD comprises:

One first substrate;

One second substrate, parallel and be intended for this first substrate;

One backlight module is used to provide the required light source of this display;

A plurality of pixel cells be formed between this first substrate and this second substrate, and each this pixel cell comprise:

One smooth reflecting element is arranged on this first substrate; And

One OPTICAL SENSORS is formed on this second substrate, and this OPTICAL SENSORS is used for exporting a sensor parameter according to the light of this light reflecting element reflection from this backlight module;

Wherein, when applying an external force, can change this sensor parameter value of this OPTICAL SENSORS output, apply this pixel cell position at external force place in order to judgement in first substrate.

2. LCD as claimed in claim 1 more comprises a judging unit, in order to receive this sensor parameter from this OPTICAL SENSORS output.

3. LCD as claimed in claim 2, wherein, this judging unit comprises:

A plurality of integrating circuit are used for exporting a sensing voltage according to this sensor parameter; And

One decision unit is used for judging the position that this sensing voltage is originated according to the sensing voltage of these a plurality of integrating circuit outputs.

4. LCD as claimed in claim 1, wherein, this OPTICAL SENSORS is a light sensing transistor, is used for producing this sensor parameter according to the light intensity to should light sensing transistorized this light reflecting element reflection.

5. LCD as claimed in claim 2 more comprises a plurality of transistors, and each transistor is formed on this second substrate and is coupled to this OPTICAL SENSORS, is used for transmitting this sensor parameter to this judging unit.

6. LCD as claimed in claim 1, it comprises a black-matrix layer in addition, is formed at this first substrate and is not formed on the position corresponding to this OPTICAL SENSORS, is used for covering the light that the light source of this backlight module sends.

7. LCD as claimed in claim 6, wherein, this light reflecting element protrudes on this first substrate position with respect to this OPTICAL SENSORS, is used for reflecting the light that this light source sends.

8. LCD as claimed in claim 6, wherein, this OPTICAL SENSORS is the light sensing transistor, is used for producing this sensor parameter according to the light intensity to should light sensing transistorized this light reflecting element reflection.

9. LCD as claimed in claim 8 wherein, more comprises a judging unit and comprises:

A plurality of integrating circuit are used for exporting a sensing voltage according to this sensor parameter; And

One decision unit is used for judging the position that this sensing voltage is originated according to the sensing voltage of these a plurality of integrating circuit outputs.

10. LCD as claimed in claim 8, wherein, this first, second substrate is a transparency carrier.

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