Patent Application
20090073150
The present invention relates to a liquid crystal display (LCD) panel with an image sensing system, and an image processing system using the LCD panel.
With the spread of digital still-image cameras and digital video cameras, the demand for a camera function in cellular telephones, computer monitors, and the like has risen in recent years. At present, charge coupled device (CCD) light sensors and complementary metal-oxide semiconductor (CMOS) light sensors are widely used as imaging devices in various electronic products. An imaging device employed in a computer monitor, such as an LCD monitor, is usually set at a peripheral area of the LCD monitor, such as a top area or a side area. When a person uses the LCD monitor, the person faces a display area of the LCD monitor. However, the imaging device can only shoot the person's image from a top or the side, therefore the quality of the image may be relatively low. In addition, in order for the person to provide a clear and complete shoot, the person may have to turn his or her head to face the imaging device. This may be inconvenient and distracting.
What is needed is to provide an LCD panel and an image processing system that can overcome the above-described deficiencies.
In one aspect, a liquid crystal display panel includes a display area and an image sensing system. The image sensing system is arranged in the display area. The image sensing system is capable of sensing ambient light and converting the ambient light into image signals. The display area is capable of displaying images corresponding to the image signals.
Other novel features and advantages will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
Reference will now be made to the drawings to describe exemplary embodiments of the present invention in detail.
The light sensor 26 in each pixel unit 234 can be a CCD light sensor, a CMOS light sensor, or another suitable kind of light sensor. Taking the CMOS light sensor as an example, a circuit diagram of the CMOS light sensor is shown in
An anode of the photodiode 264 is grounded, and a cathode of the photodiode 264 is electrically coupled to a source electrode of the first transistor 261 and a gate electrode of the second transistor 262. A gate electrode of the first transistor 261 is electrically coupled to the first scanning circuit 231 via the reset signal line 267, and a drain electrode of the first transistor 261 is electrically coupled to the reset voltage supply line 265. A drain electrode of the second transistor 262 is electrically coupled to the reset voltage supply line 265, and a source electrode of the second transistor 262 is electrically coupled a source electrode of the third transistor 263. A gate electrode of the third transistor 263 is electrically coupled to the first scanning circuit 231 via the selection signal line 266, and a drain electrode of the third transistor 263 is electrically coupled to the second scanning circuit 232. Typical operation of the light sensor 26 is as follows:
First, when a reset signal RST is supplied via the reset signal line 267 to the gate electrode of the first transistor 261, the first transistor 261 goes into an ON state with predetermined timing. The reset voltage supply line 265 supplies a reset voltage VR to the drain electrode of the first transistor 261 and the drain electrode of the second transistor 263. The photodiode 264 is charged by the reset voltage VR, and the reset voltage VR is applied to the gate electrode of the second transistor 262 simultaneously. Next, when ambient light strikes the photodiode 264, electric charge is accumulated in the photodiode 264. The amount of the electric charge accumulated is proportional to the intensity of the outside light beams. The electric charge accumulated decreases the potential of the source electrode of the first transistor 261 and the potential of the gate electrode of the second transistor 262, which functions as a source follower amplifier. Thus the voltage at the cathode of the photodiode 264 is amplified by the second transistor 262, and is output from the source electrode of the second transistor 262.
After a predetermined period of time has elapsed, a row selection signal SLCT is input from the row selection signal line 266 to the gate electrode of the third transistor 263, which functions as a row selection element. The third transistor 263 goes into an ON state. Voltage output from the second transistor 262 is output from the drain electrode of the third transistor 263, and transferred to the second scanning circuit 232. The second scanning circuit 232 selects such voltage signal as an image signal, and sends the image signal to a following processing unit, such as a digital signal processing (DSP) unit, and the like.
Referring to
The image sensing system 23 is configured for sensing ambient light and converting the ambient light into electrical image signals in analog form. The A/D converter 281 receives the analog image signals, and transforms the analog image signals into digital image signals. Then the DSP 282 processes the digital image signals in a next step, for converting the digital image signals into some specified formats that can be recognized by the MCU 383. The MCU 283 controls the image sensing system 23 to function, the memory 284 to store the digital image signals, and the LCD panel 21 to display the corresponding image at the display area 210.
Referring to
The light sensors 26 of the pixel units 234 are arranged at an inner surface of the color filter 212, adjacent to the liquid crystal layer 213. Each light sensor 26 corresponds to one of the color filter units 215, 216, 217. External light beams are filtered and then strike the light sensor 26. Conductive lines (not shown in
Furthermore, an outside of each light sensor 26, except the side facing the first substrate 211, is covered by a light shielding layer 27. The light shielding layer 27 is for shielding backlight beams coming from a backlight module (not shown) employed in the LCD 20. Thus the light sensor 26 can only detect light beams from an outside of the LCD 20, without any interference or negative influence from the backlight beams. The light shielding layer 27 can be made of metal, metallic oxide, or resin. Typically, the light shielding layer 27 is made of chromium or (Cr) chromic oxide. A thickness of the light shielding layer can be in a range from 1000 nanometer to 1500 nanometer.
Unlike with conventional LCDs, the LCD 20 includes the image sensing system 23 arranged in the display area 210. This built-in type image sensing system 23 is capable of shooting an image directly in front of the LCD 20. Thus when a person uses the LCD 20, the image sensing system 23 can shoot an image of the person from right in front of the person. This frontal-type image has relatively high quality compared to images obtained with conventional LCDs, and can provide much convenience for the person using the LCD 20.
Moreover, the image sensing system 23 is arranged in the display area 210 of the LCD panel 21. There is no need for an additional camera, and the LCD panel 21 and the LCD 20 can be made to be compact and aesthetically pleasing.
Referring to
Referring to
It is to be further understood that even though numerous characteristics and advantages of preferred and exemplary embodiments have been set out in the foregoing description, together with details of structures and functions associated with the embodiments, the disclosure is illustrative only; and changes may be made in detail (including in matters of shape, size, and arrangement of parts) within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 200710076997.9 | Sep 2007 | CN | national |
